Determination of Utratrace Silver Using Surfactant As Sensitizer by Catalytic Near Field Laser Thermal Lens Spectrometry

Thermal lens spectrometry (TLS) is an excellent tool for trace analysis1. TLS allows the detection of absorbances of 10-7～10-8, concentration of ≈ 10-11 mol稬-1 and the analysis of 10-15 L volumes with ≈10-2 absorbing molecules2. Kinetic analysis is playing an increasingly important part in modern analytical chemistry. Therefore, TLS shows much promise in combination with kinetic analysis. However, there are few data on TLS applications in kinetic analysis method so far3～4. A ne…     

Dispersion state and catalytic properties of vanadia species on the surface of V_2O_5/TiO_2 catalysts

The dispersion state and catalytic properties of anatase-supported vanadia species are studied by means of X-ray diffraction (XRD), laser Raman spectroscopy (LRS), H2 temperature-programmed reduction (TPR) and the selective oxidation of o-xylene to phthalic anhydride. The almost identical values of the experimental dispersion capacity of V2O5 on anatase and the surface vacant sites available on the preferentially exposed (001) plane of anatase suggest that the highly dispersed vanadium cations are bonded to the vacant sites on the surface of anatase as derived by the incorporation model. When the loading amount of V2O5 is far below its dispersion capacity, the dispersed vanadia species might mainly consist of isolated VOx species bridging to the surface through V-O-Ti bonds. With the increase of V2O5 loading the isolated vanadia species interact with their nearest neighbors (either isolated or polymerized vanadia) through bridging V-O-V at the expenses of V-O-Ti bonds, resulting in the increase of the ra     

二芳基乙烯类光致变色材料的合成概述

由于具有多种潜在的应用价值, 光致变色化合物作为高级功能材料的研究在国内外广受关注. 在众多的有机光致变色化合物中, 二芳基乙烯特别是二噻吩乙烯, 由于其具有良好的热稳定性和优良的耐疲劳度而成为这类化合物的杰出代表. 近年来, 有关二芳基乙烯类光致变色化合物的各种合成及性能方面的报道已涉及到信息存储、分子开关、逻辑电路、液晶显示、磁性材料等众多领域. 主要是从有机合成的角度, 对这类材料的合成进行了较为全面的概括, 对各种合成方法分别加以介绍和分析, 对其发展趋势予以探索和展望.     

交流示波极谱法中i_f～E曲线的研究 Ⅳ.示波极谱氧化还原滴定法

在i_f～E曲线的测量方法中,由于氧化和还原剂都具有电化学活性,因此,这两种试剂的量就可以通过不同电极电位处的法拉第电流峰敏锐地反映出来。当利用i_f～E曲线指示氧化还原滴定终点时,终点的示波图形,不仅反映氧化和还原剂电流峰的出现和消失,而且反     

CuO-BaO/SiO2催化剂的结构表征

以XRD、XPS和EXAFS手段对CuO－BaO／Sic2催化剂及其还原态的结构进行了研究．结果表明，在CuO－BaO／SiO2体系中铜和钡都是以氧化态的形式存在，超细SiO2载体对所负载的CuO的结构有影响．随着样品负载量的逐渐降低，Cu－O和Cu－Cu睡的健长和配位数逐渐征小，而且低载量样品的健长和配位数减小的幅度最大．在总负载量＞13．39％的样品中，CuO以晶相的形式存在；总负载量＜13．39％的样品中，CUO呈现单层分布的高分出状态．还原态样品中钢以本价铜的形式存在，随负载量的降低，还原态Cu－Cu健的镇长和配位数也分别呈现出逐渐减小的趋势．还原态中心铜原子在催化剂表面的分布状态基本上保持了氧化态催化剂中CuO物相的分市状态．     

The role of myeloperoxidase and superoxide anion in the luminol- and lucigenin-dependent chemiluminescence of human neutrophils

