简介:Regardforthefuzzinessandtherandomnessinsomeacousticfields,amethodforthenumericalanalysisofthe2DacousticfieldwithFuzzy-Randomparameterswasproposedbasedontheequivalentconversionofinformationentropy.Intheproposedmethod,afuzzyrandomacousticfieldwastreatedasapurefuzzyacousticfieldorapurerandomacousticfieldbytransformingallthevariablesintofuzzyvariablesorrandomvariables.Perturbationfiniteelementmethodsforanalyzingthetwo-dimensionalacousticfuzzyandrandomfieldarededuced.Thesoundpressureresponseofa2Dacoustictubeandthe2Dacousticcavityofacarwithfuzzy-randomparameterswereanalyzedbytheproposedmethodandtheMonteCarlomethod,theresultsshowthattheproposedmethodcanbewellappliedtothenumericalanalysisofthe2Dacousticfieldwithfuzzy-randomparameters,andhasgoodprospectofengineeringapplication.
简介:WediscussthenonlinearSchrdingerequationwithvariablecoefficientsin2Dgraded-indexwaveguideswithdifferentdistributedtransversediffractionsandobtainexactbrightanddarksolitonsolutions.Basedonthesesolutions,wemainlyinvestigatethedynamicalbehaviorsofsolitonsinthreedifferentdiffractiondecreasingwaveguideswiththehyperbolic,GaussianandLogarithmicprofiles.Resultsindicatethatforthesameparameters,theamplitudeofbrightsolitonsintheLogarithmicprofileandtheamplitudeofdarksolitonsintheGaussianprofilearebiggestrespectively,andtheamplitudeinthehyperbolicprofileissmallest,whilethewidthofsolitonshastheoppositecase.
简介:AnovelmethodformodelingcellularmaterialsisproposedbasedonMATLABimageprocessingandsynchrotronX-raycomputedtomographyscanningtoobtainanaccuratecalculationresultofaluminumfoambasedonfiniteelementmodel.Themaximumentropyalgorithmisemployedtoobtainthebinarizationimage,andthemedianfilteringalgorithmisusedtoreducethenoiseafterbinarization.Theexternalcontourandinternalporesboundaryisextractedbythe"edge"functioninMATLAB,andthegeometricalmodelisreconstructed.Atwo-stepmeshalgorithmisadoptedtomeshthereconstructedgeometricalmodel.Accordingly,thefiniteelementmodelofaluminumfoamisestablishedbytheproposedmethodbasedonreconstructiongeometricalmodel.Thecompressionbehaviorofaluminumfoamisobtainedat25℃,100℃,200℃byABAQUS,andgoodagreementswithexperimentsareachievedbyapplyingthepresentreconstructionalgorithmandmodelingmethod.
简介:Amorphouscarbonandgrapheneco-modifiedLiFePO4nanocompositehasbeensynthesizedviaafacilepolyolprocessinconnectionwithafollowingthermaltreatment.Variouscharacterizationtechniques,includingXRD.Mossbauerspectra,Ramanspectra,SEM,TEM,BET,O2-TPO,galvanocharge-discharge,CVandEISwereappliedtoinvestigatethephasecomposition,carboncontent,morphologicalstructureandelectrochemicalperformanceofthesynthesizedsamples.TheeffectofintroducingwayofcarbonsourcesonthepropertiesandperformanceofLiFePO4/C/graphenecompositewaspaidspecialattention.Underoptimizedsyntheticconditions,highlycrystalizedolivine-typeLiFePO4wassuccessfullyobtainedwithelectronconductiveFe2PandFePasthemainimpurityphases.SEMandTEManalysesdemonstratedthegraphenesheetswererandomlydistributedinsidethesampletocreateanopenstructuredLiFePO4withrespecttographene,whiletheglucosederivedcarbonmainlycoatedoverLiFeP04particleswhicheffectivelyconnectedthegraphenesheetsandLiFePO4particlestoresultinamoreefficientchargetransferprocess.Asaresult,favorableelectrochemicalperformancewasachieved.Theperformanceoftheamorphouscarbon-grapheneco-modifiedLiFePO4wasfurtherprogressivelyimproveduponcyclinginthefirst200cyclestoreachareversiblespecificcapacityashighas97mAh·g-1at10Crate.
简介:Inthispaper,weareconcernedwiththeglobalexistenceandconvergenceratesofthesmoothsolutionsforthecompressiblemagnetohydrodynamicequationswithoutheatconductivity,whichisahyperbolic-parabolicsystem.TheglobalsolutionsareobtainedbycombiningthelocalexistenceandaprioriestimatesifH3-normoftheinitialperturbationaroundaconstantstatesissmallenoughanditsL1-normisbounded.Aprioridecay-intimeestimatesonthepressure,velocityandmagneticfieldareusedtogettheuniformboundofentropy.Moreover,theoptimalconvergenceratesarealsoobtained.
