Modeling the mechanical behavior of metal-reinforced plastic pipes under internal pressure

Numerical nonlinear models for the mechanical behavior of the metal-reinforced plastic pipes (MRP) in destructive tests are developed to analyze the stress-strain state (SSS) in such pipes during loading. The influence of contact conditions at the polyethylene-steel boundary on the SSS of the metal-reinforced plastic pipes at normal temperatures is considered. A criterion of ultimate state of MRP is suggested to predict the load-carrying capacity of the pipes under internal pressure. The behavior of a welded butt joint of the MRP is studied, a stress redistribution phenomenon in the reinforcing skeleton is revealed, and the results obtained in destructive tests of butt joints are explained.Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 1, pp. 57–70, January–February, 2005.     

Synthesis and characterization of oligocyclosiloxanes via the hydrosilation of vinylsilanes and vinylsiloxanes with heptamethylcyclotetrasiloxane

The preparation of oligocyclosiloxanes via hydrosilation reactions has been investigated. Hydrosilation reactions employing heptamethylcyclotetrasiloxane and vinyl-containing silanes and siloxanes yielded a variety of oligocyclosiloxanes with various numbers of cyclosiloxane rings connected through tri-, tetra-, penta-, hexa-, hepta-, or octafunctional junctions. The oligocyclosiloxanes were characterized by gas chromatography, IR spectroscopy, ²⁹Si-, ¹H-, and ¹³C-NMR spectroscopy, elemental analysis, and vapor phase osmometry. The polycyclics were redistributed with hexamethyldisiloxane and the resulting fragments analyzed by gas chromatography. All results were consistent with the formation of isomeric oligocyclosiloxanes due to a lack of absolute regioselectivity of the hydrosilation reaction. © 1993 John Wiley & Sons, Inc.     

甲基乙烯基硅酮在外场作用下的光激发特性研究

采用密度泛函B3P86和组态相互作用方法在6-311++G^**基组水平上计算了甲基乙烯基硅酮分子从基态到前10个激发态的跃迁波长，振子强度，自发辐射系数A_n0和吸收系数B_0n(n＝1—10).同时研究了外电场对甲基乙烯基硅酮分子激发态的影响规律.结果表明，随外电场强度增大，最高占据轨道与最低空轨道能隙变小，激发能随电场增加而急剧减小.因而表明在外电场作用下，分子易于激发和 关键词： 甲基乙烯基硅酮 激发态 外电场     

考虑节点综合重要度的物流网络级联失效模型

为提高突发事件级联失效对物流网络破坏程度的评估的可信性,提出一个考虑物流网络边权特征的节点重要度的综合度量方法,并在此基础上构建相应的级联失效模型。数值仿真结果表明：该模型对于物流节点重要度的衡量更为完善,所制定的失效负载分流准则及其对于级联失效破坏性的评估结果更具合理性。通过该模型可更加全面地掌握了解网络结构对于级联失效破坏的抵御能力,为物流应急管理提供理论支持。     

Preparation and characterization of polyurethan‐block‐poly(trifluoro‐ propylmethyl)siloxane elastomers

A series of polyurethane‐block‐poly(trifluoropropylmethyl)siloxane (PUFS) elastomers were prepared via a two‐step process from toluenediisocyanate (TDI), α ω‐bis(3‐aminopropyldiethoxylsilane) poly(trifluoropropylmethyl)siloxane (APFS), and poly(tetramethylene oxide) (PTMO). The PUFS films were formed through moisture curing and characterized by DSC, DMTA, TGA, mechanical testing, and water contact angle. It was found that the extent of microphase separation of the PUFS system would increase with the increase in APFS content, and result in the decrease in the tensile strength and the thermal stability. On the other hand, the crosslink density of the PUFS system would apparently increase with the increase in the TDI content, which reduced the microphase separation and improved the tensile properties and the thermal stability of the PUFS elastomers. Copyright © 2009 John Wiley & Sons, Ltd.     

HArF和HNO二聚体相互作用氢键的理论研究

The hydrogen bonding interaction of 1:1 dimer formed between HNO and HArF molecule has been completely investigated in the present study using Second-order M?ller-Plesset Perturbation (MP2) method in conjunction with 6-311+G**, 6-311++G** and 6-311++G(2d,2p) basis sets. The standard and CP-corrected calculations have been employed to determine the equilibrium structures, the vibrational frequencies and interaction energies. The interaction energies of the dimers were also calculated at G2MP2 level. Two stable structures are found as the minima. Dimer I(H···F)is a five-membered cyclic hydrogen bonded structure and is more stable than the Dimer II(H···O). The blue-shifted N-H···F hydrogen bond is confirmed with standard and CP-corrected calculations by the MP2 and DFT methods in conjunction with different basis sets. The results obtained at MP2 in conjunction with different basis sets show there is a red-shifted hydrogen bond (Ar-H···O) in the Dimer II(H···O). The topological and electronic properties, the origin of red- and blue-shifted hydrogen bonds were investigated at MP2/6-311++G(2d,2p) with CP corrected calculations. From the NBO analysis, the reasonable explanations for the red- and blue-shifted hydrogen bonds were proposed.     

Crystal and Molecular Structure of N‐methyl‐N‐3‐(sulfonato)propyl‐3‐[tris(trimethylsiloxanyl)3‐silyl]pyrrolinium Sulfobetaine Hydrate at Room Temperature and 163 K

2 (C₁₇H₄₁NO₆SSi₄) . H₂O. M_r=1017.88, triclinic, space group P‐1. The molecules are arranged in bilayers. The molecules in each bilayer are held together by electrostatic forces, i.e., O‐N⁺ contacts, and hydrogen bonds. The asymmetric unit consists of two partly disordered siloxane molecules and one water molecule. The structure of the bilayers is virtually the same at 163 K and room temperature, but the stacking of the bilayers is different. The Si‐O‐Si bond angles at low temperature are significiantly smaller than at room temperature.     

Conformational analysis of siloxane-based enzyme-mimic precursors[1]

The conformational flexibility of six hybrid organodisiloxane oligomers were studied using the Low Mode-Monte Carlo conformational search method with the MM2* force field and the Generalized Born/Surface Area continuum solvent model for water. These systems have enzyme-like properties as synthetic acyltransferases and contain aminopyridine groups in various states of protonation. An ensemble of low energy structures was generated and used to investigate the dependence of molecular shape and flexibility on protonation, which plays an important role in catalyst solubility and self-association. The results as measured by the number of unique conformations, end-to-end or longest intramolecular distance and radius of gyration of the conformational point cloud indicate that the number of protonated pyridines plays a significant role in the overall molecular shape. A similar study was also carried out on various POSS-substitutive organodisiloxane oligomers.