学科分类
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142 个结果
  • 简介:Thecoordinationpolymer,(Nd(H2O)5)2(2,6-AQDS)3·2H2Owhere2,6-AQDS=2,6-anthraquinonedisulfonate,hasbeensynthesisedviaahydrothermalroute.Structurally,itconsistsoflayersofmonomericNdpolyhedrawhicharelinkedby2,6-AQDSanionsformingapolymeric,three-dimensionalnetwork.EachNdatomisninecoordinate,bondingtofivewatermoleculesandtofouroxygenatomsfromfour2,6-AQDSanionswhichinturnpillarthelayersbybridgingtwoNdatomsinonelayer,andcoordinatingtoasingleNdintheother.

  • 标签: 配位聚合物 水热法合成 晶体结构 络阴离子 氧原子
  • 简介:NanocrystallineSnO2wassynthesizedbydirectmixingandgrindingofSnCI4-5H2OandNaOHatroomtemperature,followedbycalcinationatdifferenttemperaturesfordifferenttimesinair.ProductsampleswerecharacterizedbyX-raydiffractionandtransmissionelectronmicroscope,revealingthattheamorphousprecursorSnO2wastransformedtocrystalsat200℃for3h,andthattheaverageparticlesizeincreaseduponraisingthecalciningtemperatureorprolongingthecalciningtime.Themechanismofthephasetransformationoftheproductsisdiscussed.

  • 标签: 二氧化锡纳米晶体 纳米材料 固态反应 焙烧 X射线衍射分析 透射电子显微镜分析
  • 简介:连贯的多角形的粒子的二维的分离元素模型(DEM)模拟被开发了估计点来源颤动的利益在楔形的hoppers导致流动。使用的particleparticle相互作用模型基于一个多接触原则。没有颤动,学习的第一部分在严肃下面调查了粒子分泌物决定批评的孔尺寸(Bc)就作为粒子形状的功能支撑流动。多角形形状的粒子比圆形的粒子需要一个更大的孔,这被显示出。当粒子顶点的数字增加,Bc减少,这也被显示出当粒子顶点的数字增加。圆形的粒子的增加以一种线性方式支持多角形的流动。学习的第二部分证明那颤动能提高流动,有效地减少Bc。模型表明了震荡器地点(高度)的重要性,与在提高的以前的连续统模型结果,和颤动振幅一致流动。

  • 标签: 动力效应模型 固体 振动 仿真
  • 简介:Uniformlysizedα-Fe2O3hexagonalplateletsweresynthesizedbyahydrothermalprocessusingFe(OH)3suspensionandlargeamountofNaOH.ThereactionproductswerecharacterizedbyX-raydiffraction(XRD),scanningelectronmicroscopy(SEM),transmissionelectronmicroscopy(TEM),selectedareaelectrondiffraction(SAED),andavibratingsamplemagnetometer(VSM).Theresultsshowthatthehexagonalplateletsarefine,monodisperseandconsistingofsingle-crystals.Themagnetichysteresis(M-H)curveofthesamplesmeasuredatroomtemperatureindicatesthattheα-Fe2O3micro-plateletsexhibitferromagneticbehaviorswithrelativelylowcoercivity.

  • 标签: Fe2O3 六角片状 单分散 水热法合成 振动样品磁强计 扫描电子显微镜
  • 简介:Commerciallyavailablelatticescontainvariouskindsofmorphologicalimperfectionswhichresultingreatdegradationinlattices’mechanicalproperties,therefore,toobtainimperfectioninsensitivelatticestructureisobviouslyapracticalresearchsubject.Hierarchicalstructurematerialswerefoundtobeaclassofpromisinganti-defectmaterials.Thispaperbuildshierarchicallatticebyaddingsoftadhesiontolattice’scelledgesandnumericalresultsshowthatitsimperfectionsensitivitytomissingbarsisminorcomparedwiththeclassiclattice.Softadhesionwithappropriatepropertiesreinforcecelledge’sbendingstiffnessandthusreducethebendingdeformationinlatticecausedbymissingbarsdefect,whichisconfirmedbystatisticalanalysisofnormalizednodedisplacementsofimperfectlatticesunderhydrostaticcompressionandshearloads.

