Layer-by-layer self-assembled ultrathin multilayer films of lanthanide polyoxometalates and poly(allylamine hydrochloride) and their photoluminescent properties

Ultrathin multilayer films of two lanthanide polyoxometalates (LPOMs), K(17)[Eu(P(2)W(17)O(61))(2)] (EPW) and K(13)[Eu(SiW(11)O(39))(2)] (ESW), and poly(allylamine hydrochloride) (PAH) have been prepared by layer-by-layer self-assembly from dilute aqueous solutions. UV-vis spectroscopy and ellipsometry respectively show that the absorbance values at characteristic wavelengths and the thicknesses of the multilayer films increase linearly with the number of LPOM/PAH bilayers, suggesting that the deposition process is linear and highly reproducible from layer to layer. Average thicknesses of ca. 3.4 and 2.4 nm were determined for the EPW/PAH and ESW/PAH bilayers by ellipsometry, respectively. In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) images provide the surface morphology of the LPOM/PAH films, indicating that the film surface is relatively uniform and smooth. The photoluminescent properties of these films have also been investigated by fluorescence spectroscopy. The LPOM/PAH multilayer film has a good thermal stability as shown by UV-vis, X-ray photoelectron, and fluorescence spectra.     

Enzymatic synthesis of phosphocarnitine, phosphogabob and fosfomycin

Phosphocarnitine was conveniently obtained from easily available diethyl 3-chloro-2-oxopropanephosphonates, followed by subsequent reduction, Mucor miehei lipase (IM) mediated resolution, amination and dealkylation. Candida antarctica lipase B (CALB) served as an effective biocatalyst in the resolution of several 1- or 2-hydroxyalkanephosphonates. The chlorine atom in different positions on the molecules greatly affected their enantioselectivity. CALB also showed satisfactory enantioselectivity toward those molecules bearing an azido moiety. Both enantiomers of phosphogabob and fosfomycin were also prepared via CALB-mediated resolution as the key step.     

A study of two geometric isomers of 1,1′-bi-3-cyanocyclohex-2-enylidene

The preparation, separation, crystal structure and ¹H NMR spectra are reported for the two geometrical isomers of 1,1-bi-3-cyanocyclohex-2-enylidene. The E-isomer crystallized as thin plates in the monoclinic space group P2₁/n with a = 5.3980(5), b = 7.0757(7), c = 15.300(2) Å, = 94.571(2)°, and Z = 2. The structure has symmetry C_2h. The Z-isomer crystallized as needles in the triclinic space group P1¯ with a = 7.0790(6), b = 11.3155(9),c = 15.386(1) Å, = 104.943° = 90.164(2)°, = 99.494(2)°, and Z = 4. The compound crystallized with two molecules per asymmetric unit. In C₆D₆, ¹H NMR signals of the 2-vinyl protons appear almost identical. However, in a mixture of C₆D₆ and pyridine-d ₅, the 2-vinyl protons can be distinguished. The structures compare favorably with MM2 calculations.     

LARGE-STRAIN CONSOLIDATION OF FOUNDATION WITH SAND DRAINS BASED ON HANSBO'S FLOW 1)

基于Gibson大变形固结理论,通过引入Hansbo渗流模型和软黏土非线性变形特性,同时考虑土层的沉积效应,分别建立了以孔隙比$e$和超孔压$u$表示的砂井地基大变形固结方程。通过与已有研究成果的对比,验证了本文方法的可靠性和砂井地基大变形固结方程两种描述方式的等效性。通过FlexPDE得到方程的数值解,在此基础上,研究了砂井地基大、小应变固结理论与Barron固结解的差异性,探讨了Hansbo渗流参数$m$和$I_1$对砂井地基固结的影响,最后对比分析了砂井地基轴对称固结、径向固结和竖向一维固结的关系。研究结果表明：考虑Hansbo渗流的砂井地基非线性大变形固结模型的固结速率最慢,且在固结后期,Hansbo渗流时大、小应变固结与Barron固结的平均固结度基本趋近;随着Hansbo渗流参数$m$和$I_1$的逐渐增大,砂井地基的固结速率逐渐降低;随着砂井影响半径的增大,砂井地基轴对称固结与径向固结的差异性也越来越大,且在固结早期会出现一维竖向固结速率高于轴对称固结和径向固结的现象。     

螯合剂与牛血清白蛋白竞争镉作用的研究

研究了十一种螯合剂使结合在牛血清白蛋白(BSA)上的镉活动化的能力。由凝胶色谱法测得的F值将螯合剂活动镉的能力排成以下顺序:DTP>EDTA>EGTA>NTA>TRIEN>;PEN>CYS>HIS>SA氨羧络合剂型配体能有效地与BSA竞争,而且它们的lgF与lgK_CdL间有一线性关系。     

将门虎子——2006年度诺贝尔化学奖简介

2006年10月,瑞典皇家科学院将2006年诺贝尔化学奖授予美国斯坦福大学的罗杰.D.科恩伯格教授,表彰他在揭示真核细胞转录的分子机制方面的杰出贡献。罗杰.科恩伯格的父亲阿瑟.科恩伯格也曾在1959年因为解析DNA复制机理而获得诺贝尔生理学和医学奖。罗杰早在高中时代就决心投身科学,最终以他过人的天赋、诺贝尔奖家庭的科学熏陶和持之以恒的努力,成为揭开真核基因转录分子机制的科学巨匠。罗杰的科学经历和成就应验了中国的一句古话:“将门虎子”。图1科恩伯格父子罗杰.D.科恩伯格(Roger D Kornberg)1947年出生于美国密苏里州的圣路易斯,先…     

固相萃取-电感耦合等离子体质谱（ICP-MS）法测定海水中6种金属元素

为了实现海水中金属元素的绿色分离和快速检测,建立了新型螯合树脂为填料,固相萃取-电感耦合等离子体质谱（ICP-MS）测定海水中6种金属元素含量的方法。海水中Cu,Pb,Co,Ni,Cr,Mo金属离子与亚氨基二乙酸型螯合树脂形成螯合物,经固相萃取、洗脱,实现金属离子从海水中定量分离富集。在最佳实验条件下,测得方法的相对标准偏差（RSD）为1.7 %～3.6 % ,加标回收率为82.6 %～102 %,检出限为0.03 μg /L～0.15 μg /L。本研究采用亚氨基二乙酸型螯合树脂为填料的固相萃取,实现了海水分析的绿色样品前处理方法,与ICP-MS相结合用于海水标准样品和实际样品的分析,获得了满意的结果。     

关于小投射模

本文利用小投射模刻划了左V—环并研究了补小投射模的性质,给出其自同态的构造,推广了的主要定理l.15.     

Novel anion-exchange organic–inorganic hybrid membranes: Preparation and characterizations for potential use in fuel cells

A new series of supported anion-exchange organic–inorganic hybrid membranes were prepared by quaternizing the copolymer of vinylbenzyl chloride (VBC) and γ-methacryloxypropyl trimethoxy silane (γ-MPS) and then applying a sol–gel reaction to the copolymer and monophenyltriethoxysilane (EPh). The membranes were characterized for potential use in fuel cells. The results show that the physicochemical properties, including ion-exchange property, hydrophilicity, and thermal/chemical stability, can be easily controlled by adjusting the quaternization extent of the copolymer and the dosage of EPh. The hybrid membranes have relatively strong alkali resistance, high temperature tolerance (thermal degradation temperature in air, Td, in the range of 250–300 °C), high tensile strength (TS) and elongation at break (E_b). The hydroxyl ion conductivity is in the range of 2.27–4.33 × 10⁻⁴ S/cm.