Nucleotide variation in the triosephosphate isomerase (Tpi) locus of Drosophila melanogaster and Drosophila simulans

DNA sequence variation in a 1.1-kb region including the coding portion of the Tpi locus was examined in 25 homozygous third-chromosome lines of Drosophila melanogaster, nine lines of Drosophila simulans, and one line of Drosophila yakuba. Our data show that the widespread allozyme polymorphism observed in cosmopolitan D. melanogaster is due to a glutamic acid substitution occurring in a phylogenetically conserved lysine that has been identified as part of the "hinged-lid" active site of the enzyme. This observation suggests that the replacement polymorphism may have important functional consequences. One replacement polymorphism was also observed in D. simulans, although its functional relevance is more difficult to assess, since it affects a site that is not strongly conserved. This amino acid change in D. simulans is associated with a single lineage possessing seven unique silent substitutions, which may be indicative of balancing selection or population subdivision. The absence of fixed amino acid differences between D. melanogaster and D. simulans and only a single difference with D. yakuba suggests that triose phosphate isomerase is under strong functional constraint. Silent variation is slightly higher for D. melanogaster than for D. simulans. Finally, we outline the general lack of evidence for old balanced polymorphisms at allozyme loci in D. melanogaster.     

FREE VIBRATION ANALYSIS OF KIRCHHOFF PLATES RESTING ON ELASTIC FOUNDATION BY MIXED FINITE ELEMENT FORMULATION BASED ON GÂTEAUX DIFFERENTIAL

The main objective of the present work is to give the systematic way for derivation of Kirchhoff plate-elastic foundation interaction by mixed-type formulation using the Gâteaux differential instead of well-known variational principles of Hellinger–Reissner and Hu–Washizu. Foundation is a Pasternak foundation, and as a special case if shear layer is neglected, it converges to Winkler foundation in the formulation. Uniform variation of the thickness of the plate is also included into the mixed finite element formulation of the plate element PLTVE4 which is an isoparametric C⁰ class conforming element discretization. In the dynamic analysis, the problem reduces to solution of the standard eigenvalue problem and the mixed element is based upon a consistent mass matrix formulation. The element has four nodes and at each node transverse displacement two bending and one torsional moment is the basic unknowns. Proper geometric and dynamic boundary conditions corresponding to the plate and the foundation is given by the functional. Performance of the element for bending and free vibration analysis is verified with a good accuracy on the numerical examples and analytical solutions present in the literature. © 1997 by John Wiley & Sons, Ltd.     

磷块岩三轴压缩破坏特性与声发射规律的研究

采用应力加载系统和声发射测试系统,研究了三轴压缩试验中磷块岩裂纹破坏特性及声发射活动规律. 试验及分析研究表明:磷块岩三轴声发射加载全过程可分为裂隙压密阶段、弹性压缩阶段、裂纹初级扩展阶段、裂纹剧烈扩展阶段、宏观破坏阶段;磷块岩声发射事件在其强度最大阶段和宏观破坏阶段均有产生;磷块岩声发射事件数随着围压从2 MPa增加到4 MPa而减少.     

Paraffin treatment of garlic for long-term preservation

The optimal conditions have been developed for garlic preservation by its treatment with a mixture of food paraffin and monoglyceride in the ratio of 95:5 at 80 degrees C, followed by the storage at 0-1 degrees C, and relative humidity 65-75%. When garlic is treated with plasticized paraffin, the main hydrocarbon components of paraffin - n-alkanes C20-C31 are accumulated in its pulp. Monocyclic aromatic hydrocarbons are practically absent in food paraffin and paraffined garlic. The quantitative parameters of the paraffined garlic characterizing high technological and economic effectiveness of the method, as well as insignificant increase in the p-alkanes content (1%) in the daily ration for humans, that contains paraffined garlic, have permitted the authors to recommend this method of garlic storage for using under industrial conditions, the technological regulations should be strictly kept to.     

Investigation of the safety of the product "Rialam."

The data on safety investigation of product "Rialam", which is proposed as biologically active food supplement are presented. Chronic experiment and single generation experiment were made on Wistar rats. It is shown that diet "Rialam" in dose 100 mg/kg of body weight didn't influence negatively on growth and development of rats blood parameters, immune status, internal organs morphology, metabolism, hadn't embryotoxic, gonadotoxic and teratogenic action.     

1000MW二次再热火电机组管道热效率对系统热经济性的影响

以某1 000MW超超临界二次再热火电机组为研究对象,定量分析了系统管道的散热损失、厂用蒸汽系统损失及工质泄漏损失对单元机组热经济性的影响.结果表明:考虑全部损失时,管道热效率为97.394%,供电标准煤耗为271.935g/(kW·h).与无管道损失时相比,机组管道热效率降低2.606%,供电标准煤耗增加4.584g/(kW·h),说明在二次再热机组热经济性评价中应该考虑管道热效率.     

稀散元素铼的分析进展

铼属于贵重稀散金属元素,铼的分析方法发展较快。本文综述了近年来国内外铼的分析进展,包括了矿样的分解、铼的分离富集以及铼的测定。     

吐哈盆地侏罗系层序地层格架的建立

吐哈盆地是一个陆相含 油气盆地,侏罗系是主要的勘探目的层。运用层序地层学的理论和方法,通过对露头剖面、钻井和地震等资料的综合研究,可将侏罗系划分为七个层序(SQi-SQ>)。层序SQ.相当于八道湾组和三工河组,SQ2相当于西山窑组一二三段,SQ3相当于西山窑组四段和三间房组-段,SQ4相当于三间房组二三段,SQ3、SQ6和SQ,分别相当于七克台组、齐古组和喀拉扎组。煤系烃源岩主要分布于层序SQ1和SQ2的基准面上升半旋回的上部,储集层主要发育在层序SQ1SQ2、SQ3、SQ4和SQs上升半旋回,层序SQ3、SQ4SQs下降半旋回和SQ6SQz层序是区域盖层发育的主要层位。     

基于内部流场分析的小型轴流风扇结构优化

采用孤立叶型设计法、CFD技术、遗传算法等理论,运用自编软件对某一轴流风扇轮毂比参数进行结构优化设计,优化目标为风扇流量。对比分析优化前后风扇内部流场,如风扇的静特性、叶片表面静压分布、子午面涡量分布等信息。由此验证优化方法的可行性．,并总结轮毂比参数对此风扇性能的影响。结果表明：优化后风扇叶片和轮毂表面减小了因涡流带来的能量损失,但叶顶间隙处的涡流增大,能量损失略有增大;在不同流量下,优化后风扇静压有不同程度的提高;优化后风扇的出口速度均比优化前大幅提高;风扇在额定工况下性能、静特性及内部流场都得到了很好的改善。     

基于PLC的碱回收蒸发工段控制系统的设计

根据某造纸厂碱回收蒸发工段的工艺流程和控制要求,从系统硬件组态和软件设计两方面探讨了Simatic S7-300在碱回收蒸发过程中的应用;针对蒸发工段的出效浓黑液浓度难以控制的特点,提出了黑液浓度基于串级控制策略;利用WinCC组态软件实现上位机监控,模拟现场画面,显示所需监控的现场设备.经过运行表明,该系统调节准确,稳定了黑液浓度,降低了能耗,同时节约了设备投资.