简介:物质的颗粒度大小及分布,直接联系着物质的性能和应用。过去,对常规10-20gm的炸药颗粒度研究较多,而对超细炸药颗粒度研究较少。与常规炸药相比,超细炸药存在许多特殊性,如颗粒间更易团聚不易分散、在溶剂里表现出不同于大颗粒的溶解性等,使测试变得更复杂。以超细TATB、超细BTF、超细HNS、超细RDX和超细HMX为对象,使用LS-230型激光粒度仪,对颗粒度测试过程中涉及的各种测试条件(如分散介质的选择、分散剂选择、超声时间的确定、光学模型设置、运行时间等)进行研究,获得各种超细炸药的最佳测试条件,形成基本完善的测试方法,并将测试结果与扫描电子显微镜及英国马尔文公司的Matersizer2000型激光粒度仪的测试结果进行比较。
简介:Thedevelopmentofthehydrogenelectrodeisvitalfortheapplicationofalkalinepolymerelectrolytefuelcells(APEFCs).Inthisstudy,aseriesofNi(OH)2decoratedNi/Ccatalysts(Ni(OH)2-Ni/C)werepreparedbyathree-stepelectrochemicaltreatmentofNi/C.TheexistenceofNi(OH)2wasdemonstratedbyX-rayphotoelectronspectroscopy(XPS),andthesurfacemolarratioofNi(OH)2/Niofthesampleswasestimatedviaanelectrochemicalmethod.TheHORcatalyticactivityofthecatalystswasevaluatedbyarotationdiskelectrode(RDE)method,anda'volcanoplot'wasestablishedbetweentheHORexchangecurrent(j0)andthesurfacemolarratioofNi(OH)2/Ni.Ontopofthe'volcano',thesurfacemolarratioofNi(OH)2/Niis1.1:1,thej0ofwhichwas6.8timesofthatofNi/C.ThestabilityofthesamplestowardHORwasevaluatedtobegood.OurstudyaddedasystematicexperimentalevidencetotheHORresearch,showingthattheHORcatalyticactivityofNicanbedeliberatelycontrolledviadecorationofNi(OH)2,whichmayhelpunderstandingtheHORmechanismonNi.
简介:Threetypesofcarbonnano-onions(CNOs)includingNi@CNOs.Fe3C@CNOsandFe0.64Ni0.36@CNOsnanoparticleshavebeensynthesizedbycatalyticdecompositionofmethaneat850℃usingnickel,ironandiron-nickelalloycatalysts.Comparativeandsystematicstudieshavebeencarriedoutonthemorphology,structuralcharacteristicsandgraphiticcrystallinityoftheseCNOsproducts.Furthermore,theelectrochemicalhydrogenstoragepropertiesofthreetypesofCNOshavebeeninvestigated.MeasurementsshowthattheNi@CNOshavethehighestdischargecapacityof387.2mAh/g,coiTespondingtoahydrogenstorageof1.42%.ThiscomparisonstudyshowstheadvantagesofeachcatalystinthegrowthofCNOs.enablingthecontrollablesynthesisandtuningthepropertiesofCNOsbymediatingdifferentmetalsandtheiralloyforusinginthefuelcellsystem.
简介:HydrotalciteprecursorsofLamodifiedNi-Al2O3andNi-SiO2catalystspreparedbyco-precipitationmethodandthecatalyticactivitieswereexaminedfortheproductionofCOx-freeH2byCH4decomposition.Physico-chemicalcharacteristicsoffresh,reducedandusedcatalystswereevaluatedbyXRD,TPRandO2pulsechemisorptions,TEMandBET-SAtechniques.XRDstudiesshowedphasesduetohydrotalcite-likeprecursorsinovendriedformproduceddispersedNiOspeciesuponcalcinationinstaticairabove450C.Ramanspectraofdeactivatedsamplesrevealedthepresenceofbothorderedanddisorderedformsofcarbon.Ni-La-Al2O3catalystwithamoleratioofNi:La:Al=2:0.1:0.9exhibitedtremendouslyhighlongevitywithahydrogenproductionrateof1300molH2mol1Ni.AdirectrelationshipbetweenNimetalsurfaceareaandhydrogenyieldswasestablished.
简介:设计了一种结构简单、噪声低、功耗小的溴化镧(LaBr3:Ce)γ谱仪前端读出电子学电路。该电路包括电压灵敏前置放大电路、谱仪放大电路和供电电源3部分,电路的设计基于传统核电子学方法和较新的电子元器件,采用低噪声设计技术,在能谱测量中获得了较高的能量分辨率。文中首先介绍了电路的设计方案,包括各部分电路原理、功能和设计要点;然后开展了电路仿真和电路板设计;最后通过实验进行电路功能验证。实验表明:基于研制的前端读出电子学电路、溴化镧(LaBr3:Ce)探测器及数字多道分析器组成的γ谱仪系统,对137Cs662keVγ能峰的能量分辨率可达2.7%,谱仪系统性能稳定。
简介:AMonteCarlosimulation,withtheenergeticsdescribedbytheembeddedatommethod,hasbeenemployedtostudythephysicalbehaviourofboronatomsduringrelaxationoftheNi3AlBxgrainboundary,IthasalsobeenusedtocalculatenotonlythepeakconcentrationsofNiandBandthevalleyconcentrationofAlatthegrainboundary,butalsothedependenceofthegrainboundarycohesionontheBbulkconcentration.DuringrelaxationofimpureNi3Algrainboundaries,wesuggestthat,asthesegregatingspecies,theBatomseitherinsertintointersticesinthegrainboundaryorsubstituteNiatoms.Meanwhile,astheinducingspecies,theyinduceNiatomstosubstituteforAlatoms.Calculationsshowthatintheequilibrium,whentheBbulkconcentrationxincreasesfrom0.1to0.9thepeakconcentrationofBincreases,thepeakconcentrationofNimaximizeswhilethevalleyconcentrationofAlminimizesatx=0.5,Thecalculationsalsoshowthebestcohesionofthegrainboundaryatx=0.5。
简介:Asamemberof1Dnanostructuredmaterials,theferromagneticandnonmagneticmultilayernanowiresexhibittremendouspotentialapplicationsinmanyfieldsduetotheiruniquemagneticandelectricalproperties.Thebasicpropertyofmultilayernanowirearrays,suchascoercivity,iscrucialimportantforthefutureapplication.Inordertoobtainthecoercivityinformation,besidesdirectlymeasuringitthroughexperiment,theoreticalcalculationalsoprovidesausefulandfastwaytoevaluatethemultilayer’scoervicity.Fig.1(a)and(b)demonstrateasinglemultilayernanowireandnanowirearraysembodiedinamatrix,respectively.Inthiswork,byimprovingPant’smodel,wedevelopedthenewmodelandsuccessfullypredictedtherelationshipbetweenthecoercivitychangingofCu/Nimultilayernanowirearraysandstructualparameters.Fig.
