Methods for Optimizing Properties of Polymer Electrolytes Intended for Lithium Batteries

New plasticized polymer electrolytes, based on chlorinated derivatives of polyvinyl chloride, are studied by infrared and impedance spectroscopy. Morphological and electrochemical properties of the electrolytes depend on the nature of the lithium salt and liquid plasticizer and on the technology. Galvanostatic cycling data for lithium batteries based on Li-LiMn₂O₄ and Li-V₆O₁₃ and these electrolytes are presented.     

Rules for selection of oxide catalysts for oxidative dehydrocombination of hydrocarbons

Based on the mechanism of oxidative dimerization of hydrocarbons the rules for the selection of catalysts for this kind of reactions has been discussed. It has been shown that an efficient dehydrodimerization catalyst must contain on its surface electron acceptor centers (metal cations) of moderate strength, strongly bound nucleophilic oxygen, and possess the corresponding collective properties. The elements have been discussed, the oxides of which satisfy the above requirements.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 3, pp. 366–370, May–June, 1988.     

Release Coatings on Apparatus for Fabrication of Electrodes for Chemical Power Sources

The influence exerted by the composition and properties of formulations for electrodeposition on the characteristics of release coatings on rollers for rolling of ribbon-type cathodes is described. A composition based on VUPFS-35 resin and magnesium zirconate powder is recommended for use in the formulations.     

Potential of FTIR spectroscopy for analysis of tears for diagnosis purposes

It has been widely reported that the tear film, which is crucially important as a protective barrier of the eye, undergoes biochemical changes as a result of a wide range of ocular pathology. This tends to suggest the possibility of early detection of ocular diseases on the basis of biochemical analysis of tears. However, studies of tears by conventional methods of biomolecular and biochemical analysis are often limited by methodological difficulties. Moreover, such analysis could not be applied in the clinic, where structural and morphological analyses by, mainly, slit-lamp biomicroscopy remains the recommended method. In this study, we assessed, for the first time, the potential of FTIR spectroscopy combined with advanced chemometric processing of spectral data for analysis of raw tears for diagnosis purposes. We first optimized sampling and spectral acquisition (tears collection method, tear sample volume, and preservation of the samples) for accurate spectral measurement. On the basis of the results, we focused our study on the possibility of discriminating tears from normal individuals from those of patients with different ocular pathologies, and showed that the most discriminating spectral range is that corresponding to variations of CH₂ and CH₃ of lipid aliphatic chains. We also report more subtle discrimination of tears from patients with keratoconus and those from patients with non-specific inflammatory ocular diseases, on the basis of variations in spectral ranges attributed notably to lipid and carbohydrate vibrations. Finally, we also succeeded in distinguishing tears from patients with early-stage and late-stage keratoconus on the basis of spectral features attributed to protein structure. Therefore, this study strongly suggests that FTIR spectral analysis of tears could be developed as a valuable and cost-saving tool for biochemical-based detection of ocular diseases, potentially before the appearance of the first morphological signs of diseases. Combined with supervised modelling methods and with use of a spectral data base acquired for representative patients, such a spectral approach could be a useful addition to current methods of clinical analysis for improvement of patient care.

Comparison of methods for characterizing microporous membranes for plasma separation

To design membranes suitable for therapeutic use, the relationship between membrane structure and permeability needs to be studied. In this work, the solute permeability of small tubular membranes for plasma separation was determined by using radioisotope-labeled solutes. Through analysis of data on solute and pure water permeability and on water content, by means of a tortuous pore model that we have proposed, we can obtain pore diameter, surface porosity and tortuosity. Membrane structure was also analyzed by mercury intrusion and scanning electron microscopy, and the results were compared with each other. The mercury intrusion method is unsuitable for the structural analysis of polymer membranes because of the damage and/or expansion resulting from highly elevated pressure. The tortuous pore model is recommended for the elucidation of membrane structure.     

