学科分类
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60 个结果
  • 简介:Veryrecently,BelleannouncedtheirobservationofΥ(5S)!bJ!(J=0;1;2),indicatingthattheΥ(5S)!bJ!decaysalsohavelargedecaywidths,i.e.,themeasuredbranchratiosofΥ(5S)!bJ!are<3:410??3,(1:640:23+0:30??0:22)10??3,and(0:570:220:07)10??3withJ=0;1;2,respectively[1].ItshouldbenoticedthateventhoughthetreelevelcontributionstoΥ(5S)!bJ!(J=0;1;2)shouldbestronglysuppressedduetotheOkubo-Zweig-Iizuka(OZI)rule,suchlargedecaywidthsareobserved,whichagaininspiresourinterestinunderstandingsuchquantities.Inthiswork,weproposethatthecontributionfromthehadronicloopshouldbeconsideredinstudyingΥ(5S)!bJ!.

  • 标签: LOOP LOOP BE OUR IT
  • 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.

  • 标签: BTC CO2 混合物 分离 扫描电子显微镜 X射线衍射
  • 简介:DarkMatterParticleExplorer(DAMPE)isapowerfulspacetelescopeforhighenergycosmicraysdetectionsuchas-ray,electronandheavyions.ThemainmotivationofDAMPEistofindtheevidenceofdarkmatterexistence,andthesatelliteisscheduledforlaunchingbeforetheendof2015.ThePlasticScintillatorDetector(PSD),whichisoneofthekeycomponentsoftheDAMPEsystem,hastwomajorfunctionalities:distinguishphotonsfromchargedparticlesbyanti-coincidenceandmeasurethechargeofheavyions.ThePSDisdesignedandfabricatedbytheinstituteofmodernphysics,CAS.Itconsistsof82plasticscintillatorstrips,eachofwhichisreadoutbyPMTatbothends,andadouble-dynodereadoutschemeforPMTisutilizedinordertocoverthelargedynamicrange(fromHtoCa).

  • 标签: BEAM TEST PSD
  • 简介:π-/π+ratiowasfoundtobeasensitiveprobetothehigh-densitybehaviorofthesymmetryenergybyusingseveraltransportmodels.However,asshowninFig.1,atbeamenergiesbelowthepionproductionthreshold,theeffectsofin-mediumnucleon-nucleonscatteringcrosssection(whichisstillcontroversial)stronglyaffectthevalueofπ??/π+ratio[1].Itisthusnecessarytodoacomparativestudyoftheeffectsofthein-mediumNNcrosssectionandtheeffectsofthesymmetryenergyonpionproductioninheavy-ioncollisionsatlowerbeamenergies.

  • 标签: NUCLEAR SYMMETRY ENERGY
  • 简介:Thereisagrowingsupportforthelowlyingscalarmesonsf0(500),f0(980),a0(980),and(800)tobegenerateddynamicallyfromtheinteractionofpseudoscalarmesons,whilethecaseofthenextsetofscalarresonancesathigherenergies,f0(1370),f0(1710),K0(1430)ismoreaquestionofdebate.Soisthecaseofthetensorresonancesf2(1270),f′2(1525),K2(1430).AnewperspectiveonthesestateshasbeenofferedinRef.[1]wherethef0(1370)andf2(1270)resonancesareshowntobegeneratedfromtheinteractionprovidedbythelocalhiddengaugeLagrangiansimplementingunitarization.Itisshownthattheideaofthenatureofthesestatesasvectormeson-vectormesoncompositestateshasbeentestedinmanyreactions.Yet,thepermanentdiscussionoftheissuedemandsextrachecksforotherobservablesand,inthissense,theweakdecaysbringanewsourceofvaluableinformationthatshouldservetotestdifferentmodels.

