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1、teinnanowiresmorequickly,moreeffi-ciently,andatlowercost.Theyhavealreadysucceededinmakingthewell-knownlabmicrobeEscherichiacoliintoaproteinnanowirefactorybysplicingintherequisiteGeobactergenes.Suchadevelopmentwouldremoveoneofthebottlenecksopeninguprapiddevelopmentofthetechnology,allowingthemtomasspr
2、oducetheproteinnanowiresthroughfermentationusingestablishedE.colitechnology.DavidBradley1369-7021hnpsdoi.org10.1016.mattod.2020.03.014Woody approach to recycling concreteForallitsincrediblydiversearrayofuses,concreteisaproblematicmaterialwhenitcomestodisposalattheendofusefullifeofabuildingorotherstr
3、ucture.However,theadditionofwoodfibersduringitsrecyclingmightgiveanewleaseoflifetowastematerialfromdemolishedbuildingsandcivilengineeringstructuresincludingbridges,accordingtoresearchfromTheUniversityofTokyo.TheteamattheUniversitysInstituteofIndustrialSciencehasdemonstratedthatwiththeappropriateprop
4、ortionsofwasteconcreteanddiscardedwooditispossibletomakeanewmaterialwithabendingstrengthsuperiortothatoftheoriginalconcrete.Giventheinitialenvironmentalcostsofmanufacturingcementandmakingconcrete,methodsofrecyclingwasteconcreteareanimportantpartofanyplansforconstructionsustainability.Concretehasbeen
5、usedinconstructionfordecades,itbuildsbridgesandreachesforthesky.Itsproductionusesconsiderableamountsofenergyandgenerateslargevolumesofcarbondioxide.Therehavebeeneffortstogreenwtheproductionprocesswithvaryingdegreesofsuccess.Ofcourse,concretehastwomaincomponents-aggregate,whichiscommonlygravelandcrus
6、hedstone,sand,andthecementthatbindsitalltogetherandallowsthemixturetobepouredintomouldsoronsurfacesafterwhichithardensintothetoughstructuralmaterialswithwhichtheworldisveryfamiliar.1.iLiang,firstauthorofnewworkreportedbytheteamatTheSixthInternationalConferenceonConstructionMaterials(ConMat20),points
7、outthatsimplyreusingaggregatefromoldconcretedoesnotimprovesustainabilityasitistheproductionofnewcementthatisdrivingclimatechangeemissions.Evenreusingtheaggregatewillrequirenewcement.Anew,environmentallyfriendlyapproachisnowneededtoclosethecircleonconcreteeconomics.Theresearchershavenowoptimizedtheir
8、methodbyadjustingthemixtureproportion,pressure,temperature,pressingduration,andwatercontenttomakeanewtypeofconcrete.Rigiditycomesfromhighlycross-linkedorganicpolymersinwood,ligninasitfiIlsthegapsintheconcreteandfunctionsasabindingagentwhenwasteconcretepowderisheated.uMostoftherecycledproductswemadee
9、xhibitedbetterbendingstrengththanthatofordinaryconcrete,addsseniorauthorYuyaSakai.Thesefindingscanpromoteamovetowardagreener,moreeconomicalconstructionindustrythatnotonlyreducesthestoresofwasteconcreteandwood,butalsohelpsaddresstheissueofclimatechange.*Thenewmaterialhasanotherputativeadvantageoverco
10、nventionalrecycledconcrete-itcouldbebiodegradable,atleastinthesensethatbio-degradingagentsmightultimatelybeusedtobreakdownthewood-containingmaterials,whichmightthenfindanotheruse.Theteamsuggeststhattheirmethodmightbeextendedtousingotherdiscardedplantmatter,ratherthanwood,tooptimizethepropertiesforot
11、herdifferentapplications.DavidBradley13697021httprdoi.og10.1016j.mattod.2020.03.013BetweenthesheetsTwo-dimensionalmaterialsremainahottopicandfindingwaystomakethemfromlayeredvanderWaalscrystalscouldopenupnewapplicationsinelectronics,optoelectronics,andquantumdevices.Now,researchersColumbiaUniversity,
12、NewYork,haveusedultra-flatgoldtapetoexfoliatevdWsinglecrystalslayerbylayerintonewmonolayers.Theobtainyieldsclosetounityandthesizeoftheir2Dlayersarelimitedonlybythedimensionsoftheoriginalbulkcrystal;uptothecentimeterscale.TheresearchersreportthatwMuIti-Iayerscouldbereassembledtoartificialstructures,s
13、uchasaMoSe2WSe2singlecrystalbilayerwithatwistanglechosentoquenchintralayerexcitonformation.Liuetal.,Science(2020)367,6480:903;Doi:https:/doi.Org/10.1126/science.aba1416.Theapproachisreminiscentoftheoriginalstickytapeexperimentsthatledtothefirstproductionofgraphene,madebypeelingoffamonolayerfromapenc
14、ilmarkonaglassslide.Theareaspossiblewiththisnewlyreportedgoldtapeexfoliationare,however,approximatelyamilliontimeslarger.Theteamexplainsthattheycanassemblethemonolayersintomacroscopicartificialstructures.Thesestructuresareinaccessiblethroughconventionalbulkcrystalgrowth.Forinstance,theycanproducelay
15、ersofmolybdenumdisulfidethatarealignedwitheachother.Theresultingstackslackmirrorsymmetryandsodemonstratestronglynonlinearopticalresponses.Inthatparticularexample,thematerialabsorbsredlightandemitsultravioletlightthroughsecond-harmonicgeneration.ThisapproachtakesUSonestepclosertomassproductionofmacro
16、scopicmono-layersandbulk-likeartilicialmaterialswithcontrollableproperties/explainsoneoftheprincipalinvestigatorsonthework,JamesHone.Theworkrepresentsanewwaytoscaleuptheproductionof2DmaterialsthathasnotbeenpossiblewithconventionalapproachessofarwherethinfiImgrowthhasvariouslimitationsintermsofmaterialquality,reproducibility,andtherequirementforhightemperatures.Otherteamshaveusedgoldtoexfoliatelarge2