Conditions for attainment of thermodynamic equilibrium for the Ag/Hg system

Following a previous study on the influence of the size of silver particles used in dental alloys on the conditions for the attainment of thermodynamic equilibrium, results are presented on the influence of the particle shape factor. Calorimetric results obtained using different particle forms are compared with those derived from a mathematical model in which it is considered that silver particles can assume a spherical or cylindrical (flat or narrow) shape. It appears that the thermal effects obtained by computation are closer to those obtained by calorimetric experimentation when the sphere of the model is transformed into either a disc or a rod.     

Use of stable isotopes as surrogates for radionuclides for security studies

During the past decade, interest has increased in qualifying and quantifying the threat posed to the public by the illegal use of radionuclides. In order to take investigations beyond the laboratory bench into more realistic scenarios, environmental and safety considerations dictate that these studies be performed on stable and benign surrogates. This paper discusses some of these studies, specifically the use of cerium dioxide for actinide ceramics and calcium and natural strontium ceramics for those based on ⁹⁰Sr.     

Naphthalene sulphonic acids--new test compounds for characterization of the columns for reversed-phase chromatography

Non-substituted naphthalene sulphonic acids are strong acids, which are completely ionised in aqueous and aqueous-organic solutions. Because of repulsive electrostatic interactions, they are more or less excluded from the pores of the column packing materials commonly used in reversed-phase chromatography. The ionic exclusion can be suppressed by increasing the ionic strength of the mobile phase. In aqueous sodium sulphate solutions, very good selectivity was observed for isomeric naphthalene di- and tri-sulphonic acids, allowing reversed-phase separations of these strongly ionic compounds without addition of ion-pairing reagents to the mobile phase. The retention of the isomeric acids increases proportionally to the dipole moment, which can be explained by its effect on increasing exposure of the naphthalene ring to hydrophobic interactions with the non-polar stationary phases. Chromatographic behaviour of isomeric naphthalene di- and trisulphonic acids was investigated on 25 different columns for reversed-phase chromatography. The elution order of the isomers is the same on all the columns, but very strong stationary phase effects were observed on the retention and on the band asymmetry, depending on polar interactions with residual silanol groups and other polar adsorption centres in the stationary phases. These effects are independent of the organic solvents, as the tests are performed in purely aqueous mobile phases and allow classification of the columns into several groups.     

Preparation of PVA membrane for immobilization of GOD for glucose biosensor

A membrane was prepared using polyvinyl alcohol (PVA) with low and high degree of polymerization (DOP), acetone, benzoic acid (BA) and was cross-linked by UV treatment. Membrane composition was optimized on the basis of swelling index. Membrane prepared with 12% low DOP and 8% high DOP of PVA, 2% BA, dissolved in buffer containing 20% acetone and cross-linked with UV treatment exhibited lower swelling index. Fourier transform infrared (FTIR) study of the membranes showed appearance of a strong band at approximately 2337 cm(-1) when UV was used for cross-linking in the presence of benzoic acid. Scanning electron microscope (SEM) study revealed that membrane cross-linked with UV treatment was smoother. Glucose oxidase (GOD)-PVA membrane was associated with the dissolved oxygen (DO) probe for biosensor reading. Glucose was detected on the basis of depletion of oxygen, when immobilized GOD oxidizes glucose to gluconolactone. A wide detection range, 0.9-225 mg/dl was estimated from the linear range of calibration plot of biosensor reading. Membranes were reused for 32 reactions without significant loss of activity and stored for 30 days (approximately 90% activity) at 4 degrees C. Membranes were also used with real blood samples.     

Potentialities and prospects for the use of alkaline phosphatases for determining metal ions

The published data on the nature, strength, and mechanism of metal ion effect on the catalytic activity of alkaline phosphatases and their apoenzymes of different origins are systematized and discussed. Procedures for determining metal ions are described. These procedures are based on the activating, inhibitory, and reactivating effects of metal ions on enzymes and apoenzymes. The approaches to the intentional improvement of the sensitivity and selectivity of determining metal ions are considered. Prospects are outlined for using alkaline phosphatases isolated from different sources in chemical analysis for determining metal ions in different samples.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 3, 2005, pp. 247–263.Original Russian Text Copyright © 2005 by Muginova, Zhavoronkova, Shekhovtsova.     

