Thermosensitive hydrogels from copolymers of N-isopropylacrylamide and anionic monomers

Thermosensitive hydrogels containing anionic monomer have been prepared from copolymerization of N-isopropylacrylamide and 3-sulphopropylacrylate potassium salt, 3-sulphopropylmethacrylate potassium salt and 2-acrylamido-2-methyl-1-propanesulphonic acid in the presence of N,N′-methylene-bisacrylamide as crosslinking agent with potassium persulphate/N,N,N′,N′,-tetramethylethylenediamine as initiator in water at room temperature. The swelling behaviour and volume transition temperature of the gels containing different anionic monomers were studied. It was found that with increasing content of anionic monomer, the swelling ratio as well as the volume transition temperature of the gel increased. The swelling behaviour of the gels in salt-containing water was investigated.     

DK5型低压真空断路器的试验分析与探索

对DK5型低压真空断路器的摸底试验和型式试验进行详细的总结与分析,从而探求提高开关性能指标的更佳方案.     

基于移动平台的自动测试系统

本文首先阐述了网络化测控仪器的产生背景,分析了传统的自动测试系统的不足之处。针对传统的缺陷设计了新型的自动测试系统。介绍了在网络化测量中的基于无线移动平台的网络接入技术,提出了使用嵌入式控制系统的无线网络接入方案,给出了基于GPRS的自动测试系统架构图及其软件的组成与性能。设计制作了网络接入的协议转换装置。编写了网络通路建立软件。新系统在一定程度上解决了自动测试系统的灵活性难题,很好地解决多种工业总线的系统集成问题,大大丰富了工业总线的体系。     

电调衰减器的自动测量法

文中介绍了电调衰减器的自动测量方法。通过上位机程序对功率计及接口电路的控制,可自动测得电调衰减器一系列衰减量对应的控制码。该方法提高了测量结果的准确性,并缩短了测量所需时间。     

Vortical structures and wakes of a sphere in homogeneous and density stratified fluid

Vortical structures and wakes of bluff bodies in homogenous and stratified environment are common and important in ocean engineering.Based on the Boussinesq app...     

The grain-boundary resistance of CeO2 ceramics: A combined microscopy-spectroscopy-simulation study of a dilute solution

Weakly acceptor-doped ceria ceramics were characterized structurally and compositionally with advanced transmission electron microscopy (TEM) techniques and electrically with electrochemical impedance spectroscopy (EIS). The grain boundaries studied with TEM were found to be free of second phases. The impedance spectra, acquired in the range 703 ≤ T/K ≤ 893 in air, showed several arcs that were analyzed in terms of bulk, grain-boundary, and electrode responses. We ascribed the grain-boundary resistance to the presence of space-charge layers. Continuum-level simulations were used to calculate charge-carrier distributions (of acceptor cations, oxygen vacancies, and electrons) in these space-charge layers. The acceptor cations were assumed to be mobile at high (sintering) temperatures but immobile at the temperatures of the EIS measurements. Space-charge formation was assumed to be driven by the segregation of oxygen vacancies to the grain-boundary core. Comparisons of data from the simulations and from the EIS measurements yielded space-charge potentials and the segregation energy of vacancies to the grain-boundary core. The space-charge potentials from the simulations are compared with values obtained by applying the standard, analytical (Mott–Schottky and Gouy–Chapman) expressions. The importance of modelling space-charge layers from the thermodynamic level is demonstrated.     

Defect chemistry of A site nonstoichiometry and the resulting dielectric behaviors in SrxTi0.985(Nb2/3Zn1/3)0.015O3 ceramics

Defect chemistry of Sr site nonstoichiometry in Sr_xTi_0.985(Nb_2/3Zn_1/3)_0.015O₃ ceramics and the resulting effects on the structure and dielectric behavior are systematically investigated by experiment and density functional theory (DFT) methods. The results indicate that, appropriate Sr deficiency benefits the dielectric properties and grain growth due to the creation of Sr vacancy. While Sr excess deteriorates the dielectric properties and inhibits the grain growth by forming a Ruddlesden-Popper structure. In Sr-deficient sample, more point defects arise and aggregate into defect clusters, resulting in great changes in local structures and the enhancement of dielectric properties. The Sr vacancy benefits the generation of oxygen vacancy, thus facilitating the localization of electrons and the decrease in dielectric loss. Besides, the electronic polarization and structural polarization are also improved by Sr vacancy and the resultant oxygen vacancy, leading to the further enhanced dielectric properties. These findings may facilitate the development of defect engineering towards novel multifunctional electronic materials.     

工程机械4WS电液控制系统试验装置的工作原理

简要分析了4轮转向试验平台的工作原理,其中包括加载系统、气动振动系统、转向系统和电器控制系统的工作原理。并对其可行性进行了分析。     

An investigation into the antiwear,antioxidation, and anticorrosion behaviour of some derivatives of 2,5-dimercapto -1,3,4-thiadiaxole

It appears that the comprehensive performance of 2,5-dimercapto-1,3,4-thiadiazole derivatives is dependent upon both the type and the structure of the chains attached to the carbon atoms in the 2 and 5 positions of the thiadiazole ring. For the side chain of the monosulphide type R-S-, the type and location of substituents have an important influence on additive performance. In the case of the side chain of the disulphide type, X-SS-, the presence of the phosphorus-containing group has a significant effect on multifunctionality.