New model of screening kinetics

An understanding of screening requires a knowledge of screening kinetics. The new model of screening kinetics presented in this paper is theoretically described and experimentally proven. Samples of different raw materials, different in their density, bulk density, particle size distribution and particle shape, were used.The conducted experiments confirmed that the new model of screening kinetics successfully describes the process of screening of various raw materials even when they are exposed to a range of factors that most influence the screening process (dimensions of the screen, particle size distribution of raw materials, particle shape, and thickness of the bed on the screen).The advantage of this model of screening kinetics lies in its simplicity as it is characterized by the fact that it has only one parameter, i.e., (k) - the screening rate constant, which is experimentally measured. This constant can be measured on the basis of a single screening experiment. This fact is very significant for practical applications of the model to an industrial screen.     

树脂塞孔空洞产生原因及改善对策

树脂塞孔工艺通常存在塞孔空洞及孔口凹陷的问题,对于POFV及叠层设计,孔口凹陷的存在会导致焊接面积变小,带来焊接可靠性的问题。文章分析了塞孔空洞的产生机理,通过实验验证,得出了产生塞孔空洞的主要影响因素,并针对性的给出了塞孔空洞的改善对策与建议。     

南瓜降血糖活性成分的筛选及初步鉴定

在被追踪的降血糖活性组分为未知的情况下,从南瓜中筛选出降血糖活性成分—南瓜多糖(PCEC),并对其作初步鉴定。借鉴祖国经典方剂的溶剂提取法,并在药理试验的配合下采用动物实验进行筛选,用成分分析及紫外扫描法对PCE-C进行鉴定。结果表明,小鼠经腹腔注射7h后就可以使其血糖值由(15.32±3.38)mmol/L降至正常范围(5.77±1.46)mmol/L;南瓜多糖主要由糖(69.82％)和蛋白质(17.53％)组成,UV吸收显示一个典型的糖吸收峰,而无核酸(260nm)和蛋白质(280nm)的特征吸收峰。从而筛选并初步鉴定出南瓜中的降血糖活性成分为多糖类物质。     

调频加网技术分析和研究

主要介绍调频加网技术的特点和网点产生的原理.通过对产生随机数的常用伪随机函数的分析和对比,选取乘同余伪随机函数为例,研究了调频加网技术的加网过程,探讨了调频网技术的应用前景.     

Optimal configuration design for plate heat exchangers

A screening method is presented for selecting optimal configurations for plate heat exchangers. The optimization problem is formulated as the minimization of the heat transfer area, subject to constraints on the number of channels, pressure drops, flow velocities and thermal effectiveness, as well as the exchanger thermal and hydraulic models. The configuration is defined by six parameters, which are as follows: number of channels, numbers of passes on each side, fluid locations, feed relative location and type of channel flow. The proposed method relies on a structured search procedure where the constraints are successively applied to eliminate infeasible and sub-optimal solutions. The method can be also used for enumerating the feasible region of the problem; thus any objective function can be used. Examples show that the screening method is able to successfully determine the set of optimal configurations with a very reduced number of exchanger evaluations. Approximately 5% of the pressure drop and velocity calculations and 1% of the thermal simulations are required when compared to an exhaustive enumeration procedure. An optimization example is presented with a detailed sensitivity analysis that illustrates the application and performance of the screening method.     

Meeting maximum residue limits: an improved screening technique for the rapid detection of antimicrobial residues in animal food products

A rapid, high-throughput antimicrobial screening assay was developed using either a physical fluid extraction or a solvent extraction technique coupled to the commercially available Premi®Test. The solvent extraction approach was fully validated for a wide range of tissues and the fluid extraction approach partially validated for porcine muscle. Both procedures can detect a wide range of antimicrobial compounds at or below maximum residue limit concentrations. The use of a solvent extraction provides an enhanced test capable of detecting a wider range of drugs than the fluid extraction approach at or below half maximum residue limit levels in a variety of matrices. Biochemical methods for the class-specific identification of β-lactams and sulphonamides following initial screening were developed and validated. The approach is a significant improvement on existing methodologies as a tool for residues monitoring in surveillance programmes.     

以热力学过程性质为目标的分子设计初探(Ⅱ)──目标分子构成基团的筛选与确定

以基团贡献原理为基础，建立了目标分子构成基团与热力学参数间的关系。以此关系为约束条件，在给定的基团样本空间中，用整数线性规划法确定了目标分子构成基团的个数，为进一步组合、设计目标分子打下了基础。     

振动香蕉筛在选煤厂的应用

香蕉筛是一种应用于大物料量的筛选处理的新型振动筛，重点介绍了其理论特点，发展过程、高效率和在选煤厂应用效果，它是传统倾斜式水平筛的理想替代振动筛，是今后振动筛的发展方向。     

Multi-criteria shape optimization of a funnel in cathode ray tubes using a response surface model

One purpose of simulation describing the behaviors of structures is to optimize the performances within specific functional requirements and customers needs with respect to the design variables. For reduction of the volume of cathode ray tubes, the design of the glass geometry, especially funnel geometry, is essential while maintaining the internal vacuum pressure of the cathode ray tube. In order to describe the three-dimensional geometry of the funnel in cathode ray tubes, a higher-order response surface model is employed in the simulation model instead of non-uniform rational B-splines (NURBS) or Bezier curves because the response surface model is more robust for understanding the geometry change in finite element analysis. We formulate the design problem as a multi-criteria optimization because minimization of both volume and maximum stress is required. Using the response surface model of the geometry of the funnel and sequential quadratic programming within the process integration framework, the shape optimization of a funnel is successfully performed and the maximum stress level of the funnel is decreased by almost half.     

转基因作物筛查用阳性质粒分子的构建及应用研究

通过分析全球商业化种植的转基因作物分子特征,选取常用的调控元件启动子CaMV35S、FMV35S和nos,终止子NOS、T-35S、g73′和E93′,标记基因bar、NPTII、hptII、pmi作为筛查靶标序列,通过重组PCR技术将这些元件克隆到双元载体pBI121上,构建成包含11个转基因元件的通用阳性质粒分子pBI121-ELEMENTS。质粒序列信息已提交至GenBank并获得序列号HM047294。该质粒分子对目前国内外批准的5类主要转基因作物（大豆、油菜、玉米、棉花和水稻）理论筛查覆盖率达到91.5%,对我国批准进口的27种转基因作物的理论筛查覆盖率达100%。以pBI121-ELEMENTS为阳性对照,筛查7个转基因品系,结果显示该分子能够有效用于转基因作物定性筛查。