Investigation of the products of the ozonolysis of larixol

On the ozonization of larixol in methanol followed by treatment with ammonium chloride, the main reaction products were 15,16,20-trisnorlabd-6-ene-8,13-dione and 6-hydroxy-8,13;8,14-diepoxy-15,20-bisnorlabd-14-one. When ozonization was performed in methanol in the presence of dimethyl sulfide or in methylene chloride in the presence of pyridine, 6,14-dihydroxy-8,13;8,14-diepoxy-15,20-bisnorlabdane and 6-hydroxy-14,50,20-trisnorlabd-8,13-dione predominated in the reaction products.     

缺Zn症患儿微量元素水平的样本特征分析及其临床补Zn治疗的评价

测定了150例缺Zn症患儿及健康儿发样中的Zn、Ca、Mg及Fe四元素水平．采用主成分分析法．将高维空间中的样本点映射到低维空间中来观察，研究其样本特征，评价临床补Zn治疗措施．结果瑶明：缺Zn症患儿体内缺Zn是病理的主要方面，但往往同时伴有其它微量元素水平偏低现象，临床缺Zn症状的表现可能为多种元素综合效应的反映．因此临床治疗不能单纯考虑朴Zn，还应结合患儿体内其他元素水平的具体情况，考虑其他元素的补给．治疗才能奏效显著．     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Effect of Pore Structure of Al-Co-Mo Catalyst on the Rate of Various Pathways of Hydrofining of Oil Residues

Evolution in the activity and texture of the Al-Co-Mo catalyst in hydrofining of black oil is studied. The catalyst efficiency in desulfurization, deasphalting, and demineralization of black oil is estimated as dependent on the catalyst pore structure and process conditions.     

Structure of the products of the photoreaction of osthole

The results are given of a study of the photoreaction of osthole in chloroform and acetophenone. It has been shown that when it is irradiated in the latter solvent the cyclization characteristic for coumarins takes place at the double bonds both in the 3,4- position of the coumarin ring and in the side chain, leading to the formation of cyclobutane structures.Leningrad Sanitary-Hygienic Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 165–168, March–April, 1980.     

Study of electron states of solids by techniques of electron spectroscopy

Studies of valence bands and core levels of solids by photoelectron spectroscopy are described at length. Satellite phenomena in the core level spectra have been discussed in some detail and it has been pointed out that the intensity of satellites appearing next to metal and ligand core levels critically depends on the metal-ligand overlap. Use of photoelectron spectroscopy in investigating metal-insulator transitions and spin-state transitions in solids is examined. It is shown that relative intensities of metal Auger lines in transition metal oxides and other systems provide valuable information on the valence bands. Occurrence of interatomic Auger transitions in competition with intraatomic transitions is discussed. Applications of electron energy loss spectroscopy and other techniques of electron spectroscopy in the study of gas-solid interactions are briefly presented.     

A study of the stability of aqueous suspensions of functionalized carbon nanotubes

The properties of aqueous suspensions of carbon nanotubes have been studied as depending on the conditions of their functionalization in a mixture of sulfuric and nitric acids. The elemental composition and contents of carboxyl, lactone, and hydroxyl groups in carbon nanotubes have been determined at different durations and temperatures of functionalization. The influence of functionalization conditions on the value of the electrokinetic potential of carbon nanotubes in aqueous suspensions and the nanotube solubility in water has been investigated. It has been found that the absolute value of the electrokinetic potential of nanotubes and their solubility in water increase with both the duration and temperature of functionalization due to a rise in the number of functional groups on their surface. The optimal regimes of functionalization of carbon nanotubes have been determined from the point of view of preserving their structure and stability in aqueous dispersions.     

Elucidation of the Structure of Products of Triphenylphosphine Electrooxidation in the Presence of Camphene

The structure of the products of anodic oxidation of triphenylphosphine in the presence of camphene carried out in acetonitrile with sodium perchlorate as supporting electrolyte has been studied. The major product, triphenylphosphine oxide, has been isolated from the solution in the form of cocrystals of free triphenylphosphine oxide and its complex with sodium perchlorate. The molecular structure of the cocrystals has been studied by X-ray diffraction analysis. Triphenylcamphenylphosphonium perchlorate, bornylacetamide, and a terpene compound with triphenylphosphonium and acetamide substituents in the cycle have been detected by NMR ¹³C as the electrolysis side products.

