Ternary complexes in solution. Comparison of the coordination tendency of some polybasic oxygen acids toward the binary complexes of Cu(II) andAMP,ADP orATP

Summary Potentiometric equilibrium measurements have been made at 25±0.1°C (=0.1 mol dm^–3 KNO₃) for the interaction of adenosine-5-mono-, -di- and -triphosphate (AMP,ADP andATP) and Cu(II) with biologically important secondary ligand acids (malic, maleic, succinic, tartaric, citric and oxalic acids) in a 1:1:1 ratio and the formation of various 1:1:1 mixed ligand complex species inferred from the potentiometricpH titration curves. Initial estimates of the formation constants of the resulting species and the acid dissociation constants ofAMP,ADP,ATP, and secondary ligand acid, have been refined with the SUPERQUAD computer program. In some systems logK values are positive, i.e. the ternary complexes are found to be more stable than the corresponding binary complexes. In some Cu(II) ternary systems the interligand interactions between the coordinate ligands, possibly H bond formation, have been found to be most effective in deciding the stability of the ternary complexes formed in solution. Stabilities of mixed ligand complexes increase in the orderAMP <ADP <ATP. With respect to the secondary ligands, the formation constants of the mixed ligand complexes decrease in the order succinic > maleic > tartaric > malic > citric > oxalic acid.

---

Ternäre Komplexe in Lösung. Vergleich der Koordinationstendenz einiger polybasischer Sauerstoffsäuren gegenüber binären Komplexen von Cu(II) mitAMP,ADP oderATP

Zusammenfassung Es wurden potentiometrische Gleichgewichtsmessungen bei 25±0.1°C bei =0.1 mol dm^–1 KNO₃ durchgeführt, um die Wechselwirkung von Adenosin-5-mono-, -di- und triphosphat mit Cu(II) und biologisch relevanten Sekundärliganden wie Äpfel-, Malein-, Bernstein-, Wein-, Zitronen- und Oxalsäure im Verhältnis 1:1:1 festzustellen. Aus den potentiometrischenpH-Titrationskurven ergaben sich verschiedene 1:1:1 gemischte Ligandenkomplexe. Anfänglich abgeschätzte Komplexbildungskonstanten der Komplexe und Säuredissoziationskonstanten vonAMP,ADP undATP und den Sauerstoffsäuren wurden mittels des Computerprogramms SUPERQUAD verfeinert. In einigen Systemen ist logK positiv, demzufolge sind die ternären Komplexe stabiler als die korrespondierenden binären. In einigen ternären Cu(II)-Komplexen bestehen zwischen den Liganden Wechselwirkungen, vermutlich auf der Basis von stabilitätsfördernden Wasserstoffbrückenbindungen. Die Stabilitäten der gemischten Komplexe steigen in der ReihenfolgeAMP <ADP <ATP. Bezüglich der Sekundärliganden ergibt sich für die Bildungskonstanten der ternären Komplexe die Reihung Bersteinsäure > Maleinsäure > Weinsäure > Äpfelsäure > Zitronensäure > Oxalsaure.

     

水环境中有机污染物生化需氧量的测定

本文从理论和实践上讨论了水质监测中有机污染物生化需氧量(BOD)测定中的有关问题。其中包括BOD测定中发生的生化反应过程，好氧生化反应速率及速率常数，影响BOD测定结果的各种因素，BOD测定技术，以及BOD与COD、TOC的相关性。     

Oxygen chemisorption on divalent chromium ions in chromosilicate systems

A study has been made of the chemisorption of O₂ from various gaseous media on divalent chromium ions in chromosilicate systems under dynamic conditions. After passing through the chemisorbent layer the residual O₂ content of the gaseous mixtures is 10^–6–10^–7 vol. %. The adsorption capacity of the chemisorbents increases in proportion to their Cr(II) content and decreases as the moisture content increases in the gas mixture from which the oxygen is absorbed. The chemisorbents can be repeatedly regenerated by treating them with hydrogen.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2500–2505, November, 1992.     

14C dating of ancient rock art: A new application of plasma chemistry

We have developed a new statically operated oxygen plasma method that allows direct¹⁴C dates to be obtained from ancient rock paintings. The method is applicable even to paintings on limestone (CaCO₃) walls. A sample of a pictograph which had naturally spalled offa shelter wall in the Lower Pecos region of Texas was subjected to a low temperature ( 150°C) oxygen plasma to selectively remove the organic carbon-containing material used in the paint as CO₂, without contamination from the limestone substrate. The Zürich EHT accelerator mass spectrometer was then used to determine the radiocarbon age of this prehistoric rock painting. It was successfully dated at 3865 ± 100 years BP, in good accord with the archaeological context which has set the onset of this Pecos River style of pictograph between 4100 and 3200 years BP. The method appears feasible and is applicable to rock art in which organic materials were used in the paint.     

