1. NANOYOUTeachersTrainingKitinNanotechnologiesChapter2EnvironmentMODULE2ApplicationofNanotechnologiesWrittenbyLuisaFilipponiandDuncanSutherlandInterdisciplinaryNanoscienceCentreAarhusUniversity,DenmarkJanuary2010CreativeCommonsAttributionShareAlike3.0unlessindicatedintextorfigurecaptions.

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NANOYOUTeachersTrainingKitModule2Chapter2Contents(NOTE)RemediationandMitigation.......................................................................................................................................... 4Remediationusingmetalnanoparticles.................................................................................................................... 5Remediationusingsemiconductingnanoparticles.................................................................................................... 6Remediationusingdendrimers.................................................................................................................................. 7Remediationusingmagneticnanoparticles.............................................................................................................. 7Remediationusingaerogelsandsolidabsorbents.................................................................................................... 8Nanomembranesandnanofilters ........................................................................................................................... .9PollutionPrevention.................................................................................................................................................... 0 1Materials ................................................................................................................................................................. 0 .1 Lotuseffectsurfacesandtextiles........................................................................................................................ 11 Antimicrobialcoatings,textilesandotherproducts............................................................................................ 3 1 Fertilizersandwoodtreatmentproducts............................................................................................................ 5 1 Biomimeticwaterharvesting............................................................................................................................... 51Nanocatalysis .......................................................................................................................................................... 5 . 1 Catalyticgold....................................................................................................................................................... 7 1 Recoveryofcatalyticmaterial............................................................................................................................. 7 1Greenmanufacturing.............................................................................................................................................. 81EnvironmentSensing................................................................................................................................................... 9 1Nanowiresandnanotubesbasedsensors............................................................................................................... 0 2Cantileversensors.................................................................................................................................................... 1 2Page2of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 3. NANOYOUTeachersTrainingKitModule2Chapter2Chapter2: ApplicationsofNanotechnologies EnvironmentInindustrializednationstheairisfilledwithnumerouspollutantscausedbyhumanactivityorindustrialprocesses,such as carbon monoxide (CO), chlorofluorocarbons (CFC), heavy metals (arsenic, chromium, lead, cadmium,mercury,zinc),hydrocarbons,nitrogenoxides,organicchemicals(volatileorganiccompounds,knownasVOCs,anddioxins),sulphurdioxideandparticulates.Thepresenceofnitrogenandsulphuroxideintheairgeneratesacidrainthatinfiltratesandcontaminatesthesoil.Theelevatedlevelsofnitrogenandsulphuroxideintheatmospherearemainlyduetohumanactivities,particularlyburningofoil,coalandgas.Onlyasmallportioncomesfromnaturalprocesses such as volcanic action and decay of soil bacteria. Water pollution is caused by numerous factors,including sewage, oil spills, leaking of fertilizers, herbicides and pesticides from land, byproducts frommanufacturingandextractedorburnedfossilfuels.Contaminants are most often measured in parts per million (ppm) or parts per billion (ppb) and their toxicitydefinedbyatoxiclevel.Thetoxiclevelforarsenic,forinstance,is10ppminsoilwhereasformercuryis0.002ppminwater.Therefore,verylowconcentrationsofaspecificcontaminantcanbetoxic.Inaddition,contaminantsare mostly found as mixtures. Consequently, there is a need for technologies that are capable of monitoring,recognizing and, ideally, treating such small amount of contaminants in air, water and soil. In this context,nanotechnologiesoffernumerousopportunitiestoprevent,reduce,senseandtreatenvironmentcontamination.Nanotechnologiescanenhanceandenablepreexistingtechnologiesanddevelopnewones.What can nanotechnologies do? Nanotechnologies offer the ability to control matter at the nanoscale level tocreate materials with specific properties that can serve specific functions. This is particularly important inenvironmentalissueswherepollutionoftenarisesfromthepresenceofaspecificcontaminantwithinamixtureofmaterials, being either in a solid, liquid or gas form. The small size of nanomaterials, together with their highsurfacetovolume ratio, can lead to very sensitive detection. These properties will allow developing highlyminiaturize, accurate and sensitive pollutionmonitoring devices (nanosensors). Nanomaterials can also beengineered to actively interact with a pollutant and decompose it in less toxic species. Thus, in