学科分类
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64 个结果
  • 简介:Supernova(SN)neutrinosdetectedontheEartharesubjecttotheshockwaveeffects,theMikheyev–Smirnov–Wolfenstein(MSW)effects,theneutrinocollectiveeffectsandtheEarthmattereffects.Consideringtherecentexperimentalresultaboutthelargemixingangleθ13(■8.8°)providedbytheDayaBayCollaborationandapplyingtheavailableknowledgefortheneutrinoconversionprobabilityinthehighresonanceregionofSN,PH,whichisintheformofhypergeometricfunctioninthecaseoflargeθ13,wededucetheexpressionofPHtakingintoaccounttheshockwaveeffects.ItisfoundthatPHisnotzeroinacertainrangeoftimeduetotheshockwaveeffects.Afterconsideringallthefourphysicaleffectsandscanningrelevantparameters,wecalculatetheeventnumbersofSNneutrinosforthe"Garching"distributionofneutrinoenergyspectrum.Fromthenumericalresults,itisfoundthatthebehaviorsofneutrinoeventnumbersdetectedontheEarthdependontheneutrinomasshierarchyandneutrinospectrumparametersincludingthedimensionlesspinchingparameterβα(whereαreferstoneutrinoflavor),theaverageenergy,andtheSNneutrinoluminositiesLα.Finally,wegivetherangesofSNneutrinoeventnumbersthatwillbedetectedattheDayaBayexperiment.

  • 标签: 超新星中微子 地球 探测 超几何函数 无量纲参数 冲击波
  • 简介:Thereactionmechanismsofdienepolymerizationwithhomogeneousrareearthcatalystarestudiedbymeansofthespectraof1H-NMR,one-andtwo-dimensions13C-NMR.BasedonthedataofaboveNMRspectra,itisproposedthatthepolymerizationreactionproceedsaccordingtothefollowingmechanism:η4-diene(cis-(?)trans-)andη3-allyl(syn-(?)anti-).

  • 标签: Reaction mechanism DIENE COORDINATION POLYMERIZATION HOMOGENEOUS
  • 简介:Theresearchworkonpreparationprocessofactivematerialsoftherareearthionselectiveelectrodesandthevalenceoftheelectrodemembranewerereported.Theactivematerialswerechacterizedbyinfraredspectrum,elementalanalysisandXPS.Wehadstudiedtherareearthionselectiveelectrodesinwhichtheactivematerialsconsistoffunctionalpolymers.Inthispaper,theresearchworkonpreparationprocessandthevalenceoftheelectrodemembranewerereported,whichhasnotbeenseeninliteratureyet.

  • 标签: 活性物质 稀土离子选择电极 电极隔膜 化合价
  • 简介:Theself-diffusionofEu^3+ioninporousresinsD72andD751wasstudiedbyisotopeexchangereaction.ApplyingKataoka'sbidisperseporemodel,theintraparticleeffectivediffusivityDewereresolvedintoasoliddiffusivityDgandamacroporediffusivityDp.TheexperimentsshowthatDe.DpandDgallincreasewiththeincreaseofreactiontemperature;theresponseDpandDgofD751resinissmallerthanthatofD72resin;thediffusivityofEu^3+ioninsolutionislargerthanDp,whichleadstotheconclusionthatthediffusionofionintheporeofresincannotcompletelybeequaltothatinsolution.

  • 标签: 稀土金属离子 多孔物质离子 树脂
  • 简介:DrivenbycuriosityaboutpossibleflightoptionsfortheChang’e-2spacecraftafteritremainsattheSun-EarthL2point,effectiveapproachesweredevelopedfordesigningpreliminaryfuel-optimalnear-Earthasteroidflybytrajectories.Theapproachesincludetheuseofmodifiedunstablemanifolds,gridsearchofthemanifolds’parameters,andatwo-impulsemaneuverfororbitalphasematchingandz-axisbiaschange,andaredemonstratedtobeeffectiveinasteroidtargetscreeningandtrajectoryoptimization.Asteroidflybysareexpectedtobewithinadistanceof2×107kmfromtheEarthowingtotheconstrainedEarth-spacecraftcommunicationrange.Inthiscase,thespacecraft’sorbitalmotionissignificantlyaffectedbythegravitiesofboththeSunandtheEarth,andtherefore,theconceptofthe"heliocentricoscillating-Keplerorbit"isproposed,becausetheclassicalorbitalelementsoftheflybytrajectoriesreferencedintheheliocentricinertialframeoscillatesignificantlywithrespecttotime.Theanalysisandresultspresentedinthisstudyshowthat,amongtheasteroidswhoseorbitsarethemostaccuratelypredicted,"Toutatis","2005NZ6",or"2010CL19"mightbeencounteredbyChang’e-2inlate2012or2013withtotalimpulseslessthan100m/s.

