Materials, Objects and Materials, Objects and TechnologiesTechnologies

13. New Challenges, New 13. New Challenges, New Materials Materials

What Do You Know About It?What Do You Know About It? Why do you think these materials are Why do you think these materials are

piece of news? Which features do they piece of news? Which features do they have to be considered as new materials?have to be considered as new materials?

Which is your opinion and your personal Which is your opinion and your personal interest about these new materials?interest about these new materials?

Carbon fiber, optical fiber and carbon Carbon fiber, optical fiber and carbon nanotubes are usually in nature or they nanotubes are usually in nature or they have been synthesized artificially? How do have been synthesized artificially? How do you know it? Read your textbookyou know it? Read your textbook

Which other natural or synthetic materials Which other natural or synthetic materials do they replace? Which improvements do do they replace? Which improvements do they show regarding the older ones?they show regarding the older ones?

Considering the definition of carbon Considering the definition of carbon nanotubes and the explanation about what nanotubes and the explanation about what scientists do with them, how would you scientists do with them, how would you define nanotechnology? Which impact may define nanotechnology? Which impact may it have in other fields, besides biomedicine?it have in other fields, besides biomedicine?

According to you, which problems could be According to you, which problems could be originated by these and other new originated by these and other new materials?materials?

Materials ScienceMaterials Science Materials science Materials science is the name we give to is the name we give to

the field of science and engineering that the field of science and engineering that studies the studies the relations between materials relations between materials structurestructure and its and its properties properties and also its and also its processing processing techniques and its techniques and its behaviorbehavior

Materials have been historically related with Materials have been historically related with economic and social developmenteconomic and social development

We may divide Prehistory in We may divide Prehistory in CopperCopper Age, Age, BronzeBronze Age or Age or IronIron Age, according to the Age, according to the metal or alloy they used thenmetal or alloy they used then

Present-day society lives in Present-day society lives in SiliconSilicon Age, Age, because of the significance of Electronicsbecause of the significance of Electronics

The 20The 20 thth century is considered century is considered Plastic Plastic AgeAge Materials that a society owns are a Materials that a society owns are a mirror mirror

of its lifestyleof its lifestyle, its , its knowledgeknowledge and and scientific scientific and technological abilitiesand technological abilities

Materials Science is an Materials Science is an interdisciplinaryinterdisciplinary science: one material is featured by its science: one material is featured by its physical and chemical propertiesphysical and chemical properties but also by but also by its its biological compatibilitybiological compatibility

It is an It is an appliedapplied science, because its aim is science, because its aim is not only knowing materials, but also not only knowing materials, but also processing them and designing objects that processing them and designing objects that be useful at an be useful at an economic and environmental economic and environmental sustainable costsustainable cost

Physical Physical properties : density, thermal properties : density, thermal conductivity, electric resistivity, magnetic conductivity, electric resistivity, magnetic permeability, elasticity, hardness, fragility...permeability, elasticity, hardness, fragility...

Chemical Chemical properties: reactions that properties: reactions that transform materialtransform material’’s nature, oxidation, s nature, oxidation, acidity or alkalinity (reaction against pH), acidity or alkalinity (reaction against pH), chemical stability in generalchemical stability in general

Biological compatibility Biological compatibility is regarded is regarded whether material can be used in whether material can be used in organisms or living tissues without organisms or living tissues without provoking immunologic rejection or non provoking immunologic rejection or non desired toxic effectsdesired toxic effects

Structure: Structure: Atomic, Micro and Macro LevelsAtomic, Micro and Macro Levels

At an At an atomic scaleatomic scale we are interested in we are interested in which which atomsatoms or or moleculesmolecules constitute them constitute them

Which type of Which type of interactionsinteractions do exist between do exist between them: metallic, ionic or covalent bonds, Van them: metallic, ionic or covalent bonds, Van der Waals forces, hydrogen bondsder Waals forces, hydrogen bonds

Which type of Which type of organizationorganization do they contain: do they contain: crystalline (ordered) or amorphous crystalline (ordered) or amorphous (disordered)(disordered)

MicrostructureMicrostructure refers to whether it is formed by refers to whether it is formed by fibers, tubes, sheets or microscopic poresfibers, tubes, sheets or microscopic pores

MacrostructureMacrostructure refers to the aspect at our scale: refers to the aspect at our scale: visible parts of a material composed of many visible parts of a material composed of many othersothers

