学科分类
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40 个结果
  • 简介:AdsorptionpropertiesofL-histidineonactivecarbonwerestudiedinthepaper,whichareaffectedbythemainparameters,suchasthequantitypercentofactivecarbon,pHvalueofthesolution,thetimeofadsorptionequilibriumandadsorptiontemperature.TheresultsindicatethatadsorptionequilibriumtimeofL-hisonactivecarbonisabout80minutes.Withtheincreasingofthequantitypercentofactivecarbon,theadsorbanceofL-hisdecreasessharply,andincreaseslighterafterthat.Whenthequantitypercentofactivecarbonis10%,theadsorbancereachestheminimum.pHvalueofsolutionandextractiontemperaturehavegreataffectionontheadsorption.WhenthepHvalueishigherorlowerthanthepIofL-his,theadsorbanceissmall,evenzero.Itisproventhattheexperimentalequilibriumdatawhichareobtainedundertheconditionsof80℃andpH=1.0,arefittedwiththeFreundlichequation:q=2.5914c0.8097.TheresultscanprovidecertainreferencesinL-hisadsorptionprocessofindustrialoperation.

  • 标签: 吸附特征 L-组氨酸 活性碳 吸附平衡 氨基酸
  • 简介:Thestructureofpolyimidefrom1,4-bis(3’,4’-dicarboxyphenoxy)benzeneand4,4’-oxydianilinefilmspecimensbeforeandafterhotstretchinghasbeeninvestigatedbyWAXD,DSCandFTIR.AsevidencedbyboththeWAXDandDSCresults,itcouldbebelievedthatstraininducedcrystallizationdidtakeplaceafterhotstretching.Meanwhile,shiftingpositionandsplittingofsomebandpeaksexistedontheFTIRspectrogramswereexplainedintermsoftheclosepackingofchainsandthechangesofinter-molecularcharge-transferinteractionbetweenimidegroupsandaromaticgroupsuponcrystallization.

  • 标签: POLYIMIDE ORIENTATION CRYSTALLIZATION FTIR
  • 简介:AhighMwofPLLAwassynthesized,itintendedtobeusedinthemanufactureofbioabsorbablescrewappliedinbonefractureinternalfixation.Theopticalreactionconditionshavebeendiscussed.

  • 标签: 合成 聚左旋乳酸 骨折固定
  • 简介:在这研究,(L减水乳酸)(PLLA)一系列monodispersed被戒指洞聚合poly综合与Schiff基础铝催化剂,并且数字一般水准的效果分子的重量(M结晶化和PLLA的融化的行为上的n)被微分扫描热量测定(DSC)和宽角度的X光检查衍射(WAXD)调查。PLLA的全部的结晶化率是M与M-dependent,>18.6kg/mol的n。另外,当PLLA的Mn是18.6kg/mol时,融化的热含量(Hm)显示出最大的价值(87.1J/g),它是最高报导的价值到现在为止。为水晶形成从的变化的批评温度-到形式,在等温的结晶化增加的晶体与M处理n增加。在再热的过程,high-MnPLLA在主导的融化山峰以前表明了一座小exothermal山峰,相应于水晶转变从-到-form,但是low-MnPLLAdidnt表演水晶转变的山峰。这些不同结晶化和融化的行为与不同Mn。

  • 标签: 下线 服务 迁移
  • 简介:(L减水乳酸)(PLLA)Poly,/pristine蛭石nanocomposites被准备由融化掺双轴的extruder,和热、机械的性质的蛭石分散状态的详细信息和蛭石的效果系统地被学习。当装载内容不超过3wt%时,结果证明在矩阵的蛭石的分散相当好。太古的蛭石能显然在nonisothermal结晶化期间改进融化结晶化温度。两结晶化时间跨度和PLLA的spherulitic尺寸由提高PLLA的主要成核在等温的结晶化状况下面与蛭石的增加的数量减少。并且增加的蛭石能也改进张力的模量和PLLA的Izod影响力量。为PLLA上的蛭石的起核心作用的效果的内在的机制被建议是在蛭石和PLLA之间的取向附生的结晶化和特定的相互作用。

