Preparation and characterization of polyurethane microcapsules containing n‐octadecane with styrene‐maleic anhydride as a surfactant by interfacial polycondensation

A series of polyurethane microcapsules containing a phase change material (PCM) of n‐octadecane was successfully synthesized by an interfacial polymerization in aqueous styrene‐maleic anhydride (SMA) dispersion with diethylene triamine (DETA) as a chain extender reacting with toluene‐2,4‐diisocyanate (TDI). The average diameter of microPCMs is in the range of 5–10 μm under the stirring speed of 3000–4000 rpm. Optical and SEM morphologies of microPCMs had ensured that the shell was regularly fabricated with the influence of SMA. FTIR results confirmed that the shell material was polyurethane and the SMA chains associated on core material reacted with TDI forming a part of shell material. The shell thickness was decreasing in the range of 0.31–0.55 μm with the molar ratio of DETA/TDI from 0.84 to 1.35 and the weight of core material increasing from 40 to 80% (wt %). By controlling the weight ratio of PCM as 40, 50, 60, 70, and 80% in microPCMs, it was found using DSC that the T_m and T_c of microPCMs were in the range of 29.8–31.0^oC and 21.1–22.0°C and an obvious phase change had been achieved nearly the same temperature range of that of PCM. The results from release curves of microPCM samples prepared by 1.4, 1.7, and 2.0 g of SMA indicated the release properties were affected by the amount of the dispersant, which attributed to the emulsion effect and shell polymerization structure. The above results suggest that the shell structure of microPCMs can be controlled and the properties of microPCMs determined by shell will perform proper practical usage. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4996–5006, 2006     

YAG：Ce Phosphors for WLED via Nano-Pesudoboehmite Sol-Gel Route

The sub-micron sized YAG ： Ce phosphors were synthesized via a modified sol-gel method by peptizing nano-pesudoboehmite particulate. It is found that YAG phase from the dried gel powders appears at 1000 ℃ then the pure YAG phase exists at a relatively lower sintering temperature of 1400 ℃. The smaller sizes of phosphors in the ranges of 1 - 3 μm are obtained due to the contribution of seeding effects of nano-sized alumina particles to strengthen each step of the processes. Both the excitation and emission spectra of photoluminescence of the phosphor obtained at 1400 ℃ meet well with the spectroscopic requirements of the WLED phosphors.     

催化部分氧化法制氢的水碳比控制与探讨

简要介绍了国内少有的干气催化部分氧化转化制氢工艺,重点讨论了转化水碳比的控制条件,对降低水碳比操作进行了有益地探讨。     

纯铜双层辉光离子渗钛组织形成机理及性能分析

采用双层辉光离子渗金属技术对纯铜进行了渗钛处理。用配有能谱仪(EDS)的扫描电子显微镜(SEM)、X射线衍射仪和透射电子显微镜对合金层的显微组织形貌、钛含量分布、相组成及相结构类型进行了观察与测定，对合金层的形成机理进行了探讨，并对其性能进行了对比测定。结果表明：渗钛层由合金层和扩散层组成，合金层主要由TiCu (Cu)固溶体 TiCu4构成，TiCu4为Dla型有序相，TiCu为B2型有序相，扩散层为(Cu)固溶体。渗钛处理后纯铜的表面得到显著强化。     

微波等离子体化学气相沉积的 a-Si∶H 性能研究

本文着重对微波等离子体化学气相沉积法高速沉积的 a-Si∶H 膜的物理性能进行评价研究.测量了沉积膜的光电性能、暗电导激活能、光禁带宽度、光吸收特性、沉积膜中悬键态密度以及氢含量等,并讨论沉积条件对膜性能的影响.结果表明,在沉积速率高达30～90(?)/s 情况下,膜的光电导(光照强度10~5Lux)与暗电导比值可达10~3～10~5,暗电导率从10~(-3)到10~(-11)((?)cm)~(-1),其激活能在0.23～0.88eV 之间(0～200℃温度范围内),光禁带宽度为1.40～2.20eV,氢含量约为2～20%.     

Improved coupled-mode theory for nonlinear directional couplers

An improved coupled-mode equation for nonlinear directional couplers (NLDC) with Kerr-like nonlinear media is proposed. The method is based on the generalized reciprocity relation in which two sets of field solutions satisfying Maxwell's equations are for the NLDC and for the isolated nonlinear waveguide. That leads to a reasonable result that all the coefficients in the coupled-mode equations, including the coupling coefficient, become power dependent. For the NLDC with a self-focusing or self-defocusing nonlinear material, the authors examine how the coupling coefficient, the coupling length, and the guided power depend on the input power in the range of coupling stronger than in previous reports. It is found that the critical power at which the coupling length becomes infinity does not increase as much with the two guides for the case of self-focusing media     

The Hardness of the Closest Vector Problem With Preprocessing Over$ell_infty$Norm

We show that the closest vector problem with preprocessing (CVPP) over lscr _infin norm (CVPP_infin) is NP-hard. The result is obtained by the reduction from the subset sum problem with preprocessing to CVPP_infin. The reduction also shows the NP-hardness of CVP_infin, which is much simpler than all previously known proofs. In addition, we also give a direct reduction from exact 3-sets cover problem to CVPP_infin     

临床检验实验室自动化与实验室国际标准化认可的准备

临床检验实验室的自动化集中管理（LAS）及实验室的认可是目前临检专业讨论比较集中的问题.与传统的实验室比较分散、各自独立的分析设备相比,LAS具有集成度高,能够充分利用检验设备资源,与临床信息系统（CIS）联系更密切的特点.本文就实际临床检验中心投入的实验室集中管理系统,对其结构、流程设计、以及导入自动化系统前后实验室改造所带来的变化进行了分析.     

转炉负能炼钢攻关对策

通过介绍转炉炼钢工艺流程及工序能耗分析，为提高转炉煤气回收量及降低电耗采取了一系列攻关措施，实现了转炉负能炼钢，取得了一定经济效益。     

油脂己烷浸出工程进展

油脂己烷浸出工程经过几十年的发展，在工艺、设备、自控、节能、环保等方面都已趋于完善。装置的规模日趋大型化。车间内的工段组合更加科学、合理与多样化，浅料层浸出器，形式多样化的湿粕脱溶系统，湿粕挤压机，废水零排放系统，不同理念的负压蒸发及余热回收系统，蒸汽冷凝水的再利用，简洁实用的全电脑操作系统，分步萃取，混合油过滤，浸出车间内的混合油碱炼、水化脱胶、磷脂干燥等使得当今的油脂浸出向大型化、集约化、自动化、节能环保的方向发展，为客户提供了越来越多的选择。