the futurePage3of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 4. NANOYOUTeachersTrainingKitModule2Chapter2nanotechnology could be used not only for detecting contaminated sites but also treating them. Finally, thistechnologycanbeusedtoreducetheproductionofharmfulwastesinmanufacturingprocessesbyreducingtheamountofmaterialused,andbyemployinglesstoxiccompounds.Anotherapplicationareaistheengineeringofcoatingsthatarenanostructuredinawaythattheyresisttheattackof pollutant or have selfcleaning properties so that get easily cleaned by rain water and therefore require lessdetergentstobewashed.Thestartingpointtodiscusstheapplicationsofnanotechnologiestotheenvironmentistheabilityofnanoscienceto create new nanostructured materials with specific properties to serve specific functions. These aspects werepreviouslydiscussedinModule1,Chapter4and5.RemediationandMitigationSoilandgroundwatercontaminationarisingfrommanufacturingprocessesareamatterofgreatcomplexityandconcern. Affected sites include contaminated industrial sites (including lakes and rivers in their vicinity),undergroundstoragetankleakages;landfills;andabandonedmines.Pollutantsintheseareasincludeheavymetals(e.g., mercury, lead, cadmium) and organic compounds (e.g., benzene, chlorinated solvents, creosote).Nanotechnology can develop techniques that will allow for more specific and costeffective remediation tools.Currently,manyofthemethodsemployedtoremovetoxiccontaminantsinvolvelaborious,timeconsumingandexpensive techniques. A pretreatment process and removal of the contaminated area is often required, with aconsequent disturbance of the ecosystem. Nanotechnology allows developing technologies that can perform insitu remediation and reach inaccessible areas such as crevices and aquifers, thus eliminating the necessity forcostly pumpandtreat operations. In addition, thanks to its ability to manipulate matter at a molecular level,nanoscience can be used to develop remediation tools that are specific for a certain pollutant (e.g., metal),thereforeincreasingaffinityandselectivity,aswellasimprovingthesensitivityofthetechnique.Drinkingwaterqualityanditscontaminationfrompollutantsisanothermatterofconcern.Mercuryandarsenicareinparticulartwoextremelytoxicmetalsthatposeveryhighhealthrisks.Remediationmethodsthatallowfast,economicandeffectivetreatmentofwaterpollutedwithsuchcontaminantsishighlyneeded.Nanotechnologycanintroducenewmethodsforthetreatmentandpurificationofwaterfrompollutants,aswellasnewtechniquesforwastewatermanagementandwaterdesalinization.Nanomaterials currently investigated for remediation include iron and bimetallic nanoparticles, semiconductornanoparticles,magneticnanoparticlesanddendrimers.BelowaresomedetailedexamplesPage4of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 5. NANOYOUTeachersTrainingKitModule2Chapter2RemediationusingmetalnanoparticlesThe use of zerovalent (Fe0) iron nanoparticles for the remediation of contaminated groundwater and soil is agood example of how environmental remediation can be improved with nanotechnology. When exposed to air,ironoxidizeseasilytorust;however,whenitoxidizesaroundcontaminantssuchastrichloroethylene(TCE),carbontetrachloride, dioxins, or PCBs, these organic molecules are broken down into simple, far less toxic carboncompounds.Sinceironisnontoxicandisabundantinthenaturalenvironment(inrocks,soil,wateretc.),someindustrieshavestartedusinganironpowdertocleanuptheirnewindustrialwastes.However,theironpowder(that is, granular zerovalent iron with dimensions in the micron range) is not effective for decontaminating oldwastesthathavealreadysoakedintothesoilandwater.Moreover,bioremediationusinggranularironpowderisoften incomplete: some chlorinated compounds, such as PCE or TCE, are only partially treated and toxic byproducts (such as DCE) are still found after treatment. This effect is due to the low reactivity of iron powders.Anothermatterofconcernisthedecreaseofreactivityofironpowdersovertime,possiblyduetotheformationofpassivationlayersoverthesurfaceoftheirongranules.Nanotechnology has offered a solution to this remediation technology in the form of iron nanoparticles. Thesenanoparticlesare10to1000timesmorereactivethencommonlyusedironpowders1.Theyhavealargersurfaceareaavailableforreactingwiththeorganiccontaminantandtheirsmallsize(1100nm)allowthemtobemuchmoremobile,sotheycanbetransportedeffectivelybytheflowofgroundwater.Ananoparticlewaterslurrycanbeinjectedtothecontaminatedplumewheretreatmentisneeded(Figure1).Thenanoparticlesdonotchangebysoil acidity, temperature or nutrient levels, so they can remain in suspension maintaining their properties for Figure1.Nanoscaleironparticlesforinsitu remediation. Page5of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 6. NANOYOUTeachersTrainingKitModule2Chapter2extendedperiodsoftimetoestablishaninsitutreatmentzone.Experimentalresultscollectedbothinlaboratoryandinthefieldhaveshownthatnanoscaleironparticlesareveryeffective for the complete transformation and detoxification of a wide variety of common environmentalcontaminants,suchaschlorinatedorganicsolvents,organochlorinepesticides,andPCBs.Whennanosizedironpowdersareused,notoxicbyproductsareformed,aresultoftheincreasedreactivityandstability of the nanoparticles compared to the granular iron powder2. Contaminant levels around the injectionlevel is considerably reduced in a day or two and nearly eliminated within a few days. Thanks to their stability,nanoironparticlesremainactiveinasiteforsixtoeightweeksbeforetheybecomedispersedcompletelyinthegroundwaterandbecomelessconcentratedthannaturallyoccurringiron.Researchersareassessingwhetherthetechnique could also be used for the remediation of dense nonaqueous phase liquid (DNAPL) sources withinaquifers,aswellasfortheimmobilizationofheavymetalsandradionucleotides.Bimetallic iron nanoparticles, such as iron/palladium, have been shown to be even more active and stable