简介:Achiralrutheniumcomplex[(1S,2S)-DPEN]-RuCl_2(PPh_3)_2(DPEN=1,2-diphenylethylenediamine,PPh_3=triphenylphosphine)wasencapsulatedinthechannelofAl-MCM-41byelectrostaticadsorptionand1,1-dichlorosilacyclobutanemodification.Thepreparedheterogeneouscatalystshowedthesamecatalyticactivityandenantioselectivityasthecorrespondinghomogeneouscatalystintheasymmetrichydrogenationofacetophenone,andcouldbereusedatleastseventimeswithoutsignificantlossofcatalyticactivityandenantioselectivity.
简介:用微波高温固相法合成了Er^3+单掺Lu2O3,Li^+与Er^3+共掺Lu2O3及Li^+,Zn^2+,Mg^2+掺杂Lu2O3∶Er^3+的荧光粉。实验表明金属离子Li^+、Zn^2+、Mg^2+、Er^3+掺杂Lu2O3,不影响Lu2O3的立方晶相。扫描电子显微镜测量表明,Li^+掺杂可以有效改善粉体的分散性和形貌,Li^+,Zn^2+,Mg^2+共掺杂获得的粉体颗粒分布更加均匀,粒径范围为80~100nm。379nm激发下,Li^+与Er^3+共掺样品发光较单掺Er^3+样品在565nm处的发光增强了4.5倍,而Li^+、Zn^2+、Mg^2+与Er^3+共掺样品较其发光增强5.3倍。980nm激发下,Li^+与Er^3+共掺样品,Li^+、Zn^2+、Mg^2+与Er^3+共掺样品的发光分别比单掺Er^3+样品在565nm处发光增强23倍与39倍,在662nm处发光强度分别增强20倍与43倍。379nm激发下,较单掺Er3+的样品,掺杂Li^+的样品和Li^+,Zn^2+,Mg^2+和Er^3+共掺的样品荧光寿命均有所增加,而Zn^2+、Er^3+共掺及Mg^2+、Er^3+共掺样品的荧光寿命则有所缩短。
简介:The2-C,methylenegroupof1-aroyl-1,2-dihydro-3H-naphtho[2,1-b]pyran-3-ones(2)havebeenshowedtopossessasuperiorreactivitytowardsmanyoforganicreagents.Thena-phthopyrones(2)condensedwitharomaticaldehydestogivethe2-arylidinederivatives(3).Bromin-ationof2gave1,2-dibromo(4)or5-bromo(5)derivativesdependingonthereactionconditions.Thebasecatalyzedadditionorcycloadditionofnaphthopyrones(2)to4-methoxybenzalacetophenonegavetheexpectedMichaeladduct(6)orthecyclicadducts(7-9)dependingonthetypeofcatalyticbaseandreactionconditions.Structuresoftheproductshavebeenestablishedbyelementalanalyses,IRand~1HNMRspectroscopicmethods.
简介:Nuclearmassisoneofthefundamentalquantityofatomicnucleus.Thetotalbindingenergyofanucleusderivedfromtherelatedmassvaluesreflectsalltheinteractionsamongtheconstitutingnucleons.Massesofshort-livedA=2Z+3nucleiof112SnprojectilefragmentshavebeenmeasuredattheexperimentalcoolerstorageringCSRe,employingtheIsochronousmassspectrometry(IMS).TheexperimentwasconductedattheHeavyIonResearchFacilityinLanzhouatthebeginningof2016.Theprimarybeamof112Sn35+wasaccumulatedinthesynchrotronCSRmandacceleratedto467.91MeV/u.Secondarybeamwereproducedbyimpingingthehighintensity112Sn35+beamontoa10mmberylliumtargetwhichwaslocatedattheentranceoftheradioactivebeamlineRIBLL2.Theprojectilefragmentsof112Snemergedfromthetargetwerethentransmitted,separatedinflightthroughRIBLL2andfinallyinjectedintoCSRe.
简介:TheepoxidationofallylchloridewithH2O2onTi-ZSM-5preparedbyisomorphoussubstitutionofHZSM-5withTiCl4gaswasstudied.TheresultsshowthatTi-ZSM-5hasahighcatalyticefficiencyfortheepoxidationofallylchloride.TheH2O2utilizationreaches99.50%whentheallylchloride/H2O2molarratiois>1.Theeffectofsolventspecies,catalystconcentration,H2O2andallylchlorideconcentrationandreactiontemperatureontheepoxidationwasinvestigatedsimultaneously.Itisfoundthatmethanolisthebestsolventforthereaction.Thereactionrateequationwithv=k[Cat.][H2O2]1/2-[C3H5Cl]andtheapparentactivationenergywithEa=63.462kJ/molareobtainedaccordingtothekineticsstudy.