We must know that We must know that one materialone material’’s behavior s behavior ((““allall””) does not equal the addition of its ) does not equal the addition of its components (components (““partsparts””) )

DefectsDefects play an important role. Perfect crystals play an important role. Perfect crystals are impossible to obtain, but interesting are impossible to obtain, but interesting properties stem from their defects: properties stem from their defects: interstitial interstitial elementselements, , empty positionsempty positions and and substitutionssubstitutions. . Many materials are amorphous Many materials are amorphous

Metals and New Metallic MaterialsMetals and New Metallic Materials

According to their origin, materials can be According to their origin, materials can be naturalnatural or or artificialartificial. According to their structure . According to their structure and properties there are three main groups: and properties there are three main groups: metalsmetals, , ceramicsceramics and and polymerspolymers. There are also . There are also composed materials composed materials from those groupsfrom those groups

MetalsMetals are electropositive, easily give or share are electropositive, easily give or share electrons. They have a structure made up of electrons. They have a structure made up of crystal lattices crystal lattices formed by positive ions formed by positive ions surrounded by free electronssurrounded by free electrons that can be given that can be given to more electronegative elements and form to more electronegative elements and form ionicionic bonds or share between metals (bonds or share between metals (metallicmetallic bonds) bonds)

Properties: good heat and electricity Properties: good heat and electricity conductorsconductors, , high high densitydensity, solid at ordinary temperature (, solid at ordinary temperature (high high melting pointsmelting points), light reflecting (metallic ), light reflecting (metallic brightnessbrightness), they are ), they are hardhard, , ductileductile and and malleablemalleable. Some have . Some have magneticmagnetic properties properties (Fe, (Fe, Co, Ni), others (Au, Pt, Ag, Cu, Al) have a very Co, Ni), others (Au, Pt, Ag, Cu, Al) have a very weak magnetismweak magnetism

They form They form alloysalloys with each other. An alloy is a with each other. An alloy is a solid mixture of different metals. Their original solid mixture of different metals. Their original properties are modified: color, mechanical properties are modified: color, mechanical resistance, resistance to corrosion. The first one resistance, resistance to corrosion. The first one to be found in history was to be found in history was bronzebronze: copper and : copper and tin, it improved hardness and resistance of tin, it improved hardness and resistance of copper and started the age of metallurgycopper and started the age of metallurgy

NEW METALLIC MATERIALSNEW METALLIC MATERIALS: the most : the most interesting innovation in the world of metals interesting innovation in the world of metals is the production of is the production of shape-memory alloysshape-memory alloys. . After being deformed they have the capacity After being deformed they have the capacity of remembering their earliest shape, of remembering their earliest shape, because because deformations are displacements of deformations are displacements of the original crystal latticethe original crystal lattice. The new lattice is . The new lattice is not much symmetrical and becomes not much symmetrical and becomes unstable. When you heat it up or set it free, unstable. When you heat it up or set it free, the structure goes back to the earlier the structure goes back to the earlier situation and metal recovers its original situation and metal recovers its original shape (Nitinol: nickel and titanium)shape (Nitinol: nickel and titanium)

Surgical prosthesis made of NITINOL, whenit is implanted it expands due to human body’stemperature

http://www.acceleratingfuture.com/michael/blog/2008/04/ten-futuristic-materials/

Ceramics and New Ceramic MaterialsCeramics and New Ceramic Materials

Traditional ceramics Traditional ceramics are made up of are made up of silicates and have been used in silicates and have been used in craftsmanshipcraftsmanship (clay, porcelain) and (clay, porcelain) and structural materials structural materials (bricks, glass, concrete)(bricks, glass, concrete)

TechnicalTechnical or advanced or advanced ceramics ceramics contain contain metallic and non-metallic elements making metallic and non-metallic elements making up oxides (Al, Zr), carbides, nitrates and up oxides (Al, Zr), carbides, nitrates and boratesborates

ApplicationsApplications: space shuttle covering, engine : space shuttle covering, engine components, artificial bones and teeth, components, artificial bones and teeth, electronics, powerful magnets, optic fibers, electronics, powerful magnets, optic fibers, cutting tools, ovens and sensorscutting tools, ovens and sensors

