Nonlinear Current-Voltage Curves for Thin-Film Gas-Sensitive Structures

Current-voltage curves for sensor structures based on thin tin oxide films are examined in various gases. Conditions favoring symmetrical nonlinear curves in the voltage range −30 to 30 V are found.__________Translated from Elektrokhimiya, Vol. 41, No. 6, 2005, pp. 735–737.Original Russian Text Copyright © 2005 by Simakov.Published on the basis of a report delivered at the VII Meeting on Fundamental Problems in Solid-State Ionics (Chernogolovka-2004).     

新型微填充柱－毛细管柱二维色谱系统过程的动力学研究

从色谱动力学角度对新型微填充柱－毛细管柱二维色谱系统过程中双柱条件与流出曲线及柱效之间的依赖关系加以系统研究。结果表明：由于双柱条件之间存在关联，双柱系统流出曲线特征与单柱系统存在一定的差异，流出曲线一阶矩和二、三阶中心矩以及双柱系统的柱效皆由预柱和主柱条件综合确定。     

Diffusion-averaged molecular weights of «nonboiling» crude oil fractions

Summary The successful application of the formerly presented concept of diffusion-averaged molecular weight, M_d, to vacuum residues of crude oils, or their fractions, is described. The samples for establishing the calibration curve, logDvs. logM, were crude oil fractions with polydispersities smaller than 1.1. In a surprisingly good approximation the calibration curve is independent of the origin of these fractions if 500<M<10000. The validity of our calibration curve was demonstrated with more than 10 crude oil residues and with some of their hydrogenation residues [2].     

Theoretical analysis of the performance of a model supercapacitor consisting of metal oxide nano-particles

The factors influencing the electrochemical behaviour of a supercapacitor have been partly examined in this work. The effects of so-called intrinsic parameters, i.e. exchange current density, unit cell length and double layer (DL) capacitance; as well as the so-called application parameters, i.e. cell current, on the cell potential discharge time have been considered. The contributions of each type of capacitors, DL capacitor and faradaic supercapacitor under various states of operation and material have been analyzed, and the competing (compensating) effects of the two types of capacitors as regards to the discharge and power characteristics manifested by current–potential and energy–power (Ragone plots) are elucidated.     

从自模式曲线分辨到渐进类因子分析法

本文对自模式曲线分辨法的发展作了简要回顾，其中特别对近来来迅速发展的一类用于色谱波谱联用仪产生的二维分析数据的渐进类分析法作了详尽的讨论。这些新化学计量学方法的涌现，对复杂的未知分析体系的定性定量分析，将带来深刻的变化。     

Hepatobiliary excretion and brain distribution of caffeine in rats using microdialysis

To investigate the pharmacokinetic mechanism of hepatobiliary excretion and brain distribution of caffeine, this study uses a method based on microdialysis technique and liquid chromatography that allows continuous and concurrent in vivo monitoring of extracellular caffeine in the blood, brain and bile of anesthetized rats following the administration of caffeine (3 or 10 mg/kg, i.v.) through the femoral vein. Dialysates of the blood, brain and bile were directly injected onto the liquid chromatographic system and no further clean-up procedures were required. The study design consisted of two groups of six rats in parallel: the rats of the control group received caffeine (3 or 10 mg/kg, i.v.) alone and those of the cyclosporine treated-group were injected cyclosporine (10 mg/kg, i.v.) 10 min prior to caffeine administration (3 or 10 mg/kg, i.v.). The decline of caffeine in the blood, brain striatum and bile suggested that caffeine had rapid exchange and equilibration between the peripheral compartment and the central nervous system. In addition, the results indicated that caffeine underwent hepatobiliary excretion and was distributed into brain. When cyclosporine was co-administered, the pharmacokinetic parameters were not significantly altered. The results of this study reveal that the pharmacokinetic mechanism of hepatobiliary excretion and brain distribution of caffeine might not relate to P-glycoprotein.     

Study of reaction processes by in-line near-infrared spectroscopy in combination with multivariate curve resolution: Esterification of myristic acid with isopropanol

The acid-catalysed esterification of myristic acid with isopropanol was studied by using near-infrared spectroscopy (NIR) in combination with soft-modeling curve resolution (MCR) methodology with a view to establishing the effect of experimental variables on the reaction kinetics. The reaction was conducted at temperatures above the boiling point of the alcohol, with continuous addition of an isopropanol/water mixture to the reactor. Spectral and concentration profiles were determined by applying soft-modeling curve resolution methodology to a column-wise augmented data matrix containing the spectra for the pure components. MCR profiles were compared with reference values and found to depart from then by less than 3% as %RSE for concentrations and to exhibit correlation above 0.999 for spectra.The reaction kinetics as estimated from the concentration profiles was found to be pseudo-first-order. Also, the pseudo-first-order rate constant was found to depend on the flow-rate of the isopropanol/water mixture and its water content; although the constant decreased with increase in the proportion of water, a content of ca. 15% could be used without important retarding effects on the kinetics. The proposed NIR-MCR method allows the rate constant and the influence of the initial water content to be determined with a view to minimizing consumption of the raw materials and optimizing the experimental conditions.     

Theoretical study of some 1,3-substituted (1,3-diketonato)borondifluorides. Potential energy curve relevant to the barrier crossing reaction

Ab initio Hartree-Fock calculations utilising STO-3G, 3-21G^* and 6-31G^* basis sets have been performed on three neutral and highly polar molecules, (diformylmethine)borondifluoride, (acetylacetonato)borondifluoride and (dibenzylmethine) borondifluoride. The calculated and experimental structures are well correlated when using the HF/3-21G^* basis set, except for the structure parameters involving the boron atom. The HF/6-31G^* basis set does not improve the accuracy in structure calculations. The conformational analysis is in agreement with the experimentally observed C_2v symmetrical structures, where the boron atom is tetrahedrally coordinated. The calculations support a one-dimensional ground state barrier crossing reaction for (dibenzylmethine)borondifluoride, where the phenyl torsion is the most likely reaction coordinate. Both HF/6-31G^* calculations and the second-order Møller-Plesset correction with the 3-21G^* basis set suggest an activation energy of the ground state reaction of about 30 kJ mol⁻¹. The ground state barrier crossing reaction kinetics is evaluated by the Kramers theory. The calculated ground state parameters relevant to the barrier crossing reaction are compared with the experimentally observed excited state values.     

Polyaniline films doped with zinc salts and their properties

It has been found that thin polyaniline films doped with several zinc salts in solutions at pH 5.5 become electroconductive and electroactive in neutral aqueous electrolytes. The shape of the voltammetric characteristics depends on the initial state of the film. The effect of secondary doping withm-cresol is observed for polyaniline complexes with zinc salt of camphorsulfonic acid.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1450–1452, June, 1996.     

水+3-甲基吡啶+溴化钠三元溶液临界跨接现象

采用折射率法在较宽温度范围内研究了溴化钠、3-甲基吡啶和水的临界质量分数分别为0.240、0.192和0.568体系的临界性质, 发现在近临界点临界指数为0.365, 与Fishe重整化值一致. 有效临界指数随着温度逐渐远离临界点, 从0.365下降到0.20左右, 但当排除了“正规项”的影响后, 展现出向平均场理论值0.5单调跨接的行为.