  • 标签: 下线 服务 迁移
  • 简介:Antibacterialpoly(D,L-lactide)(PDLLA)fibrousmembranesweredevelopedviaelectrospinning,followedbysurfacemodificationwhichinvolvedplasmapretreatment,UV-inducedgraftcopolymerizationof4-vinylpyridine(4VP)andquaternizationofthegraftedpyridinegroupswithhexylbromide.ThesuccessofmodificationwithquatemizedpyridiniumgroupsonthePDLLAfibrousmembraneswasascertainedbyX-rayphotoelectronspectroscopy(XPS).TheantibacterialactivitiesofthesemembraneswereassessedagainstGram-positiveStaphylococcusaureus(S.aureus)andGram-negativeEscherichiacoli(E.coli).ThePDLLAfibrousmembranesmodifiedwithquaternizedpyridiniumgroupsshowedantibacterialefficiencyagainstbothbacteriaashighas99.999%.Theresultsdemonstratedthattheantibacterialactivitywasbasedontheinteractionofthepositivechargeofpyridiniumgroupandnegativelychargedcellmembraneofbacteria,resultinginlossofmembranepermeabilityandcellleakage.

  • 标签: 等离子体表面改性 聚乳酸纤维 吡啶季铵盐 抗菌活性 纤维膜 金黄色葡萄球菌
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  • 简介:稀土元素aryloxides由各种各样的烷基组代替了[行(浆)3]例如甲基,isopropyl和tertbutyl,被用作单个部件催化剂影响L减水乳酸(LLA)的戒指洞聚合。催化活动,聚合特征,聚合动力学和机制被学习。稀土元素aryloxides的催化活动被结构和烷基组的数字在苯基戒指上影响,这被发现。越强壮烷基组的电子捐赠能力,催化活动将是越多higher。代用品组的数字的增加将导致一项更高催化的活动。镧tris(2,4,6-tri-tert-butylphenolate)[La(OTTBP)3]在所有镧aryloxides之中展出最高的活动。根据1H-NMR数据,LLA聚合经由包含减水乳酸的酰氧债券的劈开的协作插入机制继续了,这被建议。关键词戒指洞聚合-L减水乳酸-稀土元素aryloxides这个工作被山西省(号码2006011069)的自然科学基础和山西省(号码2009011059-7)的关键实验室的开的基础支持。

  • 标签: 聚合反应动力学 环烷基 稀土 开环 催化活性 乳酸
  • 简介:Arareearthcoordinationsystemwasfirstinvestigatedasanewtypeofcatalystforthering-openingpolymerizationofα-aminoacidN-carboxyanhydrides(NCAs).Theresultsforthepolymerizationofγ-stearyl-α,L-glutamate(SLG)NCAusingneodymiumacetylacetonate(Nd(acac)3)-orneodymiumtris(2-ethylhexylphosphonate)(Nd(P204)3)-triethylaluminum-waterascatalystswerecomparedwiththoseusingconventionalcatalysts.Itwasfoundthatthehelicalpoly(γ-stearyl-L-glutamate)withhighmolecularweightaswellasnarrowmolecularweightdistributioncanbeobtainedinthepresenceofNd(acac)3/AlEt3-1/2H2O.ThepolymerobtainedwascharacterizedbyIRandNMRspectroscopy.

  • 标签: Rare earth COORDINATION catalyst RING-OPENING POLYMERIZATION
  • 简介:Thestructureandkineticsofthecomplexformedbyhyaluronicacid(HA)andpoly(L-lysine)(PLL)werestudiedbytimeresolvedlaserlightscattering,TEM,andAFM.BecauseHAhasahydrophilicbackbone,thecomplexesformedbyHAandPLLaredifferentfromthoseformedbyoppositelychargedpolyelectrolytesbothhavinghydrophobicbackbones.Insteadofformingstrongaggregatesandevenprecipitates,thecomplexinthepresenceofexcessHAisstableinthestudiedtimeperiod.Moreimportantly,thecomplexspontaneouslyformscore-coronastructurebytherearrangementofHAchains.ThecoreiscomposedofcomplexrichofPLLandthecoronaismainlyHA.FurtheranalysisshowsthatthehydrogenbondformedbyHAcreatesabarrierhinderingthefurtherrelaxationofHAchains.Theautomaticformationofcore-coronastructurebyPLL/HAishelpfulnotonlytounderstandtherelaxationofpolyelectrolyteincomplex,butalsotodevelopdrugcarrierswithdesirableproperties.