thenzerovalentironnanoparticles,thereforefurtherimprovingthisremediationtechnology.Finally,ironorbimetallicnanoparticlescouldbeanchoredonsolidsupportssuchasactivatedcarbonorsilicafortheexsitutreatmentofcontaminatedwaterandindustrialwastes.RemediationusingsemiconductingnanoparticlesSemiconducting nanoparticles made of TiO2 and ZnO are used in photocatalytic remediation. Beingsemiconductors these materials produce an electronhole pair when irradiated witha light having energy intheorderofthematerialbandgap.TiO2hasabandgapof3.2eVsowhenthematerialisirradiatedwithUVlight(puthere the corresponding energy of UV) an electronhole pair is formed. Both TiO2 and ZnO are capable oftransferringthechargetoorganicpollutants(suchashalogenetaedhydrocarbons)andinducetheiroxidationtoless harmful byproducts, such as CO2, H2O and other species. The scheme of the overall process is shown inFigurekm.SinceTiO2 andZnOarereadilyavailableandinexpensivetheiruseforremediationhasbeenstudiedformanyyears.Recently,nanosizedTiO2 andZnOhavebeenconsideredasthesehavemoreactivesurfacegiventhesamevolumeofmaterial.Thevisionistocreatesomesolarphotocatalysisremediationsystems,whereTiO2orZnO are used to convert toxic contaminants, such as chlorinated detergents, into benign products using sunradiation. There is evidence that those semiconductors can photodegrade numerous toxic compounds, but thetechnologyrequiresimprovementsintermofefficiency,sinceTiO2orZnOonlyadsorbUVlightwhichrepresentsonly5%ofthesolarspectrum.Inthiscontext,nanotechnologycouldbringanimprovementintwoforms: Page6of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 7. NANOYOUTeachersTrainingKitModule2Chapter21. When noble metals like gold and platinum are chemisorbed to the TiO2 and ZnO nanoparticles thephotocatalyticactivityisaccelerated.Thereasonisthatthepresenceofthemetalhelpstokeeptheelectronsandholesfromrecombininginthesemiconductorandtherebyincreasetheefficiencyofthephotocatalysis.2. To increase the photoresponse window of TiO2 and ZnO from UV to visible light the nanoparticles can bemodifiedwithorganicorinorganicdyes.Thisisanareaofintensiveresearch.Nanomaterials have also been found able to remove metal contaminants from air. For instance silicatitaniananocompositesareinvestigatedfortheremovalofelementarymercury(Hg)fromvapourssuchasthosecomingfrom combustion sources. In these nanocomposites, silica acts as a support material and titania transformsmercurytoalessvolatileform(mercuryoxide).RemediationusingdendrimersDendrimers are highly branched polymers with controlled composition and nanoscale dimensions. Chelatingagentsintheformofdendrimersarealsostudiedfortheremovalofmetalcontaminants.Thesecanbedesignedsotoabletoactascages`andtrapmetalionsandzerovalentmetals,makingthemsolubleinappropriatemediaorable to bind to certain surfaces. The vision is to use dendrimers as nanoscale chelating agents for polymerssupportedultrafiltrationsystems.RemediationusingmagneticnanoparticlesAnother class of nanoparticles that have environmental applications is magnetic nanoparticles. For instance,researchersfromRiceUniversitysCentreforBiologicalandEnvironmentalNanotechnology(CBEN)haverecentlyshownthatnanoparticlesofrustcanbeusedtoremovearsenicfromwaterusingamagnet.Theconceptissimple:arsenic sticks to rust which, being essentially iron oxide tends to be magnetic so it can be removed from waterusing a magnet. Nanosized rust, about 10 nm in diameter, with its high surface area, was found to improveremovalefficiencywhilereducingtheamountofmaterialused.Comparedtoothertechniquescurrentlyusedtoremovearsenicfromcontaminatedwater,suchascentrifugesandfiltrationsystems,thisonehastheadvantageofbeing simple, and most importantly, not requiring electricity. This is very important, given that arseniccontaminatedsitesareoftenfoundinremoteareaswithlimitedaccesstopower.Magneticnanoparticlesmodifiedwithspecificfunctionalgroupsarealsousedforthedetectionofbacteriainwatersamples(Figure2).Arsenic and arsenate may be also precipitated using nanoscale zerovalent iron (Fe0) as indicated by recentstudies.TheremovalmechanisminthiscaseinvolvesthespontaneousadsorptionandcoprecipitationofarsenicwiththeoxidizedformsofFe0.Asalreadynoted,zerovalentironisextremelyreactivewhenitisnanosized,soitiscurrentlyconsideredasuitablecandidateforbothinsituandexsitugroundwatertreatment.Page7of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 8. NANOYOUTeachersTrainingKitModule2Chapter2ELSA TOPIC: Although research seems to show that remediation using iron oxide nanoparticles is effective,therearecurrentlysomeconcernsintheuseofnanoparticlesforsoilandwaterremediation.Theconcernsarerelatedtothefaithofthenanoparticlesoncetheyareinjectedintothecontaminatedsite,andthepossibilitytheymightbesomobiletodisperseoutsidethetargetedarea.Itisnotclearifsuchasituationwouldposeanenvironmentproblem such as interferencewith plantsor animals lifecycle. For these reasons themethod isnotyetapprovedandusedintheEU.Researchisunderwaytoclarifythoseissuesanddiscussionsaretakingplaceonpossiblestrictregulationneededforthisremediationtechnology.RemediationusingaerogelsandsolidabsorbentsThe problem of oil spills in seawater is of great concern and has detrimental environmental consequences.Currentlytherearenumerousbioremediationstrategiesthatusemicrobialcultures,enzymeadditivesornutrientadditives to clean up oil spills. The purpose of these additives is to boost the natural nanotechnology of themicrobialcommunitytodecomposeoilmaterial.Anothermethodthatisgainingacceptanceistheuseofaerogels(a nanomaterial) modified with hydrophobic molecules to enhance the interaction with the oil. These aerogelshaveverylargesurfaceareasotheycanadsorbsixteentimestheirweightofoil.Theyactasasponge:oncetheoilhas been absorbed, the oilsoaked sponge can be removed easily. The problem is that these materials areexpensivesoalternativesareunderstudy.AcompanycalledInterfaceScientificCorporationhasdevelopedanewnanomaterialmodifiedwithselfassembledmonolayers(SAMs)whichappearstobeveryeffectiveinremediatingoil spills. The company does not provide details of the material but claims that