络合型催化剂丙烯聚合动力学研究

本工作对络合型(Solvay型)TiCl_3催化剂—(C_2H_5)_2AlCl体系丙烯聚合进行了活性中心浓度C_p、链增长速率常数k_p和链增长活化能E_p等的测定,并与常规TiCl_3·0.33AlCl_3进行了比较,C_p以动力学方法求取,数均分子量以粘度法测定经分子量分布校正,结果表明,络合型催化剂活性比常规催化剂高,不仅是由于C_p增高,在更大程度上是由于k_p提高。     

Toward the most versatile fluorophore: Direct functionalization of BODIPY dyes via regioselective C—H bond activation

BODIPY dyes are privileged fluorophores that are now widely used in highly diverse research fields. An overview of BODIPY dyes and a summarization of the different synthetic methodologies reported for direct C-H functionalization of the BODIPY framework have been provided.     

果蔬中L—抗坏血酸的示波计时电位K3Fe（CN）6滴定法研究

本文报导的方法是在南京大学高鸿教授研究的K_3Fe(CN)_6示波极谱滴定法(在PH8的K_2HPO_4—KH_2PO_4—KBr底液中,用0.04660mol/LK_3Fe(CN)_6标准溶液对纯抗坏血酸测定)的基础上,考虑到L—抗坏血酸(以下简称V_e)在碱性、中性介质中稳定性差,如用于V_e含量很微的果蔬测定,对结果影响大。本文改为H_2C_2O_4—KBr的酸性介质作底液,用     

Rapid and sensitive spectrofluorimetric determination of trace amounts of Hg(II) with o-vanillin-8-aminoquinoline

The fluorimetric determination of mercury ions with o-vanillin-8-aminoquinoline (OVAQ) in aqueous solutions was investigated. Hg(II) could react with the fluorescent reagent OVAQ (λ_ex/em = 278/314 nm) to form a nonfluorescent complex in an ethanol-water medium of pH 6.00. The linear range of the proposed method was from 2.5 to 80 μg/L, and the detection limit was 0.80 μg/L. The interferences of 24 foreign ions were also studied. The method was successfully applied to the determination of Hg(II) in sludge. The text was submitted by the authors in English.     

First-order mean spherical approximation for inhomogeneous fluids

The first-order mean-spherical approximation (FMSA) [Y. Tang, J. Chem. Phys., 118, 4140 (2003)] is extended to the studies of inhomogeneous fluids by combining with Rosenfeld's perturbative method [Y. Rosenfeld, J. Chem. Phys. 98, 8126 (1993)]. In the extension, the key input-direct correlation function of FMSA-is applied to constructing the free energy density functional. Preserving its high fidelity at the bulk limit, the FMSA shows satisfactory performance for Yukawa fluids near hard and attractive walls. The results are better than or comparable to several other theories reported before for the geometry. The FMSA is found, in particular, more satisfactory than the traditional mean-field theory for predicting density profiles around hard walls. The FMSA is also compared with the full MSA for inhomogeneous fluids, showing no appreciable differences. The inhomogeneous FMSA goes successfully through the self-consistency test for reproducing the radial distribution function of the bulk Yukawa fluid. As far as the computation is concerned, the FMSA can be executed much faster than any nonmean-field theories, and the speed is virtually identical to that of the mean-field theory.     

Capillary Electrophoresis of the Active Ingredients of Dioscorea bulbifera L. and its Medicinal Preparations

A method based on capillary electrophoresis with electrochemical detection has been developed for the separation and determination of epicatechin, isovanillic acid, vanillic acid and myricetin in Dioscorea bulbifera L. and its medicinal preparations. The effects of working electrode potential, pH and concentration of running buffer, separation voltage and injection time were investigated. Under optimum conditions, the analytes could be separated in a 40 mmol L^?1 borate buffer (pH 8.7) within 15 min. A 300 μm diameter carbon disk electrode has a good response at + 0.95 V (vs. SCE) for all analytes. The response was linear over three orders of magnitude with detection limits (S/N = 3) ranging from 3.0 × 10^?8 g mL^?1 to 1.0 × 10^?7 g mL^?1. The method has been successfully applied to the analysis of real samples.     

Quantum scattering calculation of the O(1D)+HBr reaction

Three-dimensional time-dependent quantum wave packet calculation for the O((1)D)+HBr reaction has been carried out using an accurate ab initio global potential energy surface [K. A. Peterson, J. Chem. Phys. 113, 4598 (2000)]. The calculations show that the initial state-selected reaction probabilities are dominated by resonance structures, and the lifetime of the resonance is generally in the subpicosecond time scale. The energy dependence of the reaction cross section is computed, which manifests still resonance structures, and is a decreasing function of the translational energy. The thermal rate constants are also computed, which are nearly independent on the temperature. The calculation results are discussed and compared to similar reaction with deep well.     

Determination of trace rhodium by supramolecular catalytic kinetic spectrofluorimetry of β-CD-rhodium-KBrO3-vanillin salicylhydrazone

A sensitive catalytic kinetic spectrofluorimetric approach for determining ng mL⁻¹ levels of rhodium is presented, and the possible mechanism of the catalytic reaction was investigated. The determination is based on the catalytic property of rhodium to enhance the reaction of o-vanillin salicylhydrazone (OVSH) with potassium bromate in a water-ethanol medium at pH 4.80 and 45 °C. The presence of β-cyclodextrin (β-CD) obviously sensitized the assay due to its high inclusion ability towards OVSH. Under optimized experimental conditions, fluorescence measurements of the β-CD-rhodium-KBrO₃-OVSH catalytic kinetic reaction system were carried out in its fluorescent band centered at λ_ex = 333 nm and λ_em = 476 nm, respectively. The calibration graph was linear over the concentration range of 0.47–100 ng mL⁻¹ with a detection limit of 0.14 ng mL⁻¹. The effect of interferences was discussed, and the results show that the extraction method can be used to separate rhodium from interference species such as iridium. The proposed method, applied to several synthetic mixtures containing rhodium mixed with varying amounts of metal salts, produced satisfactory results.     

高效液相色谱法测定糙米粉中的维生素

高效液相色谱法测定糙米粉中的维生素吴红京，唐根源，王勇（中国科学院福建物质结构研究所福州３５０００２）（福建药品检验所福州３５０００１）１前言众所周知，糙米粉有很高的营养价值，含有人体必需的多种维生素。用高效液相色谱法（ＨＰＬＣ）和薄层色谱法（ＴＬＣ...