简介:Thetransportprocessof12CionsinwaterwasstudiedwithSRIMcodeandGeant4toolkit.TheSRIMresultsindicatethatthetransversediffusionof12Cionbeamcausesdistortionofenergydepositalongthebeamdirection.Thedistortionbecomesmorenotableasthetrans-versediffusionincreases.ThesimulationresultsofGeant4indicatethattheinfluenceofsecondaryfragmentsonenergydepositdistributionwouldbethemainfactorcausingthedistortioninhigherenergyrange.Intheregionadjacenttothebeamlinewherethecontributionfrom12Cionsdomi-nates,thecontributionsfromsecondaryfragmentsareignorable.Thefurtherfromthebeamaxistheregionlocates,thelargerthecontributionsfromsecondaryfragments,untilthecontributionsfromsecondaryfragmentsareignorable.Thefurtherfromthebeamaxistheregionlocates,thelargerthecontributionsfromsecondaryfragments,untilthecontributionsfromsecondaryfrag-mentsexceedthatof12C.Amongallthesecondaryfragments,thecontributionsofH,HeandBionsaremostlynotable.Itisalsofoundthatsomepositron-emittingsecondaryfragmentscouldbeveryusefulforpositionemittingtomography(PET).
简介:利用角分辨紫外光电子谱对乙烯和乙炔气体在Ru(1010)表面的吸附及与K的共吸附的研究结果表明:当衬底温度超过200K,乙烯即发生脱氢反应,σCH和σCC能级均向高结合能方向移动。在室温下,σCH和σCC能级位置与乙炔在Ru(1010)表面的吸附时的分子能级完全一致。乙烯发生脱氢反应后的主要产物为乙炔。衬底温度从120K到室温,Ru(1010)表面上乙炔的σCH和σCC能级均未发现变化。室温下乙炔仍然可以在Ru(1010)表面以分子状态稳定吸附。在有K的Ru(1010)表面上,室温时σCC谱峰几乎。碱金属K的存在促进了乙炔的分解。
简介:BasedonthesinglebiasingelectrodeexperimentstooptimizetheconfinementofplasmainthedeviceofKT-5Ctokamak,dual-biasingelectrodeswereinsertedintotheKT5Cplasmaforthefirsttimetoexploretheenhancingeffectsofbiasingandthemechanismsofthebiasing.Bymeansofapplyingdifferentcombinationsofbiasingvoltagesontothedualelectrodes,thechangesofE_r,whicharethekeyfactorforboostinguptheE_r×Bflowshear,wereobserved.Thetimeevolutionshowedthattheinnerelectrodeplayedamajorroleindual-biasing,whichdrewlargercurrentthantheouterone.Theouterelectrodeproducedlittleinfluence.Itturnedoutthatthedual-biasingelectrodeswereaseffectiveasasingleoneinimprovingtheplasmaconfinement,forthemechanismofbiasingwasessentiallyanedgeeffect.
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:用同步辐射X荧光微束扫描技术测量了未经处理的,腹腔注射CdCl2的及注射后用新型的络合剂促排的三组Wistar大鼠的肾切片。结果表明Cd主要分布在肾的皮质部分,而髓质部分含量很低。用多元素统计分析探讨了元素间的关系;在正常鼠肾中,元素分布基本上聚类成两大类。其中微量元素Cu,Zn,Mn和Se为一类,它们在肾中的分布有较强的共位性,处于平均状态;急性中毒时,Cd与Se的距离最近。有较强的相互作用。其次是与Ca,此时元素的分类不明显,平衡被打乱;中毒后用新药促排的Se和Zn强相关并聚为一类,其它元素间的相关性变弱,元素基本上又趋于分为两类。
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