A Microcell for Stripping Analysis with Glassy Carbon and Mercury-Plated Glassy Carbon Electrodes

Abstract

A microcell has been constructed for stripping analysis in solution volumes as low as 5 μl, employing a glassy carbon or mercury-plated glassy carbon working electrodes and a three electrode system. Using normal d.c. stripping techniques, as little as 100 picograms of mercury and 10 picograms of lead can be determined. With the more sensitive second harmonic a.c. voltammetric technique, this limit is lowered to 10 picograms of mercury and 1 picogram of lead.     

胎儿脐带血铅水平与钙、锌、铁的关系研究

目的研究胎儿脐带血中的铅与钙、锌、铁的含量以及两两之间的相关性。方法采用原子吸收光谱法对398例脐带血铅和钙、锌、铁的含量进行测定,并对它们进行相关性分析。结果 398例脐带血铅和钙、锌、铁的质量浓度分别为铅(37.96±17.78)μg/L、钙(1.51±0.29)mmol/L、锌(30.01±11.14)μmol/L、铁(8.63±1.39)mmol/L。线性回归分析显示:铅与钙(r=-0.563,P0.01)、铅与锌(r=-0.424,P0.01)有相关性,铅与铁无显著相关(r=0.018,P0.05)。结论随着胎儿体内血铅水平的上升,二价元素钙、锌含量有下降趋势,即中毒元素铅会干扰胎儿体内的必需二价元素的代谢。     

Mechanochemical synthesis of PbS/Ni–Cr layered double hydroxide nanocomposite

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一类区间不确定时滞系统超前/滞后补偿器设计

针对一类具有全极点的区间不确定时滞系统,给出了相位超前/滞后补偿器的一种图解鲁棒设计方法.对滞后因子采用一阶Pade近似,应用广义Kharitonov定理,证明了图解法设计出的相位超前/滞后补偿器可以镇定区间不确定近似系统.通过仿真验证了该补偿器亦可镇定原区间不确定时滞系统,并保持良好的系统性能.该种图解设计方法选择参数灵活,便于实际应用.     

酒石酸铅锆的制备、表征及其燃烧催化作用

以酒石酸、硝酸氧锆和硝酸铅为原料,合成出了双金属盐酒石酸铅锆,采用有机元素分析、X射线荧光光谱和FTIR对其进行了表征。在程序升温条件下,利用TG/DTG、DSC、固相原位反应池/FTIR联用技术,研究了酒石酸铅锆的热行为和热分解机理,描述了酒石酸铅锆的热分解过程,分析得出其最终分解产物为ZrO2、PbO和C。利用螺压工艺制备了含酒石酸铅锆的推进剂样品,研究了酒石酸铅锆对双基系推进剂燃烧性能的影响,分析了其燃烧催化作用。结果表明,酒石酸铅锆对双基系推进剂的燃烧具有良好的催化作用,是一种高效的燃烧催化剂;酒石酸铅锆热分解的最终产物PbO是催化燃烧的主要活性物质,推进剂燃烧过程中形成了氧化铅-铅循环催化体系,而锆和碳则起辅助催化的作用。     

营养素与亚临床铅中毒的防治

营养素能有效防治亚临床铅中毒,阐述了钙、铁、锌、硒及维生素等营养素与铅毒性作用的相互关系。     

微波消解–石墨炉原子吸收法测定化妆品中的铅

建立了微波消解–石墨炉原子吸收光谱法测定化妆品中铅的方法。探讨了样品前处理条件、基体改性剂的选择和优化、石墨炉升温条件等对测定结果的影响。在优化的试验条件下,铅的质量浓度在0~100 ng/mL范围内与吸光度具有良好的线性关系,线性相关系数r=0.9991,检出限为0.33 ng/mL。用该法对5种化妆品中的铅进行测定,加标回收率在95.0%~106.1%之间,测定结果的相对标准偏差不大于3.6%。该方法可应用于化妆品中痕量铅的分析。     

