简介:SpectroscopicmethodsareusedtoinvestigatecoordinationstructureofN-picolylpolyurethanetransitionmetalcomplexes(PUPYM,M=Co^2+andNi^2+).Geometricalarrangementofligandsinfirst-shellcoordinationsphereofmetalionsispostulatedtobetetrahedralCoL2Cl2andoctahedralNiL2-Cl2Z2.whereListhepicolylgroupandZisahydrate.FromextendedX-rayabsorptionfinestructure(EXAFS)analysis,bondlengthsformetal-chlorineandmetal-ligandofPUPYMaresimilartothoseofsmallmolecularweighttransitionmetalcomplexes.Atwo-phasemodelofPUPYMwhichbestdescribestheexperimentaldataofDMTAandSAXS.isproposed.Onemicrophaseistheharddomainofselfsegregatedhaedsegmentsbroughtaboutbymetal-ligandinteraction.andtheotherphaseisthematrixofsoftsegments.Transitionmetalion-ligandmoietiesandtheirinteractionsdominatethemacroscopicthermalbehaviorofPUPYM.Theligandfieldstabilizationenergydifference(ΔLFSE)betweenmteald-electronsincomplexeswithtwopicolylligandsinthecoordinationsphereofmetalionsandcomplexesmaintainingonepicolylligandascoordinationpendentgroupiscalculatedonthebasisofobservedcoordinationstructure,anditrepresentstheenergysuppliedtosplitcoordinationcross-links.ΔLFSEofpolyurethanenickel(II)complexislargerthanthatofthecobalt(II)complex,Sincethemobilityofhardsegmentsisininverseproportiontothestrengthofcoordinationcross-links.ahigherα-transitiontemperatureofPUPYNi^2+withrespecttoPUPYCo^2+isfoundasexpected.
简介:Surfacemodificationofpolypropylenemicroporousmembrane(PPMM)wasperformedbyatmosphericpressuredielectricbarrierdischargeplasmaimmobilizationofN,Ndimethylaminoethylmethacrylate(DMAEMA).Structuralandmorphologicalchangesonthemembranesurfacewerecharacterizedbyattenuatedtotalreflection-Fouriertransforminfraredspectroscopy(FT-IR/ATR),X-rayphotoelectronspectroscope(XPS)andfieldemissionscanningelectronmicroscopy(FE-SEM).Watercontactanglesofthemembranesurfaceswerealsomeasuredbythesessiledropmethod.Resultsrevealthatboththeplasma-treatingconditionsandtheadsorbedDMAEMAamounthaveremarkableeffectsontheimmobilizationdegreeofDMAEMA.Peroxidedeterminationby1,1-diphenyl-2-picrvlhydrazyl(DPPH)methodverifiestheexsistenceofradicalsinducedbyplasma,whichactivizetheimmobilizationreaction.PurewatercontactangleonthemembranesurfacedecreasedwiththeincreaseofDMAEMAimmobilizationdegree,whichindicatesanenhancedhydrophilicityforthemodifiedmembranes.Theeffectsofimmobilizationdegreesonpurewaterfluxeswerealsomeasured.Itisshownthatpurewaterfluxesfirstincreasedwithimmobilizationdegreeandthendecreased.Finally,permeationofbovineserumalbumin(BSA)andlysozymesolutionweremeasuredtoevaluatetheantifoulingpropertyoftheDMAEMA-modifiedmembranes,fromwhichitisshownthatbothhydrophilicityandelectrostaticrepulsionarebeneficialformembraneantifouling.
简介:Wehavedevelopedalargenumberofexocrineglandsonliquoriceleavesandfacilitatedpolysaccharidesecretion.Liquoricepolysaccharidepossessesstrongerboundwateraffinitytogaseouswatercomparedwithsucroseandglucose.Ourresultsshowthattheboundwateraffinityofliquoricepolysaccharidetogaseouswateris49.75%higherthanglucose(p<0.01).WithN~+implantation(totaldosageof4.68×10~(16)ions/cm~2andenergyof20keV)intodryliquoriceseeds,boththeboundwateraffinitytogaseouswaterandtheboundwatercontentofdryliquoriceleafcanbesignificantlyincreased30.24%(p<0.01)and36.51%(p<0.01)respectivelycomparedwiththesham-irradiatedseeds.Meanwhile,withtheseparameterschosenforN~+implantationintodryliquoriceseeds,theleafpolysaccharidecontentunderwaterstress(ψ_w=-1.5MPa)canincreasesignificantly(p<0.05)andtheplantgrowthcanalsoimprovesignificantly(p<0.05).
