cimav.repositorioinstitucional.mx€¦ · !!...
139
MESYRUM 2014
Transcript of cimav.repositorioinstitucional.mx€¦ · !!...
MESYRUM 2014
UNPA MESYRUM 2014
2
BOOK OF ABSTRACTS
UNPA MESYRUM 2014
3
PAPALOAPAN UNIVERSITY
Dr. Modesto Seara Vázquez Rector
M.C. Héctor López Arjona
Academic Vice-rector
L.C.P. Rubén Jiménez Cervantes Administrative Vice-rector
UNPA MESYRUM 2014
4
ORGANIZERS
LOCAL ORGANIZERS
• Dr. Erick A. Juarez-Arellano (UNPA) – Coordinator • Dr. Mario Valera Zaragoza (UNPA) • Dra. Yadira Gochi Ponce (ITO) • Dra. Nelda X. Martínez Galero (UNPA) • Dra. Ana K. Navarro Martínez (UNPA) • M.C. Isaac Machorro Cano (UNPA) • M.C. Mónica Guadalupe Segura Ozuna (UNPA) • Dra. Delia E. Páramo Calderón (UNPA) • Dr. Alejandro Aparicio Saguilán (UNPA) • Dr. Rafael Martínez Martínez (UTM) • Dr. Guillermo Juárez López (UTM) • M.C. Héctor López Arjona (UNPA)
UNPA MESYRUM 2014
5
NATIONAL ORGANIZERS
• Dra. Guadalupe de la Rosa (Universidad de Guanajuato) • Dr. Daniel Hernández Cruz (Universidad Autónoma de Chiapas) • Dr. Mauro Napsuciale Mendívil (Universidad de Guanajuato) • Dr. Abel Moreno Cárcamo (Universidad Nacional Autónoma de México) • Dr. Erick A. Juarez-Arellano (Universidad del Papaloapan, Oaxaca) • Dr. Gustavo Cruz Jiménez (Universidad de Guanajuato) • Dr. Juan Carlos Fierro González (Instituto Tecnológico de Celaya) • Dr. Luis E. Fuentes Cobas (Centro de Investigación en Materiales
Avanzados, Chihuahua)
ADVISORY COMMITTEE
• Dr. Matías Moreno Yntriago(UNAM) • Dr. José Ignacio Jiménez Mier y Terán(UNAM) • Dr. Antonio Marcelo Juárez Reyes (UNAM) • Dr. Armando AntillónDíaz (UNAM) • Dr. José Mustre (CINVESTAV) • Dr. TomásViveros (UAM) • Dr. Guillermo Hinojosa Aguirre (UNAM)
UNPA MESYRUM 2014
6
PROGRAM
Time Thursday 27/11 Friday 28/11
9:00 - 9:15 Björn Winkler
9:15 - 9:30
9:30 - 9:45 Andrea Lausi
9:45 - 10:00 Matías Moreno
10:00 - 10:15 The Mexican Synchrotron Project in Morelos
10:15 - 10:30 Guadalupe de la Rosa Gastón García
10:30 - 10:45 Presentation of the Synchrotron Users Network (RedTULS) The ALBA synchrotron light source
10:45 - 11:00 José Jiménez-Mier Francis Pérez
11:00 - 11:15 The Early Days of Synchrotron Radiation in the World and in Mexico ALBA
11:15 - 11:30
11:30 - 11:45
11:45 - 12:00 Daniel Hernández-Cruz Abel Moreno Cárcamo
12:00 - 12:15Polymer fibers and cementitious matrix
interaction: a multiscale characterization
Myths and realities about chemical and Physical Parameters on the Protein
Crystallization
12:15 - 12:30 Edilso Reguera Sergio A. Gómez Torres
12:30 - 12:45 Applications of Synchrotron Radiation to Solve Complex Structural Problems
XANES and EXAFS Structural Characterization of Catalysts
12:45 - 13:00 Luis E. Fuentes-Cobas Maria E. Montero-Cabrera
13:00 - 13:15 Synchrotron light diffraction and scattering in functional materials
Application of the X-ray absorption fine structure (XAFS) in functional and
environmental materials
13:15 - 15:45 Lunch Lunch
Coffee Break
Recent developments in high pressure diffraction experiments
Opening Ceremony
Diffraction at Elettra and Fermi
Coffee Break
UNPA MESYRUM 2014
7
13:15 - 15:45 Lunch Lunch
15:45 - 16:00 Antonio Romero Hiram Castillo-Michel
16:00 - 16:15
16:15 - 16:30
16:30 - 16:45 Rogerio R. Sotelo-Mundo Vivian Stojanoff
16:45 - 17:00Synchrotron single-crystal
crystallography as a novel resource in crustacean biology and aquatic health
Synchrotron Radiation applications in Life Sciences
17:00 - 17:15
17:15 - 17:30
17:30 - 17:45
17:45 - 18:00 Paul Olalde-Velasco
18:00 - 18:15First direct observation of single
magnons by oxygen K-edge RIXS on iridates
18:15 - 18:30 Riccardo Bartolini
18:30 - 18:45 Diamond 10 years vision
18:45 - 19:00 Robert Hettel
19:00 - 19:15 SSRL Now and in the Future
19:15 - 19:30 David A. Shapiro
19:30 - 19:45
19:45 - 20:00 Closing Ceremony
Poster Session Coffee break
Poster Session Coffee break
Unmasking pathogenicity and virulence: A structural approach using
synchrotron radiation
The ID21 beamline at the European Synchrotron Radiation Facility: a multi-
analytical platform for micro-spectroscopic analyses
Soft X-ray Ptychography for Nano-Materials Research
1st MESYRUA General Assembly
UNPA MESYRUM 2014
8
CONTENTS
SYNCHROTRON RADIATION APPLICATIONS IN LIFE SCIENCES ..................... 15 Andrea Lausi
UNMASKING PATHOGENICITY AND VIRULENCE: A STRUCTURAL APPROACH USING SYNCHROTRON RADIATION .................................................... 16 Federico M. Ruiz, Elena Santillana, Mercedes Spínola-Amilibia, Francisco Javier Medrano, Antonio Romero
SOFT X-RAY PTYCHOGRAPHY FOR NANO-MATERIALS RESEARCH .............. 17 David A. Shapiro, Young-Sang Yu, Maryam Farmand, Tolek Tyliszczak, Jordi Cabana, A.L. David Kilcoyne, Filipe Maia, Stefano Marchesini, Tony Warwick, and Howard A. Padmore
THE ID21 BEAMLINE AT THE EUROPEAN SYNCHROTRON RADIATION FACILITY: A MULTI-ANALYTICAL PLATFORM FOR MICRO-SPECTROSCOPIC ANALYSES .......................................................................................... 19 Hiram Castillo-Michel, Marine Cotte, Murielle Salomé, Barbara Fayard, Emiline Pouyet, Camille Rivard, David Bugnazet, Eric Gagliardini, Gilles Berruyer, Jean Susini
SYNCHROTRON RADIATION APPLICATIONS IN LIFE SCIENCES .................. 221 Vivian Stojanoff
CURRENT DEVELOPMENTS FOR HIGH PRESSURE DIFFRACTION STUDIES USING SYNCHROTRON RADIATION ............................................................................ 22 Bjoern Winkler
THE ALBA SYNCHROTRON LIGHT SOURCE ............................................................. 23 Gastón García López
SSRL NOW AND IN THE FUTURE ................................................................................... 25 Robert Hettel
PRESENTATION OF THE SYNCHROTRON USERS NETWORK (REDTULS) ...... 26 Guadalupe de la Rosa
APPLICATIONS OF SYNCHROTRON RADIATION TO SOLVE COMPLEX STRUCTURAL PROBLEMS ............................................................................................... 27 Edilso Reguera
THE EARLY DAYS OF SYNCHROTRON RADIATION IN THE WORLD AND IN MEXICO .................................................................................................................................. 30 José Jiménez-Mier
UNPA MESYRUM 2014
9
MYTHS AND REALITIES ABOUT CHEMICAL AND PHYSICAL PARAMETERS ON THE PROTEIN CRYSTALLIZATION ....................................................................... 31 Abel Moreno
SYNCHROTRON LIGHT DIFFRACTION AND SCATTERING IN FUNCTIONAL MATERIALS ....................................................................................................................... 322 Luis Fuentes-Montero, María E. Fuentes-Montero, María E. Montero-Cabrera and Luis E. Fuentes-Cobas
APPLICATION OF THE X-RAY ABSORPTION FINE STRUCTURE (XAFS) IN FUNCTIONAL AND ENVIRONMENTAL MATERIALS .............................................. 35 Isaí Castillo-Sandoval, Edgar Macías-Ríos, Iván J. Carreño-Márquez, Luis E. Fuentes-Cobas, María E. Fuentes-Montero, Hilda E. Esparza Ponce, Maria E. Montero-Cabrera
THE MEXICAN SYNCHROTRON PROJECT IN MORELOS ..................................... 38 Matías F. Moreno Yntriago
X-RAY ABSORPTION NEAR EDGE SPECTROSCOPY AS A TOOL DETERMINE ATOMIC LOCALS STRUCTURE ...................................................................................... 39 Jose Mustre de León
FIRST DIRECT OBSERVATION OF SINGLE MAGNONS BY OXYGEN K-EDGE RIXS ON IRIDATES. ............................................................................................................ 41 Paul Olalde-Velasco, Yaobo Huang, Valentina Bisogni, Jonathan Pelliciari, Marcus Dantz, Sara Fatale, James Vale, Jun Miyawaki, Yoshihisa Harada, Alessandro Nicolau, Sorin Chiuzbăian, Desmond McMorrow, Dharmalingam Prabhakaran, Andrew Boothroyd, Johan Chang, Henrick Rønnow, Vladimir Strokov and Thorsten Schmitt
SYNCHROTRON SINGLE-CRYSTAL CRYSTALLOGRAPHY AS A NOVEL RESOURCE IN CRUSTACEAN BIOLOGY AND AQUATIC HEALTH ..................... 43 Rogerio R. Sotelo-Mundo, Alonso López-Zavala, Enrique Rudiño-Piñera, Luis G. Brieba, Vivian Stojanoff
XANES AND EXAFS STRUCTURAL CHARACTERIZATION OF CATALYSTS ................................................................................................................................................... 44 Sergio A. Gómez Torres
POLYMER FIBERS AND CEMENTITIOUS MATRIX INTERACTION: A MULTISCALE CHARACTERIZATION ........................................................................... 46 Daniel Hernández-Cruz, Craig W. Hargis, Sungchul Bae, Pierre A. Itty, Cagla Meral, Jolee Dominowski, Michael J. Radle, Wilson L. Nguyen, David A. Kilcoyne, Dula Parkinson, Paulo J.M. Monteiro, Claudia P. Ostertag
APPLIED SYNCHROTRON RADIATION IN THE STUDY OF HYBRID MATERIALS .......................................................................................................................... 48 Marlene González, A. Adela. Lemus-Santana, Joelis. Rodríguez-Hernández, Marcelo Knobel, Edilso Reguera
UNPA MESYRUM 2014
10
CHARACTERIZATION AND EVALUATION OF THE ADSORPTION OF PB (II) BY TYPHA LATIFOLIA ROOTS ................................................................................................ 50 Candy Carranza-Alvarez, Luis Rodrigo Ramiro Bautista, Alejandro Hernández-Morales, Juan José Maldonado-Miranda, Nahúm Medellín-Castillo
USE OF SYNCHROTRON INFRARED MICROSPECTROSCOPY FOR MOLECULAR IDENTIFICATION OF USEFUL PRODUCTS OBTAINED FROM LIGNOCELULOSIC MATERIALS PRETREATED WITH STEAM EXPLOSION. ................................................................................................................................................... 53 Carlos Molina, Arturo Sánchez, Idania Valdez-Vazquez, Delfino Francia, Guadalupe de la Rosa Álvarez
STRUCTURAL STUDY OF SOLID SOLUTIONS W1-XMOXO3-0.33H2O AND BI2W1-
XMOXO6 ................................................................................................................................... 54 A. Arzola-Rubio, S. Basurto-Cereceda, J. Camarillo-Cisneros, L. Fuentes-Cobas, C. Ornelas and F. Paraguay- Delgado
THEORY AND EXPERIMENT FOR THE SINGLE PHOTOIONIZATION OF P+. ................................................................................................................................................... 56 E. M. Hernández, Sultana Nahar, A. Aguilar, Olmo González, D. Macaluso, A. Antillón, A. Morales-Mori, A. M. Juárez, D. Hanstorp, Aaron Covington, Kiattichart Chatkunch and G. Hinojosa
THE USE OF SYNCHROTRON RADIATION IN SURFACE SCIENCE .................... 58 Leonardo Morales de la Garza
ARGININE KINASE CRYSTAL STRUCTURE IN COMPLEX WITH ARGININE SHOWS PRE-ORGANIZED PHOSPHAGEN BINDING SITE ...................................... 59 Alonso A. Lopez-Zavala, Rogerio R. Sotelo-Mundo, Enrique Rudiño-Piñera,Vivian Stojanoff
ANALYSIS OF THE SINTERING OF POWDER SYSTEMS BY IN SITU SYNCHROTRON MICROTOMOGRAPHY ..................................................................... 61 L. Olmos, D. Bouvard, Christophe L. Martin, M. Di Michiel
INDOOR/OUTDOOR CHARACTERIZATION OF ISOTOPIC RATIOS OF LEAD IN AN ATMOSPHERE-POLLUTED AREA OF CHIHUAHUA CITY, MEXICO ........... 63 Marcos Delgado Rios, Jorge L. Gardea-Torresdey, Jason Parsons, Jose R. Peralta-Videa, Gustavo Cruz-Jimenez, Elias Ramirez Espinoza
STUDY OF CONFORMATIONAL CHANGE CELL WALL PROTEINS OF CANDIDA SPECIES DURING BIOFILM FORMATION USING STXM AND FTIR TECHNIQUES ........................................................................................................................ 65 Mayra Cuéllar-Cruz, Daniel Hernández-Cruz and Enrique Rudiño-Piñera
UNPA MESYRUM 2014
11
SAXS STUDIES TO CHARACTERIZE THE INTERACTION OF THE RIBOSOMAL GTPASE EFL1 AND SBDS ................................................................................................... 67 Eugenio de la Mora, Abel Moreno and Nuria Sánchez-Puig
SYNTHESIS AND CHARACTERIZATION OF ZRO2: SM3+ FILMS PREPARED BY ULTRASONIC SPRAY PYROLYSIS TECHNIQUE. ...................................................... 69 R. Martínez-Martínez, G. Juárez-López, J.J. Carmona-Rodríguez, I. E. Velázquez-Cruz, G. Flores, E. Zaleta-Alejandre and C. Falcony
NON-CONVENTIONAL TECHNIQUES FOR PROTEIN CRYSTALLIZATION AND CRYSTAL GROWTH ........................................................................................................... 71 Nuria Sánchez-Puig, Roberto Arreguín, Jean Jakoncic, Vivian Stojanoff and Abel Moreno
CONCRETE DETERIORATION AND ITS RELATION WITH THE ENVIRONMENT. .................................................................................................................. 74 T. Pérez, J. T. Pérez-Quiroz, M. Sosa-Baz
APPLY SMART SENSITIVITY CONTROL WITHAGILENT’S NEW RANGE OF S2 CCD DETECTORS ................................................................................................................ 77 Daniel Baker, Fraser White, Zolt.nG.l, Mathias Meyer, PrzemysławStec, Angel Sanz
LYASE ACTIVITY OF GLYCOGEN SYNTHASE: IS AN ELIMINATION/ADDITION MECHANISM A POSSIBLE REACTION PATHWAY FOR RETAINING GLYCOSYLTRANSFERASES? ........................................................ 79 Adelaida Díaz, Mireia Díaz-Lobo, Enrique Grados, Joan J. Guinovart, Ignacio Fita and Joan C. Ferrer
ELECTROCHEMICAL ANALYSIS OF PT CHALCOGENIDES SYNTHESIZED BY A DISPERSION METHOD .................................................................................................. 81 Adriana Sigüenza Orozco, Zaira Itzel Bedolla Valdez, María de Jesús Gil Gallegos, Yadira Gochi Ponce
NANOMATERIALS FOR LEUKEMIA STUDY: AN OPORTUNITY FOR SYNCHROTRON LIGHT TO CHARACTERIZE GOLD NANOSTARS ..................... 84 Juan C. Martínez-Espinosa, José de Jesus Ibarra-Sanchez, Ana Karen Zavala Raya, V. H. Romero, Miguel José Yacaman, M. Guadalupe de la Rosa Álvarez
TEXTURE DETERMINATION OF ZNO NANORODS USING 2D SYNCHROTRON DIFFRACTION AND ITS SIMULATION BY ANAELU. ............................................... 86 A. Sáenz-Trevizo, L. Fuentes-Cobas, P. Amézaga-Madrid, P. Pizá-Ruíz, W. Antúnez-Flores and M. Miki-Yoshida
TEM ANALYSIS OF CUX(CDTE)YOZ THIN FILMS .................................................... 88 A. Miguel-Hernández, P. del Angel-Vicente, S. Jiménez-Sandoval, R. Lozada-Morales, J. A. Montoya de la Fuente, O. Jiménez-Sandoval, R. Martinez-Martinez, G. Juarez-Lopez, J. Carmona-Rodríguez
UNPA MESYRUM 2014
12
USE OF SYNCHROTRON INFRARED MICROSPECTROSCOPY FOR MOLECULAR IDENTIFICATION OF USEFUL PRODUCTS OBTAINED FROM LIGNOCELULOSIC MATERIALS PRETREATED WITH STEAM EXPLOSION. ................................................................................................................................................... 90 Carlos Molinaa, Arturo Sánchezb, Idania Valdez-Vazquezc, Delfino Franciad, Graciela Ruiz-Aguilard, Guadalupe de la Rosa Álvarez
COMPARATION OF LEAD AND CADMIUM ACCUMULATION BY TYPHA LATIFOLIA (ESPADAÑA) AND PISTIA STRATIOTES (WATER LETTUCE) ........... 91 Claudia E. Moctezuma-Granados, Alejandro Hernandez-Morales, Candy Carranza-Álvarez
FOLLOWING SDSA1 CRYSTALLIZATION AND ITS INHIBITION BY USING SYNCHROTRON RADIATION .......................................................................................... 94 Omar Mendoza Llerenas, Juan Alberto Osuna Castro, Abel Moreno Cárcamo, Jean Jakoncic, Nuria Sánchez Puig
STRUCTURAL STUDIES OF DNA LIGASE FROM THERMOCOCCUS GAMMATOLERANS .............................................................................................................. 96 Edith Flores Hernández, César Cardona Felix y Enrique Rudiño Piñera
SPECIATION OF FE IN PARTICULATE MATTER PM10 BY X-RAY ABSORPTION SPECTROSCOPY (XAS) AND MICRO X-RAY FLUORESCENCE(µ-XRF) TO IDENTIFY THE EMITTING SOURCE IN THE CITY OF LEON, GUANAJUATO. ................................................................................................................................................... 98 Gladys Morales-‐López, Ma. G. de la Rosa Álvarez, Ma. G. García Jiménez, J.M. Martinez Rosales, Diana O. Rocha Amador, Marcos Delgado Ríos, Hiram Castillo Michel, Jorge L. Gardea Torresdey, Gustavo Cruz Jiménez
DETERMINATION OF EXPOSURE TO BENZENE IN CHILD POPULATION FROM TULA DE ALLENDE CITY, HIDALGO, MÉXICO. ....................................... 101 Israel Enciso-Donis, Gustavo Cruz-Jiménez, Rogelio Costilla-Salazar, Diana O. Rocha-Amador, Fátima del Carmen Durán-Mendoza, Ma. Guadalupe de la Rosa-Álvarez, Nadia A. Pelallo-Martínez
MORPHOLOGICAL STUDY OF CARBON NANOTUBES MULTI-WALLED ...... 104 Karla J. Tomás-Sebastián, Bonfilio Javier Arango Perdomo, María de Jesús Gil-Gallegos, Yadira Gochi-Ponce
CRYSTALLIZATION OF CATALASE-PEROXIDASE FROM NEUROSPORA CRASSA ................................................................................................................................ 106 Lizbeth García, Vanessa Vega García, Adelaida Díaz, Enrique Rudiño-Piñera and Wilhelm Hansberg
RESINGLE PHOTOIONIZATION OF ALUMINIUM LIKE P2+ ................................ 108 Lorenzo Hernández, Aaron Covington, Edgar Hernández, Armando Antillon, Alejandro Morales, Kiattichart Chartkunchand, Alejandro Aguilar and Guillermo Hinojosa
UNPA MESYRUM 2014
13
PROCESS TO OBTAIN FOAMS OF A356 ALUMINUM ALLOY USING THERMAL THREATED TIH2 AS FOAMING AGENT ..................................................................... 111 Manuel I. Romero-Romero, Carlos Domínguez-Ríos, Alfredo Aguilar-Elguezabal, Roal Torres-Sánchez
INDUSTRIAL UPGRADING OF ULTRASONIC SPRAY PYROLYSIS TECHNIQUE APPLIED ON HANDICRAFTS OF BLACK CLAY. ..................................................... 114 Martha P. García-Ramírez, Rafael Martínez-Martínez, Guillermo Juárez-López, Evaristo I. Velázquez-Cruz, Julián J. Carmona-Rodríguez, Ciro Falcony-Guajardo
MECHANOCHEMICAL SYNTHESIS AND CHARACTERIZATION OF REC AND REB2 ...................................................................................................................................... 117 Mizraim G. Granados-Fitch, Juan M. Quintana-Melgoza, Erick A. Juarez-Arellano, Miguel Ávalos-Borja
SIZE CONTROL IN THE SINTHESYS OF MAGNETIC NANOPARTICLES FOR BIOMEDICAL APPLICATIONS ..................................................................................... 119 José de Jesus Ibarra-Sanchez, Juan C. Martínez-Espinosa, Pablo Villegas Molina, María L.Vera-Yepez, Teodoro Cordova-Fraga, María G. De la Rosa-Alvarez
INFLUENCE OF THE LENGTH ON THE MECHANICAL TENSION TO THE FIBERS PROPERTIES AGAVE ANGUSTIFOLIA HAW ........................................... 121 Rey F. García-Méndez, Yadira Gochi-Ponce, Froylan Martínez-Suarez
SYNTHESIS OFPLATINUM CHALCOGENIDES AND COBALT SPINELS IN DISORDERED PHASEBY THE METHODS OF CHALCOGEN DISPERSION AND MECHANIC MILLING ..................................................................................................... 122 Salvador Aguilar Hernández, E. A. Juarez-Arellano, Marco A. Sánchez Medina,Y. Gochi Ponce
THERMAL PROPERTIES OF POLYPROPYLENE COMPOSITES AND CARBONALLOTROPE ..................................................................................................... 125 J. Avendaño García, C. Velasco Santos, A. L. Martínez Hernández, A. D. Pérez Santiago,Y. Gochi-Ponce
EVALUATION OF DIFFERENT CULTURE MEDIA TO IMPROVE THE PRODUCTION OF PARASPORAL CRYSTALS IN BACILLUS THURINGIENSIS ....................................................................................................... 127 Alain Cruz-Nolasco, Rigoberto Martínez-García, Erick A. Juarez-Arellano, A. Karin Navarro-Mtz
COUNT OF PUBLICATIONS PER YEAR ABOUT THE DIFFERENT BEAMLINES COUNTED BY DIAMOND LIGHT SOURCE (DLS). ................................................... 129 Alvaro Bahena Bárcenas
SOLVOTHERMAL SYNTHESIS AND CHARACTERIZATION OF FE-BTC AND CU-BTC FOR HYDROGEN STORAGE AND METHANE CAPTURE. .................... 131 Jade A. Galicia, Neil Torres Figueredo, Erick A. Juarez-Arellano, E. Reguera-Ruiz, Adela Lemus S.
UNPA MESYRUM 2014
14
SYNTHESIS AND CHARACTERIZATION OF MGO COMPOUNDS WITH MNO2 AND B IMPURITIES, AS POTENTIAL HYDROGEN STORAGE MATERIALS. ................................................................................................................................................ 133 A. Martinez-Garcia, S. C. Altamirano Perez, M. Avalos-Borja, E. Reguera, E. A. Juarez-Arellano
STUDY OF THE CHEMICAL AND PHYSICAL BEHAVIOR OF THE COMPOSITE EVA-MGSPE .......................................................................................................................... 135 Guadalupe Palacios Hernández, Alejandro Aparicio-Saguilán, Mario Valera Zaragoza, Erick A. Juarez-Arellano TWO APPLICATIONS OF THE SYNCHROTRON RADIATION FOR CHARACTERIZATION OF HYDROGEN STORAGE AND HYDROGEN FUEL CELL MATERIALS ……………………………………………………………………..135 Karina Suárez Alcántara
UNPA MESYRUM 2014
15
Synchrotron Radiation applications in Life Sciences Andrea Lausi
Elettra Sincrotrone Trieste, Italia.
[email protected] Abstract Elettra is one of the first 3rd generation storage rings, recently upgraded to routinely operate in top-up mode at both 2.0 and 2.4 GeV. The facility hosts four dedicated beamlines for crystallography, two open to the users and two under construction, and expected to be ready for public use in 2015. In service since 1994, XRD1 is a general purpose diffraction beamline. The light source for this wide (4-21 keV) energy range beamline is a permanent magnet wiggler. XRD1 covers experiments ranging from grazing incidence X-ray diffraction to macromolecular crystallography, from industrial applications of powder diffraction to X-ray phasing with long wavelengths. The bending magnet powder diffraction beamline MCX has been open to users since 2009, with a focus on microstructural investigations and studies under non-ambient conditions. A superconducting wiggler delivers a high photon flux to a new fully automated beamline dedicated to macromolecular crystallography and to a branch beamline hosting a high pressure powder X-ray diffraction station (both currently under construction). Users of the latter experimental station will have access to a specialized sample preparation laboratory, shared with the SISSI infrared beamline. A high throughput crystallization platform equipped with an imaging system for the remote viewing, evaluation and scoring of the macromolecular crystallization experiments, has also been established and is open to the user community.
UNPA MESYRUM 2014
16
Unmasking pathogenicity and virulence: A structural approach using synchrotron radiation
Federico M. Ruiz, Elena Santillana, Mercedes Spínola-Amilibia, Francisco Javier Medrano, Antonio Romero
Centro de Investigaciones Biológicas, CSIC, 28040-Madrid (Spain)
Email: [email protected]
Keywords: X-ray crystallography, protein structure, antibiotic resistance, protein secretion Abstract Infectious diseases are the leading cause of death worldwide and are a major challenge for public health. Despite recent advances in biochemical and structural studies of a series of pathogenic factors, a better understanding of targets implied in antibiotic resistance and microbial pathogenesis and how they are transferred is important to combat infectious diseases. Approaches to combat bacterial infection rely on the disruption of the bacteria growth cycle by preventing the synthesis and assembly of key components of bacterial processes or by inhibition of virulence traits [1]. Acinetobacter baumannii is the source of numerous nosocomial infections in humans and therefore deserves close attention due to the existence of multidrug resistant strains. These multidrug resistance (MDR) strains are isolated from nosocomial infections mainly from immunocompromised patients hospitalized in intensive care units. We have been able to characterize a series of proteins involved in human infections at atomic resolution using synchrotron radiation, in order to understand the mechanisms of pathogenicity of this opportunistic human pathogen. We have applied X-ray crystallography and other biophysical techniques to analyze the role of the selected targets in bacterial infection and antibiotic resistance. We will show the structures of several targets going from periplasmic and cell wall proteins namely, b-lactamases (Figure 1) [2], penicillin binding protein 2 (PBP2) and porins (Omp33-36 and OprD-like porin) [3] from two different multiresistant clinical strains of A. baumannii, to more specialized secretion systems (tssB, tssC and tssD, components of the T6SS machinery) (Figure 2) [4]. It is foreseeable that the structural information obtained will provide new leads to develop novel therapeutic approaches to combat bacterial infection.
UNPA MESYRUM 2014
17
Soft X-ray Ptychography for Nano-Materials Research
David A. Shapiro1, Young-Sang Yu2, Maryam Farmand1, Tolek Tyliszczak1, Jordi Cabana3, A.L. David Kilcoyne1, Filipe Maia4, Stefano Marchesini1, Tony Warwick1, and Howard A. Padmore1
1 Advanced Light Source, LBNL, Berkeley, CA 94720
2 Environmental Energy Technologies Division, LBNL, Berkeley, CA 94720
3 Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607
4 Laboratory of Molecular Biophysics, Uppsala University, SE-751 24 Uppsala, Sweden
Email: [email protected] Keywords: X-ray microscopy, ptychography, x-ray diffraction The Advanced Light Source has demonstrated the highest resolution x-ray microscopy ever achieved through the use of soft x-ray ptychography [1,2]. We demonstrate 3 nm spatial resolution while imaging a test object with 1500 eV x-rays and quantify the resolution enhancement that comes with increased x-ray exposure and improved reconstruction algorithms [3]. We apply our method to the study of lithium intercalation pathways in nano-particles of LiFePO4, a material of broad technological and fundamental interest in electrochemical energy storage [4]. Our soft x-ray ptychographic images show dramatically higher spatial resolution and contrast compared to conventional state-of-the-art scanning transmission microscopy. Component maps calculated from the full complex refractive index show enhanced chemical contrast which elucidates a strong correlation between structural defects and chemical phase propagation that is not accessible by other means. Soft x-ray ptychography at the new COSMIC beamline is set to revolutionize the study of chemistry at the nanoscale.
Figure 1: Soft x-ray spectro-ptychography of partially delithiated LiFePO4. (a) Standard STXM image with a 25 nm optic at 710 eV showing maximum contrast between FePO4 and LiFePO4. (b) Ptychography absorption image at 710 eV using a 60 nm optic. Red arrows point to surface cracks which reveal an unreacted domain below. (c) Ptychography phase image at 709.2 eV (d) Ptychographic chemical mapping using a full energy image stack [2]. Scale bar is 100 nm.
UNPA MESYRUM 2014
18
References [1] P. Thibault, et al, Science, 321, 379 (2008) [2] D. A. Shapiro et al, Nature Photonics, 8, 764-769 (2014) [3] S. Marchesini, et al, Inverse Problems, 29 (11), 115009 (2013) [4] B. Kang and G. Ceder, Nature, 458, 190-193 (2009)
UNPA MESYRUM 2014
19
The ID21 beamline at the European Synchrotron Radiation Facility: a multi-analytical platform for micro-spectroscopic analyses
Hiram Castillo-Michela, Marine Cottea,b, Murielle Saloméa, Barbara Fayarda, Emiline Pouyeta, Camille Rivarda,
David Bugnazeta, Eric Gagliardinia, Gilles Berruyera, Jean Susinia
a European Synchrotron Radiation Facility, BP220 – F-38000 Grenoble, France
b C2RMF, CNRS UMR 171, Palais du Louvre, 14, Quai F. Mitterrand, F-75001 Paris, France Email: [email protected]
Keywords : X-ray, speciation, infrared.
The ID21 ESRF is a beamline dedicated to X-ray and FTIR micro-spectroscopy. Localization and speciation of trace elements is primarily done using micro-X-ray fluorescence (µXRF) and micro X-ray absorption spectroscopy (µ-XANES) in the tender X-ray domain (2-9.2 keV). ID-21 has sensitivity in the low ppm range and allows localization with a sub-micron beam of various elements. The scanning X-ray microscope (SXM) is designed to cover a relatively wide range of elements of interest in nanotoxicology.
The SXM offers a very high versatility in terms of focusing optics, detection and sample environment. The
X-ray beam spot size can be tuned from macro (200 µm) to sub-micro (~500 nm), which then allows localization of trace elements at subcellular level. A large panel of complementary detectors is available and provides: high sensitivity, high throughput, or high spectral resolution, which enables the collection of µ-XRF and µ-XANES spectra on a large variety of biologically relevant samples. The samples can be studied in various conditions (room temperature, cryo, wet cells). In particular, the analysis in cryogenic conditions allow the study of frozen hydrated specimens (cells and cryo-sectioned tissues) preventing elemental redistribution and minimizing radiation damage. Due to the penetration depth of X-rays ultramicrotome sectioning is not required like in transmission electron microscopy and frozen hydrated cells can be studied without sectioning.
The X-ray scanning microscope is therefore highly appropriate for in-situ studies of trace metals used in
nanotechnology such as Ti, Cr, Fe, Co, Ni, Cd, Ce, Ag and Cu, and gives simultaneously access to mapping and speciation of lighter elements such as P, S, Ca which can be involved in fixation/elimination mechanisms. This combined approach allows studying the chemical modifications of NPs in biological systems down to sub-cellular level. Additionally, ID21 has a SR-based FTIR end-station that can provide complementary molecular mapping, a recently developed in vacuum full-field XANES end-station, and a µXRD side branch under construction.
In summary, ID21 offers a multimodal set up of state-of-the-art techniques for micro-spectroscopies in life
sciences [1-4]. Results obtained at the beamline in the study of Ti, Ce and Ag nanoparticles will be discussed. [1] Sarret et al. Canadian Journal of Chemistry, 85 2007 p.738. [2] Lin et al. 2011. Environmental Science and Technology, 45 2011 p. 2360. [3] Isaure et al. Geochimica et Cosmochimica Acta, 74 2010 p. 5817. [4] Bohic et al. Journal of structural biology, 177 2012 p. 248.
UNPA MESYRUM 2014
20
Figure 1. The ID21 X-ray microscopy beamline at the ESRF houses two microscopes: a Scanning X-ray Microscope (SXM) and an infrared microscope (SR-FTIR microscope).
UNPA MESYRUM 2014
21
Synchrotron Radiation applications in Life Sciences
Vivian Stojanoff
Brookhaven National Laboratory, National Synchrotron Light Source (NSLS) USA. Bldg725D, Upton NY 11973 USA
Keywords: SAXS Abstract Embracing a wide range of the electromagnetic spectrum, from infrared light to X-rays synchrotron radiation sources provide the researcher with a set of non-destructive methods and techniques suitable to unveil the mysteries of life. Although several of these methods, such as, Fourier transform infrared spectroscopy (FTIR) and small angle X-ray scattering (SAXS) are available in the laboratory synchrotron sources provide: tunability, choice of wavelength; higher signal-to-noise, the higher intensities of synchrotron sources allow the study of more dilute samples; better spatial resolution, synchrotron light sources are generally better collimated compared to sources found in the research laboratory; and faster analysis, due to the higher intensity of the source. The wide selection of non-destructive methods and techniques available that are particularly well adapted to the analysis of the molecular structure, chemical analysis, and imaging will be revised in light of specific applications.
