Selective dimerization of α-methylstyrene catalyzed by a solid acid

A novel solid acid prepared from concentrated sulfuric, boric and phosphoric acid is a highly selective catalyst for the dimerization of α-methylstyrene at room temperature to generate 4-methyl-2,4-diphenyl-1-pentene.     

Influences of the Hydrophobicity of the Heme-binding Pocket on the Properties and Functions of Cytochrome b_5 Mutants

IntroductionElectrontransferreactionsarethekeystepsinphoto synthesis ,respirationandmanyotherbiochemicalprocess es.1Cytochromeb5isaredoxproteinexistingwidelyinnature ,whichactsasanelectron carrierduringvariouselectrontransferprocessesinthebiologicalsystem .2Cytochromeb5isamembraneproteinwithmolecularweightofapproximately 16kDa ,ofwhichthehydrophobicC terminaldomainanchorscytochromeb5tothemem brane ,andthehydrophilicN terminaldomaincontainshemeprostheticgroupandexhibitsthebiologicalfunctionsof…     

Studies on the Spectral Behavior between Protein with Poniacyl Carmine 2B and its Analytical Application

In this paper, the spectral behavior of protein and Poniacyl Carmine 2B (PC 2B) has been studied by spectrophotometric method. The conditional constants, apparent combination constant K and maximum binding number n, were used to express the combination ability of the reactions between PC 2B and protein under a set of given conditions. The Sandell index s was used to express the sensitivity of the determination of protein. The factors, acidity, PC 2B concentration and the ionic strength, were discussed by the change of apparent combination constant and maximum binding number. It was found that acidity of the solution, PC 2B concentration and ionic strength had a significant effect on the sensitivity of the assay of protein. Under the optimal conditions, the apparent combination constant K and the maximum binding number n were 2.36 × 10⁶ L mol^?1 and 95, respectively. With further investigation, it was found that the Scatchard model was suitable in treating the data obtained in the experiments. In the buffer medium of HCl‐KCl at 1.87, the addition of protein made the maximum absorption of the system move from 527 nm to 513 nm. Its apparent molar absorptivity is 4.46 × 10⁵ Lmol^?1 cm^?1 at 513 nm. Beer's law is obeyed in the range of 0 ? 55 μg mL^?1. The system developed in this paper has been used for the determination of protein in milk powder successfully.     

Ru/Mn-Ce/TiO2催化剂催化湿式氧化丁二酸的反应活性和动力学研究

在二氧化钛载体中通过掺杂Ru，Mn，Ce制备了一系列用于催化湿式氧化的催化剂，利用XRD，TEM，BET等手段对催化剂进行了表征．在反应温度T=210～270℃，氧分压Po2=2．1MPa条件下，在间歇式高压反应釜中对丁二酸进行了降解实验．催化剂在反应中有很高的催化活性．催化剂在30min内对丁二酸降解的COD去除率为54．4～98．3％．Ru及Mn，Ce的氧化物对催化活性都有促进作用．建立了丁二酸催化湿式氧化的一级分段动力学模型．基于COD的一段及二段反应的活化能分别为43．74kJ／mol和54．28kJ／mol．     

A vacuum ultraviolet photoionization mass spectrometric study of acetone

The photoionization and dissociative photoionization of acetone have been studied at the photon energy range of 8-20 eV. Photoionization efficiency spectra for ions CH3COCH3+, CH3+, C2H3+, C3H3+, C3H5+, CH(2-)CO+, CH3CO+, C3H4O+, and CH3COCH2+ have been measured. In addition, the energetics of the dissociative photoionization has been examined by ab initio Gaussian-3 (G3) calculations. The computational results are useful in establishing the dissociation channels near the ionization thresholds. With the help of G3 results, the dissociation channels for the formation of the fragment ions CH3CO+, CH2CO+, CH3+, C3H3+, and CH3COCH2+ have been established. The G3 results are in fair to excellent agreement with the experimental data.     

紫外分光光度法测定甲砜霉素片的含量

根据甲砜霉素的紫外吸收特征,建立了以乙腈-水为溶媒、(225±1)nm为最大吸收波长的紫外分光光度法。方法的线性范围为0.5～25.0μg/mL,平均回收率为99.92％,RSD为0.30％。用对照品比较法测定5批甲砜霉素片的含量,并与中国药典方法的测定结果进行比对,结果表明,两种方法的测定结果基本一致。     

球形SiO2-Al2O3的制备、结构和性能

将Na2SiO3·9H2O 溶液通过强酸性阳离子树脂进行离子交换得到酸性硅溶胶,再将硅溶胶与铝溶胶及六次甲基四胺混合后采用油柱成型法制备了球形SiO2-Al2O3复合氧化物. 通过XRD、BET 及TPD等手段对样品进行测试和表征, 结果表明, 600 ℃焙烧得到的SiO2-Al2O3中SiO2以无定型形式存在, 其比表面、孔容与表面酸性随SiO2含量的增加而提高, 孔径、堆密度随SiO2含量的提高而减小, 压碎强度基本保持不变.     

微铂电极上1-酰基二茂铁动力学参数的测定

本文合成并研究了１－酰基二茂铁在ＣＨ２Ｃｌ２中的伏安行为，测定了它们在ＣＨ２Ｃｌ２中不同支持电解质浓度时的扩散系数，并分明用Ｚ．Ｇａｌｕｓ和Ｋ．Ａｏｋｉ方法计算了两种状态下的电子迁移速率常数。讨论了取代基的诱导效应和共轭效应及其链长对１－酰基二茂铁的动力学性质的影响以及支持电解质及其浓度等因素对伏安曲线的影响。     

新型分子筛Ti-MMM-1的合成及其催化性能的研究

通过控制TEOS的水解，在不同时间添加与MCM-41和MFI相应的有机模板剂合成出了一种新型分子筛，Ti-MMM-1，采用XRD、FT-IR和低温N2吸附对其进行表征，并用H2O2氧化环己烷和环己醇对其催化活性进行评价．结果表明，Ti-MMM-1是一种具有MCM-41和MFI结构的两相混合的微孔／介孔材料，IR分析表明钛原子已进入分子筛骨架，并在环己烷和环己醇的氧化中表现出较好的催化活性和较高的选择性．     

SnO2-Nb2O5/MgAl2O4/α-Al2O3催化环氧乙烷水合制乙二醇

采用水热稳定的MgAl2O4尖晶石对-αAl2O3载体表面进行修饰,采用具有较强亲水性能的SnO2对活性组分Nb2O5进行修饰,制备了SnO2-Nb2O5/MgAl2O4/-αAl2O3催化剂,并用于环氧乙烷水合制乙二醇反应.采用X射线衍射、红外光谱和程序升温脱附研究了Sn/Nb摩尔比对催化剂酸性、环氧乙烷在催化剂表面的吸附状态和吸附强度以及催化剂性能的影响.结果表明,Sn/Nb摩尔比明显影响催化剂的组成和结构;催化剂的结构不同,环氧乙烷在催化剂表面的吸附强度存在明显差别,催化剂的催化性能明显不同.