thenanomaterialcan absorb 40timesitsweightinoilamethodthatexceedsanycurrentmethodandthattheoilcanberecovered.As outlined before, the use of nanoparticles is very promising in the filed of environmental remediation andtreatment,preciselyfortheirsmallsizeandreactivity.Neverthelesssomeconcernexistsontheiruseinsoilandwatertreatment:oncedispersedinacontaminatedsite,wouldthenanoparticlesbemobiletoapointthattheycouldbeuptakebyplantsoranimalsatthesiteandadverselyaffectthem?Biodegradablenanoparticlesarelikelytobelessproblematic;neverthelessthereisaneedtoinvestigatethesesafetyaspects,andthisisthesubjectofnumerous international research programs. These concerns belong to the more general field of environmentalimpact assessment of the use of nanoparticles, which includes both risk assessments and lifecycle analysis tounderstandtheshorttermandlongtermsaffectsofnanoparticlesintheenvironment.Althoughimportant,theseaspectsarenotcoveredinthispaperbuttheinterestedreadercanfindsomeusefulreferencesattheendofthisdocument(underotherusefulBibliography). Page8of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 9. NANOYOUTeachersTrainingKitModule2Chapter2NanomembranesandnanofiltersNanotechnologycanalsobeemployedforthefabricationofnanofilters,nanoadsorbentsandnanomembraneswithspecificpropertiestobeusedfordecontaminatingwaterandair.Aswithotherapplications,itistheabilitytomanipulate matter at a molecular level that makes nanotechnology so promising in this field, together with thesmall size and high surfacetovolume ratio of nanomaterials that are employed for the fabrication of theseproducts.Figure2.Aceramicnanomembrane.PhotocourtesyofProfessorM.Wiesner,WiesnerLaboratory,DukeUniversity.Inprinciple,nanotrapsdesignedforacertaincontaminantcanbeproduced,forinstancehavingaspecificporesizeandsurfacereactivity.AnexampleisgivenbytheworkcarriedoutatRicesCBEN, where researchers are developing reactive iron oxideceramicmembranes(ferroxanemembranes)thatarecapableofremediatingorganicwasteinwater(Figure2).Filtersandmembranescanalsobeengineeredtobeactiveinthesenseofbeingcapablenotonlytotrapacertaincontaminant,butalsotochemicallyreactwithitandconvertittoanontoxicproduct.Forinstance,researchersatthe University of Tennessee are investigating a new type of nanofibre for the removal of microorganisms viafiltrationthatcanalsokillthemoncontact.An interesting application of nanomembranes has been developed by researchers form the University ofCalifornia Los Angeles (UCLA) in the form of a new reverse osmosis (RO) membrane for seawater desalinizationand wastewater remediation. The membrane is made of a uniquely crosslinked matrix of polymers andengineerednanoparticlesdesigntodrawinwaterionsbutrepelcontaminants.Thisispossibleduetothenanosizeoftheholesformingthemembranewhicharetunnelsaccessibleonlytothewatermolecules.Anotherdistinctivefeatureofthisnanomembraneisitsabilitytorepelorganicsandbacteria,thankstothechemicalcompositionofthenanoparticlesembeddedinthemembrane.ComparedwithconventionalROmembrane,theseonesarethuslesspronetoclogging,whichincreasesthemembranelifetimewithanobviouseconomicbenefit. Page9of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 10. NANOYOUTeachersTrainingKitModule2Chapter2PollutionPreventionNanotechnologies offer numerous innovative strategies to reduce the production of pollution during numerousprocesses. These include: reduction of waste in manufacturing processes; reduction in the use of harmfulchemicals;reductionintheemissionofgreenhouseeffectgasesduringfuelcombustions;useofbiodegradableplastics.Theseareonlyfewofthemanyapproachesthatcanbetakentoreducethepollutionoftheenvironment.Nanotechnologies are already actively involved in this sector, either as a technology to produce advancedmaterialsthatpolluteless,orasamethodtoincreasetheefficiencyofcertainindustrialprocesses(e.g.,catalyticprocess).MaterialsMaterials that are more environmentfriendly fabricated using nanotechnologies include biodegradable plasticsmadeofpolymersthathaveamolecularstructureoptimalfordegradation;nontoxicnanocrystallinecompositematerialstoreplacelithiumgraphiteelectrodesinrechargeablebatteries;andselfcleaningglasses,suchasActivGlass,acommercialproductavailableworldwidefromPilkington.TheglassiscomposedofaspecialcoatingmadeofnanocrystalsofTiO2which,onceexposedtodaylight,reactsintwoways.First,itbreaksdownanyorganicdirtdeposits on the glass and second, when exposed to water, it allows rain to sheet down the glass easily andwashes the loosened dirt away. In this product TiO2 is found in the form of a thin film in the range of 220 nmdeposited by a hightemperature gas phase. The thickness of the film is essential for ensuring maximumphotocatalyticactivityandtransparency(Figure3).Figure3.ExplanationonhowthePilkingtonActivSelfCleaningGlassworksasdescribedbythemanufacture(www.pilkington.com). Page10of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 11. NANOYOUTeachersTrainingKitModule2Chapter2Thecoatingishydrophilic(watercontactangle(CA)is20comparedtoconventionalsodaglassforwhichCAis40).Upondirtdeposition,thecontactangleofthesurfaceincreases,butisthenreducedagainuponirradiation.Thephotochemicalreaction,whichrequiresoxygen,isquitecomplexandinvolvesanumberofradicalsubproducts.Titaniumoxideisnotconsumedinthereactionbutactsasacatalyst.Asaresult,organicmaterialisdecomposedtoCO2.Concurrently,thecontactangleofthesurfaceisfurtherreduceduponirradiation(from20toabout15).After irradiation, dirt can be more easily removed from the glass by rain. The result is that water spreads veryeffectively(formingalayerovertheglass),washingthesurfaceeasily.Thecoatingispartiallydurabletoabrasion.Although the name of the product suggests otherwise, this is not a truly selfcleaning layer since it requireswatertoallowthesurfacetobecleaned.LotuseffectsurfacesandtextilesAttimesthetermselfcleaningisalsoassociatedtosurfacesthathavebeenengineeredsotoimitatethenaturalselfcleaningeffectfoundinsomeleaves,suchastheLotusleaf(theeffectisdescribedindetailsinChapter2ofModule 1 Natural