UNPA MESYRUM 2014
22
Current developments for high pressure diffraction studies using synchrotron radiation
Bjoern Winkler a
a Institute of Geoscience, Goethe University, Frankfurt, D-60438, Germany Email: [email protected]
Keywords: high pressure, diamond anvil cell, laser heating Due to recent advances in technical developments at beamlines dedicated to high pressure diffraction studies (e.g. ID09 and ID27 at the European Synchrotron Radiation Facility, ESRF, in Grenoble, and the “extreme conditions beamline” P02.2 at PETRA III in Hamburg) high pressure studies using diamond anvil cells now offer unprecedented opportunities to deepen our understanding of the behavior and properties of matter at very high pressures and temperatures. In my contribution I will describe the current set-up of the laser-heating system at the extreme conditions beamline at PETRA III. I will give examples of recent diffraction studies in the laser-heated DAC, where powders, single crystals, and poorly crystalline and amorphous materials have been investigated. Examples will include studies aimed to synthesize new compounds, such as transition metal-carbides, -nitrides and borides [1,2]. These studies are based on powder diffraction. I will also show examples where single crystal studies have been used to characterize pressure-induced spin transitions [3] and studies, where the total scattering approach with a pair distribution function analysis has been employed to investigate decomposition and polymerization reactions [4,5]. The extreme conditions station at PETRA III is continuously being upgraded and I will present the latest developments. A recent addition, which now will become available for external users, is a micro-fluorescence set-up. In the coming year, we will also perform “pink beam”-experiments, to explore the feasibility of following fast structural changes at high pressures and temperatures. Finally, I will give an outlook on current progress in detector technology relevant for high pressure diffraction studies at high photon energies. Specifically, the use of high-Z sensors, such as GaAs, in combination with a CMOS pixel detector readout chip (such as Medipix3), will significantly improve diffraction experiments at high photon energies. Such detectors will become available for experiments at the “extreme conditions beamline” at PETRA III in the near future. Acknowledgements I gratefully acknowledge the financial support of the DFG (projects Wi1232, SPP 1236) and the BMBF (projects 05K10RFA, 05KS7RF1, 05K13RF1, 05K13RF2), which have been essential to establish the laser-heating system, the micro-fluorescence detector, and the planned detector upgrade in Hamburg. I wish to thank the beam line managers, H.-P Liermann (Hamburg), A. Bosak, M. Krisch, M. Hanfland (ESRF) and M Kunz (ALS) and their teams. This work is the result of the efforts by all members, current and past, of the Frankfurt crystallography group, but especially those which have performed the majority of the experiments (L. Bayarjargal, A. Friedrich, E. A. Juarez-Arellano (now in Papaloapan), W. Morgenroth, and N. Rademacher). [1] A. Friedrich, B. Winkler, E. A. Juarez-Arellano, L. Bayarjargal. Materials 4 (2011) 1648-1692. [2] E. A. Juarez-Arellano, B Winkler, A. Friedrich, L. Bayarjargal, W. Morgenroth, M. Kunz, V. Milman. Solid
State Sciences 25 (2013) 85-92. [3] A. Friedrich, B. Winkler, W. Morgenroth, J. Ruiz-Fuertes, M. Koch-Müller, D. Rhede, V. Milman. Phys.
Rev. B 90 (2014) 094105 .[4] N. Rademacher, L. Bayarjargal, A. Friedrich, W. Morgenroth, M. Avalos-Borja, S.C. Vogel, Th. Proffen, B.
Winkler, J. Appl. Cryst. 44 (2011) 820 [5] N. Rademacher, L. Bayarjargal, W. Morgenroth, B. Winkler, J. Ciezak-Jenkins, I. G. Batyrev, V. Milman.
Chemistry 20 (2014) 11531-9
UNPA MESYRUM 2014
23
The ALBA synchrotron light source
Gastón García López a
a ALBA synchrotron light source, Cerdanyola del Vallès, 08290, Spain Email: [email protected]
Keywords: facility, construction, installation, operation, beamlines ALBA [1] is a third generation synchrotron light source, recently come into operation, located in Spain. A historical perspective of the main key aspects of the project is presented in this work, with the aim of giving an overview of the project, including its present status and prospects. Installing a new facility of this type in Spain was an unprecedented challenge, which may well serve as a reference [2]. Starting with a chronological review of the different phases of the project, the talk will pay special attention to some relevant decisions taken during the complex installation process. Some emphasis is made on the key decision of setting forward the project of a collaborative beamline at the European Synchrotron Radiation Facility (ESRF), at a very early stage of the project: this choice allowed for obtaining very relevant management experience, training Spanish instrumentalists, and fostering the growth of the Spanish user community. A motivation as to why a project like ALBA is justified will be argued, with a specific statement on the synergies to be created with science-driven industry. The civil works construction is an extremely relevant aspect, since buildings and conventional installations should be taken as an integral part of the scientific instrument. Therefore the main requirements and constraints will briefly be addressed and the construction sequence revised. The main aspects of the accelerator complex [3] will also be described briefly. ALBA has at the moment seven beamlines in operation (phase 1), plus two in construction (the so-called phase 2). Furthermore, a phase 3 set of beamlines is being refined with the aim of securing funding for the expansion of the lab from 2015 onwards. The beamlines to be briefly presented span from infrared to hard X-rays and deal with areas such as: bioscience, materials science, condensed matter physics, nanoscience and chemistry among others. ALBA phase 1 beamlines came into operation gradually during year 2012. The first experiment with official users (that is, with beamtime allocated via a public call and peer-review selection) started on 7th May 2012 at the BL29 BOREAS beamline, dedicated to X-ray Magnetic Circular Dichroism technique. The experiment, focused on characterizing magnetic nanoparticles embedded in a high-Tc superconducting material, was the first of a long series continuing until today, with three user cycles (corresponding to their respective public calls) and a fourth call finishing evaluation within the last few weeks, to allocate beamtime during the first half of 2015. A few examples of experiments will be mentioned and briefly described, in order to get a feeling of the very diverse fields implied and the type of science therein. Some statistics of user access complement the information on specific experiment examples. ALBA operates yearly 5000 to 6000 hours [4], gradually ramping up towards the latter number. An example of operations calendar will be shown to illustrate the way to organize operations and make them compatible with the necessary maintenance and resource-driven constraints. As mentioned above in this abstract, ALBA is at the moment bulding two phase 2 beamlines. A schedule overview of both is given, in order to get an overall picture of the process involved.
UNPA MESYRUM 2014
24
Finally some considerations are given to the importance of outreach and education policies, which make the science and technology work done at the facility better known to present and future taxpayers (and potentially future scientists). The talk will finish with some considerations about the main issues to be considered during the next few years of the ALBA project. References: [1] www.albasynchrotron.es [2] J. Bordas et al., NIM A 543 (2005) 28-34. [3] M. Pont, in Proceedings of the 3rd International Particle Accelerator Conference (2012) 1659-1661. [4] http://www.cells.es/en/en/media/corporate-publication.
UNPA MESYRUM 2014
25
SSRL Now and in the Future Robert Hettela
a SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
Email: [email protected]
Keywords: (storage ring light source, synchrotron radiation science program) The Stanford Synchrotron Radiation Lightsource (SSRL), located at the SLAC National Accelerator Laboratory, employs the 3-GeV, 500-mA SPEAR3 storage ring to provide X-rays for 33 experimental stations, with more planned for the future. SSRL supports world-class science in targeted áreas, including materials by design, emergent behavior, complex bio-processes and molecular environmental and interface science. Recent developments of the SPEAR3 accelerator include a short-bunch operation mode and an emittance reduction program. The future of SSRL, in a world where very low emttance, 4th generation storage rings are emerging, includes its becoming closer connected to the LCLS X-ray FEL science program as a synergistic, complementary research facility, and portentially the farther future migtation to the diffraction-limited PEP-X storage ring. An overview of the SSRL facility and science program, now and with potential future developments, will be presented.
UNPA MESYRUM 2014
26
Presentation of the Synchrotron Users Network (RedTULS)
Guadalupe de la Rosa a
a Universidad de Guanajuato Campus León. Loma del Bosque 103, León, Gto. C.P. 37150 Email: [email protected]
Keywords: Synchrotron users, Mexico, Users Network Abstract In Mexico, about 140 researchers and students have take advantage of Synchrotron Radiation techniques. This state of the art tools are extremely useful to obtain information on the matter that cannot be obtained using traditional techniques. In 2010, a group of experts in the area of High Energy Physics suggested the creation of a network to strengthen collaboration among Mexican synchrotron users. This collaboration will eventually impact in the generation of more specialized human resource that in the near future will be in charge of a Mexican Synchrotron. The aim of this network is to perform activities directed to promote the use of synchrotron techniques in order to increase our scientific and technical capabilities. With this, we as a country, will be more competitive. We also intent to motivate the productive sector to use these tools as a way to improve processes, and materials. These activities will eventually impact in the generation of employment and wealth in our country. Among the Institutions participating in this group are:
� Universidad Nacional Autónoma de México � Universidad Autónoma de Zacatecas � Universidad Autónoma de San Luis Potosí � Instituto Tecnológico de Celaya � Universidad del Papaloapan � Universidad de Guanajuato � Universidad Autónoma del Estado de Morelos � CINVESTAV � Universidad Autónoma de Ciudad Juárez
� Universidad Autónoma de Chiapas � Instituto Tecnológico de Oaxaca � CCADET � IPN � CICATA � CIATEJ � IPICYT � CIDETEQ � Instituto Mexicano del Petróleo � Universidad de Guadalajara
UNPA MESYRUM 2014
27
Applications of Synchrotron Radiation to Solve Complex Structural Problems
Edilso Reguera
Center for Applied Science and Advanced Technology, Legaria Unit, National Polytechnic Institute, Mexico Email: [email protected]
Keywords: High-Resolution X-ray powder diffraction; phase transitions; Crystal structure solution and refinement X-ray diffraction (XRD) pattern from a single crystal is the ideal method to solve the crystal structure of new materials. The crystal structure and the recorded XRD pattern has a univocal correspondence; the pattern corresponds to the Fourier Transform for the crystal structure in the inverse space. From the inverse Fourier Transform of the experimental pattern, the structural model (in the direct space) to be refined can be obtained. This is a 3D ↔ 3D problem with unique solution. The only limitation of this method for structural studies is the phase problem. Because the experiment only determines intensities, the phase remains undetermined. The crystallography from single crystals is a well-established technique for structural studies and there are different approaches to overcome the phase problem. However, for only a small fraction of the new materials, probably below 5%, is possible the growth of single crystals with appropriate quality for structural studies. For the remaining cases (> 95%), the material crystal structure must be solved and refined from XRD powder patterns, where the experimental pattern is a projection of the 3D structure into 1D space (Bragg angle or interplanar d-distance). This is an ill-posed problem, without unique solution. Its solution requires of boundary conditions or availability of a priori information. Fortunately, spectroscopic techniques provide information on the coordination number, coordination geometry, nature and bond distances for the first and second neighbors, oxidation state and electronic configuration for the observed atom, presence of vacancies (occupation factor), number of non-equivalent structural sites, nature and geometry of the involved molecular blocks for the case of organic and hybrid inorganic-organic solids, among other parameters. All these information has local character but it can be used to restrict the number of possible solutions from the mentioned ill-posed problem and also to validate the refined structural models. From an appropriate combination of spectroscopic and powder XRD data, in principle, any structural problem could be solved. A Synchrotron is machine that produces high intensity light for the entire electromagnetic spectral region. From this fact, it can be used to do both, spectroscopic and diffraction experiments under both, high intensity and high resolution conditions. The large amount of structural data collected can then be combined for the crystal structure solution and refinement. Such methodology is applicable to a wide variety of materials. When several structural models (space group) are possible, a usual situation from structural studies from XRD powder patterns, the a priori available spectroscopic data help to discriminate between them in order to reduce the number of models to be tested. This is particularly important when light atoms and molecular blocks are involved, where powder XRD data have certain limitations to obtain the appropriate structural model. The potentialities of powder XRD technique for the crystal structure solution and refinement of complex materials are significantly improved when a priori information is incorporated to the problem to be solved. In this contribution, the combined use of spectroscopic techniques and powder XRD data is illustrated through the structural study of series of coordination compounds, metal-organic and hybrid inorganic-organic type solids. A brief summary on the scope of different spectroscopic techniques in that sense is also discussed. Molecular materials are receiving an increasing attention in the last years by their interesting physical and functional properties and not always high-quality single crystals are obtained to solve the structural problem from single crystal XRD data. Many of these materials crystallize as fine powders, and their crystal structure must be solved and refined from powder XRD data.
UNPA MESYRUM 2014
28
In this talk, the ideas mentioned above are illustrated and discussed with examples of crystal structure solution and refinement from XRD data collected at XPD beamline of the LNLS synchrotron radiation facility (Brazil). The structural information derived from XRD patterns is combined with spectroscopic data from Mossbauer, CPMASNMR, UV-vis, IR and Raman spectroscopies to solve the crystal structural of materials based on coordination polymers and hybrid inorganic-organic materials. Such spectroscopic information is then used to validate the refined structural model. Figure corresponds to a typical example, particularly the vacancy distribution in Prussian blue analogues. Additional details on the studied materials and on the used methodology are available from the references given below.
a)
b)
c)
d)
Figure: Vacancy distribution in Prussian blue analogues. A) High intensity XRD powder pattern; b) atomic packing within the unit cell; c) Mossbauer spectra; d) Hydrogen storage capacity.
UNPA MESYRUM 2014
29
References [1] J. Rodríguez-Hernández, A. A. Lemus-Santana, J. Ortiz-López, S. Jiménez-Sandoval, E. Reguera; Low
temperature structural transformation in T[Ni(CN)4].xpyz with x = 1, 2; T = Mn, Co, Ni, Zn, Cd; pyz = pyrazine;, Journal of Solid State Chemistry 183(2010) 105-113
[2] J. Jiménez-Gallegos, J. Rodríguez-Hernández, H. Yee-Madeira, E. Reguera; Structure of porous copper
Prussian blue analogues: Nature of their high H2 storage capacity. J. Phys. Chem. C 114 (2010) 5043–5048 [3] M. González, A. A. Lemus-Santana, J. Rodríguez-Hernández, M. Knobel, E. Reguera; Pi-Pi Interactions and Magnetic Properties in a Series of Hybrid Inorganic-Organic Crystals; J. Solid State Chem. 197 (2013) 317–322
UNPA MESYRUM 2014
30
The Early Days of Synchrotron Radiation in the World and in Mexico
José Jiménez-Mier a. a Instituto de Ciencias Nucleares, UNAM, México DF, Mexico.
Email: [email protected] Keywords: Synchrotron radiation history. Gas phase photoelectron spectrometry. Photon-in photon-out experiments Slightly more than fifty years have passed since the publication of the seminal article of Madden and Codling [1] in which they reported series of autoionizing resonances in noble gases. In this talk some of the events related to the initial work using synchrotron radiation and its protagonists are presented. It includes the problem of the highest electron kinetic energy attainable at a synchrotron and its complete solution by Julian Schwinger in 1946 [2]. In an extended paper published later [3], Schwinger presented a full calculation of the properties of synchrotron radiation. Then the earlier observations of synchrotron radiation [4] and the first measurements of its properties by Toumbulian and Hartman [5] are discussed. At Later on, proposals to use synchrotron radiation to study the electronic structure of solids were made. In the early 60’s a group of bright scientists under the leadership of Ugo Fano gathered together at the National Bureau of Standards (predecessor of NIST) to perform a series of groundbreaking gas-phase experiments. Superficial references to subsequent synchrotron radiation work in Europe and Japan are also made. The contribution of Ednor Rowe and its brainchild Tantalus I to the idea of dedicated synchrotron radiation facilities is also reviewed. In the second part of the talk a review of the early work by Mexican researchers in synchrotron radiation sources is made. They include fluorescence and photoelectron spectrometry work of gas-phase samples at SURF-II and Aladdin, and ARPES work of solid samples and surfaces in Aladdin. A comparison between fluorescence and photoelectron experiments and their complementarity in the so-called complete or perfect gas phase photoionization experiments performed in the 90’s is made. A review of the use of photon-in photon-out experiments to study the electronic structure of transition metal compounds. This collage is finished with a brief digression is made about the prospects of building a synchrotron radiation source in Mexico. [1] R. P. Madden and K. Codling, New Autoionizing Energy Levels in He, Ne and Ar, Phys. Rev. Lett 10, 516
(1963). [2] J. Schwinger, Electron Radiation in High Energy Accelerators, Phys. Rev. 70, 798 (1946). [3] J. Schwinger, On the Classical Radiation of Accelerated Electrons, Phys. Rev. 75, 1912 (1949). [4] F. R. Elder, M. Gurewitsch, R. V. Langmuir, and H. C. Pollock, Radiation from Electrons in a Synchrotron,
Phys. Rev. 71, 829 (1947). [5] D.H. Tomboulian and P.L. Hartman, Spectral and Angular Distribution of Ultraviolet Radiation from the
300-Mev Cornell Synchrotron, Phys. Rev. 102, 1423 (1956).
UNPA MESYRUM 2014
31
Non-‐conventional techniques for protein crystallization and crystal growth
Abel Moreno Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Av. Universidad 3000, Ciudad Universitaria, C.P. 04510. Apdo. Postal 70250, México, D.F., México.
Email: [email protected]
Keywords: Electric field protein crystallization, vapor diffusion.
Abstract: New strategies for protein crystallization either in solution or in gel using different devices that control the transport phenomena and crystal growth are reviewed [1]. A new easy-‐to-‐use device has been designed and implemented for electric-‐induced protein crystallization in a batch or vapor diffusion configurations. The device controls the crystal nucleation by means of the electrical current and also favors crystal growth due to its vapor diffusion set-‐up [2]. Other strategies such as the influence of magnetic field or temperature during protein crystallization will also be discussed. The crystal quality of glucose isomerase grown at different temperatures was evaluated using synchrotron radiation. Additionally, we applied a magnetic force of 11.75 Tesla (500 MHz) for the length of the nucleation period for model and novel proteins using a classical spectroscopy NMR magnet. As evidenced from these present results the use of a magnetic field on the protein crystals resulted in the orientation of these crystals along the c axis, which corresponded to the direction of the magnetic field. Additionally, the use of the hydrogel together with magnetic force resulted in individual larger crystals with better structural quality compared to the crystals observed in the absence of magnetic field.
References
[1] Gil-‐Alvaradejo, G., Ruiz-‐Arellano, R. R., Owen, C., Rodriguez-‐Romero, A., Rudino-‐Pinera, E., Antwi, M. K., Stojanoff, V. & Moreno, A. Novel Protein Crystal Growth Electrochemical Cell for Applications in X-‐Ray Diffraction and Atomic Force Microscopy. Crystal Growth & Design 11, (2011) 3917-‐3922. [2] Flores-‐Hérnandez, E., Stojanoff, V., Arreguín-‐Espinosa, R., Moreno, A., and Sánchez-‐Puig, N. An electrically assisted device for protein crystallization in a vapor diffusion set-‐up. Journal of Applied Crystallography 46 (2013) 832-‐824.
UNPA MESYRUM 2014
32
Synchrotron light diffraction and scattering in functional materials
Luis Fuentes-Monteroa, María E. Fuentes-Monterob, María E. Montero-Cabrerac and Luis E. Fuentes-Cobas c
aDiamond Light Source Ltd, Didcot, OX11 0DE, United Kingdom b Universidad Autónoma de Chihuahua, Chihuahua, 31000, México
cCentro de Investigación en Materiales Avanzados, S.C., Chihuahua, 31109, México Email: [email protected]
Keywords: high-resolution x-ray diffraction, two-dimensional x-ray scattering, texture, multiferroics
A brief description of the state of the artof polycrystal structure analysis by synchrotron light diffraction and scattering is presented. Recent contributions by our group in the fields of θ-2θ powder diffraction and two-dimensional (2D) diffraction-scattering are divulged. Case studies, linked with ferroic materials, are discussed.
Extreme high brilliances of the x-rays available at synchrotrons allow researchers to use remarkably intense
and monochromatic beams and so to explore fine but important structural details of the generality of materials. By careful analysis of θ-2θ diffraction peaks splitting, our group has characterized subtle, conflicting or non-previously reported, symmetry break-downs in ferroic materials. Experiments with 2D detectors have enabled the investigation of intensities distributions in reciprocal space along sharp diffraction peaks from textured polycrystals as well as inside diffuse scattering zones caused by strained and/or nano-sized objects
. The field of functional materials analysis by synchrotron light diffraction and scattering is described in [1]. The case of lead-free ferroelectric ceramic 0.96(Bi0.5Na0.5)TiO3 – 0.04BaTiO3 (BNBT4) is discussed in [2]. A
wide angular range diffraction pattern was measured in high resolution configuration, with emphasis on trustable counting stastistics in the high-Q interval. The experiment was performed at beamline MCX of the Elettra synchrotron. Figure 1 shows a general view of the experimental diffraction pattern. Figure 2 represents schematically the particular feature of the performed experiment, exploring diffraction regions far from the reciprocal origin. Figure 3 shows in detail the high-Q region of the diffraction pattern. Data were processed by means of program FULLPROF [3]. Monoclinic Cc and rhombohedral R3c structural models were tried as primary phases. The obtained experimental results are incompatible with the monoclinic model and clearly favor the rhombohedral symmetry (Figure 4). In the Glazer representation [4], perovskite octahedra perform a-a-a- antiphase tilting.
2D detection experiments for investigation of diffuse scattering by ferroelectric nano-dots and Debye-rings
anisotropies due to textured thin films are reported respectively in [5] and [6]. The grazing incidence scattering work performed by Calzadaet al [5] detects and characterizes PbTiO3nano-
dots starting from diffuse scattering partly overlapped with sharp peaks from the polycrystalline substrate. The experiment was executed at beamline 11-3 of the Stanford Synchrotron Radiation Lightsource (SSRL). The PbTiO3nano-dots were found to be strained.
The paper by Pérez-Mezcua et al [6] reports the investigation, also made at SSRL beamline 11-3, of thin layers
formed by 0.90(Bi0.5Na0.5)TiO3-0.10BaTiO3 (BNBT10) textured nano-rods. Figure 5 shows the 2D diffraction pattern with the intensity distribution along a representative Debye ring. To characterize the nano-crystal orientation distribution, program ANAELU [7] (developed by our group) was employed. Figure 6 shows the answer to the associated texture problem: the symmetry axis inverse pole figure. The preferred orientation along the sample axis is [1, 1, 0] and the distribution width is 25°.
UNPA MESYRUM 2014
33
Acknowledgements: Reported research has been founded by Project CONACYT-CNPQ 174391
“MultiferroicosNanoestructurados”. Access to Stanford (SSRL) and Elettra Sincrotrone Trieste facilities is strongly recognized.
[1]L. Fuentes, in: L. Pardo, J. Ricote (Eds.), Multifunctional Polycrystalline Ferroelectric Materials, Springer, Dordrecht, 2011, p. 217. [2] L. Fuentes-Cobas, L. Pardo, M. E. Montero-Cabrera J. R. Plaisier, A. García, K. Brebøl,E. Mercadelli, C. Galassi. Crystal Research and Technology 49 (2014) 190–194. [3] J. Rodríguez-Carvajal. Physica B 192 (1993) 55-69. [4] A. Glazer. Acta CrystallographicaB28 (1972), 3384-3392. [5] M.L. Calzada, M Torres, L E Fuentes-Cobas, A Mehta, J Ricote, L Pardo. Nanotechnology18 (2007) 375603 (1-8). [6] D. Pérez-Mezcua, R. Sirera, I. Bretos, J. Ricote, R. Jimenez, L.Fuentes-Cobas, R. Escobar-Galindo, D. Chateigner, M. L. Calzada. J. Amer. Ceram. Soc. 97 (2014) 1269–1275. [7] L. Fuentes-Montero, M. E. Montero-Cabrera, L. Fuentes-Cobas. J. Appl. Cryst. 44 (2011) 241-246. Figure 1.High resolution XRD pattern of BNBT4.λ = 0.95 Å. Figure 2: Standard and “extended Q” limiting Elettra Sincrotrone Trieste, MCX beamline. spheres in reciprocal space.
UNPA MESYRUM 2014
34
Figure 3.High-Qrange in the diffraction pattern of Figure 1. Figure 4: BNBT4 crystal structure. Subtle anti- Comparison of rhombohedral R3c and monoclinic Ccmodels.phasea-a-a- tilting, of theperovskite octahedra. Figure 5.2D-XRD pattern of a BNBT10.Thin film.λ = 0.98 Å. Figure 6: Characteristic inverse pole figure. Stanford Synchrotron Radiation Lightsource, Beamline 11-3. 2D-XRD modeled by ANAELU.
UNPA MESYRUM 2014
35
Application of the X-ray absorption fine structure (XAFS) in functional and environmental materials
Isaí Castillo-Sandovala, Edgar Macías-Ríosa,Iván J. Carreño-Márqueza, Luis E. Fuentes-Cobasa,
María E. Fuentes-Monterob, Hilda E. Esparza Poncea,Maria E. Montero-Cabreraa
aCentro de Investigación en Materiales Avanzados, Chihuahua, 31109, México. bFacultad de Ciencias Químicas, Universidad Autónoma de Chihuahua, Chihuahua, 31000, México
Email: [email protected]
Keywords: Fe-Cr maghemite, XANES, EXAFS, Naica, pre-edge,µ-XAFS
X-ray absorption fine structure (XAFS) contributes towards understanding functional materials and environmental samples because necessarily targets a specific chemical element. X-ray absorption near edge structure (XANES) helps identify phases and oxidation states. In the extended region (EXAFS) it allows clarifying configurations and angles between the crystallographic directions. Of particular interest is the possibility of tuning the experiment on several elements in the same sample, allowing better elucidate the interatomic distances and order-disorder situations.
The inorganic solid solutionγ-Fe2-xCrxO3, maghemite for x=0.75, 1 and 1.25, was studied by X-ray absorption
fine structure (XAFS) of K-absorption edge of two elements and by synchrotron radiation X-ray diffraction (XRD).
At first, high-resolution XRD patterns were processed by means of the Rietveld method, using Fullprof [1]. In
Rietveld refinements, the ordered/disordered degree of the considered solution is indiscernible in cases of atoms being neighbors in the Periodic Table. Crystallographic interpretation of magnetic and ferroelectric phenomena is shortened by this limitation.
Double-element XAFS analysis was applied to clarify, via short-range structure characterization, the nature of
the investigated system. XAFS would confirm or reject the random character of the solution. Measurements were performed at the Stanford Synchrotron Radiation Lightsource at room temperature, at beam lines 2-3 and 4-3.Athena and Artemis codes as interfaces for IFEFFIT [2] and FEFF8.4 [3] codes were employed for XAFS spectra interpretation.
γ-Fe2-xCrxO3 was investigated by XAFS in both Fe and Cr K-edges. Pre-edge decomposition and theoretical
modeling of XANES transitions were performed.Interatomic distances were determinedfor x=1, by the fitting of average spectra in the EXAFS region in both edges simultaneously.In the model the Cr3+ as cation t2g3, occupies only the octahedral positions, while Fe3+, a cation t2g3 eg2 in a high-spin configuration, occupies both octahedral and tetrahedral positions. By analysis of the Cr K-edge XANES, it has been confirmed that Cr is located in an octahedral environment (Figure 1). These considerations forced fit the spectra with the central atom of Fe being able to occupy two different positions, each with a weight adjustment, while Cr occupies only one.The results of fitting the experimental spectra with theoretical standards made it possible to show that the cationvacancies tend to be located orderly within the structure of the iron-chromium maghemite (FeCrO3) at sites L2, L3, L5, L6, L8, L9, L11 and L12 (see Figure 2)[4].
Based on the treatment of experimental data fromCr oxides(Figure 3), the study of environmental samples is
presented.Arsenic assessment in soil, actinide ion sorption at the interphase solid/aqueous solutions, chromium removal through membranes, and many other subjects have been studied by means of XANES and EXAFS. Figure 4 shows the µ-XAFS spectra from the surface impurities of crystals from the Naica mine.Phases in trace amounts were identified.
UNPA MESYRUM 2014
36
Acknowledgements: Portions of this research were carried out at the Stanford Synchrotron Radiation
Lightsource, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. The SSRL Structural Molecular Biology Program is supported by the Department of Energy, Office of Biological and Environmental Research, and by the National Institutes of Health,National Center for Research Resources, Biomedical Technology Program. Support from CONACYT (Projects 46515 and 26040), is gratefully acknowledged.
[1] J. Rodríguez-Carvajal. Commission on Powder Diffraction Newsletter 26(2001)12–19. [2] B. Ravel and M. J. Newville. Synchotron Radiation12 (2005) 537-41. [3] J.J. Kas, J.J. Rehr, J.L. Glover, and C.T. Chantler. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 619 (2010) 28-32. [4] R. Grau-Crespo, A. Y. Al-Baitai, I. Saadoune, N. H. De Leeuw. Journal of Physics: Condensed Matter22(2010) 255401. [5]M. Wilke, F. Farges, P. E. Petit, G. E. Brown Jr.,F. Martin.American Mineralogist 86 (2001) 714–730.
Figure 1. Cr K-‐edge XANES. The first inflection of the main edge in maghemite samples are at 5998.2, 5999.4 and 5998.8 eV, for Cr contents x = 0.75, 1.00 and 1.25, respectively; and Cr2O3 and CrO2 are at 5999.4 and 6001.3, respectively. Also, the pre-‐edge peak is practically vanishing in maghemite spectra.
Figure 2. Models for EXAFS interpretation and vacancies occupation. Octahedral sites L1, L4, L7 and L10, shown in blue, are always occupied by either Cr3+ or Fe3+.
UNPA MESYRUM 2014
37
Figure 4.Comparison of Fe K-‐edge XANES spectra for the surface impurity of a selenite crystal with the iron standard. At right, XANES spectra of different minerals [5]presenting Fe3+ in 6-‐coordinated sites are shown, for identification of hematite impurities on the crystal surface.
Figure 3.Comparison of Cr K-‐edge XANES spectra for different compounds.Increasing oxidation statesare shown. First inflexion shifts to higher energies, as well as pre edge arearises, when increasesthe oxidation state.
UNPA MESYRUM 2014
38
The Mexican Synchrotron Project in Morelos
Matías F. Moreno Yntriago
Universidad Nacional Autónoma de México Instituto de Física
Circuito de la Investigación Científica Ciudad Universitaria CP 04510 México, D.F. Email: [email protected]
Keywords: Synchrotron Abstract. A review of the range and objectives of the Mexican State of Morelos to support a National Synchrotron Light Source is presented. After a brief historical introduction, I will focus on the span of the present project which is funded by a Conacyt-Morelos FOMIX (Joint Conacyt- Morelos State) fund.
UNPA MESYRUM 2014
39
X-ray absorption near edge spectroscopy as a tool determine atomic locals structure
Jose Mustre de León
Departamento de Física Aplicada, Cinvestav Mérida, Mérida, 97113, Mexico [email protected]
Keywords: XANES, dynamical lattice distortion, hydration shell of ions X-ray absorption Near Edge Structure (XANES) refers to the region of the x-ray absorption spectrum which is situated few electron volts above the absorption edge of a particular element. Usually this part of the x-ray absorption spectrum is used to infer qualitative information about the local electronic structure around the absorbing atom, e.g., formal valence. On the other hand the region of the x-ray absorption spectrum above 30-50 eV from the edge referred as extended x-ray absorption fine structure (EXAFS) is used to obtain in a straightforward manner information about the local atomic structure around an absorbing atom, e.g., coordination numbers, bond-length distance, and mean squared fluctuations about the average bond length. However, in certain cases, like highly disordered systems or ions in solution EXAFS can only provide information about the nearest neighbor coordination shell.[1, 2] In those systems a detailed interpretation of the XANES spectra can yield local atomic structural information not available using other spectroscopical techniques, like neutron diffraction, x-ray diffraction or EXAFS. Here we present two examples in which we can extract local atomic structural information by performing a comparison between ab-initio calculations of XANES spectra and experiment. The starting point of these calculations is a structural ansatz suggested by other structural studies or molecular dynamics simulations of the systems in question. The first example we present is the system PrNiO3, which belongs to the family of rare-earth nickelates, which exhibit a perovskite structure. This compound exhibits a simultaneous magnetic and metal-insulator transition (MIT) below ~115 K.[3] Since no structural transition had been observed across the metal insulator-transition, it was believed that the origin of this transition was electronic. However this presented a problem, since a giant negative isotopic effect had been observed in the MIT. A comparison between experimental and calculated XANES spectra shows that there is a local change of symmetry, from tetragonal system (Figure 1) at high temperatures to monoclinic at low temperatures. [4] These results suggest that this local structural change is dynamical and is a manifestation of polaronic behavior in these materials. As a second example we discuss the local atomic structure around arsenic ions in solution. Such information is important in order to understand the toxicity of arsenic at the molecular level. [5] XAFS measurements of acidic arsenic solutions indicate that arsenic appears as a cluster of As(OH)3 with As bonded to 3 OH radicals. The comparison of theoretically generated EXAFS and experiment, indicate that nearest neighbor structural configurations generated using ab-initio density functional theory calculations are not consistent with the experimental results, while configurations obtained from molecular dynamics simulations are consistent. These simulations also yield configurations, which include neighboring water molecule. The use of those configurations in ab-initio XANES calculations reproduces experimental results. [5] Such configurations have as a common element water molecules forming an irregular hexagonal array above the equatorial plane defined by AS-OH bonds, with three water molecules forming hydrogen bonds with the As(OH)3 cluster. This structural arrangement, known as clatharte structure (Figure 2) had been proposed as a possible structure that would cross the cell membrane, explaining the high toxicity of arsenic (III) in solution.[6] [1] P.J. Merkling, A. Muñoz-Páez, E. Sánchez, Exploring the Capabilities of X-ray Absorption Spectroscopy
for Determining the Structure of Electrolyte Solutions: Computed Spectra for Cr3+ or Rh3+ in Water Based on Molecular Dynamics. J. Am. Chem. Soc. 2002, 124, 10911-10920.
[2] J.M.Lozano, D.L. Clark, S.D. Conradson, C. Den Auwer, C. Fillaux, D. Guilaumont, D. Webster Keogh, J. Mustre de Leon, P.D.Palmer, E. Simoni, Influence of the local atomic structure in the X-ray absorption near edge spectroscopy of neptunium oxo ions. Phys. Chem. Chem. Phys, 2009, 11, 10396.
UNPA MESYRUM 2014
40
[3] M. Medarde, P. Lacorre, K. Conder, F. Fauth, and A. Furrer, GiantO16-O18 Isotope Effect on the Metal-Insulator Transition of RNiO3Perovskites (R=Rare Earth), Phys. Rev. Lett. 80, 2397, 1998. [4] M. Acosta-Alejandro, J. Mustre de León, M. Medarde, Ph. Lacorre, K. Konder, P. Montano, Local lattice structure change in PrNiO3 across the metal-insulator transition: X-ray absorption near-edge structure spectroscopy and ab initio calculations, Phys. Rev. B, 77, 085107, (2008). [5] R.Wysocki, C. Chery, D.Wawrzycka, M.V. Hulle, R.Cornelis, J. Thevelin, M. Tamas. The glycerol channel
Fps1p mediates the uptake of arsenic and antimonite in Saccharomyces cerevisiae. Mol. Microbiol. 2001, 40, 1391-1401.