     

Investigation of the products of the ozonolysis of larixol

On the ozonization of larixol in methanol followed by treatment with ammonium chloride, the main reaction products were 15,16,20-trisnorlabd-6-ene-8,13-dione and 6-hydroxy-8,13;8,14-diepoxy-15,20-bisnorlabd-14-one. When ozonization was performed in methanol in the presence of dimethyl sulfide or in methylene chloride in the presence of pyridine, 6,14-dihydroxy-8,13;8,14-diepoxy-15,20-bisnorlabdane and 6-hydroxy-14,50,20-trisnorlabd-8,13-dione predominated in the reaction products.Institute of Chemistry of the MSSR Academy of Sciences, Kishinev, and Institute of Organic Chemistry of the Bashkir Branch of the USSR Academy of Sciences, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 577–584, September–October, 1986.     

Thermodynamic parameters of solvation of nonelectrolytes in aqueous solutions of amides of carboxylic acids

Interaction and reorganization contributions to solvation enthalpies of nonelectrolytes in aqueous solutions of amides of carboxylic acids with different degree of N-substitution and N-methylpyrrolidone are calculated. The data are discussed using structurally thermodynamic characteristics of water-amide systems obtained by us previously. It is found that the type of concentration dependence of the solvation enthalpy of nonelectrolytes in all solutions investigated is determined by the type of reorganization component. It is shown that the highest solvation exothermicity of nonelectrolytes in water is due to the lowest value of the reorganization contribution in spite of that nonelectrolytes interact weaker with water than with non aqueous components.     

Laboratory of Spectrochemical Analysis of the Research Institute of Physics of St. Petersburg State University

The events which initiated the organization of the Laboratory of Spectrochemical Analysis and the Division of Optics of the Department of Physics of Leningrad State University in 1948 are set forth. The steps in the growth of the laboratory and the transformations in the main fields of scientific research are considered. The important role of the laboratory staff at all steps of its work is noted both in the development of methods of spectrochemical analysis and their application as well as in training students and highly skilled personnel in analytical spectroscopy. The researchers of the laboratory who made a great contribution to analytical spectroscopy are listed.     

Comparative study of the structure of products of plasma modification of globular and fibrillar proteins

The molecular-mass distribution and amino acid composition of globular (albumin, lysozyme) and fibrillar (collagen) proteins subjected to treatment in electron-beam plasmas of various gases were experimentally studied. The samples were treated in the forms of powders and freeze-dried thin films. The electron-beam plasma treatment of powdered collagen resulted in the formation of low-molecular-mass compounds only. The modification of albumin and lysozyme was accompanied by polymerization of the proteins against the background of insignificant degradation. The plasma-stimulated processes occurred in the surface layer of powder particles, whereas the bulk of the sample remained intact. The degradation and polymerization processes in thin films of globular proteins occurred throughout the entire volume of the sample.     

Mechanism of self-assembly of rigid-chain macromolecules of cellulose ethers in solutions

With the aid of the turbidity-spectrum method, the cloud-point method, X-ray analysis, and polarization microscopy and the use of a polarization-photoelectric apparatus, the sizes of supramolecular particles are determined and the liquid-crystalline phase transitions and the structure of cellulose ether solutions are studied in a wide composition range. As the concentration of the polymer in solution increases, the sizes of light-scattering particles tend to increase from several nanometers to several thousand nanometers. This effect is the most pronounced during formation of the liquid-crystalline phase. The “packet” mechanism of self-assembly of macromolecules is advanced. For cyanoethyl cellulose macromolecules, the coilhelix transition is observed with an increase in the concentration of the polymer in solution. For the cyanoethyl cellulose-dimethylacetamide system, the method for calculating the amount of macromolecules in supramolecular particles in both isotropic and anisotropic regions is suggested.     