Nanomaterials). In this case, the coating is not a uniform layer with a specific chemicalfunctionality(likeinthecaseofphotocatalyticcoating),butitisasurfacewithanengineeredtopographyatthenanoscalelevel.Thisleadstoasurfacewhichissuperhydrophobic(extremelywaterrepellent).Waterdropletsrolloffthesurfaceandindoingsocollectandremovedirtdepositedonthesurface.The Lotus effect has been an inspiration for several innovative materials, such as coatings and textiles. Therealization that certain surface properties can induce water repellence is important in numerous applications.Materialscientistsarenowengineeringnumeroustypesofmaterialstorenderthemsuperhydrophobic.Therearemanyinstanceswhereavoidingthewettingofasurfaceisanadvantage,forinstanceintextiles,whichareroutinelystainedbyliquids(juices,coffeeetc)andsolids(mustard, ketchup etc). Some companies such as NanoTex are now commercializingtextiles that are engineered to confer superhydrophobic properties to their textiles(Figure4andFigure5).Thiseffectisobtainedbythepresenceofnanosizedwhiskersonthesurfaceofthefibresthatcomposethefabric.Figure4.LiquidstainingonaNanoTex fabric. (Image credit: imagecourtesy of NanoTex, Inc., CopyrightNanoTex.Inc) Page11of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 12. NANOYOUTeachersTrainingKitModule2Chapter2 NANOTEXLOTUS Figure5.HighresolutionimagesoftheNanoTexfabric(ImagescourtesyofNanoTex,Inc.,CopyrightNanoTex.Inc).(Right):contactangleimagesofwaterdropletsonNanoTexfabricandLotusleaf(Images:iNANO;AarhusUniversity,CreativeCommonsAttributionShareAlike3.0). ExperimentDintheExperimentModuledealswithstudyingtheLotuseffectandlearninghow materialscanbeengineeredtomimicthiseffect. The inclusion of TiO2 nanoparticles in textiles is also investigated, as this material catalysis the degradation oforganicdirt.Surfaces and materials engineered to mimic the Lotus effect are useful in construction as they allow reducingcleaning.Currentlytherearevariousproductscommercializedorunderresearchthatmakeuseofthisprinciple,forinstanceLotusan,anexteriorpaintfromthefirmStolaunchedin1999.Theapplicationofthisexteriorpaintreducestheattackofdirttothefaadeitisappliedto,andinducesselfcleaningpropertieswhenraindropletsrolloffanddragdirtawaywiththem.The above mentioned applications are an example of cases where the superhydrophobic properties of anengineered material, such as a textile or a coating, can reduce the cleaning it needs, with a reduction of waterusageandobviousenvironmentbenefit.It should be noted that, differently from photocatalytic coatings, those based on the LotusEffect are nontransparent: light is scattered due to the rough nature of the coating. Researchers are thus also investigatingtransparentsuperhydrophobicsurfaces Page12of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 13. NANOYOUTeachersTrainingKitModule2Chapter2Antimicrobialcoatings,textilesandotherproductsAntimicrobialcoatingsareneededinmanyapplications,forinstancetoprotectmedicalsurfacesandtools,ortoreduceantimicrobialattackinthehullofboats.Spaysandcoatingsforthisaimexistalreadybutimprovementinthisareaisneededasmanymicrobesarebecomingresistanttotheantibiotictreatmentsthathavebeenusedsofar.Topreventbacteriaattachmentsurfaceswithnanocoatingwithspecificfunctionalitiesandtopographiesareunderinvestigation.Ananomaterialthatisbecomingwidelyusedissilvernanoparticles.Silverisametalthathasalonghistoryofbeingusedforitsantibacterialproperties:peoplehaveknownabouttheantibacterialpropertiesofsilverforcenturieseventheRomansusedittodresswounds.Thispropertyexplainswhy silver has been use to produce the highestquality cutlery (silvareware) or to store water in vessels inancienttime(evenbythePhoenicians).Inmedicine,silvernitrate1%wasusedinthepastasaneyesolutiontopreventinfectionsinnewborns,anduntilantibioticswherenotdiscovered,silvernitratewasaddedtogermicides,antisepticsasadisinfectant.The antibacterial properties of silver are due to the silver ions (Ag+) released by the bulk metal once this isoxidised.Infactsilvertablewareordishwarehasantimicrobialactivityonlyifoxidizedspeciesarepresentontheirsurface. Silver ions induce the oxidative stress of the bacteria cell wall, where many cellular functions areperformed,affectingthebacteriasabilitytorespireandtomaintainanintracellularenvironmentsuitableforlife.Silver ions inhibit bacteria growth, suppress respiration and metabolism and basically induce cell death. Silvertoxicity has been shown towards many strains of bacteria, both gram negative and gram positive, and to fungi(lesstowardsviruses).Silverinisnotconsideredtoxictothecardiovascular,nervousorreproductivesystemsinhumans.Theexposuretosilverinsomepeopleleadstoargyria(orargyrosis)whichisduetoaprocessofsequestrationofsilverionsinaninnocuousformwhichisnotreversible,andleadstopigmentationordiscolourationofskin.Thefewcasesofdeathduetosilverintoxicationwererelatedtoveryhighconcentrationsofsilver.Inrecentyearssilvernanoparticles(oftencallednanosilver)havebeenaddedtonumerousconsumerproductsto infer them antimicrobial properties. Because of their antibacterial effectiveness and low toxicity towardsmammalian cells silver nanoparticles have become one of the most common nanomaterials used in consumerproducts.Therangeofproductsisquitewideandincludeskitchenutensils(pots,pansetc.),personalwear(socks,shoe liners, underwear), outwear and sportswear, bedding items (sheets and mattress covers), appliances(refrigerators,washingmachines,airfiltrationdevices,computerkeyboards),spraystodisinfect(deodorants)andcosmetics. Nanosilver is incorporated into these different materials through various impregnation techniques(sprayed,paintedovertheproduct,incorporatedintoplasticsetc.) Page13of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 14. NANOYOUTeachersTrainingKitModule2Chapter2ELSATOPIC:Silverhasbeenusedforcenturiessoexposureofsilver,itsionsandassociatedformsisnotnewtohumans,animalsandplants.Thereisgrowingconcernthoughthatthesteadyincreaseinconsumerproductsusingnanosilvermightleadtodetrimentalenvironmentalconsequences.Theconcernistwofold,andinvolvesthe