铋膜电极微分电位溶出法测定环境样品中生物可利用镉

建立了环境样品中生物可利用镉的镀铋膜电极微分电位溶出分析法（DPSA）,考察了同位镀铋膜测定镉的条件。结果表明在HAc—NaAc介质中镉可在镀铋膜电极上得到灵敏的微分电位溶出峰（V=-0．84V）,最低检出质量浓度为0．6μg／L,结合3步连续萃取,利用标准加入法对环境样品中的生物可利用镉进行测定,相对标准偏差2．3％～4.1％,加标回收率97％～104％。     

改性丝光沸石催化二甲醚气相羰化的反应性能

对比研究了铜/钾改性丝光沸石、铜改性丝光沸石、H型丝光沸石上二甲醚气相羰化制醋酸甲酯的反应行为,并通过XRD、NH3-TPD、SEM、TEM及FT-IR等对反应前后催化剂进行了表征分析.丝光沸石负载Cu后,改变了反应过程中催化剂上积炭中间物种的形态,由石墨状"硬碳"转变为易于消除的"软碳"(结焦),从而提高了羰化反应的活性和稳定性;K改性的Cu/MOR沸石,由于K对沸石表面强酸位的调变,抑制了二次反应的发生,进一步提高了二甲醚气相羰化反应的稳定性.     

Synthesis and Crystal Structure of a 2D Cu Framework Constructed from Dinuclear Building Units

A novel 2D Cu coordination polymer [Cu4(pca)4(H2O)2(DMSO)2·2DMSO·2H2O]n(2, H2 pca = pyrazole-3-carboxylic acid) has been prepared by dissolving a dinuclear Cu complex Cu2(py)3(pca)2(H2O)·(H2O)(1) in DMSO solution and structurally characterized by X-ray diffraction. The polymer crystallizes in space group P1 with a = 9.538(3), b = 9.714(3), c = 10.765(3) A, α = 86.492(6), β = 84.007(7), γ = 82.592(6)o, Mr = 1079.04, V = 982.4(5) A3, Z = 1, Dc = 1.824 g/cm3, μ = 2.425 mm-1 and F(000) = 548. The final refinement gave R = 0.0785 and w R = 0.1940 for 2787 reflections with I 2σ(I). The structure of 2 consists of Cu4(pca)4(H2O)2(DMSO)2·2DMSO·2H2O units, which can be viewed as two dinuclear subunits of Cu2(pca)2(H2O)2 and Cu2(pca)2(DMSO)2 connected to each other alternately, with solvent DMSO and H2 O molecules around. The framework features a grid-like topology, with the walls of the grids composed of Cu4(pca)4 units, and the coordinated solvent molecules trapped in the grids.     

甾醇、甾烷醇柱前衍生高效液相荧光分析

采用荧光衍生化试剂2-(9-咔唑)乙酰氯,对天然产物谷甾醇、豆甾醇、菜油甾醇及谷甾烷醇的柱前衍生化条件,包括催化剂的种类、反应温度、衍生化时间等进行了考察,结果表明催化剂选用三乙胺,反应温度80℃,时间20 min,衍生产物具有恒定的最大检测响应值.利用高效液相色谱对衍生产物进行分析,并对衍生物的分离进行了优化选择,达到了较好的基线分离,检出限为12.6～29.5 nmol/L.方法应用于血清样品的测定,谷甾醇、豆甾醇、菜油甾醇和谷甾烷醇的标准加入回收率分别为101.9%、102.4%、101.0%和103.2%.     

