Synthesis of CdS nanowires on Cd foil and their photoluminescence properties

Cadmium sulfide(CdS) nanowires were synthesized on Cd foil via a simple solvothermal reaction at 180 ℃ using thiosemicarbazide as the sulfide source and ethylenediamine as the solvent.The CdS nanowires are hexagonal-phase single crystals with an average diameter of 50 nm and length of several microns.The as-prepared CdS nanowires show an absorption peak of around 483 nm in the absorption spectrum.The CdS nanowires exhibit bright photoluminescence(PL) with two distinct emission bands at 503 nm and 697 nm,which shows that the as-prepared CdS nanowires are high-quality nanocrystals.     

酸溶弹溶样—原子吸收光度法测定深海及河沉积物中的镉和铅

以硝酸-高氯酸-氢氟酸混合物在酸溶弹中完全分解深海及河沉积物试样,继在溶液中以火焰原子吸收法测定镉和铅、用NBS标准试样检验,本法具有较好的回收率和重复性。对多种沉积物试样进行分析,其变异系数不大于10％;本法测定结果与烧杯溶样法测定结果进行比较,镉和铅的相对差值均小于10％。     

Uptake and toxic effects of heavy metal ions: Interactions among cadmium,copper and zinc in cultured cells

Summary Absorption of metal ions by KB, HeLa and L-59 cells has been analyzed by atomic absorption spectrophotometry in the course of culture. Ions of the elements of the fourth period in the periodic chart such as Fe(II), Cu(II), Zn(II), Mn(II) and Ni(II) were not taken up, but those of the higher periods, such as Cd(II), Pb(II), Hg(II) and Ag(I) were were taken up easily. The uptake behavior by the cultured cells was in accordance with the characteristic features of metals, that metals in the fourth period are essential elements, and most of the elements of the fifth and the sixth periods are non-essential or toxic elements.The initial rate of Cd(II) uptake and the Cd(II) concentration has a sigmoidal relationship. Cd(II) was absorbed homotropically through cell membranes. The uptake of Cd(II) was specifically inhibited by Cu(II), but was affected little by Zn(II). The toxicity of Cd(II) to KB cells was greatly enhanced in the presence of Cu(II). On the contrary, the toxicity of Cd(II) was reduced by the addition of Zn(II) at several concentrations of Cd(II). The toxicity of Cd(II) did not depend on the amount of Cd(II) absorbed in the cells, but was determined by cofactors such as Cu(II). The interaction between Cd(II) and Cu(II) may be important for Itai-itai disease.     

Cu,Cd对小麦幼苗生长代谢及2种酶活性的影响

通过水培试验研究Cu,Cd对小麦幼苗生长代谢及植物过氧化氢酶和淀粉酶活性的影响.结果表明,培养10 d的小麦幼苗对Cu,Cd的富集量是随着重金属胁迫浓度的增大而增大,重金属胁迫浓度较低时,对小麦幼苗的株高和生物量影响不大,随着浓度增加,小麦幼苗生长明显受抑制;同时小麦幼苗中的过氧化氢酶活性随重金属胁迫浓度增加而上升,淀粉酶活性则先上升后降低.     

锰及锰镉复合污染对锰矿区茶园土壤酶活性的影响

研究广西八一锰矿恢复区茶园土壤重金属(锰、镉)污染浓度与酶活性的关系,并分析锰离子单一处理和锰镉复合处理条件下土壤酶活性的变化情况.结果表明,锰单一污染与锰镉复合污染对土壤酶活性产生的影响有所不同.锰单一污染对锰矿区土壤酶活性的抑制效应顺序为:过氧化氢酶＞蔗糖酶＞脲酶;锰镉复合污染对锰矿区土壤酶活性的抑制效应顺序为:蔗糖酶＞过氧化氢酶＞脲酶.其中,锰镉复合污染对蔗糖酶表现出协同抑制负效应的特征,对过氧化氢酶和脲酶则表现出不同程度的拮抗作用.建议以过氧化氢酶和蔗糖酶的活性作为评价和预测锰矿恢复区茶园土壤锰镉污染状况的敏感指标.     