[6] J. Canche-Tello, M. Cristina Vargas, J. Hernández-Cobos, I. Ortega-Blake, A. Leclerq, P.L. Solari, C. Den Auwer, J. Mustre de Leon, Interpretation of X-ray Absorption Spectra of As(III) in solution using Monte Carlo simmulations. Journal of Phys. Chem. (2014). http://dx.doi.org/10.1021/jp5061232
Figure 1. Monoclinic structure (low temperature) of PrNiO3 (upper pannel), Orthorhombic structure (high temperature) of PrNiO3.
Figure 2. Local atomic structure of hydration sphere around As(OH)3 cluster.
UNPA MESYRUM 2014
41
First direct observation of single magnons by oxygen K-edge RIXS on iridates.
Paul Olalde-Velasco a, Yaobo Huang a, Valentina Bisogni a, Jonathan Pelliciari a, Marcus Dantz a, Sara Fatale b, James Vale c, Jun Miyawaki d,e, Yoshihisa Harada d,e, Alessandro Nicolau f, Sorin Chiuzbăian g, Desmond
McMorrow c, Dharmalingam Prabhakaran h, Andrew Boothroyd h, Johan Chang b, Henrick Rønnow b, Vladimir Strokov a and Thorsten Schmitt a.
a Paul Scherrer Institut, Swiss Light Source, CH-5232 Villigen PSI, Switzerland.
b Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Switzerland.
c London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.
d Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8581, Japan. e Synchrotron Radiation Research Organization, University of Tokyo, Sayo-cho, Sayo, Hyogo 679-5198, Japan. f Synchrotron SOLEIL-CNRS, L’Orme des Merisiers, Saint-Aubin, BP48, 91192 Gif-sur-Yvette cedex, France.
g Laboratoire de Chimie Physique Matière et Rayonnement, UPMC, CNRS, F-75231 Paris Cedex 05, France. h Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, United
Kingdom. Email: [email protected], [email protected]
Keywords: Iridates, Oxygen K edge RIXS, unconventional Mott insulators, magnetic excitations, Spin-Orbit exciton. Iridates are 5d TM oxides which have called much attention because of the observation of novel insulating [1] and correlated metallic ground states [2] as well as for the fascinating theoretical proposals envisioned (superconductivity and unusual topological phases) for them [3]. The key ingredients of iridates are: Ir 5d band behavior, strong Spin-Orbit coupling (SOC) and moderate electronic correlations [3] (See Figure 1). Iridates of the Srn+1IrnO3n+1 (n=1,2,∞) (Ruddlesden-Popper) series display a metal to insulator transition as the number (n) of IrO2 of layers is reduced [4]. Resonant Inelastic X-ray Scattering (RIXS) is an established technique which can provide invaluable information on the electronic and low energy sector of the Hamiltonian by probing elementary excitations in solids [5]. By measuring the O K-edge RIXS response (Figure 2) of the insulating members of the Ruddlesden-Popper series (n=1 and 2), we identified and registered the momentum dispersion of magnetic modes (Figures 3 and 4). The energy of the low energy modes correlates well with that of single magnons observed by Ir L3 RIXS (Figures 3 and 4) [6]. This suggests that the magnetic excitations observed in insulating iridates by O K-edge RIXS correspond not to bi-magnons (as in cuprates [7]) but to single magnons (Figures 3 and 4). This interpretation was recently confirmed by theoretical work done by Kim and van der Brink [8], thus our work is the first experimental verification of a novel selection rule for magnetic excitations during indirect RIXS processes for systems with strong SOC. Additionally, an excitation with marked Ir5d character was also identified in all the O K-edge RIXS spectra of the studied iridates, including correlated metallic Bi2Ir2O7 [2]. While the spectral shape of this excitation seems to be related to the strength of electronic correlations in the system, its energy again seems to correlate well with that of the so called Spin-Orbit exciton also observed by Ir L3 RIXS on insulating iridates (Figures 3 and 4) [6]. [1] M. K. Crawford et al., PRB 49, 9198 (1994). [2] G. Cao et al., PRB 76, 100402(R) ( 2007) and T. F. Qi et al., J. Phys.: Cond. Matt. 24, 345601 (2012). [3] W. Witczak et al., arXiv:1305.2193v1 (2013). [4] S. J. Moon et al., PRL. 101, 226402 (2008). [5] L. J. P Ament et al., Rev. Mod . Phys. 83, 705 (2011). [6] J. Kim et al., PRL. 108, 177003 (2012) and J. Kim et al., Nature Comm. 5, 4453 (2014). [7] V. Bisogni et al., PRB 85, 214527 (2012). [8] B. H. Kim and Jeroen van den Brink, arXiv:1404.2040v1 (2014).
UNPA MESYRUM 2014
42
Figure 1. Key ingredients in iridates: extended 5d radial distribution (upper panel) and Spin-Orbit parameter (lower panel).
Figure 2. Comparison between Ir L3 RIXS and O K edge RIXS processes.
Figure 3. Low energy excitations in Sr2IrO4 along Pi0 direction (left panel) observed by O K edge RIXS and for Ir L3 RIXS along different symmetry directions (right panel).
Figure 4. O K-edge RIXS temperature dependent studies on Sr3Ir2O7 at delta-45 in Pi0 and PiPi directions (left panel) and Ir L3 RIXS on Sr3Ir2O7 (right panel).
UNPA MESYRUM 2014
43
Synchrotron single-crystal crystallography as a novel resource in crustacean biology and aquatic health
Rogerio R. Sotelo-Mundo a, *, Alonso López-Zavalaa, Enrique Rudiño-Piñerab, Luis G. Briebac, Vivian Stojanoff
c
aCentro de Investigación en Alimentación y Desarrollo, A.C. (CIAD), Hermosillo,83304, México bInstituto de Biotecnología (IBT-UNAM), Cuernavaca, 62250, México
c Laboratorio Nacional de Genómica para la Biodiversidad (LANGEBIO), CINVESTAV Unidad Irapuato. Irapuato, Guanajuato, 36500 México
cNational Synchrotron Light Source (NSLS), Brookhaven National Laboratory (BNL), Upton,NY11973, USA
E-mail: [email protected]
Keywords: shrimp, prawn, protein crystallography, single-crystal Structural biology is a key component of any rational drug design and knowledge of emergent disease. In particular, the study of non-model organisms, such as marine crustaceans is relegated since they are considered to be orthologous to models like Drosophila, C. elegans or sometimes zebrafish. Nonetheless, shrimp aquaculture is an important economic activity worldwide that has been affected by several epizooties of viral and bacterial nature. A few years ago, structural knowledge of white Pacific shrimp (Litopenaeus vannamei) proteins was non-existent. CIAD along with IBT-UNAM and LANGEBIO-CINVESTAV started a structural initiative to determine the crystal structures of white shrimp proteins. CIAD had extensive experience in producing recombinant proteins and joined IBT-UNAM to collect data at NSLS-BNL, aside of training and extensive collaboration. The project involved extensive logistics to travel from Hermosillo, México to Long Island, NY with liquid-nitrogen cooled crystals to diffract, and to implement open-source software platforms to solve the structures. LANGEBIO-CINVESTAV provided knowledge and experience dealing with DNA-binding proteins and its biochemical characterization. To date, there are 11 released and 4 unreleased structures from L. vannamei single-crystal X-ray diffraction in the Protein Data Bank database (www.rcsb.org). This shows that synchrotron radiation has been made possible to start a modest structural biology program for non-model organisms with global importance. This work is hampered for lack of traveling money and restriction in Mexican grants. The perspectives of our group are into structural studies of proteins from the viral pathogen white spot syndrome virus and specific strains of Vibrio parahaemolyticus.Availability of a national synchrotron in México would make available structural studies not only for human disease applications, but also for veterinary and agronomic molecular studies. Support is acknowledged from grants from INAPESCA and CONACYT (México).
UNPA MESYRUM 2014
44
XANES and EXAFS Structural Characterization of Catalysts
Sergio A. Gómez Torres
Universidad Autónoma Metropolitana – Iztapalapa Departamento Ingeniería de Procesos e Hidráulica, División CBI, 09340. México DF.
Email: [email protected]
Keywords: XANES, EXAFS, Heterogeneous Catalysts. Abstract. Today, catalysis plays a prominent role in our society. As a fact, more than 90% of all chemicals and fuels produced within the chemical industry have been in contact with one or more catalysts. Also, catalysis has become indispensable in environmental pollution control. All those processes involve catalytic reactions in which more than one turnover or event occurrs per catalytically active site. Catalysts may be metals, oxides, zeolites, sulfides, carbides, organometallic complexes, and enzymes. In practice heterogeneous catalysis is primarily a technology that draws on many fields such as organic chemistry, surface chemistry, chemical kinetics, thermodynamics, solid-state physics, among others. Even when the principal industrial properties of a catalyst are its activity, its selectivity, and its stability, from a fundamental point of view, the ultimate goal of catalyst characterization should be to examine the surface atom by atom, and under the same conditions that those used during catalytic reaction tests [1]. Characterization of catalysts at the microscopic level concerns with the details of adsorption on surfaces, reaction mechanisms, theoretical modeling, and surface science. The main goal is related to both the fundamental knowledge and to design of high performance industrial catalysts. Then, the aim of this work is to present the impact of both XANES and EXAFS in the structural characterization of catalysts. Here, several examples are presented in order to explain the main relevance of X-ray absorption characterization in the catalysts field. X-ray absorption near edge spectroscopy (XANES) focuses on the shape of the absorption edge. It is highly sensitive for the valence state of the atom and its bonding geometry. Then, XANES might easily be the most popular characterization technique for determining catalyst composition. As an example, results of iron oxide-supported gold samples characterized by XANES spectroscopy during treatments in flowing H2 at increasing temperature show that reduction of Fe3+
to Fe2+ on the support occurs at lower temperatures in samples containing gold than on samples of the bare support [2]. These results emphasize the power of XANES spectroscopy in following changes in the oxidation states of both gold and iron and suggest that the role that gold might have in promoting the reduction and crystallization of iron oxide support is to provide sites for H2 dissociation (Figure 1). Hydrogen moieties might spillover from the gold nanoparticles to the support, promoting its reduction and ensuing structural changes. A second example is related to the deactivation of Au/CeO2 catalysts during the selective oxidation of CO in H2 rich atmospheres, which allows high purity H2 streams. By combining XANES and in-situ DR UV-vis results it was confirmed that the reduction (Figure 2) and sintering of the Au species, as well as, the reduction of CeO2 tracks the deactivation during long-term reaction experiments [3]. On the other hand, Extended X-ray absorption fine structure (EXAFS) deals with the interference effects visible in the absorption spectrum beyond the edge, and provides detailed information on the distance, number, and type of neighbors of the absorbing atom. EXAFS was introduced into catalysis, around 1975 and it was considered to be one of the most promising techniques for the characterization of catalysts [1]. Unfortunately, these expectations have not quite been fulfilled, because the analysis of the EXAFS data is highly complicated. However, several successful applications have proven that EXAFS can be a very powerful tool in catalysis [4-6]. To illustrate the information that EXAFS provides we use a study reported by Sinfelt et al. [7] on bimetallic Ru-Cu/SiO2. Quantitative analysis of the EXAFS data revealed that the first coordination shell of the average Ru atom in the bimetallic catalyst contains 90% Ru and 10% Cu, whereas the first coordination shell of the average Cu atom contains 50% Cu and 50% Ru. This, together with the
UNPA MESYRUM 2014
45
overall lower coordination of copper, is in agreement with particles consisting of a Ru core and an outer shell of Cu atoms. EXAFS results also reveals that exposing the bimetallic catalyst to oxygen at room temperature, the oxygen oxidizes only the copper and leaves ruthenium largely unaffected. These results again confirm that copper is present in a shell surrounding a core consisting mainly of ruthenium. Finally, X-ray absorption spectroscopy could give accurate determination of the catalytic structures, even in the working state, leading to Structure − Activity correlations that underlie heterogeneous catalyst design.
11850 11900 11950 12000 12050
Nor
mal
ized
abs
orba
nce,
u. a
.
Energy, eV
(a)
(b)
(c)
(d)
(e)
(f)
Figure 1. Dependence of the position of the Fe K edge with respect to the treatment temperature in flowing H2 for the bare support (�) and the supported gold samples. 2% Au (¢) and 6% Au (r) [2].
Figure 2. XANES of Au/CeO2 catalysts: fresh (a), 0.24 Au wt %, (b) 0.74 Au wt %, (c) 1.5 Au wt-% and after 160 h in PROX to 80 °C (d) 0.24 Au wt-%, (e) 0.74 Au wt-% and (f) 1.5 Au wt-% [3].
References: [1] J. W. Niemantsverdriet. Spectroscopy in Catalysis. An Introduction. 3rd Edition (2007), WILEY-VCH, Verlag GmbH & Co. KGaA, Weinheim. [2] S. A. Jimenez-Lam, M. G. Cardenas-Galindo, B. E. Handy, S. A. Gómez, G. A. Fuentes, and J. C. Fierro-Gonzalez. J. Phys. Chem. C 115 (2011) 23519. [3] J. A. Hernández, S. A. Gómez, T. A. Zepeda, J. C. Fierro-González, and G. A. Fuentes. Submited to Applied Catalysis A (Nov. 2014). [4] J. F. Goellner, B. C. Gates, G. N. Vayssilov, N. Rösch. J. Am. Chem. Soc. 122 (2000), 8056. [5] J. C. Fierro-Gonzalez, S. Kuba, Y. Hao, and B. C. Gates. J. Phys. Chem. B 110 (2006) 13326. [6] Y. Iwasawa, X-ray Absorption Fine Structure(XAFS) for Catalysts and Surfaces. World Scientific, Singapore, 1996. [7] J.H. Sinfelt, G.H. Via, and F.W. Lytle, J. Chem. Phys. 72 (1980) 4832.
UNPA MESYRUM 2014
46
Polymer fibers and cementitious matrix interaction: a multiscale characterization
Daniel Hernández-Cruz1, Craig W. Hargis2, Sungchul Bae2, Pierre A. Itty2, Cagla Meral2, Jolee Dominowski3, Michael J. Radle3, Wilson L. Nguyen2,David A. Kilcoyne4, Dula Parkinson4, Paulo J.M. Monteiro2, Claudia P.
Ostertag2.
1 Facultad de ingeniería, UNACH, Tuxtla Gutiérrez, Chiapas 29050, México 2 Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720, USA
3 Dow Construction Chemicals, Midland, MI 48667, USA 4 Advanced Light Source, LBNL, Berkeley, CA 94720, USA
Email: [email protected] Keywords: STXM, µCT, reinforcing concrete fiber, NEXAFS This work has been focused on the interactions and potential bonding between polymeric fibers and cementitious materials were studied using scanning transmission X-ray microscopy (STXM) and microtomography (µCT), together with a series of mechanical test. STXM and µCT have showed great potential to characterize the polymer fiber-hydrated cement-paste matrix interface, as well as differentiating the chemistry of the two components of a bi-polymer (hybrid) fiber – the polypropylene core and the ethylene acrylic acid copolymer sheath. Chemical interactions between the hybrid fiber and the cement hydration products were observed, which indicated the chemical bonding between the sheath and the hardened cement paste matrix, as can be seen in Figure 1a. Results obtained from µCT, allowed visualization of the performance of the samples, and the distribution and orientation of the two types of fiber in mortar, shown in Figure 2a-b. Beam flexure tests confirmed improved tensile strength of mixes containing hybrid fibers, and expansion bar tests showed similar reductions in expansion for the polypropylene and hybrid fiber mortar bars. In addition, Polymeric fiber reinforced cementitious composites were studied under loading scenarios (in-situ tensile test) in order to investigate the fiber-crack properties necessary to achieving strain hardening behavior and internal confinement effects, an example is shown in figure 2c.
Figure 1, (a) an OD image showing the area where a line scan at Ca L edge was performed; (b) a zoomed in image showing the line scan position and the four regions where the NEXAFS spectra were extracted; (c) a line scan image showing the four regions where the spectra was extracted; and (d) the four extracted NEXAFS spectra.
5 µm
2 µm
a) b)
d)
1 2 3 4
1
2
3
4
4
32
1
c)
340 350 360 370 380340 344 348 352 356 360
Intens
ity (a
.u.)
E nerg y (eV)
(1) core (2) s hea th01 (3) s hea th02 (4) epoxy
Energy (eV)
0
2
4Lenght
(µm)
6
8
10
UNPA MESYRUM 2014
47
Figure 2, 3D images showing fiber distribution in a cement mortar: (a) PP fiber block. Scale bar represents 2 mm, and b) a PP fiber cylinder under in-situ loading condition (tensile test). [1] [2] [3] D. Hernández-Cruz, C.W. Hargis, S. Bae, P.A. Itty, C. Meral, J. Dominowski, M.J. Radler, D.A. Kilcoyne, P.J.M. Monteiro Cemement and Concrete Composites 48 (2014) 9-18. [4]
a)
b) b) a)
UNPA MESYRUM 2014
48
Applied synchrotron radiation in the study of hybrid materials
Marlene González a, A. Adela. Lemus-Santana a, Joelis. Rodríguez-Hernández b, Marcelo Knobel c, Edilso Regueraa
a Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, IPN, D.F, 11500,
México b Instituto de Investigaciones en Materiales, UNAM, D.F. 04510, México
c Instituto de Física ‘‘GlebWataghin’’,Universidade Estadual de Campinas ,Sao Paulo, 13083-970, Brazil Email: [email protected]
Keywords: Molecular magnets, imidazole derivatives, intermolecular interactions. Abstract The purpose of the present work is the intercalation of organic linkers (Imidazole derivatives, ImD) between inorganic layers (T[Ni(CN)4] to form hybrid inorganic/organic materials (T(ImD)2[Ni(CN)4]) as a strategy for combining an inorganic material, potentially able to reach high Tc with a system of hanging molecules with possibility of interactions between them. This study focuses in the development of new multifunctional materials with the combination of different properties within the same material. Most interesting are properties that can interact mutually to result in cooperative effects, [1] such as cooperative spin coupling of metal unpaired electrons through pillar chains. However, magnetic exchange generally requires short bridges between the spin carriers, which is not always compatible with the use of long diamagnetic connecting ligands or with single atom, coordinated organic ligands. In this case, we prepared the new materials T(ImD)2[Ni(CN)4] where T = Mn, Co and Ni, while ImD = 2-methylimidazole (MeIm), 2-ethylimidazole (EtIm) and benzimidazole (BzIm) as powder samples. For the parental inorganic layers a wide polymorphism has been determined [2]. The polymorphic nature emphasizes the importance of the weak, but finite non-covalent intermolecular interactions playing a key role in determining the ground state magnetic behavior. The existence of polymorphic materials should be expected, in studies of molecule-based magnets and like polymorphs frequently exhibit different magnetic behaviors, it is crucial to know the structure of the material being studied, and this is best determined at the magnetic ordering temperature [3]. Although it is possible to solve structures using laboratory powder data, for organic molecules with light atoms, powder patterns have usually few broad peaks, in which overlap a frequent feature. In these cases, the use of synchrotron powder data makes the process of solving the crystal structure much easier [4]. Thus, the success of traditional techniques for structure solution is generally enhanced by using data recorded on an instrument with the highest possible resolution. However, for direct-space structure solution techniques that employ a figure-of-merit based on a profile R-factor (such as Rwp), the most important requirement is not high resolution itself, but rather that the peak profiles are well-defined and accurately described by the peak shape and peak width functions used in the structure solution calculation [5]. Synchrotron radiation has provided the optimum conditions for obtaining individual peak intensities with the minimum background level. This is primarily due to the high brightness and good vertical collimation of synchrotron radiation [6]. This study sheds light on the intermolecular interactions between imidazole derivative molecules (MeIm, EtIm and BzIm) intercalated in T[Ni(CN)4] layers to form a solid of formula unit T(ImD)2[Ni(CN)4]. Crystal structure of these hybrid inorganic–organic solids were solved and refined from X-ray powder diffraction data. The involved imidazole derivative molecules were found coordinated through the pyridinic N atom to the axial positions for the metal T in the T[Ni(CN)4] layer. In the interlayer region ligand molecules from neighboring layers remain stacked in a face-to-face configuration through dipole–dipole and quadru- pole–quadrupole interactions. These intermolecular interactions show a pronounced dependence on the substituent
UNPA MESYRUM 2014
49
group and are responsible for an ImD-pillaring concatenation of adjacent layers. This is supported by the structural information and the recorded magnetic data in the 2–300 K temperature range. The samples containing Co and Ni are characterized by presence of spin–orbit coupling and pronounced temperature dependence for the effective magnetic moment except for 2-ethyl-imidazole related to the local distortion for the metal coordination environment. For this last one ligand, a weak ferromagnetic ordering ascribed to a super-exchange interaction between T metals from neighboring layers through the ligands π–π interaction was detected.
Figure 1. Temperature dependence for the effective magnetic moment in Co(ImD)2[Ni(CN)4]. Inset: hysteresis loop in the magnetization curve for Co(EtIm)2[Ni(CN)4].
Figure 2. Unit cell of T(BzIm)2[Ni(CN)4] hybrid materials. For clarity just some interacting ligands are shown.
References [1] P. Dechambenoit and Jeffrey R. Long Chemical Society Review, 40 (2011) 3249–3265 [2] J. Rodríguez-Hernández, A.A. Lemus-Santana, C.N. Vargas, E. Reguera Comptes Rendus Chimie 15 (2012) 350–355. [3] J. S. Miller. Chemical Society Review, 40 (2011), 3266–3296. [4] J. A. Kaduk. JCPDS-International Centre for Diffraction Data 2000, Advances in X-ray Analysis, 42 (2000) 333-354 [5] Kari Rissanen (Volume Editor). Advanced X-Ray Crystallography Vol. 315. Springer-Verlag Berlin Heidelberg 2012. [6] L.A. Smitha, R.B. Hammond, K.J. Robertsb, D. Machinc, G. McLeod Journal of Molecular Structure 554 (2000) 173-182.
UNPA MESYRUM 2014
50
Characterization and evaluation of the adsorption of Pb (II) by Typha latifolia roots
Candy Carranza-Alvarez1, Luis Rodrigo Ramiro Bautista1, Alejandro Hernández-Morales1, Juan José Maldonado-Miranda1, Nahúm Medellín-Castillo2
Unidad Académica Multidisciplinaria Zona Huasteca de la Universidad Autónoma de San Luis Potosí1, Calle Romualdo del Campo No. 501, Fraccionamiento Rafael Curiel, Ciudad Valles, San Luis Potosí, C.P. 79060,
México
Facultad de Ingeniería de la Universidad Autónoma de San Luis Potosí, Dr. Manuel Nava # 8, Zona Universitaria poniente, San Luis Potosí, S.L.P., C.P. 78290, México2.
Email: [email protected]
Keywords: Typha latifolia, adsorption, lead Abstract Text The use of adsorbents in various environmental applications has increased significantly in recent years. The current adsorbents have very low adsorption capacities for no ionizable organic compounds and especially anions, and therefore, these adsorbents are not used efficiently in the removal of such compounds in aqueous solution. It is therefore necessary to develop new adsorbents to remove most compounds in aqueous solution (1). An alternative is the use of plants as Typha latifolia. Previous studies have shown that T. latifolia has the ability to accumulate up to 37 mg/kg of Pb [2] and remove 7.5 ppm Pb in ten days [3]. Therefore, the aim of this study was to determine the ability of the roots of T. latifolia in the adsorption of lead (II) from water, to propose it as a viable, low-cost biosorbent. To do this, characterize the result of Typha latifola by scanning electron microscopy were carried out and determining active sites by the method of acid-base titration proposed by Boehm (2002) to evaluate the adsorption capacity. Analysis by scanning electron microscopy revealed that the surface of the root of T. latifolia, unsaturated and saturated, is constituted by elongated and slightly porous particles, composed of cellulose and lignin together (Figure 1). The concentration of acidic and basic sites T. latifolia root was 0.37 and 0.12 meq / g, respectively, so it is considered that the root has already slightly acid character which has a higher concentration of acid sites (Table 1). The study of the effect of pH and temperature on the adsorption isotherm of Pb (II) on the root of T. latifolia found that this biosorbent ability to remove lead is greatly dependent on pH and temperature of the solution, increasing by increasing the pH and greater amount of adsorbed temperatura. The amount of mass of Pb (II) with the biosorbent was 21.85 mg / g at pH = 5 (Figure 2). Synchrotron radiation techniques such as spectroscopy and X-ray spectrum-infrared microscopy have been used in the characterization of biosorbents materials and processes for biosorption of Cr Typha latifolia plants [4]. In the study of the interaction of elements with biosorbents materials has also been used the technique of extended X-ray Absorption Fine Structure (EXAFS) to determinart coordination number and structure of the complexes of Cr at the surface of the biosorbents materials like a sargassum macroalgae [5], these techniques for characterizing the adsorption processes. Spectroscopy techniques of X-ray absorption near edge (XANES) have also been employed in the determination of the oxidation state and speciation As compounds adsorbed on biomass obtained from animal proteins [6]. [1] R. Leyva-Ramos. Capítulo 3. Fundamentos de adsorción en sistemas líquido-sólido. In Tecnologías
económicas para el abatimiento de arsénico en aguas, (Eds): Marta I. Litter, Ana María Sancha, Ana María Ingallinella, CYTED, 2011, 43-55 pp.
[2] C. Carranza-Álvarez, A.J. Alonso-Castro, M.C. Alfaro de la Torre, R.F. García de la Cruz. Accumulation
and distribution of heavy metals in Scirpus americanus and Typha latifolia from an artificial lagoon in San Luis Potosí, México, Water Air and Soil Pollution. 188: 2008, 297-309 pp.
UNPA MESYRUM 2014
51
[3] A.J. Alonso-Castro, C. Carranza-Álvarez, M.C. Alfaro De la Torre, L. Chávez-Guerrero, R.F. García De la
Cruz. Removal and accumulation of cadmium and lead by Typha latifolia exposed to single and mixed metal solutions. Arch Environ Contam Toxicol, 57 (2009), 688-696 pp.
[4] C. Ya-Li, H. Xia-Qing, L. Hong-Wei, Q. Ting-Ting, L. Ru-Zhong, J. Hong, Y. Han-Qing. Biosoprtion of Cr by typha angustifolia: mechanism and responses to heavy metal stress: Bioresour Technol, 17, 160 (2014), 89-92 pp.
[5] Y.M. Zheng, T. Liu, J. Jiang, L. Yang, Y. Fan, A.T.S. Wee, Y.P. Chen. Characterización of hexavalent chromium interaction with sargassum by Xray absoption fine structure spectroscopy, and quantum chemistry calculation. Journal of colloid and interface science 2, 356 (2011), 741-748 pp.
[6] M.C. Teixeira, V.S.T. Ciminelli. Development of a bisorbente for arsenite: Structural modeling based on X ray spectroscopy. Environ. Sci. Technol., 39, 895-900 pp.
[1] J. L. Gardea-Torresdey, J. R. Peralta-Videa, G. de la Rosa, J.G. Parsons. Coordination Chemistry Reviews
249 (2005) 1797-1810. [2] B. J. Alloway (Ed.), Heavy Metals in Soils, second ed., Blackie Academic & Professional, London, 1995. [3] S. Dushenkov, Y. Kapulnik, in: I. Raskin, BD. Ensley (Eds.), Phytoremediation of Toxic Metals: Using
Plants to Clean Up the Environment, John Wiley and Sons Inc., New York, 2000, p. 89. [4] E. A. Gomez, The nanoparticle formation and uptake of precious metals by alfalfa plants, MS thesis,
Department of Chemistry, University of Texas at El Paso, El Paso, TX, July 2002, 81 pp.
Figure 1. Photomicrograph of T. latifolia root. A) unsaturated lead to 36 ×; B) saturated with lead
A B
UNPA MESYRUM 2014
52
Figura 2. Adsorption of Pb (II). Adsorption in aqueous solution on the root of Typha latifolia to different pH values and T = 25 ° C. The lines
represent the Freundlich isotherm
Table 1. Datos experimentales para calcular la concentración final y la concentración de sitios activos
Sites m (g)
CT (eq/L)
VT (L)
Vm (L)
Cin (eq/L)
Vin (L)
Cfn (eq/L)
Csa (meq/g)
Acid 0.5003 0.010 0.025 0.040 0.010 0.050 0.00625 0.37 Basic 0.5007 0.010 0.035 0.040 0.010 0.050 0.00875 0.12
UNPA MESYRUM 2014
53
Use of synchrotron infrared microspectroscopy for molecular identification of useful products obtained from lignocelulosic materials pretreated with steam explosion.
Carlos Molinaa, Arturo Sánchezb, Idania Valdez-Vazquezc, Delfino Franciad, Guadalupe de la Rosa Álvareza*.
a Depto. de Ingeniería Química, Electrónica y Biomédica, Universidad de Guanajuato., León Gto., 37150,
México b CINVESTAV - IPN. Unidad de Ingeniería Avanzada, Guadalajara Jal., 45019, México
c Unidad Académica Juriquilla, Instituto de Ingeniería. UNAM., Queretaro Qro., 76230, México dDepto. de Ciencias Ambiéntales , DICIVA, Universidad de Guanajuato, Irapuato Gto., 36500, México.
Email: [email protected] Keywords: Lignocellulosic, Steam explosion, Wheat Straw, Biofuels Lignocellulosic biofuels can be produced from materials such as agro-wastes (i.e., wheat straw), forage residues (i.e., softwood), etc., under a biochemical platform which comprises four fundamental steps: (i) pretreatment, (ii) hydrolysis, (iii) fermentation and (iv) downstream processes1. In this context, pretreatment process is performed in order to separate the three principal components of lignocelulosic materials: cellulose, hemicellulose and lignin. One of these pretreatments is steam explosion which consist in exposing lignocellulose to high temperatures and pressures. In this process it is possible to obtain a certain degree of delignification. The structure of lignin can be transformed to useful products depending on the temperatures and pressures used in this pretreatment. Lignin is now considered as the main aromatic renewable resource. It represents an excellent alternative feedstock for the elaboration of chemicals and polymers. Lignin is a highly abundant biopolymeric material that constitutes, in addition to cellulose, one of the major components in structural cell walls of higher vascular plants. Large quantities of lignin are yearly available from numerous pulping processes such as paper and biorefinery industries. Lignin extraction from lignocellulosic biomass (wood, annual plant) represents the key point to its large use for industrial applications. One of the major problems still remains is its unclearly defined structure and its versatility according to the origin, separation and fragmentation processes, which mainly limits its utilization. While currently often used as a filler or additive, lignin is rarely exploited as a raw material for chemical production. However, it may be an excellent candidate for chemical modifications and reactions due to its highly functional character (i.e., rich in phenolic and aliphatic hydroxyl groups) for the development of new biobased materials2. This work proposes the use of synchrotron radiation, particularly IR, with the objective of identifying the different useful products that can be obtained from the lignin decomposition under several operative condition (temperature and pressure), with steam explosion pretreatment of WS in range the of 60 lb/in2 to 600 lb/in2. [1] Sánchez A. Sevilla-Güitrón V., Magaña G., Gutierrez L. (2013). Parametric analysis of total costs and energy efficiency of 2G enzymatic ethanol production. Fuel; 113: 165–179. [2] Laurichesse S., Avérous L. (2014). Chemical modification of lignins: Towards biobased polymers. Progress in Polymer Science, 39; 1266–1290.
UNPA MESYRUM 2014
54
Structural study of solid solutions W1-xMoxO3-0.33H2O and Bi2W1-xMoxO6
Arzola-Rubio A a, Basurto-Cereceda S a, Camarillo-Cisneros J a, Fuentes-Cobas L a, Ornelas C a and Paraguay- Delgado F a.
a Física de Materiales, Centro de Investigación en Materiales Avanzados S C., Chihuahua, 31109, México.
Email: [email protected]
Keywords: semiconductors, electron microscopy (STEM, TEM and SEM), crystallography. Mo Solid solutions Tungstates are of great interest for solar harvesting. Thanks for their polymorphism, these materials show physical/chemical properties to be used in photocatalysis [1-3], hydrogen production [4-5] and charge batteries [6-8]. These oxides with two or three metals, such as binary tungsten-molybdenum oxides (W1-
xMoxO3) or trimetallic with Bi (Bi2W1-xMoxO6), show enhanced properties in comparison with unary Tungsten and Molybdenum oxides (WO3, MoO3). The materials’ band gap (W1-xMoxO3 and Bi2W1-xMoxO6) tends to decrease by varying the percentage of Mo/W [9-10]. These values will allow us to take advantage of the visible solar radiation for different important purposes. These materials were synthetized by hydrothermal method from metallic salts with different Mo percentages (x = 0.25, 0.50, 0.75 and 1). The characterization by crystallographic methods shows a great problem to be indexed categorically, due to the interplanary proximity distances; that is why we use synchrotron generated radiation because of its great intensity and monochromaticity. In this present work we show studies of the characterization of these materials such as conventional XRD, SAED, Synchrotron radiation and Rietveld simulations. In Figure 1 we show the XRD patterns comparison of conventional XRD and synchrotron. In this graphic was compared 1/q vs. intensity using Fullprof sowtare. We noticed a subtle difference, confirming the orthorhombic phase, without changes in the crystal lattice. In the synchrotron patterns, we can see the alumina sample holder peaks at 2θ= 40 and 50°. Figure 2a shows the compound W0.25Mo0.75O3 where we can see the morphology of long crystals around 337±223 nm and figure 2-b shows the SAED the monocrystality of the sample. We have fully characterized the whole samples having just pending a categorical detailed study of the solid solutions. Acknowledgment: Thanks to the Electra Synchrotron at Trieste Italy for the XRD studies References [1] H. Kim, J. Kim, W. Kim, W. Choi. J. Phys. Chem. C, 2011, 115 (19), pp 9797–9805. [2] F. Wang, C. D. Valentin, G. Pacchioni. J. Phys. Chem. C, 2012, 116 (16), pp 8901–8909. [3] M. Lu, C. Shao, K. Wang, N. Lu, X. Zhang, P. Zhang, M. Zhang, X. Li, Y. Liu. ACS Appl. Mater.
Interfaces, 2014, 6 (12), pp 9004–9012. [4] H. Katsumata, Y. Tachi, T. Suzukib, S. Kanecoa. RSC Adv., 2014, 4, 21405–21409. [5] Z. Pap, E. Karacsonyi, L. Baia, L. C. Pop, V. Danciu, K. Hernadi, K. Mogyorosi, A. Dombi. Phys. Status
Solidi B 249, 2012, No. 12, 2592–2595. [6] X. Xue, B. He, S. Yuan, L. Xing, Z. Chen, C. Ma. Nanotechnology 22 (2011) 395702 (6pp). [7] R. H. Coridan, K. A. Arpin, B. S. Brunschwig, P. V. Braun, and N. S. Lewis. Nano Lett., 2014, 14 (5), pp 2310–2317. [8] Y. Djaoued, S. Balaji, N. Beaudoin. Journal of Sol-Gel Science and Technology December 2013, Volume 68, Issue 3, pp 516-525. [9] Taurino, A.; Catalano, M.; Rella, R.; Siciliano, P.; Wlodarski, W. J. Appl. Phys. 2003, 93, 3816–3822. [10] May, R. A.; Kondrachova, L.; Hahn, B. P.; Stevenson, K. J. J. Phys. Chem. C 2007, 111, 18251–18257.
