对毛细管电动力学色谱中t0和tmc测定方法的考察

在同系物方法测定胶束迁移速度（ｌ／ｔｍ ｃ ） 的基础上提出了一种同时求算电渗流速率（ｌ／ｔ０） 的ｔ０ 和ｔｍ ｃ 的新方法， 该法在选择同系物标记物较为适当时， 可以得到更为准确的结果。同时可以减少由ｔ０ 测定而带来的误差。 实验结果表明， 采用甲醇等标记物测定电渗流速率时， 由于其在胶束中的溶解使得实测结果较真值偏大，而由此计算得到的ｔｍ ｃ 值偏低。ｔ０ 、ｔｍ ｃ 皆与缓冲液的种类和浓度有关， 这可能是由于缓冲液组成的变化不仅使得离子强度改变， 也使柱管壁和胶束表面的ξ势发生变化所致。同系物标记物的选择对ｔ０ 、ｔｍｃ 测定精度影响的讨论也为实际分析系统ｔ０ 、ｔｍｃ 的测定和分析分离条件的优化选择提供了必要的理论依据。     

Photoluminescent,liquid‐crystalline,and electrochemical properties of para‐phenylene‐based alternating conjugated copolymers

Novel liquid‐crystalline alternating conjugated copolymers [ P(P(6)CN‐alt‐Cz) and P(P(6)CN‐alt‐MeP) ] with phenylene and carbazolylene or phenylene with methyl substitution onto the main chain have been synthesized through palladium‐catalyzed Suzuki coupling reactions. The influence of the incorporation of carbazolylene and the substituted phenylene into the main chain on the thermal, mesomorphic, and luminescent properties has been investigated by Fourier transform infrared spectroscopy, thermogravimetry, differential scanning calorimetry, polarized optical microscopy, ultraviolet–visible spectroscopy, photoluminescence (PL), and cyclic voltammetry. These polymers show highly thermal stability, losing little of their weights when heated to 360 °C. The conjugated copolymers exhibit liquid crystallinity at elevated temperature. The existence of the chromophoric terphenyl core endows the copolymers with high PL and the polymer P(P(6)CN‐alt‐Cz containing carbazolylene unit can emit more pure blue light. All the copolymer films with low band gaps about 2.3–2.4 eV undergo reversible oxidation and reduction processes, significantly lower than the band gap of poly(p‐phenylene). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 434–442, 2010     

Thermal effect mechanism of magnetoresistance p-type diamond films

Based on the analysis and the discussion of the influence of thermal ionization energy and various scatterings on magnetoresistance（MR） of p-type diamond films, a revised model of valence band split-off over temperature is put forward, and a corresponding calculation formula is given for the MR of p-type diamond films （Corbino discs）. It is shown that the theoretical calculation that the MR of diamond films changes with temperature is consistent with the experiment. The influence of Fermi energy level on MR of diamond films is discussed. Additionally, the thermal effect mechanism of MR in p-type diamond films is also explored.     

Preparative enrichment and separation of astragalosides from Radix Astragali extracts using macroporous resins

The enrichment and separation of astragalosides I–IV (AGs I–IV) were studied on eight macroporous resins in the present study. SA‐3 resin offered the best adsorption and desorption capacities for AGs I–IV than other resins. The models of adsorption kinetics were investigated in order to elucidate the mechanism of adsorption. The pseudo‐second‐order model was the better choice than the pseudo‐first‐order model to describe the adsorption behavior of AGs I–IV onto SA‐3 resin. The equilibrium experimental data were well fitted to Langmuir and Freundlich isotherms. SA‐3 resin adsorption chromatography tests were carried out to optimize the separation process of AGs I–IV from Radix Astragali extracts. With the optimum parameters for adsorption and desorption, the contents of AGs I–IV were 8.78‐, 11.60‐, 10.52‐ and 11.28‐fold increased with the recovery yields being 65.88, 90.92, 84.25 and 94.17%, respectively. The preparative enrichment and separation of AGs I–IV from Radix Astragali extracts can be easily and effectively achieved by SA‐3 resin adsorption chromatography. The developed methodology can also be referenced for the separation of other active constituents from herbal materials and manufacture of Radix Astragali products.     

Weak acid leaching of uranium ore from a high carbonate uranium deposit

Journal of Radioanalytical and Nuclear Chemistry - Mineralogical study showed that the Yuejin uranium ore is from a low grade, high carbonate and high pyrite sandstone type uranium deposit. Uranium...     

基于XML的故障诊断虚拟训练描述模型研究

随着科学技术的迅猛发展,传统故障诊断训练存在的问题日益突出,越来越难以满足维修人员的故障诊断训练需求。提出了通过虚拟方式进行辅助训练,来提高维修人员的故障诊断能力和掌握故障诊断相关知识,满足故障诊断训练需求。为实现故障诊断虚拟训练,分析了故障诊断虚拟训练模型的描述要素和描述语言。运用诊断树分析方法,基于XML建立了故障诊断虚拟训练描述模型,为实现故障诊断虚拟训练提供模型支撑。最后,基于此模型对液压千斤顶回收不到位的故障进行了描述,验证了描述模型的正确性与实用性。     

First-principles study of structure and nonlinear optical properties of CdHg(SCN)4 crystal

The geometric structure,electronic structure,and optical properties of CdHg(SCN)4 crystal are calculated by using the density functional perturbation theory and Green function screening Coulomb interaction approximation.The band gap of CdHg(SCN)4 crystal is calculated to be 3.198 eV,which is in good agreement with the experimental value 3.265 eV.The calculated second-order nonlinear optical coefficients are d_(14) = 1.2906 pm/V and d_(15) = 5.0928 pm/V,which are in agreement with the experimental results(d_(14)=(1.4 ±0.6) pm/V and d_(15)=(6.0 ±0.9) pm/V).Moreover,it is found that the contribution to the valence band mainly comes from Cd-4d,Hg-5d states,and the contributions to the valence band top and the conduction band bottom predominantly come from C-2p,N-2p,and S-3p states.The second-order nonlinear optical effect of CdHg(SCN)_4 crystal results mainly from the internal electronic transition of(SCN)~-.     

A statistical model of microcracking of concrete under uniaxial compression

At increasing external load, numerous microcracks propagate in discrete and successive stages within a body of concrete material according to the hierarchy of their tensile fracture strengths. Each microcrack propagation is conditional upon the statistical encounter of its associated fracture criterion. This paper shows the development of a statistical model for the progressive microcrack growth process within a body of concrete material at monotonic uniaxial loading in compression to ultimate failure. This model is formulated by using the Weibull's statistical theory of the strength of materials. The body of heterogeneous concrete material is simulated as a continuum comprising a large population of microscopic “weakest-link” isoenergy elements, each of which contains a unit-volume of representative micro-structural material which is linearly elastic, homogeneous and isotropic. The statistical modelling is derived from the stochastic evaluation of the tensile micro-fracture probabilities of these isoenergy elements at increasing global uniaxial compressive strains.