  • 标签: J/Ψ source case SENSE NEXT IDEA
  • 简介:Underinvestigationinthispaperisa(3+1)-dimensionalvariable-coefficientKadomtsev–Petviashviliequation,whichdescribesthepropagationofsurfaceandinternalwaterwaves.ByvirtueofthebinaryBellpolynomials,symboliccomputationandauxiliaryindependentvariable,thebilinearforms,solitonsolutions,B¨acklundtransformationsandLaxpairareobtained.Variablecoefficientsoftheequationcanaffectthesolitonicstructure,whentheyarespeciallychosen,whilecurvedandlinearsolitonsareillustrated.Elasticcollisionsbetween/amongtwoandthreesolitonsarediscussed,throughwhichthesolitonskeeptheiroriginalshapesinvariantexceptforsomephaseshifts.

  • 标签: LAX对 变系数 孤立波解 方程 BACKLUND变换 双线性形式
  • 简介:Thestudyofnucleonresonanceisanimportanttopicinhadronphysics.Themostimportantwaytostudythenucleonresonancesisthecollisionofthephotonandnucleon.Uptonow,theknowledgeaboutthenucleonresonancesaround2GeVisstillscarce.Recently,theCLASCollaborationatJeffersonNationalAcceleratorFacilityreleasedtheirexclusivephotoproductioncrosssectionsfortheΛ(1520),Σ0(1385)andΛ(1405)forenergiesfromnearthresholduptoacenterofmassenergyWof2.85GeVwithlargerangeoftheKproductionangle[1].SincethethresholdforthephotoproductionofΛ(1520)isabout2.01GeV,thenewexperimentaldatawithhighprecisionreleasedbytheCLASCollaborationprovideanopportunitytostudythenucleonresonancesabove2GeV.

  • 标签: EXPERIMENTAL ACCELERATOR PHOTON RANGE MOST is
  • 简介:AseriesofZSM-5zeolites,withthemorphologiesofsphere,spherewithcubicparticlesonthesurface,andcubicparticles,weresynthesizedbyhydrothermalmethodusingn-butylamineasthetemplate,assistedbytheadditionofNaClandcrystalseed.X-raydiffraction(XRD),scanningelectronmicroscope(SEM),X-rayfluorescence(XRF)andtemperature-programmeddesorptionofammonia(NH3-TPD)wereusedtocharacterizethesesamples.Thesamplesweretestedwithtoluenemethylationreaction.Themodifiedsamplecomposedofsphericalparticleswith3μmcrystalparticlesonthesurfacehadapara-xyleneselectivityof95%andmaintained79%oftheinitialconversionafterrunningthereactionfor50h.Thismodifiedsampleshowedthebeststabilityamongthetestedthreemodifiedsamples.

  • 标签: ZSM-5沸石 烷基化反应 对二甲苯 催化性能 扫描电子显微镜 NH3-TPD
  • 简介:Morelocalizedenergydepositionisabletobeproducedinantiproton-nucleuscollisionsincomparisonwithheavy-ioncollisionsduetoannihilationreactions.Searchingforthecoldquark-gluonplasma(QGP)withantiprotonbeamshasbeenconsideredasahottopicbothinexperimentsandinthereticalcalculationsoverthepastseveraldecades.Strangenessproductionandhypernucleusformationinantiproton-inducednuclearreactionsareimportanceinexploringthehyperon(antihyperon)-nucleon(HN)potentialandtheantinucleon-nucleoninteraction,whichhavebeenhottopicsintheforthcomingexperimentsatPANDAinGermany.