  • 标签: 近地小行星 飞行轨迹 地球 太阳 轨道运动 不稳定流形
  • 简介:Thetetravalentmetalsaltsofmonoalkylphosphates[M(R-OPO3)2]areanewkindofstationaryphasesofchromatography-homogeneousbondedphases.Thestudiesonpreparation,structureandgaschromatographicefficiencyofceriumbis(octylphosphate)(COPP)arereportedinthispaper.Byusingchemicalanalysis,infraredspectra,x-raydiffractionanalysis,thestrongevidencethatCOPPhasalayeredstructureoftheα-zirconiumphosphatetypewasdemonstrated,therepetitiveunitisC8H17OPO3CeO3POC8H17andthereisalittlebendingorinterpenetrationofthealkylchainswithinthelayers.ThethermogravimeticanalysisoftheCOPPindicatedthatithasmuchmorethermalstabilitythansilica-basedpackings.ThethermodynamicparametersΔHandmolecularconnectivityindexesx′fortheadsorptionofseveraldozencompoundsontheCOPPhavealsobeendeterminedbygaschromatographicmethod,andthefinelinearitybetweenthemwasshown.

  • 标签: 有机轻元素吸附剂 稀土元素吸附剂 二辛基磷酸铈
  • 简介:Thecopolymerizationofl-octenewithstyrenecatalyzedbyrareearthcoordinationcatalystshasbeenstudiedforthefirsttime.Somefeaturesandkineticbehavioraredescribed.Theoverallactivationenergyofthecopolymerizationwas22.2KJ/molandthecopolymerizationratecouldbeexpressedasRp=Kp[Nd][M]2.(=1.68×10-3L2/mol2.S,50℃,[Oct]/[St]=1).ThecatalyticactivityofvariousrareearthelementsinLn(naph)3forthecopolymerizationwascomparedandshowsthefollowingsequence:Dy,Y,Yb>Ho>Sm,Gd,Nd>Pr>Ce>La>Tm.Bothmonomersofl-octeneandstyreneinthecopolymerizationbyNd(naph)3-AlEt3havethetendencyofconstantproportioncopolymerization.Thestructureofthecopolymerswasstudiedby1H-NMR.

  • 标签: 1-OCTENE STYRENE COPOLYMERIZATION Rare earth catalyst
  • 简介:AnovelSchiffbase(TAMET)wassynthesizedbythecondensationoftetraglycolaldehydewithmethionineandamildoxidantCrO3·(C5H5N)2wasselectedforthereaction.SevennewrareearthcomplexeswiththisSchiffbasehavebeensynthesizedandcharacterizedbyelementalanalysis,TG-DTA,molarconductivity,magneticsusceptibilityandIR,especially1HNMRspectra.Informationwasobtainedfromreflectancespectraandthecoordinationofsulfuratomtorareearthswasdiscussed.TheexperimentalresultsshowthatthesecompoundshavesomebiologicalactivityandcoulddisposeofO2.

  • 标签: Novel SCHIFF base noncyclic POLYETHER rare
  • 简介:稳定的几何学,电子结构,和磁性(8,0)并且(4,4)做与的围单人赛的BNnanotubes(BNNT)稀土元素(RE)原子与密度用第一原则的pseudopotential飞机波浪方法被调查功能的理论(DFT)。结果证明这些RE原子能有效地与有利精力在BNNT被做。因为弯曲效果,为RE-atomdoped(4,4)BNNT的有约束力的精力的价值比一样的原子在上的那些大(8,0)BNNT。在RE-5d,6s,和B-2p之间的电子转移,N-2porbitals也被观察。而且,BNNT的电子结构和磁性能被如此的做修改。结果证明Ce,下午,Sm,和Eu原子的吸附能导致磁化,当当BNNT与La被做时,没有磁力被观察时。这些结果为spintronics应用程序并且为开发磁性的nanostructures是有用的。

  • 标签: 氮化硼纳米管 稀土原子 掺杂改性 电子结构 磁性能 赝势平面波方法
  • 简介:Thispaperappliesthestochasticfiniteelementmethodtoanalysethestatisticsofstressesinearthdamsandassessthesafetyandreliabilityofthedams.Formulationsofthestochasticfiniteelementmethodarebrieflyreviewedandtheprocedureforassessingdam’sstrengthandstabilityisdescribed.Asanexample,adetailedanalysisforanactualdam-Nululindamisperformed.Apracticalmethodforstudyingbuilt-damsbasedontheprototypeobservationdataisdescribed.