简介:用分子对接和三维全息原子场作用矢量方法对36个来曲唑类衍生物和34个阿那曲唑类衍生物与芳香化酶的作用模式进行了研究,建立了三维定量构效关系模型,并在分子水平上阐述了其结合机制.运用多元线性回归(MLR)建模,同时采用内部及外部双重验证的办法对所得模型稳定性能进行深入分析和检验.MLR建模的复相关系数(Rcum)、留一法交互校验复相关系数(QCV)和外部样本校验复相关系数(Qext)分别为0.863,0.782,0.796和0.931,0.825和0.641.预测模型具有良好的稳定性和预测能力.采用AutoDock4.2软件对药物与受体之间的结合方式进行了研究.运用这些信息能为进一步设计合成强效芳香化酶抑制剂,或筛选潜在的具有更强抑制活性的天然化合物提供帮助.
简介:AnefficientroutetoprepareL-glucoseandL-galactoseisdescribed.TheL-sugarsareachievedbyusingthestrategyofswitchingthefunctionalgroupsatC1andC5ofD-glucoseandD-mannose.TheoxidationandreductionofthesilylenoletheratC1andthelead(IV)tetraacetatemediatedoxidativedecarboxylationatC5arethekeysteps.L-GlucoseandL-galactosearepreparedinaconvenientandinexpensiveway.
简介:Inatwocomponentfermionsystem,themismatchedFermisurfacespreventtheformationofCooperpairsbetweenthetwospicesneartheiraverageFermisurface.Ourpreviouswork[1]hasshownthattheangledependenceofthenons-wavepairinggapcanreducetheeffectofthedifferenceμbetweentheFermisurfacesoftwospicesinasymmetricnuclearmatter.Ontheotherhand,intheheavyfermionsuperconductors,suchasCeCoIn5pressuredCeRhIn5NpPd5Al2andTl-basedcuprates,mayhaveacoupleofcommonfeatures,forexample,thed-wavepairingandastrongparamagneticeffect(thedifferenceofthetwoFermisurfacesμ).Therefore,theangledependenceofthepairinggapmayhavesignificantinfluenceinthesesystems.
简介:QuantumdynamicscalculationsforthetitlereactionH(2S)+S2(X3-Σg)→SH(X2Π)+S(3P)areperformedbyusingagloballyaccuratedoublemany-bodyexpansionpotentialenergysurface[J.Phys.Chem.A1155274(2011)].TheChebyshevrealwavepacketpropagationmethodisemployedtoobtainthedynamicalinformation,suchasreactionprobability,initialstate-specifiedintegralcrosssection,andthermalrateconstant.Itisfoundnotonlythatthereisareactionthresholdnear0.7eVinbothreactionprobabilitiesandintegralcrosssectioncurves,butalsothatboththeprobabilityandcrosssectionincreasefirstlyandthendecreaseasthecollisionenergyincreases.Theexistenceoftheresonancestructureinboththeprobabilityandcrosssectioncurvesisascribedtothedeeppotentialwell.Thecalculationoftherateconstantrevealsthatthereactionoccurringonthepotentialenergysurfaceoftheground-stateHS2isslowtotakeplace.
简介:采用密度泛函B3LYP/6-311G(d,p)方法对CH3F与C2H3的反应体系进行了理论研究,获得了反应的势能面信息及可能的微观机理.在QCISD(T)/6-311++G(d,p)水平上精确计算了各反应物种的单点能.结果表明,除抽提氢反应外,标题反应还存在抽提氟(R1)、消氟化氢(R2)、消氢(R3)和自由基形成(R4)四类反应.在QCISD(T)/6-311++G(d,p)//B3LYP/6-311G(d,p)水平上,R1,R2,R3和R4反应的能垒分别是163.9,152.2,209.8和224.2kJ·mol-1,相应反应能为-56.6,-164.3,-2.7和-156.0kJ·mol-1,所有反应均放热,为热力学允许的反应.
简介:采用HF/DFT的混合泛函PBE0和UPBE0优化了配合物[Os(PH3)2(CN)2(N^N)](其中N^N=2,2′-吡啶)的基态和激发态结构.在基态和激发态结构的基础上,利用含时密度泛函理论(TD-DFT)方法,结合极化连续介质(PCM)模型分别计算了它在二氯甲烷(1)、甲醇(2)、气态(3)和乙腈(4)溶液中的吸收和发射光谱.研究结果表明:优化得到的几何结构参数和相应的实验值符合得非常好.在极性较大的溶剂(2和4)中Os—P(1)和Os—C(1)键较长,Os—N(3)键较短,溶剂的极性会影响配合物的电子云分布.配合物在1-4溶剂中的最低能吸收和发射均来自分子轨道68→71的激发,该激发被指认为[d(Os)+π(CN)+π(N^N)→π*(N^N)]的跃迁具有混合的MLCT/LLCT特征.配合物在1-4溶剂中的最低能吸收和发射分别在471,410,488和445nm以及598,536,634和545nm,表明随着溶剂极性的逐渐增大(3〈1〈4〈2),最低能吸收和发射发生明显的蓝移.这显示出通过改变溶剂极性可以调节配合物的发光颜色.
