New composite grouting materials: Modified urea–formaldehyde resin with cement

A new composite two component grout comprised of modified urea–formaldehyde resin and cement was formulated to take account of the advantages and disadvantages of both the cement grout and the chemical grout. The new grout is designed for water blocking by reinforcing as well as seepage control by bore grouting. The A component consists of a modified urea–formaldehyde resin A component, some cement, and some water. The B component is an alkaline coagulant. An orthogonal test of four factors at three levels showed that gel time increased with increased water content and with urea–formaldehyde resin content. Gel time decreased at increased levels of alkaline coagulant. The A component of this new composite grout is stable over time. A mixed cross-over test showed that as the volume ratio of A to B increases the gel time falls at first but then increases. The solid strength decreases with increasing levels of the B component. The solid strength increases over time and becomes stable by the 28th day after mixing. The viscosity increases with increasing levels of resin A component. The increase is exponential and may be fit to: μ = 8.162e^0.0286x.     

在离子液体介质中壳聚糖席夫碱衍生物的合成与表征

以水杨醛(SA)为改性试剂,在离子液体1-丁基-3-甲基咪唑氯盐(BmimCl)介质中对壳聚糖(CS)进行了席夫碱化改性研究.考察了反应条件(反应物摩尔比、反应温度和反应时间)对产物取代度的影响,得到的最佳反应条件为:0.15 g壳聚糖溶解于10 g BmimCl中,壳聚糖中氨基与水杨醛摩尔比为1∶2.5,反应温度为80℃,反应时间为2 h.在最佳反应条件下,壳聚糖水杨醛席夫碱衍生物的取代度可达29.2%.利用红外、核磁及XRD等表征技术对产物进行了表征,并在最佳试验条件下合成了系列壳聚糖席夫碱衍生物.     

溶剂萃取分离S-(+)-DMCPA酶法制备液中底物和产物的研究

采用分步溶剂萃取法对脂肪酶Novozyme 435催化2,2-二甲基环丙烷甲酸乙酯(DMCPE)不对称水解得到的S-(+)-2,2-二甲基环丙烷甲酸(S-(+)-DMCPA)制备液进行萃取分离.结果表明,采用等体积正己烷为萃取剂,在35℃和200r/min下,对酶法制备液萃取3次,每次萃取40min,底物DMCPE的萃取收率可达99.2%;继而采用等体积的乙酸乙酯在30℃,200r/min条件下,对萃余液进行2次萃取,每次萃取30min,产物S-(+)-DMCPA的萃取收率为99.5%.该研究对从酶法制备液中实现产物S-(+)-DMCPA的分离和未转化底物DMCPE的回收再利用,以及今后该分离过程的放大具有一定的借鉴和指导意义.     

浅谈基础教育阶段的创新教育工作开展

在知识经济的时代背景下,在建设创新型国家的要求下,创新意识必将成为公民的基本素质。培养创新型人才则是时代赋予学校教育的重要历史使命。本文在深入调研的基础上,结合实际情况,综合论述在基础教育阶段,创新教育的内涵、定位和实施情况。     

基于连续渗流的WSN非规则通信模型

在连续渗流理论基础上提出一种新的非规则通信模型,减小邻居节点的半径,实现网络稀疏性,通过随机加长某些拓扑边提高网络连通性,解决两者之间的矛盾。仿真实验结果表明,该通信模型在稀疏性和连通性方面均优于UDG通信模型,减少节点能耗,延长网络的生命周期。     

Electrochemical and spectroscopic characteristics of copolymers electrochemically synthesized from 3-(4-fluorophenyl)thiophene and 3,4-ethylenedioxythiophene

The copolymerization of 3-(4-fluorophenyl)thiophene (FPT) and 3,4-ethylenedioxythiophene (EDOT) was successfully achieved electrochemically in acetonitrile containing 0.1 M tetrabutylammonium tetrafluoroborate as supporting electrolyte by direct anodic oxidation of the monomer mixtures on platinum or stainless steel electrodes. As-formed copolymer own both the advantages of poly(3-(4-fluorophenyl)thiophene) (PFPT) and poly(3,4-ethylenedioxythiophene) (PEDOT), such as good electrochemical behaviors, high conductivity and excellent ambient stability. The structure and morphology of the copolymer were investigated by UV-vis, infrared spectroscopy, thermal analysis and scanning electron microscopy (SEM), respectively.     

The effects of oxygen partial pressure on the acoustic velocity in zirconia films studied by picosecond ultrasonics

We have performed a picosecond ultrasonic study of the effects of oxygen partial pressure on the acoustic velocity in zirconium oxide films made by radio frequency reactive sputtering. To derive more accurate and reliable values of sound velocity, various reflective layers were used to enhance the echo signals of acoustic pulses photoexcited by an ultrafast laser. It is found that the acoustic responses of the samples with a W reflective layer are much stronger than those with a Si or SiO₂ reflective layer. In addition, the W reflective layer generates extra photoacoustic waves, which can be utilized to improve the accuracy of velocity measurement. The thin film velocities we measured were 10∼24% less than the bulk value, and exhibited a strong dependence on the growth conditions and the microstructure of films.     

基于MSC Nastran的机翼振动抑制技术研究

利用MSC Nastran开发语言DMAP(Direct Matrix Abstraction Program),基于现代控制理论,建立机翼有限元结构的振动控制模型,并使用线性二次型最优控制理论对机翼结构进行振动抑制研究. 根据MSC Nastran对于大型稀疏矩阵强大的求解功能,有效地实现主动控制方法在大型有限元结构上的应用,并取得很好的控制效果.     

掺镧钛酸铅铁电薄膜的电畴与热释电性能研究

采用射频磁控溅射技术在Pt/Ti/SiO2/Si(100)基底上生长了掺镧钛酸铅[(Pb0.9La0.1)TiO3, PLT10]铁电薄膜.用X射线衍射研究了PLT10薄膜的结晶相结构.分别使用原子力显微镜和压电响应力显微镜观察了PLT10铁电薄膜的表面形貌和对应区域的电畴结构.测试了PLT10铁电薄膜的电学参数,研究了PLT10铁电薄膜的制备条件与其性能之间的关系.发现在优化条件下制备的PLT10铁电薄膜的介电常数εr为365,介电损耗tgδ为0.02,热释电系数γ为2.20×10-8C·(cm2·K)-1,可以满足制备非制冷红外探测器的需要.     

基于GIS的城市管网管理系统的设计与实现

本文介绍了采用MapX开发城市管网信息系统的具体过程,并对系统的设计原则、结构设计及功能设计等方面的内容进行了深入分析;为城市规划及管理部门提供了科学管理、科学建设城市的决策依据。