熔融制样-X射线荧光测定钨钼锡矿中的主次成分

采用熔融制样-X射线荧光光谱法测定矿物中的Cu、Pb、Zn、Mo、W、Al、Fe、Si、K、Na、Ti、Ca、Sn等13种主次量元素,采用混合均匀的三混熔剂,以硝酸锂为氧化剂、溴化锂为脱膜剂,进行实验条件优化选择。在650℃下对样品进行预氧化,在1100℃下高温熔融,熔融时间为300 s,最后制成均匀透明,表面光滑无气孔的熔片,以部分国家一级标准物质和自制的钨钼锡标准样品,熔融制片进行测定,线性拟合建立标准曲线,并通过测定谱线选择、基体校正,使钨钼锡的测定范围扩宽,从微量到主量均能进行测定,并且适用于多种不同矿石的测定。样品的组成和含量变化会对分析线强度造成吸收、增强以及谱线重叠的影响,采用经验系数和理论α系数结合来校正其产生的基体效应。相同条件下熔融10个标准样品进行测定,其相对标准偏差(RSD)均小于5%,表明方法的准确度、精密度均满足国家相关质量标准的要求。选用一些含量不同的标准样品进行测定,最终的测定结果与标准值相符,表明方法可用于钨钼锡矿的测定。     

128例脑性瘫痪血钙、锌、铁、铜、镁元素分析

为探讨小儿脑性瘫痪(CP)体内微量元素的变化,测定了128例脑性瘫痪患者血钙、锌、铁、铜、镁含量,随机选择128例正常儿童进行对照分析。结果表明,两组病例血锌、铜、镁均在正常范围,脑瘫组血钙56例、铁45例低于正常参考值,健康组血钙16例、铁11例低于正常参考值。经统计学处理,两组病例中血钙、铁、铜、镁含量具有显著性差异(P<0.05),血锌无显著性差异(P>0.05)。提示脑瘫儿童血钙、铁、铜、镁含量均低于正常儿童,补充钙、铁、镁等可能有利于脑瘫康复。     

中药质量控制技术发展展望

本文从中药产业需求、现代化需求、技术需求、机遇与挑战等方面概括了中药质量控制技术发展的背景;讨论了中药质量控制技术对于提高中药药效和安全性、推动产业发展和推进中药国际化的意义;综述了中药质量控制技术的现状,分析了在过程控制、安全性控制、标准品和对照品制备、指纹图谱技术等方面的不足;提出了中药质量控制技术应重点发展以分离和表征技术为主的中药质量控制关键技术、中药安全性控制技术、中药质量控制标准体系、中药质量控制原创性技术和中药标准品、对照品生产技术,制定技术标准,建立具有中药特色的过程控制和产品质量控制标准。     

血清铁、锌、钙、镁、磷与妊娠的关系探讨

为探讨血清铁、锌、钙、镁、磷在孕妇体内的水平，做好围产期孕妇的保健工作，提高孕产妇的健康水平和新生儿健康素质，抽取125例孕中期妇女空腹静脉血，采用透射比浊法测定了其血清铁、锌、钙、镁、磷的含量。结果表明，铁、锌、钙、镁、磷的异常在孕妇中有一定的发生率，其中尤以钙与锌的缺乏最为多见。提示应定期检测孕妇血清铁、锌、钙、镁、磷水平，并采取相府的防治措施．以提高孕产妇及新生儿的健康水平。     

Cathode of a hydrogen-oxygen fuel cell with a solid polymer electrolyte: The effect of the flooding of pores by water on the characteristics of the active layer

