聽力5材料科學(xué)對話

WhatisthemainpurposeoftheTodescribesomeproblemsassociatedwithToexplainwhynewmaterialsareneededformakingTodescribepropertiesofarecentlydevelopedTodescribeexperimentsthatmeasuredthestrengthofWhatsimilaritybetweengrapheneanddiamonddoestheprofessorBothhaveasimpleatomicBothareextremelyBotharepoorerheatconductorsthanBothhavenaturalandsyntheticWhydoestheprofessormentionadhesiveTogiveanexampleofapotentialapplicationforToexplainhowthefirstsampleofgraphenewasTosuggestthatnanomaterialsaresometimesfoundinunexpectedTomakeapointabouttheflexibilityofWhatdoestheprofessorimplyaboutItcannotbereplacedbyasyntheticItcanbeusedincombinationwithItsconductivityissimilartoItsusefulnessfornewelectronicsisAccordingtotheprofessor,whatgraphenecanbeusedcommercially?

mustresearcherssolveClickon2HowtoattachgraphenetoexistingHowtomass-producelargesheetsofHowtoregulategraphene’selectricalHowtopreventgraphenefromstickingtoWhydoestheprofessorsayTosuggestthatthescientistslackedToexplainscientists’surpriseaboutgraphene’sToemphasizethedifficultyofsuchaToencouragestudentstooffertheirf水WhyisthewomanhavingaproblematthecomputerShecannotfindupdatedprintinginstructionsThecomputersheisusingisnotconnectedtoaSheisnotawareofthenewlimitonSheisnotawareofthechangeintheprocessforprintingHowdoesthecomputerlab’snewproceduresaveItrequiresapprovalfortheprintingofsacertainItrewardsstudentsforusingrecycledItpreventsstudentsfrom sItallowsstudentstoprint sthatareclassWhyisthewomaninterestedinaninternshipattheShehopesitwillleadtoapermanentjobShewantstobroadenherSheisconsideringchanginghermajorcourseofstudytoSheneedstofulfillarequirementforWhatcanbeinferredfromthespeakers’discussionoftheman’sThewomanknowsthefriendfromoneofherengineeringThewomanhopesthefriendcanhelphergettheThefriendwouldnotadvisethewomantoworkattheThefriendstartedtheyouthprogramattheWhatbenefitsofagreenroofdoesthewomanClickon2ItcanhelpdecreaseenergyItcollectsrainwatertosupplementthebuilding’swaterItprovidesresearchopportunitiesforItreduceswaterpollutionintheA:B:ConsultantintheComputerA:Couldyoucheckthesettingsonthiscomputer?B:Sure.What’swrong?A:I’veclickedprintlikefourtimes,butnothingisB:Oh,thiswillbeaneasyfix.Todaymustbethefirsttimeyouhavebeeninthecomputerlabthismonth,ah?A:B:.Well,onthefirstofthismonthwestartedsomethingnew.Ok,soyoualreadyknowhowtosendsomethingtotheprinter.A:Right.ThatiswhatIB:Soafterthat,weaddedanewstep;printingstations.A:Whatarethose?B:Thereisastation,well,acomputeractuallynexttoeveryprinternow.You’llneedtogototheprintingstationandyou’llseealistofall sthatpeoplehavesenttotheprinter.Findonthelist,clickonA:B:(Inaudible)mistake,soweendupwaistingalotofpaper.Wearehothatwiththisnewsystemthiswon’thappenasmuch.Somebodymightclickprintbymistake,buttheyarenotgonnagetupandwalktotheprintingstationbymistaketoo.A:Isee,B:Noproblem.You’llalsoseeyourprintingallotmentatthestation,soyou’llknowhowmanypagesyouhaveleftthisforthisterm.A:Oh,good.LasttermmyroommateranoutandhadtopayforB:Yea.It’sanissue.Icouldn’thelpbutnotice,youareprintinganapplicationfortheGreenA:Yea.Aninternship,throughthebiologydepartment.B:Oh.Areyoumajoringinbiology?A:Engineeringactually.Theinternshipisnotreallyrelatedtomystudies,butitsoundedinteresting;andit’sgoodtobranchout-learnaboutnewthingsindifferentareas.B:Oh!Ok.IaskbecauseIhaveafriend,someoneIgraduatedwith,whoworksintheGreenHouse.Hesaysit