Comparison of heavy metal accumulation by a bloom-forming cyanobacterium, Microcystis aeruginosa

Microcystis aeruginosa is the dominant species during cyanobacterial blooms in freshwater lakes. In the present study, we compared the bioaccumulation characteristics of cadmium (Cd) and zinc (Zn) in Microcystis cells. In short-term uptake tests, a rapid sorption of Cd and Zn occurred in the first few minutes, with a subsequent slower internalization process. No obvious difference was observed between Zn and Cd in terms of their short-term uptake kinetics. In efflux experiments, elimination of Zn from the cells was faster than that of Cd. In the 72-h exposure tests, the intracellular Cd concentrations increased with exposure time whereas the intracellular Zn concentrations always reached a plateau. The cellular Cd showed greater variation than the cellular Zn at various free Cd²⁺ or Zn²⁺ concentrations. The differences in Cd and Zn accumulation and elimination indicated that Microcystis cells had a higher bioaccumulation capacity for Cd than for Zn. In field studies, the bioconcentration factor (BCF) of Cd in lake-harvested Microcystis was more than 10 times higher than those of other metals. The results of the present study strongly suggested that the bloom-forming Microcystis may affect the Cd transportation and biogeochemical cycling in eutrophic freshwater ecosystems.     

磁场处理对酿酒酵母微观结构及细胞膜流动性的影响及作用机理.

摘要：以磁场为外加物理场,采用恒定磁场及循环磁处理方式对酿酒酵母进行磁处理,研究酿酒酵母微观结构及细胞膜流动性的变化。通过透射电子显微镜,观察不同磁感应强度恒定磁场处理后酿酒酵母的微观结构,发现恒定磁场可以促进酵母细胞的生长,群体中以具有中央大液泡为特征的成熟细胞所占比率增大,同时线粒体呈现适应性膨大、增生。以原子力显微镜观察循环磁处理下酵母细胞的三维结构,发现细胞壁表面出现皱缩、穿孔,胞质外流,证实循环磁处理具有脉冲磁场的特征,可产生瞬间高能作用于细胞,从而产生致死效果。用荧光偏振法对两种处理方式下细胞的膜脂流动性进行测定,发现不同强度恒定磁场处理后,膜脂各向异性下降,流动性增强,0.05T磁感应强度下各向异性值下降3.57%,而循环磁处理后各向异性值比对照提高了8.46%,膜脂流动减慢,证实细胞膜为磁场作用的一个靶点。     

Point defects in active layers of TFEL devices based on ZnS

Point defects in the active layer of a layered optimization thin film electroluminescent device of ZnS; Er³⁺ were studied. The results indicate that besides Er³⁺ substituting for Zn²⁺ as luminescent centers, the dominant point defects are sulfur vacancies, zinc vacancies, shallow donors and deep acceptors. Their influence on electroluminescence is discussed.     

从无铁渣湿法炼锌流程还原补锰液中萃取铟

考察了P₂0₄对Fe²⁺，Mn²⁺，Zn²⁺及In³⁺的硫酸盐模拟溶液中各种金属离子的萃取性能，然后对真实溶液无铁渣湿法炼锌流程中高酸浸出液的还原补锰液中的铟进行萃取分离.确定了萃取分离铟的最佳条件为：(ⅰ)有机相组成分为30%P₂0₄+70%磺化煤油；（ⅱ）温度20　℃±；（ⅲ）级数3级；（ⅳ）相比O/A=3∶1；（ⅴ）时间5　min，在最佳条件下，铟的萃取率≥99.4%，P204对In³⁺，Zn²⁺，Mn2⁺　３种金属的萃取饱和容量分别为54.0　g·L^-1，22.0　g·L^-1和2.0　g·L^-1，全流程铟的直收率达到77.58%，总回收率≥95.0%，比传统提取铟流程回收率提高20%以上.     