A computer model of the active layer of the cathode of a hydrogen-oxygen fuel cell with a solid polymer electrolyte is studied. The active mass of the electrode consists of equidimensional grains of the substrate (agglomerates of carbon particles with platinum particles embedded in them) and a solid polymer electrolyte (Nafion). The flooding by water can be experienced by both the pores in the substrate grains, which facilitate the oxygen penetration into the active layer of the electrode, and the voids between the grains. All possible versions of the flooding of these pores by water are considered. A calculation of the optimum, at a given polarization of the electrode, value of electrochemical activity, the thickness of the active layer, and the weight of platinum is performed. The major parameters of the system are the concentrations of grains of the substrate and solid polymer electrolyte, the size of these grains, the platinum concentration in the substrate grains, the average diameter of pores in the substrate grains, and the polarization of electrodes. The ultimate aim of the work is to estimate how the flooding of pores of the active layer of the cathode by water affects the magnitude of the optimum current, the effective thickness of the active layer, and the weight of platinum.Translated from Elektrokhimiya, Vol. 41, No. 1, 2005, pp. 35–47.Original Russian Text Copyright © 2005 by Chirkov, Rostokin.     

Metal chelates of phosphonate-containing ligands: VII. Analytical applications of 1-hydroxyethane-1,1-diphosphonic acid

The polarographic behavior of copper, lead, antimony, and zinc ions in the presence of the title ligand, HEDP, is discussed. In highly alkaline solutions, the reversible wave of copper splits into two components, reversible and irreversible, the first of which is attributed to the reduction of the free cupric ions and the second wave was assigned to the reduction of the copper phosphonate species. The polarograms of zinc and antimony showed the presence of a single irreversible wave. In the case of lead, a quasi-reversible wave is observed. Cobalt and nickel forms inactive phosphonate chelates as inferred from the suppression of the wave heights with increasing of both the concentration of the ligand and the pH of the medium. In the presence of sufficiently excess HEDP buffered to pH 11.8, mixtures of the six elements showed the presence of four reasonably separated waves at half-wave potential values ?0.51, ?0.83, ?1.17, and ?1.55 V vs SCE corresponding to the reductions of copper, lead, antimony, and zinc complexes, respectively. The possibility of the individual and simultaneous analysis of these elements in their ternary mixtures with cobalt and nickel is discussed.     

Preparation of high-quality colloidal mask for nanosphere lithography by a combination of air/water interface self-assembly and solvent vapor annealing

Nanosphere lithography (NSL) has been regarded as an inexpensive, inherently parallel, high-throughput, materials-general approach to the fabrication of nanoparticle arrays. However, the order of the resulting nanoparticle array is essentially dependent on the quality of the colloidal monolayer mask. Furthermore, the lateral feature size of the nanoparticles created using NSL is coupled with the diameter of the colloidal spheres, which makes it inconvenient for studying the size-dependent properties of nanoparticles. In this work, we demonstrate a facile approach to the fabrication of a large-area, transferrable, high-quality latex colloidal mask for nanosphere lithography. The approach is based on a combination of the air/water interface self-assembly method and the solvent-vapor-annealing technique. It enables the fabrication of colloidal masks with a higher crystalline integrity compared to those produced by other strategies. By manipulating the diameter of the colloidal spheres and precisely tuning the solvent-vapor-annealing process, flexible control of the size, shape, and spacing of the interstice in a colloidal mask can be realized, which may facilitate the broad use of NSL in studying the size-, shape-, and period-dependent optical, magnetic, electronic, and catalytic properties of nanomaterials.     

微波消解－ICP-OES测定钛渣中常量或微量杂质

钛渣样品采取高压密闭微波加热方式以HF、HNO3进行消解,采用电感耦合等离子体原子发射光谱法(ICP-OES)直接同时测定常量、微量杂质铁、铅、砷、铬、铜、磷、锰、钒、镁、钙。考察了消解条件、基体钛以及共存元素之间的干扰影响、等离子体参数等测定条件,通过优选元素分析谱线、以及采用基体匹配与同步背景校正相结合的方式消除光谱干扰和基体效应。测定50、60、70、80、90等不同品位钛渣中杂质元素的结果表明:方法检测范围涵盖了0.005%～10.0%的钙、镁、铁,以及0.005%～2.0%的铅、砷、铬、铜、磷、锰、钒,校准曲线相关系数大于0.999 2;背景等效浓度0.002%～0.0015%,检测限0.0009～0.0038%;含量不小于1.0%的RSD低于0.677%,在0.010%～0.10%含量范围内RSD低于3.85%;回收率为90.0%～108.0%。以本法对70、80、90 3个高钛渣标准样品的定值分析结果与传统化学方法对照一致。     