All ceramicsAll ceramics have in common that have in common that they are they are refractory, inorganic and non-metallic refractory, inorganic and non-metallic materials materials

They are usually They are usually crystallinecrystalline, excepting , excepting glasses that are amorphous, and have very glasses that are amorphous, and have very strong ionic or covalent bondsstrong ionic or covalent bonds

Ceramics Ceramics are preparedare prepared from powder, from powder, natural or chemically synthesized, natural or chemically synthesized, in in ovens at very high temperaturesovens at very high temperatures (1500- (1500-2400 2400 °°C)C)

They have They have a low thermal and electrical a low thermal and electrical conductivity conductivity (some are semiconductors (some are semiconductors and other even superconductors at very and other even superconductors at very low temperatures), they have low temperatures), they have a high a high hardnesshardness (like diamonds) but are also (like diamonds) but are also fragilefragile (breakable) and not much plastic. (breakable) and not much plastic. They are They are resistant to corrosionresistant to corrosion

New ceramic materials New ceramic materials have very different have very different usesuses

Smart ceramics Smart ceramics are used in sensors and are used in sensors and actuators, like actuators, like electrochromic glasseselectrochromic glasses, that , that change their color with heat, or change their color with heat, or piezoelectric piezoelectric or pyroelectric sensorsor pyroelectric sensors, that detect changes , that detect changes in mechanical tension or temperature and in mechanical tension or temperature and convert them into electrical voltageconvert them into electrical voltage

As a future challenge there are As a future challenge there are hyperfiltration ceramic membranes hyperfiltration ceramic membranes at a at a molecular scale and molecular scale and superhard ceramics superhard ceramics to to make coverings and improving their ductilitymake coverings and improving their ductility

PolymersPolymers Formed by Formed by very large moleculesvery large molecules, of an , of an

organic origin usuallyorganic origin usually Some Some structuralstructural units, units, called called monomersmonomers, ,

are repeated. They are united by means are repeated. They are united by means of covalent bondsof covalent bonds

Frequently polymers are related with Frequently polymers are related with plasticsplastics, but , but cellulosecellulose, , DNADNA and and proteins proteins are also polymersare also polymers

Some polymers with a Some polymers with a naturalnatural origin are origin are well known from ancient times: silk, rubber, well known from ancient times: silk, rubber, shellacshellac

The ones we usually use today are mainly The ones we usually use today are mainly syntheticsynthetic: tissues, packing, frames for toys : tissues, packing, frames for toys and electric devices, cable and electric and electric devices, cable and electric components insulationcomponents insulation

Properties: Properties: mechanical resistance mechanical resistance (capacity (capacity to bear tensions without breaking) and to bear tensions without breaking) and elasticityelasticity (capacity to deform without (capacity to deform without breaking)breaking)

Specific properties Specific properties of a polymer depend of a polymer depend on the monomer and type of bond formed: on the monomer and type of bond formed: Van der Waals forces, hydrogen bondsVan der Waals forces, hydrogen bonds

By combining resistance and elasticityBy combining resistance and elasticity different kinds of polymers are obtained: different kinds of polymers are obtained: rigid fibers, flexible plastics, elastomersrigid fibers, flexible plastics, elastomers

They have a They have a low electric and thermal low electric and thermal conductivityconductivity, because of containing , because of containing covalent bonds where electrons are covalent bonds where electrons are immobilized and due to the long size of immobilized and due to the long size of monomers that makes vibration difficultmonomers that makes vibration difficult

WATER ABSORTION POLYMER: BALLS BLOW UP

PLASTICS FLOATING AT “THE GREAT PACIFIC GARBAGE PATCH”

http://www.youtube.com/watch?v=uLrVCI4N67M

http://en.wikipedia.org/wiki/Great_Pacific_Garbage_Patch

BiomaterialsBiomaterials These materials are These materials are compatible with living compatible with living

tissues and organisms tissues and organisms with which they with which they interactinteract

Many of them are used in medical Many of them are used in medical applications: metals like applications: metals like titaniumtitanium or or biocompatible ceramics biocompatible ceramics for practicing for practicing bone implants with the minimum patientbone implants with the minimum patient’’s s rejection and systems to supply medicines rejection and systems to supply medicines with a time regulationwith a time regulation

Materials for a More Efficient Materials for a More Efficient World: Carbon FiberWorld: Carbon Fiber