UNPA MESYRUM 2014
55
Figure 1. X-ray diffraction comparison by synchrotron and conventional for samples WO30.33H2O, W1-.25Mo0.25O30.33H2O and W1-0.75Mo0.75O30.33H2O.
Figure 2a TEM bright field and Fig 2b SAED for the sample W1-0.25Mo0.25O30.33H2O.
UNPA MESYRUM 2014
56
Theory and Experiment for the Single Photoionization of P+.
E. M. Hernándeza,h, Sultana Naharb, A. Aguilard, Olmo Gonzáleze, D. Macalusog, A. Antillóna, A. Morales-Moria, A. M. Juáreza, D. Hanstorpf, Aaron Covingtonc, Kiattichart Chatkunchc and G. Hinojosaa†
aInstituto de Ciencias Físicas, Universidad Nacional Autónoma de México, AP 48-3, Cuernavaca 62250,
Morelos, México. bThe Ohio State University.
cPhysics Department, University of Nevada, Reno, USA. dThe Advanced Light Source, Livermool Lawrence National Laboratory, Berkeley, CA, EEUU.
eKVI Atomic and Molecular Physics, University of Groningen, Zernikelaan 25, 9747AA Groningen, The Netherlands.
fDepartment of Physics, University of Gothenburg, SE-412 96 Gothenburg, Sweden. gDepartment of Physics & Astronomy, the University of Montana, Missoula, MT 59812, USA.
hFacultad de Ciencias, Universidad Autónoma del Estado de Morelos, México.
Email: [email protected]
Keywords: VUV spectroscopy, absorption lines, opacity, photoionization Abstract: The single photoionization cross section of P+ as a function of the photon energy was measured in the photon energy range of 18 to 50 eV at a constant photon energy resolution of 20 meV. A theoretical calculation based on relativistic Breit Puali method was developed. Both, the experimental and the theoretical spectrum consist of broad and sharp resonances superimposed on a large direct photionization cross section. The threshold region is specially interesting. The experiment was conducted at Lawrence Berkeley National Laboratory (LBNL). A comparison of the experimental and theoretical results will be presented in the poster session.- Open shell atoms of intermediate size are of fundamental interest because the electron correlation and the coupling of intermediate channels are known to be strong. An additional motivation are previous results of the photoinization of atomic phosphorus that showed interesting ionic thresholds where there is series overlapping and strong interaction with the continuum. In astrophysics, the photoionization (PI) cross sections and spectroscopy provides information about its abundance and are a fundamental tool in the non -local thermodynamic equilibrium models for intergalactic plasmas. Its detection is evidence of the process of nucleo-synthesis in stars. In addition, phosphorus abundances in the Universe are correlated to the possibility of life. Recent confirmation by the FUSE explorer (Far Ultraviolet Spectroscopic) of the presence of phosphorus and its ions in interstellar space plasmas has triggered a renewed interest in the study of the photoionization of phosphorus. The experiment was performed using the Ion Photon Beam end station on undulator beamline 10.0.1. of the Advanced Light Source (ALS) at LBNL. The method is based on the merged-beams technique [Phaneuf, 1999] and has been described in detail in previous measurements of photoionization cross sections for Cl+ [Hernández, 2014]. This technique's fundamental idea is to merge the two beams (photon-beam and the ion-beam) traveling in opposite directions over a common collinear path. As a result of their interaction, ions from the ion-beam may ionize again. Resulting and parent ions are separated and counted while all relevant parameters of both beams, and their overlap are measured. UVU radiation was generated with a 10 cm period undulator positioned in the 0.5 A constant current, 1.9 GeV synchrotron ring. This produced a highly collimated photon beam and negligible spacial divergence. The photon beam was filtered using a grazing-incidence spherical-grating monochromator. The photon energy was scanned by rotating the grating and translating the exit slit of the monochromator while simultaneously adjusting the undulator gap to maximize the photon-beam intensity. Results for the single photionization of P+ are presented in Figure 2.
UNPA MESYRUM 2014
57
The theoretical method is based on the relativistic Breit -Pauli described in detail elsewhere [Nahar, 2014]. The comparison with the experiment is consistent with the shape of the threshold. Several other resonances, apparently are obscured when the experimental resolution is applied to the data. Some of the resonances can be assign with the help of the calculation. However, the main resonant peaks remain to be clearly understood. The results for the present theoretical calculation are presented in Figure 1.
Figure 1. The single photoinization of P+ as a function of the photon energy
according to the theoretical method. Each pannel represents an initial state of P+.
Figure 2. Measurements of the single photoionization cross section of P+ as a function of the photon
energy. The spectrum was measured with a photon energy resolution of 20 meV. This spectrum will be compared with the theoretical calculation of figure 1.
Domke, M., Schulz, K., Remmers, G., Kaindl, G., and Wintgen, D., Phys. Rev. A, 53, 1424, (1996). King G. C., Tronc M., Read F. H., and Bradford R. C., Jour. Phys. B., 10, 2479, (1977). Hernández E. M., A. M. Juárez, A. L. D. Kilcoyne, et al., JQSRT, 151, 217 (2015). Phaneuf R. A., Havener C. C., Dunn G. H. and Muller A., Reports on Progress in Physics, 62, 1143, (1999). Sultana N. Nahar, Atomic Data Nuclear Data Tables 100, 1322-1336, (2014).
UNPA MESYRUM 2014
58
The use of Synchrotron Radiation in Surface Science
Leonardo Morales de la Garza
Universidad Nacional Autónoma de México Centro de Nanociencias y Nanotecnología
Apartado Postal No. 14, Ensenada, Baja California, 22800, México.
Keywords: Surface Science Techniques, Syncrotron Radiation Syncrotron Radiation was first detected last century around 1947, and by that time it was considered an annoying side effect of accelerators developed for high energy physics experiments. It was until the 1960´s that this light was used in the first generation syncrotrons, and it was in the 60´s when Ultra High Vacuum (UHV) techniques were developed giving the possibility of studing solid surfaces under control environment.
It is in the mid 1970´s that the use of syncrotron radiation was widley appreciated and some faccilities were dedicated only to the synchrotron light like the National Synchrotron Light Source (NSLS) at Brookhaven, New York USA. In NSLS most synchrotron light is produced at bending magnets and it is called second generation sources, these second generation sources produced a brightness increase of two order of magnitude with respect the first generation sources. Scince then many other synchrotron accelerators were built in USA, Europe and in Asia. [1]
More improvement has been achieved introducing new elements alternating with the magnets, like a
wiggler and an unulator, which the technical details are not treat in this work. They are called the third generation light sources and they have a sustantial improvement in brithness of up to 5 orders of magnitude.
Many techniques for characterizaising solid surfaces and nanostructures, use light as the probe to send
to interact with the solid surface. X-Ray Photoelectron Spectroscopy (XPS), Ultraviolet Photoelectron Spectroscopy (UPS), X-Ray Diffraction (XRD), Infra Red Spectroscopy (IRS), Fourier Transform IR (FTIR) just to mention some. [2].
Concerning the determnation of the structure of surfaces or nanomaterials the technique of Extended X-
Ray Adsorption Fine Structure (EXAFS) and the Near Edge X-Ray Adsorption Fine Structure (NEXAFS) are only possible with synchrotron radiation, since no other light source is usful for that porpose. [3]. [1] http://www.cem.msu.edu/~cem924sg/GraceMutaaga.pdf [2] D.P. Woodruff, T.A. Delchar, Modern Techniques of Surface Science 2nd. Edition, Cambridge University
Press, 1994. [3] G.A. Somorjai, Y Li, Introduction to Surface Chemestry and Catalysis, 2nd Edition, John Wiley & Sons,
2010.
UNPA MESYRUM 2014
59
Arginine kinase crystal structure in complex with arginine shows pre-organized phosphagen binding site
Alonso A. Lopez-Zavalaa, Rogerio R. Sotelo-Mundo a, Enrique Rudiño-Piñerab,Vivian Stojanoff c.
aCentro de Investigación en Alimentación y Desarrollo, A.C. (CIAD), Hermosillo, CP 83304, México
bInstituto de Biotecnología (IBT-UNAM), Cuernavaca, CP 62250, México
. cNational Synchrotron Light Source, Brookhaven National Laboratory, Upton, CP 11973, USA
E-mail: [email protected]
Keywords: arginine kinase, crystallographic structure, binary complex, shrimp Arginine kinase (AK) is a key enzyme for energetic balance in invertebrates mediated by phosphagens [1]. AK catalyzes reversible reaction between ATP and arginine to synthetize phosphor-arginine (Figure 1). Although AK is a well-studied system that has been isolated from several sources as monomeric 40 kDa protein and in some cases as an homodimer of 80 kDa [2]. Also, the structural work in AK has focused on free-ligand and ternary complex [3], however the structural details on the AK-arginine binary complex interaction remain less studied. In this work we determined three crystal structures of the Pacific whiteleg shrimp (Litopenaeus vannamei) arginine kinase: the free-ligand form (apoLvAK), in binary complex with arginine (LvAK-Arg) and a ternary transition state analog complex (TSAC) using X-ray protein crystallography. Crystals were grown using the microbatch and hanging drop method and diffracted in X6A beam line at NSLS. Data sets were analyzed using XDS [4] and phases problem were solved by molecular replacement in PHASER[6]. We found that the arginine guanidinium group makes ionic contacts with Glu225, Cys271 and a network of ordered water molecules. On the zwitterionic side of the amino acid, the backbone amide nitrogens of Gly64 and Val65 coordinate the arginine carboxylate (Figure 2). Glu314, one of proposed acid-base catalytic residues, did not interact with arginine in the binary complex. This residue is located in the flexible loop 310-320 that covers the active site and only stabilizes in the LvAK-TSAC. This is the first crystal structure of a guanidine kinase in binary complex with the guanidine substrate and could give insights into the nature of the early steps of phosphagenbiosynthesis. REFERENCES: [1] Ellington WR. Annuals Review of Physiolology. 63 (2001) 289–325. [2] Guo SY, Guo Z, Guo Q, Chen BY, Wang XC. Protein Expression and Purifcation. 29 (2003) 230-234. [4]Kabsch W. Acta Crystallographica Section D. 66 (2010) 125–1 [3] Zhou G, Somasundaram T, Blanc E, Parthasarathy G, Ellington WR. Proceedings of the National Academy of Sciences. 95 (1998) 8449–8454. [5] Mccoy AJ, Grosse-Kunstleve RW, Storoni LC, Read RJ. Acta Crystallographica Section D. 61 (2005) 458–464
UNPA MESYRUM 2014
60
FIGURES:
Figure 1. The reversible reaction catalyzed by AK. In the forward reac- tion, AK synthetizes phosphagens for energy-cell storage. Under rapid cellular-energy requirements, AK hydrolyzes the phosphagen to supply the
ATP cellular necessities, backward direction.
Figure 2. rystallographic structures free-ligand and arginine-complex LvAK. The substrate arginine is well stabilized via hydrogen bonds throw the guanidine-binding loop (residues 64–66). Glu224 in aligned toward the
guanidine end of arginine substrate (cylinders). Hydrogen bonds are shown as a dotted line using LvAK-Arg structure as reference. Arginine electron density is displayed as a blue mesh.
UNPA MESYRUM 2014
61
Analysis of the sintering of powder systems by in situ synchrotron microtomography
L. Olmosa, D. Bouvardbc, Christophe L. Martinbc, M. Di Michield aCoordinación de la Investigación Científica, Universidad Michoacana de San Nicolás de Hidalgo, Fco. J.
Mujica S/N, Ed. C-2 C.U., 58060 Morelia, Michoacán, México. bUniv. Grenoble Alpes, SIMaP and LMGP, 38000 Grenoble, France.
cCNRS dESRF, BP 220, 38043 Grenoble, France
Email: [email protected]
Keywords: sintering, 3D images, X ray microtomography, composite, porosity. Abstract. Powder metallurgy is a technique largely used to produce metallic or ceramic parts from powders. The final step of this process is a thermal treatment called sintering. During this step, interparticle bonds are created by mass transfer and the properties and dimensions of the part are acquired. Many research works (analytical, experimental and computer modeling) have been dedicated to understanding sintering phenomena [1-2]. In spite of these efforts important issues are still open, in particular concerning collective particle behavior [3], which can hardly be investigated with classical observation methods as electron microscopy. The aim of this work is thus to analyze the microstructure changes of various copper-based powder systems during sintering from 3D images provided by in-situ synchrotron microtomography and comparing results with previous works that have treated we homogeneous particle packings [4-5]. For this purpose we prepared three different samples: copper powder poured into quartz capillary, presintered copper samples including large pores and finally copper and alumina powder mixtures. A copper powder with a large size distribution (0-63 microns) was used in every case. Experiments were carried out at ID15 beamline of ESRF at Grenoble, France. Powders were sintered up to 1060°C under reducing atmosphere in a furnace placed between the X-ray source and the detector. During each experiment, 3D images were taken at various times of the thermal cycle. We obtained images with a resolution of 1.5 microns and the time of acquisition of every image was about a minute, Figure 1. Analysis of the 3D images was performed by using Aphelion, ImageJ and Avizo softwares. We were able to follow the changes of different parameters that characterized the sintering process at particle scale (particle size distribution, interparticle neck size, centre to centre distance (Figure 2), pore size distribution, Figure 3, and coordination number, Figure 4d) and to correlate these changes between each other and with macroscopic parameters. These data have been compared to the prediction of various models, either classical analytical models or discrete element simulations performed at Grenoble-INP, Figure 4. Conclusion In situ X-ray microtomography analysis of sintering of different systems based on copper powders has been carried out. The images obtained for close packed particle confirmed the homogeneity of densification of such systems. As expected, introducing defects in the packing leads to heterogeneous sintering. Artificially introduced macropores change very slowly even when the dense zones of the material undergo strong shrinkage. Mixing the copper powder with 20% volume fraction of alumina particle results in a very slow densification with significant particle rearrangement. The wealth of information that this technique provides in 3D allows a better understanding of phenomena such as the evolution of multiple contact deformation or particle rearrangement. These phenomena play a significant role in sintering, and more particularly in heterogeneous powder systems as demonstrated here. These preliminary results should help in devising future experiments centered on the comparison between in-situ microtomographic observations and DEM simulations. Because microtomographic observations allow tracking individual particles, they offer a very powerful and critical tool for comparing with DEM simulations. In the light of the present results, we believe that further progress is needed in measuring contact size from microtomographic images.
UNPA MESYRUM 2014
62
References [1] Coble R.L., J. Am. Ceram. Soc. 41, (1958), p. 55. [2] C.L. Martin, L.C.R. Schneider, L. Olmos and D. Bouvrd, Scripta Mat. 55, (2006), p. 425 [3] G. Petzow and H.E. Exner, Z. Metallkd., 67, (1976), p.279. [4] D. Bernard, D. Gendron, J.M. Heintz, S. Bordére and J. Etourneau, Acta Mater. 53, (2004), p. 121. [5] A. Vagnon, J.P. Rivière, J.M. Missiaen, D. Bellet, M. Di Michiel , C. Josserond and D. Bouvard, Acta Mater. 56, (2008), p. 1084.
Figure 1. Virtual slices of samples in the initial state and after sintering, (a) and (b): regular sample; (c) and (d): porous sample; (e) and (f): composite sample.
Figure 2. Normalized interparticle indentation h as function of densification ratio for several values of equivalent radius R* for the three samples.
Figure 3. Pore size distribution at several times of the sintering cycle for regular (a), porous (b) and composite (c) samples.
Figure 4. Evolution of the average indentation normalized by the average particle radius for simulation and experimental data (a), average indentation of particle pairs for several values of R̂ , (b) and Normalized coordination number vs. normalized relative density, (c).
UNPA MESYRUM 2014
63
INDOOR/OUTDOOR CHARACTERIZATION OF ISOTOPIC RATIOS OF LEAD IN AN ATMOSPHERE-POLLUTED AREA OF CHIHUAHUA CITY,
MEXICO
Marcos Delgado Riosa, Jorge L. Gardea-Torresdey b, Jason Parsons c, Jose R. Peralta-Videa b, Gustavo Cruz-Jimenez d
Elias Ramirez Espinoza e
a Universidad Autónoma de Cd. Juárez, Juárez, 32310, México
b University of Texas at El Paso, El Paso, 79968, U.S.A. c University of Texas Pan Am, Edinburg, 78539, U.S.A.
d Universidad de Guanajuato, Guanajuato, 36000, México
e Centro de Investigacion en Materiales Avanzados, Chihuahua, 31109, México Email: [email protected]
Keywords: Indoor/outdoor, lead, characterization Introduction. Lead (Pb) is a toxic heavy metal present in the atmosphere and in the environment in several chemical and physical forms. One form that is relevant to the makeup of pollutants is their presence as different isotopes. Pb has many possible sources and toxic pathways, isotopic ratios are an excellent way to survey Pb sources in atmospheric samples [1]. Pb isotopic ratios change slowly with the time since their sources are from radioactive decay of 238U, 235U, and 232Th, which produce 206Pb, 207Pb, and 208Pb, respectively. Thus the abundance of lead isotopes are conservative and their combinations depends on the geochemical age and the amount of U and Th in the area [1]. Methodology. For the outdoor sampling, a high-volume procedure was used which is described as follows: The duration of sampling was 24 hours per sample, with an air suction rate of 1.1-1.7 m3 min-1 using Whatman glass fiber filters as the support medium. The airflow was measured through pressure changes in the media at three times per sampling period. The high-volume sampler was situated at least two meters above the ground level and with a surrounding space of twenty meters without obstacles (trees, buildings, and hills). The glass fiber filters were pre-conditioned for 24 hours inside a desiccator containing silica gel. They were then weighed to the nearest 0.00001 µg, handled using latex gloves. The high-volume sampler was programmed to operate continuously for 24 hours. The comparison between outdoor and indoor samples will be performed based on two filters from the indoor sampler located in the center of two randomly-selected households, consisting of a 14 day sampling period (the high-volume system does not have the work capacity for 14 days with the same filter). Results and conclusions. An aerosol collection and Pb isotopic analysis was done in more than 80 sites across the Northern Hemisphere between 1994 and 1999, reporting a 206Pb/207Pb ratio of 1.173-1.231 and 1.159-1.188 for Eastern and Western United States, respectively, ranges that matching with our own data for outdoor environments (1.178±0.015)[2]. Similar 207Pb/206Pb ratios 0.865 from industrial cities in the central part of Russia [1]. A 206Pb/207Pb mean of 1.179±0.105 for their aerosol samples was obtained in Mexico City, showing that the main source of Pb in the city was the continuous resuspension of dust [3]. The average 206Pb/207Pb ratio obtained in our study for outdoor environment (1.178±0.015) is very close to the isotopic lead ratios reported for Mexico City, supporting the theory of the resuspension as the main source of Pb in Chihuahua City. This value concur with the data reported from Renberg et al. (2002) [4], establishing that atmospheric Pb pollution derived from metal smelting processes has a 206Pb/207Pb ratio less than 1.2. The indoor mean 206Pb/207Pb value is slightly larger than the outdoor ratio (1.211±0.011). Gasoline is no longer an important source of atmospheric Pb since our isotopic ratios are different from the lead isotopic ratios for Mexican gasoline reported by Martinez et al., 2004 [3]. In Mexico two different types of gasoline have existed since 1990: Magna, which has Pb isotope ratio of 0.874±0.001 for 206Pb/207Pb, and Premium which has a
UNPA MESYRUM 2014
64
206Pb/207Pb ratio of 0.881± 0.073. The main sources of Pb in Chihuahua City like smelting activities and use of leaded gasoline, were discontinued a couple of decades ago. Today, central industrial activities, shifting away from primary industry to tertiary industry, have become the sources of Pb and other heavy metals are becoming non-existent. Thus, the resuspension of street dust is becoming the main source of Pb contamination. The results of this study were similar to the results of other studies which have shown that the most important sources of PM10 and Pb in the indoor environment was the transport and resuspension of external dust. In the case of Pb, the filters had only trace levels. Under the conditions of this study, no public health concern could be documented relating to inorganic Pb in the study area. In addition, no unexpected atmospheric or meteorological situations occurred which could have affected the parameters of this study. The Pb isotopic study results were similar to the ratios which have been determined for Mexico City, some cities in Russia and China with strong industrial activities and for the United States. This finding corroborates the hypothesis that Pb in Chihuahua City region has an anthropogenic origin, mainly smelting activities. The isotopic ratios for the indoor samples are somewhat larger than the corresponding outdoor isotopic Pb sample ratios. These data support the assumption that heavy metals, such as Pb, come from the resuspension of particulate matter from street dust and soil. The huge number of unpaved streets and the increasing vehicular movement among, other anthropogenic activities, are the direct and indirect causes of this environmental problem. [1] Mukai, H., Machida, T., Tanaka, A., Vera, Y. P., Uematsu, M. Atmospheric Environment 35 (2001) 2783-2793. [2] Bollhofer, A., Rosman, K. J. R. 2001. Geochimica et Cosmochimica Acta 65 (2001) 1727-1740. [3] Martínez, T., Lartigue, J., Juárez, F., Ávila-Perez, P., Zarazua, G., Márquez, C., Orta, M. P., Álvarez, V. Journal of Atmospheric Chemistry 49 (2004) 415-424. [4] Renberg, I., Brannvall, M. L., Bindler, R., Emteryd, O. The Science of the Total Environment 292 (2002) 45-54.
UNPA MESYRUM 2014
65
Study of conformational change cell wall proteins of Candida species during biofilm formation using STXM and FTIR techniques
Mayra Cuéllar-Cruza, Daniel Hernández-Cruzb and Enrique Rudiño-Piñerac
aDepartamento de Biología, División de Ciencias Naturales y Exactas. Campus Guanajuato. Universidad de Guanajuato. Guanajuato, C.P. 36050, México bFacultad de Ingeniería. Universidad Autónoma de Chiapas. Tuxtla Gutiérrez, C.P. 29050, México cInstituto de Biotecnología. Universidad Nacional Autónoma de México. Cuernavaca, C.P. 62210, México Email: [email protected] Keywords: Candida species; cell wall proteins; biofilm; synchrotron light Abstract Introduction and Aims The biofilms of Candida species are associated with high indices of hospital morbidity and mortality [1,2]. The main factors involved in the formation and growth of Candida biofilms are the chemical composition of the medical implant and the cell wall proteins (CWP), responsible for mediating the adhesion between Candida-Candida, Candida-human host cell, and Candida-medical device (Figure 1). To understand the mechanism by which the CWP change their structure during biofilm formation, tools from biology, physics and nanomaterials must be used. This analysis will facilitate the design of new nanomaterials and antifungal compounds to help eradicate this pathogen in nosocomial infections. In this work, using STXM and FTIR analysis techniques, we will determine the conformational change CWP of Candida during biofilm formation. This may enable the use of modified proteins for both diagnosis and better treatment of this mycosis. Originality Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) have been widely used to observe the biofilms of Candida and other microorganisms, just as X-ray diffraction has been used to the determine the three dimensional structure of proteins [1]. For Candida there are no reports of the three dimensional structure of the CWP involved in biofilms. This is probably due to the fact that crystallized proteins are required for X-ray diffraction, and these are not always feasible to recover. Nonetheless, SEM and CLSM images have made it possible to visualize the three-dimensional structure of Candida biofilms (Figure 2), and significant differences can be observed among the biofilms formed by the different species [1-3]. However, even though SEM and CLSM are key tools for visualizing the three-dimensional organization of biofilms, they are not able to elucidate the chemical interactions between Candida-Candida, Candida-surface and Candida-host cell, or to visualize the signaling molecules, the channels, or the proteins involved in the different phases of biofilm growth. It is essential to incorporate techniques such as STXM and FTIR that lead to understanding the chemical interactions between Candida-Candida, Candida-surface and Candida-host cell, as well as visualization of the signaling molecules, channels, and proteins involved during the different phases of biofilm growth. Future perspective Due to the large number of candidemias and systemic candidiasis associated with biofilm formation, it is urgent and indispensible to use new tools, like synchrotron radiation to develop medical devices with new materials that will reduce the high incidence of morbidity and mortality associated with these infections, and to increase the in vivo study of Candida cell wall proteins involved in adhesion and formation of biofilms on inert surfaces. This will facilitate the synthesis of new selective antifungals for Candida, which do not act on human cells. This can directly lead to the eventual eradication of biofilms from medical devices and a reduction in the morbidity and mortality associated with them.
UNPA MESYRUM 2014
66
References [1] M. Cuéllar-Cruz, E. López-Romero, J.C. Villagómez-Castro, E. Ruiz-Baca. Future Microbiology 7 (2012)
755-771. [2] CJ Nobile, AP Mitchell. Cell Microbiology 8 (2006) 1382-1391. [3] I. Serrano-Fujarte, E. López-Romero, G.E. Reyna-López, M.A. Martínez-Gámez, M. Cuéllar-Cruz. BioMed
Research International (2014) In Press.
Figure 1. Phases of Candida biofilm formation on medical devices. (A) Adherence of Candida by cell wall proteins to inert material. (B) Candida starts to proliferate. (C) Growth continues giving rise to the formation of mature biofilm, where Candida is protected from phagocytic cells, drugs, and toxic substances. (D) Finally, some of the fungal cells break off and colonize tissues or other implanted devices of the host.
Figure 2. Biofilms formed by Candida species as observed by SEM. Samples were observed with a LEICA F-420 SIGMA model, scanning electron microscope using a normal electrode SE detector at 10 kV under high vacuum conditions and at a working distance of 4 mm.
A
B
C
D
Drug
Proteins Ions
Phagocytic cells
UNPA MESYRUM 2014
67
SAXS studies to characterize the interaction of the ribosomal GTPase EFL1 and SBDS
Eugenio de la Mora, Abel Moreno and Nuria Sánchez-Puig
Instituto de Química, Universidad Nacional Autónoma de México. Av. Universidad 3000. Colonia UNAM México D.F. 04510, MEXICO.
Email: [email protected] Keywords: EFL1, ribosomal GTPase, SBDS, guanine nucleotides. Ribosomes are the molecular ribonucleoprotein machines responsible for protein synthesis. The eukaryotic ribosome is composed of two subunits, the large 60S subunit and the small 40S subunit. The yeast large ribosomal subunit consists of 46 ribosomal proteins and three rRNA (5.8S, 5S and 25S) while the small subunit contains only one rRNA (18S) and 33 ribosomal proteins. In yeast, an additional 200 accessory proteins and 75 small ribonucleoproteins (snoRNPs) have been shown to participate in the process (1-3). Ribosome biogenesis is closely linked to growth and cell proliferation and dysregulation of the process causes several diseases collectively known as ribosomopathies such as the Shwachman-Diamond Syndrome (4, 5). The SBDS protein mutated in this disease participates with EFL1 in the cytoplasmic maturation of the 60S subunit. The yeast orthologue is known as Sdo1. SBDS couples the energy liberated from the hydrolysis of GTP by EFL1 to release eIF6 from the surface of the 60S ribosomal subunit (6, 7). We have shown that the interaction of EFL1 with SBDS resulted in a decrease of the Michaelis-Menten (KM) constant for GTP and thus SBDS acts as a GEF for EFL1 (8). Moreover, binding kinetic studies established that specifically the SBDS protein diminishes the affinity of EFL1 for GDP increasing 60-fold the corresponding dissociation constant. We have studied the physical interaction between EFL1 and Sdo1 using different approaches. Models from the EFL1 and Sdo1 proteins were obtained from its homology with the elongation factor 2 (EF-2) and the archaea SBDS respectively. SAXS experiments (small angle x-ray scattering) were used to obtain the radius of gyration (Rg) of the complex, as well as, the proteins alone (Figure 1). At present, we are currently using the SAXS results together with information obtained from yeast two-hybrid and photocrosslinking experiments to generate a structural model of the complex formed between EFL1 and SBDS. Acknowledgements: The author (A.M. and N.S-P.) gratefully acknowledges financial support from CONACYT via the network: REDTULS. The authors also thank the Argonne/APS synchrotron beamline 18ID for the facilities offered during the SAXS experiments. References [1] Kressler D, Hurt E, Bassler J. Driving ribosome assembly. Biochim Biophys Acta 1803 (2010) 673-683. [2] Thomson E, Ferreira-Cerca S, Hurt E. Eukaryotic ribosome biogenesis at a glance. J Cell Sci 126 (2013) 4815-4821. [3] Woolford JLJ, Baserga SJ. Ribosome biogenesis in the yeast Saccharomyces cerevisiae. Genetics 195 (2013) 643-681. [4] McCann KL, Baserga SJ. Genetics. Mysterious ribosomopathies. Science 341 (2013) 849-850. [5] Teng T, Thomas G, Mercer CA. Growth control and ribosomopathies. Curr Opin Genet Dev 23 (2013) 63-71. [6] Finch AJ, Hilcenko C, Basse N, Drynan LF, Goyenechea B, Menne TF, González Fernández A, Simpson P, D'Santos CS, Arends MJ, Donadieu J, Bellanné-Chantelot C, Costanzo M, Boone C, McKenzie AN,Freund SM, Warren AJ. Uncoupling of GTP hydrolysis from eIF6 release on the ribosome causes Shwachman-Diamond syndrome. Genes Dev 25 (2011) 917-929. [7] Menne TF, Goyenechea B, Sánchez-Puig N, Wong CC, Tonkin LM, Ancliff PJ, Brost RL, Costanzo M, Boone C, Warren AJ. The Shwachman-Bodian-Diamond syndrome protein mediates translational activation of ribosomes in yeast. Nat Genet 39 (2007) 486-495. [8] Gijsbers A, Garcia-Marquez A, Luviano A, Sanchez-Puig N. Guanine nucleotide exchange in the ribosomal GTPase EFL1 is modulated by the protein mutated in the Shwachman-Diamond Syndrome. Biochem Biophys Res Commun 437 (2013) 349-354.
UNPA MESYRUM 2014
68
Figure 1. Gunier plots of A) EFL1, B) SBDS and C) the EFL1•SBDS complex.
ln(I)
-1
-0.8
-0.6
-0.4
s20.0005 0.001 0.0015 0.002
sub_001.dat Guinier Fit Residuals!"#$%
ln(I)
0.5
0.6
0.7
0.8
0.9
1
1.1
s20.0002 0.0004 0.0006 0.0008
sub_002.dat Guinier Fit Residuals!"#$
ln(I)
2
2.2
2.4
2.6
2.8
s20.0001 0.0002 0.0003 0.0004 0.0005
sub_004.dat Guinier Fit Residuals!"#$%&'#(
A
B
C
UNPA MESYRUM 2014
69
Synthesis and characterization of ZrO2: Sm3+ films prepared by Ultrasonic Spray Pyrolysis Technique.
R. Martínez-Martínez1, G. Juárez-López2, J.J. Carmona-Rodríguez1, I. E. Velázquez-Cruz3
G. Flores4, E. Zaleta-Alejandre5 and C. Falcony6. 1Instituto de Física y Matemáticas, 2Centro de Estudios de Nuevos Materiales, 3Instituto de Agroindustrias.
Universidad Tecnológica de la Mixteca. Carretera a Acatlima Km 2.5, C.P 69000. Huajuapan de León, Oax. México.
4CIDS-ICUAP Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 14 sur, Edif. 103C C.U., Col. San Manuel, Puebla 72570, México
5Universidad Autónoma del Estado de Hidalgo-Escuela Superior de Apan, Carretera Apan-Calpulalpan Km. 8, C.P. 43920, Apan, Hidalgo, México.
6Centro de Investigaciones y Estudios Avanzados del IPN, Departamento de Física, PO Box14-7400, 7000 México, DF, MéxicoEmail: [email protected]
Keywords: Photoluminescence, thin films, Spray Pyrolysis. Zirconium oxide has been commonly used due to its high refractive index, wide energy band gap, low optical loss, chemical and photochemical stability and excellent mechanical, electrical, thermal and optical properties [1]. Zirconium oxide has a high thermal expansion coefficient (10.2 x 10-6 °C-1), and low thermal conductivity (2.0 W mK-1) [2]. Wide band-gap (>5 eV) and low phonon energies (>650 cm-1) make it a promising host for doping with a wide range of luminescent impurities for operation at elevated temperatures [3]. It has been reported that pure ZrO2 presents low phonon energy, increasing the number and the probability of radiative transitions in rare earth doped samples [4]. It is well known that incorporated rare earth ions, usually in the divalent or trivalent states, have intense luminescence as a consequence of the 4f electronic transitions, with an emission energy that is almost independent of the host matrix. Photoluminescence (PL) of ZrO2: Sm3+ thin films were investigated, prepared by means Ultrasonic Spray Pyrolysis Technique. Photoluminescent spectrum bands were interpreted and their relation with preparation conditions was determined, such as: the spraying solution was 0.05M, samples were prepared adding different molar concentration of Sm3+ (0.25, 0.5, 1, 2.5, 5 and 7.5) %, the substrate temperature during deposition was in the range from 350 to 550 °C and deposition time was 7 min. The PL and excitation spectra of the ZrO2 doped with Sm3+ have been investigated. Under excitation optical pumping at 231 nm wavelength, the ZrO2: Sm3+ thin films shown dominant bands centred at (569, 619, 659 and 720) nm associated with electronic transitions (4G5/2 → 6H5/2, 4G5/2 → 6H7/2, 4G5/2 → 6H9/2, 4G5/2 → 6H11/2). The PL emissions have a strongest emission that occurs at 619 nm. Also, a quenching of the luminescence, with increasing doping concentration is observed. X-ray diffraction studies, as a function of the deposition temperature, indicate a tetragonal crystal structure of the zirconia when substrate temperature was increased. The chemical composition of the films was determined by energy dispersive spectroscopy. In addition, the surface morphology characteristics of the films, as a function of the deposition temperature, are presented. [1] F. Ramos-Brito1, H Murrieta S, J Hernández A, E Camarillo, M García-Hipólito, R Martínez-Martínez, O
Álvarez- Fragoso and C Falcony. Journal of Physics D: Applied Physics 39 (2006) 2079-2083. [2] F. Ramos-Brito, M García-Hipolito, R Martínez-Martínez, E Martínez-Sanchez and C Falcony. J. Phys. D:
Appl. Phys. 37 (2004) L13–L16. [3] M. Garcı ́a-Hipólito, R. Martínez, O. Alvarez-Fregoso, E. Martínez, C. Falcony. Journal of Luminescence
Volume 93 (2001) 9–15. [4] S. López-Romero, M. García-Hipólito, A. Aguilar-Castillo. World Journal of Condensed Matter Physics, 3
(2013), 173-179.
UNPA MESYRUM 2014
70
Figure 1. Figure 1. XRD diffractgrams for ZrO2:Sm3+ (2.5 a/o) films grown to Ts: 550°C.
Figure 2. Excitation spectra of ZrO2:Sm3+ (2.5 a/o) films grown at 550°C.
Figure 3. Photoluminescence emission spectra of ZrO2:Sm3+ films as a function of Sm3+ ions concentration.
Figure 4. Relative intensity of the emission peak centered at 620 nm of ZrO2:Sm3+ films as a function of the Sm3+ ions concentration.