简介:Weperformfirst-principlecalculationsforthestudyoftheorthorhombicRb2Cd2(SO4)3structure.Electronicenergybands,totalandpartialdensitiesofstatesarereportedandanalysed.Itisfoundthatoxygenatomic2pelectronsstronglyhybridizewithRb/orCd4dandS2pstates,resultingintwo-typeionicgroupswithweakcouplings.Itisshownthatmacroscopicdomainwallsoriginatefromsuchweak-couplingionicgroups,arisingatthecellboundaries.Theasymmetriccationbonds(Rb-OandCd-O)andthesubsequentrotationsoftheS04tetrahedracanleadtothedrivingforceoftheferroelectricbehaviour.Thepredictedpyroelectriccurrenteffectsareobservedexperimentallyintheferroelectricphase.
简介:研究了YBaCu3O6~7超导催化剂上CO2的加氢制醇反应。考察了温度、压力和空速等条件对催化剂反应性能的影响。反应的主要产物是甲醇、CO和少量甲醚。利用XPS、XRD和AFM等技术对催化剂的结构、铜的存在状态和反应活性位进行表征发现,在反应过程中,YBa2Cu3O6~7由orthombic相转变为tetragonal相。反应活性位可能是Cu(I)物种。反应后催化剂颗粒的分散程度明显提高
简介:Amolybdenumdisulfide(MoS2)saturableabsorberwasfabricatedbythermallydecomposingtheammoniumthiomolybdate.ByusingtheMoS2absorber,acompactdiode-pumpedpassivelyQ-switchedTm:GdVO4laserhasbeendemonstrated.AstableQ-switchedlaserwithrepetitionratesfrom25.58to48.09kHzwasachieved.Maximumaverageoutputpowerwas100mWwiththeshortestpulsedurationof0.8μs.Maximumpulseenergyis2.08μJatcenterof1902nm.
简介:Theroleofpulseparametersonnanoparticlepropertyisinvestigatedself-consistentlybasedonacoupleoffluidmodelandaerosoldynamicsmodelinacapacitivelycoupledparallel-plateacetylene(C2H2)discharge.Inthismodel,themasscontinuityequation,momentumbalanceequation,andenergybalanceequationforneutralgasaretakenintoaccount.Thus,thethermophoreticforceariseswhenagastemperaturegradientexists.Thetypicalresultsofthismodelarepositiveandnegativeiondensities,electronimpactcollisionsrates,nanoparticledensity,andchargedistributions.Thesimulationisperformedfordutyratio0.4/0.7/1.0,aswellaspulsemodulationfrequencyfrom40kHzto2.7MHzforpureC2H2dischargesatapressureof500mTorr.Wefindthatthepulseparameters,especiallythedutyratio,haveagreataffectonthedissociativeattachmentcoefficientandthenegativedensity.Moreimportantly,bydecreasingthedutyratio,nanoparticlesstarttodiffusetothewall.Undertheactionofgasflow,nanoparticledensitypeakiscreatedinfrontofthepulseelectrode,wherethegastemperatureissmaller.