Thermoanalytical Study of the Composition of β-tungsten

The aim of the present work was to provide arguments to the almost ‘hystorical’ problem of what β-tungsten is. WO₃was reduced in dry H₂gas atmosphere in order to examine, whether β-tungsten formed in such a way contains oxygen as part of the lattice described as W_xO (e.g. W₂₀O) or is a pure metallic phase of tungsten. As a result of thermoanalytical measurements and of chemical analysis for oxygen, the assumption is supported that in the 600-800°C temperature range of metal formation not the W_xO (β-W)→W(α-W) transformation but the β-W→α-W structural rearrangement of materials with identical chemical composition is the most probable process. The earlier opinion that the formation of the β-W structure requires the presence of oxygen atoms was not verified by our results. This revised version was published online in July 2006 with corrections to the Cover Date.     

聚苯乙烯键合麻黄碱-Co(Ⅱ)络合物对烯烃环氧化反应的催化作用

聚苯乙烯键合麻黄碱 Ｃｏ（Ⅱ）络合物对烯烃环氧化反应的催化作用刘庆艳刘必前何纪纲（中国科学院化学研究所北京１０００８０）关键词环氧化，分子氧，烯烃，醛，高分子催化剂烯烃的环氧化反应是将烯烃进行氧化转化的重要反应［１］．由于高分子催化剂具有与反应...     

Thermal analysis study of Bi<Subscript>2</Subscript>Sr<Subscript>2</Subscript>Ca<Subscript>2</Subscript>Cu<Subscript>3-x</Subscript>Er<Subscript>x</Subscript>O<Subscript>10+δ</Subscript> glass-ceramic system

Summary We have fabricated glasses in the Bi-2223 HT_c superconductor system with Bi₂Sr₂Ca₂Cu_3-xEr_xO_{10+ δ} nominal composition, where x=0.5 and 1.0, by the glass-ceramic technique. Using an analysis developed for non-isothermal crystallization studies, information on some aspects of crystallization temperature and thermal properties has been obtained. The crystallization studies were made using DTA with several uniform rates. The calculations of crystallization activation energies, E_a, and the Avrami parameters, n, were made based on the non-isothermal kinetic theory of Kissinger and the Ozawa’s equations. The DTA data of the samples showed that the first crystallization temperature, T_x1, increases and the second crystallization temperature, T_x2, decreases by increasing the Er concentration. This suggests that the Er substitution had significant effect on the glassification of the BSCCO material due to change on the surface nucleation and increased ionic activities at high temperature region. The activation energy for crystallization, E_a, of the samples was also showed an increase at high Er concentration case. However, the Avrami parameter, n, decreased from 2.5 to 1.7 for x=0.5 and 1.0 samples, respectively. This suggests that the growth mechanism is diffusion-controlled and three-dimensional parabolic growth takes place near the first crystallization temperature. The oxidization rates and the activation barrier for oxygen out-diffusion process, E, was calculated using the TG data. It was found that the total mass gain in the x=0.5 sample is comparably smaller than that of the x=1.0 sample. This shows that the oxygen absorption of the x=1.0 sample is faster than the x=0.5 sample, leading to increase in the oxidization rate in the x=1.0 material.     

量子点在生物化学分析中的应用

量子点（quantumdots,QDs）由于其优异的光学和电学特性,作为新型的荧光试剂探针对生物大分子进行标记,成为近年来迅速发展的纳米材料在生化分析领域的重要应用之一。文章简述了量子点的基本特性,对制备和修饰量子点的各种方法进行比较总结,重点阐述量子点在生物化学分析中的新进展,尤其是对生物大分子的识别和标记作了详细的总结,并提出研究中存在的一些待解决的问题以及今后量子点的研究方向。     

考虑跟随企业搭便车行为的创新企业定价策略研究

文章通过构建博弈模型探讨了存在跟随企业搭便车行为时创新企业的定价策略及定价模式(稳定定价或动态定价),并分析了忠实消费者规模及需求溢出效应等特征对创新企业定价决策与利润的影响.结果表明,无论创新企业采用稳定定价或动态定价模式,跟随企业搭便车行为均会降低创新企业利润,需求溢出效应的增强总能使创新企业和跟随企业均获得更高的...     

分子印迹技术在生化分离分析中的应用

分子印迹聚合物具有高选择性、稳定及实用的特点,在复杂基体中痕量分析物的高选择性分离富集中有着良好的应用前景,近年来在生物样品中的应用尤其引起人们关注.该文分别介绍了分子印迹技术的原理及生物分子印迹聚合物的制备方法,综述了分子印迹技术在氨基酸、生物碱、多肽、蛋白质等生物分离分析中的应用进展.