简介:Theγ-Fe2O3nanoparticlescoatedwithDBSandCTABwerepreparedbythemicroemulsionmethod.Thecoatedsamplesshowenhancednonlinearopticalpropertiescomparedwiththeirbulkcouterpart.The.Moessbauerspectraatroomtemperatureweremeasuredforthecoatedferricoxides.Themonolayersoftheorganicmoleculearefoundtohaveastrongchemicalbondwiththesurfaceatomsandthushaveasignificantinfluenceontheelectronstructureofparticlesurface.@1999ActaMetallurgicaInc.
简介:TheNi-AlalloycontainingCr,FeadditiveswerepreparedasRaneyNiCatalystbyhighenergymilling.ThesizeandsurfacestateofNi-Alalloypowderwerestudiedbyparticlesizeanalyzerandsanningelectronmicroscopy.theStructurewasanalyzedbyXRDandMoessbauermethods.Theresultsshowedthatafterahigh-energymilling(HEM).theNi-Alalloytransformstoanano-scaleNiAlstructurewithrichAl.Byannealingthealloy,ametastableNi2Al3phasecanbeobtained.
简介:ThetransientopticalpropertiesofnovelPbSnanoparticlescoatedwith2.6-O-diallyl-β-cyclodextrines(CDs)werestudiedbythefemtosecondpump-probetechnique.Theresultsshowthattheultrafasttransient-inducedabsorptionforthenovelcase.ComparedtothePbSnanoparticlesstabilizedwithpolyvinylalcohol(PVA),wefindthattheprocessforthenovelcaseisdifferentfromthePbS(PVA),WesuggestthattheCDssurfacemodificationcantrapholesonthesurfaceofPbSnanoparticles.ThiscaninduceanefficientchargeseparationbetweenthePbSnanoparticlesanditssurfaceandresultinanultrsafast-inducedabsorptionfornovelPbSnanoparticles.
简介:Thenanoparticlesγ-Fe2O3coatedwithsurfactants.DBS,STandCTAB.repsectively.weresynthesizedbymicroemulsionmethod.Thecoatedferricoxides.whichshowenhancednonlinearopticalpropertiescomparedwiththeirbulkcounterpart.wereprobedbyEXAFSinsolutionforms.Thex=-rayabsorptionspectraforFeKedgeweremeasuredatroomtemperaturebyhelpofsynchrotronradiationlightsource.Extendedx-rayabsorptionfinestructureanalysisshowsthatthecoatinglayersoforganicmoleculesinteractwithsurfaceatomsofnanopartices,theFe-Obondlengthwasextended.
简介:Themicrostructuresofloadedorganicphasesofthreequaternaryaminesolventextractionsystemsforgold,whichwereN263-xylene,N263-tributylphosphate(TBP)-dodecaneandN263-2-ethylhexanol(isooctanol)-dodecane(N263-trialkylmethylammoniumchloride;alkyl=C8-C10),werestudiedbyFouriertransforminfrared(FTIR)spectroscopyandextendedX-rayabso\rptionfinestructure(EXAFS)spectroscopy.AccordingtotheEXAFSresults,itwasfoundthatthegoldcoordinationenvironmentwasthesamebeforeandafterextraction.However,theC≡NstretchingvibrationsofAu(CN)2-werealsofoundtobedifferent,InordertoexplainthedifferencesintheIRcharacteristicsofC≡Ninthethreeextractionsystems,threemicrostructuremodelsareproposed.FortheN263-xylenesystem,themodelisasimpleionpair.Fortheothertwosystemswithamodifier(TBPandisooctanol),themodelsaretwosupramolecularstructuesbasedonhydrogenbondingbetweenthemodifierandAu(CN)2^-.SomerelatedworksuchasonthehydrationofacetonitrileandthefinestructureofC≡NinsolidKAu(CN)2wasalsoperformedinordertoofferadditionalsupportingevidenceforthereliabilityoftheproposedmodels.