  • 标签: POLYELECTROLYTE complex Core-corona STRUCTURE Hyaluronic acid
  • 简介:ThepreparationandcharacterizationofanimmobilizedL-glutamicdecarboxylase(GDC)werestudiedThisworkistodevelopasensitivemethodforthedeterminationofL-glutamateusinganewbiosensor,whichconsistsofanenzymecolumnreactorofGDCimmobilizedonanovelionexchangeresin(carboxymethyl-copolymerofallyldextranandN.N'-methylene-bisacrylamideCM-CADB)andionanalyzercoupledwithaCO2electrode.Theconditionsfortheenzymeimmobilizationwereoptimizedbytheparameters:buffercompositionandconcentration,adsorptionequilibrationtime,amountofenzyme,temperature,ionicstrengthandpH.ThepropertiesoftheimmobilizedenzymeonCM-CADBwerestudiedbyinvestigatingtheinitialrateoftheenzymereaction,theefffectofvariousparametersontheimmobilizedGDCactivityanditsstability.AnimmobilizedGDCenzymecolumnreactormatchedwithaflowinjectionsystem-ionanalyzercoupledwithCO2electrode-datacollectionsystemmadeuptheoriginalformoftheapparatusofbiosensorfordeterminingofL-glutamateacid.Thelimitofdetectionis1.O×1O-5M.Thelinearityresponseisintherangeof5×1O-2-5×1O-5M.Theequationoflinearregressionofthecalibrationcurveisy=43.3x+181.6(yisthemilli-voltofelectricalpotentialresponse,xisthelogarithmoftheconcentrationofthesubstrateofL-glutamateacid).Thecorrelationcoefficientequals0.99.Thecoefficientofvariationequals2.7%.

  • 标签: 离子交换树脂 L-谷氨酸 酶反应器
  • 简介:ThepreparationofconductingPPQfilmwasfirstreportedinthepreviouspaper.Itisveryinterestingthatthisfilmishighlysensitivetomoistureinair.ThehydrationanddehydrationofthefilmareaccompaniedbychangenotonlyincolorbutalsoinconductivityandUV-visiblespectrum.TheconductingPPQisreducedtoPPQandlosesitsconductivityafterbeingsoakedinwater.

  • 标签: POLYPHENYLQUINOXALINE ClO4- COMPLEX Electrical CONDUCTIVITY WATER
  • 简介:Theadsorptionbehaviorofionicgoldontochelatingfibercontainingamidoximegroupswasinvestigated.ThechelatingfiberpresentshighadsorptioncapacityforionicgoldAu^3+(upto626mg/g,whenthecontentofamidoximegroupreaches7.59mmol/g),andpossessestheabilitytoreducetheAu^3+intometallicgold,Intheredoxprocess,theamidoximegroupisoxidizedintocarboxylgroup.

  • 标签: 螯合纤维 三价金离子吸附行为 偕胺肟基团
  • 简介:Poly(β-carboxyethylmethylsiloxane)-LiClO4andpoly(β-alkoxylethylmethylsiloxane)-LiClO4crosslinkedfllmshavebeenprepared.Theionicconductivityofthefilmsdependsonthepolymerspecies,concentrationoflithiumperchlorate,temperatureandcontentofcrosslinkingagent.Theeffectofhighpolarorganicsolvent1,4-butyrolactoneontheionicconductivityandmechanicalpropertiesofpoly(β-carhoxyethylmethylsiloxane)-LiClO4systemwasalsoinvestignied.

  • 标签: IONIC conductivity: Poly(β-alkoxycarbonylethylmethylsiloxane)- LITHIUM Complex 1
  • 简介:Ionicconductivityvaluesforsegmentedpolyetherpolyurethaneurea(PEUU)complexeswithLiClO4weredeterminedandvaluesashighas~1.1×10-4S·cm-1at353Kand~1.0×10-5S·cm-1at306Kwereachieved.TheionicconductivitydatawereanalyzedusingtheVTF(Vogel-Tamman-Fulcher)equationandWLF(Williams-Landel-Ferry)typeequation.Valueshavebeenestimatedforthe"apparent"activationenergiesofiontransportfromVTFequationandtheylieintherange2.70—5.53kJ·mol-1.

  • 标签: Segemented POLYETHER polyurethaneureas Complex: Solid IONIC
  • 简介:TheL-proline-functionalizedpolystyrenewith1-methyldecylenespacerwassynthesizedfrom2%divinylbenzene-crosslinkedpolystyrenegelvia10-bromo-1-methyldecylpolystyreneintermediate.Aftercomplexedwithcopper(Ⅱ)ion,thepolymerwithL-prolineligandwasusedasthechiralstationaryphase(CSP)forligandexchangechromatographyofaminoacidracemates.TheresultsshowedthattheCSPpossessedpowerfulenantioselectivityandallracematesofthefifteentriedaminoacidswerecompletelyseparated.

  • 标签: 左旋-脯氨酸-职能化聚苯乙烯 手性固定相 1-甲基癸烯 色谱分离 氨基酸消旋体