表面单层组装多环芳烃荧光行为的Monte Carlo模拟

Recently,a series of sensing films based upon the supra-molecular behavior of aromatic compounds immobilized on substrate surfaces and its dependence to the composition of the medium have been successfully prepared. It is found that the properties and performances of the films depend upon various factors,including the nature of the sensing element,the way of immobilization,the nature of the substrate,and the density of the sensing element immobilized etc. To accelerate and deepen the studies,it was decided to carry out the theoretical simulation of the sensing films based upon the proposed principle. The fluorescence behavior of a functional plate,of which the surface is functionalized by single layer immobilization of aromatic compounds（sensing elements）,is simulated by Monte Carlo simulation method. The effects of the immobilization density of a sensing element,the excitation efficiency,and the association efficiency,P,which is a characteristic parameter of an aromatic compound,between the molecules of the sensing element on the ratio of the excimer emission to the monomer emission of the plate have been systematically examined. But the effects of the length and flexibility of a spacer are neglected,because in this simulation aromatic compounds are immobilized on a plate by the short stiff spacer. It is demonstrated that,for a functionalized plate of a short stiff spacer in a polar solvent（ in this case,the association tendency is strong,and P is close to 1）,aromatic compounds of middle excitation efficiency might be suitable as sensing elements. In addition,the immobilization density of the sensing element should be controlled. A recommended value is about 50%.     

Lipopolysaccharides of the pseudotuberculosis microbe Yersinia pseudotuberculosis

This review generalizes the results of structural investigations of the polysaccharides of the O-specific side chains, of the core oligosaccharides, and of the lipid A of the pseudotuberculosis microbeYersinia pseudotuberculosis which causes Far-Eastern scarlatina-like fever. The complete structures of the repeating units of the specific polysaccharides from the lipopolysaccharides of serovars I A, I B, III, IV A, V A, V B, and VI which are responsible for the O-antigenic specificity of the microorganism are given. For the majority of serovars the repeating unit is represented by a branched pentasaccharide. Exceptions are the lipopolysaccharides of serovars I A and III which have a tetrasaccharide repeating unit. The presence of an aminosugar residue at the reducing end, by which the O-specific chain is attached to the oligosaccharide of the core, is common and characteristic for the lipopolysaccharides isolated from all the serovars. The structures of the core oligosaccharide and of lipid A, which are common for all serovars ofYersinia pseudotuberculosis, are given.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, USSR Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 163–171, March–April, 1988.     

High-performance liquid chromatography of alkaloids

Literature information on the HPLC of alkaloids, including adsorption, reversed-phase, ion-exchange, ion-pair, and other variants is generalized. Results are given of the chromatographic analysis of various classes of alkaloids with an indication of the conditions of separation, and the columns used, and also of the methods of detection. The advantages and disadvantages of the HPLC variants are discussed. The review includes the literature over the last 14 years. Scientific Center for Chromatography, Institute of Chemistry and Physics of Polymers, Uzbek Academy of Sciences, Tashkent. Institute of the Chemistry of Plant Substances, Uzbek Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 595–613, September–October, 1991.     

Electrophoresis of a concentrated aqueous dispersion of non-Newtonian drops

The electrophoresis of a concentrated dispersion of non-Newtonian drops in an aqueous medium, which has not been investigated theoretically in the literature, is analyzed under conditions of low zeta potential and weak applied electric field. The results obtained provide a theoretical basis for the characterization of the nature of an emulsion and a microemulsion system. A Carreau fluid, which has wide applications in practice, is chosen for the non-Newtonian drops, and the unit cell model of Kuwabara is adopted to simulate a dispersion. The effects of the key parameters of a dispersion, including its concentration, the shear-thinning nature of the drop fluid, and the thickness of the double layer, on the electrophoretic behavior of a drop are discussed. In general, the more significant the shear-thinning nature of the drop fluid is, the larger the mobility is, and this effect is pronounced as the thickness of the double layer decreases. However, if the double layer is sufficiently thick, this effect becomes negligible. In general, the higher the concentration of drops is, the smaller the mobility is; however, if the double layer is either sufficiently thin or sufficiently thick, this effect becomes unimportant.     

