学科分类
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21 个结果
  • 简介:Ashortoverviewofthetheoryofaccelerationofthinfoilsdrivenbytheradiationpressureofsuperintenselasersispresented.Asimplecriterionforradiationpressuredominanceatintensitiesaround5×1020Wcm-2isgiven,andthepossibilityforfastenergygainintherelativisticregimeisdiscussed.

  • 标签: LIGHT SAIL radiation pressure laser–plasma ACCELERATION
  • 简介:寄生虫能影响他们的主人种类的许多方法是用途径的一个范围的强烈学习的焦点。在这上下文的一个特别地有希望却在使用得下面的方法是试验性的进化,因为它允许暴露于对比条件的已知的人口的指向的操作。把这个方法用于昆虫宿主和他们的联系寄生虫的学习的强壮的潜力被昆虫暴露于寄生虫的很少可得到的长期的实验表明。在这评论,我们总结这些研究,它响应寄生虫压力,内在的机制,以及相关基因回答交付了珍贵卓见进抵抗的进化。我们进一步在免疫,生活历史,和复制的互连的上下文从相关人工的选择研究估计调查结果。另外,我们更详细地讨论很多个学习得好的Triboliumcastaneum-Nosemawhiteicoevolution实验并且为研究提供建议。明确地,我们建议未来实验应该也用nonmodel主人被执行并且应该合并形成对照的试验性的条件,例如人口尺寸或环境。最后,我们期望那补充说例如,第三一秒合伙寄生虫或共生者,到一个主人寄生虫,系统能强烈影响(co)进化动力学。

  • 标签: 实验条件 共同进化 寄生虫 宿主 昆虫 进化动力学
  • 简介:不平常的大气的轻排出物从位于华东的山东省的一个车站被观察。这些事件的主要形态学包括一个明亮的发光点,它与井在文学认出了的短暂发光事件(TLE)的任何类型清楚地不同,例如鬼怪,光圈,矮子,巨大的喷气,蓝喷气,和蓝跑步者。在从闪电察觉网络的四个如此的轻排放事件和数据的观察之间的比较不在邻近的区域揭示在这些事件和强烈闪电活动之间的关联。事件在这报导纸可以与尚待与进一步的观察和互补闪电测量被调查的机制暗示新现象的存在。

  • 标签: 光发射 地面观测 大气 雷电活动 中国东部 雷电测量
  • 简介:Thephotoacoustictomographybyusingthehandheldprobehasagreatpotentialinclinicalbreastimaging.However,theshapeoftheprobelimitsthechoiceoflightdeliveryinthissetup.Inthisletter,westudytwocommonlyusedilluminationtypesforhandheldprobe:bright-fieldilluminationanddark-fieldillumination.Ourresultsdemonstrateseveralparametershaveimportantimpactonthephotonfluenceindeepbreasttissue.Theresultswillhelptooptimizethedesignofthephotoacousticbreastimagingsystemwithahandheldprobe.

  • 标签: 手持式 探头 成像仿真 光声 光传输 乳腺
  • 简介:Anintegratedmethodbasedonopticalanddigitalimageprocessingispresentedtosuppressspeckleindigitalholography.Aspatiallightmodulatorisadoptedtointroducerandomphasestotheilluminatingbeam.Multiplehologramsarereconstructedandsuperimposed,andtheintensityisaveragedtosmooththenoise.Theadaptivealgorithmbasedonthenonlocalmeansisdesignedtofurthersuppressthespeckle.Thepresentedmethodiscomparedwithothermethods.Theexperimentalresultsshowthatspecklereductionisimproved,andtheproposedmethodiseffectiveandfeasible.

  • 标签: 斑点噪声抑制 空间光调制器 数字全息 非局部 均值算法 数字图像处理
  • 简介:Earthquakeengineeringresearchanddevelopmenthavereceivedmuchattentionsincethefirsthalfofthetwentiethcentury.Thisvaluableresearchpresentedahugestepforwardinunderstandingearthquakehazardmitigation,whichresultedinappreciablereductionoftheeffectsofpastearthquakes.Nevertheless,the2011Tohokuearthquakeandthesubsequenttsunamiresultedinmajordamage.Thispaperpresentsthetimelineofearthquakemitigationandrecovery,asseenbytheauthors.Possibleresearchdirectionswheretheauthorsthinkthatmanyopenquestionsstillremainareidentified.Theseareprimarilybasedontheimportantlessonslearnedfromthe2011Tohokuearthquake.