possible release of silver nanoparticles from the product and that of silver ions (and colloids formed withother salts) either though use of the material (e.g., washing of fabrics containing nanosilver), or after theirdisposal.Currentlyitisnotclearwhatismostdangerousfortheenvironment:theactualsilvernanoparticlesorthe ions they release. Since it is known that nanomaterials are normally more reactive than their bulkcounterpart,andthattheycandisplaynewproperties,thereisconcernthatsilvernanoparticlescouldbehaveunexpectedlytowardscells(human,bacteria,virus,plantcellsetc.).Questionsareraisedalsoconcerningsilvernanoparticleuptakebyplantandothersystemsthatmightcomeincontactwithnanosilverwellbeforehumansthroughwastewaterorotherwatersystems.Inmodelexperimentsitwasshownthatsilvernanoparticlesareverytoxictobenignbacteriausedtoremoveammoniainwastewater.Theconcernisthatiflargeamountsofconsumable products (like socks, toothbrushes, jackets etc.) are used, large amounts of silver ions, silvernanoparticlesortheiraggregateformscouldbereleasedinriversandlakesanddamagetheecosystem.Manyagenciesarecallingforstrictersafetytestingofnanobasedproductsandforresearchonthesafetyoftheseproducts.NANOYOUDILEMMATheexampleofsilvernanoparticlesinaconsumerproduct(socks)isoneoftheNANOYOUdilemmaincludedintheNANOYOURolePlayCardGame(seewww.nanoyou.eu/en/decide).Inthisdilemmastudentsconsiderthecaseofsockshavingsilvernanoparticlesintheirfabrictoeliminatethebacteriawhichcausesmellyfeetandfungalinfections.Basedonthefactthatuncertainlyexistsregardingtheecotoxicityofnanosilver,studentsareencouragedtoreflectonthisproductthroughabenefitvs.riskanalysis.Thedilemmais:Isitrighttosellantibacterialsockscontainingsilvernanoparticleswhileitisnotknownyetifthereareentirelysafefortheenvironment? Page14of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 15. NANOYOUTeachersTrainingKitModule2Chapter2FertilizersandwoodtreatmentproductsAnother area where nanotechnologies are making a contribution is the development of fertilizers and woodtreatment products that are more stable and leach less into the environment. For instance, researchers at theMichigan State University have incorporated biocides for wood treatment inside polymeric nanoparticles. Theirsmallsizeallowsthemtoefficientlytravelinsidetheveryfine,sievelikestructureofwood.Atthesametime,thebiocide,beingsafelytrappedinsideananoshell,isprotectedfromleachandrandomdegradativeprocesses.BiomimeticwaterharvestingInModule1itwasshownhownaturalnanomaterialsareinspirationalforthefabricationofadvancedmaterials(Chapter2andChapter5inModule1).Oneexampleisbiomimeticwaterharvestingmaterials.Someplantsandinsectshavetheabilitytocapturewaterfromfog.ForinstancetheNamibiandesertdwellingbeetleStenocarahasbumpsonitswingsscaleswithsuperhydrophobicnanostructuredsurfaces.Thepeaksofthebumpsareextremelyhydrophilic, whereas the slops of the bumps and the area between them are covered with hydrophobic wax.Thankstothisfinenanostructure,asdropletsaccumulateinsize,theyrollfromthetopstothewaxychannelstoaplace in the beetles back that supplies its mouth. A company called QinetiQ, LtD from UK has developed somesheetsthatcapturewatervapoursfromcoolingtowersandindustrialcondensersbasedonthenanostructureofthebeetlewing.Thesematerialscancapture10timesmorewaterthanconventionaltechnology.NanocatalysisA catalyst is a substance that increases a chemical reaction rate without being consumed or chemically altered.Conventionalcatalystsarerareearthmetalssuchaspalladium(Pd)andplatinum(Pt),whichareveryexpensive.Oneofthemostimportantpropertiesofacatalystisitsactivesurfacewherethereactiontakesplace.Theactivesurfaceincreaseswhenthesizeofthecatalystsisdecreased(Figure6).Thehigheristhecatalystsactivesurface,thegreateristhereactionefficiency.Also,researchhasshownthatthespatialorganizationoftheactivesitesinacatalyst is important as well. Both properties (nanoparticle size and molecular structure/distribution) can becontrolled using nanotechnology. Thus one area of intense nanoscience research is the development of newnanostructuredcatalyticsurfaces.Intheenvironmentalfield,nanocatalysisisbeinginvestigatedforinstancefordesulphurizingfuels,withtheaimofdevelopingcleanfuelscontainingverylowsulphurproducts(producedinthefuelduringitsrefiningprocessandresponsible for generating sulphuric acid upon fuel combustion). Recent nanotechnology research performed atiNANO has also aided the Danish company Haldor Topse A/S in implementing a new generation ofhydrodesulphurizationcatalysts(BRIMTechnologies)tobeusedforsulphurcleanupoffossilfuelsworldwide.Thehydrodesulphurization(HDS)catalyticreactionisareductivehydrogentreatmentoffuelstocleanupsulphurPage15of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 16. NANOYOUTeachersTrainingKitModule2Chapter2containing oil compounds and thereby save our environment for many tons of harmful sulphur emissions on adailybasis. Figure 6. (Left) Overview of the hydrodesulphurization (HDS) catalytic reaction. (Right). Schematicrepresentationshowinghownanoparticlescouldbeincludedinthecatalystmaterialofadesulphurizingfuelreactor.TheimageonthefarrightisarealScanningTunnellingMicroscope(STM)imageofaMoS2nanocrystalon Au(111) showing peculiar atomic distribution at the edges of the crystal. (Image credit: courtesy of F.Besenbacher,iNANO,AarhusUniversity).Another example is Oxonicas Envirox fuel which uses nanosized cerium oxide as a catalyst to enhance theefficiencyofthefuelcombustion.Thisenhancedfuelhasbeentestedin2003and2004in1,000busesintheUK(another500busesweretrackedascontrol).Itwasfoundthatthetestbusesused5%lessfuelthenthecontrolsandthatthefuelsavingsmorethenpaidfortheadditive.Nanoscale catalysts are also promising for improving air quality and for treating particularly challengingcontaminantsinwaterthatmustbereducedtoaverylowlevel. Page16of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 17. NANOYOUTeachersTrainingKitModule2Chapter2CatalyticgoldAsabulkmaterialgoldisnotableinert,itdoesnotreactwithmanychemicals(includingstrongacidsandbases).However, when