Design of molecular precursors for nanomaterials

This work is focused on the synthesis of bimetallic oxide prepared by non-hydrolytic sol–gel method using the chemie douce approach. The bimetallic oxide was characterized by using various analytical techniques. Elemental analysis showed consistency with the formulation. From XRD, SEM and TEM studies, it is concluded that precursor chemistry has a significant effects on the surface chemistry of metal oxide on calcinations and as well as synthetic routes. XRD patterns show that an enhanced homogeneity on calcinations. Use of these metal oxides has commercial importance in future for sensor devices.     

Affinity Chromatography-Based Assays for the Screening of Potential Ligands Selective for G-Quadruplex Structures

DNA G-quadruplexes (G4s) are key structures for the development of targeted anticancer therapies. In this context, ligands selectively interacting with G4s can represent valuable anticancer drugs. Aiming at speeding up the identification of G4-targeting synthetic or natural compounds, we developed an affinity chromatography-based assay, named G-quadruplex on Oligo Affinity Support (G4-OAS), by synthesizing G4-forming sequences on commercially available polystyrene OAS. Then, due to unspecific binding of several hydrophobic ligands on nude OAS, we moved to Controlled Pore Glass (CPG). We thus conceived an ad hoc functionalized, universal support on which both the on-support elongation and deprotection of the G4-forming oligonucleotides can be performed, along with the successive affinity chromatography-based assay, renamed as G-quadruplex on Controlled Pore Glass (G4-CPG) assay. Here we describe these assays and their applications to the screening of several libraries of chemically different putative G4 ligands. Finally, ongoing studies and outlook of our G4-CPG assay are reported.     

EQCM for In-depth Study of Metal Anodes for Electrochemical Energy Storage

Electrochemical quartz crystal microbalance(EQCM) is a powerful tool to study the mass change and charge transfer during electrochemical process. The mass change on the electrode surface can be monitored with high precision and high sensitivity, making it possible to analyze the in-depth mechanism of electrode reactions. The application of metal anodes has exhibited great potential for the future energy storage devices for the elevated capacity. Herein, we review the research progress utilizing EQCM for metal anodes, including the deposition/dissolution process, the side reactions, the effect of additives, etc. Furthermore, we also put forward a perspective on research of the mechanism and performance improvement of metal anodes.     

Matrix elements for operators for physical quantities in one-configuration functions of radicals

Some basis vectors are constructed for singly and doubly excited configurations of molecules and radicals for the method of configuration interaction in the second-quantization representation. The matrix elements of the Hamiltonian are derived for these. A method is given for calculating bond orders, transition moments, spin densities, and electron densities on atoms in the configuration-interaction method. An analog of Brillouin's theorem is obtained for radicals.Read at the II-nd Ukranian Republic Symposium on Quantum Chemistry. (Kiev, Dec. 1968).     

Alternative procedure for the purification of the heat-stable enterotoxin of enterotoxigenic Escherichia coli pathogenic for calves

A method for purification of the heat-stable enterotoxin (ST) of enterotoxigenic Escherichia coli (ETEC) strains (C1444 and B41) pathogenic for calves and some physiochemical properties of the ST are described. The method involved ultrafiltration on PM-10 and UM-2 Diaflo membranes, acetone fractionation, ion-exchange chromatography on AG 1-X2, chromatofocusing and a combination of hydrophobic interaction chromatography on octyl-Sepharose CL-4B and gel-permeation on Bio-Gel P-2. Polyacrylamide gel electrophoresis in sodium dodecyl sulphate of fluorescamine-labeled purified, reduced and alkylated ST preparations revealed a single band with approximate molecular masses of 2500 and 2200 for the C1444 and B41 STs, respectively. For the C1444 ST, the final purification achieved was approximately 27,000-fold on the basis of absorbance at 280 nm per mouse effective dose. However, it was 2000-fold when calculated on the basis of mg protein per effective dose (5 ng). Amino acid composition of the C1444 ST was found to be different from that of the B41 ST suggesting that the ST produced by bovine isolates may be heterogeneous in their structure.     