  • 标签: STOCHASTIC FEM
  • 简介:Theisothermsforsorptionoffulvicacidfromweatheredcoal,andthedistributionratios,Rd,of^169YbatvariousconcentrationoffulvicacidonNa-bentoniteandNa-Kaolinitehavebeenmeasured.Meantime,thedependencesofRdof^169YbonpHvaluesataconstantinitialconcentrationofFAwereobtained.Itwasnotfoundthattheparallelrelationshipbetweenthehighaffinityofhumicsubstancetotheclayandthehighuptakeofmetalwhichhasstrongabilitytocomplexwiththishumicsubstance.

  • 标签: 腐殖质 吸附作用 稀土元素 高岭石表面 膨润土表面
  • 简介:OxidativeDehydrogenationofIsobutanetoIsobutyleneoverF ̄-ModifiedRareEarthMetalOxideCatalystsZHANGWei-de,TANGDing-liang,LAIWen-...

  • 标签: OXIDATIVE DEHYDROGENATION Isobutance RARE EARTH CATALYSTS
  • 简介:Recently,bismuthsulfide(Bi2S3)hasattractedmuchattentioninthethermoelectriccommunityowingtoitsabundance,lowcost,andadvancedproperties.However,itspoorelectricaltransportpropertieshavepreventedBi2S3devicesfromrealizinghighthermoelectricperformance.Inthiswork,ourmotivationistodecreasethelargeelectricalresistivity,whichisrecognizedastheoriginofthelowZTvalueinundopedBi2S3.Wecombinedmeltingandsparkplasmasintering(SPS)inacontinuousfabricationprocesstoproduceBi2S3–xSex(x=0,0.09,0.15,0.21)andBi2S2.85–ySe0.15Cly(y=0.0015,0.0045,0.0075,0.015,0.03)samples.OurresultsshowthatSealloyingatSsitescannarrowthebandgapandactivateintrinsicelectronconduction,leadingtoahighpowerfactorof~2.0μW·cm–1·K–2atroomtemperatureinBi2S2.85S0.15,about100timeshigherthanthatofundopedBi2S3.Moreover,ourfurtherintroductionofClatomsintotheSsitesresultedinasecond-stageoptimizationofcarrierconcentrationandsimultaneouslyreducedthelatticethermalconductivity,whichcontributedtoahighZTvalueof~0.6at723KforBi2S2.835Se0.15Cl0.015.OurresultsindicatethathighthermoelectricperformancecouldberealizedinBi2S3withearth-abundantandlow-costelements.

  • 标签: THERMOELECTRIC BI2S3 CARRIER concentration LATTICE thermal
  • 简介:稀土元素aryloxides由各种各样的烷基组代替了[行(浆)3]例如甲基,isopropyl和tertbutyl,被用作单个部件催化剂影响L减水乳酸(LLA)的戒指洞聚合。催化活动,聚合特征,聚合动力学和机制被学习。稀土元素aryloxides的催化活动被结构和烷基组的数字在苯基戒指上影响,这被发现。越强壮烷基组的电子捐赠能力,催化活动将是越多higher。代用品组的数字的增加将导致一项更高催化的活动。镧tris(2,4,6-tri-tert-butylphenolate)[La(OTTBP)3]在所有镧aryloxides之中展出最高的活动。根据1H-NMR数据,LLA聚合经由包含减水乳酸的酰氧债券的劈开的协作插入机制继续了,这被建议。关键词戒指洞聚合-L减水乳酸-稀土元素aryloxides这个工作被山西省(号码2006011069)的自然科学基础和山西省(号码2009011059-7)的关键实验室的开的基础支持。

  • 标签: 聚合反应动力学 环烷基 稀土 开环 催化活性 乳酸
  • 简介:Arareearthcoordinationsystemwasfirstinvestigatedasanewtypeofcatalystforthering-openingpolymerizationofα-aminoacidN-carboxyanhydrides(NCAs).Theresultsforthepolymerizationofγ-stearyl-α,L-glutamate(SLG)NCAusingneodymiumacetylacetonate(Nd(acac)3)-orneodymiumtris(2-ethylhexylphosphonate)(Nd(P204)3)-triethylaluminum-waterascatalystswerecomparedwiththoseusingconventionalcatalysts.Itwasfoundthatthehelicalpoly(γ-stearyl-L-glutamate)withhighmolecularweightaswellasnarrowmolecularweightdistributioncanbeobtainedinthepresenceofNd(acac)3/AlEt3-1/2H2O.ThepolymerobtainedwascharacterizedbyIRandNMRspectroscopy.

  • 标签: Rare earth COORDINATION catalyst RING-OPENING POLYMERIZATION