Y2O2S:Eu3+,Zn2+,Ti4+荧光体的缺陷及红色长余辉发光性质

采用高温固相法合成了红色长余辉材料Y2O2S:Eu3+,Zn2+,Ti4+,实现了余辉发光中心和缺陷中心之间的能量传递。通过XRD、荧光发射和激发光谱、余辉发射光谱与衰减曲线、色坐标和热释光谱测试手段对Y2O2S:Eu3+,Zn2+、Y2O2S:Eu3+,Ti4+、Y2O2S:Eu3+,Zn2+,Ti4+和Y2O2S:Eu3+,Mg2+,Ti4+进行了结构与性能的表征,发现其荧光发射与余辉发射基本一致,红色余辉发光主峰位于625 nm附近,来源于Eu3+的5D0→7F2跃迁发射。相比而言,Y2O2S:Eu3+,Zn2+,Ti4+余辉发光性能最好,可持续1.5 h左右。     

Zn2+对果蝇生育力和寿命及抗氧化能力的影响

为了研究Zn~(2+)对果蝇生育力和寿命及抗氧化能力的影响。以黑腹果蝇(Drosophila melanogaster)为研究动物,用生存实验来考查不同浓度的Zn~(2+)处理果蝇,研究果蝇F1-F4代生育力和寿命的变化,雌、雄果蝇数量的变化,抗氧化酶SOD、CAT的活力及MDA含量的变化。结果显示:添加Zn~(2+)浓度为1.0 g/mL可以使F1-F4代雌、雄果蝇世代生育力增强,寿命延长,而在Zn~(2+)浓度为2.0×10-3g/mL时果蝇体内MDA含量大量积累,SOD和CAT活性急剧降低,使果蝇提前衰老、死亡并且降低或丧失生殖能力,而Zn~(2+)对果蝇性别分化影响不大,总体接近于1:1。因此,适当浓度的Zn~(2+)可以延长果蝇寿命,增强其生殖力,提高抗氧化能力。     

The mitochondrial function was impaired in APP knockout mouse embryo fibroblast cells

The amyloid precursor protein (APP) is recognized as the source of Aβ, which plays an important role in Alzheimer’s disease. However, the biological function of APP is obscure. Previous studies showed that mitochondria could be a target of APP. In this work, APP knockout mouse embryo fibroblast (MEF) cells were used to test if APP plays any role in maintaining the mitochondrial function. As the result, APP knockout MEF cells (APP-/- cells) showed the abnormal mitochondrial function, including slower cell pr...     

Cu2+和Zn2+对模拟胃液中NDMA形成的影响

【目的】在模拟胃液条件下研究重金属Cu~(2+)和Zn~(2+)对内源致癌性N-二甲基亚硝胺(NDMA)形成的影响,并进一步探讨其作用机理。【方法】分别用气相色谱-质谱联用法(GC-MS)和离子色谱法(IC)来测定NDMA、二甲胺(DMA)和亚硝酸根(NO_2~-)含量。【结果】在模拟胃液条件下,Cu~(2+)和Zn~(2+)浓度高于50mg/L时,可以促进NDMA的形成,且当浓度由50mg/L增大到200mg/L时,Cu~(2+)促进率由1.16%增大到94.56%,Zn~(2+)促进率由21.32%增大到45.86%。在重金属浓度为符合或接近符合水质基准值1.0mg/L时,Cu~(2+)和Zn~(2+)对NDMA的形成也分别有16.88%和13.42%的促进率;而当重金属浓度为10mg/L时,两种离子却均抑制NDMA的形成。机理研究表明Cu~(2+)、Zn~(2+)促进NDMA的形成主要是由于其与DMA发生相互作用,进而导致NDMA形成。【结论】高浓度的Cu~(2+)和Zn~(2+)通过与DMA相互作用,形成活性中间体从而促进NDMA的生成。     

SIOC-AA-005的抗肿瘤作用机制研究

探讨SIOC-AA-005抗肿瘤的作用机制.采用测定HT-29 细胞线粒体膜流动性、线粒体ATP含量、线粒体ATP酶活性及NADH-CoQ氧化还原酶活性、细胞质膜NADH氧化酶活性的方法,对其作用机制进行了深入探讨;SIOC-AA-005在10 nmol/L剂量下可明显降低线粒体膜的流动性,并使线粒体膜电位显著升高;在此浓度下,SIOC-AA-005还可使HT-29细胞内的ATP耗竭,ATP酶活性受到抑制,线粒体中能量产生过程受阻.在胞外反应体系中,SIOC-AA-005对NADH-CoQ氧化还原酶有强烈的抑制作用,对细胞质膜NADH氧化酶也具有较强的抑制作用.SIOC-AA-005可能是通过抑制线粒体NADH-CoQ氧化还原酶、抑制细胞质膜NADH氧化酶以及线粒体ATP酶活性,从而使线粒体膜流动性下降,膜电位升高,细胞内ATP耗竭,最终使肿瘤细胞死亡。     