Theoretical ONIOM2 study on pyridine adsorption in the channels and intersection of ZSM-5

The structures of the acid sites in the channels and intersections of H-, Li-, and Na-ZSM-5 (ZSM = zeolite socony mobil) and their interactions with pyridine molecule have been computed by using three corresponding models containing 22 tetrahedral sites. The calculated adsorption energies of pyridine in the intersection regions of H-, Li-, and Na-ZSM-5 are 197.0, 172.5, and 122.3 kJ/mol, respectively, in good agreement with the respective experimental values of 200 +/- 5, 155-195, and 120 kJ/mol, while those in the straight and sinusoidal channels are much smaller (157.9 and 127.6, 152.2 and 149.4, and 150.4 and 109.9 kJ/mol, respectively). These indicate that the most probable adsorption site for pyridine in ZSM-5 is the acidic site located in the intersection region. The structural parameters of the adsorption complexes show that the acidic proton in the three models of H-ZSM-5 has been transferred to the nitrogen of pyridine, while in alkali cation-exchanged ZSM-5, the coordination of the alkali cation to the nitrogen atom of pyridine dominates the overall interaction. In addition, the adsorption complexes were further stabilized by the long-range electrostatic interaction between the positively charged pyridine hydrogen atoms and the negatively charged lattice oxygen atoms of the zeolite framework. In the intersection regions of H-, Li-, and Na-ZSM-5, the coordination energy of the charge-compensating cation to the pyridine nitrogen amounts to 58, 60, and 68% of the total adsorption energy, respectively, while another 42, 40, and 32%, respectively, is due to long-range electrostatic interactions. This indicates that the zeolite lattice framework surrounding the adsorption site has important contributions to the adsorption energy of the pyridine molecule.     

On the mechanism of the formation of ozonides of the alkali metals

Conclusions A mechanism of the formation of ozonides of alkali metals was proposed on the basis of data obtained in an investigation of the reaction of oxygen-labeled KOH with ozone, the reaction of KOH with atomic oxygen, and the reaction of KOH with ozone; this mechanism is based upon: the catalytic decomposition of ozone on the surface of the solid alkalies into molecular and atomic oxygen, the interaction of the latter with the hydroxide, forming a superperoxide, and an interaction of the superperoxide with ozone, forming the ozonide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1183–1187, June, 1967.     

Mechanisms of foam destruction by oil-based antifoams

Oils and mixtures of oils with hydrophobic particles are widely used in various technologies and consumer products to control foaminess and foam stability. The aim of this review is to summarize our current understanding of the mechanisms of foam destruction by such substances, which are usually called antifoams or defoamers. The experimental results show that two types of antifoam can be distinguished (called for brevity "fast" and "slow") which differ in the modes of their action. Fast antifoams are able to rupture the foam films at the early stages of film thinning. As a result, fast antifoams destroy completely the foam in less than a minute, in a typical foam-stability test. Microscopic observations have shown that the fast antifoams rupture the foam films by the so-called "bridging" mechanisms, which involve the formation of oil bridges between the two surfaces of the foam film. The stability/instability of these oil bridges is explained by using the theory of capillarity. In contrast, the oily globules of the slow antifoams are unable to enter the surfaces of the foam films and are first expelled into the Plateau borders (PBs). Only after being compressed by the narrowing walls of the PBs (due to water drainage from the foam), are the globules of the slow antifoams able to enter the solution surface and to destroy the adjacent foam films. Typically, the process of foam destruction by slow antifoams requires much longer time, minutes or tens of minutes, and a residual foam of well-defined height is observed in the foam tests. The experiments show that there is no direct relation between the magnitudes of the entry, E, spreading, S, and bridging, B, coefficients, on one side, and the antifoam efficiency, on the other side. The only requirement for having active antifoam, with respect to the bridging mechanisms, is that B should be positive. On the other hand, the barrier preventing the emergence of pre-emulsified antifoam globules on the solution surface (so-called "entry barrier") is of crucial importance for the mode of foam destruction and for the antifoam efficiency. Measurements of the entry barrier with recently developed film trapping technique (FTT) showed that antifoams possessing low entry barriers act as fast antifoams, whereas high barriers correspond to slow or inactive antifoams, although E, S, and B coefficients could be strongly positive in the latter case. A good agreement between the magnitude of the entry barrier, measured by FTT, and the height of the residual foam, in the presence of slow antifoams, was experimentally established and theoretically explained. The importance of various factors, such as the size of antifoam globules, oil spreading, kinetics of surfactant adsorption, hydrophobicity of solid particles in mixed oil-solid antifoams, and the presence of amphiphilic additives (foam boosters), is discussed from the viewpoint of the mechanisms of antifoaming. The main experimental methods, used for studying the modes of antifoam action, are briefly described.     