Very well known material because of its Very well known material because of its extraordinary extraordinary resistance and lightnessresistance and lightness, , what allows to reduce fuel use in transportwhat allows to reduce fuel use in transport

The The high manufacturing costs high manufacturing costs have made have made it to have an elitist use until nowit to have an elitist use until now

It is about a It is about a composed materialcomposed material, , manufactured from a manufactured from a polymer matrix polymer matrix (epoxy resin) reinforced (epoxy resin) reinforced with carbon fiberswith carbon fibers

Each fiber is made up of Each fiber is made up of thousands of carbon thousands of carbon filamentsfilaments between 5 and 8 between 5 and 8 μμm diameterm diameter

As it is a As it is a composed material composed material it combines it combines features from the features from the matrixmatrix (sticky, hard and elastic (sticky, hard and elastic resin) with those of resin) with those of fibers fibers (very resistant) to form (very resistant) to form a a ““tissuetissue”” with with a high resistance, lightness and a high resistance, lightness and elasticityelasticity

ItIt’’s the very best material for s the very best material for framesframes that can be that can be designed to measuredesigned to measure

It is good for It is good for thermal insulation thermal insulation and has and has fire-fire-retardant properties retardant properties

The only inconvenient is a The only inconvenient is a high manufacture high manufacture costcost

http://www.renovat.org/energia-medi-ambient/materials/la-fibra-de-carboni

EPOXY RESIN MADEBY VACUUM INFUSION

BOEING 787 COCKPIT

BOEING 787 DREAMLINER INSIDE

Materials for a More Global World: Materials for a More Global World: Optic Fiber and LEDOptic Fiber and LED

Without Without optic fiber optic fiber nor nor light emitting light emitting semiconductor diodes semiconductor diodes (LED), the Internet (LED), the Internet would not have been possible would not have been possible

Long distancesLong distances, where information has a , where information has a long way to run, demand materials where long way to run, demand materials where signals do not fade too muchsignals do not fade too much

Optic fiber is needed to transmit Optic fiber is needed to transmit great great volumes of informationvolumes of information (broadband) (broadband)

Optic FibersOptic Fibers They are made up of They are made up of glassglass (ceramic material) or (ceramic material) or

plasticplastic (polymer) (polymer) They are obtained making They are obtained making melt glass flow at a melt glass flow at a

very high temperature through a mesh with very very high temperature through a mesh with very thin holes thin holes and form filaments that, once they are and form filaments that, once they are solidified, they keep enough solidified, they keep enough elasticityelasticity to be used to be used as fibersas fibers

They have the same properties we know from They have the same properties we know from glass: glass: good electric and thermal insulation, high good electric and thermal insulation, high temperatures support and transparencytemperatures support and transparency

They have both a They have both a low costlow cost and and row material row material abundanceabundance

Optic fibers conduct light Optic fibers conduct light without almost without almost any fading any fading and in curve trajectoriesand in curve trajectories

The phenomenon of The phenomenon of total reflectiontotal reflection inside inside the fiber is appliedthe fiber is applied

As fibers can be made very thin, cables As fibers can be made very thin, cables with optic fiber with optic fiber transmit much more transmit much more informationinformation than traditional copper cables than traditional copper cables

They are, besides, They are, besides, light, flexible, cheap light, flexible, cheap and do not go rustyand do not go rusty

Optic fiber is not only used to transmit Optic fiber is not only used to transmit digital information, its simplest application digital information, its simplest application is is transmitting light into places difficult to transmitting light into places difficult to accedeaccede, say, inside the human body: , say, inside the human body: endoscopies, laser surgery…endoscopies, laser surgery…

They are also used as They are also used as sensorssensors of all kinds of all kinds

CAMERA WITH OPTICFIBER FOR PRACTICINGENDOSCOPIES

Laser Diodes and LEDLaser Diodes and LED The use of optic fibers has been parallel to The use of optic fibers has been parallel to

the development of new the development of new less expensive less expensive means to produce lightmeans to produce light, say, , say, laser diodes laser diodes (on pointers) and (on pointers) and LEDLED (light-emitting diode) (light-emitting diode)

It is about It is about semiconductor ceramic devices semiconductor ceramic devices (with insulating and conducting properties) (with insulating and conducting properties) that emit light when they are connected to that emit light when they are connected to an electric current in one specific direction an electric current in one specific direction but they do not let the current pass if they but they do not let the current pass if they are connected in the contrary directionare connected in the contrary direction

