Some properties of three-periodic sphere packings

Some properties of sphere packings are reviewed. Candidates for the least-dense packings of one kind of sphere for different coordination numbers are identified and described. Some topological properties of sphere packing nets are also described.     

Dimethylthiolatobismutane

Synthesis of Some Dimethylthiolatobismutanes Some dimethylthiolatobismutanes of the general formula (CH₃)₂BiSR were synthesized by metathesis reactions from bromodimethylbismutan and sodium thiolates. Some properties, ¹H-NMR spectra and mass spectra of these compounds are described.     

Problems in data retrieval systems for analytical spectroscopy

Some of the existing retrieval systems for analytical purposes based on different spectrometric data are described and compared with systems under development. Requirements concerning input data, coding of fragments or complete chemical structures, preprocessing of input data, and evaluation of the retrieved results are discussed, and some examples are given. Some trends for future developments in this field are outlined.     

水/有机两相体系中催化氧化反应的研究进展

论述了水／有机两相体系中催化氧化反应的一些最新进展。由于采用水溶性催化剂，使得水／有机两相体系中的催化反应具有催化剂与产物容易分离的优点。阐述了水溶性催化剂在催化氧化反应中的应用，列举了一些典型的水溶性配体、水溶性催化剂以及催化氧化反应实例。参考文献21篇。     

Difficulties with topological resonance energy

Some difficulties with topological resonance energy (TRE) are indicated. A strict application of the TRE concept pre-diets cyclobutasdiene to be significantly more aromatic than benzene. The reasons for such an obscure result are analysed. Some algebraic properties of a new graphic polynomial are derived.     

Synthesis and properties of tetrazole-containing oligomers

Linear, star-shaped, and hyperbranched oligomeric compounds containing tetrazole cycles in the main chains are synthesized via the polycondensation (polyalkylation) of N-H unsubstituted bis(tetrazoles), tris(tetrazoles), and tetrakis(tetrazoles) with compounds containing mobile halogen atoms. Some properties of the oligomers are studied. Some of the oligomers are characterized by high density and a large content of nitrogen.     

用动态激光散射法测定悬浮液中颗粒尺寸分布的一些经验

介绍了用动态激光散射仪测定用炸药爆炸法制备的纳米金刚石粉在水悬浮液中的颗粒尺寸分布时,取得的一些经验和教训.指出,在悬浮液样品制备和测定条件选择上的一些重要因素,必须认真对待,才能得到重复性良好的结果.可供从事此项工作的人士参考.     

A New Method for the Characterization of Organic Carbon in Aquatic Systems

Abstract

Some problems in organic carbon characterization are briefly discussed. A new chromatographic multi-method for the direct characterization of organic matter in original waters with the simultaneous determination of UV-Vis, fluorescence, DOC, TIC, and organically bound nitrogen (DON) is described. Some applications with UV-Vis and DOC (“CODOC”) detection are presented.     

Effect of 254 NM Irradiation on Mercury Vapor

Abstract

Some observations are reported on the decay of the mercury atomic concentration as a result of irradiation with 254 nm radiation. The rate of fall of the atomic absorption is linearly related to the intensity of incident 254 nm radiation. Some possible mechanisms are suggested.     

Preparation et oxydation de dialkylgermyl- et stannyltetraphenylporphyrines

Some new organo-germanium and -tin tetraphenylporphyrins were obtained. Their behaviour in solution shows that they are readily oxidized into peroxides by light and oxygen. Some of these derivatives must be prepared under especially mild experimental conditions, indicating a surprising unstability for metal IVB — carbon bonds.     

Brände und Explosionen vermeiden

Fires and explosions have cost many, too many lives, severed a plethora of humans and caused enormous expenses, not only in research and industry but even more in private life. Some basic principles of combustion processes, sources of ignition and the properties of combustible materials are illustrated and the knowledge of these will help to avoid many of these cases. Some experiments for lecture demonstrations are presented.     