镉、豆磺隆联合胁迫下黑土质量的变化

采用盆栽试验研究了黑土Cd单一污染和Cd-豆磺隆复合污染胁迫与上壤脲酶、磷酸酶活性的关系,同时分为拔节期、开花期和成熟期三个时期研究了在有或无污染物作用下这2种酶活性的动态变化规律.结果表明,无论是在有或无豆磺隆胁迫下,随着Cd污染浓度的增加,脲酶活性呈现出明显的下降趋势,酸性磷酸酶活性变化相对于脲酶比较稳定.通过拟合方程可知,2种酶活性变化在一定程度上可以反映Cd或Cd-豆磺隆的污染状况.在小麦的整个生长期内,当Cd污染浓度为5、10、30 mg·kg-1时,2种酶活性均呈现先升高后下降的趋势;而在高浓度(50、100mg·kg-1)Cd作用下,2种酶活性始终呈现升高的趋势.     

Microbial activity and community diversity in a variable charge soil as affected by cadmium exposure levels and time

Effects of cadmium （Cd） on microbial biomass, variable charge soil （Typic Aquult） using an incubation study activity and community diversity were assessed in a representative Cadmium was added as CdCNO3）2 to reach a concentration range of 0-16 mg Cd/kg soil. Soil extractable Cd generally increased with Cd loading rate, but decreased with incubation time. Soil microbial biomass was enhanced at low Cd levels （0.5-1 mg/kg）, but was inhibited consistently with increasing Cd rate. The ratio of microbial biomass C/N varied with Cd treatment levels, decreasing at low Cd rate （〈0.7 mg/kg available Cd）, but increasing progressively with Cd loading. Soil respiration was restrained at low Cd loading （〈1 mg/kg）, and enhanced at higher Cd levels. Soil microbial metabolic quotient （MMQ） was generally greater at high Cd loading （1-16 mg/kg）. However, the MMQ is also affected by other factors. Cd contamination reduces species diversity of soil microbial communities and their ability to metabolize different C substrates. Soils with higher levels of Cd contamination showed decreases in indicator phospholipids fatty acids （PLFAs） for Gram-negative bacteria and actinomycetes, while the indicator PLFAs for Gram-positive bacteria and fungi increased with increasing levels of Cd contamination.     

重金属汞和镉对普通小球藻生长的影响

以普通小球藻(Chlorella vulgaris)为研究材料,研究了不同浓度的Hg2+和Cd2+对其生长的影响.结果表明:低浓度(0⁰.50 mg/L)的Hg2+和Cd2+由于毒性兴奋效应能刺激普通小球藻细胞密度的增长,促进叶绿素含量的增加和蛋白质的合成;当Hg2+和Cd2+浓度进一步增加,则抑制普通小球藻的生长;当Hg2+和Cd2+的浓度分别为2 mg/L时,无蛋白积累.     

配聚物[Cd2（2,5-pdc）2（H2O）4]n的光电性能

采用水热合成法,以2,5-吡啶-二羧酸为配体,得到了Cd(Ⅱ)配聚物:[Cd2(2,5-pdc)2(H2O)4]n(2,5-H2pdc=2,5-吡啶-二羧酸).采用X射线单晶衍射确定了配聚物的晶体结构.配聚物的不对称单元为Cd2(2,5-pdc)2(H2O)4,其中两个不等效的金属Cd(Ⅱ)离子均为6配位.在配聚物晶体中,Cd(Ⅱ)离子之间通过pdc2-上的羧基O原子连接,形成了具有2D结构的配聚物,氢键进一步将其连接成3D超分子.采用表面光电压光谱(SPS)研究了配聚物的表面光电性能.结果表明,该配聚物在300~800nm范围内呈现出较强的光伏响应,表明他具有一定的光-电转换能力.对配聚物的UV-Vis-NIR吸收光谱、IR光谱进行了测定和指认,并将SPS谱与UV-Vis-NIR吸收光谱进行了关联.     

Cd3As2弹性模量和热力学性质模拟研究

利用第一性原理结合赝势平面波方法研究了立方(空间群:P4232, No.208)和四方(空间群:P42/nmcs, No.137)Cd_3As_2的晶体结构、状态方程、弹性常数.将晶胞能量-体积关系按Birch–Murnaghan状态方程拟合得到体弹模量及其对压强的一阶导数.另外,根据Voigt–Reuss–Hill关系预测了Cd_3As_2晶体的力学性质.最后,通过准谐德拜模型得到Cd_3As_2晶体在不同温度下的热膨胀系数、绝热体弹模量、晶胞体积和等体热容.