in a nanosize form, gold becomes extremely reactive and this has opened the opportunity ofusingitincatalyticprocesses.ConventionalmaterialsusedincatalysisarerareearthmaterialssuchasPtandPd,which are extremely expensive. Alternatives are highly needed. Nanogold has been shown to be an extremelyefficientcatalystinnumerouspollutioncontrolstudies.ForexampleithasbeenshownthatitisabletoremoveCOfromroomairunderambientconditionsandfromfuelcellhydrogenfeedgas.AnotherstudyhasshownthataAuPt cocatalyst was able to brake down TCE 100 times faster than did a catalyst made of a traditional material.Recently the company Nanostellar Inc. has announced an engineered nanogold oxidation catalyst which canreducedieselhydrocarbonemission40%timesmorethancommerciallyavailablematerials.Consideringthatthereare over 14 million lightduty diesel vehicles worldwide, and 2 million heavyduty one, the impact of thisnanotechnologycouldbeenormous.RecoveryofcatalyticmaterialOneoftheproblemsassociatedwithcatalysisisthatitoftenmakesuseofrareearth materials such as palladium (Pd). Natural Pd resources arelimited so there is a need to recycle industrial waste coming fromprocessesthathaveusedPdasacatalyst.RecyclingPdrequiresreductionof Pd(II) to Pd(0).As anenvironmentally friendly alternative to chemicalrecyclingprocesses,iNANOisinvestigatingtheuseofbacteriatomediatePdreduction.Theenzymehydrogenasefoundinthemembraneofmanybacteria holds the potential to transfer electrons from an organicsubstratetoPd(II).Inthepresenceofsomebacteria,thePdisproducedasnanoparticleslocatedonthecellsurfaceandintheperiplasmicspaceof Gram negative bacteria (denominated bioPd). Figure 7 shows anexample.ThecatalyticpropertiesofthebioFigure7.AnSEMimageofDesulfovibriodesulfuricans,aPd are similar to commercially available PdGramnegativebacteriumafterPdrecycling.Pdisproducedasnanoparticles.The hope is to use bacteria tonanoparticles(blackparticlesintheimage)locatedonthecellrecovercatalyticallyactivePdfromindustrialsurfaceandintheperiplasmicspaceofthebacterium.(Imagewaste, and the recovered Pd be used forcourtesyofRikkeLousieMyer,iNANO.CopyrightiNANO).othercatalyticprocesses. Page17of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 18. NANOYOUTeachersTrainingKitModule2Chapter2GreenmanufacturingManufacturing processes are always accompanied by the production of diverse waste products, many of whichpose a threat to the environment and thus need to be removed and treated. Ideally, manufacturing processesshouldbedesignedtominimizematerialusageandwasteproduction,whileensuringtheuseoftheleastamountofenergypossible.Greenmanufacturingisagenericnametobroadlycovermethodsandtechnologiesthataredirectedtowardsachievingthisgoal.Itincludesthedevelopmentofnewchemicalandindustrialprocedures(forinstance waterbased rather the solventbased processes); reduction in the use of unsafe compounds (such asmetals);developmentofgreenchemicalsthataremoreenvironmentcompatible;andefficientuseofenergy.Intermsofitsapplicationtothereductionofmanufacturingwaste,nanotechnologycancontributeintwoways:bydirecting the manufacturing to be more controlled and efficient, and by using nanomaterials (such as catalysts)that can raise the manufacturing efficiency while reducing or eliminating the use of toxic materials. Overall,nanotechnology has the potential of making industrial processes more efficient in terms of energy usage andmaterialusage,whileminimizingtheproductionoftoxicwastes.Sometimestheapplicationofnanotechnologytomanufacturingprocessesthatare`greener`isreferredtoasgreennanotechnology19;theseincludeforinstance:bottomup,atomiclevelsynthesisfordevelopingimprovedcatalysts;insertinginformationintomoleculestobuildnewmaterials(suchasDNA)throughhighlyspecificsyntheticroutes;scalingdownmaterialusageduringchemicalreactionbyusingnanoscalereactors;andimprovingmanufacturingtorequirelessenergyandlesstoxicmaterials.An example of green nanotechnology is the development of aqueousbased microemulsions to be used inalternativetovolatileorganiccompounds(VOCs)inthecleaningindustry.Thesetoxicandpotentiallycarcinogeniccompounds,suchaschloroform,hexane,percholoroethylene,areconventionallyusedinthecleaningindustry(likethe textile industry) as well as in the oil extraction industry. Microemulsions contain nanosized aggregates thatcanbeusedasreceptorsforextractingspecificmoleculesatananoscalelevel.ResearchersfromtheUniversityofOklahoma have synthesized microemulsions having waterattractive and waterrepellent linkers insertedbetweentheheadandtailpartsofasurfactantmolecule20.Theresultisasurfactantthathasaverylowinterfacialtension with a wide range of oils. When tested for cleaning textiles from motor oil residues, as well as forextracting edible oil from oilseeds, the microemulsions were found to be very competitive with conventionallyusedVOCs,bothintermsofextractionyieldandsimplicityoftheprocess. Page18of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 19. NANOYOUTeachersTrainingKitModule2Chapter2EnvironmentSensingProtectionofthehumanhealthandoftheenvironmentrequirestherapid,sensitivedetectionofpollutantsandpathogens with molecularprecision. Accurate sensors are needed for in situ detection, as miniaturized portabledevices, and as remote sensors, for the realtime monitoring of large areas in the field. Generally speaking, asensorisadevicebuilttodetectaspecificbiologicalorchemicalcompound,usuallyproducingadigitalelectronicsignalupondetection.Sensorsarenowusedfortheidentificationoftoxicchemicalcompoundsatultralowlevels(ppm and ppb) in industrial products, chemical substances, water, air and soil samples, or in biological systems.Nanotechnologies can improve current sensing technology in various ways. First, by using nanomaterials withspecificchemicalandbiologicalproperties,thesensorselectivitycanbeimproved,thusallowingisolatingaspecificchemicalorbiologicalcompoundwithlittleinterference.Hence,theaccuracyofthesensorsisimproved.Aswithother