They have the advantage of being They have the advantage of being littlelittle, , energy-savingenergy-saving (use of 50 % less than (use of 50 % less than traditional sources), easy to traditional sources), easy to replacereplace, , cheapcheap and and lastinglasting

We are now having LED of different colors We are now having LED of different colors and also of and also of white light white light that will help to save that will help to save energy when they replace present-day energy when they replace present-day devicesdevices

SEVERAL DEVICES WITHLED AND LASER DIODES

NanotechnologyNanotechnology The new materials we have seen until now The new materials we have seen until now

are obtained by modifying internal are obtained by modifying internal composition, microstructure or composition, microstructure or macrostructure, but always to a macrostructure, but always to a macroscopic scale macroscopic scale

A great revolution has begun with the A great revolution has begun with the possibility of possibility of making a scale changemaking a scale change

It consists in treating materials to a It consists in treating materials to a scale scale between atomic and molecularbetween atomic and molecular

NanotechnologyNanotechnology is part of materials is part of materials science at this new scalescience at this new scale

It is foreseen that nanotechnology will It is foreseen that nanotechnology will have an have an impact in our lives impact in our lives similar to that similar to that of electricity in its time or modern transport of electricity in its time or modern transport systemssystems

We should think what could mean to We should think what could mean to medicine medicine news like the ones we read news like the ones we read at at the beginning of this unit regarding the the beginning of this unit regarding the technique to technique to attack malignant tumors attack malignant tumors or to or to cure cure diabetes 1diabetes 1, now in a phase of testing, now in a phase of testing

There is a long way to run full of There is a long way to run full of advantagesadvantages, but there could also be some , but there could also be some risksrisks

The Nano ScaleThe Nano Scale The name comes from the fact that the atomic The name comes from the fact that the atomic

and molecular scale is about and molecular scale is about nanometers nanometers (1 nm (1 nm = 10= 10 -9-9 m) m)

It is very difficult to manage objects there, It is very difficult to manage objects there, because because physical and chemical laws changephysical and chemical laws change: : gravity is too weak and other interactions, like gravity is too weak and other interactions, like the Van der Waals forces, become essentialthe Van der Waals forces, become essential

Besides, the Besides, the quantum effects quantum effects cannot be cannot be despised: matter behaves in a despised: matter behaves in a dual waydual way, both as , both as a wave and as a particle, there is a wave and as a particle, there is quantization of quantization of energy energy and and uncertaintyuncertainty: we are not able to : we are not able to calculate once at a time one particlecalculate once at a time one particle’’s s momentum and its positionmomentum and its position

New InstrumentsNew Instruments Nanotechnology is possible thanks to the Nanotechnology is possible thanks to the

development of development of new instrumentsnew instruments to explore to explore nature at the new scalenature at the new scale

The first one was the The first one was the STM,STM, scanning scanning tunneling microscopetunneling microscope, in which a tungsten , in which a tungsten point containing point containing ONLY ONE ATOM ONLY ONE ATOM in its in its head makes a scan and measures the head makes a scan and measures the electric nanocurrents generated between electric nanocurrents generated between the point and the sample. Atoms cannot be the point and the sample. Atoms cannot be ““seenseen””, instead we can infer their position , instead we can infer their position while scanning the sample while scanning the sample (photo page 174 (photo page 174 on your textbook)on your textbook)

S.T.M. MICROSCOPE

WORKING SCHEME

PROCESS OF ATOM MANIPULATION

“QUANTUM CORRAL” BUILD BY PLACING IRON ATOMS ONTO A COPPER SURFACE

New InstrumentsNew Instruments At present we also use the At present we also use the AFM, atomic AFM, atomic

force microscopesforce microscopes, that measure the force , that measure the force between a scan flexible microlever and the between a scan flexible microlever and the sample and can be used with non-sample and can be used with non-conductor samplesconductor samples

HOW DOES AN A.F.M. WORK?