UNPA MESYRUM 2014
71
Non-conventional techniques for protein crystallization and crystal growth
Nuria Sánchez-Puig1, Roberto Arreguín1, Jean Jakoncic2, Vivian Stojanoff2 and Abel Moreno1
1 Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Av. Universidad 3000, Ciudad Universitaria, C.P. 04510. Apdo. Postal 70250, México, D.F., México. 2 Brookhaven National Laboratory, National Synchrotron Light Source Bldg 725D, Upton New York 11873, United States.
Email: [email protected]
Keywords: Electric field protein crystallization, vapor diffusion.
Abstract: New strategies for protein crystallization either in solution or in gel using different devices that control the transport phenomena and crystal growth were studied [1]. A new easy-to-use device has been designed and implemented for electric-induced protein crystallization in a batch or vapor diffusion configurations (Figure 2). The device controls crystal nucleation by means of the electrical currentand also favors crystal growth due to its vapor diffusion set-up [2].The proteins investigated were Lysozyme, as model protein, and 2TEL-Lysozyme (a synthetic protein consisting of 2 tandem alpha helix motifs connected to a lysozyme) [3]. Protein crystals were obtained in shorter times in the presence of electric current compared to those grown in the absence of the electric field. Particularly, the analysis of the X-ray diffraction pattern of a test-case protein (2TEL-Lys) was qualitatively better when crystals were grown in the presence of electical current than in its absence. Other strategies such as the influence of magnetic field or temperature during protein crystallization were also tested. The crystal quality of glucose isomerase grown at different temperatures was evaluated using synchrotron radiation. Additionally, we applied a magnetic force of 11.75 Tesla (500 MHz) for the length of the nucleation period of two proteins SdsA and 2TEL-Lys using a classical spectroscopy NMR magnet. As evidenced in Figure 3 and Figure 4, the use of a magnetic field on the crystals of 2TEL-Lys and SdsA [4] resulted in the orientation of th crystals along the c axis which corresponds to the direction of the magnetic field. For the 2TEL-Lys protein the magnetic force had a more pronounced effect than for SdsA. Under batch conditions, the magnetic field favored the formation of crystallites perfectly aligned with the magnetic vector that otherwise were totally absent. Additionally, the use of the hydrogel together with magnetic force resulted in individual larger crystals compared to the clusters observed in the absence of magnetic field.
References
[1] Gil-Alvaradejo, G., Ruiz-Arellano, R. R., Owen, C., Rodriguez-Romero, A., Rudino-Pinera, E., Antwi, M. K., Stojanoff, V. & Moreno, A.Novel Protein Crystal Growth Electrochemical Cell for Applications in X-Ray Diffraction and Atomic Force Microscopy. Crystal Growth & Design11, (2011) 3917-3922. [2] Flores-Hérnandez, E., Stojanoff, V., Arreguín-Espinosa, R., Moreno, A., and Sánchez-Puig, N. An electrically assisted device for protein crystallization in a vapor diffusion set-up. Journal of Applied Crystallography46 (2013) 832-824. [3] Nauli, S., Farr, S., Lee, Y. J., Kim, H. Y., Faham, S. & Bowie, J. U. Polymer-driven crystallization. (2007). Protein Sci16, 2542-2551. [4]Hagelueken, G., Adams, T. M., Wiehlmann, L., Widow, U., Kolmar, H., Tummler, B., Heinz, D. W., Schubert, W.The crystal structure of of SdsA1, an alkylsulfatase from Pseudomonas aeruginosa, defines a third class of sulfatases. PNAS 103 (2006) 7631-7636.
UNPA MESYRUM 2014
72
Figure 2. Experimental design of the electrical device used for protein crystallization using a vapor diffusion set-up. A) Frontal view. B) Lateral view. Dark blue – front ITO glass. Ligth blue – rear ITO glass.
Figure 3. 2TEL-Lys crystals grown in a) batch in the presence of a magnetic field (500 MHz), b) crystals grown by counter-diffusion in polyvynil alcohol gel and c) crystals grown in by counter-diffusion in polyvynil alcohol gel in the presence of magnetic field (500 MHz). In the absence of magnetic field no crystal were obtained in batch. Scale bar = 100 µm.
UNPA MESYRUM 2014
73
Figure 4. SdsA crystals grown in a) solution (control) and b) in plyvynil alcohol gels in the presence of a strong
magnetic field of 11.75 Tesla (500 MHz). Scale bar = 300 µm.
UNPA MESYRUM 2014
74
Concrete deterioration and its relation with the environment.
T. Péreza, J. T. Pérez-Quirozb, M. Sosa-Baza.
aUniversidad Autónoma de Campeche bInstituto Mexicano del Transporte
Email: [email protected]
Keywords: Concrete, deterioration, environment. Reinforced concrete is the most used material of construction in the world. However, suffers deterioration due its interaction with aggressive agents present in surrounding as chloride ions in marine environment or CO2, SOx, NOx among others in urbane places. Cost associated with concrete corrosion is reported higher than 100 billions of dollars. Many researchers have been carried out studies focused to explain mechanisms between aggressive agents and the compounds of concrete. They have been found that the environmental conditions are determinant to promote the dynamics of penetration of substances across the net of porous in the concrete structure[1]. Advances of carbonation front and chloride into concrete, provokes secondary reactions and formation of compounds undesirables, which produces loss of chemical properties as changes in pH and mechanicals because these compounds do not have same bonding characteristics. Recently, the climatic change induced by global warming effect over the concrete durability has been studied, remarking the influence of increasing of temperature over the wet-dry cycles in porous net and diffusion of aggressive substances toward inner the concrete[2, 3]. Tuuti´s model of service life of concrete structures consists of two parts: initiation and propagation. The initiation step is the time to takes to aggressive agents to advance across the concrete bulk until reach a threshold to depassivate the rebar and start the corrosion process. The importance to study this phenomenon is understand the mechanisms that carry out to allow predict stages of deterioration opportunely and take preventive actions to extend life time useful for concrete structures and avoid costs due maintenance, repair and rehabilitation. Deterioration process is very complex, because include combination of action and synergism of environmental parameters and properties of concrete across time. Monitoring of deterioration of reinforced concrete has been done with measurements in the laboratory as in the field. Both types of research have used diverse techniques. For properties of bulk, physical tests as compressive force, porosity, superficial hardness, gas permeability, liquid permeability, density and electrical resistivity among others[1]. Chemical changes are determined by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier Transformed Infrared (FTIR), Differential Thermal Analysis (DTA), Thermogravimetric Analysis (TGA) and others[4]. For the interface concrete-steel electrochemical tests as Half Cell Potential (HCP), Linear Polarization Resistance (LPR), Polarization Curves (PC), Electrochemical Noise (EN), Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV), among others[5]. Also, to identify compounds formed over the steel are employed every techniques mentioned for the bulk analysis. Besides, for natural exposure, is pertinent carry out measurements of meteorological parameters as Temperature, Relative Humidity (RH), Rain Precipitation (RP), Wind Direction (WD), Wind Velocity (WV), as well as natural aggressive substances as chlorides in coastal zone and CO2, and anthropogenic contaminants as SO2 and NOx that origin acid rain, very harmful to concrete[6]. Adequate inspection plan must include as techniques as possible, but everybody finds limitations in infrastructure capacity, which leads to look for entailment with collaborators who partake of similar studies and interests. A success way to achieve the objectives and completes investigations, is through formation of networks, where integration of human and infrastructure capabilities become a synergistic work team. In spite of the wide amount of techniques used, the concrete deterioration has not been understood completely due the complexity of processes involved. Each technique contributes particular data, which form part of knowledge reported. By this reason, is important carry out new experimental options to generate information to increase knowledge in the present theme. We expect that sincrotron tests generate unpublished information, specially focused to clear up mechanisms at molecular level, as chloride reaction with cement components,
UNPA MESYRUM 2014
75
during curing as well as the period of hardening and samples that have been exposed. Also, explain the sequence of reactions in the porous solution of concrete due to the carbonation process. Besides, characterize compounds formed over the steel surface and understand the corrosion mechanisms that originate internal cracks in the concrete paste. Figures 1 and 2 show results of two techniques used to study the concrete deterioration. Figure 1shows the use of SEM to analyze distribution of elements at interface concrete-steel. Figure 2 shows the depassivation of rebar embedded concrete by using EIS. Information generated will be a great help for construction industry, both for research and in the field application, because may be become used as base to fabricate a new formulation of cements as well as dosage to obtain a durable concrete. References. [1] O. Trocónis de Rincón (Ed.), DURAR Network Members, Manual for Inspecting, Evaluating and Diagnosing Corrosion in Reinforced Concrete Structures. CYTED. Maracaibo, Venezuela. 1997/1998/2001 (1st Edition, 2nd Edition and 3rd Edition in Spanish). 2000 (1st Edition in English). [2] E. B. Pereira de Castro, M. Mequignon, L. Adolphe, P. Koptschitz. Energy and Buildings 76 (2014) 228–237. [3] P. Castro-Borges, J. M. Mendoza-Rangel. Corrosion Engineering, Science and Technology 45 (2010) 61-69. [4] M. Sosa, T. Pérez-López, J. Reyes, F. Corvo, R. Camacho-Chab, P. Quintana, D. Aguilar. International Journal of Electrochemical Science 6 (2011) 6300–6318. [5] Sagüés, A. “Corrosion measurement techniques for steel in concrete”. Corrosion 93, NACE, Paper No. 353. [6] Trocónis de Rincón, O., et al. "Effect of the marine environment on reinforced concrete durability in Iberoamerican countries: DURACON project/CYTED."Corrosion science 49.7 (2007): 2832-2843.
Chloride Iron Oxigen Figure 1. Elemental Analysis of interface concrete-steel
UNPA MESYRUM 2014
76
Figure 2. Monitorig of the depassivation of steel rebar embedded in concrete by using EIS.
UNPA MESYRUM 2014
77
Apply Smart Sensitivity Control withAgilent’s New Range of S2 CCD Detectors
Daniel Baker a, Fraser White a, Zolt.nG.la, Mathias Meyer b, PrzemysławStecb, Angel Sanzc
aAgilent Technologies UK Ltd., 10 Mead Road, Oxford Industrial Park, Yarnton, Oxfordshire, OX5 1QU, UK. bAgilent Technologies Sp. z o. o., Szarskiego 3, 54-610, Wrocław, Poland
cDiffractia México S. de R.L. de C.V., México D.F., 03100, México
Email: [email protected] Keywords: S2 CCD, Binning, Smart Sensitivity Control, Noise level, Dynamic Range X-ray detector technologiesvaryfrom discipline to discipline dependingonthespecificcharacteristics of thesamples, thetype of X-raysourcebeingused, and thelevel of precisionrequiredfortheobserved data. X-raycrystallographyrequiresdetectorswhichofferhighsensitivity, widedynamicrange, and mostcritically, lownoisetoensurethatanaccuratemeasurement of rawdiffractionintensitiesispossibleevenwhensignalisweak. Agilent Technologies haveproduced a range of novel and uniquedetectorswhichautomatically tune theirmeasurementsettingsbasedonthesampleprovided; fullyoptimizing data qualitylike no other detector can in X-rayCrystallography. The S2 CCD serie,Eos S2, Atlas S2, and Titan S2allfeaturestate-of-the-art electronics, unique Smart Sensitivity Control (SSC), and instant-switching of binningmodesthatgivesyouthemost flexible detectorsforyourapplications.
Figure 1. Using SSC in high mode for extremely week data enables the weakest reflections to be observed in like-for-like experiments
UNPA MESYRUM 2014
78
Figure 2. Flexible binning provides the best of both worlds: better sensitivity where data are weak (for example, 4x4 binning for high angle data) and high dynamic range when data are strong (for example, 2x2 binning for low angle data)
Figure 3. Extremely low noise level as observed from a 1 hour exposure with the Titan S2 CCD detector (standard operation without X-rays). The image is displayed on the photon level
UNPA MESYRUM 2014
79
Lyase activity of glycogen synthase: Is an elimination/addition mechanism a possible reaction pathway for retaining glycosyltransferases?
Adelaida Díaz a, Mireia Díaz-Lobo a, Enrique Grados b, Joan J. Guinovart a, Ignacio Fita c and Joan C. Ferrer b.
a Institute for Research in Biomedicine (IRB Barcelona), Barcelona, 08028, Spain
b Universitat de Barcelona, Barcelona, 08028, Spain c Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC),
Barcelona, 08028, Spain Email: [email protected]
Keywords: glycogen synthase, catalytic mechanism, 1,5-anhydro-D-fructose, protein structure Glycosyltransferases (GTs) catalyze the stereo-specific transfer of monosaccharide units from activated glycosyl donors, usually nucleotide sugars, to suitable acceptors, such as saccharides, proteins, DNA, lipids and natural products. The glycans and glycoconjugates resulting from GTs catalytic activity play essential roles in carbon and energy metabolism, cellular and molecular recognition, signal transduction, cell wall formation and pathogenesis [1]. Such a range of biological functions makes these enzymes attractive therapeutic targets, for which the rational design of specific inhibitors would benefit from a detailed knowledge of their catalytic mechanism.
Despite the biological relevance of GTs and the many efforts devoted to this subject, the catalytic mechanism through which a subclass of this large family of enzymes, namely those that operate with net retention of the anomeric configuration, has not been fully established.
Here, we show that in the absence of an acceptor, an archetypal retaining GT such as Pyrococcus abyssi glycogen synthase (PaGS) reacts with its glucosyl donor substrate, uridine 5'-diphosphoglucose (UDP-Glc), to produce the scission of the covalent bond between the terminal phosphate oxygen of UDP and the sugar ring. The crystal structure of the complex between UDP-Glc and PaGS showed in the active site of one of the three monomers of the enzyme an electronic density, which resembled that of a glucose molecule lacking the exocyclic oxygen attached to the anomeric carbon, while no density attributable to the UDP moiety was found (Figure 1). Chemical derivatization followed by gas chromatography/mass spectrometry of the isolated glucose-like species allowed us to identify the molecule found in the catalytic site of PaGS as 1,5-anhydro-D-arabino-hex-1-enitol (AA) or its tautomeric form, 1,5-anhydro-D-fructose (Figure 2). These findings are consistent with a stepwise SNi-like mechanism as the modus operandi of retaining GTs, a mechanism that involves the discrete existence of an oxocarbenium intermediate. Even in the absence of a glucosyl acceptor, glycogen synthase (GS) promotes the formation of the cationic intermediate, which, by eliminating the proton of the adjacent C2 carbon atom, yields AA. Alternatively, these observations could be interpreted assuming that AA is a true intermediate in the reaction pathway of GS and that this enzyme operates through an elimination/addition mechanism [2].
[1] N. Taniguchi, K. Honke, M. Fukuda. Handbook of Glycosyltransferases and related genes. Springer, Tokyo.
2002. [2] A. Díaz, M. Díaz-Lobo, E. Grados, J. J. Guinovart, I. Fita, J. C. Ferrer. IUBMB Life 64 (2012) 649-658.
UNPA MESYRUM 2014
80
Figure 1. Observed electron density (2Fobs – Fcalc, contoured at 1.0 σ level, in divergent “wall eyed” stereo) of the PaGS active site (in
green residues of the N domain and in orange of the C domain) showing a modelled 1,5-anhydro-D-fructose molecule (AF, grey). It should be noted that AF, 1,5-anhydro-D-arabino-hex-1-enitol (AA), or a mixure of both can account for the electron density
observed.
Figure 2. Mass spectra of the pertrimethylsilyl-2-ethyloxyimino derivative (1) of an authentic sample of 1,5-anhydrofructose (A)
and the corresponding material extracted from the reaction between PaGS and UDP-Glc (B).
UNPA MESYRUM 2014
81
Electrochemical Analysis of Pt chalcogenides synthesized by a dispersion method
Adriana Sigüenza Orozco a, Zaira Itzel Bedolla Valdezb, María de Jesús Gil Gallegosa, Yadira Gochi Poncea
a Instituto Tecnológico de Oaxaca, División de Estudios de Posgrado e Investigación, Oaxaca, Oaxaca, C. P. 68030, México
b Centro de Nanociencias y Nanotecnología-UNAM, Ensenada, Baja California, C. P. 22800, México Email: [email protected]
Keywords: PEMFC, platinum chalcogenide, electrocatalyst, voltammetry, oxygen reduction reaction. The catalytic materials research for the cathode of the proton exchange membrane fuel cell (PEMFC) focuses on reducing the platinum content in the fuel cell, the transition metal chalcogenides are materials that exhibit good electrocatalytic activities for oxygen reduction [1]. In this work, two Platinum chalcogenides catalytic precursors were synthesized by chalcogen dispersion method using sulfur and selenium powders[2], the obtained materials were heat treated and analyzed by cyclic voltammetry. The precursors were prepared as follows. To synthesize Pt-S material, a solution of ammonium hexachloroplatinate and sulfur powder (molar ratio 1:1) in water was continuously stirred at 600 rpm for 12 hours at room temperature. Subsequently, the precipitate was washed with deionized water and dried at 60 °C. Afterward, the material was thermally treated at 360 °C under inert atmosphere for 2 hours [2]. A similar procedure was followed to prepare Pt-Se, selenium powder was used instead sulfur powder and the stirring was keeping for 24 hours. Once the thermal treatment was performed inks were prepared; 1 mg of the sample material was dissolved in a mixture of 5.63 µL of deionized water, 1.88 µL of nafion and 73µL of isopropyl alcohol (concentration 12.42 g/L), both mixtures were homogenized by sonication during 1 hour. A 2µL aliquot of each sample were deposited on glassy carbon electrodes and dried at room temperature, in addition to these, a Pt/Vulcan (Pt/V) ink was prepared at same conditions. Electrochemical measurements of the catalytic precursors were performed by cyclic and linear voltammetry in 0.5 M H2SO4 solution in a three-electrode electrochemical cell, the scan rate was 20 mV/s, the reference electrode was Ag/AgCl, the linear voltammetry was performed at a rotation speed of 1500 rpm. Comparing the obtained voltammetries for the synthesized materials with the Pt/V voltammetry. It is observed the presence of the peak at a voltage of 1.44 V in the three materials (Figure 1-3), this peak indicates the formation of oxides on platinum surface [3]. The peak in the Pt-S material (Figure 2) was observed very similar to the Pt/V (Figure 1). On the other hand, in Pt-Se material (Figure 3) the peak is observed partially suppressed and also another peak appears at a voltage of 1.15 V which is attributed to the presence of the chalcogen [4]. Moreover for Pt/V electrocatalyst, the oxygen reduction region is observed between 0.2 to 0.6 V, this region is similar to the Pt-S material, however, for Pt-S a suppressed peak is observed in relation to Pt/V; for the Pt-Se material reduction region is displaced towards the left and comprises from 0.0 to 0.6 V, the displacement is attributed to the presence of the chalcogen, also can be seen that the peak shows slightly suppressed in comparison with Pt/V. The region between -0.2 and 0.0 V shows the adsorption and desorption of hydrogen, for Pt-S material the peaks are similar to those shown by Pt/V [3]. Nevertheless, these peaks are observed slightly suppressed with respect to Pt/V; on the other hand, in Pt-Se material the peaks are completely suppressed in this range of voltages, also adsorption and desorption peaks are observed below -0.2 V, indicating that Se modifies the electrocatalyst surface, similar to researches reported before [2, 3]. Figure 4 shows the comparison between the linear voltammetries of the synthesized materials and platinum, it is observed that the Pt-S material appears like the Pt/V behavior, in both the area of kinetic control is observed between 0.6 and 0.55 V, which suggests that Pt-S has a higher electrocatalytic activity for the ORR than Pt-Se, the performance for generating current density of Pt-S was 71.5% compared to Pt/V unlike the Pt-Se having an efficiency of 44.2%.
UNPA MESYRUM 2014
82
Once known the electrochemical behavior of the materials is necessary to perform further characterizations to determine the composition and materials structure,, physical techniques such as XRD, TEM, SEM and others are required to characterize these materials and understand their structures to explain their behavior. [1] A. Brouzgou, S. Q. Song, P. Tsiakaras. Applied Catalysis B: Enviromental 127 (2012) 371-388. [2] Y. Gochi-Ponce, G. Alonso Nuñez, N. Alonso Vante. Electrochemistry Communications 8 (2006) 1487-
1491. [3] A. A. Arango Perdomo, Estudio y aplicación de nanoestructuras de calcogenuros, PhD Thesis, División de
estudios de Posgrado e Investigación, Instituto Tecnológico de Oaxaca, Oaxaca, Junio (2013), 61pp. [4] D. Cao, A. Wieckowski, J. Inukai, N. Alonso-Vante. Journal of The Electrochemical Society 153 (2006)
A869-A874.
Figure 1. Cyclic voltammetry of Pt/Vulcan in 0.5M H2SO4 and 20mV/s
Figure 2. Cyclic voltammetry of Pt-S material in 0.5M H2SO4 and 20mV/s
Figure 3. Cyclic voltammetry of Pt-Se material in 0.5M H2SO4 and 20mV/s
-‐4.00E-‐04 -‐2.00E-‐04 0.00E+00 2.00E-‐04 4.00E-‐04 6.00E-‐04 8.00E-‐04 1.00E-‐03
-‐0.5 0 0.5 1 1.5 2
Curren
t Den
sity (A)
Poten=al (V vs Ag/AgCl) -‐4.00E-‐04
-‐2.00E-‐04
0.00E+00
2.00E-‐04
4.00E-‐04
6.00E-‐04
8.00E-‐04
1.00E-‐03
-‐0.4 -‐0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Curren
t Den
sity (A)
Poten=al (V vs Ag/AgCl)
-‐4.00E-‐04
-‐2.00E-‐04
0.00E+00
2.00E-‐04
4.00E-‐04
6.00E-‐04
8.00E-‐04
-‐0.4 -‐0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Curren
t Den
sity (A)
Poten=al (V vs Ag/AgCl)
UNPA MESYRUM 2014
83
Figure 4. Linear voltammograms of Pt-S, Pt-Se and Pt/Vulcan in 0.5M H2SO4 and at 20mV/s
UNPA MESYRUM 2014
84
NANOMATERIALS FOR LEUKEMIA STUDY: AN OPORTUNITY FOR SYNCHROTRON LIGHT TO CHARACTERIZE GOLD NANOSTARS
Juan C. Martínez-Espinosa b, José de Jesus Ibarra-Sanchez a, Ana Karen Zavala Raya b, V. H. Romero c, Miguel
José Yacaman d, M. Guadalupe de la Rosa Álvarez a
a DCI, Universidad de Guanajuato, Campus León, León, Guanajuato, 37150, Mexico.
b UPIIG, Instituto Politécnico Nacional, Silao de la Victoria, Guanajuato, Mexico. c Universidad de Guadalajara-CUT, Tonalá, Jalisco, 45400, México.
d University of Texas, San Antonio, Texas, 78249, EUA. Email: [email protected]
Keywords: Biomaterials, Leukemia, Syncrotron light. Abstract: We characterized gold nanoparticles (NP’s) with star shape. We obtained a hydrodynamic diameter distribution of 116.4 ± 26.92 nm. Preliminary results suggest apply SERS technique for lymphocyte B classification in the studying the leukemia and explore new techniques to characterize physicochemical properties of gold nanostars by using synchrotron light Results: SEM images showed star shaped with homogenous sized around 116.4 ± 26.92 nm. Likewise, the nanomaterials synthesized in this way were functional. (See figure 1). The ratios of some band intensities were analyzed and some of them resulted significant and corresponded to proteins, phospholipids, aminoacids and polysaccharides. The spectra from the samples conjugated with two markers where different in the peaks 632, 1047, 1110, 1231 and 1452 cm-1. (See figure 2). The spectrum block for CD10 and CD19 antibody were evaluated by principal component analysis. Principal components scores comparing CD10+ and CD19+ groups showed that there were most significant PC’s (PC1, PC2 and PC3). To illustrate a three-dimensional scatter plot of using three PC’s as axes are presented in figure 3. Preliminary results, suggests that it’s possible to differentiate between this two markers and since they appear during different stages of the maturation of the B cells, making possible to distinguish between healthy patients and leukemia subjects, depending on the concentration of the antigen in the sample. The use of nanostars for biomedical applications gives a opportunities field for to continue work in this research area and find an alternative treatment and therapeutic for blood cancer. These preliminary results open new fields of opportunity to explore techniques of characterization in parallel as is synchrotron light. In which we can use to study the physical and chemical properties of gold nanostars [1] Fischlechner M., Donath E. Angew Chem lnt Ed 2007, 46:3184-3193. [2] Marie, Ch.;Didier, A., Chem. Rev., 104, 293-346, (2004). [3] Diandra, L.; Reuben, D., Chem. Mater., 8(8), 1770-1783, (1996). [4] John, M.T., Pure & Appl. Chem., 60, 1517-1528, (1988). [5] Klaus, E.; Marion, L.; Martin, M., Matthias, P.; Helmut, S., Method for manufacturing substrateswith
transparent and color coating stable at high temperature and in the presence of ultraviolet rays, [6] U.S. Patent, 6156388, Dec. 5, (2000). [7] Bing, T.; Yiying, W., J. Phys. Chem.. B, 110, 15932-15938, (2006). [8] Frank, C. Adv. Mater., 13, 11-22, (2001).
UNPA MESYRUM 2014
85
Figure 1. NP’s synthesized from gold seed. Left: hydrodynamic diameter distribution for golden seed. Right: SEM image of the synthesized nanoparticles.
Figure 2. Raman Spectra of the samples coated with the protein. Left side CD19 surface marker.
Figure 3. 3D plot of the PC1 versus PC2 versus PC3 for Anti-CD10+ versus Anti-CD19+.
UNPA MESYRUM 2014
86
Texture determination of ZnO nanorods using 2D synchrotron diffraction and its simulation by ANAELU.
A. Sáenz-Trevizo, L. Fuentes-Cobas, P. Amézaga-Madrid, P. Pizá-Ruíz, W. Antúnez-Flores and M. Miki-
Yoshida*
Departamento de Física de Materiales, Centro de Investigación en Materiales Avanzados, S.C., Chihuahua,
Chihuahua, 31136, México.
*Email: [email protected]
Keywords: ZnO nanorods, texture, 2D diffraction, ANAELU. Abstract. Materials properties such as optical, mechanical and electrical depend on their microstructure, i.e. crystalline structure, crystallite size, chemical composition and other morphological characteristics such as shape, dimensions or orientation [1-3]. As an example, nanorods based solar cells, are a desired morphology because it provides a larger surface to volume ratio. Besides, the device performance could be enhanced if the axis orientation of the material can be controlled and optimized. Common techniques for the determination of materials orientation, known also as texture, result from the interpretation of conventional x-ray diffraction outcomes [2], the determination of the Lotgering factor [4] or through a combination of methods [3]. However, the study and interpretation of the poles figures is the most accurate way to define the crystalline arrangement of a desired material [3, 5]. This work reports the theoretical and experimental texture analysis of ZnO nanorods grown over TiO2 thin film coated borosilicate substrates, by the aerosol assisted CVD technique using a similar set up reported elsewhere [6]. Figure 1 shows a secondary electron SEM micrographofa dense layer of ZnO nanorods.Two dimensional synchrotron diffraction (2D-SD) was used to stablish the texture of the samples, it was complemented with conventional x-ray diffraction using Bragg-Brentano and grazing incidence configurations. ANAELU software [7, 8], which comprises the analysis of poles figures, allowed to the determination of nanorods texture by fitting experimental 2D-SD (Figure 2a) and simulated diffractograms (Figure 2b).Texture analysis led to the conclusion of relatively vertically oriented nanorods with a [001] preferred growth direction, having a distribution width of Ω = 20 ± 2º relative to the substrate normal. This result was consistent with those of x-ray diffraction in Bragg-Brentano and grazing incidence configurations, which showed that a significant number of nanorods had its axis inclined at γ≅ 17.2º to the substrate normal and other important amount of nanorods, exhibited its axis perpendicular to the substrate’s surface (γ≅ 0º). An average nanorods axis inclination relative to substrate normal of -4 ± 23° (clockwise direction +) was determined by the study of cross sectional morphology of the samples by field emission scanning electron microscopy (Figure 3); consistent with diffraction results. These outcomes proved that within the combination of 2D synchrotron diffraction methods and computational modeling by ANAELU, a reliable and proper texture definition of ZnO nanorods can be determined.
[1]. B.R. Mehta and F.E. Kruis.Sol Energ Mat Sol C 2005; 85, 107-113. [2]. C.Y. Dwivediand V. Dutta. Adv Nat Sci: NanosciNanotechnol 2012;3, 015011-015019. [3]. D. Ariosa, F. Elhordoy,E.A. Dalchiele, R.E.Marottiand C. Stari. J ApplPhys 2011; 110, 124901-
124909. [4]. F. Solís-Pomar, E. Martínez, M.F. Meléndrez and E. Pérez-Tijerina. Nano Res Lett 2011; 6, 524-535. [5]. K.H. Brosnan, G.L. Messing, R.J. Meyer and M.D.J. Vaudin. Am Ceram Soc 2006; 89: 6, 1965-1971. [6]. A. Sáenz-Trevizo, P. Amézaga-Madrid, P. Pizá-Ruíz, O. Solís-Canto, C. Ornelas-Gutiérez, S. Pérez-
García and M. Miki-Yoshida. J Alloys Compd 2014; 615: 1, S375-S381. [7]. http://cimav.edu.mx/investigacion/software/anaelu. Updated: October 19, 2010. [8]. L. Fuentes-Montero, M.E. Montero-Cabrera and L. Fuentes-Cobas. J Appl Crystallogr 2011; 44, 241-
246.
UNPA MESYRUM 2014
87
Fig. 2. Two dimensional synchrotron diffraction results. a) experimental 2D-‐SD diffractogram of sample shown in Fig. 1.b) simulated diffractogram with ANAELU. A clear correspondence indicates a proper determination of the [001] preferred growth direction, having a distribution width of Ω = 20 ± 2º relative to the substrate normal.
Fig. 3. Typical cross sectional SEM micrograph ofZnO nanorods sample.An average nanorods axis inclinationof -‐4 ± 23° (clockwise direction +), respect to the substrate’s normal, was determined analyzing several micrographs. This resultand that of 2D-‐SD are in good agreement; proving that the combined method led to a reliable texture determination.
Fig. 1. Secondary electron SEM micrographofa dense layer of ZnOnanorodscovering the TiO2 thin film coated borosilicate substrate.
UNPA MESYRUM 2014
88
TEM analysis of Cux(CdTe)yOz thin films
A. Miguel-Hernándeza, P. del Angel-Vicenteb, S. Jiménez-Sandovalc, R. Lozada-Moralesd, J. A. Montoya de la Fuenteb,
O. Jiménez-Sandovalc, R. Martinez-Martineza, G. Juarez-Lopeza, J. Carmona-Rodrígueza
a Instituto de Física y Matemáticas, Universidad Tecnológica de la Mixteca, Carretera a Acatlima Km. 2.5, Huajuapan de León, Oax C.P. 69000, México
b Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas 152, México, D.F., 07730, México. c Centro de Investigación y de Estudios Avanzados del I.P.N., Unidad Querétaro, Apartado Postal 1-798,
Querétaro, Qro., 76001, México. d Benemérita Universidad Autónoma de Puebla, Postgrado en Física Aplicada, Facultad de Ciencias Físico-
Matemáticas, Av. San Claudio y Av. 18 Sur, Col. San Manuel, Ciudad Universitaria, Puebla, Pue C. P. 72570, México
Email: [email protected]
Keywords: Cux(CdTe)yOz, TEM, XRD Study of materials with applications in photovoltaic devices is of great interest due to the necessity to increase the conversion efficiency and lower production costs. CdTe has generated great expectation for application as an absorbent layer in solar cells due to it shows higher values of absorption coefficient and a bandgap of 1.5eV, which is close to ideal values theoretically calculated. However, pure CdTe has a high resistivity value, thus it is necessary the doping to increase the conductivity. In recent years, the system Cux(CdTe)yOz ( CCTO ), which is a possible candidate to substitute to CdTe, has been investigated for S. Jiménez- Sandoval[1-6]. In these studies it was observed that the values of the band gap width can be tailored from 1.5 to 3.0eV and structurally it is possible to obtain polycrystalline or amorphous thin films depending on the amounts incorporated of Cu and O. In this work Cux(CdTe)yOz thin films were grown by co-sputtering reactive. The samples were prepared in a chamber with an atmosphere of a mixture of Ar/O. CdTe and Cu targets were eroded with 35 and 10-40 Watts respectively. Substrate temperature was kept at 400oC for all the samples. Microstructure of the samples was analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns show that all the samples were polycrystalline with the presence of the characteristic peak of CdTe (111C/002 H). However when Cu content is increased, this peak is asymmetric due to formation of Cu2Te. On the other hand, from XRD was not possible to find evidence of tellurium oxides in the thin films, however by TEM analysis it was observed the presence of different oxides and sub-oxides of tellurium. Finally, all regions show high density of structural defects due to grain boundaries. [1] S. Jimenez-Sandoval, J. Santos-Cruz, GE Garnett-Ruiz, R. Castanedo-Perez, G. Torres-Delgado, O.
Jimenez-Sandoval. Journal of Cristal Growth 294 (2006) 243-249. [2] S. Jimenez-Sandoval, GE Garnett-Ruiz, J. Santos-Cruz, O. Jimenez-Sandoval, G. Torres-Delgado, R.
Castanedo-Perez, E. Morales-Sanchez. Journal of Applied Physics 100 (2006) 113713. [3] S. Jimenez-Sandoval, J. Carmona-Rodriguez, R. Lozada-Morales, O. Jimenez-Sandoval, M. Melendez-Lira,
CI Zuniga-Romero, D. Dahlberg. Solar Energy Materials and Solar Cells 90 (2006) 2248-2254. [4] J. Carmona-Rodriguez, R. Lozada-Morales, P. del Angel-Vicente, O. Jimenez-Sandoval, G. Lopez-Calzada,
D. Dahlberg, S. Jimenez-Sandoval. Journal of Materials Chemistry 21 (2011) 13001-13008. [5] A. Mendoza-Galvan, S. Jimenez-Sandoval, J. Carmona-Rodriguez. Thin Solid Films 519 (2011) 2899-2902. [6] G. Arreola-Jardon, S. Jimenez-Sandoval, A. Mendoza-Galvan. Vacuum 101 (2014) 130-135.
UNPA MESYRUM 2014
89
Table 1. Labels and growth parameters Sample rf-power
(Watts) Ar flow (sccm)
O flow (sccm)
CCTO-1 10
12 11 CCTO-2 20 CCTO-3 30 CCTO-4 40
20 30 40 50
C C C T O -‐4
C C C T O -‐3
C C C T O -‐2
2θ (deg ree)
C C T O -‐1
Figure 1. XRD for the thin films with different powers of Cu
Figure 2. TEM image for the sample CCTO-4
UNPA MESYRUM 2014
90
Use of synchrotron infrared microspectroscopy for molecular identification of useful products obtained from lignocelulosic materials pretreated with steam explosion.