  • 标签: STRANGENESS PRODUCTION ANTIPROTON
  • 简介:TheexternalsurfaceofHZSM-5zeolitewaspassivatedbyliquidsiliceousdepositionandbyacidicsitespoisoningwithlepidine,respectively.Thenmethanol-to-hydrocarbons(MTH)reactionwasinvestigatedovertheaboveas-preparedcatalystsandthedissolublecokeontheseusedcatalystswasanalyzedbyGC-MS,tostudytheroleoftheexternalsurfaceofHZSM-5inthecatalyticreaction.ComparisonwiththeexperimentalresultsbasedonparentZSM-5showedthattheproductdistributionofMTHreactionwasobviouslyinfluencedbytheexternalsurface.Evidenceswerelistedasfollows:(1)thefinalproductonparentHZSM-5showedhigheraromaticselectivity,lowerolefinselectivity,lowerratioofC2/C3+aliphaticsandhigherratioofC3/C4+aliphaticsthanthereactionmixtureproducedbythesolecatalysisofacidicsitesinHZSM-5channel;(2)alittleofpentamethylbenzeneandhexamethylbenzeneintheproductonparentHZSM-5,wasproducedviamulti-methylationofmethylbenzeneontheexternalsurface.TheaboveconclusionmayalsobesuitableforMTHreactionoverotherzeoliteswith10-ringchannel.

  • 标签: HZSM-5沸石 产品分布 外表面 芳烃 甲醇 催化反应
  • 简介:Fractionalpyrolysisandone-steppyrolysisofnaturalalgaeCyanobacteriafromTaihuLakewerecomparativelystudiedfrom200to500°C.One-steppyrolysisproducedbio-oilwithcomplexcompositionandlowhighheatingvalue(HHV30.9MJ/kg).FractionalpyrolysisseparatedthedegradationofdifferentcomponentsinCyanobacteriaandimprovedtheselectivitytoproductsinbio-oil.Thatis,acidsat200°C,amidesandacidsat300°C,phenolsandnitrilesat400°C,andphenolsat500°C,weregotasmainproducts,respectively.HZSM-5couldpromotethedehydration,crackingandaromatizationofpyrolyticintermediatesinfractionalpyrolysis.AtoptimalHZSM-5catalystdosageof1.0g,theselectivitytoproductsandthequalityofbio-oilwereimprovedobviously.Themainproductsinbio-oilchangedtonitriles(47.2%)at300°C,indoles(51.3%)andphenols(36.3%)at400°C.Theoxygencontentwasreducedto7.2wt%and9.4wt%,andtheHHVwasraisedto38.1and37.3MJ/kgat300and400°C,respectively.Fractionalcatalyticpyrolysiswasproposedtobeanefficientmethodnotonlytoprovideapotentialsolutionforalleviatingenvironmentalpressurefromwaterblooms,butalsotoimprovetheselectivitytoproductsandobtainhighqualitybio-oil.

  • 标签: HZSM-5催化剂 蓝藻水华 生物油 热解 品质 小数
  • 简介:Inthisreport,wepresentasimulatedresultontheion-massindependenceoftheguidedtransmission,whichisinagreementwiththepreviousexperimentalresults[1].Inordertosearchtheinuenceoftheionmassonguidedtransmission,variousspeciesofionsusedasprojectilesinsimulations.Fig.1showsthetransmissionfractionsforNe7+,Ar7+,Kr7+,andXe7+ions.Thesedatawereacquiredfortiltangleof2inenergyof7keV.Itisseenthatallofionfractionsgraduallyrisesafteratimedelay,andnallyreachstable.

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

  • 标签: 分子动力学模拟 水合物 CO2 CH4 混合 二氧化碳浓度
  • 简介:Highenergyprotonbeamhasthelongpenetrationlengthinsolidmatteranditcouldproducetheradiographsandindicatethetomographyandmaterialpropertiesinsideofthespecimen.Consideringtheexpensivecoststoconstructahighenergyprotonaccelerator,theothercandidateofhighenergyelectronbeambecomesmoreacceptable[1??3].Duetothehighspatialandtemperalresolutionofhighenergyelectronbeam.Itisapowertooltodiagnosetheinnerstructurechangeduringthehighenergydensitymatterproductionandtheinertialconfinementfusionprocess.Inordertostudythedensityresolutionofthehighenergyelectronbeamradiography,astep-targetwasdesignedandproduced.ThestructureandthetargetpicturesareshowninFig.1andtheSitargetswithdifferentslot-widthwereproducedbyusingthemicroetchtechnics.

