A new, nickel‐coated graphite resistance‐change‐based method for gel‐point determination for epoxy‐based thermoset resins is presented and compared with DSC and rheological methods. Gelation times determined by this new method are in very good agreement with conventional techniques; this new method is potentially simpler and less time consuming than existing ones.
Hydro(solvo)thermal reactions of Cu(NO3)2·2.5H2O or Zn(NO3)2·6H2O with 1,3-H2bdc provided two structurally different coordination polymers; a 2D network “metallacalixarene” based on the paddlewheel-type cluster with the formula [Cu(1,3-bdc)·H2O]·H2O (1) and a 3D framework [Zn(1,3-bdc)] (2), respectively. The use of a base was unnecessary in this synthesis; however, the presence of benzene played a crucial role in the crystallization of the desired products and could act as a template molecule in the synthesis of polymer (1). The unsaturated apical sites in the Cu2 cluster of polymer (1) were occupied by water molecules, what consequently led to the structural decomposition of the framework after exposing the sample in air, which was not the case of the Zn-coordination polymer (2). 相似文献
Multiple sequence alignment (MSA) and phylogenetic tree reconstruction are one of the most important problems in the computational biology. While both these problems are of great practical significance, in most cases they are very computationally demanding. In this paper we propose a new approach to the MSA problem which simultaneously infers an underlying phylogenetic tree. To process large data sets we provide parallel implementation of our method, which is based on the distributed caching of intermediate results. Finally, we show a parallel server designed for grid environments, and we report results of experiments performed with actual biological data, e.g. 1000 ribosomal RNA sequences. 相似文献
Unsupported intermetallic phases of palladium and lead, formed by reduction possess attractive catalytic properties for selective hydrogenation. The significance of the ease of reduction of divalent lead in Lindlar (supported) catalysts is also discussed.We thank the Science and Engineering Research Council for supporting this work. 相似文献
对薄板的高阶振动进行了讨论。应用模型基于Kirchhoff平板理论的假定和公差平均值的假定[Wo■ niak Cz,Wierzbicki E.Averaging techniques in thermomechanics of composite solids.Tolerance averaging versus homogenization.Poland,Czestochowa:Czestochowa University of Technology;2000],这使得模型可以考虑到周期单元对于整块板性能的影响。假设对周期单元振动的影响参数过多,可以对模型进行比基本振型更高阶的振动分析。这些函数是通过从边界条件中分离周期单元,对其自振时的特征值方程分析选取的近似值[JedrysiakJ.On vibrations of thin plates with one-dimensional periodic structure.Int J Eng Sci 2000;38:2023-2043]。通过应用平面板模型-正交各向异性模型、有限元模型和离散模型,对提议模型进行了论证。 相似文献