nanoengineered products discussed in this document, the high surfacetovolume ratio of nanomaterialsincreasesthesurfaceareaavailablefordetection,whichinturnhasapositiveeffectonthelimitofdetectionofthesensor,thereforeimprovingthesensitivityofthedevice.Nanosensorsaregenerallyfaster,astheycandetectthetargetedanalyte(e.g.,bacteria)atalowerconcentrationthataconventionalsensor,sothepositiveresponsearrives quicker. Scaling down using nanomaterials allows packing more detection sites in the same device, thusallowingthedetectionofmultipleanalytes.Thisscalingdowncapability,togetherwiththehighspecificityofthedetectionsitesobtainableusingnanotechnology,willallowthefabricationofsupersmallmultiplexsensors,thiswayloweringthecostoftheanalysisandreducethenumberofdevicesneededtoperformtheanalysiswithaneconomic benefit. Advancements in the field of nanoelectronics will also allow the fabrication of nanosensorscapableofcontinuous,realtimemonitoring.Research in the field of nanosensors includes various areas, like synthesizing new nanomaterials with specificdetectionsitesabletorecognizeacertainpollutant;developingnewdetectionmethods,toincreasethelimitofdetection of the sensors while ensuring a readable electrical signal; and miniaturizing the size of the sensorelementswhileintegratingthesewithlargerpartsofthedevice.AnexampleofhownanosciencecanbeappliedtothesensingtechnologyisshowninFigure8,whichschematizestheoperationalprincipleofaheavymetalnanosensordevelopedformonitoringheavymetalsindrinkingwater.Thesensorismadeofanarrayofelectrodepairsfabricatedonasiliconchipandseparatedbyfewnanometres.Whentheelectrodesareexposedtoasolutionofwatercontainingmetalions,thesedepositinsidethenanogapin between the electrodes. Once the deposited metal bridges the gap a jump in conductance between theelectrodes is registered. The size of the gap, being only few nanometres, allows the detection of a very lowconcentrationofmetalions.Thistypeofsensoriscallednanocontactsensor Page19of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 20. NANOYOUTeachersTrainingKitModule2Chapter2Figure 8. Schematic of a nanocontactsensor. (A) A drop of sample solutioncontaining metal ions is placed onto apair of nanoelectrodes separated withan atomic scale gap on a silicon chip.(B) Holding the nanoelectrodes at anegative potential, electrochemicaldeposition of a single or a few metal atoms into the gap can form ananocontact between the twonanoelectrodesandresultinaquantum jumpintheconductance.(Imagecredit:adapted from: Proceedings of Nanotechnology and Environment:Applications and Implications, ProgressReview Workshop III (October 2005), pg.67).NanowiresandnanotubesbasedsensorsSomenanomaterialsintheformofnanowiresornanotubesofferoutstandingopportunitiesassensorelementsinchemicalandbiologicalsensors.Individualsinglewalledcarbonnanotubes(SWNTs)havebeendemonstratedtoexhibitafasterresponseandasubstantiallyhighersensitivityforinstancetowardsgaseousmolecules(suchasNO2and NH3) than that of existing solidstate sensors. In this case, direct binding of the gaseous molecule to thesurface of the SWNT is the mechanism involved in sensing, upon which the electrical resistance of the SWNTdramatically increases or decreases. Moreover, this sensitivity was registered at room temperature, whereasconventionalsolidstatesensorsoperateatveryhigh(200to600C)temperaturesinordertoachieveenhancedchemicalreactivitybetweenmoleculesandthesensormaterial.AlthoughSWNTsarepromisingcandidatesasnanosensors,theyalsohavesomelimitationsthatcouldlimittheirdevelopment. First, existing synthetic methods produce a mixture of metallic and semiconducting NTs, only thelatterbeingusefulassensors.Second,inordertobeabletosenseavarietyofchemicalandbiologicalspecies,thesurface of NTs needs to be modified to have specific functionalities to bind those species. Flexible methods tomodifythesurfaceofNTstobindalargevarietyofanalytesarenotwellestablishedyet.Conversely,nanowiresofsemiconductorssuchasSidonthavetheselimitations:theyarealwayssemiconductorsandthereisestablished Page20of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433 21. NANOYOUTeachersTrainingKitModule2Chapter2knowledgeforthechemicalmodificationoftheirsurface.Borondopedsiliconnanowires(SiNWs)havebeenusedforthesensitiverealtimeelectricaldetectionofproteins,antibodiesthemetabolicindicatorcalciumandglucoseinwater.Thesmallsizeandthecapabilityofthesesemiconductornanowirestodetectinrealtimeawiderangeofanalytescouldbeusedfordevelopingsensorsfordetectingpathogens,chemicalandbiologicalagentsinwater,airandfood.CantileversensorsA cantilever sensor is a device made of an array of silicon cantilevers, each coated with a nanolayer which issensitive to a specific pollutant. The cantilevers are typically 10500 m long, but have a thickness of a fewmicrometres or less. The pollutantspecific layer on top of the cantilever arm is in the nanoscale regime. Theinteractionofthepollutantwiththearmofthecantilevercausesthistobendasaconsequenceofachangeinsurfacestress.Alaserbeamdetectsthisminutebending,whichcanalsoleadtoquantitativemassmeasurementofthe pollutant detected. Cantilever sensors have been developed to detect VOCs, heavy metals, pesticides andharmfulbacterialikesalmonella. Figure9.Schematicdiagramofacantileverbasedbiosensor.Theyellow moleculesbindspecificallytotheredmoleculesontherighthand cantileverandaredetectedbythebendingofthecantileve.(Image courtesyofM.Lorentzen(iNANO,UniversityofAarhus).Copyright Lorentzen). NOTEThisdocumenthasbeencreatedinthecontextoftheNANOYOUproject (WP4Task4.1).Allinformationisprovidedasisandnoguaranteeorwarrantyisgiventhattheinformationisfitforanyparticularpurpose.Theuser thereof uses the information at its sole risk and liability. The document reflects solely the views of itsauthors. The European Commission is not liable for any use that may be made of the information contained Page21of21TheresearchleadingtotheseresultshasreceivedfundingfromtheEuropeanCommunitysSeventhFrameworkProgramme (FP7/20072013)undergrantagreementn233433