简介:AdsorptionofhydrogenmoleculesonanNi-doped(8,0)single-walledcarbonnanotube(SWNT)isinvestigatedbyusingfirst-principlesdensityfunctionalcalculations.TheresultshowsthatasingleNiatomadsorbedonthebridgesiteofthetubecouldcannotdissociatetheH2,howeveritcanchemisorbthreeH2atmost,withtheaveragebindingenergyperH2suitableforthehydrogenstorageattheroomtemperature.MoreH2wouldphysisorbaroundanNiatomweakly.AsfortheSWNTwithanNidimeradsorbed,wefindthatwhentheH2approachestheNi-Nibond,itdissociateswithoutovercominganybarrierandmakesbondswithNiatom.
简介:Immobilizingbiocomponentsonsolidsurfacesisacriticalstepinthedevelopmentofnewdevicesforfuturebiological,medical,andelectronicapplications.Therefore,numerousintegratedfilmswererecentlydevelopedbyimmobilizingdifferentproteinsorenzymesonelectrodesurfaces.Inthiswork,hemeproteinsweresafelyimmobilizedontomacroporousnickel-basedelectrodeswhilemaintainingtheirfunctionality.Suchmodifiedelectrodesshowedinterestingpseudo-capacitivebehavior.Amonghemeproteins,hemoglobin(Hb)filmhasahigherelectrochemicalperformanceandgreatercharge/dischargecyclingstabilitythanmyoglobin(Mb)andcytochromeC(CytC).Thehemegroupinanalkalinemediumcouldinducetheformationofsuperoxidesontheelectrodesurface.Thesecapacitivefeaturesofhemeprotein-NielectrodewererelatedtostrongbindingsitesbetweenhemeproteinsandporousNielectrode,theaccumulationofsuperoxideorradicalsontheNisurface,andfacileelectrontransferandelectrolytediffusionthroughthethree-dimensionalmacroporousnetwork.Thus,thesenewprotein-basedsupercapacitorshavepotentialuseinfree-standingplatformtechnologyforthedevelopmentofimplantableenergy-storagedevices.
简介:基于随机介质的谱分解理论,建立了二维多孔介质的细观模型,发展了多孔介质传热问题的多松弛格子Boltzmann方法求解算法,模拟了恒定热流加载下含基体孔隙复合材料的传热过程,计算了碳化硅多孔材料的等效热导率。结果表明,多孔介质的传热过程与孔隙率、孔隙结构密切相关,孔隙率越大材料传热性能越差,等孔隙率条件下,多孔介质沿某一方向的等效热导率随该方向孔隙自相关长度的增加而变大。
简介:Au/Ce1xZrxO2catalysts(x=0-0.8)werepreparedbyadeposition-precipitationmethodusingCe1xZrxO2nanoparticlesassupportswithvariableCeandZrcontents.TheirstructureswerecharacterizedbycomplimentarymeanssuchasX-raydiffraction,Raman,scanningtransmissionelectronmicroscopyandX-rayphotoelectronspectroscopy(XPS).TheseAucatalystspossessedsimilarsizesandcrystallinephasesofCe1xZrxO2supportsaswellassimilarsizesandoxidationstatesofAunanoparticles.TheoxidationstateofAunanoparticleswasdominatedbyAu0especiallyinCOoxidation.TheiractivitieswereexaminedinCOoxidationatdifferenttemperaturesintherangeof303333K.TheCOoxidationratesnormalizedperAuatomsincreasedwiththeincreasingCecontents,andreachedthemaximumvalueoverAu/CeO2.Suchchangewasinparallelwiththechangeintheoxygenstoragecapacityvalues,i.e.theamountsofactiveoxygenspeciesonAu/Ce1xZrxO2catalysts.TheexcellentcorrelationbetweenthetwopropertiesofthecatalystssuggeststhattheintrinsicsupporteffectsontheCOoxidationratesisrelatedtotheeffectsontheadsorptionandactivationofO2onAu/Ce1xZrxO2catalysts.SuchunderstandingonthesupporteffectsmaybeusefulfordesigningmoreactiveAucatalysts,forexample,bytuningtheredoxpropertiesofoxidesupports.
简介:UsingtheefectiveHamiltonianmethod,weanalyzetheB0-ˉB0mixingintheextensionofthestandardmodel(SM)wherebaryonnumberandleptonnumberarelocalgaugesymmetries.ThenumericalresultsindicatethecorrectionfromtheextraparticlestothemassdiferencemBissignificant.Thereisa60%enhancementcomparedtotheSMpredictionformBatmost,whichagreeswiththecurrentexperimentalresult.