  • 标签: 敏感性 缺陷 晶格结构 二维 结构材料 力学性质
  • 简介:Inthisarticle,low-pressurecontrolmethodsforacombinedarcsubmergednanoparticlesynthesissystem(ASNSS)wasproposedanddevelopedforTiO2nanoparticlefabrication.Thephotocatalyticreactioniscarriedoutinaphotochemicalreactor.TheUVlightisobtainedfromUV-lampswithwavelengthof(253.7±0.8)nm.TheUV-Visspectrometryisusedtomonitortheabsorbancespectraofmethyleneblueasafunctionofilluminationtime.ExperimentalresultsshowthattherateconstantofphotocatalyticreactionofTiO2nanoparticlesformethyleneblueis0.0365min^-1.Thesurfaceadsorptionplaysanimportantroleinthedecompositionofmethyleneblue.ExperimentalresultsindicatethattheTiO2nanoparticlefluidpossessesexcellentphotocatalyticactivityinphotodegradationofmethyleneblue.

  • 标签: 二氧化钛 纳米颗粒流 光催化性质 ASNSS
  • 简介:Thereisaneedtostandardizemethodsassociatedwiththedispersionofnanomaterialsinnano(eco)toxicologicalinvestigations.Thefirststeptowardthisgoalistounderstandthedegreeofvariabilitythatexistsinnanomaterialdispersionspreparedbyusingdifferentprotocols.Usingtwocasestudies,thedegreeofvariabilityinTiO2nanomaterialdispersionswasassessedbydifferentialcentrifugalsedimentation(DCS)methods.Casestudy1addressesthevariabilitythatarisesfromvariationswithinoneprotocol,investigatingtheeffectsofdispersionaging,sonicationexposuretime,sonicationinthepresence/absenceofanicebath,materialsubsampling,particleconcentrationandhavingapre-wettingstep.Casestudy2addressesthevariabilitybetweenfourdifferentprotocolsdevelopedthroughpastresearchactivitiesandprojects.Theresultsindicatethatthereisalargedegreeofvariability(relativestandarddeviation(RSD)ofmeanparticlediameter=26%)inthedispersionofTiO2nanomaterialsbetweenthefourdifferentprotocolsstudiedandthatseveralstepsinadispersionprotocolarepotentialsourcesofvariation,withfinalparticleconcentrationbeingthemostsignificant.Theimplicationofthisstudyisclear:forthepurposeofdatacomparability,thereisaneedtoprovidetheexactdetailsofallstepsinvolvedinadispersionprotocol.

  • 标签: 分散体 协议 粒度分布 TIO2 纳米材料 相对标准偏差
  • 简介:Laminatedcompositematerialsarewidelyimplementedinseveralengineeringconstructions.Foritsrelativelightweight,thesematerialsaresuitableforaerospace,military,marine,andautomotivestructuralapplications.Toobtainsafeandeconomicalstructures,themodellinganalysisaccuracyishighlyrelevant.Sincemeshlessmethodsintherecentyearsachievedaremarkableprogressincomputationalmechanics,thepresentworkusesoneofthemostflexibleandstableinterpolationmeshlesstechniqueavailableintheliterature—theRadialPointInterpolationMethod(RPIM).Here,a2Dapproachisconsideredtonumericallyanalysecompositelaminatedbeams.Boththemeshlessformulationandtheequilibriumequationsrulingthestudiedphysicalphenomenonarepresentedwithdetail.Severalbenchmarkbeamexamplesarestudiedandtheresultsarecomparedwithexactsolutionsavailableintheliteratureandtheresultsobtainedfromacommercialfiniteelementsoftware.Theresultsshowtheefficiencyandaccuracyoftheproposednumerictechnique.

  • 标签: RADIAL POINT interpolators RPIM LAMINATED BEAM
  • 简介:在组成的部件之间的有瑕疵的结合能极大地影响合成结构的性质。处于2Dfibrereinforced的问题产生的有瑕疵的接口的不同类型的asymptotic分析合成材料被建议。执行学习基于管理biharmonic问题的asymptotic减小进二个泛音问题。所有答案在一种关上的分析形式被获得。获得的结果能被用于撤退和pushout测试的计算,以及为合成材料的破裂的调查。

  • 标签: 复合材料界面 纤维增强 2D 复合材料结构 双调和问题 组成成分
  • 简介:ThecaptureoforthophosphatesandtotalphosphorusfromthePudongCanalriverinthePudongDistrictofShanghaibyTiO2nanoparticlesisstudiedusingarotatingphotoreactorandthenano-TiO2photocatalystDegussaP25.TheeffectsofUVirradiationintensityinarangeof20-74mW/cm2.theloadingoftheTiO2nanoparticlesinarangeof0.05-0.1g/L,irradiationtimeupto4h,andpHvaluesinarangeof2-10.5onthecaptureefficiencyareinvestigated.TheresultsshowthatthecaptureoforthophosphatesandtotalParesignificantlyenhancedbyUVirradiation;ataloadingof0.1g/Landanirradiationintensityabove36mW/cm2,orthophosphatesandtotalphosphorusarerapidlycapturedbyTiO2nanoparticles,causinganobservedreductionfrom0.4mg/Ldownto0.02mg/L.pHvaluesinarangeof2-10.5havelittleeffectonthecaptureefficiencyoforthophosphatesandtotalphosphorus.