Carlos Molinaa, Arturo Sánchezb, Idania Valdez-Vazquezc, Delfino Franciad, Graciela Ruiz-Aguilard, Guadalupe
de la Rosa Álvareza*. aDepto. de Ingeniería Química, Electrónica y Biomédica, Universidad de Guanajuato. Loma del Bosque 103,
Col. Loma del Campestre, León, 37150, Guanajuato, México. bCINVESTAV - IPN. Unidad de Ingeniería Avanzada, Av. del Bosque 1145, colonia el Bajío, Zapopan, 45019,
Jalisco, México. cUnidad Académica Juriquilla, Instituto de Ingeniería. UNAM. Blvd. Juriquilla 3001, Juriquilla, 76230,
Santiago de Querétaro, Qro. México. dDepto. de Ciencias Ambiéntales , DICIVA, Universidad de Guanajuato, Carretera Irapuato-Silao Km 9.0,
36500, El Copal, Irapuato, Mexico
ABSTRACT Lignocellulosic biofuels can be produced from materials such as agro-wastes (i.e., wheat straw), forage residues (i.e., softwood), etc., under a biochemical platform which comprises four fundamental steps: (i) pretreatment, (ii) hydrolysis, (iii) fermentation and (iv) downstream processes1. In this context, pretreatment process is performed in order to separate the three principal components of lignocelulosic materials: cellulose, hemicellulose and lignin. One of these pretreatments is steam explosion which consist in exposing lignocellulose to high temperatures and pressures. In this process it is possible to obtain a certain degree of delignification. The structure of lignin can be transformed to useful products depending on the temperatures and pressures used in this pretreatment. Lignin is now considered as the main aromatic renewable resource. It represents an excellent alternative feedstock for the elaboration of chemicals and polymers. Lignin is a highly abundant biopolymeric material that constitutes, in addition to cellulose, one of the major components in structural cell walls of higher vascular plants. Large quantities of lignin are yearly available from numerous pulping processes such as paper and biorefinery industries. Lignin extraction from lignocellulosic biomass (wood, annual plant) represents the key point to its large use for industrial applications. One of the major problems still remains is its unclearly defined structure and its versatility according to the origin, separation and fragmentation processes, which mainly limits its utilization. While currently often used as a filler or additive, lignin is rarely exploited as a raw material for chemical production. However, it may be an excellent candidate for chemical modifications and reactions due to its highly functional character (i.e., rich in phenolic and aliphatic hydroxyl groups) for the development of new biobased materials2. This work proposes the use of synchrotron radiation, particularly IR, with the objective of identifying the different useful products that can be obtained from the lignin decomposition under several operative condition (temperature and pressure), with steam explosion pretreatment of WS in range the of 60 lb/in2 to 600 lb/in2. 1Sánchez A. Sevilla-Güitrón V., Magaña G., Gutierrez L. (2013). Parametric analysis of total costs and energy efficiency of 2G enzymatic ethanol production. Fuel; 113: 165–179. 2Laurichesse S., Avérous L. (2014). Chemical modification of lignins: Towards biobased polymers. Progress in Polymer Science, 39; 1266–1290.
UNPA MESYRUM 2014
91
COMPARATION OF LEAD AND CADMIUM ACCUMULATION BY TYPHA LATIFOLIA (ESPADAÑA) AND PISTIA STRATIOTES (WATER LETTUCE)
Claudia E. Moctezuma-Granados1, Alejandro Hernandez-Morales1, Candy Carranza-Álvarez1
1 Unidad Académica Multidisciplinaria Zona Huasteca, Universidad Autónoma de San Luis Potosí, Calle Romualdo del Campo No. 501, Frac. Rafael Curiel, Cd. Valles, S.L.P., C.P. 79060, México.
Email: [email protected]
Keywords: phytoremediation, heavy metals, accumulation, T. latifolia, Pistia stratiotes. Abstract The removal from the solution and the accumulation of Pb and Cd by Typha latifolia (cattail) and Pistia stratiotes (water lettuce) was studied and compared. Small plants of T. latifolia and Pistia stratiotes collected from a non-contaminated site, were exposed to individual concentrations of Pb (II) and Cd (II) for 10 days. To do this, T. latifolia and P. stratiotes were washed with water and EDTA to remove any metals adsorbed onto the root. At the end of the experimental days, the plants were removed from the solutions and sectioned into root, stem and leaf. The plant material was dried and subjected to acid digestion process. Finally, the Pb (II) and Cd (II) were measured by atomic absorption spectrophotometry (AAS) with flame method for determining the accumulation of lead and cadmium. The results showed that the accumulation of Pb (II) and Cd (II) was found primarily in the root tissue for both plant species T. latifolia plant being presented with a greater accumulation. The results suggest that T. latifolia and P. stratiotes can be considered as an interesting alternative for treating aquatic effluents polluted with toxic trace elements. Introduction As a result of industrialization and increasing world population, the concentration of toxic elements in the water, air and soil has increased. Heavy metals are considered priority pollutants in Mexico due to its high toxicity and persistence in the environment. San Luis Potosi was considered among the 18 states that have problems of heavy metal pollution in abandoned sites [1]. Furthermore, in the Huasteca determined dissolved lead concentrations in Clear Rivers, and Axtla Amajac higher than recommended by the Mexican Official Norm 127-SSA1-1994 relating to water intended for human consumption have been. Based on the foregoing, various technologies have been implemented to remedy sites polluted by heavy metals. Phytoremediation is considered a low-cost technology, in which plants are used to remove or stabilize pollutants in the environment. For phytoremediation processes is important to use plants that have high growth rates, high biomass production, tolerance to adverse conditions such as pH, salinity, composition and water content [2]. Typha latifolia is a plant that meets the requirements to be used in phytoremediation. Methodology Therefore, small plants of a non-contaminated site were collected; washed with tap water followed by deionized water and finally rinsed by immersion in 0.01 M EDTA to remove any metals adsorbed onto the root. Then, the seedlings were placed in solutions of lead and cadmium, for 10 days. To do this three solutions of about 600 to 1500 mL were prepared; T. latifolia and P. stratiotes, respectively. A control (distilled water) was used for both plant species, in the case of Pb concentrations of 5, 10 and 15 ppm were used; Cd 20, 40 and 85 ppm. All solutions were adjusted to a pH of 5.7 and an ionic strength of 0.05 M NaNO3. At the end of the 10 days of exposure, the plants were removed from the solutions, sectioned into root, stem and leaf. They were dried for a period of 48 hours convection oven at 70 ° C and pulverized in an analytical mill. The powdered samples were subjected to acid digestion process with nitric acid and hydrogen peroxide for 5 days at room temperature. Pb (II) and Cd (II) of plant tissues was quantified by atomic absorption spectrophotometry (AAS) method with air-acetylene flame and finally, a statistical analysis of the results with the STATISTICA 8® program.
UNPA MESYRUM 2014
92
Results T. latifolia and water lettuce, accumulated heavy metals in the order of Cd (II)> Pb. Heavy metals were accumulated predominantly in the root. Furthermore, a considerable degree of accumulation in the aerial part of the plants P. stratiotes was observed, suggesting that the plant can translocate the metal directly from the root to the leaf, stem from the lack in their physiological makeup.
Figure 1. Mean concentrations of Pb and Cd in the roots and shoots of T. latifolia exposed to Pb (II) (A, p
<0.05), Cd (II) (B, p <0.05) for 10 daysThe results are presented as the mean ± SD of two independent experiments performed in triplicate
Figure 2. Mean concentrations of Pb and Cd in the roots and shoots of P. stratiotes exposed to Pb (II) (A, p
<0.05), Cd (II) (B, p <0.05) for 10 daysThe results are presented as the mean ± SD of two independent experiments performed in triplicate
UNPA MESYRUM 2014
93
Conclusions It was evident that the accumulation of heavy metals prevalent mainly in the root, being mostly metal cadmium accumulated in both T. latifolia and P. stratiotes; suggesting that both plants have the potential to be used in phytoremediation, considering the exposure periods and phytotoxic parameters and factors that may influence the removal and accumulation of heavy metals. However, there are techniques such as synchrotron light spectroscopy and X-ray spectrum-infrared microscopy used to characterize materials and processes biosorbents for Cr biosorption by plant species such as Typha angustifolia, which could be applied to studies with T. latifolia and Pistia stratiotes to accurately identify the oxidation state and speciation of the compounds removed and accumulated by the plant. References
1. INEGI. (1996). Relación de sitios afectados por disposiciones inadecuadas de residuos peligrosos. México.
2. Vara Prasad, M. N. and De Oliveira Freitas, H.M. (2003). Metal hyperaccumulation in plants - Biodiversity prospecting for phytoremediation technology, Electronic Journal of Biotechnology. 6(3): 285-321.
UNPA MESYRUM 2014
94
Following SDSA1 Crystallization and Its Inhibition by Using Synchrotron Radiation
Omar Mendoza Llerenas,a Juan Alberto Osuna Castro,b Abel Moreno Cárcamo,c Jean Jakoncic,d Nuria Sánchez Puigc*
a Facultad de Química, Universidad de Colima, Coquimatlán, Colima, C.P. 28400, México. b Facultad de Ciencias Biológicas y Agropecuarias, Universidad de Colima, Tecomán, Colima, C.P. 28100,
México c Departamento de Química de Biomacromoléculas, Instituto de Química, UNAM, México, D.F. C.P. 04510,
México. d National Synchrotron Light Source, Brookhaven National Laboratory, X6A Beamline, Upton, N.Y., P.C.
11973, U.S.A. *Email: [email protected]
Keywords: alkylsulfatase, surfactant, X-ray diffraction, synchrotron radiation. Detergents are widely used from house to industry, and its indiscriminated use causes environmental problems. Sodium dodecyl sulfate (SDS) is a surfactant and an essential component of detergent formulations. The degradation of surfactants by microorganism is a well-known strategy, which is applied in sewage treatment plants as well as bioremediation. Pseudomonas ssp. are strains that secrete SDS hydrolases, these enzymes allow bacteria to use surfactants like carbon or sulfur source [1]. In this work, we study an alkylsulfatase (SDSA1) from Pseudomonas sp. that was heterologously expressed in Escherichia coli and purified to homogeneity and crystallized as previously has been reported [2]. The aim of this study was to understand the catalytic mechanism underlying SDSA1 using sodium dodecyl phosphate (SDP) as non-hydrolysable substrate analogue. A couple of methods, co-crystallization and soaking, were performed to obtain crystals of the enzyme-ligand complex. The crystals obtained from the co-crystallization method (Figure 1) were unstable, hence was not possible collect any data. Conversely, the crystals obtained by vapor-diffusion (Figure 2) and soaking them in inhibitor solution (SDP) were diffracted to 2.8 Å resolution and gave complete data sets using a synchrotron X-ray source (Figure 3). We are currently working on the optimization of crystallization conditions to increase resolution and determine structural basis of SDSA1 inhibition by SDP.
Figure 1. Crystals obtained by co-crystallization of SDSA1 and SDP.
UNPA MESYRUM 2014
95
Figure 2. SDSA1 crystals obtained by vapor-diffusion and soaked with SDP solution.
Figure 3. Diffraction image of SDSA1 crystal, soaked with SDP solution. The outer blue circle corresponds to 2.8 Å resolution.
[1] B. Jovcic, V. Venturi, J. Davison, L. Topisirovic, M. Kojic. Journal of Applied Microbiology 109 (2010)
1076-1083. [2] G. Hagelueken, T. M. Adams, L. Wiehlmann, U. Widow, H. Kolmar, B. Tummler, D. W. Heinz, W.
Schubert. 103 (2006) 7631-7636.
UNPA MESYRUM 2014
96
Structural studies of DNA ligase from Thermococcus gammatolerans
Edith Flores Hernándeza, César Cardona Felixa y Enrique Rudiño Piñeraa
aInstituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad #2001, Col. Chamilpa C.P. 62210, Cuernavaca, Morelos
Email: [email protected] Keywords:DNA ligase, Thermococcus gammatolerans, Radioresistance, Hyperthermophile DNA ligases are ubiquitous proteins involved in cellular processes such as replication, repair and recombination of the DNA. These enzymes catalyze the formation of a phosphodiester bond between adjacent5'-phosphate and 3'-hydroxyl termini at single-stranded breaks in double-stranded DNA[1]. There are two classes of DNA ligases, those that utilize NAD+ as a cofactor (such as eubacteria) and those that utilize ATP as a cofactor (such as eukaryotes, virus and archaea). DNA ligases from thermophilic and hyperthermophilic archea have been used as model systems in structural and mechanistic studies of DNA ligation. A number of thermostable DNA ligases from archea have been isolated and functionally characterized and all of them utilized ATP as a cofactor [2]. In this project we works with the radioresistant archaeon, Thermococcus gammatolerans, was recently discovered [3] and belongs to the order the Thermococcales. T. gammatolerans was isolated after an exposure to a gamma irradiation dose of 30 KGy from enriched culture of microorganisms collected at the Guaymas, Sonora basin. As its name suggests, this organism can withstand a dose of 3000 Gy without apparent lethality and an exposure to higher doses only slightly reduces its viability. These data indicate that T. gammatolerans is the most radioresistant archeon isolated thus far, offering the chance to determine how archaeal species recover from extensive DNA damage after exposure to a massive radiation dose [4]. The most widely used technique to elucidate the structure of a protein is X-ray diffraction. Such that 86% of the 3D structures reported in the PDB use this method. Therefore experiments of purification, crystallization and structural determination of T. gammatolerans is an appropriate strategy for atomically describe this enzyme. Because it is known that damage of ionizing radiation on living things affect nucleic acids, the structural analysis of enzymes make the character of this microorganism of higher tolerance to ionizing radiation. This project is framed in the search of DNA repair factors that must exist in T. gammatolerans.Synchrotronlightis usedfor the study ofbiological macromoleculesthroughcrystalsdiffraction technique, using synchrotron light diffraction of the crystals will be faster and thus obtain a data collection in less time; this is possible because the Synchrotron X-ray has higher intensity. DNA ligase from the archeon T. gammatolerans was overexpressed, purified and crystallized. Crystals were obtained using the sitting drop vapor diffusion method employing the mosquito LCP and employing the Wizard Classic crystallization screen series as a precipitant and diffracted X-ray to 10 Å resolution (data not shown). The conditions where crystals grew employing the Wizard Classic crystallization screen series are Wizard I (tube 13: 1260 mM Ammonium sulfate and 100 mM Sodium cacodylate/Hydrochloric acid pH 6.5) (Fig. 1), Wizard II (tube 15: 1260 mM Ammonium sulfate and 100 mM HEPES/Sodium hydroxide pH 7.5) (Fig. 2) and Wizard IV (tube 29: 20% (w/v) PEG 3350, 100 mM Sodium citrate/Citric acid pH 4.0 and 200 mM Sodium citrate tribasic) (Fig. 3). Thecrystal growthwill be optimizedand to obtaina high resolutionin itsdiffraction pattern it’s goingto be solved by molecular-replacement using the 3D structure of Thermococcus sp. 1519 (PDB: 3rr5)[5], because it hashighsequenceidentitywithDNA ligase of T.gammatolerans. 1. Lehman, I.R., DNA ligase: structure, mechanism, and function. Science, 1974. 186(4166): p. 790-7. 2. Petrova, T., et al., ATP-dependent DNA ligase from Thermococcus sp. 1519 displays a new
arrangement of the OB-fold domain. Acta Crystallographica Section F, 2012. 68(12): p. 1440-1447. 3. Jolivet, E., et al., Thermococcus gammatolerans sp. nov., a hyperthermophilic archaeon from a deep-
sea hydrothermal vent that resists ionizing radiation. Int J Syst Evol Microbiol, 2003. 53(Pt 3): p. 847-51.
UNPA MESYRUM 2014
97
4. Tapias, A., C. Leplat, and F. Confalonieri, Recovery of ionizing-radiation damage after high doses of
gamma ray in the hyperthermophilic archaeon Thermococcus gammatolerans. Extremophiles, 2009. 13(2): p. 333-43.
5. Bezsudnova, E.Y., et al., Overexpression, purification and crystallization of a thermostable DNA ligase
from the archaeon Thermococcus sp. 1519. Acta Crystallogr Sect F Struct Biol Cryst Commun, 2009. 65(Pt 4): p. 368-71.
Figure 1. Crystal of recombinant DNA ligase of T. gammatolerans employing the Wizard crystallization screen, employing the Wizard I tube 13.
Figure 2. Crystal of recombinant DNA ligase of T. gammatolerans employing the Wizard crystallization screen, employing the Wizard II tube 15.
Figure 3. Crystal of recombinant DNA ligase of T. gammatolerans employing the Wizard crystallization screen, employing the Wizard IV tube 29.
UNPA MESYRUM 2014
98
Speciation of Fe in Particulate Matter PM10 by X-ray Absorption Spectroscopy (XAS) and Micro X-Ray Fluorescence(µ-XRF) to identify the emitting source in the city of
Leon, Guanajuato.
Gladys Morales-López1,4,, Ma. G. de la Rosa Álvarez 2, Ma. G. García Jiménez1, J.M. Martinez Rosales1, Diana O. Rocha Amador3, Marcos Delgado Ríos4, Hiram Castillo Michel5, Jorge L. Gardea Torresdey6, Gustavo Cruz
Jiménez3.
1Departamento de Química. División de Ciencias Naturales y Exactas. Universidad de Guanajuato. México. 2 División de Ciencias e Ingeniería, Campus León. Universidad de Guanajuato. México.
3 Departamento de Farmacia. División de Ciencias Naturales y Exactas. Universidad de Guanajuato. México. 4 Departamento de Ciencias Químicas y Biológicas de la Universidad de Ciudad Juárez, Chich. México.
5 ESRF (European Synchrotron Radiation Facility), Grenoble, France. 6 Departamento de Química. Universidad de Texas en El Paso, El Paso, Texas.
[email protected] Keywords: PM10, speciation, X-ray Absorption Spectroscopy and Micro X-Ray Fluorescence. Abstract In the state of Guanajuato there is a network of air quality monitoring and one of the pollutants measured is particulate matter PM10. Samples of PM10 filters from the monitoring of the city of Leon, Guanajuato were analyzed. The metal found in higher concentrations in PM10 was Fe. Given the potential impact for human health of Fe present in PM10, its speciation was performed using XAS and µ-XRF. Results obtained by XAS could elucidate that the major oxidation state of iron was Fe (III). Possible species present are (NO3)3, Fe2(SO4)3 and Fe2O3. In order to have security in the speciation of Fe, µ-XRF was used to confirming the results. Fe oxide as magnetite and minor composition FeSO4, Fe, FeS, Fe2 (SO4)3 were found. The results indicate that the emission sources are soil due to wind erosion and dust resuspension due to vehicular traffic. Introduction The mechanisms by which particulate matter (PM) can cause adverse health effects are poorly understood. The importance of speciation of Fe is due to a possible mechanism of health damage due to PM is the generation of hydroxyl radicals (·OH) and other reactive oxygen species (ROS) via transition metals, including Fe (Charrier et al. 2011). The aim of this study was to perform the speciation of Fe present in PM10 by XAS and µ- XRF from the monitoring sites of the city of Leon, Guanajuato. The objective is to obtain information leading to the possible identification of the emitting source. Methodology PM10 sampling were collected in the city of Leon, Gto., in handset Andersen High Volume with fiberglass filters. Dust and soil were collected with a brush and dustpan plastic to avoid contamination. The samples to iron speciation by XAS and µ- XRF requiring minimal treatment, because both techniques are non-destructive, the filters only were cut and mounted on the sample holder. For XAS were used as model compounds FeSO4, Fe(NO3)3, Fe2(SO4)3, Fe2O3 and FeCl3. For XAS analysis used the Beam Line 7-3 of Syncrhrotron Stanford Radiation Laboratories (SSRL). Data analysis was performed with software version 3.2 WinXAS. The µ-XRF mapping of the Fe K-edge was performed with an incident beam 7.2 KeV during continuous operation at the Beam Line ID21 at the European Synchrotron Radiation Facility (ESRF). The data were processed using the software PyMCA. Fe images were obtained by fitting each pixel XRF maps so that the net counts in the images are only the element of interest.
UNPA MESYRUM 2014
99
Results. In the first part of the study, the oxidation state of Fe was obtained by comparison of the XANES spectra of the samples of PM10 with respect to XANES spectra of the model compound. The Figure 1 shows the spectra of samples of PM10 and XANES model compounds and the first derivative spectra. The results indicate that the oxidation state of Fe present in the samples of PM10 is Fe (III), which coincides with the energy value of the peak inflection pre-edge of the first derivative. Linear combination of the XANES spectra of samples of PM10 with XANES spectra of samples of dust and soil was performed, the results indicate a good fit so that it can be suggested Fe present in the PM10, comes from soil and dust generated by resuspension caused by traffic. These results are shown in Table 1. Mapping of samples were performed using the technique of µ-XANES that has the ability to analyze the chemical state of any point of interest in a sample with submicron resolution even of trace elements contained in the parts per million. The results obtained by this method were consistent with those obtained by XAS, since the presence of iron oxide was confirmed as magnetite and minor composition FeSO4, FeS, Fe2(SO4)3 and FeO. In Figure 2 the distribution maps of Fe concentration and µ-XANES spectra with the percentage composition of each compound are shown. Finally, some actions that could be proposed are reforestation, cleaning roads and better control the traffic to improve air quality in Leon city.
Fig. 1 (A) XANES spectra of samples and XANES spectra of model compounds, (B) First derivate spectra of samples and model compounds. The dashed line indicates the energy associated to Fe (III).
Table 1. Linear Combination adjustment percentages of XANES spectra of PM10 and spectra of dust and soil.
Sample
%Cerro de
Jerez´s soil
%Powder
shelter
Sample
%Cerro
de Jerez´s
soil
%Powder
shelter
Sample
%Cerro
de Jerez´s
soil
%Powder
shelter
FC-5927 75.7 24.3 FC-0121 70.4 29.6 FC-0184 100 -
FC-5933 70.4 29.6 FC-0124 58.7 41.3 FC-5901 100 -
FC-0083 92.4 7.6 FC-0178 29.3 70.7 FC-5902 100 -
FC-0117 71.9 28.1 FC-0180 61.6 38.4 FC-5904 97.0 3.0
UNPA MESYRUM 2014
100
Fig. 2 Iron distribution in (A) FC-0083 and (B) FC-0180 PM10 filters (blue- red scale represents iron fluorescence intensity). (C) micro-XANES spectra of selected points in (A) and (B). The (+), (o), (x), (#) symbols correspond to points in (A) and (B), each plot is an average obtained from points labeled with same symbol.
1] Charrier JG, Anastasio C .Impacts of antioxidants on hydroxyl radical production from individual and mixed
transition metals in a surrogate lung fluid. Atmospheric Environ. (2011). 45:7555-7562.
UNPA MESYRUM 2014
101
Determination of exposure to Benzene in child population from Tula de Allende City, Hidalgo, México.
Israel Enciso-Donis a, Gustavo Cruz-Jiménez a, Rogelio Costilla-Salazar b, Diana O. Rocha-Amador a, Fátima del
Carmen Durán-Mendoza a, Ma. Guadalupe de la Rosa-Álvarez c, Nadia A. Pelallo-Martínez d.
a Universidad de Guanajuato, División de Ciencias Naturales y Exactas, Guanajuato, 36050, México b Universidad de Guanajuato, División de Ciencias de la Vida, Irapuato, 36500, México
c Universidad de Guanajuato, División de Ciencias e Ingenierías, León de los Aldama, 37670, México d Universidad del Centro de México, San Luis Potosí, 78250, México
Email: [email protected], [email protected]
Keywords: Benzene, environmental release, exposure, child population, Tula de Allende. Introduction
Benzene is a compound from natural (volcanoes, forest fires, organic matter incomplete combustion) as industrial sources (obtain and process petroleum). Industrial sources are highly relevant because of its wide utility in industry, such as detergent manufacturing, drugs, pesticides, obtaining products as styrene and cyclohexene, as well as gasoline additive [1,2]. The generation and release of benzene to the environment are highly relevant for their wide use as mentioned above, due to adverse effects that them brings, which depend on the levels and time that people are exposed. These adverse effects include headaches, dizziness, confusion, as well as blood disorders, anemia and acute myeloid leukemia. According to the International Agency of Research on Cancer (IARC) this compound is a recognized carcinogen [1,2]. Because of its widespread use and environmental dispersion by different sources, the monitoring or measurement of this compound in the population is of highly important. In the case of Tula de Allende, Hidalgo, children are exposed to pollutants from petrochemical and cement industries, which emit this compound according to Pollutant Emission and Transference Register (RECT 2004-2012 for its acronym in Spanish) [3]. Monitoring is given by measurement of Benzene in breath, blood or urine. The metabolites of benzene can be measure by knowing the metabolic pathway in the body (Figure 1). Some metabolites from Benzene are benzoic acid, trans, trans-muconic acid (AttM) or S-phenylmercapturic acid, which can be measured in blood or urine. In this work we focused in AttM which was determinate in urine samples [1,2]. Results and Discussion
By modifying process used by Ducos et al.[4], we extracted the highest percentage of AttM from a certified standard by at pH 7 with phosphate buffer. Using this procedure, there was an increase of extracted sample from 53% to 85.13%. The validation parameters obtained are showed in Table 1. Thus, 63 samples from children of 2 different elementary schools in Tula de Allende city were analyzed by HPLC-UV (High Performance Liquid Chromatography). The results obtained indicated that 32% of children from Tula showed levels exceeding the permissible limit of the compound (Figure 2). This represents a large number of children affected. It is necessary to make a deeper analysis because the average of AttM in these people are 423.9 µg/g, which are higher than levels seen in studies made in Italy, Thailand and other children from Mexico. It was observed that Tula’s children have problems in their health like blood disorders. In order to analyze Tula´s children urine, we did the analysis in samples from Irapuato´s children as a control population (Table 2), therefore; we could compare the results of both cities. Irapuato’s children samples had values below the limit of detection (LOD), and only three of them showed no peak in the chromatograms.
UNPA MESYRUM 2014
102
Conclusions By modifying the method of extraction and determination proposed by Ducos et al.[4] we could obtain
the higher extraction percentage of AttM by conditioning the sample before it pass through the cartridge, and we obtained values in an acceptable range from certified standards. The HPLC-UV method implemented allows a good determination of AttM in short periods of time as well as analytical parameters. A large percentage of children samples shows AttM superior levels than the NOM-047-SSA1 allows. This is an issue because Mexican regulation is for occupational exposure, so it is necessary to increase the study conducting an exposure assessment in the area.
Figure 1. Metabolic route for benzene. Adapted from Nerbert et al., 2002; Ross 2007[1].
Figure 2. Percentage in infant population with higher and lower levels of AttM established by the NOM-047-SSA1-2011 with permissible limit of 500µg/g of creatinine for occupational exposure[5] from two elementary schools analyzed.}
Table 1. Analytical parameters of the method of analysis by HPLC-UV for AttM in urine.
Parameter AttM
Standards 6 Correlation Coefficient, R2 0.9999 Intercept 11557.25 Slope 271.25 Work Range (µg mL-1) 0.1-5.0 Limit of Detection (µg mL-1) 0.036 Reproducibility (%DSR, n=3, 0.5 µg ml-1 AttM) 0.6 Recovery (Percentage) 85.13 Analysis time (min) 16.0
Table 2. Results in ppm of AttM from Irapuato samples used as control.
OO
OO
OO
OH
OHBenzene
oxideBenzeneoxepin
trans, trans-muconaldehydetrans, trans-muconic acid
CYP2E1ADHALDH
FE/OH-
Benzene
CYP2E1
0
10
20
30
40
50
60
70
Values above NOM-‐047 allows Values lower than NOM-‐047allows
33.3 %
66.6 %
39.1 %
60.9 %
AttM in urine from children
1st Elementary School
2nd Elementary School
UNPA MESYRUM 2014
103
Sample Concentration ppb Sample Concentration
ppb Sample Concentration ppb Sample Concentration
ppb LDS-13 18.00 VTA-22 18.00 VTA-34 18.00 VTA-19 18.00 LDS-25 NP VTA-26 18.00 EF 18.00 LDS-10 18.00 LDS-27 18.00 VTA-28 18.00 LDS-9 18.00 LDS-5 18.00 VTA-3 18.00 VTA-29 NP LDS-20 18.00 LDS-12 18.00 VTA-11 18.00 VTA-32 18.00 LDS-43 NP VTA-54 NP
*NP. The samples in the analysis did not show the peak of the analyte (AttM) References [1] ATSDR, Agency for Toxic Substances and Disease Registry Atlanta, EUA, 2007. [2] IARC, Monographs on the Evaluation of Carcinogenic Risk to Humans International Agency for Research on Cancer: 2012; Vol. 100F-24. [3] SEMARNAT; Secretaría de Medio Ambiente y Recursos Naturales: México, D.F., 2012; Vol. 2014. [4] P. Ducos, R. Gaudin, A. Robert, J. M. Francin, C. Maire, International Archives of Occupational and Environmental Health 62 (1990) 529. [5] SSA, Secretaria de Salud; Diario Oficial de la Federación: México, D.F., 2011; Vol. Primera Sección.
UNPA MESYRUM 2014
104
Morphological Study of Carbon Nanotubes Multi-Walled
Karla J. Tomás-Sebastiána, Bonfilio Javier Arango Perdomoa, María de Jesús Gil-Gallegosa, Yadira Gochi-Poncea
aTechnological Institute of Oaxaca, Oaxaca, 68030, Mexico
Email: [email protected]
Keywords: carbon nanotubes, spray pyrolysis, synchrotron, multi-walled, morphology, CNTs The apparition and study of nanostructures proved to be of great interest since the early 90, because they contained a specific shape that differs from the common materials and have found applications in different areas of technological advances, biomedical and materials science. The extremely small size of the nanotubes lead them to have properties that have no other known materials. The most studied nanomaterials are carbon nanotubes (CNTs), because their physical properties have been the subject of several studies and also have various applications in different areas such as electronics, physics and biology [2], are used in specific applications depending of their morphology and structure which directly affect their final properties [3]. Since the discovery of carbon nanotubes, scientists found ways to produce them in the laboratory. Since then it has advanced in the different synthesis methods, as well as methods of characterization, purification and separation. At the present time there are different methods of synthesis of carbon nanotubes, each method with different characteristics, the most used are: arc discharge, laser ablation, chemical vapour deposition (CVD). In this paper the method used is spray pyrolysis for the synthesis of carbon nanotubes, the Technological Institute of Oaxaca has the necessary equipment to perform such synthesis, also, previous investigation in the Technological Institute of Oaxaca give satisfactory results in obtaining nanotubes. The spray pyrolysis method has attracted the attention of the scientific community because nanotubes are obtained with a high degree of purity and quality, also is efficient, economical and is one of the most suitable techniques for the control of morphology and the chemical composition of the particles for obtaining carbon nanotubes [1]. The objective of this investigation was to obtain carbon nanotubes multi-walled linear type and spiral type. The spray pyrolysis method consists in spraying a solution of the hydrocarbon precursor/catalyst into a quartz tube located inside a tube furnace with flowing argon as the carrier gas (figure 1). Sample flow of hydrocarbon precursor/catalyst and the catalyst concentration is constant. The synthesis temperature varies in a range from 700 to 1000 ° C. The layer of carbon nanotubes multi-walled formed on the inner surface of the quartz tube is mechanically removed for characterization. Carbon nanotubes obtained in this investigation are proposed to be applied chemically and electrically as electrocatalytic fuel cell supports and for solar cell electrodes, to be part of hybrid materials such as zeolites-carbon systems and biochemically for the combination of carbon nanotubes with proteins. The synthesis of carbon nanotubes by spray pyrolysis method is satisfactory, Because we obtained the two morphologies initially proposed, carbon nanotubes multi-walled linear type and spiral type (figures 2 and 3), which have different characteristics such as diameter, length and properties, these morphologies were obtained by different changes of variables during synthesis. In Figure 2 is observed by transmission electron microscopes (TEM) the presence of carbon nanotubes of spiral type, Figure 3 shows a set of nanotubes with formation of the linear type and finally Figure 4shows Raman analysis which provides a well defined spectrum, where there are a number of regions which identify the carbon nanotubes. The study of these nanomaterials requires the use of specialized characterization techniques for determining their properties,with synchrotron radiation we primarily intend adequate characterization of nanostructured systemsand determination of its distinctive and fundamental properties, also to analyze the order of nanostructured arrangements on a macroscopic scale, so, constitutes an excellent complement to techniques as transmission electron microscopes (TEM) or scanning electron microscopy (SEM). The results obtained in this investigation are comparative with previous studies.
UNPA MESYRUM 2014
105
Figure 1. Diagram of the equipment used for the synthesis Figure 2. TEMmicrography of carbon nanotubes of CNTs by the spray pyrolysis method. spiral type.
Figure 3. TEM micrographyof carbon nanotubes Figure 4.Ramanimage of carbon nanotubes multi-walled linear type. linear type and spiral type [1] Aguilar-Elguezabal E., W. Antunez, Alonso G., Paraguay F., Espinosa F., Miki Yoshida M., “Study of
carbon nanotubes by spray pyrolisys and model of growth” CIMAV Diamond and Related Materials, 2005. [2] Guang-Xin Chen, Hun-Sik Kim, Byung Huyn Park and Jin-San Yoom, (May. 2006) “Multi-walled carbon
nanotubes reinforced nylon 6 composites”, polymer, vol. 47, 4760-4767. [3] Zhang M., Li J., (2009), Carbon Nanotubes in Different Shapes, Materials Today, Vol. 12, pp. 6-18.
NTC tipo lineal NTC tipo espiral
UNPA MESYRUM 2014
106
Crystallization of catalase-peroxidase from Neurospora crassa
Lizbeth Garcíaa, Vanessa Vega García b, Adelaida Díaz a, Enrique Rudiño-Piñera a y Wilhelm Hansberg b a Instituto de Biotecnología, UNAM, Cuernavaca, 62250, México
b Instituto de Fisiología Celular, UNAM, México D. F., 04510, México Email: [email protected]
Keywords: Catalase-peroxidase, Crystals, Neurospora crassa, Synchrotron Fungi are organisms whose development present alternative pathways for propagation and reproduction. Most of them involve cell differentiation processes culminating in the production of sexual or asexual spores. In Neurospora crassa, cell differentiation is a response to oxidative stress and thus antioxidant enzymes are critical for development [1, 2]. Several enzymes are capable of degrading hydrogen peroxide: peroxidases, catalases and peroxiredoxins. There are three main groups of enzymes with catalase activity: i) monofunctional catalases, ii) Mn-catalases and iii) catalase-peroxidases (CPs). CPs are dimeric enzymes with a heme group per subunit, are bifunctional, having catalase and peroxidase activity, and are present mainly in bacteria and fungi [2]. CPs present a covalent adduct between a tyrosine, a tryptophan and a methionine, and a mobile arginine at their active center [2, 3]. There are several CP biochemical studies in the literature, however its action mechanism is still under investigation. To date the CP crystallographic structure of two bacteria, one archaeon and one fungus have been determined [4]. To understand the structure and function of the catalase-peroxidase, the gene of catalase-peroxidase (CAT-2) of N. crassa was cloned in pTYB1 vector and the enzyme was expressed in Escherichia coli. The enzyme was purified by affinity chromatography and an anion exchange column. Crystallization trials were made with the purified protein (Figure 1) using the batch method and hanging drop system and the Mosquito LCP crystallization robot. Crystals of catalase-peroxidase (Figure 2) were obtained using the hanging drop method. One crystal was frozen and diffracted in one of the lines of Brookhaven Synchrotron. Crystal optimization is underway. MESYRUM 2014 [1] C. L. Peraza Reyes. Caracterización genética y enzimática de una Catalasa-peroxidasa de Neurospora crassa. Tesis de Doctorado. Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 2005, 115 pp. [2] V. Vega García. En busca de la función de la Catalasa-peroxidasa de Neurospora crassa. Tesis de Maestría. Facultad de Química. Universidad Nacional Autónoma de México, 2011, 75 pp. [3] M. Zámócki. et al. JBC. 287 (2012) 32254-32262. [4] A. Díaz, P.C. Loewen, I. Fita, X. Carpena. ABB. 525 (2012) 102-110.