Determination of heavy metals in the Rock River (Illinois) through the analysis of sediments

Neutron activation analysis has been used to analyze sediment cores from the Rock River and two branches of Kent Creek, one of its tributaries, to determine the concentrations of thirteen heavy metals (Ti, Cu, V, Mn, As, Sb, Se, Cr, Ni, Sc, Fe, Zn, and Co) and two rare earths (Sm and La). The downstream sites of both the Rock River and the two branches of Kent Creek have elevated concentrations of several heavy metals including arsenic, antimony, and zinc. In addition, hundreds of parts per million of copper have been found in samples from the downstream site of the North Fork of Kent Creek. Toxicity tests of the sediment also indicate that the downstream sites are detrimental to lifeforms. Analysis of the data from the two branches of Kent Creek clearly indicate that heavy metal concentrations increase as the distance from the center of industrial activity (Rockford) decreases.     

电解液添加成份对贮氢电极性能影响的初步研究

电解液添加成份对贮氢电极性能影响的初步研究蔡称心，黄翠虹（南京大学化学系，南京，２１０００８）王宝忱（中国科学院长春应用化学研究所，长春１３００２２）关键词：贮氢电极，ＭＨ／Ｎｉ电池，添加剂自从Ｊｕｓｔｉ和Ｅｗｅ￣［１，２］发现贮氢合金能够用电化学方...     

金属离子在生命过程中的作用机制

生命活动是一系列错综复杂的生物反应,包含着元素的获取、作用、代谢等生理过程。文章重点从机体组织构成、生长发育、能量和物质的新陈代谢、生物和神经信号的传递等不同生命活动中金属离子所起的作用及其作用机制进行了综述。结果表明金属离子在许多生命活动中起到了至关重要的作用。文章为生物元素调节、金属药物研制和疾病防治等应用提供了一定的理论基础。     

Numerical simulation of the tensile modulus of nanoclay-filled polymer composites

A numerical simulation model that incorporates three phases, polymer matrix, interlayer, and clay platelet, was developed to predict the tensile modulus of nanoclay-filled polymer composites. The interlayer was introduced to account for the fact that the mechanical properties of the polymer near the clay surface are different from those of the polymer matrix. The effects of the properties of interlayers, the structure of clay clusters, and platelet distributions upon the modulus of elasticity of the nanocomposites, were studied. The simulation results show that a decrease in the interlayer modulus, as well as an increase in the interlayer thickness, would decrease the modulus of the nanocomposites. Furthermore, it was found that the maximum strain, located in the interlayer near the end of the clay platelet, increases significantly with decreasing interlayer modulus. The effects of the distribution of clay platelets upon composite modulus were interpreted in terms of two parameters, platelet overlap length, and the lateral distance between platelets. Comparison of simulation results with experimental data from the literature has confirmed the reliability of the numerical simulation method used in the present study. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2391–2406, 2004