纳米晶PbTiO3负载CuO催化NO分解

A large specific surface area perovskite-type mixed oxide PbTiO₃ supported cupric oxide was synthesized as a catalyst for NO decomposition and characterized by techniques such as XPS, XRD, H₂-TPR before and after NO decomposition reactions. The catalytic properties were tested with a fix-bed micro-reactor. The results showed that the PbTiO₃ was inactive for the reactions, but 1wt % Cu/PbTiO₃ catalyst gave fairly good activities for NO decomposition at temperature as low as 473 K. Copper species were found well-dispersed but weakly interacted with the support before NO decomposition, and the NO decomposition caused significant change in the environment of the copper species, which became Cu(Ⅰ) and most probably incorporated into surface crystal lattice of the nano-sized PbTiO₃. In NO reaction, a large amount of oxygen atoms from the decomposition of NO penetrated into the nano-sized PbTiO₃ support and caused small expansion of crystal lattice. The transport of oxygen between the copper species and the catalyst support may be helpful to speed up the kinetic regeneration of active metal sites from oxygen occupancy and resulted in good catalytic performance.     

4D-QSAR analysis of a series of antifungal p450 inhibitors and 3D-pharmacophore comparisons as a function of alignment

A training set of 55 antifungal p450 analogue inhibitors was used to construct receptor-independent four-dimensional quantitative structure-activity relationship (RI 4D-QSAR) models. Ten different alignments were used to build the models, and one alignment yields a significantly better model than the other alignments. Two different methodologies were used to measure the similarity of the best 4D-QSAR models of each alignment. One method compares the residual of fit between pairs of models using the cross-correlation coefficient of their residuals of fit as a similarity measure. The other method compares the spatial distributions of the IPE types (3D-pharmacophores) of pairs of 4D-QSAR models from different alignments. Optimum models from several different alignments have nearly the same correlation coefficients, r(2), and cross-validation correlation coefficients, xv-r(2), yet the 3D-pharmacophores of these models are very different from one another. The highest 3D-pharmacophore similarity correlation coefficient between any pair of 4D-QSAR models from the 10 alignments considered is only 0.216. However, the best 4D-QSAR models of each alignment do contain some proximate common pharmacorphore sites. A test set of 10 compounds was used to validate the predictivity of the best 4D-QSAR models of each alignment. The "best" model from the 10 alignments has the highest predictivity. The inferred active sites mapped out by the 4D-QSAR models suggest that hydrogen bond interactions are not prevalent when this class of P450 analogue inhibitors binds to the receptor active site. This feature of the 4D-QSAR models is in agreement with the crystal structure results that indicate no ligand-receptor hydrogen bonds are formed.     

A Tail Measure With Variable Risk Tolerance: Application in Dynamic Portfolio Insurance Strategy

Methodology and Computing in Applied Probability - Risk measures for tail risk have an important application in the dynamic portfolio insurance strategies. We propose a new risk measure called...     

Characterization of charge neutralization reaction in aqueous solution using the membrane separation method

Colloid titration and streaming current detector are two popular techniques used to determine the charge density of dissolved and colloidally dispersed polyelectrolytes. However, both techniques are based on some assumptions that may not be valid under some circumstances. In this paper, a membrane separation technique developed to determine the charge density and characterize a charge neutralization reaction is described. The technique characterizes the reaction between cationic and anionic charge carriers by measuring the counterions released during reaction or the unreacted small molecule charge carriers. Membranes with selected cutoff pore size were used to separate the species of interest from the bulk of the reaction mixture. Three different charge determination techniques were also compared.     

信息型常见毒物质谱用户库的建立及其在毒物快速筛选上的应用研究

质谱定性是目前世界上最通用的定性分析方法之一,在法庭科学领域毒物分析实践中,质谱一直是对未知样品进行药毒物筛选检测的利器.     

高分子填料在生物法处理废水中的应用进展

对生物法处理废水用的高分子填料进行了综述。首先,从无机高分子填料、有机高分子填料两方面介绍了其应用特点及对废水中有机物的作用机理和去除效果;其次,介绍了新型生物填料,主要从生物亲和亲水磁性填料和酶促生物填料两方面介绍其在废水处理中的应用。     

IDENTIFICATION OF LANOSTANES AND THEIR POSSIBLY GEOCHEMICAL SIGNIFICANCE IN BIYANG DEPRESSION

In the study, a series of C_(30)-C_(32) lanostane homologs have been identified from Eogene source rocks and crude oils of Biyang depression in Henan Province, China. Based upon the geochemical investigations and simulating experiments, the idea that the generation of lanostane may mainly be related to the specific original organic inputs and low maturity has been proposed.     

ALLOSTERIC REGULATION OF THE STATE OF ADENYLYLATION OF GLUTAMINE SYNTHETASE IN PERMEABILIZED CELL PREPARATIONS OF Rhoaopseudomonas sphaeroides

Following a freeze-thaw cycle, and the treatment of Rhodopseudomonas sphaeroides withthe nonionic detergent Lubrol PX, the permeabilized cell suspensions can be assayed directlyboth for the intracellular levels of glutamine synthetase and the state of adenylylation(i.e. the average number n of adenylylated subunits/dodecameric molecules). It seems that all components of the bicycle system are retained if cells grown with lowconcentrations of a?monia as the sole nitrogen source are used. The value of n was depend-ent upon the concentration of substrates (ATP, Pi) and allosteric effectors (ATP, gluta-mine and α-ketoglutarate) of adenylyltransferase. The value of n affected by UTP, thespecific substrate of the uridylyltransferase shows first the evidence that the bicycle cascadecontrol system studied in Escherichia coli may exist in this phototrophic bacterium.     

cotpp-pt/c作直接甲醇燃料电池阴极催化剂

四苯基钴卟啉;pt催化剂;直接甲醇燃料电池;氧还原     

有机溶剂中(R)-醇腈酶催化不对称合成(R)-苯乙醇腈

 研究了来源于杏仁的（R）－醇腈酶在有机溶剂异丙醚中催化苯甲醛与HCN不对称合成（R）－苯乙醇腈，初步探讨了来源于不同杏仁的（R）－醇腈酶的筛选、最适酶量的确定以及底物HCN与苯甲醛的配比、底物浓度、酶的微环境pH和反应温度对不对称合成反应的影响．结果发现，来源于苦杏仁的（R）－醇腈酶优于来源于甜杏仁的（R）－醇腈酶．优化的反应条件为：最适酶量150g／L，HCN与苯甲醛的配比2．5，苯甲醛浓度300mmol／L，酶的微环境pH5．4，反应温度0～5℃．在该优化反应条件下，反应平衡转化率和产物的光学纯度均高达99％以上．