’sagreatplacetowork.A:Cool!Isyoufriendinvolvedintheirsummeryouthprogramatall?Thatiswhattheinternshipisfor-helrunthatprogram.Ithinkalotofpeoplewillapplyforthisinternship.It’dbegreattoknowsomebodyontheinside!B:Idon’tknowexactlywhathedoesthere.Ididn’tevenknowtherewasayouthA:Oh.Iheardaboutitontheradio,theparticipantsaregonnabeplantinggrassesandflowersandstuffforthenewgreenroocampus.B:GreenA:Yea.TheyarebasicallygardensonthetopsofB:Why?SostudentsherecanstudyplantgrowthorA:Thatisnotwhattheysaidontheradio.Theysaidthatgreenroofscanlowerthetemperatureinsidethebuilding,soyoudon’thavetospendasmuchonair-conditioning.B:ThatisagoodA:Yea!Andalsointhecity,stormwaterrunoffs,youknow,rainwaterthatrunsintosewersandlocallakesandrivers.Thisrunoffapparentlypicksupalotofpollutionfromthepavement;greenroofsabsorbsomeofthatrain,whichreducesrunoff,whichinturnhelpsthewaterquality.Sobasically,umnanomaterialisanextraordinarythinsheetofmaterial,oftenafilmoranengineeredsurfaceofsomekindthat'slessthanfive-atom'sthick.Thereisanumberofdifferentnanomaterialsoutthererightnow,butwhati'dliketofocusontodayisGraphene.NowIlikegraphenecausethereisanumberofexcitingapplicationswhereitmayproveveryuseful.Asthenamesuggests,graphene'sderivedfromgraphite,thestuffinthecoreofpencils.Graphite'smadeoflayersofcarbonatomsandifyoustripoffthethinnestpossiblelayerofgraphite,alayerthat'sjustoneatomthick,you'vegotgraphene.Grapheneisthestrongestmaterialevermade.Itsstrengthisduetoitsperfectcrystalinatomicstructurewhichlookslikechickenwireunderamicroscopeactually.Youcouldcomparegraphenetodiamondbecausetheyarebothmadeofcarbonatomsthatarerangedinasimpleandregularpattern.Butunlikediamond,graphene'sincrediblyflexible,akintoplasticwrap.Andbecauseofitsatomicstructure,grapheneisalsoanoutstandingheatconductor.Electronsspeedthroughthismaterialmuchfasterthantheycanthroughothermaterials.Um,it'sbeenafewdecadessincegraphenewasfirstidentifiedasapotentialnanomaterialin1947,tobeprecise.Somescientistscameupwiththeideathatamateriallikethiscouldbeusedinavarietyofways,butotherswereskepticalbecausereally,howdoyoumakeasheetofamaterialthat'sjustone-atomthick?Inthe1980sand90s,manyresearchgroupstriedtoproducegraphenewithlittlesuccess,butin2004,agroupinManchesterEnglandcreatedthefirstgraphenesamplebysimple,mechanical,exfoliation.Basically,theyplacedasmallpieceofgraphitebetweentwopiecesofadhesivetape,pulledthetapesapartandrepeatedthisprocessoverandoveruntiltheyhadextractedalayerthatwasjustone-atomthick.Andthisnewsexcitedthescientificcommunitybecausenowitmeantthatgraphenecouldbeinvestigatednotonlytheoretically,butalsoexperimentally.Whenexperimentsrevealedthehighmobilityofelectronsthroughgraphene,thismaterialbecameparticularlypromisinginthefieldofelectronics.Itmightbeusedtomaketransistors,andcomputermicrochips.Asyouknow,thedevelopmentofmicrochipsandtransistorshasbeenbasedonsiliconformorethan40years.Nowsiliconisthematerialthatallowedustocreateeverfasterandsmallermicrochipswhichtransformedcomputersfromhugemachinestosmallportabledevices.Butasmobilephones,musicplayersandotherdeviceskeepgettingsmallerandfaster,we'renowpushingthecapacityofsilicon.Sowehopethatgraphenecaneventuallyreplacesiliconasasemi-conductor.Asyouknow,asemi-conductorisamaterialthatdeliverselectricalchargesbetweenelectrons.Recallthebasicunitsofdigitalinformationareonesandzeros.Onemeansthereisasignalandzeromeans