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简介:TheCe-Fe-OmixedoxidewitharatioofCe/Fe=7:3,whichwaspreparedbycoprecipitationmethodandemployedasoxygencarrier,fordirectpartialoxidationofmethanetosyngasintheabsenceofgaseousoxygenwasexplored.ThemixedoxidewascharacterizedbyX-raydiffraction(XRD),X-rayphotoelectronspectroscopy(XPS)andscanningelectronmicroscopy(SEM),andthecatalyticperformanceswerestudiedinafixed-bedquartzreactorandathermogravimetricreactor,respectively.Approximately99.4%H2se...
简介:LanthanidedopedNaYF4microcrystalsweresynthesizedviaafacilehydrothermalmethod.MulticolorupconversionluminescencewasobservedinNaYF4microcrystalsdopedwithYb3+/Er3+,Yb3+/Tm3+,andYb3+/Er3+/Tm3+undertheexcitationof980nminfraredlight.Importantly,theexcitationpowerdensitydependenceofupconversionemissionintensityindicatedclearlytheenergytransferfromTm3+toEr3+ionsundertheexcitationoflowpowerdensity(5×102–9×102W/cm2).Meanwhile,theinverseenergytransferfromEr3+toTm3+ionsundertheexcitationofrelativelyhigherpowerdensity(4.1×104–4.9×104W/cm2)wasalsorevealed.ThiswasadirectevidenceforreversibleenergytransferbetweenEr3+andTm3+ions.Undertheexcitationofhighpowerdensity(4.1×104–4.9×104W/cm2),darksensitizerswerealsomotivatedsothatthebottleneckeffectofhighconcentrationYb3+iondopingwasbroken.ThiswasthemainreasonforrealizinghighupconversionefficiencyofthesampleswithheavydopingofYb3+ion.
简介:Inthedirectfiredfurnaceofacontinuousannealingline,sealrollsaresusceptibletodeformationthatleadstosurfacedefectsofsteelstrips.Accordingtofailureanalysis,thereasonsincludeimproperstructuraldesignandheatimbalance.Animproveddesignhasbeenproposedtoreducestressconcentrationandthermalradiation.Aheattransfermodelhasbeenemployedtodeterminetheproperwaterflowrateforrollcooling.Industrialapplicationprovesthatsealrollswiththenewdesignhaslessdeformationandlongerservicelife.