简介：Hierarchicalsea-urchin-shapedmanganeseoxidemicrospheresweresynthesizedviaatacilemetnoabasedonthereactionbetweenKMnO4andMnSO4inHNO3solutionat50C.Theaveragediameterofthemicrospheresis850nm.Themicrospheresconsistofacoreofdiameterof800nmandnanorodsofwidth50nm.Thenanorodsexistattheedgeofthecore.TheBrunauer-Emmett-Tellersurfaceareaofthesea-urchin-shapedmicrospheresis259.4m2/g.Apossibleformationmechanismofthehierarchicalsea-urchin-shapedmicrospheresisproposed.Thetemperaturefor90%conversionofbenzene(T90%)onthehierarchicalurchin-shapedMnO2microspheresisabout218℃.

简介：Inthisstudy,apoly(etherblockamide)(Pebax1657)compositemembraneappliedforCO2capturewaspreparedbycoatingPebax1657solutiononpolyacrylonitrile(PAN)ultrafiltrationmembrane.Ethanol/watermixturewasusedasthesolventofPebaxandtheeffectsofethanol/watermassratiosandPebaxconcentrationonthepermeationpropertiesofcompositemembranewerestudied.Toenhancethecompositemembranepermeance,thegutterlayer,madefromreactiveaminosiliconecrosslinkingwithpolydimethylsiloxane(PDMS),wasdesigned.Theinfluenceofcrosslinkingdegreeofthegutterlayeronmembraneperformancewasinvestigated.Asaresult,aPebax/aminoPDMS/PANmultilayermembranewithhexaneresistancewasdeveloped,showingCO2permeanceof350GPUandCO2/N2selectivityover50.Theblendofpolyethyleneglycoldimethylether(PEG-DME)withPebaxascoatingmaterialwasstudiedtofurtherimprovethemembraneperformance.AfterbeingcombinedwithPEG-DMEadditive,CO2permeanceofthefinalPebax-PEG-DME/amino-PDMS/PANcompositemembranereached400GPUabovewithCO2/N2selectivityover65.

简介：Weprovideanewclassofinteriorsolutionofa(2+1)-dimensionalanisotropicstarinFinchandSkeaspacetimecorrespondingtotheBTZblackhole.WedevelopthemodelbyconsideringtheMITbagmodelEOSandaparticularansatzforthemetricfunctiongrrproposedbyFinchandSkea[M.R.FinchandJ.E.F.Skea,Class.Quantum.Grav.6(1989)467].Ourmodelisfreefromcentralsingularityandsatisfiesallthephysicalrequirementsfortheacceptabilityofthemodel.

简介：MoleculardynamicssimulationsareperformedtostudythegrowthmechanismofCH4-CO2mixedhydrateinxCO2=75%,xCO2=50%,andxCO2=25%systemsatT=250K,255Kand260K,respectively.OursimulationresultsshowthatthegrowthrateofCH4-CO2mixedhydrateincreasesastheCO2concentrationintheinitialsolutionphaseincreasesandthetemperaturedecreases.Viahydrateformation,thecompositionofCO2inhydratephaseishigherthanthatininitialsolutionphaseandtheencagingcapacityofCO2inhydratesincreaseswiththedecreaseintemperature.ByanalysisofthecageoccupancyratioofCH4moleculesandCO2moleculesinlargecagestosmallcages,wefindthatCO2moleculesarepreferablyencagedintothelargecagesofthehydratecrystalascomparedwithCH4molecules.Interestingly,CH4moleculesandCO2moleculesfrequentlyreplacewitheachotherinsomeparticularcagesitesadjacenttohydrate/solutioninterfaceduringthecrystalgrowthprocess.Thesetwospeciesofguestmoleculeseventuallyacttostabilizethenewlyformedhydrates,withCO2moleculesoccupyinglargecagesandCH4moleculesoccupyingsmallcagesinhydrate.

简介：<正>近几年来,中考对作图的考查也变得多样化,作图题镶嵌于计算、推理、猜想或表述之中,让学生能真切感受到作图的用场.翻开2014以来年的海南中考试题,几乎每套试卷中都有视图与投影的考点.通常主要考查常见立体图形的三视图,由视图确定立方体的个数,及运用视图与投影知识解决生活中的实际问题等.为了帮助同学们更好地做好复习,下面以近年各地中考题为例进行分析,以期能提高大家的复习效率,帮助大家找到这类题型的解决策略.

简介：Inthispaper,weareconcernedwiththeglobalexistenceandconvergenceratesofthesmoothsolutionsforthecompressiblemagnetohydrodynamicequationswithoutheatconductivity,whichisahyperbolic-parabolicsystem.TheglobalsolutionsareobtainedbycombiningthelocalexistenceandaprioriestimatesifH3-normoftheinitialperturbationaroundaconstantstatesissmallenoughanditsL1-normisbounded.Aprioridecay-intimeestimatesonthepressure,velocityandmagneticfieldareusedtogettheuniformboundofentropy.Moreover,theoptimalconvergenceratesarealsoobtained.

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简介：Wereportedabifunctionalmaterial,Cr-salenimplantedconjugatedmicroporouspolymer(Cr-CMP),whichisabletocaptureexcellentCO2amountsandhasaremarkablecatalyticactivitytowardsthecycloadditionreactionofCO2toepoxidesformingcycliccarbonatesatmildconditionswithoutadditionalsolvents.ThisheterogeneousCr-CMPcatalysthasasuperiorcatalyticactivitytoitsrelatedhomogeneouscatalystandcanbereusedmorethantentimeswithoutasignificantdecreaseincatalyticactivity.

