简介:TheadsorptionkineticsofPb^2+ondifferentsoilsandmineralswithvariablechargeswasstudiedbythetwoion-selectiveelectrodetechniqueatdifferentpHandconcentrations.Theresultsshowedthatmorethan95%ofadsorptiononallthesamplesoccurredduringthefirst5minutes.Alladsorptiontime-dependentdatacouldfitthesurfacesecond-orderequationverywell.ThevaluesofXmweregoethite>kaolinite,andlatosol>redsoilatthesameinitialreactionconcentration.Thevaluesofkwerekaolinite>>goethite,andlatosol>redsoilatthesamereactionpHandinitialconcentration.ThehigherthesuspensionpH,thefastertheadsorptionoccurred.ThemeaningofXmgotbythetwoion-selectiveelectrodetechnique(onekindofbatchtechnique)wasdifferentfromthatbythemiscibledisplacementtechniqueinthattheformerwasonlytheequilibriumadsorptionamountatadefiniteconcentrationandpH,butthelatterwasalmostequaltotheadsorptioncapacityatadefinitepHwithmuchlessinfluenceofconcentration.OnePb^2+wassupposedtooccupytwoadsorptionsitesastheadsorptionmechanismisconcerned.
简介:Metalion-imprintedlycrosslinkedchitosanresin1andresin2werepreparedbytheuseofCu^2+andNi^2+astemplateionsandglutaraldehydeascrosslinkingagent,respectively,ThroughinvestigationontheadsorptioncapactiesandbindingconstantsforCu^2+,Ni^2+andCo^2+ionsonchitosanresins,resin1andresin2exhibittheadsorptionselectivityforthemixturesolutionof1L1Cu^2+andNi^2+ions.Theadsorptionselectivityofmetalion-imprintedresinsfortheirtemplateionsinmuchhigherthanthatofuncrosslinkedchitosanresin.
简介:目的:研究爱大霉素和庆大霉素对大鼠肾皮质内质网^45Ca^2+摄取以及对内质网膜上Ca^2+-Mg^2+-ATPase活性的影响。方法:^45Ca^2+示踪技术和孔雀蓝分光光度法。结果:爱大霉素和庆大霉素在大于或等于3.4×10^-4mol·L^-1时,能抑内质网^45Ca^2+摄取(抑制率分别大于或等于17.4%和25.5%);在3.4×10^-2mol·L^-1时,对内质网膜上Ca^2+-Mg^2+-ATPase活性有抑制作用(抑制率分别为24.17%和29.19%)。结论:爱大霉素和庆大霉素在较高浓度时可使胞浆钙升高,这可能与其产生肾毒性有关。
简介:随着人类老龄化进程的加速,AlZheimer病(AD)逐渐成为老年常见疾病.它有着特有临床和病理特征.然而其病因学机制仍不甚清楚,兴奋性氨基酸毒性学说和钙超载学说日渐为人们所重视.
简介:矿质元素不仅可使植物旺盛、健壮生长,而且多数元素可作为病原物营养需要或毒害作用而影响病原物的侵染扩散和繁殖,增强植物抗病能力。选用番茄灰霉病敏感型番茄L402为试材,叶片施用Ca-(2+)、Mg-(2+)、SA及其组合处理,对番茄五叶幼苗期抗灰霉病的效果进行调查。结果表明:叶面增施Mg-(2+)不显著改变番茄灰霉病的病情指数,病情指数为78.25;Mg-(2+)与SA不同顺序复合施用的病情性指数虽低于对照,但均显著高于SA单一处理;Mg-(2+)不仅没有提高番茄抗灰霉病的作用,也没有提高SA诱导番茄抗灰霉病的作用;Ca-(2+)与SA不同顺序配施对番茄幼苗抗灰霉病的影响效果不同。明确了先施Ca-(2+)再施用SA处理抗病效果最好。即Ca+SA处理的病情指数比SA降低17.93%,比SA+Ca降低13.34%,比单纯施Ca-(2+)降低45.22%;而SA+Ca处理的病情指数与SA处理无显著差异。说明先施Ca-(2+)再施SA,Ca-(2+)具有显著增强SA诱导番茄抗灰霉病的作用。实验结果将有助于了解和提高SA诱导抗性机制,为提高番茄产量和品种提供理论基础和现实依据。
简介:用微波高温固相法合成了Er^3+单掺Lu2O3,Li^+与Er^3+共掺Lu2O3及Li^+,Zn^2+,Mg^2+掺杂Lu2O3∶Er^3+的荧光粉。实验表明金属离子Li^+、Zn^2+、Mg^2+、Er^3+掺杂Lu2O3,不影响Lu2O3的立方晶相。扫描电子显微镜测量表明,Li^+掺杂可以有效改善粉体的分散性和形貌,Li^+,Zn^2+,Mg^2+共掺杂获得的粉体颗粒分布更加均匀,粒径范围为80~100nm。379nm激发下,Li^+与Er^3+共掺样品发光较单掺Er^3+样品在565nm处的发光增强了4.5倍,而Li^+、Zn^2+、Mg^2+与Er^3+共掺样品较其发光增强5.3倍。980nm激发下,Li^+与Er^3+共掺样品,Li^+、Zn^2+、Mg^2+与Er^3+共掺样品的发光分别比单掺Er^3+样品在565nm处发光增强23倍与39倍,在662nm处发光强度分别增强20倍与43倍。379nm激发下,较单掺Er3+的样品,掺杂Li^+的样品和Li^+,Zn^2+,Mg^2+和Er^3+共掺的样品荧光寿命均有所增加,而Zn^2+、Er^3+共掺及Mg^2+、Er^3+共掺样品的荧光寿命则有所缩短。