Effects of fungal laccase immobilization procedures for the development of a biosensor for phenol compounds

Fungal laccase was immobilized on carbon-fiber electrodes using classical methods: physical adsorption, glutaraldehyde, carbodiimide and carbodiimide/glutaraldehyde. The highest biosensor response was obtained using carbodiimide/glutaraldehyde for coupling laccase to carboxyl groups on the carbon fibers. In this method, different percentages of glutaraldehyde had important effects on the sensitivity of the biosensor, the best percentage of glutaraldehyde being 10% (m/v). The behavior of the obtained biosensor was investigated in terms of sensitivity, operational range, pH and applied potential. The developed biosensor showed an optimum response at pH 5.0 and at an applied potential of -100 mV. The immobilized laccase retained a good activity for over 2 months.     

Intrinsic barrier for protonation of radical anions

Ab initio calculations on radical anions show that, counterintuitively, protonation on the radicaloid carbon is favored. In the case of radical anions derived from acrylonitrile and acrylaldehyde, protonation on the heteroatom is less favored than protonation on the radicaloid carbon. However, in nitroethylene, the preferred protonation site is on the nitro oxygen in accordance with experimental observation.     

Prospects for the development of bronchodilators

The review considers and evaluates the methodology for the design of antiasthmatic bronchodilators, selective stimulants of β₂-adrenergic receptors in bronchi (β₂-agonists), for the treatment of bronchial asthma. The influence of the structure of the compounds on the resistance to the enzyme catechol-O-methyltransferase and their selectivity for β₂-adrenoreceptors are described. Examples of the influence of the structure of the drugs on the duration of their action on β₂-adrenoreceptors are given. The review presents schemes for the synthesis of drugs commonly used for the treatment of bronchial asthma, such as salbutamol and formoterol, which are shortand long-acting β₂-agonists, respectively. Data on the selectivity and efficacy of action of medicinal drugs on β₂-adrenergic receptors are considered.     

A new tool for the post-process modification of chips by nanostructures for chemical sensing

The tool is built up on moving plates driven by step-motors for precise location of sensors chip on the wafer to perform post-processing of the chip. The tool can make chemical or electrochemical deposition and etching for the chip modification after wafer processing. Each chip on the wafer can be modified with different process. The deposition from solutions and wet etching is controlled by a flow-system and power source if it is necessary. Techniques for ordered nanostructures creation using the tool were also developed. The tool helps to improve properties of microsensors fabricated on the chip by thin-film and semiconductor technology.     

基于化学缔合统计理论的链状流体状态方程

基于化学缔合统计理论的链状流体状态方程(EOS)能够反映实际分子的形状、链节成链、缔合等具体信息,在实际流体热力学性质计算中有着广泛应用.一般的链状流体EOS仅考虑相邻链节间的相关性,我们则借助统计力学和计算机模拟结果在模型中纳入了相间链节间的相关性,获得的硬球链流体(HSCF)模型能够更好地预测模型流体的压缩因子和第二维里系数.以HSCF为参考,引入方阱色散微扰项获得了实际方阱链流体(SWCF)EOS;结合根据黏滞球模型导得的缔合项,进一步构建了缔合流体EOS.最近,我们根据微扰理论和积分方程方法又开发了一新的变阱宽方阱链流体(SWCF-VR)模型.SWCF和SWCF-VREOSs可很好地用于计算小分子、聚合物、离子液体等纯流体及混合物的相行为、热焓、表面张力、黏度等热力学及传递性质,显示了模型良好的工程应用价值.本文就本课题组多年来在自由空间范畴内基于化学缔合统计理论开发链状流体EOS及其实际应用作系统的总结.