简介:AseriesofoxideizedCO-K-Mo/γ-Al2O3catalystsamples,preparedbyimpregnatingoxidizedK-Mo/γ-Al2O3sampleswithanaqueoussolutionofcalculatedCo(NO3)2andthencalcininginairattemperaturesof350℃,500℃65℃and800℃respectively,weresulfidedandtheninvestigatedfortheactivityinthesynthesisofmixedalcoholsfromCOhydrogenationunderconditionsofp=5.0MPa,T=350℃andGHSV=4800h^-1.TheresultsdemonstratethattheadditionofcobaltpromoterisfavorabletotheformationofhigheralcoholsandtheopimumcalcinationtemperaturesafterimpregnatingwithCo^2+areabout500-650℃.ThestructureofCoandMospeciesontheoxidizedandsulfidedsampleswasdeterminedbyX-raydiffraction(XRD),laserRamanspectrum(LRS)andextendedX-rayabsorptionfinestructure(EXAFS).Foroxidizedsamplecalcinedat350℃,cobaltexistsasCo3O4spectiesandcoversthesurfaceofK-Mo-Ospecies,thestructureofK-Mo-OspeciesisthesameasthatinK-Mo/Al2O3sample.TheinteractionbetweencobaltandK-Mo-Ospeciesisrelativelyweak.Aftersulfidation.Cobaltexistsassulfidecrystalliteswithanoctahedralcoordinatedstructure,andmolybdenumasMoS2crystallites.Foroxidizedsamplescalcinedat500-650℃,CocomponentinteractswiththeK-Mo-Ospeciesanddestroysthelong-rangeorderoftheK-Mo-Ospectesgradually,Aftersulfidation.CotendstoexistasasulfidewithtetrahedralcoordinatedstructureandMostillasMoS2crystallites.Foroxidizedsamplecalcinedat800℃,CocomponentexistsmainlyasCoAl2O4species,mostofwhichcannotbesultidedduringsulfidation.
简介:ToobtainthermotolerantmutantsofG.oxydans,whichcanenhancethetransformationrateofL-sorboseto2-Keto-L-gulonate(2-KLG)at33℃inatwo-stepprocessofvitaminCmanufacture,ionbeamwasusedasamutationsource.GluconobacteroxydansGOandBacillusmegateriumB0wereusedinthisstudy.TheoriginalstrainGluconobacteroxydansGOwasmutatedbytheheavyionimplantationfacilityattheInstituteofPlasmaPhysics,ChineseAcademyofSciences.SeveralmutantsincludingGluconobacteroxydansGI13wereisolatedandcoculturedwithBacillusmegateriumB0at33℃inshakingflasks.TheaveragetransformationrateofthenewmixedstrainGI13-B0inpergram-moleculereached94.4%aftersevenpassagesinshakingflasks,whichwasincreasedby7%whencomparedwiththeoriginalmixedstrainG0-B0(GluconobacteroxydansG0andBacillusmegateriumB0).Moreover,thetransformationrateofI13B0wasstableat94%attemperaturesrangingfrom25℃to33℃,whichwouldbeofmuchvalueinreducingenergyconsumptioninthemanufactureofL-ascorbicacid,especiallyintheseasonofsummer.Toclarifysomemechanismofthemutation,thespecificactivitiesofL-sorbosedehydrogenaseinbothG0andGI13wereestimated.
简介:InthedischargeofEASTtokamak,itisobservedthat(2,1)neoclassicaltearingmode(NTM)istriggeredbymodecouplingwitha(1,1)internalmode.Usingsingularvaluedecomposition(SVD)methodforsoftX-rayemissionandforelectroncyclotronemission(ECE),thecouplingspatialstructuresandcouplingprocessbetweenthesetwomodesareanalyzedindetail.TheresultsofSVDforECErevealthatthephasedifferencebetweenthesetwomodesequalstozero.Thisisconsistentwiththeperfectcouplingcondition.Finally,performingstatisticalanalysisofγ1/1,ζ1/1andω2/1,wefindthatγ1/1moreaccuratelyrepresentsthecouplingstrengththanζ1/1,andγ1/1isalsostronglyrelatedtothe(2,1)NTMtriggering,whereγ1/1isthewidthof(1,1)internalmode,ζ1/1istheperturbedamplitudeof(1,1)internalmode,andω2/1denotesthemagneticislandwidthof(2,1)NTM.