  • 标签: 纳米二氧化钛光催化剂 紫外光照射 捕获 总磷 二氧化钛纳米粒子 地表水
  • 简介:Hierarchicalsea-urchin-shapedmanganeseoxidemicrospheresweresynthesizedviaatacilemetnoabasedonthereactionbetweenKMnO4andMnSO4inHNO3solutionat50C.Theaveragediameterofthemicrospheresis850nm.Themicrospheresconsistofacoreofdiameterof800nmandnanorodsofwidth50nm.Thenanorodsexistattheedgeofthecore.TheBrunauer-Emmett-Tellersurfaceareaofthesea-urchin-shapedmicrospheresis259.4m2/g.Apossibleformationmechanismofthehierarchicalsea-urchin-shapedmicrospheresisproposed.Thetemperaturefor90%conversionofbenzene(T90%)onthehierarchicalurchin-shapedMnO2microspheresisabout218℃.

  • 标签: 催化氧化 MNO2 型综合 平均直径 二氧化锰
  • 简介:ZrO2nanopowdersbasedstearicacidphasechangematerials(PCMs)werepreparedbyhigh-energymilling.Theconceptofheatcapacityfactor(HCF)wasusedtoanalyzethethermalpropertiesofthematerials.TheheatstoragepropertyofPCMs,containingthesamecontentofstearicacid(23%bymass)inthestartingmaterialsbutsynthesizedbydifferenttechnicalprocesses,wasinvestigatedbyusingHCF.Itwasfoundthattherewerevastinfluencesofdifferentdispersantsontheheatcapacity.Thesamplespreparedwithchloroformprovidedthebestheatstorageabilityinallsamplestested.

  • 标签: 相变材料 纳米粉体 硬脂酸 氧化锆 基础研究 蓄热性能
  • 简介:Anewmicromechanicsconstitutivemodelforpuredilatanttransformationplasticityofstructureceramicsisproposedinthispaper.Basedonthethermodynamics,micromechanicsandmicroscalet→mtrans-formationmechanismanalysisoftheTZPandPSZZrO2-containingceramics,ananalyticexpressionsoftheHelmholtzandcomplementaryfreeenergyoftheconstitutiveelementforthecaseofpuredilatanttransforma-tionisderivedforthefirsttimeinaself-consistentmanner.Bytheanalysisofenergydissipationinthefor-wardandreversetransformations,themieromechanicsconstitutivelawisderivedintheframeworkofHill-Rice’sinternalvariableconstitutivetheory.

  • 标签: CONSTITUTIVE element microscopic and MACROSCOPIC quantities
  • 简介:Afacilemethodforthesynthesisofsilver-silica(Ag-SiO2)Janusparticleswithfunctionalitiessuitablefortextileapplicationsisreported.SilicananoparticlespreparedbytheStobermethodwerefunctionalizedwithepoxy,amine,andthiolgroups,whichwereconfirmedbyFouriertransforminfraredanalysis.ThefunctionalizedsilicananoparticleswereusedtoproducePickeringemulsions,andtheexposedsurfacewasusedfortheattachmentofsilvernanoparticles(AgNPs)viathelow-temperaturechemicalreductionmethod.ThemorphologyandstructureoftheAg-SiO2Janusparticleswerecharacterizedbyscanningelectronmicroscopy,scanningtransmissionelectronmicroscopy,high-resolutiontransmissionelectronmicroscopy,energy-dispersiveX-rayanalysis,andUV-visspectroscopy.Becauseoftheirspecificfunctionalities,theseAg-SiO2Janusparticlesareproposedforapplicationsontextilesubstrates,astheycanovercomeseveraldrawbacksofdirectapplicationofAgNPsontextiles,suchasleaching,agglomeration,andinstabilityduringstorage.