基于三苯胺和芴的D—A型高分子信息存储材料的合成及性能

设计和合成了一种高度可溶的基于三苯胺和芴的D—A型高分子信息存储材料PFTD（Poly{[4,4L（4．4’-（9H—fluorene一9,9-diyl）bis（4,1-phenylene））bis（oxy）diphthalonitrile][triphe—nylamine]E9,9-dioctyl-9H—fluorene]}）。随着溶剂极性的增加,荧光强度逐渐减弱,荧光发射谱带变宽且发生红移,最大发射峰分别位于426nm（甲苯）,432nm（四氢呋喃）,r142nm（苯腈）,445nm（N,N-二甲基甲酰胺）。PFTD在THF稀溶液中的绝对荧光量子效率为47．8％,由于固体时强的荧光淬灭效应,旋涂在石英玻璃片上的薄膜绝对荧光量子效率仅为5．5％。通过电化学实验估算得到的HOMO、LUMO、能隙、离子化势和电子亲和势分别为-5．43、-2．62、2．81、5．69、2．88eV。由该聚合物制备的薄膜器件（器件结构：ITO／PFTD／A1）表现出典型的一次写入、多次读出（WORM）型记忆特性,电流开关比大于10^4,开启电压为-1．5V。     

Synthesis and Crystal Structure of Mn（phen）（PhCOO）2（H2O）

1 INTRODUCTION During the last decade the manganese che- mistry has aroused great interest due to its diverse redox functions of enzymes in photosystem Ⅱ and its specially structural, magnetic and spectroscopic properties[1, 2]. A lot of manganese complexes involving carboxylate ligands have been reported, and their properties been fully explored[3, 4]. The coordination environment of the manganese site in biosystem often consists of oxygen and nitrogen atoms from the carboxylate groups…     

数学奥林匹克讲与练(21)

例题讲解１６１．空间中有８个点,其中任何４点不共面,在这些点之间连结１７条线段．求证：（１）至少存在一个由这些线段所构成的三角形;（２）由这些线段构成的三角形实际上不少于４个．证明　（１）由一个已知点所引的已知线段的数目,我们称为这点的“度”．取度最大的一点,设其度为ｎ,则有ｎ条线段由这点引出．如果不存在由已知线段构成的三角形,则这ｎ条线段的另外ｎ个端点之间均无已知线段相连．此外尚余（７－ｎ）个点,每点的度不超过ｎ,故每点至多引出ｎ条已知线段,因而由它们引出的已知线段不超过ｎ（７－ｎ）条,于是已…     

软土地区盾构隧道掘进引起的地表沉降预测修订

在盾构隧道施工时, 地表沉降的Peck公式预测结果往往因地质条件的不同而与实测结果差异较大. 为此研究基于宁波轨道交通1号线地表沉降实测数据, 利用最小二乘和一元线性回归法, 确定了盾构隧道地表沉降槽宽度系数K和地层损失率Vl的取值范围, 并引入了地表最大沉降修订系数α和沉降槽宽度修订系数β对Peck公式进行修订. 结果表明: 宁波软土盾构隧道地表沉降槽宽度系数K范围为0.6~0.9, 建议取0.75, 地层损失率Vl范围为1%~3%, 建议取2%; 当修订系数α取1.2, β取0.8时, 能够获得比Peck公式更好的预测效果.     

Decentralized Cooperation Strategies in Two-Dimensional Traffic of Cellular Automata

We study the two-dimensional traffic of cellular automata using computer simulation. We propose two type of decentralized cooperation strategies, which are called stepping aside (CS-SA) and choosing alternative routes (CS-CAR) respectively. We introduce them into an existing two-dimensional cellular automata (CA) model. CS-SA is designed to prohibit a kind of ping-pong jump when two objects standing together try to move in opposite directions. CS-CAR is designed to change the solution of conflict in parallel update. CS-CAR encourages the objects involved in parallel conflicts choose their alternative routes instead of waiting. We also combine the two cooperation strategies (CS-SA-CAR) to test their combined effects. It is found that the system keeps on a partial jam phase with nonzero velocity and flow until the density reaches one. The ratios of the ping-pong jump and the waiting objects involved in conflict are decreased obviously, especially at the free phase. And the average flow is improved by the three cooperation strategies. Although the average travel time is lengthened a bit by CS-CAR, it is shorten by CS-SA and CS-SA-CAR. In addition, we discuss the advantage and applicability of decentralized cooperation modeling.