健康城市住区的热环境探析

在经历"非典"疾病流行事件后,人们痛定思痛,从不同角度对人居环境进行了反思,健康的概念前所未有地成为社会各界关注的重点.热环境是人居环境的重要组成方面,保持良好的热环境是健康城市、健康住区和人体健康的重要前提.分析城市热环境的特征及其影响效应,探讨在整体、系统和生态气候学的原则下改善城市住区热环境的途径,对于营造健康的人居环境起着重要作用.     

Metabolic and histological analysis of mesenchymal stem cells grown in 3-D hyaluronan-based scaffolds

Sheep mesenchymal stem cells (MSCs) were isolated and expanded using the principle of plastic adherence. Their identity as progenitor cells was confirmed by induction along the osteoblastic lineage using osteogenic supplements and observation of calcific deposits by von Kossa staining. MSCs were seeded onto two types of hyaluronan-based cylindrical scaffolds in high concentrations and cultured for varying time points up to three weeks. Culture medium was supplied using the following conditions: statically, on a shaker, by stirring with a magnetic stirrer or by perfusion in a tubular flow circuit. Total cell metabolism was assessed by MTT assay and the quality of cell coverage and matrix formation observed by SEM and histological analysis of thin sections of the constructs. Perfusion culture was established as the most appropriate culturing conditions, with cell metabolism increasing by approximately 300% over three weeks. The coverage of the scaffold surface was very good and the deposition of collagenous matrix was superior in these conditions compared to the, static and other dynamic culture conditions.     

Thermodynamic analysis of water interaction with excipient films

The interaction of water with excipients that can form moisture-protective coatings was examined earlier by the application of theoretical models. In this study, thermodynamic analysis of water-excipient film systems has been performed to elucidate the mechanistic details of the water-excipient interaction. Partial molal free energies, enthalpies, and entropies were computed for films of lipidic (glyceryl behenate, GB) and polymeric (polyvinyl alcohol, PVA) coating excipients using the temperature dependence of the adsorption process. The analysis of free energy changes showed that excipient films were not inert participants in the water sorption process. The isoteric heats of adsorption confirmed that water formed hydrogen bonds with the excipient films and allowed estimation of number of hydrogen bonds per water molecule. This result also provided the reason for hysteresis during drying. A comparative evaluation of the application of theoretical models and thermodynamic analysis revealed that results obtained from both approaches were not always complementary. An exponential relationship was found to exist between sorption microrate constants and water activity for the PVA films at all temperatures.     

Heat transfer rate predictions in condensation on droplets from air-steam mixtures

This paper describes simulations of the combined heat and mass transfer to single water droplets falling freely in air-steam mixtures. The effects of droplet size, initial velocity, and concentration of steam in the mixture are discussed. The results are to be used in the design synthesis of steam dousing chambers in which sprays containing droplets whose diameters range as high as 6 mm. are used.     

Potential use of Liquid Membranes for Emergency Treatment of Drug Overdose

Several liquid membrane formulations were evaluated for the absorption of model drugs from two different donor solutions. Up to 95% of both phenobarbital and aspirin (acetylsalicylic acid) were removed from pH 2 donors and more than 85% of the former from a pH 7 donor in     

电网故障信息管理系统的开发

为充分利用微机保护和录波器存储的信息，进一步提高电网运行管理水平，提出电网故障信息管理系统采用成熟的通信技术将信息直接从变电站传送到调度部门，使故障信息得以共享，由于采用GPS技术，确保了系统中的时钟具有相同的时标，提高了被传送的故障信息的同时性，有助于故障分析和故障定位。文章介绍了系统的设计和应用情况。     

基于超短基线的缆控水下机器人动力定位

动力定位 (DynamicPositioning(DP) )技术是水下机器人的关键技术之一。因此针对当前动力定位主要在缆控水下机器人 (ROV)中应用的情况 ,给出了ROV动力定位技术的实施方法。通过声学定位技术确定ROV的坐标 ,计算出与期望位姿的差 ,将其作为神经网络控制器的输入量来控制ROV ,从而进行动力定位。同时还重点研究了ROV动力定位中的主要研究内容即水声定位技术和定位控制技术的构建。