简介:TheapplicationofLanthanumBromide(LaBr3)detectorsprovidesauniqueopportunitytomeasurelifetimeofexcitedstatesinpicosecond-nanosecondregion.Reducingthebackgroundisofcriticalimportancetogetpreciseresults.Forsomeexcitedstatesfeedingfromisomerswithlifetimelongerthan1μs,itcanbeachievedbytheSpectrometerforHeavyAtomandNuclearStructure(SHANS)[1].143Eunucleiwerepopulatedviathe123Sb(24Mg,4n)fusion-evaporationreaction.Mostoftheevaporationresiduesatgroundstateorlong-livedisomersweretransferredtodetectionterminalafteraflightofabout1.4μsinSHANS.Inthecaseof143Eu,threetransitionshavebeenobserved(Fig.1).
简介:Thenatureofresistivetransitionofhigh-qualitycrystallinethinfilmsofYBa2Cu3O7-δhasbeenstudiedundermagneticfields(H)appliedalongthecdirectionoverawiderangeofdopedholes,p,intheCuO2planes.Thefield-andtemperature-dependentin-planeresistivity,ρab(T,H),hasbeenanalyzedwithinthethermallyassistedflux-flow(TAFF)formalism.Thefluxactivationenergy,U(T,H),hasbeenextractedfromthisanalysis.Thelow-Tpartoftheρab(T,H)datacanbedescribedbyanactivationenergyhavingthefunctionalformofU(T,H)=(1-t)m(H-0/H)β,wheret=T/Tc(reducedtemperature),andH0isafieldscalethatprimarilydeterminesthemagnitudeofU(T,H).Thetemperatureexponent,m,showsasystematicvariationwithp,whereasthefieldexponent,β,isinsensitivetothepvaluesandisclosetounity.TheH0,ontheotherhand,changesrapidlyaspisvaried.U(T,H)islinkedtothepinningpotentialandconsequentlyonthesuperconductingcondensationenergy.Sincethenormalstatepseudogapdirectlyaffectssuperconductingcondensationenergy,aclearcorrespondencebetweenH0andthePGenergyscale,εg,isfound.Possibleimplicationsoftheseresultsarediscussed.
简介:Theeffectsofcarbon-ionirradiationoncancercelltelomerefunctionhavenotbeencomprehensivelystudied[1].Ourpreviousreportshowedthatcancercellswithtelomeredysfunctionweremoresensitivetocarbon-ionirradiation,butthemechanismthatlinktelomeredysfunctionandcancercellinactivationhasnotbeeninvestigated.
简介:YBa2Cu3Ox(YBCO)thinfilmsgrownondifferentsubstrateswithand/orwithoutEu2CuO4(ECO)bufferlayerwereinvestigatedbyX-raywideanglediffraction,reflection,diffusescatteringandtopography.TheresultsshowthatfortheyttriastabilizedZrO2(YSZ)substrate,thepresenceofanECObufferlayerimprovesthecrystallinequalityoftheYBCOfilm,whileanegativeeffectisobservedfortheSrTiO3(STO)substrate.ThelateralcorrelationlengthforasamplegrownonaYSZsubstratewithECObufferLayerismuchgreaterthangrownonanSTOsubetrate.TheSTOsubstrateusedhasmosaicstructure.2001ElsevierScienceB.V.Allrightsreserved.
简介:Theequilibriumgeometries,relativestabilities,andelectronicpropertiesofMnAgm(M=Na,Li;n+m≤7)aswellaspureAgn,Nan,Lin(n≤7)clustersaresystematicallyinvestigatedbymeansofthedensityfunctionaltheory.Theoptimizedgeometriesrevealthatfor2≤n≤7,therearesignificantsimilaritiesingeometryamongpureAgn,Nan,andLinclusters,andthetransitionsfromplanartothree-dimensionalconfigurationsoccuratn=7,7,and6,respectively.Incontrast,thefirstthree-dimensional(3D)structuresareobservedatn+m=5forbothNanAgmandLinAgmclusters.Whenn+m≥5,astrikingfeatureisthatthetrigonalbipyramidbecomesthemainsubunitofLinAgm.Furthermore,dramaticodd-evenalternativebehavioursareobtainedinthefragmentationenergies,secondorderdifferenceenergies,highestoccupiedandlowestunoccupiedmolecularorbitalenergygaps,andchemicalhardnessforbothpureanddopedclusters.Theanalyticresultsexhibitthatclusterswithanevenelectronicconfiguration(2,4,6)possesstheweakestchemicalreactivityandmoreenhancedstability.