配电自动化系统载波组网通信方式研究

在介绍中压配电线路载波通信技术应用状况的基础上,分析了PLC-075型电力线数据传输装置在配电网自动化系统载波组网通信中的具体应用,并提出深圳配电网利用电力电缆屏蔽层载波通信传输配电自动化数据的典型设计方案、存在的技术难题、将来的研究目标。     

高动态卫星链路多普勒频移特性分析

为满足高动态卫星接收机设计仿真及测试需求,以高机动飞行器典型运动模型为参考,通过合理近似与简化,推导出高动态卫星信道多普勒频偏变化理论模型。仿真结果表明,理论模型的多普勒频偏计算误差小于6‰,适合工程设计应用。在此基础上,进一步分析了高动态卫星通信信号载波同步关键技术,并提出了解决方案建议。     

简单、快速测定酵母活力的新方法

介绍南非酿酒公司常规检测酵母质量的方法,测试过程为测定酵母泥湿重或生物量--测定酵母悬浮液的pH值--测定酵母悬浮液的蛋白酶活力--测试酵母细胞镁离子释放.     

Polymeric sodium alginate interpenetrating network beads for the controlled release of chlorpyrifos

Novel polymeric sodium alginate (Na‐Alg) interpenetrating network (IPN) beads have been prepared by crosslinking Na‐Alg blend with gelatin (GE) or egg albumin (EA) using glutaraldehyde (GA) as the crosslinking agent. These beads were used for the controlled release of chlorpyrifos. The swelling experiments were performed in water at different temperatures, and these data were used to calculate the molecular mass (M_C) between crosslinks as well as diffusion coefficients. Diffusion coefficients calculated from desorption data were lower by about two orders of magnitude than those calculated from sorption results. Higher values of M_C were obtained for the gelatin‐based IPNs than the neat Na‐Alg and egg albumin‐based matrices. Size of the beads did not vary significantly either by the network or by increasing the exposure time to the crosslinking agent. The scanning electron microscopy (SEM) was used to understand the surface characteristics of the beads. Differential scanning calorimetry (DSC) indicated a molecular level dispersion of chlorpyrifos in the polymer matrix. The percentage entrapment efficiency showed a dependence on the type of network polymer as well as time of exposure to the crosslinking agent. The encapsulation efficiency decreased with an increase in time of exposure to the crosslinking agent. In vitro release experiments have been performed to follow the release kinetics of chlorpyrifos from the matrices. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 911–918, 2002     

Delayed release matrix pellet preparation containing an alkalizing pore-former agent

The aim of this study was to develop a delayed-release matrix pellet containing atenolol as active pharmaceutical ingredient. The matrix additionally contained trisodium phosphate dodecahydrate as alkalizing pore-former agent to enhance the dissolution of the atenolol at pH 6.8. The delayed release was ensured by coating with a gastro-resistant polymer. For this purpose, an acryl EZE MP aqueous dispersion was used, which is suggested in the literature for pellet coating. Before this functional film coating, a protective polymer layer was developed, to prevent direct contact between the alkalizing layer and the acryl EZE. The results of in vitro dissolution tests demonstrated that the double-coated pellet preparation is a delayed-release solid dosage form.     

pH Dependent Controlled Release of CTAB Incorporated Dipyridamole Drug from Agar-Based Hydrogel

Highly pH sensitive hydrogels, based on agarose and acrylamide were synthesized and characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimeter, and scanning electron microscopy. The release of dipyridamole from the hydrogel matrix was monitored using fluorescence spectroscopy. Since the solubility of the drug gets enhanced by cationic surfactant, an inclusion complex was prepared using cetyl trimethylammonium bromide and the release of inclusion complex from the polymer matrix was also studied. Swelling behavior of the prepared hydrogels in different pH media were studied at room temperature and maximum swelling was observed at basic pH.     

车载超短波电台维修检测系统的设计与实现

针对某新型车载超短波电台原理结构复杂、自检虚警率高、故障定位困难等问题,综合采用嵌入式技术、数据库软件、电路智能检测等技术,以车载超短波电台维修检测主机+模件测试夹具的架构构建硬件平台,研制开发车载超短波电台维修检测系统;该系统能够实现对车载超短波电台整机频率误差、输出功率、接收灵敏度等参数及电台内部模件性能指标的自动化测试,测试结果与标准特征值比对,实现电台整机技术状态评估和模件级故障定位,实现电台维修信息的实时存储与查询,从而解决陆军部队车载超短波电台维修检测手段不足、维修保障困难等实际问题。     

耐硫变换催化剂载体抗水合性能的研究

模拟我国化肥工业耐硫变换新工艺条件,考察了以γ－Ａｌ２Ｏ３、ＭｇＡｌ２Ｏ４尖晶石为载体的耐硫变换催化剂的抗水合性,研究载体水合后对催化剂性能的影响,得出一些对化肥新工艺催化剂选型具有参考价值的结论。     

Development of extended release dosage forms using non-uniform drug distribution techniques

Development of an extended release oral dosage form for nifedipine using the non-uniform drug distribution matrix method was conducted. The process conducted in a fluid bed processing unit was optimized by controlling the concentration gradient of nifedipine in the coating solution and the spray rate applied to the non-pareil beads. The concentration of nifedipine in the coating was controlled by instantaneous dilutions of coating solution with polymer dispersion transported from another reservoir into the coating solution at a controlled rate. The USP dissolution method equipped with paddles at 100 rpm in 0.1 N hydrochloric acid solution maintained at 37°C was used for the evaluation of release rate characteristics. Results indicated that (1) an increase in the ethyl cellulose content in the coated beads decreased the nifedipine release rate, (2) incorporation of water-soluble sucrose into the formulation increased the release rate of nifedipine, and (3) adjustment of the spray coating solution and the transport rate of polymer dispersion could achieve a dosage form with a zero-order release rate. Since zero-order release rate and constant plasma concentration were achieved in this study using the non-uniform drug distribution technique, further studies to determine in vivo/in vitro correlation with various non-uniform drug distribution dosage forms will be conducted.