UNPA MESYRUM 2014
107
Figure 1. CAT-2 purification. SDS-PAGE 10% stained with Brilliant Blue Coomassie
Figure 2. Catalase-peroxidase crystals.
UNPA MESYRUM 2014
108
reSingle photoionization of aluminium like P2+
Lorenzo Hernández a, Aaron Covington b, Edgar Hernández ad, Armando Antillon a , Alejandro Morales a , Kiattichart Chartkunchand b , Alejandro Aguilar c and Guillermo Hinojosa a . a Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México,
A. P. 48-3, Cuernavaca 62251, México. b Physics Department, University of Nevada, Reno NV 89557-0220.
c The Advanced Light Source, Lawrence Berkeley National Laboratory, CA 94720, USA.
d Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Cuernavaca 62210, Mexico Email: [email protected]
Keywords: Photoionization, phosphorus. The photoionization of phosphorus is important to the search of life in the Universe, because light emitted by stars is absorbed by ions in the stellar medium. In this work, we present high-resolution measurements for the single photoionization of P2+ cross sections. The only source for photoionization cross sections and spectra information for these ions were discharge spectra and theoretical models for isoelectronic systems. This results can assist abundance determinations of space phosphorus. Understanding the observed abundances of phosphorus has been an important question; Caau and collaborators [1] proposed the possibility that phosphorus could be formed in late stages of stars. Later, Bon-chul et al. [2] found evidence of phosphorus in supernovae by measuring the infrared spectra in the remanents of Cassiopea A. In addition, extragalactic phosphorus has been observed in the solar photosphere by Ca au et al. [3], in solar twins by Melendez et al. [4] EXPERIMENT The phosphorus ion targets were selected by a mass-to-charge analyzer ion beams that interacted with a monochromatic photon beam from beamline 10.0.1.2 in the Advanced Light Source synchrotron at the Lawrence Berkeley National Laboratory. This was achieved by using the merged-beams technique, that consists in overlapping two beams over a common collinear path. In this case, a photon beam was merged with an ion beam of either P2+ (that here on will be called parent ion beams). As a result of the interaction of both beams, the parent ion beam may ionize again, forming ions (photoions) with a higher charge. The method has been described in detail in previous measurements of photoionization cross section for Ne+ [5]. RESULTS AND DISCUSSION The resulting spectra for the simple photoionization of P2+ is presented as a function of the photon energy in the Figure 1. This spectra can be interpreted as absorption spectra where the final states correspond to product P3+. This spectrum is normalized to the absolute cross section measurements (circles), tabulated in the table 1.
Photoionization process of Figure 1 is described by the following process ,32 +−+ +→+ PePγ where γ is the absorbed photon. The spectra consist of a direct photoionization cross section with superimposed resonant structure. The presence of resonant peaks below the ionization limit, indicates the contribution to the cross section of metastable electronically excited states in the parent ion beams. It was possible to assign most of the resonant structure to Rydberg series which energy is given by:
( )2
2
µ−−=nRzLEn
1 where En are the resonant energies, L is the ionization limit dened as the binding energy of the ground state, or equivalently, as the term energy of an n = 1 state, z is the charge state of ion core, in this case 3, R = 13.606 eV, n is the principal quantum number and µ is the quantum defect. In this case the identified initial states were (3s23p)2PJ J = 1/2, 3/2 doublet converging to final (3s3p)3PJ J = 0, 1 states of P3+. The most prominent series for
UNPA MESYRUM 2014
109
this ion was (3s23p)2P3/2 → (3s3p)3P0 identified as series number III in Fig. 1 and it was possible to derive some of its resonant energies (see Table 2 and 3). The most prominent peak of this particular spectrum remains unassigned. Given the relevance in fundamental physics and in applied plasma, the present data remain to be better understood under the scope of theoretical calculations.
Figure 1: Single photoionization cross section of P2+ measured with a nominal photon energy resolution of 35 meV. Data are small black dots joined by a straight line. The spectrum is normalized to the absolute cross section measurements (open circles) given in Table 1. The position of the resonant energies En are indicated by vertical lines grouped with inclined lines according to the series they assigned to. The limits of each series are indicated by vertical dash or solid lines at the end of the corresponding line group. Initial values of the principal quantum number n of each series are shown close to its corresponding group. The ionization energy is indicated with a solid vertical line marked with a letter T. Resonant energies En and quantum defects are tabulated in Table 2 and 3.
Table 2 Table 3
Table 1
UNPA MESYRUM 2014
110
[1] E. Caau, P. Bonifacio, R. Faraggiana, and M. Seffen. The galactic evolution of phosphorus. Astronomy and Astrophysics, 532 (2011) 1-6. [2] Bon-Chul Koo, Yong-Hyun Lee, Dae-Sik Moon, Sung-Chul Yoon, and John C. Raymond. Phosphorus in the young supernova remnant cassiopeia a. Science, 342 (2013) 1346-1348. [3] E. Caau, M. Steen, L. Sbordone, H. G. Ludwig, and P. Bonifacio. The solar photospheric abundance of phosphorus: results from CO5BOLD 3D model atmospheres. Astronomy and Astrophysics, 473 (2007) L9. [4] J. Melendez, M. Asplund, B. Gustafsson, and D. Yong. The peculiar solar composition and its possible relation to planet formation. The Astrophysical Journal, 704 (2009) L66L70. [5] Covington, A. M. Aguilar, A. Covington I. R., M. F. Gharaibeh, Hinojosa G., Shirley C. A., Phaneuf R. A.,
Alvarez I., Cisneros C., Dominguez-Lopez I., Sant'Anna M. M., Schlachter A. S., McLaughlin B. M., and Dalgarno A. Photoionization of Ne+ using synchrotron radiation. Phys. Rev. A, 66 (2002) 062710.
UNPA MESYRUM 2014
111
Process to Obtain Foams of A356 Aluminum Alloy using Thermal Threated TiH2 as Foaming Agent
Manuel I. Romero-Romero a, Carlos Domínguez-Ríos a, Alfredo Aguilar-Elguezabal a*, Roal Torres-Sánchez a
a Centro de Investigación en Materiales Avanzados, S.C., Chihuahua, C.P. 31109, México
*Corresponding author: [email protected]
Keywords: aluminum foam, titanium hydride, thermal treatment, pore structure, synchrotron Aluminum foams are lightweight materials composed of a gas dispersed in a metal matrix, which possess a unique combination of physical and mechanical properties. The Figure 1 shows aluminum foam produced by CYMAT [1]. Interest on metallic foam are growing due to its use as new engineering material, which are under intensive research worldwide to discover improvements in fabrication processes in order to obtain the highest quality foams. The porosity open or closed of foams allows them to be employed in structural applications with excellent relationship stiffness-to-weight, efficiency in energy absorption, thermal and acoustic control, and other applications more specialized [2]. In the Figure 2 can be seen a foam with open and close porosity [3]. The development of these materials has growth to large extent in countries such as USA, Canada, Germany and Japan. Among the routes reported for the production of metal foams, the methods of melting route and powder metallurgy are the most used [4]. Aluminum foams of closed pore are produced by the direct injection of gas in the molten metal or by using a foaming agent. Foam of this type, can be obtained with the process of CYMAT (Figure 3), which consists of gas injected directly in the molten metal [5]. In other processes as Alporas and Foamtech the foaming agent (TiH2) is mixed into the liquid aluminum, and the foams are produced due to the decomposition of the TiH2. The Alporas process can be seen in Figure 4 [6]. In the other hand, techniques of powder metallurgy (Alulight and Foaminal processes), consist of a mixture of compacted powders of aluminum alloy and foaming agent (TiH2) are heated to promote the decomposition the TiH2 for foaming the metal. Figure 5 shows the Alulight process [7]. The quality of aluminum foams based on getting a uniform distribution of gas into the molten metal to get an homogeneous pore structure. The problem to produce highest quality foams is the premature reaction of blowing agent or the distribution of bubbles into the molten aluminum. The process of CYMAT can inject the gas directly into the molten metal but once inside can’t control the dispersion of the gas. The other processes can’t avoid totally the premature reaction of foaming agent due to the decomposition temperature of TiH2 is below the aluminum melting point. A solution is to apply a thermal pre-treatment on foaming agent to retard its decomposition to create a surface oxide layer with the purpose to increase the blowing agent temperature decomposition, reducing by this way the difference between decomposition temperature of TiH2 and the temperature at which Al-Si melts. The oxide layer retards the gas (H) release, allowing getting the necessary time to mix and distribute TiH2 into liquid metal and thus obtain foams with cellular structure more homogeneous. The objective is develop a lab level process to obtain foams of A356 aluminum alloy, based on melting route, using titanium hydride thermal threated as foaming agent. The proposed process can be seen in Figure 6.
UNPA MESYRUM 2014
112
Potential use of synchrotron techniques: Analyze the decomposition during constant heating of as-received and pre-oxidized titanium hydride (TiH2) powder in flowing and resting Ar can be studied in-situ by synchrotron X-ray diffraction to obtain information about the structure of the oxide layer covering the hydride particles to find the suitable thermal treated foaming agent. Qualitative and quantitative analysis of the pore structure of aluminum foam can be realized by synchrotron X-ray microtomography, i.e., to confirm an homogeneous pore structure by measuring the pore size distribution, wall thickness, and in situ compression damage studies of cellular structure.
Figure 1. Aluminum foam produced by CYMAT [1].
Figure 2. a) Aluminum foam of closed porosity, b) Aluminum foam of open porosity made on plaster mold by infiltration of molten aluminum into polymeric foam [3].
Figure 3. The Stabilized Aluminum Foam horizontal continuous casting system [5].
Figure 4. The Alporas fabrication process [6].
Figure 6. The process to obtain foam of A356 aluminum alloy.
UNPA MESYRUM 2014
113
Figure 5. Fabrication process of aluminum foam parts by Alulight route. [7].
References [1] CYMAT. Available in: http://www.cymat.com/. Accessed the December 12th of 2013. [2] M. Ashby (Ed.), Evans, Metal Foams: a design guide, Butterworth-Heinemann, Boston, 2000. [3] J.A. Gutiérrez-Vázquez, J. Oñoro. Revista de Metalurgia 44(2008) 457-476. [4] J. Banhart, Progress in Materials Science 46(2001) 559-632. [5] Alusion. Technical manual for CYMAT SmartMetal. pp. 1-1, 3-1, 3-2, 3-3. Available in: http://www.alusion.com/download/CymatTechnicalManualNov2009.pdf. Accessed the December 15th of 2013. [6] T. Miyoshi, M. Itoh, S. Akiyama, A. Kitahar. Advanced Engineering Materials 2(2000):179-183. [7] ISOTECH, Inc. Characteristics of Closed Cell Aluminum Foams. pp. 2, 3, 24. Available in: http://catalog.isotechinc.com/Asset/foamed-aluminium.pdf. Accessed the November 15th of 2013.
UNPA MESYRUM 2014
114
Industrial upgrading of Ultrasonic Spray Pyrolysis Technique applied on handicrafts of black clay.
Martha P. García-Ramírez a, Rafael Martínez-Martínez b, Guillermo Juárez-López c, Evaristo I. Velázquez-Cruz
d, Julián J. Carmona-Rodríguez b, Ciro Falcony-Guajardo e.
a Posgrado Tecnología Avanzada de Manufactura
b Instituto de Física y Matemáticas c Centro de Estudios de Nuevos Materiales
d Instituto de Agroindustrias Universidad Tecnológica de la Mixteca. Carretera a Acatlima Km 2.5, C.P 69000.
Huajuapan de León, Oax. México. e CINVESTAV-IPN-DF
Email: [email protected] ABSTRACT
Keywords: Photoluminescent, coatings, handicrafts, black clay The industrial upgrading is an enhancer for regional development, for this reason in this work is presented as goal, to achieve upgrading Ultrasonic Spray Pyrolysis Technique [1], to deposit photoluminescent coatings on black clay handicrafts [2]. These handicrafts are the effort that reflects the development of the community of San Bartolo Coyotepec, Oaxaca. To achieve this, an exhaustive study of the main parameters involved in the process is done, achieving performing coatings on pieces black clay by volume. The main evaluated parameters were: rate of flow the precursor solution, molarity, distance from the nozzle to the surface of the handicrafts, nebulizers operating in parallel, adaptation of a furnace Skutt Automatic Kilm, Portland Oregon 97206 and carrier gas. Preliminary results are presented on the surfaces of handicrafts black clay, with coatings of Al2O3:Ce3+ and Al2O3:Tb3+. The characterization was by means XDR, EDS, SEM and photoluminescence measurements [3]. Using Al2O3 as host materials and doped with rare earth, emissions characteristics are obtained blue and green, respectively [4]. In order to know the chemical composition of the material used as substrate for the deposition of films, it analyzes the clay before and after it has been treated by the thermal process for obtaining black clay. Table 1, shows the results analyzed by EDS. Furthermore, the pattern of X-ray diffraction shows in Figure 1, corresponds to a sample of clay without thermal treatment film but during the thermal process of the clay (above 800 °C) which was treated, observing three crystalline phases well-defined, corresponding to quartz (q), calcite (c) and albite (a). The thin films of Al2O3:Ce3+ deposited on substrates of black clay show emission luminescent color blue under the excitation of ultraviolet. The diffractograms of the films of Al2O3:Ce3+ showed no well-defined phase; all films studied exhibited a broad band with no indication of crystallinity, typical of amorphous materials, such evidence is shown in Figure 2. The effect of the film luminescent Al2O3:Ce3+ deposited on substrates of black clay, shown in Figure 3. The Figure 4 shows the emission spectrum for different concentrations that were prepared the films of Al2O3:Tb3+. Therefore Figure 5 shows the photoluminescence emission in green and blue colors deposited on handicrafts black clay and Figure 6 show handicrafts black clay without photoluminescent coating. [1]R. Martínez-Martínez, M. García-Hipólito, L. Huerta, J. Rickards, U. Caldiño, C. Falcony. Thin Solid Films 515(2006) 607-610. [2]G. Juárez-López, R. Martínez-Martínez, E. Yescas-Mendoza, I.R. Vásquez-Báez, U. Caldiño and C. Falcony.
Photoluminescent films deposited by spray pyrolysis ultrasonic technique of Al2O3:Ce3+, Tb3+ and Ce-Mn on substrates Black clay. Proceeding of the 2nd LACCOTAM2012, ISBN 978-980-7541-00-8. Caracas, Venezuela.
UNPA MESYRUM 2014
115
[3]G. Juárez L., R. Martínez M., A. Aguirre, E, Yescas M., U. Caldiño, C. Falcony. Fotoluminiscencia en
películas de Al2O3:Tb3+ depositadas en substrates de barro negro. 13° Foro Estatal de Investigación e Innovación 2011. ISBN 978-607-7849-19-3.
[4]R. Martínez-Martínez, M. García-Hipólito, F. Ramos-Brito, J.L. Hernández-Pozos, U. Caldiño, C. Falcony, J. Phys. Condens. Matter 17 (2005) 3647.
Table 1. Chemical composition of clay, substrates black clay, luminescent films of Al2O3: Ce3+,
Al2O3: Tb3+, Al2O3: Ce3+: Mn2+ obtained by EDS.
clay Black clay Film Ce3+ Film Tb3+ Element %Peso Formula
C K 12.59 21.48 3.51 3.51 C O K 45.98 39.64 37.07 37.07 O Na K 0.18 0.32 ------ ------ Na Mg K 0.59 0.62 0.75 0.75 Mg Al K 5.41 7.66 24.25 24.25 Al Si K 12.63 18.43 3.83 3.83 Si Cl K ------ ------ 7.21 7.21 Cl K K 1.64 1.97 0.64 0.64 K Ca K 17.18 5.21 1.05 1.05 Ca Ti K ------ 0.37 ------ ------ Ti Fe K 3.80 4.30 14.96 6.73 Fe Ce L ------ ------ 6.73 ------ Ce Tb L ------ ------ ------ 14.96 Tb Total 100.00 100.00 100.00 100.00
20 30 40 50 60 70 80
qcc
ccc
cq
q
Intens
ity (a. u
.)
2 T heta (deg rees )
qqqq
q
q -‐ qua rtzc -‐ ca lc itea -‐ a lbite
c
a
Figure 1. Pattern X-‐ray diffraction for a clay sample.
250 300 350 400 450 500 550 600
5d 4f
Inte
nsid
ad lu
min
isce
nte
(u.a
.)
Wavelength (nm)
Al2O3:Ce3+
(15%)
Al2O3:Ce3+
(13%)
Al2O3:Ce3+
(11%)
Al2O3:Ce3+
(7%)
Al2O3:Ce3+
(5%)
Al2O3:Ce3+
(3%)
Al2O3:Ce3+
(1%)
Figure 2. Pattern X-‐ray diffraction in Al2O3: Ce3+ films.
Figure 3. Emission spectrum corresponding to the different concentrations of Ce3+ in films
Al2O3:Ce3+.
300 350 400 450 500 550 600 650 700 750 800 850
7F 3
7F 4
7F 5
5D 4
5D 4
5D 4
7F 6
Ligh
t Intens
ity (arb
. units)
Waveleng th (nm)
A l2O
3: T b3+(1% )
A l2O
3: T b3+(3% )
A l2O
3: T b3+(5% )
A l2O
3: T b3+(7% )
A l2O
3: T b3+(9% )
A l2O
3: T b3+(11% )
A l2O
3: T b3+(13% )
A l2O
3: T b3+(15% )
5D 4
Figure 4. Emission spectrum corresponding to the different concentrations of Tb3+ in films
Al2O3:Tb3+.
UNPA MESYRUM 2014
116
UNPA MESYRUM 2014
117
Mechanochemical synthesis and characterization of ReC and ReB2
Mizraim G. Granados-Fitcha,*, Juan M. Quintana-Melgozab, Erick A. Juarez-Arellanoc, Miguel Ávalos-Borjaa,d
aInstituto Potosino de Investigación Científica y Tecnológica, División de Materiales Avanzados, San Luis
Potosí, C.P. 78216, México. bFacultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, campus Tijuana,
Tijuana, C.P. 22390, México. cInstituto de Química Aplicada, Universidad del Papaloapan, campus Tuxtepec, Tuxtepec, C.P. 68301, México.
dCentro de Nanociencias y Nanotecnología, UNAM, Ensenada, C.P. 22800, México. Email: [email protected]
Keywords: Mechanochemical, rhenium, carbide, diboride, synthesis, characterization Carbides and borides of transition metals are very interesting compounds with physical properties such as high melting point, low compressibility, high strength and hardness, low density, excellent electrical conductivity, which make them potential industrial application materials [1-3]. The first synthesis of rhenium carbide (ReC) was reported in 1971 by Popova S. et al. [4], which is achieved from metallic Re and C-graphite at 6 GPa and 800 °C. The rhenium diboride (ReB2) was reported in 1962 by La Placa et al. [5], their synthesis consisted of heating Re/B at ratio 1:2 into a silica tube at 1200 ºC by 12 hours. The ReC phase has never been synthesized at 25 °C and 1 atm of pressure, the common methods use high pressure and high temperature, on the other hand, Orlovskaya N. et al. [6] reported in 2011 the synthesis mechanochemical of ReB2 powders, obtained at 30 hours of reaction using a SPEX 8000 mixer bowl mill and tungsten carbide balls. In this work, we report the ReC synthesis at 25 °C and 1 atm and synthesis of ReB2 by mechanical milling method during 10.6 hours. The analysis by X-ray diffraction shows the phase obtaining rhenium carbide (ReC) with a substantial contamination from the tungsten carbide bowl and griding media, see Figure 1; instead the analysis of the material rhenium diboride (ReB2) shows the synthesis of a single-phase materials. Analysis of scanning electron microscopy shows that the characteristic morphology ReC particle clusters faceted hexagonal faces, see Figure 2 and ReB2 octahedral clusters of microparticles, see Figure 3. Thermogravimetric analysis of the ReC in the range from 50 ºC to 800 ºC shows that loses up to 3.6 % of the initial mass, see Figure 4 while ReB2 loses 7.4 % of its initial mass up to 379 ºC. The infrared spectroscopy analysis of the ReC and ReB2 materials shows bands associated with the surface oxidation of the microparticles by contact whith ambient oxygen and water. Finally, the BET surface area analysis of the material shows low surface areas: 2.0087 m2g-1 for ReC and 0.7295 m2g-1 for ReB2. Acknowledgments. The authors acknowledge through a scholarship support from CONACYT to MGGF and the funding of this research through grant CB-2010-01-151551. Likewise also to IPICYT, UNPA, UABC for providing laboratory support in synthesis and characterization of materials. We are very grateful to Dra. Gladis Judith Labrada Delgado, M. C. Ana Iris Peña Maldonado and M. C. Dulce Partida Gutiérrez. References [1] A. Friedrich, B. Winkler, E. A. Juarez-Arellano, L. Bayarjargal. Materials 4 (2001)1648-1692. [2] B. Ganem, J. Osby. Chemical Reviews 86 (1986) 763-780. [3] T. Ohji, M. Singh, Advanced processing and manufacturing technologies for structural and multifunctional
materials III, John Wiley, USA, 2010. [4] S. Popova, L. Boiko. High Temperatures-High Pressures 3 (1971) 237-238. [5] S. La Placa, B. Post. Acta Crystallographica 15 (1962) 97-99. [6] N. Orlovskaya, Z. Xie, M. Klimov, H. Heinrich, D. Restrepo, R. Blair, C. Suryanarayana, Journal of
Materials Research 26 (2011) 2772-2779.
UNPA MESYRUM 2014
118
Figure 1. XRD patterns of the material obtained at 40, 80 and 640 minutes of milling.
Figure 2. Cluster and particles of the material ReC. Both secondary electron images (a, b).
Figure 3. Morphology of clusters ReB2. Secondary electron image (a) and backscattered electron image (b).
Figure 4. ReC thermogram from 50 ºC to 800 ºC.
20 30 40 50 60 70 80
Intensity (a.u.)
2T heta (deg re)
850min 800min 640min 80min 40min
100 200 300 400 500 600 700 800
11.0
11.1
11.2
11.3
11.4
Mas
s (m
g)
T emperature (ºC )
B
UNPA MESYRUM 2014
119
SIZE CONTROL IN THE SINTHESYS OF MAGNETIC NANOPARTICLES FOR BIOMEDICAL APPLICATIONS
José de Jesus Ibarra-Sanchez c, Juan C. Martínez-Espinosa b, Pablo Villegas Molina b, María L.Vera-Yepez b,
Teodoro Cordova-Fraga a, María G. De la Rosa-Alvarez a
a DCI, Universidad de Guanajuato, Campus León, León, Guanajuato, 37150, Mexico. b UPIIG, Instituto Politécnico Nacional, Silao de la Victoria, Guanajuato, Mexico.
c Universidad de la Salle Bajío, León, Guanajuato, 37150, Mexico. Email: [email protected]
Keywords: Magnetic nanoparticles, thermal decomposition, size control, chemical kinetics. Abstract: The use of metallic nanomaterials for various pharmaceutical and biomedical applications is increasing worldwide. In this research, Fe3O4 nanoparticles (NPs) 10 to 15 nm in size were synthesized by thermal decomposition of iron acetylacetonate (III) in 1-octadecene in the presence of oleic acid as surfactant and oleylamine and 1,2-Dodecanediol as reducing agents. The morphology and size of the NPs were characterized by Transmission Electron Microscopy (TEM). The presence of magnetite and potential impurities were determined using X-ray diffraction (XRD). Organic capping molecules were characterized through infrared spectroscopy (IR). The saturation magnetization was determined from their hysteresis loop by using a vibrating sample magnetometer (VSM). The magnetic susceptibility of the colloidal suspension help in determining the concentration of magnetite. With this information, the reaction kinetics was obtained in situ. The NPs showed to have a very low polydispersity (0.06) and a magnetization saturation of 74 emu/g, which is very similar to the bulk material (84 emu/g), furthermore, the NPs hysteresis loop showed a superparamagnetic behavior, Fe3O4 NPs crystallographic nature was verified through the XRD pattern, which showed an inverse spinel structure. IR spectra displayed the typical vibrations of Fe-O as reported by Gillot et al. (1994) (510 cm-1 and 400 cm-1). This provide an indication of a transition of iron atoms in the cubic face-centered structure (Fd3m) in which there is not order in the vacancies. The relationship between magnetic susceptibility and Fe3O4 concentration showed a linear dependence, yielding a correlation factor of 0.99. Finally this correlation was used to determine the kinetics of the reaction, this one was showed sigmoidal behavior which is similar to the autocatalytic reactions. Therefore, the NPs grow followed an Ostwald ripening behavior, and a minimum initial concentration of magnetite in the reaction was required, which was produced by partial reduction of the precursor. Subsequently, the data were fitted to a Boltzmann double function model available in Origin software version 8.0, where the correlation factor obtained was 0.99. In conclusion, these nanoparticles were obtained with high cristallinity and low polydispersity. These particles are potential candidates for biomedical applications. Results: MNPs in all cases was obtained (Table 1), to confirm this was required identify the resulting iron oxide phase. Because in each case the same material is obtained, only one sample was analyzed by XRD. Thus, Figure 1 shows only the spectrum of the synthesized sample at 30 min (S4). Data shows that seven distinct diffraction peaks, and the structure was assigned to magnetite (Fe3O4) (JCPDS no.00-001-1111). By using the Scherrer equation, crystallite size was estimated to be 0.83960 nm. The small deviation present in all cases could be due to defects inherent to the material in its nanocrystalline structure, being the surface the main defect source. In Table 1 showed the particle sizes obtained at different reaction conditions. This table shows that there is a direct relationship between the reaction time and the particle size, and also in all cases was obtained a very low polydispersity, which is observed in the micrographs of the Figure 3, where all MNPs synthesized have a spherical shape. [1] King-Chuen Wu, Ching-Li Tseng, Chi-Chang Wu, Feng-Chen Kao, Yuan-Kun Tu, Edmund C So and Yang-
Kao Wang, Science and Technology of Advanced Materials 14, (2013). [2] Cano M.E., Cordova F.T., Sosa A.M., Bernal A.J., Baffa O, European Journal of Physics 29, (2008). [3] Gupta, A. K., Gupta, M. Biomaterials, 26 (18), (2005). [4] Mürbe, J. Rechtenbach, A. Töpfer, J., Materials Chemistry and Physics, 110 (2-3) (2008).
UNPA MESYRUM 2014
120
Figure 1. XRD pattern of MNPs (sample S4).
Figure 2. Infrared spectra of magnetite powder: (A) S3; (B) S4; (c) S5.
Figure 3. TEM micrographs of magnetite samples: (A) S1; (B) S2; (c) S3; (D) S4; (E) S5; (F) S6.
Table 1. Particle size and polydispersity of the MNPs synthesized at different times. Sample Time (min) DTEM (nm) Polydispersity (σP)
S1 10 5.0 0.03 S2 15 7.5 0.03 S3 20 8.3 0.04 S4 30 10.0 0.02 S5 40 11.0 0.01 S6 50 12.0 0.01
30.158(220)
35.522(311)
43.173(400)
53.563(422)
57.100(511)
62.704(440)
74.188(533)
20 30 40 50 60 70 80 908000
9600
11200
12800
14400
16000
a.u.
2θ (° )
20 30 40 50 60 70 80 90
8000
9600
11200
12800
14400
16000
4000 3600 3200 2800 2400 2000 1600 1200 800 400-‐0.4
-‐0.2
0.0
0.2
0.4
0.6
0.8
Abs
orna
nce (a.u.)
W ave number (cm -‐1)
4000 3600 3200 2800 2400 2000 1600 1200 800 400
-‐0.4
-‐0.2
0.0
0.2
0.4
0.6
0.8
29162849
1428
1071
849
A)
B)
C)
UNPA MESYRUM 2014
121
Influence of the length on the mechanical tension to the fibers properties Agave angustifolia Haw
Rey F. García-Méndeza, b Yadira Gochi-Poncea Froylan Martínez-Suarezc
aInstituto Tecnológico de Oaxaca, Department of Chemical and Biochemical Engineering, Av. Ing. Víctor Bravo
Ahuja 125 esquina Calzada Tecnológico, Oaxaca C. P. 68030, México bInstituto Tecnológico Superior de Teposcolula, Department of Engineering, San Pedro y San Pablo
Teposcolula, Oaxaca C. P. 69500, México cCentro Nacional de Metrología, Department of Materials Metrology, Carretera a Los Cues km 4.5, El Marques,
Querétaro, C. P. 76246
e-mail: [email protected]
Keywords: Agave Fibers, mechanics properties, statistics analysis
In this paper the influence of the length of the mechanical tension of the fibers of Agave angustifolia Haw properties was analyzed. The methodology began with extraction fibers by machining process, then the area of the cross section of each of the fibers was calculated from the average diameter, measurements were performed using a microscope Digital model BW1008 Micro-measure, through a USB interface images in real time on a computer equipment were collected, diameter measurements were carried out with the program Axionvision. Consecutively, four lengths of fiber 10, 20, 30 y 40 mm were evaluated through tension tests under the ASTM C1557 standard, the test speed was 0.2 mm / min. The correlation between the lengths of the tensile strength of agave fibers was determined by Weibull analysis. Scanning electron microscopy (SEM) was used to observe the surface area of the fibers .The results show that the length has no influence on the strength, but if on the deformation and the elasticity modulus (p < 0.05). Based on observations by SEM, the fibers have a heterogeneous structure are composed of microfibres which in turn are composed of helical and jacketed tissue by an even film, both are responsible for confer elasticity and resistance to the fiber, the fibers has defects along their length and area of the cross section.
UNPA MESYRUM 2014
122
Synthesis ofPlatinum Chalcogenides and Cobalt Spinels in Disordered Phaseby the Methods of Chalcogen Dispersion and Mechanic Milling
Salvador Aguilar Hernándeza, E. A. Juárez Arellanob, Marco A. Sánchez Medinaa,Y. Gochi Poncea
aInstituto Tecnológico de Oaxaca,Oaxaca de Juárez, C.P. 68030, Oaxaca. bUniversidad del Papaloapan Campus Tuxtepec, Tuxtepec, C.P. 38301, Oaxaca.
Email: [email protected] Keywords: Fuel cell, Cathode electrocatalyst, Mechanic milling, Dispersion, Chalcogen. In this workthe methods of chalcogen dispersion (CD) and mechanic milling (MM) were applied to synthesize platinum chalcogenides and cobalt spinels in disordered phase respectively, in order to obtain catalytic precursors and generateelectrocatalysts to be appliedin the proton exchange membrane fuel cell (PEMFC). The electrocatalyst in these devices takes an important role, since it promote the proton generation and therefore exist an electron transfer. The oxygen reduction reaction (ORR) is six times slower than hydrogen oxidation reaction (HOR). If the electrocatalyst were more effective, the efficiency of the cell would also enhance. The choice is made to synthesize nanometric metastable materials as electrocatalysts. The most important metals to electrocatalysis are the VIIIB and IB metal groups of the periodic system [1, 2]. The materials synthesize by the chalcogen dispersion method was undertaken with a mixture of ammonium hexacloroplatinate and the chalcogen (sulphur or selenium) into deionized water until get high dispersion; in the stoichiometry, the unique change was the chalcogen molar ratio, the platinum salt ratio was unchanged (Table 1) [3].The chalcogen-platinum salt mixture was carried out by constant shaking during 12 hours; the products were seeped in vacuum using a MILLIPORE device and washed with deionized water, finally the samples were dried at room temperature during 12 hours into a desiccator which were analyzed by thermogravimetric analysis (TGA) to obtain a possible thermal treatment (TT) temperature. Furthermore, the mechanic milling method was applied to synthesize cobalt oxides, specifically cobalt spinels in disordered phase (CoCo2O4). The milling begins with CoCl2·6H2O,hardened steel (HS) was the milling material, the speed 600 rpm and the time was 10 minutes. The products were analyzed by TGA and X-ray diffraction (XRD). The mechanic milling, TGA, XRD and TT analysis took place in the Universidad del PapaloapanCampus Tuxtepec. Pt:S precursors show four main loosing weigh stages and them correspond to physiadsorbed water in the material surface,the ammonium isolation of the molecule and the ammonia and hydrogen obtaining, the separation of the sulfur and its volatilization (Figure 1). Pt:Se materials show significant weight lost, it is similar to platinum-sulphur materials, this behavior does not occur with Pt:S materials (Figure 2). The diffractogram which corresponds to the MM product (Figure 3) shows cobalt spinels formation in disordered phase and it agrees with the results of Lui& Prewitt (1990) in the project of G. García-Pacheco (2007) [4]. They prove nanometric structures existence generated by milling. Recently, cobalt oxides have been proved as cathodic electrocatalystsand it favors the catalytic activity and the oxygen reduction reaction through a four-electron pathway [5, 6]. The TGA results of the 6 Pt:Se catalytic precursors showed similar behavior during the analysis. The thermal stability reached at the range of 325°C-475°C, it was higher than Pt:S precursors. Moreover, the Pt:S catalytic precursors result was not homogeneous, nevertheless the stabilizing temperature range was447°C-457°C. The mechanic milling made the sample became amorphous withHS, in this respect TGA and differential thermic analysis (DTA) were carried out to determinate recrystallization temperatures where the recrystallization range was found (300°C-600°C), likewise a thermal treatment took place with normal conditions atmosphere. The TT at 600°C shows the formation of cobalt spinel in disordered phase.
UNPA MESYRUM 2014
123
XRD of the sample after the thermal treatment Cobalt spinels in disordered phase CoCo2O4 Dihydrate cobalt chloride CoCl2.2H2O
Table 1. Proposed equations to platinum chalcogenides synthesis
Reactions withsulphur
(1) (NH!)!PtCl! + S (NH!)!Pt!S! + 3Cl!
(2) (NH!)!PtCl! + 3S (NH!)!Pt!S!" +
3Cl!
(3) (NH!)!PtCl! + 5S (NH!)!Pt!S!" +
3Cl!
Reactions with selenium
(1) (NH!)!PtCl! + Se (NH!)!Pt!Se! + 3Cl!
(2) (NH!)!PtCl! + 3Se (NH!)!Pt!Se!" + 3Cl!
(3) (NH!)!PtCl! + 5Se (NH!)!Pt!Se!" + 3Cl!