简介:通过对市场结构理论演变过程的回顾,认为以SCP范式为基础的传统市场结构分析框架越来越不适应于当前日益复杂的经济环境。基于此,本文提出了网络型市场结构的概念,分析了网络型市场结构的特征,讨论了网络结构型市场结构的分类,并提出了网络型市场结构的一般模式。接着,构建了网络型寡头垄断市场结构模型,分析了该模型的四个特性。之后,对2×2网络型寡头垄断市场结构存在的八种策略组合进行了合并整理,求出了在现实中经常采用的四种不同的策略组合下的Cournot产量均衡解、价格均衡解以及实现均衡时的利润。最后,通过一个算例对各个Cournot均衡解的特性进行了分析,并比较了四种策略组合的优劣。
简介:TheternaryCu(Ⅱ)complexwith2,2′-bipyridyl(bipy)andL-methioninte(L-Met)hasbeensynthesizedandcharacterizedbyelementalanalysis,molarconductivity,UV-Visspectra,IRspectraandpH-potentiometrictitrationmethods.Thestructureofthecomplex[Cu(L-Met)(bipy)(H2O)]ClO4·3/8H2OwascharacterizedbytheX-raydiffractionanalysis.Itcrystallizesinthetriclinicsystem,spacegroupP1withfourmoleculesinaunitcellofdimensions,a=0.7656(2)nm,b=1.3142(3)nm,c=2.0596(4)nm,α=97.70(3)°,β=97.96(3)°,γ=94.33(3)°,V=2.0244(8)nm^3,R1=0.0441andwR2=0.0678,Thecrystalcontainsfourcrystallographicallyindependent[Cu(L-Met)(bipy)(H2O)]^+complexes(Cu1-Cu4),havingadistortedsquare-pyramidalgeometrywiththesamecoordinatedatomsaroundeachcoppercenter.Thebaseplaneisoccupiedbytwonitrogenatomsofonebipy,theaminonitrogenatomandonecarboxylateoxygenatomfromeachindependentL-Metmoiety,andonewateroxygenatanaxialposition.CulandCu3areessentiallyenantiomersofCu2andCu4.Thefourmoleculesarepackedwitheachotherbyintermolecularhydrogen-bondingandaromatic-ringstackinginteractions.
简介:Variousenolsof2-acylmethyl-4,4-dimethyl-2-oxazolineswerepreparedinmoderateyieldsviaultrasonicallycatalyzedreactionsof2,4,4-trimethyl-2-oxazolinewitharenecarboxylicestersinthepresenceofUDP-t-BuCl-i-Pr2NHsystem.
简介:Thepaperdealswiththeinfluenceofanodematerialontheefficiencyofdegradationfororganicpollutantsinwatersystem.Theelectrochemicalperformanceoffluorineiondopedleaddioxide(F--PbO2)electrodeforthedegradationofanilinewascomparedwiththatofundopedleaddioxide(PbO2)electrodebyultraviolet-visible(UV-Vis)spectroscopy,linearvoltammetryandotheranalyticalmethods,suchasthemeasurementbychemicaloxygendemandanalyzer,highperformanceliquidchromatographyandscanningelectronmicrography.ItwasshownthatbothPbO2electrodeandF--PbO2electrodecouldmakeanilinebemineralizedcompletelyandhavethesamedegradationcourse,butF--PbO2electrodehasmuchhigherelectrocatalyticactivitythanundopedPbO2electrodefortheelectrochemicaldegradationofaniline.TheexperimentalresultsconfirmthatF--PbO2electrodehasmuchhigherpotentialforoxygenevolutionthanundopedPbO2electrode.
简介:Thenotionofmultibandsuperconductivitywithdominanttwo-gapfeatureshasbeenrecentlyappliedtotheunconventionalsuperconductorCeCu2Si2forchallengingthepreviouslyacceptedconceptofnodald-wavepairing.Intheproposedstudy,therealisticmultibandFermisurfacetopologyofCeCu2Si2wasobtainedthroughfirst-principlescalculations,andanalysiswasconductedwithaneffectivetwo-bandhybridizationmodelincludingdetailedbandstructure.WithintheT-matrixapproximation,theobtainedcalculationresultsshowthatdifferentpairingcandidates,includingfullygappeds-wave,loop-nodals-wave,andd-wavepairings,couldyieldqualitativelydistinctfeaturescharacterizedbyimpurity-inducedboundstates.Thesefeaturescanbeverifiedthroughhigh-resolutionscanningtunnelingmicroscopyorspectroscopyandprovidecorroborativejustificationthatwouldbebeneficialfortheongoingresearchregardingthesuperconductinggapsymmetryofCeCu2Si2atambientpressure.
简介:Lifetimemeasurementsoflow-lyingexcitedstatesin^87Zrhavebeenperformedviaβ-γcoincidences.The127MeV^32SbeamwasdeliveredfromtheSector-FocusingCyclotron(SFC)oftheHeavyIonResearchFacilityinLanzhou(HIRFL).Theparentnuclei^87Nbwereproducedbythereaction58Ni(32S,2p1n),atabeamenergy127MeVthrougha8umAldegrader.A200ug/cm^2layerof58Nievaporatedontoa200ug/cm^2thickcarbonfoilwasemployedasthetarget.Afterevaporationresidueswereseparatedfromtheprojectilebeamsbythegas-filledrecoilseparatorSHANS[1],thenucleiofinterest87Zrcanbeobtainedwithahigherpurityandthenwereimplantedintoa300umsilicondetector.