  • 标签: DESIGN ENERGY ELECTRON
  • 简介:TemperatureisoneofthekeythermodynamicparametersofHEDmatter.Asapopulartechnique,thepyrometerofnarrow-bandlterstogetherwithphotodiodes(namelymulti-channelpyrometer)hasbeenapplied.However,thepyrometercanonlymeasureone-positiontemperatureinsingleshot[1;2].Actually,itisveryimportanttoknowtemperatureevolutionofmultiplepositionsinsingleshot,especiallyforthetargetinducedbyheavyionbeam,wherealargevolumeofHEDmattercanbegenerated.Consequently,afastnew-typepyrometerhasbeendesigned.

  • 标签: MEASUREMENT SPATIAL TEMPORAL
  • 简介:Thedeuteronisalooselyboundstateoftwonucleons.Itisnaturaltoexpectotherboundstatescomposedoftwohadrons,thatis,hadronicmolecularstates[1].AftertheobservationbytheBelleCollaboration,theX(3872)wasrelatedtoalooselyboundstateofDˉDimmediatelyduetothefactthatitsmassisneartheDˉDthreshold.Recently,theBelleCollaborationannouncedtwochargedbottomonium-likestructuresZb(10610)andZb(10650)neartheBˉBandBˉBthresholds[2].TheanalysisoftheangulardistributionindicatedbothZb(10610)andZb(10650)favorIG(JP)=1+(1+).AstructureZc(3900)closetotheDˉDthresholdwasalsoobservedbytheBESIIIcollaborationinthedecayofY(4260),Y(4260)!+??J=[3].

  • 标签: Bethe-salpter EQUATION APPROACH
  • 简介:Grapheneistwodimensionalmaterialswhichismadeofhoneycombedcarbonatoms.Itattractsextensiveinterestsforitswonderfulcharacteristicsthatmakethegrapheneapotentialcandidateinfieldsofmicroelectronicsproduction,moleculedetection,desalinationandDNAsequencing.Highlychargedion(HCI)hashugepotentialenergyforpeelingoffelectrons.Wheninteractingwithsolidsurface,theHCIdistortedthesolidlatticeviapotentialdepositionandthenthenanostructureswereformedonthesolidsurface.TheHCIwasexpectedasatoolforsurfacemodification.Inthiswork,HOPGandgraphemewereirradiatedwithXeq+andArq+ions.ThetypicalRamanspectraofgrapheneandHOPGirradiatedwithhighlychargedionswereshowninFig.1.TheDpeakappearedat1335cm??1onthespectraofgrapheneirradiatedwithhighlychargedions.TheintensityofDpeakincreasedwithfluence.TheratioofintensityofDpeaktothatofGpeakvariedwithfluenceinFig.2.Theratioroselinearlywiththesquarerootoffluencewhenfluencewaslow.Theratiosaturatedwhentheirradiationfluencewashigh.Thecriticalfluencedependedonthechargestateofion.Thehigherchargestateitwas,thelowercriticalfluenceitwouldbe.

  • 标签: CHARGE SPECTRA GRAPHENE
  • 简介:Duetolowactivationcharacteristics,desirablehigh-temperaturestrength,goodresistancetoradiationdamageandusablefabricationproperties,vanadium(V)alloysareattractivecandidatestructuralmaterialsforfusionreactors[1].Irradiationinducedhardening/embrittlementatlowtemperatureisamajorproblemforthematerialsapplicationinfusionreactor[2].Inthisstudy,H/Heionswithvariousenergieswereusedtoirradiateapurevanadium(V)andaValloy(V-4Ti)toobtainadamageplateaufromsamplesurfacetothedepthof1.5m,asshowninFig.1[3].Thedetailsofirradiationparameters(energies,fluences)forHandHeionsareshowninTable1.NanoindentationwasperformedtoinvestigatethehardeningbehaviorofV-4TialloyandpureVunderirradiation.

  • 标签: NANOINDENTATION ALLOY IRRADIATED