  • 标签: RESEARCH needs EARTHQUAKE ENGINEERING quick RECOVERY
  • 简介:Two-dimensional(2-D)BiVO4nanosheets-graphene(GR)compositeswithdifferentweightadditionratiosofGRhavebeenpreparedviaafacilewetchemistryprocess.X-raydiffraction(XRD),Ramanspectra,X-rayphotoelectronspectra(XPS),UV-visdiffusereflectancespectra(DRS),field-emissionscanningelectronmicroscopy(FE-SEM),transmissionelectronmicroscopy(TEM),nitrogenadsorption-desorption,transientphotocurrentresponseandphotoluminescence(PL)spectrawereemployedtodeterminethepropertiesofthesamples.ItisfoundthatBiVO4nanosheetscouldpavewellonthesurfaceofgraphenesheets.BiVO4nanosheets-GRcompositeswithaproperadditionamountofGRexhibitedhigherphotocatalyticactivitythanbareBiVO4nanosheetstowardliquid-phasedegradationofrhodamineB(RhB)andmethylorange(MO)undervisiblelightirradiation.TheenhancementofphotocatalyticactivitiesofBiVO4nanosheets-GRcompositescanbeattributedtotheeffectiveseparationofphotoexcitedelectron-holepairs.Thisworknotonlyprovidesasimplestrategyforfabricatingspecific2-Dsemiconductor-2-DGRcomposites,butalsoopensanewwindowofsuch2-Dsemiconductor-2-DGRcompositesasvisiblelightphotocatalyststowardanimprovedvisiblelightphotoactivityinpurifyingpollutedwaterresources.

  • 标签: 可见光照射 光催化活性 复合材料 纳米 石墨 X-射线光电子能谱
  • 简介:Graphene(GR)-CdSnanocompositeswithdifferentweightadditionratiosofGRhavebeenassembledbyafacilesolvothermaltreatment.TheGR-CdSnanocompositephotocatalystwithanappropriateratioofGRexhibitsenhancedphotoactivityforselectivereductionofaromaticnitrocompoundstothecorrespondingaromaticaminesinwaterundervisiblelightirradiationascomparedwithblank-CdS.ThecharacterizationofGR-CdSnanocompositephotocatalystsbyacollectionoftechniquesdisclosesthat:i)GRcantunethemicroscopicmorphologyofCdSnanoparticlesandimprovelightabsorptionintensityinthevisiblelightregion;ii)GRscaffoldsactasanelectronreservoirtotrapandshuttletheelectronsphotogeneratedfromCdSsemiconductorunderthevisiblelightillumination;iii)theintroductionofGRenhancestheadsorptioncapacityofGR-CdSnanocompositestowardthesubstrates,aromaticnitrocompounds.ThesynergisticeffectofthesefactorsshouldaccountforthephotoactivityadvancementofGR-CdSnanocompositestowardtheprobereactions.Furthermore,becausethephotogeneratedholesinthesystemaretrappedbythequenchingagentammoniumoxalate,theas-obtainedGR-CdSphotocatalystisstableduringthephotocatalyticreductionreactions.Areasonablemodelhasalsobeenproposedtoillustratethereactionmechanism.

  • 标签: 纳米复合光催化剂 纳米复合材料 硫化镉 可重复使用 还原过程 石墨
  • 简介:Measurementoflightdistributioninbiologicaltissuecontributestoselectingstrategyandoptimizingdoseforbiomedicalapplication.Inthisletter,aphotoacousticmethodcombinedwithMonteCarlosimulationwasusedtoestimatethethree-dimensionallightdistributioninbiologicaltissue.Thelightdistributionwasproducedbyacylindricaldiffuserwhichinterposedintotissues.Thelightprofilesobtainedbythemethodwerecomparedtothosedetectedbyphotodiodes.Theexperimentalresultsdemonstratethefeasibilityofthismethod.Theapproachcanplayasignificantroleforphoto-dosimetryinbiomedicalphototherapy.

  • 标签: 生物组织 光分布 扩散器 光声成像 三维 圆柱形
  • 简介:Thesteadyanddynamicpropertiesarecomparativelyinvestigatedforthen-dopedandnon-dopedInGaNLEDs.Thesimulatedresultsshowthatthen-dopedLEDexhibitsthesuperiorluminescenceandmodulationperformance,whichismainlyattributedtothehighercarrierradiativerateofn-dopedLED.Theresultscanexplainthereportedexperimentalresultsperfectly.

  • 标签: 发光二极管 N型掺杂 动态性能 氮化铟镓 稳态 势垒
  • 简介:Weinvestigatetheeffectsofspontaneouslygeneratedcoherence(SGC)onboththesteadyandtransientgainpropertiesinafour-levelinverted-Y-typeatomicsysteminthepresenceofaweakprobe,twostrongcoherentfields,andanincoherentpump.Forthesteadyprocess,wefindthattheinversionlessgainmainlyoriginsfromSGC.Inparticular,wecanmodulatetheinversionlessgainbychangingtherelativephasebetweenthetwofields.Moreover,theamplitudeofthegainpeakcanbeenhancedandtheadditionalgainpeakcanappearbychangingthedetuningofthecouplingfield.Asforthetransientprocess,thetransientgainpropertiescanalsobedramaticallyaffectedbytheSGC.ComparedtothecasewithoutSGC,thetransientgaincanbegreatlyenhancedwithcompletelyeliminatedtransientabsorptionbychoosingtheproperrelativephasebetweenthetwofields.Andtheinverted-Y-typesystemwithSGCcanbesimulatedinbothatomicandsemiconductorquantumwellsystemsavoidingtheconditionsofSGC.