Role of Frontier Molecular Orbital Symmetry of Reagents in Redox Catalytic Indicator Reactions

Some hypotheses are discussed for the nature of “inhibited” or “kinetically hindered” redox reactions, which are employed as indicator reactions in kinetic analytical methods. Some reactions are considered as examples to demonstrate that redox reactions are kinetically hindered because the key frontier orbitals of the reagents differ in their symmetry types. It is suggested that the redox reactions of this type be considered forbidden by inconsistency between the symmetry types of the key frontier orbitals.     

腈水合酶及其在丙烯酰胺生产中应用的研究进展

对近年来国内外腈水合酶的研究进行了回顾,就腈水合酶的种类、分布、生理合成调节、结构特点、反应机理、光敏性、热稳定性等方面及影响酶活性的几个主要因素做了具体的阐述.并进一步探讨了其在工业中的应用和发展,提出了一些建议和设想.     

A cautionary note on the use of the frozen-core approximation for correlation energy calculations involving alkali metals

Test calculations have shown that correlation energies calculated using the frozen-core approximation in programs, such as the Gaussian series, that assume the lowest MOs to be the core orbitals may be significantly in error. Some valence orbitals in systems involving the heavier alkali metals and electronegative elements have lower energies than the highest core orbitals of the metal and are therefore erroneously omitted from the correlation energy calculation. Some examples are discussed.     

Controlled potential electroanalysis

Some fundamental principles involved in controlled potential electroanalysis are discussed. A potentiostat is described which automatically maintains the potential of a working electrode constant during an electrolysis. Cells for different applications of controlled potential electrolysis are described. Some typical applications are reviewed, including electrogravimetric determinations of metals, electrolytic separation of metals with mercury and platinum cathodes prior to polarographic analysis, coulometric analysis, identification of the oxidation states that correspond to polarographic waves, and electrolytic preparation of organic and inorganic compounds.     

Functionalization during anionic polymerization of heterocycles

General approaches to the synthesis of functional polymers based on heterocycles are considered. Most attention is paid to the living anionic polymerization with functionalization through initiation or deactivation. It is shown that demands of both high molecular weight and quantitative functionalization cannot be completely satisfied. Some examples of preparing functional polyethers and polyesters are given, namely dinitrophenyl derivatives and vinyl ether macromonomers of poly(ethylene oxide) as well as methacrylate macromonomers of β-propiolactone. Some of perspective applications of these polymers are also touched upon.     

锂无机固体电解质*

全固态锂离子二次电池具有更大能量密度和更高的安全使用性能,在未来的电动汽车和蓄能电站上有很好的应用前景。本文对一些典型的锂无机固体电解质进行分类讨论,对它们的性能、结构和导电机理进行评述。这些固体电解质具有较高的离子导电率,是目前的研究热点。文章总结了影响其导电率的几个重要因素以及作为理想锂无机固体电解质的几个基本要求。     

Application of pulse radiolysis to the study of the chemistry of radical anions

The application of pulse radiolysis to the measurement of rates of reaction of aromatic and olefinic radical anions in organic solvents is discussed, emphasis being placed on the problem of reaction of the radical anion with the radiolytically-generated-counter ion. Some previous experiments of the authors that utilised tetrahydridoaluminate salts to scavenge the counter ion are reviewed. Some new data on the rates of electron transfer from aromatic-radical anions to some substituted styrenes are presented and experiments aimed at using organic amides as solvents for these studies are described.     

Modern Sample Preparation Methods in Chemical Analysis

 The choice of the sample preparation method is crucial in chemical analysis, since it is often the most critical and time-consuming step of an analytical process. Some of the older methods are laborious, expensive, and offer no scope for automation. The newer sample preparation techniques can give higher yields, better sample clean-up, cost effectiveness worker safety and environmental protection. Some novel sample preparation methods are described their potential is illustrated with emphasis on bioanalytical applications.     

二点滴定法研究

就二点滴定法的原理，方法和应用进行了讨论，导出了二点滴定法计算公式。讨论了滴定剂加入量与测定结果准确度的关系。已用本法对标样样液及试样进行了多次测定，测定结果相对误差及相对标准偏差约０．２％。本法简便，快速，准确，且昨达于任何滴定类型的通用方法。