简介:Nanostructuredγ-Al2O3withhighsurfaceareaandmesoporousstructurewassynthesizedbysol-gelmethodandemployedascatalystsupportfornickelcatalystsinmethanereformingwithcarbondioxide.ThepreparedsampleswerecharacterizedbyXRD,N2adsorption-desorption,TPR,TPO,TPH,NH3-TPDandSEMtechniques.TheBETanalysisshowedahighsurfaceareaof204m2g-1andanarrowpore-sizedistributioncenteredatadiameterof5.5nmforcatalystsupport.TheBETresultsrevealedthatadditionoflanthanumoxidetoaluminumoxidedecreasedthespecificsurfacearea.Inaddition,TPRresultsshowedthatadditionoflanthanumoxideincreasedthereducibilityofnickelcatalyst.Thecatalyticevaluationresultsshowedanincreaseinmethaneconversionwithincreasinglanthanumoxideto3mol%andfurtherincreaseinlanthanumcontentdecreasedthecatalyticactivity.TPOanalysisrevealedthatthecokedepositiondecreasedwithincreasinglanthanumoxideto3mol%.SEMandTPHanalysesconfirmedtheformationofwhiskertypecarbonoverthespentcatalysts.AdditionofsteamandO2todryreformingfeedincreasedthemethaneconversionandledtocarbonfreeoperationincombinedprocesses.
简介:CaF2:Ho3+/Yb3+nano-particleswithintensegreenup-conversion(UC)luminescencearesuccessfullysynthesizedviaafacilehydrothermalapproachbyusingNH4FasthefluoridesourceandNa2EDTAasachelatingreagent.PowderXraydiffraction(XRD),transmissionelectronmicroscopy(TEM),fieldemissionscanningelectronmicroscopy(FE-SEM),andUCemissionspectraareusedtocharacterizethestructures,shapes,andluminescentpropertiesofthesamples.TheeffectsfromfluoridesourcesandchelatingreagentsontheformationsofCaF2nano-particlesareinvestigated,andtheformationprocessisalsodeduced.Undertheexcitationofa980-nmlaserdiode,thesampleseachshowagreenup-conversionemissioncenteredat540nmcorrespondingtothe5S2/5F4→5I8transitionsofHo3+.Moreover,theUCmechanismsofHo3+/Yb3+co-dopedCaF2nano-particlesarealsodiscussed.
简介:AnewSnO_2-Fe_2O_3/SWCNTs(single-walledcarbonnanotubes)ternarynanocompositewasfirstsynthesizedbyafacilehydrothermalapproach.SnO_2andFe_2O_3nanoparticles(NPs)werehomogeneouslylocatedonthesurfaceofSWCNTs,asconfirmedbyX-raydiffraction(XRD),transmissionelectronmicroscope(TEM)andenergydispersiveX-rayspectroscopy(EDX).Duetothesynergisticeffectofdifferentcomponents,theassynthesizedSnO_2-Fe_2O_3/SWCNTscompositeasananodematerialforlithium-ionbatteriesexhibitedexcellentelectrochemicalperformancewithahighcapacityof692mAh·g~(-1)whichcouldbemaintainedafter50cyclesat200mA·g~(-1).Evenatahighrateof2000mA·g~(-1),thecapacitywasstillremainedat656mAh·g~(-1).
简介:InthispaperweusedMOF-5andCu3(BTC)2toseparateCO2/CH4andCH4/N2mixturesunderdynamicconditions.Bothmaterialsweresynthesizedandpelletized,thusallowingforameaningfulcharacterizationinviewofprocessscale-up.ThematerialswerecharacterizedbyX-raydiffraction(XRD)andscanningelectronmicroscopy(SEM).Byperformingbreakthroughexperiments,wefoundthatCu3(BTC)2separatedCO2/CH4slightlybetterthanMOF-5.BecausethecrystalstructureofCu3(BTC)2includesunsaturatedaccessiblemetalsitesformedviadehydration,itpredominantlyinteractedwithCO2moleculesandmoreeasilycapturedthem.Conversely,MOF-5withasuitableporesizeseparatedCH4/N2moreefficientlyinourbreakthroughtest.