简介:DiamondfromLiaoning,Chinawasstudiedbysynchrotronradiationandinfraredspectrum.Thedistributionofdislocationsinthespecimenthasbeenrevealed.Anewmethodtodeterminetheorientationofcrystaldefectshasbeenproposedandtheorientationindexesofthedislocationsinthespecimenwerecalculatedbythismethod.Ithasbeenfoundthatthedislocationsinthespecimentarenearbutnotpreciselyparallelto{111}planes,Themaximumanglebetweendislocationand{111}planeisabout16°.AlmostallthedislocationsinthespecimenthavethesameBurgersvector1/2[101]andimplythesamenessoftheirorigination.
简介:烷基配糖物1并且芳基glycosides24stereospecifically高度从商业地可得到的开始的材料在46步上被综合。acetobromo的联合反应--有unprotectivedihydroxyaglycon的D葡萄糖面对钠氢氧化物面对银氧化物,或与芳香的aglycon生产了关键中介。仅仅配置glycosides在这个过程被形成。所有这些glycosides的合成第一次被报导。
简介:Naturalsurfacecoatingscollectedfromnaturalsubstances(NSCsNS)wereemployedtostudytherolesofthemainchemicalcomponents(ironoxides,manganeseoxides,andothercomponents)incontrollingtheadsorptionoflead(Pb)andcadmium(Cd)inaquaticenvironments.TheselectivechemicalextractionfollowedbytheadsorptionofPbandCdexperimentsandstatisticalanalysis,wereusedtoinvestigatetheadsorptionpropertyofeachcomponent.Hydroxylaminehydrochloridewasusedtoremovemanganeseoxidesselectively,andsodiumdithionitewasusedtoextractironoxidesandmanganeseoxides.TheresultindicatedthatironoxidesandmanganeseoxidesplayedanimportantroleintheadsorptionofPbandCdonNSCsNS,andtherelativecontributionwasabouttwo-thirds.Thecontributionofmanganeseoxideswasthegreatest,withalesserroleindicatedforothercomponents.TheadsorptionabilityofmanganeseoxidesforPbandCdwasgreaterthanthatofironoxidesorothercomponentsforPbandCd.ThePbadsorptionobservedineachcomponentwasgreaterthanCdadsorption.
简介:Directconversionofmethanetohigherhydrocarbonsisaneffectiveprocesstosolvetheproblemofnaturalgasutilization.Althoughremarkableprogresshasbeenachievedonthedehydro-aromatizationofmethane(DAM),lowconversioncausedbyseverethermodynamiclimitations,cokeformation,andcatalysisdeactivationremainimportantdrawbackstothedirectconversionprocess.MolybdenumcatalystssupportedonHZSM-5typezeolitesupportareamongthemostpromisingcatalysts.Thisreviewfocusesontheaspectsofdirectmethaneconversion,intermsofcatalystscontainingmetalandsupport,reactionconditions,andconversionindifferenttypesofreactors.Thereactionmechanismforthiscatalyticprocessisalsodiscussed.
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简介:Awidevarietyofdifferenttypesofmicroorganismsareknowntoproduceintracellularenergyandcarbonstorageproducts,whichhavebeengenerallydescribedasbeingpoly(β-hydroxybutyrate),PHB,butwhichare,moreoftenthannot,copolymerscontainingdifferentalkylgroupsattheβ-position.Hence,PHBbelongstothefamilyofpoly(β-hydroxyalkanoastes),PHA,allofwhichareusuallyformedasintracellularinclusionsinbacteriaunderunbalancedgrowthconditions.Recently,itbecameofindustrialinteresttoevaluatethesePHApolyestersasnaturalbiodegradableandbiocompatibleplasticsforawiderangeofpossibleapplications,suchassurgicalsuturesorpackagingcontainers.Forindustrialapplications,thecontrolledincorporationofrepeatingunitswithdifferentchainlengthsintoaseriesofcopolymersisdesirableinordertoproducepolyesterswitharangeofmaterialpropertiesbecausephysicalandchemicalcharacteristicsdependstronglyonthepolymercomposition.Such"tailor-made"copolymerscanbeproducedundercontrolledgrowthconditionsinthat,ifadefinedmixtureofsubstratesforacertaintypeofmicroorganismsissupplied,awelldefinedandreproduciblecopolymerisformed.
简介:AmmoniumcanchangethetypeofnaturalclinoptilolitefromJinyunofZhejiangProvinceofChina.Thecharacterofexchangeandselectivityofammoniumtypeclinoptilolitetothealkaliandalkaline-earthmetalwereinvestigated,theheatresistanceandnitricacid-resistanceofnaturalclinoptilolitewerediscussed.AlltypesofclinoptilolitewereresearchedbymeansofX-ray,IRspectroscopy,DTAanalyses.Theionexchangewasexperimentedbycolumnoperation,indicatingthatthevalidamountofexchangecapacityofNH4^+typeclinoptilotiesismorethan25mg/g.