  • 标签: 硅纳米颗粒 纺织应用 原位合成 环氧树脂 纺织品 二氧化硅纳米粒子
  • 简介:Thispaperpresentsanovelmechanicalattachment,i.e.,nonlinearenergysink(NES),forsuppressingthelimitcycleoscillation(LCO)ofanairfoil.Thedynamicresponsesofatwo-degree-of-freedom(2-DOF)airfoilcoupledwithanNESarestudiedwiththeharmonicbalancemethod.DiferentstructureparametersoftheNES,i.e.,massratiobetweentheNESandairfoil,NESofset,NESdamping,andnonlinearstifnessintheNES,arechosenforstudyingtheefectoftheLCOsuppressiononanaeroelasticsystemwithasupercriticalHopfbifurcationorsubcriticalHopfbifurcation,respectively.TheresultsshowthatthestructuralparametersoftheNEShavediferentinfluenceonthesupercriticalHopfbifurcationsystemandthesubcriticalHopfbifurcationsystem.

  • 标签: 非线性能 2自由度 振荡抑制 极限周期 机翼 量水槽
  • 简介:为它的高氧化抵抗,钇硅酸盐是为在在1600°C上面的温度的carbon-fiber-reinforcedcomposites的保护的涂层的一个重要候选人。一个新奇方法,由一起沉淀组成,弄干水花,热处理和plasma-densification,被开发准备Y2SiO5粉末为热喷洒。作文,形态学和综合Y2SiO5粉末的流动能力被XRD,SEM和霍尔流量计分别地调查。结果证明综合Y2SiO5粉末与高纯净是将近球形的。分别地,Y2SiO5粉末的明显的密度和流动能力是1.87g/cm3和37s/50g它为大气的血浆喷洒导致多达80%的高免职效率。

  • 标签: Y2SIO5 粉末流动 热喷涂 球形 大气等离子喷涂 制备
  • 简介:Aunifiedperturbationtheoryisdevelopedhereforcalculatingsolitarywavesofallheightsbyseriesexpansionofbaseflowvariablesinpowersofasmallbaseparametertoeighteenthorderfortheone-parameterfamilyofsolutionsinexactform,withallthecoefficientsdeterminedinrationalnumbers.Comparativestudiesarepursuedtoinvestigatetheeffectsduetochangesofbaseparameterson(i)theaccuracyofthetheoreticallypredictedwavepropertiesand(ii)therateofconvergenceofperturbationexpansion.Twoimportantresultsarefoundbycomparisonsbetweenthetheoreticalpredictionsbasedonasetofparametersseparatelyadoptedforexpansioninturn.First,theaccuracyandtheconvergenceoftheperturbationexpansions,appraisedversustheexactsolutionprovidedbyanearlierpaper[1]asthestandardreference,arefoundtodepend,quitesensitively,onchangesinbaseparameter.Theresultingvariationsinthesolutionarephysicallydisplayedinvariouswavepropertieswithdifferencesfounddependentonwhichproperty(e.g.thewaveamplitude,speed,itsprofile,excessmass,momentum,andenergy),onwhatrangeinvalueofthebase,andontherankoftheordernintheexpansionbeingaddressed.Secondly,regardingconvergence,thepresentperturbationseriesisfounddefinitelyasymptoticinnature,withtherelativeerrorδ(n)(therelativemean-squaredifferencebetweensuccessiveordersnofwaveelevations)reachingaminimum,δm,ataspecificorder,n=nm,bothdependingonthebaseadopted,e.g.n=11-12basedonparameterα(waveamplitude),nm,β=15onβ(amplitude-speedsquareratio),andnm.∈=17on∈(wavenumbersquared).Theasymptoticrangeisbroughttocompletionbythehighestorderofn=18reachedinthiswork.

  • 标签: 孤波 统一混乱理论 高次波 基础函数 渐近表示 力学
  • 简介:Nano-sizedhexagonalmagnesiumhydroxide(Mg(OH)2)withgooddispersibilitywassynthesizedbyadoubleinjection-hydrothermalmethod,utilizingpolyvinylpyrrolidone(PVP)asanadditiveandwithoptimizedprocessingparameters.SEMandBETanalysisshowedthatthemeanparticlesizeandspecificsurfaceareaoftheMg(OH)2particleswere174nmand50.77m2/g,respectively.TheFT-IRspectraandtheXRDpatternsshowedthatPVPwasadsorbedonthesurfaceoftheMg(OH)2crystal,thuseffectivelylimitingparticleagglomerationandhinderingcrystalgrowthalongthe(101)plane.TGAshowedadecreaseinthedecompositiontemperatureandanincreaseintheweightlossoftheMg(OH)2particlesduetoadditionofPVP.

  • 标签: 纳米尺寸 氢氧化镁 六边形 可控制备 MG(OH)2 聚乙烯吡咯烷酮