Toward optimisation of electrolytic reduction of solid chromium oxide to chromium powder in molten chloride salts

Electrochemical reduction of solid Cr₂O₃, in the form of an assembled cathode of porous pellets attached to a current collector, to chromium powder was investigated in molten CaCl₂ and a molten equimolar mixture of CaCl₂ and NaCl. The study focused on the influence of pellets preparation conditions, cell voltages and temperatures on the reduction process. Analyses were reported of the characteristics of the current-time plots of the constant voltage electrolysis under different conditions, cyclic voltammograms of solid Cr₂O₃ in the molten equimolar mixture of CaCl₂ and NaCl, the microstructures and elemental compositions of the reduced pellets. Particularly, attention was given to the intermediate product of the electrolysis, calcium chromites of various stoichiometries, aiming to achieve a better understanding and optimisation of the reduction process.     

Preparation of activated carbon microspheres from phenolic-resin by supercritical water activation

Supercritical water (SCW) has been employed as an efficient activating agent for the preparation of activated carbon microspheres (P-ACS) with developed mesopores from phenolic-resin. Several processing factors that influenced the activation reaction, including activation temperature, activation duration, supercritical pressure and water flow rate were investigated. Increasing activation temperature and duration lead to larger porosity and higher specific surface area as demonstrated in the samples. Supercritical pressure change has little effect on the activation; however, there are indications that a slight increase in mesoporosity can be obtained when the pressure was raised to 36 MPa or higher. Higher water flow rate slightly enhanced the development of microporosity but had little effect on the mesoporosity. Compared with the traditional steam activation, SCW activation can produce P-ACS with more mesoporosity and higher mechanical strength.     

Photocatalysis of V-bearing rutile on degradation of halohydrocarbons

Natural rutile TiO₂ shows photocatalysis on degrading trichloroethylene and tetrachloroethylene. In natural rutile, V, Fe, Cu, etc. substitute for Ti, resulting in lattice distortions and defects. We found that rutile, after heating, quenching and electron irradiation, changes its surface characteristics and photoactivity. The quenched rutile has the highest concentrations of adsorbed water and V on its surface, resulting in high photoactivity. For example, quenching at 1273 and 1373 K significantly improved photoactivity of rutile. The heated rutile also increased the concentration of adsorption water on the surface, e.g., rutile heated to 1273 K improved degradation rate of halohydrocarbons. On the contrary, electron irradiation decreased the concentration of adsorbed water on the rutile’s surface, which results in lower degradation rate for trichloroethylene. Therefore, heating and quenching over 1237 K improve the photocatalytic efficiency of the natural V-bearing rutile on degrading halohydrocarbons. The XRD spectra of the rutile samples showed that heating, quenching and electron irradiation did not result in formation of new phases or phase transitions.     

基于VB和ADO的机考批改系统

即时通信目前有4种主要协议:即时信息和空间协议(IMPP)、空间和即时信息协议(PRIM)、针对即时通信和空间平衡扩充的进程协议SIP(SIMPLE)以及XMPP。XMPP是其中最重要的协议之一,是基于XML流的即时通信协议。首先简单介绍XMPP出现的背景,然后详细解析XMPP中的XML流、XML节和JID等基本概念,采用一些实例说明这些基本概念在即时通信中的应用,最后还对XMPP的互通性、安全性及加密特征进行了讨论。     

俄罗斯基于超辐射机理相对论返波管实验研究进展

基于超辐射机理相对论返波管能产生高峰值功率、高峰值转换效率、快速上升前沿的纳秒／亚纳秒微波脉冲，正成为高功率微波源系统小型化的新技术途径．本文介绍了近几年来俄罗斯方面对超辐射返波管器件的实验研究情况，重点报道了Ka波段和X波段超辐射返波管器件的最新进展，并指出发展趋势及存在的一些关键技术问题．     

The Influence of Cue Type on Backward Inhibition.

Backward inhibition is proposed as a process of lateral inhibition that operates during response selection in task switching, reducing interference caused by the most recently abandoned task set. The effect has been observed across a wide range of contexts but is eliminated by using spatial location to cue tasks (K. D. Arbuthnott & T. S. Woodward, 2002). The present studies replicated this finding, showing that spatial cues are also associated with greater response congruity than verbal cues, consistent with the lateral inhibition model. Spatial cues may introduce greater discriminability between competing category-response rules, reducing the need for lateral inhibition. However, when participants named the task before target presentation, backward inhibition was observed with spatial cues, suggesting that verbalization increased competition between sets, despite spatial localization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electronic properties of polymethine systems. 10. Electron structure and absorption spectra of cyanine bases

Complex quantum-chemical and spectral studies of the features of the electron structure and absorption spectra of the bases' derivatives of the symmetrical cyanine dyes are performed. It is found that moving from cationic cyanines to their neutral bases is accompanied by a drastic increase in the bond length alternation, equalizing the electron densities at atoms in the chromophore and by sharp shifting up of the molecular levels. Spectral bands in the absorption spectra of the bases are essentially wider and lower intensive and hypsochromically shifted, what is suggested to be connected with different nature of the first electron transition in the cyanine dyes and their bases.     

The influence of gold nanoparticle modified electrode on the structure of mercaptopropionic acid self-assembly monolayer

The comparison of assembly structure and property of mercaptopropionic acid (MPA) self-assembled monolayers (SAMs) on gold nanoparticle modified electrode (nanogold electrode) with that on planar gold electrode was studied by cyclic voltammetry (CV). The electron transfer of through the MPA SAMs and Cu underpotential deposition (UPD) on MPA-covered electrode indicated that MPA molecules assemblied on the planar gold electrode could form a very compact layer, which could surpass the electron transfer K₃Fe(CN)₆ greatly, whereas on the surface on the nanogold, which curvature make the compact packing loose. The reductive desorption in 0.5 M KOH and oxidative desorption in phosphate buffer solution (PBS) (pH 6.8) showed that gold nanoparticles could enhance the Au-S bond and stabilize the MPA molecules.