金属离子对钢在没食子酸/硫酸介质中的腐蚀行为研究

 用失重法研究了4种金属离子(Na⁺,Zn²⁺,Cu²⁺,Fe³⁺)在0.5 mol/L H₂SO₄以及500 mg/L没食子酸+0.5 mol/L H₂SO₄介质中在20℃对冷轧钢腐蚀行为的影响.结果表明:Cu²⁺对钢的腐蚀起抑制作用;而其余3种金属离子(Na⁺,Zn²⁺,Fe³⁺)对钢的腐蚀起加速作用.在相同条件下,冷轧钢在0.5 mol/L H₂SO₄溶液中的腐蚀速率顺序为:Cu²⁺2++3+;而在500 mg/L没食子酸+0.5 mol/L H₂SO₄介质中,腐蚀速率顺序为:Cu²⁺2+3++.     

沉淀法制备纳米钛酸锌粉体的研究

文中以TiCl₄和ZnCl₂的混合液为原料液、以NaOH为沉淀剂,采用直接沉淀法,在不同沉淀剂的质量浓度(3,6,9mol/L)以及Zn²⁺与Ti⁴⁺的摩尔比为1∶1.2～2∶1的条件下,通过煅烧,得到粒径小于100nm的立方相钛酸锌粉体。研究结果表明：沉淀剂NaOH浓度为3mol/L,Zn2+与Ti⁴⁺的摩尔比为1∶1时,经600℃煅烧得到粒径约为40nm的纯立方相ZnTiO₃粉体;Zn²⁺与Ti⁴⁺的摩尔比为2∶1时,经800℃煅烧得到粒径约90nm的Zn₂TiO₄粉体。粉体形貌为球形,粒度分布窄。     

硅藻土对锌离子的吸附特性

研究了吉林长白硅藻土吸附水相中锌离子的吸附过程,讨论了各试验因素对吸附效果的影响·实验结果表明:吉林长白硅藻土对Zn2+有较好的吸附效果·该吸附过程进行得很快,10min左右即可达到吸附平衡·与酸性条件下的吸附效果相比,pH在中性条件下的吸附效果更佳·温度对吸附效果影响较大·对锌离子质量浓度为9 8mg/L的溶液,硅藻土用量为10g/L时Zn2+的去除率达到99 71%·经过硅藻土二次吸附后,锌离子去除率接近100%·经扫描电子显微镜的测定,硅藻土的表面圆筛形微孔是Zn2+的主要吸附位·     

Mitochondrial response and calcium ion change in apoptotic insect cells induced by SfaMNPV

Mitochondrial responses and changes of calcium ions in apoptotic insect SL-1 cells induced by Syngrapha falcifera multiple nuclear polyhedrosis virus (SfaMNPV) are reported in this paper. By using Rhodamine 123 as a fluorescent labeling probe, flow cytometry analysis and confocal laser scanning microscope observation we observed that the mitochondrial transmembrane potential (△ψm) began to decrease in SL-1 cells at 4 h post infection and △ψm reduced continuously with the extension of virus infection. Western blotting indicated that the Bcl-2 level in the mitochondria gradually declined and was down- regulated. Cells undergoing apoptosis were found to have an elevation of cytochrome c in the cytosol and a corresponding decrease in the mitochondria, which indicated that cytochrome c was released from mitochondria into cytosol. These results suggest that mitochondrion-mediated apoptotic signal transduction pathway exists in apoptotic insect cell induced by SfaMNPV. Cytosolic free calcium ([Ca^2 ]i) concentration rapidly increased after SfaMNPV infection and the elevated calcium was tested to come partly from extracelllular calcium ion influx. Flow cytometry analysis indicated that the apoptosis in SL-1 cells was not influenced by established cytosolic calcium clamped conditions and the EGTA inhibiting calcium influx. Therefore, neither the elevation of cytosolic calcium ion nor extracellular calcium entry was the inducing factor of apoptosis, which hinted that the depletion of ER Ca^2 store contributed to SL-1 cell apoptosis induced by SfaMNPV.     

