抗药性基因克隆技术研究进展

综述了近几年来抗药性基因克隆技术的研究进展。对RAPD-PCR、单链构象多态性(SSCP)、差异显示PCR(DDRT-PCR)、代表性差异分析技术(representational difference analysis，RDA)、抑制消减杂交法(suppression subtractive hybridization，SSH)、获得全长基因的消减杂交法(full length gene obtainable subtractive hybridization)、基因芯片技术、基因表达系统分析(serial analysis of gene expression，SAGE)的技术和从蛋白质水平克隆抗药性基因的双向电泳技术(two-dimensional gel electrophoresis)、噬菌体表面全套抗体库技术(phage display antibody repertoire library technique)、核糖体展示抗体库技术等方法的特点、优缺点及适用性进行了评述。     

一种适于异构环境的任务调度算法

针对异构环境独立任务调度问题提出两个调度原则,并基于Min-min算法提出优先级最小最早完成时间算法(Priority min-min,PMM).该算法将任务在各处理机上执行时间的标准误差作为任务的优先级.选取最早完成时间较小的k个任务,优先调度其中优先级最高的一个.在实验基础上分析了参数$k$对PMM算法性能的影响. PMM算法克服了min-min算法单纯追求局部最优的局限性,更适合于异构环境.实验数据表明PMM算法能有效地降低调度跨度,其性能比min-min算法有明显提高.     

宽带平坦型软X射线多层反射膜的设计

提出一种宽带平坦型软X射线多层反射膜的设计方法。给出了18nm 20nm波段的设计结果,整个波段的反射率与25%的最大偏差小于1.5%.这种方法对于软X射线波段的成像、光谱分析等应用有重要意义。     

脂肪醇气相色谱保留值的拓扑指数法

定量结构-色谱保留指数相关性(QSRR)方法已成为色谱领域中的有用工具,用于解释与预测各种物质的色谱行为。计算了35种脂肪醇的两类拓扑指数值,其一是基于原子类型特征的电性拓扑状态指数(En),其二是自分子拓扑图的邻接矩阵衍生的分子连接性指数(MCI)。这些拓扑指数被用于关联25种脂肪醇的色谱保留指数,经向后逐步回归与偏最小二乘法,建立了7个RIk与1Xvp,E5的最佳方程。它们的相关系数均在0.994以上,平均估算误差接近实验误差,并通过Jackknife的逐一剔除法证明有良好的可靠性与稳定性。结果表明,这些模型能够解释脂肪醇气相色谱保留指数的递变规律。     

Preparation and characterization of coke resistant Ni/SiO2 catalyst for carbon dioxide reforming of methane

Silica supported Ni catalyst is highly active for the CO₂ reforming of methane but it has poor stability due to coke formation. In this work, a glow discharge plasma was applied for the decomposition of nickel nitrate on the SiO₂ support, followed by thermal calcination in air. The plasma treatment enhances the interactions between the Ni particles and the silica and significantly improves the Ni dispersion. The plasma-treated Ni/SiO₂ catalyst exhibits comparable activity to the Ni/SiO₂ catalyst prepared by the thermal method without plasma treatment. The coke resistance of the Ni/SiO₂ catalyst is significantly enhanced by the plasma treatment.     

聚合醇处理剂JLX作用机理研究

聚合醇ＪＬＸ是一种新型的泥浆处理剂,是协调钻井工程技术和环境保护之间矛盾的产物。现场应用表明：聚合醇具有优异的防塌,润滑和保护油气层等特性。本文通过实验对聚合的作用机理进行研究：（１）聚合醇为一非离子型低分子聚合物,具有浊点效应。     

A segregation model study of suspension-based additive manufacturing

The additive manufacturing method of direct ceramic stereolithography directly fabricate complex core and shell molds while suspensions of coarser or denser particles have undergone differential sedimentation and cause particle size segregation. In order to safely use refractory coarse ceramic powder without the segregation problem, we develop a segregation model derived from the degree of segregation parameter (β) with the relation of two time constants; the writing time and the settling time. Given the relationships of material, apparatus, and design parameters, no segregation is expected in the silica particle dispersed suspension with average particle size of 40?μm when laser powers larger than 89?mW or 60?mW is applied to build layers with layer thicknesses of 150?μm or 250 μm, respectively. The explanation and application of the segregation model provided in this article enables to easily determine optimum variables and maximize the efficiency of additive manufacturing methods, thus able to suppress segregation in a layer.     

Temperature-programmed Studies of Coke Resistant Ni Catalyst for Carbon Dioxide Reforming of Methane

Argon glow discharge plasma was applied for drying the impregnated Ni/SiO₂ catalyst instead of the drying thermally. Such plasma treated catalyst significantly inhibits the coke formation from methane decomposition. The methane-derived carbon shows an improved reactivity against CO₂. This can result in a better balance of coke formation and gasification by CO₂ when the plasma-treated Ni/SiO₂ catalyst is used for the CO₂ reforming of methane.     

Enhanced Activity of Bimetallic Pd-Based Catalysts for Methane Combustion

In this work, the bimetallic Pd catalysts containing Ag, Cu, Co and Ni were prepared via the glow discharge plasma treatment followed by calcination thermally. The X-ray photoelectron spectroscopy (XPS) analysis confirms that the plasma treatment can reduce Pd²⁺ effectively. The calcination of the plasma formed Pd clusters enhances the formation of PdO that was identified as the active species for methane combustion. Compared to the conventional catalysts, all the plasma prepared samples show an enhancement in the activity at the same temperature. Among the investigated catalysts, the Pd–Ag/HZSM-5 sample exhibits the best activity for methane combustion.     

DQEM for large deformation analysis of structures with discontinuity conditions and initial displacements

A nonlinear mathematical model of the large deformation analysis of beams with discontinuity conditions and initial displacements is first formulized by the arc coordinates. The differential quadrature element method (DQEM) is applied to discretize the nonlinear mathematical model, and an effective method of applying DQEM to analyse the large deformation of structures with discontinuity conditions of multivariables is presented. A set of DQEM discretization equations are obtained. Then, the Newton–Raphson method is used to solve the system of nonlinear algebraic equations. As applications, some numerical examples in engineering are presented, which include the large deformation analysis of beams, frames, piles with elastic joints. The obtained results are compared with those in the existing literatures. The numerical results show that the model and the method presented in this paper may be widely applied to solve the problems of large deformation of structures with discontinuity conditions in engineering; also the method has the advantages of little amount in computation, good stability and convergence and so on.