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.

简介：研究目的：研究新型磁性回热填料Gd2O2S对液氦温区高频脉管制冷机多级回热器损失特性的影响。创新要点：确定了不同回热填料以及运行参数（频率、平均压力）下液氦温区多级脉管制冷机的制冷温度和各级预冷量，进一步明确了4K高频回热损失机理。研究方法：采用理论研究与实验验证相结合的方法，基于一台两级G-M型低频脉管制冷机预冷的单极斯特林型高频脉管制冷机，研究多级回热器在高频以及4K温区下的损失特性。选取新型回热填料Gd2O2S替代部分回热填料HoCu2，比较回热器采用两种填料时在不吲运行频率及平均压力下的冷端制冷温度（图10）、各级预冷量和预冷温度（图1112）。重要结论：采用孔隙率较小的新型磁性回热填料Gd2O2S可显著改善第一级回热器内压力波与质量流的相位关系，从而减小该级回热损失。减小平均压力可以降低制冷机无负荷制冷温度并减小第二级预冷量，但制冷工质氦的体积比热容会急剧增大，从而使低温级回热器的换热对频率非常敏感。此外，频率对高温级回热器的回热特性影响不明显。该方法可以为三级斯特林型4K多级脉管制冷机提供设计依据。

简介：Westudytheoreticallyhowtoproduceanddetecttheultracoldground-stateCs2moleculefromFeshbachstate.Nu-mericalcalculationsareperformedbysolvingthequantumLiouvilleequationbasedonmultilevelBlochmodel.Theproducingefficiencyreaches55%andthedetectingefficiencyis31%.TheproducinganddetectingefficienciesarecloselyrelatedtotheRabifrequenciesoflaserpulses.Thedecayofrelevantelectronicandvibrationalstatesobviouslyreducestheproducinganddetectingefficiencies.

简介：Letuk(2,r)bealittleq-Schuralgebraoverk,wherekisafieldcontaininganl-thprimitiverootεof1withl≥4even,theauthorconstructsacertainmonomialbaseforlittleq-Schuralgebrauk(2,r).

简介：搭建了一套基于铥钬共掺光纤的激光放大系统，包含1个2μm增益开关主振荡器和一级铥钬共掺光纤放大器。获得了平均功率大于300mw的2txm脉冲输出，放大器平均功率增益达11dB，放大斜率效率达30％，这些性能指标与双包层掺铥光纤放大器相当。输出脉冲重频在40kHz时，最高脉冲能量为7．27μJ，脉宽88ns，对应的峰值功率为82．6W。放大过程中，激光光谱宽度小于0．3nm，边模抑制比大于35dB。

简介：WediscussthenonlinearSchrdingerequationwithvariablecoefficientsin2Dgraded-indexwaveguideswithdifferentdistributedtransversediffractionsandobtainexactbrightanddarksolitonsolutions.Basedonthesesolutions,wemainlyinvestigatethedynamicalbehaviorsofsolitonsinthreedifferentdiffractiondecreasingwaveguideswiththehyperbolic,GaussianandLogarithmicprofiles.Resultsindicatethatforthesameparameters,theamplitudeofbrightsolitonsintheLogarithmicprofileandtheamplitudeofdarksolitonsintheGaussianprofilearebiggestrespectively,andtheamplitudeinthehyperbolicprofileissmallest,whilethewidthofsolitonshastheoppositecase.

简介：Underinvestigationinthispaperisa(3+1)-dimensionalvariable-coefficientKadomtsev–Petviashviliequation,whichdescribesthepropagationofsurfaceandinternalwaterwaves.ByvirtueofthebinaryBellpolynomials,symboliccomputationandauxiliaryindependentvariable,thebilinearforms,solitonsolutions,B¨acklundtransformationsandLaxpairareobtained.Variablecoefficientsoftheequationcanaffectthesolitonicstructure,whentheyarespeciallychosen,whilecurvedandlinearsolitonsareillustrated.Elasticcollisionsbetween/amongtwoandthreesolitonsarediscussed,throughwhichthesolitonskeeptheiroriginalshapesinvariantexceptforsomephaseshifts.

简介：Siliconcarbidefiber/siliconcarbidematrix(SiCf/SiC)compositesareofinterestasafuelcladdingandstructuralmaterialindesignsofadvancednuclearreactorduetotheirsuperiorthermo-mechanicalpropertiesandstabilitiesandlowcross-sectionforneutroncaptureunderthesevereserviceenvironmentincludinghightemperatureandhighenergyneutronbombardment.SiCf/SiCcompositionsconsistsofSiCfiberandSiCmatrixwhichexistinwellover100polymorphsdependentonthevariedstackingofSi-Cclose-packedatomicplanes,2H-SiC,4H-SiC,6H-SiC,3C-SiC,15R-SiC,etc.EnergeticHeatomscanbecreatedandaccumulatedvianuclearreactions.HeatomsagglomerateandcoarsenintoHebubblesandcandeterioratestructuralpropertiesbyinducingcrackandcreep.Inthisexperiment,thedamageofn-type4H-SiCwafers(researchstandard,suppliedbytheCreeResearchInc.)withathicknessof0.38mmimplantedwith100keVHe+toafluenceof31016He+/cm2andpost-implantation-annealedbehavioratdifferenttemperaturewerestudiedusingRamanscatteringspectroscopy.