The amount of chemiluminescence (CL) or light that is emitted from human polymorphonuclear leukocytes (PMN) during phagocytosis or activation by soluble stimuli is dependent on the emission of photons from the oxidation of particulate or bystander molecules. Because the compounds luminol and lucigenin yield photons with high quantum efficiency these agents have been introduced to sensitively assess PMN-CL. Since there is limited information about the pathways involved in the chemiluminescence of these compounds, we investigated the role of both myeloperoxidase (MPO) and superoxide anion (· O₂^?) in luminol-and lucigenin-PMN-CL. We compared the CL between normal and MPO- deficient PMN using zymosan for phagocytosis and N-formylmethionyleucylphenylalanine (FMLP) as a soluble stimulus. Our data demonstrated that luminol-CL was dependent on the presence of MPO and independent of · O₂^? generation during phagocytosis but independent of MPO during FMLP activation. In contrast lucigenin-CL was independent of MPO during both phagocytosis and FMLP activation and appeared to reflect · O₂^? production. Consequently, dependent on the type of activation, it appears that luminol- and lucigenin-CL are generated via different oxidative pathways and may serve as potentially useful tools to differentiate the redox activity of phagocytic cells.     

Synthesis of fused bicyclic pyridines with microwave-assisted intramolecular hetero-Diels-Alder cycloaddition of acetylenic pyrimidines

A series of acetylenic pyrimidines was synthesized and subjected to microwave irradiation. In contrast to conventional heating, the microwave irradiations generally gave clean conversion to fused bicyclic pyridines for all substrates reported with shorter reaction time. This method has been successfully applied to the synthesis of both fused lactones and lactams.     

Microfluidic adhesion analysis of single glioma cells for evaluating the effect of drugs

Cancer metastasis is one of the most serious problems for tumor therapy, which is closely related to cell adhesion and deadhesion process. Better comprehension of cell adhesion ability will benefit drug research. Here, a biomimetic microfluidic enzyme digestion method was proposed to gently measure the influence of drugs on cell-matrix adhesion ability at the single cell level.The method can selectively digest the extracellular matrix(ECM) that linked to a single cell, and the trypsin concentration around the cell is relatively uniform and constant, thus the measured cell adhesion strength should be precise. Commercially available anti-cancer agents including 5-fluorouracil(5-FU), actinomycin D(Act D), temozolomide(TMZ) and allicin were evaluated, and the data showed only TMZ and allicin can inhibit cell adhesion significantly under our experiment conditions. The influence of TMZ became more and more obvious as the increase of duration and the effect became prominent only after 6 h adhesion process, which could provide a quick evaluation of whether the drugs are effective to cancer cell(compared with Calcein-AM/PI cell viability test). The adhesion strength of U87 cells decreased when the concentration of TMZ increased, and the effect of TMZ can be effectively inhibited by adding lactic acid to culture medium, which indicated acidic tumor microenvironment could promote drug resistance of tumor cells. Different from conventional evaluation methods which focus on the drugs' influence on cellular viability or metabolism, this work provides a new perspective to study the effect of drugs, which is helpful to enrich the drug evaluation system.     

Preparation of [5,6]- and [6,6]-oxahomofullerene derivatives and their interconversion by Lewis acid assisted reactions of fullerene mixed peroxides

[60]Fullerene mixed peroxides C60(O)(OOtBu)4 exhibit chemo- and regioselective reactions under mild conditions. The epoxy moiety is opened by ferric chloride to form vicinal hydroxy chloride C60Cl(OH)(OOtBu)4. BF3 is also effective in opening the epoxy moiety. The O-O bond of the fullerene mixed peroxide is cleaved by aluminum chloride to form both [5,6]- and [6,6]-fullerene hemiketals (oxohomo[60]fullerenes). A Hock-type rearrangement is proposed for the formation of the hemiketals, in which a fullerene C-C bond is cleaved. Lewis acids and/or visible light can initiate isomerization of the hemiketal isomers. Single-crystal X-ray analysis and theoretical calculations confirmed the results.     

聚1-氨基蒽醌在二次锂电池正极材料中的应用

采用化学方法合成聚1-氨基蒽醌并用于二次锂电池正极材料,通过红外光谱、扫描电镜、粒度测试、循环伏安以及充放电测试等方法对材料的官能团结构、微观形貌、颗粒大小以及电化学性能等进行了研究与分析.实验表明,与金属锂组成二次锂电池后,聚1-氨基蒽醌达到了218.3 mAh•g－1的首次放电容量,经过25次循环后仍可保持较高的充放电效率.由于材料具有较高的能量密度且不含对环境有污染的元素S,因此是二次锂电池非常有希望的正极材料.