应用多接收器电感耦合等离子体质谱法测定海洋碳酸盐中稳定铅同位素组成

研究了多接收器电感耦合等离子体质谱仪(MC-ICP MS)测定铅同位素比值时,影响测试结果准确度和精密度的主要因素及其优化过程。在优化条件下,10 h内连续30次测定4 ng/mL NIST SRM 981同位素标准溶液铅同位素比值,获得208Pb/206Pb、207Pb/206Pb和206Pb/204Pb相对标准偏差(RSDs)分别为0.005%、0.004%和0.054%。长期监测208Pb/206Pb、207Pb/206Pb和206Pb/204Pb,标准偏差(2SDs)分别为0.000 06、0.000 05和0.006 7。采用NEPTUNE MC-ICP MS法测定了低铅海洋碳酸盐样品中稳定铅的同位素比值,并对南海橙黄滨珊瑚(Porites lutea)和库氏砗磲(Tridacna gigas)进行了分析,得到全流程空白为8～10 pg,重复样误差优于0.1%。经0.50 mol/L HNO3洗脱之后,得到海南珊瑚样品中208Pb/206Pb、207Pb/206Pb的比值分别为2.086 2±0.001 5、0.849 90±0.001 47(n=16);海南砗磲样品中208Pb/206Pb、207Pb/206Pb的比值分别为2.116 9±0.004 2、0.864 81±0.001 62(n=9)。进一步考察了南海海洋碳酸盐中204Pb的同位素比值。分析结果表明,南海海洋碳酸盐中稳定铅同位素比值与中国气溶胶、珠江三角洲大气沉降、黄土及南海海底玄武岩等具有很好的相关性。方法适用于复杂基体高钙低铅的海洋碳酸盐样品中铅同位素比值的分析。     

FEW: A workflow tool for free energy calculations of ligand binding

In the later stages of drug design projects, accurately predicting relative binding affinities of chemically similar compounds to a biomolecular target is of utmost importance for making decisions based on the ranking of such compounds. So far, the extensive application of binding free energy approaches has been hampered by the complex and time‐consuming setup of such calculations. We introduce the free energy workflow (FEW) tool that facilitates setup and execution of binding free energy calculations with the AMBER suite for multiple ligands. FEW allows performing free energy calculations according to the implicit solvent molecular mechanics (MM‐PB(GB)SA), the linear interaction energy, and the thermodynamic integration approaches. We describe the tool's architecture and functionality and demonstrate in a show case study on Factor Xa inhibitors that the time needed for the preparation and analysis of free energy calculations is considerably reduced with FEW compared to a fully manual procedure. © 2013 Wiley Periodicals, Inc.     

Syntheses,Structures, Luminescent Properties and Photocatalytic Activities of Two Lead（II） Compounds

Two lead（ll） compounds, [Pb（qlc）（phen）2（NO3）]e-H20 （1） and [Pb（qlc）z（phen）]-3H20 （2） （Hqlc = quinoline-3-carboxylic acid, phen = 1,10-phenanthroline）, were synthesized and charac- terized by elemental analysis, single-crystal X-ray diffraction, IR and thermogravimetric analysis. Crystal 1 is of monoclinic, space group C2/c with a = 25.246（5）, b = 12.543（3）, c = 18.917（4） A, β = 105.77（3）°, V= 5765（2） A3, Z = 4, C68H46N12OllPb2, Mr = 1621.53, Dc = 1.886 g.cm-3,/.t（MoKa） = 5.912 mm-1, F（000） = 3152, GOOF = 1.080, the final R = 0.022 and wR = 0.0571 for 4822 observed reflections （1 〉 2a（/））. Crystal 2 is oftriclinic, space group Pi with a = 8.7883（10）, b = 11.7031 （13）, c = 15.9320（17） A, a = 69.9400（10）, fl = 78.9780（10）, 7 = 79.1650（10）°, V = 1497.4（3） A3, Z = 2, C32H26NaO7Pb, Mr. = 785.71, Dc = 1.729 g.cm-s, p（MoKa） = 5.688 mm-1, F（000） = 756, GOOF = 1.106, the final R = 0.0313 and wR = 0.088 for 59i5 observed reflections （1 〉 2σ（I））. Single-crystal X-ray diffraction analysis reveals that 1 exhibits a two-dimensional （2D） layer based on π-π stacking interactions between phen. Simultaneously, the adjacent 2D layers are assembled via π-π stacking interactions between phen and quinoline tings into a 3D supramolecular structure. The zero- dimensional structure of 2 is also further extended by π-π interactions to form a 2D supramolecular layer. Furthermore, these two compounds exhibit photoluminescence at room temperature in the solid state and their photocatalytic activities have been studied by degradation methylene blue.