简介:Thezonalfieldseffectonthebeta-inducedAlfveneigenmode(BAE)destabilizedbytheenergeticparticlesintoroidalplasmasisstudiedthroughthegyrokineticparticlesimulations.ItisfoundthatthelocalizedzonalfieldswithanegativevaluearoundthemoderationalsurfacearegeneratedbythenonlinearBAE.Intheweaklydrivencase,thezonalfieldswithastronggeodesicacousticmode(GAM)componenthaveweakeffectsonthenonlinearBAEevolution.Inthestronglydrivencase,thezonalfieldsaredominatedbyamoresignificantzerofrequencycomponentandhavestrongereffectsonthenonlinearBAEevolution.
简介:InspiteofthecurrentprevalenceoftheCVD-basedprocesses,theelectricarcremainsaninterestingprocessforthesynthesisofcarbonnanoforms,thankstoitsversatility,robustnessandeasiness.Italsoallowsperformingin-situsubstitutionofcarbonatomsbyhetero-elementsinthegraphenelattice.Ourworkaimstoestablishacorrelationbetweentheplasmaproperties,typeandchemicalcomposition(andthesubstitutionrate)oftheobtainedsingle-wallcarbonnanotubes.TheplasmawascharacterizedbyopticalemissionspectroscopyandtheproductswereanalyzedbyhighresolutiontransmissionelectronmicroscopyandcorelevelElectronEnergy-LossSpectroscopy(EELS).Resultsshowthatahighboroncontentleadstoaplasmatemperaturedecreaseandhinderstheformationofnanotubes.Thiseffectcanbecompensatedbyincreasingthearccurrentand/oryttriumcontent.Theoptimalconditionsforthesynthesisofboron-and/ornitrogen-substitutednanotubescorrespondtoahighaxialplasmatemperatureassociatedtoastrongradialgradient.EELSanalysisconfirmedthattheboronincorporatesintothegraphemelattice.
简介:用磁控溅射方法制备了一系列[C(t)/Cu(2.04nm))In(n=20,30)周期多层膜,利用四端点法、振动样品磁强计研究了多层膜的电磁性质,样品的磁电阻随钴亚层厚度的增大有一最佳值t=1.2nm。利用同步辐射掠入射X射线散射(衍射)技术在不同的X射线能量下研究了耦合多层腹的界面结构,探索了耦合多层膜中磁电阻增强的可能原因。
简介:采用程序升温氮化的方法制备了钼氮化物催化剂,并用EXAFS方法研究了氮化前后Mo原子的局域配位情况。负载MoO3样品的径向结构函数中有三个峰其中前两个峰对应着最近的Mo-O配位壳层,但是第一个峰与第二个峰的比例比晶体MoO3中的比例大很多,表明分子筛负载的MoO3具有更紧密的结构。氮化以后,Mo2N样品的径向结构函数中有三个峰,对应于一个Mo-N和两个Mo-Mo配位壳层,与面心立方模型符合的很好。根据X射线衍射和EXAFS谱的计算表明,Mo2N中的N原子使Mo-Mo键拉长并削弱。分子筛负载的Mo2N样品具有与非负载Mo2N样品相似的径向结构函数,只是对应于Mo-N壳层的峰较弱,表明负载的MoO3更难氮化。
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简介:通过原位浸渍法把FeSO4和其它助剂共同浸渍在两种烟煤上,考察了以FeSO4为主要前驱体的催化剂对这两种煤直接液化的活性与选择性,以及其对液化产物-甲苯可溶物分子量的影响作用,并通过EXAFS和SAXS表征揭示了催化剂在煤上的化学态和粒径分布,结果表明:在一定的反应条件下,FeSO4和两种助剂分别共浸渍在两种煤上时,煤的总转化率及沥青烯和轻质产物的产率均比不添加催化剂时的结果提高1倍左右,与铁的硫化物相比,以FeSO4为主要前驱体的催化剂沥青烯和轻质产物具有较高的选择性,生成的重质甲苯可溶物具有较大的分子量;EXAFS和SAXS表明,原位浸渍在煤上的FeSO4表现为纳米相,助剂Na2S和尿素的添加主要改变了Fe原子周围的配位原子种类以及它们的成键方式,而对其颗粒分布影响较小,催化剂在汾西煤上的分布较其在兖州煤上的差一些。
简介:本文测定了在高压条件下两种金属(钙和锌)的8-羟基喹啉络合物的晶体粉末样品的发光行为和原位x-光衍射光说。结果表明,压力对其发光性质产生极大的影响。随着压力的增加,8-羟基喹啉钙的发光强度在3GPa以内时大大增加。随后发光强度快速下降,到7GPa左右时几乎为零。而8-羟基喹啉锌的发光随压力的增加而逐渐降低,到7GPa左右时常压的10%。高压下的原位x-光衍射结果表明8-羟基喹啉钙的晶体在3-4GPa开始发生非晶化相变,在7GPa时该非晶化相变完成,样品的x-光衍射完全消失。而8-羟基喹啉锌在压力的作用下(至16GPa)没有发生明显的相变。