聚类分析法在食品TE分级中应用研究

用１５种食品的Ｚｎ、Ｃｕ、Ｆｅ、Ｍｇ含量作分级特征，按聚类分析分级，结果以Ｚｎ、Ｃｕ、Ｆｅ、Ｍｇ总量均值最低的蕃茄为Ⅰ级；低的白鸡、鲜牛奶、黄瓜、新会柑、罗岗橙为Ⅱ级；高的精面粉、水豆腐、粉丝、牛肉、鸡蛋、鸭蛋、西洋菜、白芽为Ⅲ级；最高的红豆为Ⅳ级．提示膳食中Ｚｎ、Ｃｕ、Ｆｅ、Ｍｇ含量大于供给量标准时可选Ⅲ、Ⅳ级，小于标准选Ⅰ、Ⅱ级，＝标准选Ⅰ、Ⅲ级食品．据此认为聚类分析法可用于食品分级，对选择食品、制订食谱、营养治疗、食品科研、研制食品配方等均具有实用价值和指导意义。     

一类新的4-取代胂酸型变色酸偶氮多卤显色剂的合成及其与稀土元素显色反应的研究

本文研究了五个结构新颖的显色剂与稀土元素的显色反应。其中的二溴羧基偶氮氯肿(CAsA-DBK)与稀土元素反应具有对比度大、灵敏度高、选择性好等优点。在0.6mol/LHClO_4介质中,不加任何掩蔽剂条件下,只与铈组稀土显色,与钇组稀土几乎不显色,是一个较有特色的铈组稀土试剂。     

Electrochemical synthesis of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles in alkaline aqueous solutions containing complexing agents

Ultrafine magnetite particles are prepared through an electrochemical process, at room temperature, from an iron-based electrode immersed in an alkaline aqueous medium containing complexing compounds. XRD and chemical analysis indicate that the product is pure magnetite, Fe₃O₄. The size and morphology of the particles are studied by SEM. The magnetite nanoparticles present a magnetoresistance of almost 3%, at 300 K, under a magnetic field of 1 T. A reactive mechanism for the electrochemical process is proposed.     

The Electrochemical Behavior of Keggin Polyoxometalate Modified by Tricyclic,Aromatic Entity

The inorganic‐organic hybrid polyoxometalates (POMs), (pbpy)₄H[PMo₁₂O₄₀(VO)] ( 1 ) and (pbpy)₄H₄[SiMo₁₂O₄₀] ( 2 ) (pbpy=5‐phenyl‐2‐(4‐pyridinyl)pyridine), have been synthesized and were, respectively, used as a solid bulkmodifier to fabricate a three‐dimensional bulk‐modified carbon paste electrode (CPE) by direct mixing. The electrochemical behavior and electrocatalysis of 1 and 2 modified CPE ( 1 ‐CPE and 2 ‐CPE) have been studied in detail. Both 1 ‐CPE and 2 ‐CPE show remarkable stability that can be ascribed to the doped organic conjugated pbpy, which is very important for practical applications in electrode modification.     

Analysis of metabolites of glucose pathways in human erythrocytes by analytical isotachophoresis

A method for the quantitative determination of the major anionic constituents of fountain solutions, typically mono-, di- and hydroxycarboxylates, alkylbenzenesulfonates, and inorganic anions, including orthophosphate and polyphosphates, is presented here for the first time. The analytical problems arising from extensive co-elution of many of these analytes on an ion-exchange column have been resolved through a combination of (i) careful selection of the concentration gradient of the sodium hydroxide eluent; (ii) parallel analysis by ion-exclusion chromatography; and (iii) determination of total phosphorus by inductively coupled plasma atomic emission spectrometry.     

Influence of the texture of chromia catalysts on their activity in synthesis of 2-methylthiophene

The texture of Cr₂O₃-K₂O/Al₂O₃catalysts containing oxides of rare earth elements (REE) was studied. The catalysts are used for the synthesis of 2-methylthiophene by the reaction of H₂S with n-pentane or piperilene. The heterocyclization of n-pentane is a consecutive reaction involving a step of dehydrogenation of initial hydrocarbon. At this step the texture of the catalyst affects the yield of 2-methylthiophene. The yield of 2-methylthiophene obtained from piperilene and I₂S is independent of the catalyst texture.     

Method for the determination of thorium and uranium in urine by ICP-MS

ICP-MS (inductively coupled plasma mass spectrometry) is shown as a very sensitive method for quantitative determination of Th and U concentration and excretion analysis in urine without any sample pretreatment. The current standard method for incorporation monitoring applies alpha-spectrometry, a very tedious and time consuming technique. ICP-MS offers an attractive alternative for monitoring of thorium and uranium body burdens in occupationally exposed subjects and also larger groups of the general population. A limit of determination of 0.5 ng/L in aqueous solutions and 1 ng/L in urine samples for both elements was achieved, with a precision of about ± 10% in the concentration range of appr. 10 ng/L. Due to the lack of a suitable reference material, the accuracy of the method was tested by comparing some of the results with those obtained by -spectrometry, especially for U. There was a sufficient agreement on both results.     

On the calculation of expectation values and transition matrix elements by coupled cluster method

Summary Finite order expressions are derived for expectation values and transition matrix elements within the framework of the coupled cluster method.     

内蒙古牧区蒙、汉族人发铜、锌、铁、锶及钙的X-射线荧光光谱法测定

用X-射线荧光光谱法，测定了387例内蒙古牧区蒙古族、汉族成人和儿童的发中铜(Cu)、锌(Zn)、铁(Fe)、锶(St)及钙(Ca)的含量，对同一地区蒙、汉族成人间，成人及儿童间发中五种元素含量进行了比较分析。结果表明：蒙汉族成人发中Cu，Zn、Fe含量不受种族及饮食习惯的影响，其含量无显著性差异；蒙汉族成人发中Sr和Ca含量存在着相平行的显著差异；牧区儿童发Zn含量与牧区成人发Zn含量差异无显著性意义，提示牧区儿童不缺Zn，可能与多动物性食物有关；牧区儿童发中Cu、Fe、Sr、Ca均显著低于牧区成人、可能与儿童发育旺盛和Zn摄入量高对Cu、Fe吸收发生抑制有关。