简介:Thethermalperformanceofarectangularloopwithahorizontalheatingsegmentandapartlycoolingverticallegisstudied.Byone-dimensionalapproach,traditionalfrictionfactorandempiricalcorrelation,amodifiedGrashofnumberGr^*whichturnsouttobeveryimportantinthedescriptionofcirculationflowisintroduced.AnewcorrelationforNusseltnumberofthehorizontalheaterisobtainedandthecomparisonwithexperimentalvaluesshowsgoodagreement.
简介:Naturalfreshwatersurfacecoatings(biofilmsandassociatedminerals),whichweredevelopedintheNanhuLake,Changchun,P.R.China,wereusedasanefficientbiosorbentfortheremovalofCd(Ⅱ)fromaqueoussolutions.ThebatchexperimentswerecarriedouttodeterminetheadsorptionpropertiesofCd(Ⅱ)ontothenaturalsurfacecoatings.TheclassicalLangmuiradsorptionisothermwasappliedtoestimatingtheequilibriumcoefficientsofCd(Ⅱ)adsorbedonthesurfacecoatings.Theresultsshowthatthemaximumadsorptioncapacityofthesurfacecoatingsis434.78μmolCd/m2(beingequalto0.17mmolCd/gofsurfacecoatingsor10.38mmolCd/gFe)andtheCd(Ⅱ)removalfromsolutionmediabythenaturalsurfacecoatingswasshowntobestronglyaffectedbysolutionpHandionstrength.TheresultedinformationalsoindicatesthatthemaximumCdremovalefficiency(CRE)wasdeterminedtobeapproximately90%atinitialCdmassconcentrationof0.1mg/L(theconcentrationlimitofCd(Ⅱ)inwastewatersfordischargeinaquaticmediainChineselegislation),andthekineticadsorptionofCd(Ⅱ)ontothesurfacecoatingsisfastwitharound70%ofthetotaladsorption-takingplacein150mininsolutionunderthecontrolledlaboratoryconditions(mineralsaltssolutionwithdefinedspeciation,ionicstrength0.05mol/L,and25℃).WiththeadvantageofhighCdadsorptioncapacity,thenaturalsurfacecoatingsappeartobeapotentiallyeffectivebiosorbentfortheremovalandrecoveryofCd(Ⅱ)frompollutedwater.
简介:ThenaturalconvectiveheattransferperformanceofanaluminumhexagonalhoneycombactingasanovelheatsinkforLEDcoolingisexperimentallyinvestigated.Theconceptofaddinganadiabaticsquarechimneyextensionforheattransferenhancementisproposed,andtheeffectsofchimneyshape,height,anddiameterarequantified.TheaverageNuavofaheatedhoneycombwithstraightchimneyissignificantlyhigherthanthatwithoutchimney,andtheenhancementincreaseswithincreasingchimneyheight.Atagivenchimneyheight,honeycombswithdivergentchimneysperformbetterthanthosewithconvergentones.Forafixeddivergentangle,theNuavnumberincreasesmonotonicallywithincreasingchimneyheight.Incontrast,withtheconvergentanglefixed,thereexistsanoptimalchimneyheighttoachievemaximumheattransfer.
简介:AccordingtotheThomsonReuterreporton20June2013,the2012ImpactFactorofJournalofNaturalGasChemistry,renamedasJournalofEnergyChemistryin2013,is1.405,whichranksfirstamongchemistryjournalsinChina.WewouldliketoexpressourappreciationtoalltheauthorswhohavecontributedtheirgoodworktotheJournal.Thefollowingisthelistofthearticlespublishedin2010and2011whichreceivedthemostcitationsandthuscontributedthemosttothenewimpactfactor.
简介:Naturalconvectionheattransferinahorizontalenclosurefilledwithanisotropicporousmedia,beingisothermallyheatedatbettomandcooledattopwhiletheverticalwallsbeingadiabatic,isnumericallystudiedbyapplyingtheBrinkmanmodel-amodifiedformofDarcymodelgivingconsideratiointotheviscouseffect.Theresultsshowthat:(1)alargerpermeabilityratio(K^*)causesalowerflowintensityintheenclosureandasmallerNusseltnumber,allNusseltnumbersapproachunityinthelimitofK^*→∞;alargerthermalconductivityratio(λ^*)causesastrangerdistortionofisothermsintheenclosureandahigherflowvelocitynearthewalls,alltheNusseltnumbersapproachunityinthelimitofλ^*-→0,thepermeabilityandthermalconductivityratiosgenerallyhaveopposingeffectsontheNusseltnumber.(2)anincreasingDarcynumberdecreasestheflowintensityandheattansferrates,whichismoresignificantatalowerpermeabilityratio.Inparticular,withK^*≤0.25,theNusseltnumberforDa=10^-3woulddifferfromthatofDarcyflowuptoanamountof30%,ananalysisneglectingthenon-Daricaneffectwillinevitablybeofconsiderableerror.