Biomimetic NanotechnologyBiomimetic Nanotechnology Nanotechnology intends to imitate lifeNanotechnology intends to imitate life and and

is inspired in living structures, like DNA, is inspired in living structures, like DNA, that are actually nanomolecules and so that are actually nanomolecules and so does all does all the intracellular working structurethe intracellular working structure, , containing many other containing many other ““nanomachinesnanomachines””, , sets of molecules that do a lot of functionssets of molecules that do a lot of functions

Nanofuzziness of lotus leavesNanofuzziness of lotus leaves, when they , when they are wet, they form water drops that carry are wet, they form water drops that carry dirtiness away from leaves. This can be dirtiness away from leaves. This can be applied to applied to out-door paintings out-door paintings and and sanitary sanitary ceramicceramic, where water slips and keeps , where water slips and keeps them cleanthem clean

Salamanders have very slender hairs Salamanders have very slender hairs that that are placed at nanometric distances from are placed at nanometric distances from the surfaces and pull through Van der the surfaces and pull through Van der Waals forces. Synthetic hairs can interest Waals forces. Synthetic hairs can interest the world of the world of adhesivesadhesives

Sponge called Sponge called ““VenusVenus’’s baskets basket”” forms an forms an inner skeleton with silica needles and a inner skeleton with silica needles and a weft similar to a wicker basket. weft similar to a wicker basket. Sponge Sponge cells join together in extra-thin layers with cells join together in extra-thin layers with nanometric silicon oxide blocks and then nanometric silicon oxide blocks and then they wind up and form the needlesthey wind up and form the needles. The . The result is a material with a big resistance result is a material with a big resistance and high packaging which is considered and high packaging which is considered as a as a biological model for a future optic biological model for a future optic fiber designfiber design

http://mentescuriosas.es/8-ejemplos-de-inventos-inspirados-en-la-naturaleza/

Present and Future ApplicationsPresent and Future Applications

Carbon NanotubesCarbon Nanotubes Carbon nanotubes are a type of Carbon nanotubes are a type of fullerenesfullerenes, ,

tridimensional carbon molecules with tridimensional carbon molecules with different shapes and properties. The ones different shapes and properties. The ones with awith a cylinder shape cylinder shape are called are called nanotubesnanotubes

Nanotubes have an extraordinary Nanotubes have an extraordinary mechanical resistancemechanical resistance, although they are , although they are very light, and electrically they are from very light, and electrically they are from semiconductorssemiconductors to to superconductorssuperconductors and and they have a high they have a high heat conductivityheat conductivity

a) diamond; b) graphite; c) hexagonal diamond; d) fullerene C60; e) fullerene C540

f) fullerene C70; g) amorphous carbon; h) carbon nanotube

ALLOTROPESOF CARBON

WOULD THE NEW MATERIALS BE ABLETO COME THESE DREAMS TRUE?

To Learn MoreTo Learn More MIJANGOS, Carmen; MOYA, José MIJANGOS, Carmen; MOYA, José

Serafín (coord.) Serafín (coord.) Nuevos materiales en la Nuevos materiales en la sociedad del siglo XXI.sociedad del siglo XXI. Madrid: CSIC, Madrid: CSIC, 20772077Disponible en línia a:Disponible en línia a:

www.csic.es/documentos/colecciones/divulgwww.csic.es/documentos/colecciones/divulgacion/materiales.pdfacion/materiales.pdf

SCHULENGURG, Mathias. SCHULENGURG, Mathias. La La nanotecnología. Innovaciones para el nanotecnología. Innovaciones para el mundo del mañanamundo del mañana. . Luxemburg: Comissió Luxemburg: Comissió Europea, 2004Europea, 2004

Està disponible en línia a:Està disponible en línia a:ftp://ftp.cordis.europa.eu/pub/nanotechnologftp://ftp.cordis.europa.eu/pub/nanotechnology/docs/nano_brochure_es.pdfy/docs/nano_brochure_es.pdfThe Nanotube Site:The Nanotube Site:http://nanotube.msu.edu/http://nanotube.msu.edu/CRICHTON, Michael. CRICHTON, Michael. Presa. Presa. Barcelona: Barcelona: Círculo de Lectores, 2004 (Ciència ficció)Círculo de Lectores, 2004 (Ciència ficció)Crítica a:http://www.nanotech-Crítica a:http://www.nanotech-now.com/Chris-Phoenix/prey-critique.htmnow.com/Chris-Phoenix/prey-critique.htmSTEPHENSON, Neal. STEPHENSON, Neal. La era del La era del diamante. diamante. Barcelona: Ediciones B, 2004Barcelona: Ediciones B, 2004