  • 标签: 相干态光场 原子系统 瞬态过程 相位控制 稳态 光放大
  • 简介:Wefabricatewhitephosphorescentorganiclight-emittingdiodes(PHOLEDs)withthreedopantsanddoubleemissivelayer(EML)toachievecolorstability.ThewhitePHOLEDsuseFIrpicdopantforblueEML(BEML),andIr(ppy)3:Ir(piq)3dopantsforgreen:redEML(GR-EML)withN,N′-dicarbazolyl-3,5-benzene(mCP)ashostmaterial.ThicknessesofB-EMLandGR-EMLareadjustedtoformanarrowrecombinationzoneattwoEML’sinterfaceandchargetrappinghappensinEMLaccordingtowidehighestoccupiedmolecularorbitaland/orlowestunoccupiedmolecularorbitalenergybandgapofmCPandsmallerenergybandgapofdopants.ThetotalthicknessofbothEMLsisfixedat30nminthedevicestructureofITO(150nm)/MoO3(2nm)/N,N′-diphenyl-N,N′-bis(l-naphthyl-phenyl)-(l,l′-biphenyl)-4,4′-diamine(70nm)/mCP:Firpic-8.0%(12nm)/mCP:Ir(ppy)3-3.0%:Ir(piq)3-1.5%(18nm)/2′,2′,2′′-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)(30nm)/8-hydroxyquinolinolato-lithium(2nm)/Al(120nm).WhitePHOLEDshows18.25cd/Aofluminousefficiencyandwhitecolorcoordinatesof(0.358and0.378)at5000cd/m2andcolorstabilitywithslightCIEXYchangeof(0.028and0.002)asincreasingluminancefrom1000to5000cd/m2.

  • 标签: 有机发光二极管 颜色稳定性 掺杂剂 发光层 磷光 分子轨道能级
  • 简介:AnovelSr2CuInO3Soxysulfidep-typesemiconductorphotocatalysthasbeenpreparedbysolidstatereactionmethodanditexhibitsintriguingvisiblelightabsorptionpropertieswithabandgapof2.3eV.Thep-typesemiconductorcharacterofthesynthesizedSr2CuInO3SwasconfirmedbyHallefficientmeasurementandMott-Schottkyplotanalysis.First-principlesdensityfunctionaltheorycalculations(DFT)andelectrochemicalmeasurementswereperformedtoelucidatetheelectronicstructureandtheenergybandlocations.Itwasfoundthattheas-synthesizedSr2CuInO3Sphotocatalysthasappreciateconductionandvalencebandpositionsforhydrogenandoxygenevolution,respectively.Photocatalytichydrogenproductionexperimentsunderavisiblelightirradiation(λ>420nm)werecarriedoutbyloadingdifferentmetalandmetal-likecocatalystsonSr2CuInO3SandRhwasfoundtobethebestoneamongthetestedones.

  • 标签: 半导体光催化剂 可见光照射 Mott-Schottky图 P型 制氢 密度泛函理论
  • 简介:TiO2-loadedactivatedcarbonfibers(ACF)werepreparedbyahydrothermalmethod.Thesampleswerecharacterizedbyscanningelectronmicroscopy(SEM),X-raydiffraction(XRD),Fouriertransforminfrared(FT1R)spectrometryandUV-visdiffusereflectancespectra(DRS).SEMimagesshowedthattheTiO2nanoparticlesweredepositedonthesurfaceofACF,andtheparticlesizeandloadingamountofTiO2werevariedbychangingtheinitialconcentrationoftetrabutyltitanate(TBOT).TheresultsofanashexperimentshowedthattheloadingamountsofTiO2were18.4%,43.3%,52.5%,75.1%,and91.1%forinitialconcentrationsofTBOTof0.07,014,0.21,0.28,and0.35mol/L,respectively.PhysicalinteractionsplayedanimportantroleintheformationofTiO2/ACFcompositefibersthatabsorbUVandvisiblelight.ComparedwiththoseofACF,improvedadsorptionandphotocatalyticactivitytowardRhodamineB(RhB)wereobservedforTiO2/ACFcompositefiber.TheRhodamineBcouldberemovedefficientlybyTiO2/ACFcompositefibers,andtheTiO2loadingamounthadasignificanteffectonthephotocatalyticactivityofTiO2/ACFcompositefibers.

  • 标签: 纳米TiO2 光催化活性 可见光照射 吸附性能 负载量 活性炭纤维