Four coordination polymers derived from 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole and copper sulfate

The reaction of 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-bpt) with copper sulfate in EtOH/H₂O solvent yields four coordination polymers [Cu(3-bpt)(H₂O)₄](SO₄)·H₂O (1), [Cu(3-bpt)(H₂O)₄][Cu(3-bpt)(H₂O)₃(SO₄)](SO₄)·7H₂O (2), [Cu(3-bpt)(H₂O)₃(SO₄)]·2H₂O (3) and [Cu(3-bpt)(H₂O)(SO₄)] (4), showing one-dimensional undulated chain, zigzag chain and two-dimensional network. The formations of compounds 1, 2 and 3 are controlled by the EtOH/H₂O ratio. The synthesis of compound 4 may be controlled by the EtOH/H₂O ratio and the temperature because it is prepared under solvothermal condition. The thermal properties have been investigated.     

Development on Technique of Tube Reducing in Double 3-Roll Dies

Based on the experiments, a new technique of reducing tube with two linked 3-roll roller dies was developed. The external friction conditions, velocity and the non-uniform deformation of metal were distinctly improved, and the friction between metal and tool was decreased. Corrosion strip layers and photo-elastic coatings methods were adopted in the experiment for measuring residual stress, and the residual stresses in the drawn tube with 3-roll dies are reduced.     

隧道下穿既有建筑物群沉降影响范围及影响程度分析方法浅析

隧道下穿建筑群时,必须对建筑可能产生影响进行预测及过程控制,目前主要的方法包括理论分析、数值计算、经验取值等。针对上述情况,分析了各方法的原理、适用性、优缺点。同时,以实际工程数据为依托,阐述了各种方法的具体应用,并进行相互验证,分析了各种分析方法的可靠性。提出目前隧道下穿建筑群影响范围的监控量测及综合应用的必要性。     

基于突变理论的土质边坡非线性演化分析

应用突变理论对土质边坡稳定性进行研究,从系统能量的角度出发,综合考虑边坡土体的成层性、应变软化特性和水致弱化性质而建立了尖点突变模型.突变分析表明,系统内部多重参数(如应变软化程度mi、含水量ξi、剪切刚度比ki、位移峰值强度ui)综合决定系统状态的控制变量a,b,并且内部参数受各外部激励因素的影响都是非线性的,边坡的孕育是一个复杂的非线性演化过程.同时,详细论述了3种典型边坡(稳定型边坡、外部因素持续作用下同步失稳的边坡和滞后失稳型边坡)的演化路径.     

Studies of the properties of a thermosetting epoxy modified with block copolymers

Poly[(n‐butyl acrylate)‐block‐poly(methyl methacrylate)‐co‐(glycidyl methacrylate)] (BMG) diblock copolymers incorporating an epoxy‐reactive functionality in one block have been synthesized and used as modifiers for the model epoxy resin E‐51 cured with 4,4′‐diaminodiphenyl methane (DDM). The properties and morphologies of the modified epoxy thermosets were investigated by dynamic mechanical analysis (DMA), impact testing and scanning electron microscopy (SEM). The results reveal that addition of the block copolymers leaves the glass transition temperatures of the blends relatively unchanged, with small decreases in the storage moduli at room temperature. The toughening effect is dependent on the chemical structures of the block copolymers and an increase in the impact strength by a factor of two was obtained by the addition of ‘relatively symmetrical’ block copolymers. Moreover, the impact test results are consistent with the morphologies of the fracture surfaces as evidenced by SEM. Copyright © 2005 Society of Chemical Industry     

Liquid dynamics and glass formation of Gd55Co20Al25 metallic glass with minor Si addition

Liquid dynamics plays an essential role in glass formation.Here we observed a distinct change of liquid dynamics in Gd55Co20Al25 metallic glass induced by microalloying Si element.In the equilibrium melt,minor Si(0.5 at.％)addition leads to a more fragile liquid behavior and a smaller strength of liquid-liquid transition with the transition strength(ΔF)decreasing from 0.76 to 0.35.However,in the supercooled liquid,Si-doped liquid exhibits a remarkable enhanced fragile-to-strong transition(FST),and the value of FST factor f increases sharply from 1.63 to 3.84,resulting in a stronger liquid behavior and more sluggish crystallization kinetics for Gd55Co20Al24.5Si0.5 metallic glass.Moreover,minor Si addition promotes the formation of a crystal-like structure with a size of 1-2 nm.The interactions between the crystal-like structures and other local favored clusters frustrate the further growth of crystal-like phases,thus sta-bilizes the amorphous structure.As a result,the glass-forming ability(GFA)was largely improved.The critical diameter of Gd55Co20Al25 metallic glass increased from 2 to 7 mm with 0.5 at.％Si addition with-out deterioration of the magnetocaloric effect.This study provides valuable insight for understanding the distinct effect of microalloying on GFA of metallic glasses from the aspect of the evolution of the liquid.     

大范围调整开关电源研究综述

本文介绍几种从零起词的大范围调整高压开关电源的结构形式、各自的特点，以及它们在工程上的应用实例。     

高放废液的玻璃固化及固化体的浸出行为与发展情况

对高放废液固化体的种类硼硅酸盐玻璃固化体的特点及结构进行了叙述，对玻璃固化体的浸出行为及其研究的发展情况进行概括，也谈及了我国在高放废注玻璃固化研究的状况。     

农村中职计算机应用基础教学三部曲

此文结合具体的教学实际,阐述提高农村中职学校计算机应用基础课教学效果的具体做法和体会。