简介:Emissionquenchingof[Ru(bpy)2(4,4’-dcbpy)](PF6)2(1)bybenzenamine,4-[2-[5-[4-[4-dimethylamino]phenyl]-4,5-di-hydro-1-phenyl-1H-pyrazol-3-yl]-ethenyl]-N,N-dimetyl(2)or1,5-diphenyl-3-(2-phenothiazine)-2-pyrazoline(3)wasobserved.Measurementsoftheemissiondecayof1beforeandafteradditionof2or3bysinglephotoncountingtechniquecon-finnedtheobservations.Theemissionquenchingof1by2or3wassubmittedtoStern-Volmerequation.Itwascalculatedthatthequenchingrateconstants(kq)are5.5×109(mol/L)-1s-1for2and4.0×109(mol/L)-1s-1for3,respectively.Theseresultsindicatedacharacterofdynamicquenchingprocess.Thesinglet-stateof2or3wasalsoquenchedby1.ThequenchingbehaviorsdidnotconformtotheStern-Volmerequationandinvolvedbothstaticanddynamicquenchingprocesses.Theapparentquenchingrateconstant(kapp)wascalculatedtobe3×109(mol/L)-1fortheinteractionofexcited2with1,and1.2×109(mol/L)-1forthatofexcited3wit
简介:将啤酒废酵母制成一种新型的生物吸附剂,用于吸附重金属离子铜。研究了不同温度、时间、pH值,以及铜离子浓度和酵母浓度条件下,啤酒废酵母对Cu^2+的吸附能力。初步确定了啤酒废酵母对Cu^2+吸附的最佳组合,即吸附温度为35℃,吸附时间为55min,起始pH值为5,酵母的质量浓度为1g/L,Cu^2+质量浓度为22mg/L,在此条件下啤酒废酵母对Cu^2+吸附率可达到90.00%左右。通过L16(4^5)正交实验表明,Cu^2+质量浓度和pH值是影响啤酒废酵母吸附铜离子能力的显著因素。对吸附了铜离子的啤酒酵母进行解吸实验,表明在浓度为1mol/L的HCl中,其解吸率为55.00%,与1mol/L的NaOH和去离子水相比,有较高的解吸率。
简介:以土生鳞伞(PholiotaterrestrisOverh.)子实体为生物吸附剂吸附水溶液中的Cd2+,分析吸附剂用量、初始pH值、初始重金属浓度、反应时间这4个因素对吸附的影响,并采用Langmuir和Freundlich等温吸附模型及准一级、准二级动力学模型拟合土生鳞伞的生物吸附特性。结果表明:水溶液中Cd2+的去除率随吸附剂用量和反应时间的增加而增大,当Cd2+的浓度为10g/L时,土生鳞伞子实体吸附剂用量为2g/L,反应2h即可达到平衡吸附,且pH=6时吸附量最大。土生鳞伞子实体对Cd2+的吸附更符合Langmuir平衡模型,相关系数r2>0.99,土生鳞伞子实体对Cd2+的最大吸附量为8.67mg/g。准二级动力学方程比准一级动力学方程能更好地描述土生鳞伞子实体对Cd2+的吸附。
简介:Differentfluxeswereusedtosynthesizelongpersistencephosphors,calciumsulfidesactivatedbyEu2+andTm3+,byconvenientsolid-statemethod.ThephosphorusingNH4Fasafluxhasgoodcrystallinityandlargeparticlesize,itsstabilityagainstwaterandotheratmosphericcomponentsisenhanced,anditsafterglowislongerandfluorescentintensityismoreintensethanthoseofthephosphorusingNH4Clasflux.TheirPLintensitiesvariedwithtimeinmoistairweremeasured,noremarkablechangewasfoundforthosepreparedwithNH4FfluxincontrastwithNH4Clasflux.SousingNH4Fasfluxisagoodmethodtoenhancethestabilityofalkalineearthsulfides.
简介:ZrO2-SnO2compositenanoparticleswerepreparedbyheatingthehydrateprecursorssynthesizedbythechemicalco-precipitationreactionofZrOCl2andSnCl4.Theprecursorswereexaminedbydifferentialthermalanalysis(DTA)andthermogravimetricanalysis(TGA).ThecompositepowderwascharacterizedusingX-raydiffraction(XRD),transmissionelectronmicroscopy(TEM)anddesorptionisotherm(Barrett-Joyner-Halendamethod).Theaveragecrystalsizeofthenanoparticlerangesfrom15to30nmforthesamplecontaining5%-25%ZrO2(massfraction).MostoftheporesintheZrO2-SnO2nanoparficlesareabout10-20nmindiameter.Thecompositepowderispromisingforchemicalsensors.
简介:Differentrareearth(RE)ionsdopantswereaddedintotheSrAl2SiO7:Eu2+phosphorsinordertoenhancethephosphorescenceproperties,andtheeffectoftheREionsincludingYb3+,Ce3+,Nd3+,Dy3+andTm3+,wascomparativelyinvestigated.ItwasfoundthatNd3+additionimprovedthephosphorescencepropertiesobviouslyamongallthestudiedREions.Therefore,Sr1.96–xAl2SiO7:xEu2+,yNd3+phosphorswerestudiedindetail,andtheoptimumEu2+andNd3+concentrationsweredeterminedwiththeafterglowtimeofabout20min.Thephasestructures,photoluminescence(PL)properties,long-lastingphosphorescence(LLP)properties,afterglowdecaycurvesandthermo-luminescence(TL)fortheselectedphosphorsduringthecorrespondingstudywereinvestigated.AllthephosphorsexhibitedgreenPLemissionandLLPemission.ThereweretwoTLbandslocatedatabout325and380Kforthestudiedsamples,andtherelationshipbetweenREadditionandphosphorescencepropertieswasdiscussed.