Photoluminescence of ZnO nanorods grown by hydrothermal method on Si substrate

ZnO nanorods were grown on Si substrate by hydrothermal method under various reaction time (12, 24, and 36 h), Zn²⁺ concentrations (0.01, 0.02, and 0.05 mol/L) and reaction temperatures (70–95 °C). Their photoluminescence (PL) tests were taken at room temperature. Nanorods grown under longer reaction times or higher temperatures can emit stronger UV light and depressed green light, suggesting better crystallization of ZnO nanorods. Higher Zn²⁺ concentration results in stronger green band emitting, whereas the UV peak is depressed with the Zn²⁺ concentration over 0.02 mol/L. This indicates that excessive interstitial Zn defects may be introduced into the nanorods in Zn-rich environment.     

Ferromagnetism at 230 K in （Ba0.7K0.3）（Zn0.85Mn0.15）2As2 diluted magnetic semiconductor

We report the ferromagnetism with Cure temperature Tcat 230 K in a new diluted magnetic semiconductor(DMS)(Ba0.7K0.3)(Zn0.85Mn0.15)2As2isostructural to ferropnictide 122 superconductors synthesized via low temperature sintering.Spin is doped by isovalence substitution of Mn2+for Zn2+,while charge is introduced by heterovalence substitution of K1+for Ba2+in(Ba0.7K0.3)(Zn0.85Mn0.15)2As2DMS,being different from(Ga,Mn)As where both spincharge are induced simultaneously by heterovalence substation of Mn2+for Ga3+.The(Ba0.7K0.3)(Zn0.85Mn0.15)2As2DMS shows spontaneous magnetization following T3/2dependence expected for a homogeneous ferromagnet with saturation moment 1.0μB for each Mn atom.     

Synthesis and characterization of new calix[4]arene amino acid ester derivatives and their metal extraction properties

A new type of calix[4]arenes containing amino acid ester derivatives has been synthesized. Their¹H NMR characteristics are discussed. Metal ion extraction experimental has shown that calix[4]arene amino acid esters (2a, 2b) possess good extraction efficiency for transition metal ions (Cu²⁺, Ni²⁺, Zn²⁺) and poor extraction efficiency for alkali metal ions (Na⁺, K⁺). Foundation item: Supported by the Ziqang Science Foundation of Wuhan University Biography: MENG Ling-zhi(1947-), female, Associate professor.     

Electrochemical studies of glutathione monolayer assembled on a polycrystalline gold electrode

The glutathione (GSH) monolayer and complex monolayer of GSH-metallic ion on polycrystalline gold electrode were studied by using K₃Fe(CN)₆ as the redox probe. As for the GSH monolayer, it was found that the metallic ions could open the ion-gate in the monolayer dramatically in the order La³⁺> Pb²⁺>>Ba²⁺>Ca²⁺ whereas Zn²⁺ ion closed the ion-gate. The complexes of GSH-metallic ions were capable of self-assembling the different kind of monolayer. All the differences were related to the structural configuration of the anchored GSH molecule, which changed with different metallic ions or pH. Biography:Fang Cheng (1971-) male, Ph. D, research direction: electroanlysis.     

Subsolidus phase relations in the system MgO-ZnO-SiO2 at high pressure

The subsolidus phase relations were determined experimentally in the system MgO-ZnO-SiO2 at 1.0 GPa and 1 200℃, by use of the high-pressure apparatus "piston-cylinder". The results showed characteristics of the phases assemblage different from that in similar ternary systems. It is impossible to form complete Mg2SiO4-Zn2SiO4 olivine and Mg2Si2O6-Zn2Si2O6 pyroxene solid solution. This is controlled by the properties of Zn2+ with an outer layer of electron (Ar)3d10, different from others transition metal ions, like Fe2+ , Ni2+ , Co2+ .