Quantum-chemical study of tautomers of reduced forms of anthraquinone

The quantum-chemical method B3LYP/6-311G(d,p) was used to calculate structural parameters of four conformers of 9,10-dihydroxyanthracene, two conformers of 9-hydroxyanthrone, and the corresponding anions, dianion, and radical anion. The energy of 9,10-dihydroxyanthracene in a gas phase is higher and in aqueous solution lower than the energy of 9-hydroxyanthrone. The dianion can exist exclusively in a polarizable medium.     

Improvement of the efficiency of electrochemical refining of cobalt

To improve the purity of cobalt produced by electrochemical refining, the optimal electrolyte composition and electrolysis mode were determined and a method for diminishing the electrochemical activity of impurity metals in anodic dissolution of the raw metal and a system for deep purification of the electrolyte solution to remove impurities were developed. Cathode deposits with a conditional cobalt content exceeding 99.999 wt %, found in an analysis for the 11 main impurities, were obtained by using the above results in refining of K1A cobalt (≥99.30 wt % Co) in an electrolyzer of distinctive design.     

Formation of particles of metal hydroxides in water solution of polymer

The stages of the formation of metal hydroxide particles in water medium were described. The first stage is the formation of complexes between the stabilizer and metal ion or of metal polyions containing a few metal ions. Dependence between the number of metal ions in polyion and its charge on the pH is described. The second stage is the formation of the metal hydroxide particles by the aggregation of polyions or their adsorption on/in the stabilizer. The distribution of the polyion number in the particles in polyion aggregation is described by the equation p(k) = k(ks-1)(k-1)/ksk and in polyion adsorption on/in the stabilizer particles is more narrow and is described by the equation p(k) = exp(-ks)/ks(-k)/k!, where k and ks are the number and the average number of polyions in the particle.     

自由基聚合中平均聚合度的学习

自由基聚合是《高分子化学》课程的重要一章 ,其中 ,平均聚合度是自由基聚合微观动力学的重要研究内容。正确理解其概念 ,掌握各种数学表达式的涵义 ,对高分子化学的学习十分有益 ,本文对不同终止和链转移情况下平均聚合度的表述方法进行了讨论     

Application of exploratory data analysis for the characterization of tubular wells of the North of Brazil

Roraima is located in the extreme North of Brazil, in the Western Amazon Region. The groundwater has an important role in the public supply of potable water on the Roraima State. The objective of this work is the application of PCA (Principal Component Analysis) and HCA (Hierarchical Cluster Analysis) for the characterisation of tubular wells of the Roraima State, as regards physical–chemical composition of water. The parameters analyzed in laboratory were the following ones: pH, electric conductivity, Total Hardness, Total Alkalinity, Bicarbonate, Calcium, Potassium, Magnesium, Nitrate, Chloride, Total Iron. The physical–chemical analyses, were carried out during the months of September and October 2000 (winter, period of rains). The laboratory analysis was performed using classical methods (titrimetry and uv–visible spectroscopy), the samples were processed in agreement with the Standard Methods for Examination of Water and Wastewater.The physical–chemical analyses, were accomplished in September and October 2000. In physical–chemical terms, the groundwater samples analyzed do not indicate any restriction to human consumption and the two chemometric methods of exploratory data analysis: PCA and HCA are efficient for the discrimination of bicarbonated (tubular wells locateds in the South of the Roraima State) and not bicarbonated (tubular wells locateds in the North of Roraima) groundwater.     

Effect of modification of light-harvesting complex II on fluorescence properties of thylakoid membranes of Arabidopsis thaliana

The 77 K chlorophyll fluorescence spectra of Arabidopsis thaliana mutants deficient in lipid fatty acid desaturation have been used in order to further explore the influence of the modification of LHC II after mutation and proteolitic treatment on the energy transfer between the chlorophyll-protein complexes, as well as on the structure-function relationship in the supramolecular complex of Photosystem II. The gaussian decomposition and analysis of the fluorescence bands associated with PS II complex show the controversial action of the trypsin in the investigated thylakoid membranes. This reveals that the organization of PS II complexes is different in the wild type and both mutants indicating altered connection between the LHC II and the RC core complexes of PS II in both mutants. The results obtained demonstrate that different amounts of oligomer and monomer forms of LHC II in the mutants (LK3 and JB67), arising from lipid modification, are responsible for different proteolytic action in their thylakoid membranes.