Figure1. TGA of Pt:S precursor with molar ratio1:1, 1:3 and 1:5
Figure 2. TGA of Pt:Se precursor with molar ratio 1:1, 1:3and 1:5
Figure 3. Diffractogram of the cobalt and sulphur sample under MM with HS, 600 rpm and 10 minutes after a second TT at 600°C in normal conditions atmosphere.
UNPA MESYRUM 2014
124
REFERENCES
[1] Y. Feng, A. Gago, L. Timperman, N. Alonso Vante, Chalcogenide metal centers for oxygen reduction reaction: activity and tolerance. ElectrochimicaActa 56(2011) 1009–1022. [2] N. Alonso Vante, Chevrel phases and chalcogenides, John Wiley & Sons Inc., Poitiers 2003, p. 534-543. [3] Y. Gochi Ponce, G. Alonso Nuñez, N. Alonso Vante, Synthesis and electrochemical characterization of a novel platinum chalcogenide electrocatalyst with an enhanced tolerance to methanol in the oxygen reduction reaction. ScienceDirect 8 (2006), 1487–1491. [4] G. García Pacheco,Producción y caracterización de óxidos nanocristalinos de metales de transición,MS thesis, Department of Chemestry, Instituto Politécnico Nacional,2007. [5] F. Sun, G. Zhang, Yi Xu, Z. Chang, P. Wan, Y. Li, X. Sun, Promoted Oxygen Reduction Activity of Ag/Reduced Graphene Oxide by Incorporated CoOx,ElectrochimicaActa 132 (2014) 136–141. [6] X. B. Gong, S. J.You, X. H. Wang, J. N. Zhang, Y. Gan, N. Q. Ren, A novel stainless steel mesh/cobalt oxide hybrid electrode for efficient catalysis of oxygen reduction in a microbial fuel cell. Biosensors and Bielectronics 55 (2013) 237–241.
UNPA MESYRUM 2014
125
Thermal Properties of Polypropylene Composites and CarbonAllotrope J. Avendaño Garcíaa, C. Velasco Santosb, c, A. L. Martínez Hernándezb, c,A. D. Pérez Santiago a,Y. Gochi-Poncea
aInstituto Tecnológico de Oaxaca, División de Estudios de Posgrado e Investigación.. Av. Ing. Víctor Bravo Ahuja #125 esq. Calz. Tecnológico, C.P.68030, Oaxaca, Oax.
bCentro de Física Aplicada y Tecnología Avanzada, UNAM. Boulevard Juriquilla No. 3001, Juriquilla, C.P. 76230, Querétaro, México.
cInstituto Tecnológico de Querétaro, Av. Tecnológico s/n esq. Mariano Escobedo Col. Centro, C.P. 76000, Querétaro, Qro.
e-mail: [email protected]
Keywords:polypropylene; carbon nanotubes; carbon fibers, Since the discovery of carbon nanotubes (CNTs) in 1991 by Iijima [1] and the research of their unique physical properties, including mechanical, thermal, and electrical, many scientists have endeavored to fabricate advanced CNT composite materials that exhibit one or more of these properties [2- 4]. Polyacrylonitrile(PAN)-based carbon fiber (CF) occupies a premier position among high-performance fibers for composites. This was releasedinto the marketsince 1960s (Shindo, 1961). The first decade of its use may be regarded as a period of incubation. During the second and third decades, the CF hada remarkable growth in producing technology, particularly with respect to tensile strength [5]. Polypropylene (PP) is a commodity polymer with a wide range of commercial uses, in a variety of forms, including fibers. Thus, enhancing of PP properties through the dispersal of fillersshould be of significant interest [6] Composite materials appeared due to the necessities of industrial and technological advances, mainly, the requirements of materials with better mechanical properties, for instance the underweight for specific applications, such as aerospace’s and automotive´s. The relationship between mechanical properties and low weight is very important as if the weight reduces and the cost fuel. In this work, the synthesis and characterization of polymer composites were performed. The composites are materials composed by two or more different materials, one of them is the greater material a weight percentage and is called matrix and the second one that has lower percentage is the reinforcement. Polypropylene and two different materials at micro- and nano- scaletwere used as matrix and reinforcement, respectively. Carbon fibers (CF) were used as micro-materials reinforced and multi-walled carbon nanotubes (MWCNT) as nano-materials reinforced. The reinforcement concentrations were 1 and 5% weight of carbon fibers and 0.05, 0.1 and 0.5% weight of carbon nanotubes. The composite was synthesized in a semi-industrial plastic injection machine and carbon materials were chemically untreated samples (reinforcement and matrix). Subsequently, a differential scanning calorimetry (DSC) to the samples was carried out. Figures 1-3 indicate the melting behavior of blends,it suggeststhat the percentage does not affect the melting temperature of the composites.
UNPA MESYRUM 2014
126
-1.5
-1.0
-0.5
0.0
0.5
Hea
t Flo
w (
W/g
)
-50 0 50 100 150 200 250
Temperature (°C)
PP––––––– PP1FC––––––– PP5FC–––––––
Exo Up Universal V4.5A TA Instruments
-1.5
-1.0
-0.5
0.0
0.5
Hea
t Flo
w (
W/g
)
-50 0 50 100 150 200 250
Temperature (°C)
PP––––––– PP0.05NTC––––––– PP0.1NTC––––––– PP0.5NTC–––––––
Exo Up Universal V4.5A TA Instruments
-1.5
-1.0
-0.5
0.0
0.5
Hea
t Flo
w (W
/g)
-50 0 50 100 150 200 250
Temperature (°C)
PP––––––– PP1FC0.05NTC––––––– PP1FC0.1NTC––––––– PP1FC0.5NTC––––––– PP5FC0.05NTC––––––– PP5FC0.1NTC––––––– PP5FC0.5NTC–––––––
Exo Up Universal V4.5A TA Instruments
Figure 1. Thermograms of polypropylene and composites of polypropylene reinforced whit carbon fiber
Figure 2. Thermograms of polypropylene and composites of polypropylene reinforced whit multi walled carbon
nanotubes
Figure 1. Thermograms of polypropylene and composites of polypropylene reinforced whit carbon fiber and multi
walled carbon nanotubes
[1] S.Iijima, Nature, 354, (1991) 56 [2] M.J. Biercuk, M.C. Llaguno, M. Radosvljevic, J.K. Hyun, A.T. Johnson, ApplPhysLett, 80. (2002) 15. [3] Ounaies Z., Park C., Wise K.E., Siochi E.J., Harrison J.S. Compos Sci Technol. 63,(2003); 1637–46.. [4] Weisenberger M.C., Grulke E.A., Jacques D., Rantell T., Andrews R. J Nanosci Nanotech 3 (2003);535-539. [5] Anthony Kelly and Carl Zweben.Comprehensive Composite Materials 1 (2000). 1-33 [6] Moncy V. Jose, Derrick Dean, James Tyner, Gary Price, Elijah Nyairo. Journal of Applied Polymer Science. 103, (2007), 3844-3850
UNPA MESYRUM 2014
127
Evaluation of different culture media to improve the production of parasporal crystals in Bacillus thuringiensis
Alain Cruz-Nolasco1, Rigoberto Martínez-García1, Erick A. Juárez-Arellano2, A. Karin Navarro-Mtz3.
1División de Estudios de Posgrado 2Instituto de Química Aplicada
3Instituto de Biotecnología.
Universidad del Papaloapan, Av. Circuito Central No. 200, Tuxtepec, Oaxaca, México C.P. 68301. [email protected], [email protected], [email protected], [email protected].
Keywords: Bacillus thuringiensis, Parasporal crystal protein, XRD
Introduction. Bacillus thuringiensis is a Gram-positive and spore-forming bacteria and belong to the Bacillus cereus group. This group includes six highly related species: B. cereus, Bacillus anthracis, Bacillus thuringiensis, Bacillus mycoides, Bacillus pseudomycoides and Bacillus weihenstephanensis. The B. thuringiensis species are distinguished from the other Bacillus species by the synthesis of crystal proteins during the sporulation phase, these proteins are named Cry (Soufiane 2008). Some of these protein crystals are toxic for a wide range of insects belonging to Lepidoptera, Coleoptera, Diptera, Hymenoptera and Homoptera orders (Schnepf et al. 1998). Thus, B. thuringiensis has been the most widely used bacterium over the last 50 years for biological control (Siegel 2001). Recently, it has been reported that some Cry proteins are cytotoxic against several vertebrate cells, including human cancer cells. These Cry proteins are named ‘parasporin’ (Mizuki et al. 2000). To study the mechanism of action or the Cry and parasporin is necessary to know the protein structure. For these studies are required large quantities of crystal proteins. Several culture media have been proposed to increase the production of these crystal proteins in Bacillus thuringiensis. In the present study four culture media was used to improve the crystal protein production for Bacillus thuringiensis. Materials and Methods. Four culture media were used in this study (Table 1). The soybean meal for GRM was modificated using a High-Energy ball milling with 20 mm iron balls, 250 ml vial, weight ratio 1:50 sample-balls, 20 min milling time. Three Bacillus thuringiensis strains were used, B. thuringiensis var. kurstaki HD-73, B. thuringiensis var. kurstaki HD-1 and B. thuringiensis var. higo. The cultures conditions were 30°C, 180 rpm for 7 days. At the end of the culture the media was centrifugate at 5500 rpm for 15 min. For B. thuringiensis var. kurstaki HD-73 in Gerry Rowe medium after the centrifugation, the pellet was re-suspended in NaCl (0.85%) and then it was centrifugated again (5000 rpm for 15 min). the supernatant was discarded and the pellet was cold drying at -50°C and -0.05 mBar. The dry pellet was analyzed by XRD using a Bruker D-8 Advance diffractometer (Cu-Kα, 5-50 °, scan step 0.1°, scan time 4s). Results. It is known that Gerry Rowe media show the best production of parasporal crystals for B. thuringiensis. However, culture media ball milled show a better production than conventional Gerry Rowe at standard conditions (Figure 1). The early treatment of the soybean can improve the media conditions to obtain a higher production of crystals in Bacillus thuringiensis. Conclusions. Modified Gerry Rowe culture media shows a significant improvement of parasporal crystals production in Bacillus thuringiensis. XRD is crucial to evaluate the presence of crystalline bodies in samples of Bacillus thuringiensis.
UNPA MESYRUM 2014
128
References. Mizuki, E., Ohba, M., Akao, T., Yamashita, S., Saitoh, H. y Park, Y.S. (2000) Unique activity associated with non-insecticidal Bacillus thuringiensis parasporal inclusions: in vitrocell-killing action on human cancer cells. J Appl Microbiol 86:477–486. Schnepf, E., Crickmore, N., Van Rie, J., Lereclus, D., Baum, J., Feitelson, J., Zeigler, D. y Dean, D. (1998) Bacillus thuringiensis and its pesticidal crystal proteins. Microbiol Mol Biol Rev 6:775–806. Siegel, J.P. (2001) The mammalian safety of Bacillus thuringiensis based insecticides.J Invertebr Pathol 77, 13–21. Soufiane, B. y Cote J. (2008) Discrimination among Bacillus thuringiensis H serotypes, serovars and strains based on 16S rRNA, gyrB and aroE gene sequence analyses. Antonie van Leeuwenhoek. 95:33–45.
Table 1. Composition of the culture media used.
Culture Media Components
Nutritive Broth (NB) Peptone, Meat Extract
Gerry Rowe (GR) Glucose, Peptone and Yeast Extract
Soybean Meal (SM) Glucose, Soybean meal, Yeast Extract and Corn steep solids
Gerry Rowe Modified (GRM) Glucose, Yeast Extract and Soybean Meal
Figure 1. X Ray diffraction pattern of B. thuringiensis cristalline paraesporal inclusion from different culture media. GRM: Gerry Rowe Modified; GR: Gerry Rowe; SM: Soybean Meal; NB: Nutritive Broth; NB*: Nutritive Broth not inoculated. Differences are significant for each media.
UNPA MESYRUM 2014
129
COUNT OF PUBLICATIONS PER YEAR ABOUT THE DIFFERENT BEAMLINES COUNTED BY DIAMOND LIGHT SOURCE (DLS).
Alvaro Bahena Bárcenas
Faculty of Sciences, Universidad Autónoma del Estado de Morelos, Av. Universidad No. 1001, Col. Chamilpa, C. P. 62210, Cuernavaca, Morelos, México.
Correo: [email protected] In the present work is carried out a count per year from 2010 to date of publications of each of the 22 beamlines in operation of Diamond Light Source (DLS). This comparative work is of great importance to see the beamlines with the largest number of publications and use it as a reference in a future in accordance with specific needs in the construction of a Synchrotron in México. Below are graphs different from the year 2010 to 2014 comparing the number of publications per beamline:
Fig. 1: Distribution of the beamlines of DLS.
Fig.2: The I02 line has the highest number of publications in 2010 with a total of 80.
Fig. 3: The I03 line has the highest number of publications in 2011 with a total of 104.
UNPA MESYRUM 2014
130
However, the beamlines I05, I08, I09, I13 and B21 are in optimization mode, while lines B07, I21, I14 and B24 are under construction.
BIBLIOGRAPHY: http://www.diamond.ac.uk/Home.html
Fig. 4: The I04 line has the highest number of publications in 2012 with a total of 92.
Fig. 5: The I02 line has the highest number of publications in 2013 with a total of 112.
Fig. 6: The I03 line has the highest number of publications in 2014 with a total of 54.
UNPA MESYRUM 2014
131
SOLVOTHERMAL SYNTHESIS AND CHARACTERIZATION OF Fe-BTC AND Cu-BTC FOR HYDROGEN STORAGE AND METHANE CAPTURE.
Jade A. Galiciaa, Neil Torres Figueredo c, Erick A. Juárez-Arellano b , E. Reguera-Ruizc , Adela Lemus S.c
a División de estudios de posgrado, Universidad del Papaloapan Campus Tuxtepec. Av. Circuito Central No.200.
Tuxtepec, OAX. C.P 68301. b Instituto de Química Aplicada, Universidad del Papaloapan, Circuito Central No. 20, Col Parque Industrial,
Tuxtepec, Oaxaca. C.P. 38301, México. c Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada-Unidad Legaría, Instituto Politécnico
Nacional, México, D.F.
Email: [email protected] [email protected] Keywords: MOFs, Cu-BTC, Fe-BTC, storage. The need for alternative fuels is greater now than ever. Therefore, natural gas is promising fuel source due to their availability and low contamination factor, which make it a natural choice as a substitute for oil in cars and other mobile applications. However, due to the lack of efficient storage methods it has not been fully implemented in the automotive industry [1]. Advanced porous materials, such as metal-organic frameworks, have been explored as methane storage systems due to their exceptionally high surface areas and chemically tunable structures. MOFs are infinite networks formed by metal units (isolated atoms or clusters) that are joined together by at least di-coordinated organic ligands. The strong metal-ligand bonds provide a great mechanical and thermal stability, and a well-defined crystal structure [2]. The structural versatility nature and composition of the MOFs opens a new possibility of controlling the chemical properties of the functional groups as well as the geometry and dimensions of the pores, channels and windows of the structure, making them an interesting alternative to the specific adsorption of gases. Therefore, in this work will be shown the preliminary results of the solvothermal synthesis of Cu-BTC (Copper -benzene -1,3,5- tricarboxylate) and Fe-BTC (Iron -benzene -1,3,5- thricarboxylate) MOFs which will be tested as a methane storage materials. The search for materials with structural characteristic that allow the gases absorption, whether greenhouse gases (CH4) or storage of energy carriers such as (H2), is today one of the main research lines in the scientific community [3].
This contribution reports the synthesis, evaluation of two metal organic frameworks (MOFs), Fe-BTC and Cu-BTC for hydrogen storage and methane capture.
The Cu3(BTC)2 and Fe-BTC was synthesized by the method of solvothermal synthesis [4]. The product was dried at room temperature for 48 h. The crystallinity and the purity of the product were analized by X-ray powder diffraction (Figure 1 and 3). Infrared spectroscopy were used to identify and follow the functional groups present in the sample, while ultraviolet spectroscopy helps to see the absorbance of the sample which can be associated to the metal center and organic entities present in the new compound, The thermogravimetric analysis is a complementary technique because it helps us see through weight loss composition of our material (Figure 2 and 4). All these results will be presented and discussed deeply during the meeting.
The x-ray diffraction of high resolution is based on measuring the direction of the x-ray photons incident and diffracted as well as the optimization of the monochromaticity of its energy, with a very high angular resolution which would be coupled to a synchrotron a tool with which we could elucidate the crystal structure and we would get a better resolution.
UNPA MESYRUM 2014
132
[1] M. Gallo and D. Glossman-Mitnik, J. Phys. Chem. C, 2009, 113, 6634-6642.. [2] Trevor A. Makal, Jian-Rong Li, Weigang Lu and Hong-Cai Zhou., 2012, Methane storage in advanced
porous materials. [3] Kuppler Ryan, J. , Timmons Darren, et. al.; Potential applications of metal-organic frameworks, C. Chem. Reviews, (2009), 253, 3042-3066. [4] J. Getzschmann, I. Senkovska, D. Wallacher, M. Tovar, D. F. Jimenez, T.Duren and J. M. Buten; Microporous and Mesoporous Materials 136 (2010) 50-58.
Figure 1. X-‐ray diffraction pattern of Cu-‐BTC (Copper -‐benzene -‐1,3,5-‐ tricarboxylate) synthetized by the solvothermal method.
Figure 2. Thermogravimetric analysis of Cu-‐BTC
0 10 20 30 40 50 603000
4000
5000
6000
7000
8000
9000
Intens
ity
2θ
Figure 3. X-‐ray diffraction pattern of Fe-‐BTC (Iron -‐benzene -‐1,3,5-‐ thricarboxylate)synthetized by the solvothermal method.
50 100 150 200 250 300 350 400 450 500 550 600
20
30
40
50
60
70
80
90
100
110
Pes
o [%
]
T empera tura [0C ]
0,0
0,5
1,0
1,5
Derv. P
eso [%/ 0C
]
Figure 2. Thermogravimetric analysis of Fe-‐BTC
0 5 10 15 20 25 30 35 40 45 50 55 60
0
2000
4000
6000
8000
10000
12000
14000
Intensity
2Θ
50 100 150 200 250 300 350 400 450 500
40
50
60
70
80
90
100
6% w
Weigh
t [%]
T empera ture °C
80°C
180°C
390°C
7% w
0,0
0,5
1,0
1,5
47% w
Deriv
. weig
ht [%
/°C]
UNPA MESYRUM 2014
133
Synthesis and characterization of MgO compounds with MnO2 and B impurities, as potential hydrogen storage materials.
A. Martinez-Garcia a, S. C. Altamirano Perez a, M. Avalos-Borja b, E. Reguera c, E. A. Juarez-Arellano d
a División de Estudios de Posgrado, Universidad del Papaloapan, Campus Tuxtepec. Circuito central #200, Col.
Parque Industrial, Tuxtepec, Oax, C.P. 68301, México. [email protected] b Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José, Col. Lomas, sección
4, San Luis Potosí, S.L.P, C.P. 78216, México. c Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaría, Instituto Politécnico
Nacional, México, D.F., C.P.1150, Mexico. d Instituto de Química Aplicada, Universidad del Papaloapan, Campus Tuxtepec, Circuito central 200, Col.
Parque Industrial, Tuxtepec, Oax, C.P. 68301, México.
Keywords: Hydrogen storage materials, MgO, additives.
Abstract
Recently, the hydrogen storage capacity of magnesium-based alloys (Mg) has been explored intensively.. There are two main problems with magnesium-based hydrides: the absorption-desorption kinetics (slow diffusion of hydrogen into the magnesium particles) and the great reactivity of magnesium with the oxygen and the humidity of the atmosphere generates the formation of magnesium oxide and magnesium hydroxide, respectively [1-3]. Metal transition oxides have several applications due to its high gas adsorption capacity that made them suitable for catalysis, as a sensor or storage applications. Recently, the use of magnesium oxide as an additive in hydrogen storage materials has been explored [4]. The effect of ceramic additives as CrCl3, Cr2O3, CuO, Nb2O5, SiC, TiO2, V2O5, Mn2O3, Cr2O3 and TiO2 favor the of absorption and desorption kinetics in the magnesium based compounds, moreover, the implementation of the B in magnesium base materials have recently acquired a potential interest because they have high gravimetric hydrogen [5]. Approximately since 25 years, several research groups started using mechanical milling as activation method and hydrogen storage materials synthesis [6, 7]. The mechanical milling has allowed study the status of modification of the microstructure of the alloys in hydrogenation kinetics [8, 9]. In this work we analysing the effect of the mechanical milling on the morphology and microstructure of magnesium oxides with MnO2 and B impurities, at different compositions. The milling products were characterized by XRD, ATG, DSC, SEM, TEM, Surface Area and CPI. The results of the characterization determined that the composition 50% MgO-50% MnO2 (figure 1) has the highest hydrogen storage capacity, and B heighten the hydrogen storage capacity. Therefore considering the hydrogen storage conditions the compounds of MgO-MnO2-B have potential application as hydrogen storage materials. But Science and technology in relation to hydrogen storage materials are now advancing toward the nanometer scale to determine the interaction structural and electronics properties of materials with the hydrogen during hydrogenation and dehydrogenation processes, which can not be characterized by techniques after mentioned, for this reason it is indispensable the use of higher resolution techniques such as synchrotron light that provides information on structural and electronic properties..
UNPA MESYRUM 2014
134
Figure 1. Pressure-Composition Isotherms (PCI) of H2 in mixtures of MgO-MnO2 after 640 minutes of milling.
1. F. D. Manchester, D. Khatamian, “Mechanisms for activation of intermetallic hydrogen absorbers”, Mater
Sci Forum, 31 (1988) 261-269. 2. A. Zaluska, L. Zaluski, JO. Ström-Olsen, “Nanocrystalline magnesium for hydrogen storage”, J Alloys
Compd, 288 (1999) 217-25. 3. J. Huot, G, Liang, S. Boily, A. Van Neste, R. Schulz, “Structural study and hydrogen sorption kinetics of
ball-milled magnesium hydride”, J Alloys Compd, 293 (1999) 495-500. 4. Xiang Sun, Hwang Jiann-Yang, Shangzhao Shi, “Hydrogen storage in mesoporous metal oxides with
catalyst and external electric field”, J Phys Chem C, 114 (2010) 7178-7184. 5. J. Huot, D. B. Ravnsbæk, J. Zhang, F. Cuevas, M. Latroche, T. R. Jensen, “Mechanochemical synthesis of
hydrogen storage materials”, Prog Mater Sci, 58 (2013) 30-75. 6. M. Y. Song, E. I. Ivanov, B. Darriet, M. Pezat, P. Hagenmuller, “Hydriding properties of a mechanically
alloyed mixture with a composition Mg 2 Ni”, Int J Hydrogen Energy, 10 (1985) 169-178. 7. J. H. Harris, W. A. Curtin, L. Schultz, “Hydrogen storage characteristics of mechanically alloyed
amorphous metals”, J Mater Res, 3, (1988) 872-883. 8. J. R. Ares, F. Cuevas, A. Percheron-Guégan. “Mechanical milling and subsequent annealing effects on
microstructural andhydrogenation properrties of multisubstituted LaNi5 alloy”, Acta Mater, 53 (2005) 2157-2167.
9. J. Gröbner, D Mirkovic, M. Ohno, “Experimental investigation and thermodynamic calculation of binary Mg-Mn phase equilibria”. JPEDAV, 26 (2005) 234-239.
UNPA MESYRUM 2014
135
Study of the chemical and physical behavior of the composite EVA-Mgspe
Guadalupe Palacios Hernándeza, Alejandro Aparicio-Saguilánb, Mario Valera Zaragozab, Erick A. Juarez-Arellanob
aDivisión de estudios de posgrado, Universidad del Papaloapan, Campus Tuxtepec, Circuito central 200, Col.
Parque Industrial, Tuxtepec, Oaxaca, México. C.P 68301. bInstituto de Química Aplicada, Universidad del Papaloapan, Campus Tuxtepec, Circuito central 200, Col.
Parque Industrial, Tuxtepec, Oaxaca, México C.P. 68301. Email:[email protected]
Keywords: copolymer, ethylene vinyl acetate, magnesium, composite and single screw extrusion Abstract Today hydrogen (H2) is considered as an energy vector. The main problems that the hydrogen is stored, so that leads to the exploration of many systems and processes of study. So in this paper we focus on metal hydrides, especially magnesium hydride (MgH2). Unfortunately magnesium ((Mg) has disadvantages as its reaction with oxygen and its contact with the environment. A solution is to encapsulate the Mg in a polymer having the property of selective permeability [2]. The copolymer has a characteristic that is ethylene vinyl acetate (EVA), this copolymer also consists of two components ethylene and vinyl acetate (VA). Course to others at different percentage of VA gives different properties to EVA copolymer, mainly permeability. The aim of this study was to determine the chemical and physical behavior of the composite EVA- Mgesp at different percentages of VA (18, 28, 40) and different species of magnesium (Mgesp; Mg, MgO, Mg (OH)2 y MgH2). They will make the process developed by single screw extrusion. So far, we conducted preliminary testing of a composite material (EVA-Mgb) with EVA copolymer at different percentages of VA (18, 28 and 40%) and two species of magnesium as base (Mgb = Mg+ Mg (OH)2,, to adjust the processing parameters such as material content of the raw material compound, the method of feeding into the extruder, temperatures, rpm, etc. The material studied was tried three times in the single-screw extruder. Was performed EVA-Mgb characterization SEM, FTIR and XRD results obtained with been concluded with SEM micrograph observe that Figure 1 is achieved Mgb dispersed in the EVA. The result of FTIR 2 analyze the signal Mgb are sobrelapadas by EVA and patterns of x-ray diffraction of EVA and EVA-Mgb Figure 3 after three extrusion processing, it was observed that the crystal structure of the material changes. This is where the synchrotron analysis would be helpful to know which would achieve both our processed material is displeased at the three different processing, which is the processing (E1, E2 and E3) where we better dispersion of our Mgesp. Technique ray scattering xa low angle (Small Angle X-Ray Scattering) is a powerful tool in determining shape and size of macromolecules, particles and aggregates with dimensions ranging from 10 A to about 1000 A, would achieve observe interaction between our composite materials. It is also known that the X-ray fluorescence (XRF) is a widely used to determine concentrations of chemical elements in a variety of matrices technique. Exploring the development macro and micro-structure associated with crystallization in polymer materials can be achieved using small and wide angle X-ray scattering techniques (SAXS / WAXS). Here, SAXS probes the long-range order or macrostructure and WAXS provides information on the level of microstructure [1]. It is important to know in detail the chemical and physical behavior of our composite EVA-Mgesp for possible application as hydrogen buffer material. [1] Heeley, E.L.; Gough, T.; Bras, W.; Gleeson, A.J.; Coates, P.D. and Ryan, A.J. (2005). Polymer processing: Using synchrotron radiation to follow structure development in commercial and novel polymer materials. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 238(1-4), pp. 21–27. [2] Ki-joon Joen, Hoi Ri Moon, Anne M. Ruminski, Bin Jiang, Christian Kisielowski, Rizia Bardhan and Jeffrey J. Urban (2011). Air. Stable magnesium nanocomposites provide rapid and high-capacity hydrogen storage without using heavy-metal catalysts.Nature materials 2978
UNPA MESYRUM 2014
136
.
Figure 1. SEM micrographs obtained by EVA18MgbE3
Figure 3 Patterns X-‐ray (RXD) EVA40Mgb (E1, E2, y E3)
Figure 2. FTIR results of EVA 40, Mgb and and EVA-‐Mgb (E1, E2, y E3)
UNPA MESYRUM 2014
137
Two applications of the synchrotron radiation for characterization of hydrogen storage and hydrogen fuel cell materials
Karina Suárez Alcántara a
a Unidad Morelia del Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México. Antigua carretera a Pátzcuaro 8710, Col. Ex-hacienda de San José de la Huerta, Morelia, Michoacán, 58190,
México. Email: [email protected]
Keywords: hydrogen storage, electrocatalyst for fuel cell, in-situ X-ray diffraction, X-ray absorption spectroscopy. The synthesis or production of innovative materials for hydrogen technologies is a key factor in the development of the so called hydrogen economy. Hydrogen storage materials and electrocatalysts are the main components of the hydrogen storage tanks and PEM fuel cells (PEMFCs), respectively. Even the knowledge of these materials have progressed in recent years, a deeper knowledge is mandatory for materials optimization. Synchrotron radiation characterization techniques are ideal for that purpose. In-situ X-ray diffraction is particularly useful in the determination of hydrogen sorption/ desorption pathways. X-ray absorption spectroscopy is useful in the determination of electronic configuration of electrocatalysts. Two examples, one of each technique, are presented. Hydrogen storage materials. At present, no single hydride material fulfills all the requirements for hydrogen storage applications on capacity, fast kinetics and enthalpy. The hydrogen desorption enthalpy is a directing feature because it translates into hydrogen desorption temperature, and finally into the feasibility of an intended application. Several methods for enthalpy adjustment have been proposed; among them stand out the anion substitution, cation substitution, and the reactive hydride composites (RHC). In the RHC approach, two hydrides react each other to form a new compound. This formation is exothermic, and thus, the overall reaction enthalpy is lowered; allowing for high hydrogen capacities and lower reaction temperatures [1]. The RHC system Ca(BH4)2 + MgH2 ↔ CaH2 + MgB2 + 4H2 (Ca-RHC) is predicted, based on thermodynamic data, to have a desorption temperature of 135 °C at 1 bar and to store 8.4 wt.% of hydrogen. Experimetally, this have no achieved, and the use of aditives have been proposed as a way to improve its sorption/ desorption characteristics. The purpose of the work with in-situ synchrotron radiation powder X-ray diffraction (SR-PXD) was to determine the hydrogen desorption reaction pathway at Ca-RHC doped with fluorinated compounds. The in-situ SR-PXR have been useful in determining the effects of the fluorinated compounds in the kinetics and hydrogen uptake on the Ca-RHC. Figure 1 presents the hydrogen desorption reaction on the Ca-RHC doped with CaF2. The system presents a great deal of complexity regarding the number of phases and the changes triggered by the temperature increase. Also it can be observed the presence of unidentified reaction intermediaries do not observed in the undoped system [2]. Electrocatalysts for PEM fuel cells. The main objectives in the development of PEMFCs electrocatalysts are the reduction of Pt loading and the increase of electrochemical activity. Both objectives have been complied in some degree by the formation of Pt alloys or core-shell structures. The increased electrochemical activity have been explained based on the geometric and electronic changes produced by the Pt-M (M = non precious metal) alloying or M-core/Pt-shell formation. These geometric and electronic changes can be “directly” observed by means of (synchrotron radiation) X-ray absorption spectroscopy at the Pt L3-edge. Extended X-ray adsorption fine structure (EXAFS) at the Pt L3-edge of Pt foil, Pt ETEK, ball milled Co0.25Pt0.75 and ball milled Ni0.25Pt0.75 are presented in the Figure 2. Here the electronic changes produced by the nano-alloying at Co0.25Pt0.75 and Ni0.25Pt0.75 shaped important changes after the Pt L3-edge. Figure 3 presents EXAFS Fourier transformation of the signal, in this plot it can be observed the changes in the bond distances upon nano-alloying, i.e. a shortening in the bond distance Pt-M (M=Co, Ni). Finally Figure 4 collects the electrochemical activity (as exchange current density, j0), the Pt d-band vacancies and the bond distances (both obtained by means of the Pt L3-edge
UNPA MESYRUM 2014
138
EXAFS). It is clear that a change in the geometric and electronic configuration of Pt d-band upon alloying is related with the electrochemical activity. [1] K. Suarez Alcantara, J. M. Ramallo-Lopez, U. Boesenberg, I. Saldan, C. Pistidda, F. G. Requejo, T. Jensen, Y. Cerenius, M. Sørby, J. Avila, J. Bellosta von Colbe, K. Taube, Thomas Klassen, M. Dornheim. Journal of Physical Chemistry C 116 (2012) 7207−7212. [2] G. Barkhordarian, T. Klassen, M. Dornheim, R. Bormann. Journal of Alloys and Compounds 440 (2007)
L18–L21. [3] C. A. Cortés-Escobedo, R. G. González-Huerta, A. M. Bolarín-Miró, F. Sánchez de Jesús, Q. Zhu, S.E. Canton, K. Suarez-Alcantara, M. Tufiño-Velazquez. International Journal of Hydrogen Energy 39 (2014) 16722-16730.
11500 11600 11700 11800 11900 12000
P t L 3-‐edge
Norm
aliz
ed intensity [a.u.]
P hoton E nerg y [eV ]
N i0.25
P t0.75
C o0.25
P t0.75
P t E T E K P t foil
Figure 1. Hydrogen desorption at Ca(BH4)2 + MgH2 → CaH2 + MgB2 + 4H2 doped with CaF2 (ESRF synchrotron)
Figure 2. EXAFS at the Pt L3-edge of Pt foil, Pt ETEK, ball milled Co0.25Pt0.75 and ball milled Ni0.25Pt0.75 (MAX-lab synchrotron)
0 1 2 3 4 50
5
10
15
20
25
30P t-‐M bond
P t foil P t E T E K C o
0.25P t
0.75
N i0.25
P t0.75
R [Å]
|x(R
)| [Å
-‐4]
P t-‐P t bond
2.60 2.65 2.70 2.75 2.80 2.851.2x10-‐4
1.3x10-‐4
1.4x10-‐4
1.5x10-‐4
P t etek
N i0.75P t0.25
C o0.75P t0.25
P t etek
N i0.75P t0.25
C o0.75P t0.25
P t d-‐band vacancy per a tom
j 0 / m
A cm
-‐2
j 0 / m
A cm
-‐2
B ond dis tance P t-‐M (M=P t, N i, C o) /Å
0.338 0.336 0.334 0.332 0.330 0.328 0.326
1.2x10-‐4
1.3x10-‐4
1.4x10-‐4
1.5x10-‐4
Figure 3. EXAFS Fourier transformation, showing the Pt-M (M=Co, Ni) bond distance shortening (MAX-lab synchrotron)
Figure 4. Electrochemical activity, Pt d-band vacancy and bond distance at Pt foil, Pt-ETEK¸ ball milled Co0.25Pt0.75 and ball milled Ni0.25Pt0.75
UNPA MESYRUM 2014
139
![[UNPA] NEW OLD DIETARY INGREDIENTS LIST PAGE 1 …/media/Supporting Documents/Th… · [UNPA] NEW OLD DIETARY INGREDIENTS LIST PAGE 1 OF 57 Original Text & Key Matched Full Latin](https://static.fdocuments.net/doc/165x107/5ab554dc7f8b9adc638ce391/unpa-new-old-dietary-ingredients-list-page-1-mediasupporting-documentsthunpa.jpg)
![[Copia conforme] UNPA-CLE - Prot. 34246-22/04/2020 - Rep ... · [Copia conforme] UNPA-CLE - Prot. 34246-22/04/2020 - Rep. Delibere Senato accademico n. 119/2020](https://static.fdocuments.net/doc/165x107/5ff43b25099a9f2b9a46dc57/copia-conforme-unpa-cle-prot-34246-22042020-rep-copia-conforme-unpa-cle.jpg)
