The analysis of lubricating oil additives by supercritical fluid chromatography with packed and open tubular capillary columns

Lubricating oil additives have been analyzed by supercritical fluid chromatography on open tubular and packed capillary columns. Carbon dioxide and modified carbon dioxide were used as mobile phases and detection was accomplished by flame ionization and micro UV. Rapid and efficient analysis of the lubricating oil additives was demonstrated.     

A New Definition of the Stationary Phase Volume in Mixed-Mode Chromatographic Columns in Hydrophilic Liquid Chromatography

Polar columns used in the HILIC (Hydrophilic Interaction Liquid Chromatography) systems take up water from the mixed aqueous–organic mobile phases in excess of the water concentration in the bulk mobile phase. The adsorbed water forms a diffuse layer, which becomes a part of the HILIC stationary phase and plays dominant role in the retention of polar compounds. It is difficult to fix the exact boundary between the diffuse stationary and the bulk mobile phase, hence determining the column hold-up volume is subject to errors. Adopting a convention that presumes that the volume of the adsorbed water can be understood as the column stationary phase volume enables unambiguous determination of the volumes of the stationary and of the mobile phases in the column, which is necessary for obtaining thermodynamically correct chromatographic data in HILIC systems. The volume of the aqueous stationary phase, Vex, can be determined experimentally by frontal analysis combined with Karl Fischer titration method, yielding isotherms of water adsorbed on polar columns, which allow direct prediction of the effects of the composition of aqueous–organic mobile phase on the retention in HILIC systems, and more accurate determination of phase volumes in columns and consistent retention data for any mobile phase composition. The n phase volume ratios of 18 columns calculated according to the new phase convention strongly depend on the type of the polar column. Zwitterionic and TSK gel amide and amine columns show especially strong water adsorption.     

A simple procedure for evaluating the heterogeneity parameter and the ratio of molecular sizes of solute and solvent by using HPLC data

Based on the relationship defining the dependence of the capacity ratio upon the composition of the mobile phase, a simple numerical procedure is proposed for evaluating the heterogeneity parameter and the ratio of molecular sizes of solute and solvent. This procedure is examined by using HPLC data for pesticides chromatographed in isooctane/dichloromethane eluent on Lichrosorb at 291 K.     

Thermal aqueous liquid chromatography—the TALC technique

Thermal Aqueous Liquid Chromatography (TALC) using pure water as a mobile phase should be a very attractive technique promoting the use of liquid chromatography in routine analysis, either in the laboratory or in future on-line process control. This simple form of chromatography, the selectivity of which depends on the fixed phase only, would allow the use of flame ionization as an almost universal, low-cost detector in liquid chromatography. The potential of the TALC technique is illustrated by selected examples.     

Attempts to Exchange Iron into H-Y and H-ZSM-5 Zeolites by in situ Formed Chloride-Containing Mobile Species

Three variants of solid-state ion exchange were studied. Iron exchange was found to proceed in the first case, in theFeCl₂+NH₄ZSM-5 FeZSM-5 + NH₄Cl process, even at low exchange capacity (Si/Al = 25).The second, Fe₂O₃ (hematite) + HZ direct reaction does not result in any noticeable interaction for eitherZ = Y or ZSM-5. This process can significantly be promoted by introducing CCl₄ vapor via forming chlorine-containingmobile species. However, the structure of the Y zeolite largely collapses during this treatment, whereas the crystalline state of ZSM-5is preserved.     

Motion Planning for a Wheeled Robot (Kinematic Approximation)

The motion-planning problem for a wheeled robot is solved in kinematic approximation. The solution is given for robots with one and two steering wheels. The results of solving the problem for a specific system are compared with the results obtained by other authors__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 2, pp. 91–102, February 2005.     

复制受限的环境演算中模态逻辑的内涵性

环境演算(MA)的模态逻辑AL进行了研究．在考虑了复制操作和限制操作的情况下，提出了逻辑等价的协归纳操作描述，并利用协归纳关系与进程结构同余关系进行比较，证明了若对MA加上约束条件得到子集MAIF^syn，此时逻辑等价(=L)与结构同余关系是等价的，即AL在MAIF^syn中是内涵的．同时发现由于复制操作的存在，AL的内涵性受到了影响，使得AL的区分能力被削弱，但通过对复制公式的构造验证了AL的表达能力．     

高效液相色谱溶剂系统四面体优化法

改进了Ｇｌａｊｃｈ的三角形法,建立了适合于高效液相色谱（ＨＰＬＣ）的四面体优化法。将７个溶剂系统的实验结果输入计算机,由计算机模拟２３１个溶剂系统的色谱行为,优选出最佳溶剂系统。将此法用于１２种磺胺药物的分离,得到了满意的结果。     

基于移动Agent技术的医学图像检索方法

针对现有医学图像检索方法中，检索算法速度较慢、准确性较低以及远程检索时占用大量带宽等问题，设计并实现了一种基于移动Agent技术的医学图像检索方法，重点讨论了该方法实现的关键技术，包括提升框架下的M带整数小波变换和提取多通道纹理特征的检索算法．模拟实验结果表明，该方法实时性较强，占用网络带宽较少，采用的算法运算速度提高近10倍、运算复杂度降低约50％，提取的纹理特征能充分表达图像内容，较好地满足了医学图像的检索要求，实现了对医学图像库快速较准确的检索．