Effect of dietary factors and environmental chemicals on intestinal drug metabolizing enzymes

The liver is the major site of metabolism of foreign chemicals, but contribution from intestinal biotransformation can influence the overall disposition of chemicals. The intestinal drug‐metabolizing enzymes are located in the endoplasmic reticulum and they possess biochemical properties similar to those of the hepatic system. In general, the rate of in vitro metabolism of drug substrates in intestines is lower than in the liver. There seem to be differences in regulation and induction of hepatic and intestinal drug‐metabolizing enzymes. The in vitro intestinal metabolism of foreign chemicals is affected by several factors including the nutritional status of the animal. Dietary components such as vitamins, lipids and vegetables can modify the activities of intestinal drug‐metabolizing enzymes. Phenobarbital or 3‐methyl‐cholanthrene (3‐MC) pre‐treatment induces the hepatic metabolism of a wide variety of drug substrates in a number of species, while the stimulation of intestinal enzymes is both substrate and species specific. Rabbit intestinal drug‐metabolizing enzymes seem to be resistant to induction by foreign chemicals.     

On the association between the column ozone and the spectral solar ultraviolet radiation

An estimation of the increase in the daily spectral solar ultraviolet radiation reaching the ground is attempted, by using the daily total ozone observations made by the Total Ozone Mapping Spectrometer (TOMS) flown on the satellite Nimbus‐7 during 1978–1992. This investigation has been performed for the high latitudes by employing a recently proposed parametric model for the estimation of the spectral solar ultraviolet radiation at the earth's surface considering the total ozone content and various meteorological parameters.     

水稻对UV-B辐射响应的敏感性差异

综述了UV-B辐射对水稻（Oryza sativa L.）的影响和水稻对UV-B辐射的抗性机制。UV-B辐射对水稻生长、叶片形态、生物量、产量、光合系统、病害等产生一定的影响。水稻对UV-B辐射的敏感性因子主要有CPD光解酶、UV-B吸收物质、抗氧化酶等。UV-B辐射使水稻叶片中产生了ROS,导致Rubisco酶降解,光合色素含量变化,抑制了光合作用,最终影响水稻籽粒形成和产量。水稻对UV-B辐射响应存在着品种差异,CPD光解酶编码基因的自然突变会引起水稻UV-B敏感性的差异,CPD光解酶活性是水稻对UV-B敏感性的关键因素。通过建立响应指数公式,对水稻UV-B响应敏感性的品种差异进行评估,存在品种差异的原因主要是基因、生长、生理、生育期和环境背景的差异。最后对UV-B辐射对水稻的影响、水稻对UV-B响应的差异及机理有待深入研究的方向进行了展望。     

微波法处理高浓度氨氮废水

对微波技术处理高浓度氨氮废水进行研究,分别考察了pH值、微波作用时间、曝气与否、初始氨氮浓度对去除率的影响。研究结果表明:pH和微波作用时间是影响氨氮去除率的关键因素,曝气可增强氨氮的去除率效果;浓度为500 mg/L的氨氮废水,在pH为10,微波作用时间为4 min时,曝气去除效果较好,去除率可达81.7%。     

概率火灾安全分析方法研究

为分析和评估火灾对设备、建筑物等敏感目标结构安全的影响,结合化工定量风险评估方法和气体爆炸概率安全分析方法,提出概率火灾安全分析策略和实施流程。该方法包括火灾危害辨识、泄漏速率计算、火灾后果模拟、频率分析、绘制频率超越热载荷曲线、结构响应分析等关键步骤。以某柴油罐区为例,通过频率分析和火灾模拟,绘制出频率超越热载荷曲线,假定火灾风险可接受准则为10-4/a,求得对应的可信热载荷为21 kW/m2,并以此值作为结构热响应分析的输入参数。火灾概率安全分析方法侧重于描述火灾热辐射强度及其对应的发生可能性,判定敏感目标遭遇的可信火灾热载荷强度和结构热响应行为,评估消防减灾措施效果,确保结构完整性和可用性,不评价工艺系统潜在火灾风险的高低。     

Remediation of soil heavily polluted with polychlorinated biphenyls using a low-temperature plasma technique

Polychlorinated biphenyls （PCBs） were removed by low-temperature plasma technique （dielectric barrier discharge） from heavily polluted soil and their intermediate products were analyzed. The removal rate ranged from 40.1 to 84.6% by different treatments, and they were also influenced significantly （P 〈 0.01） by soil particle-size, electric power, gas flow rate and reaction time. The optimal reaction conditions of PCB removal from the soil were obtained experimentally when soil particle-size, electrical power, flow rate and reaction time were 5-10mm, 21w, 120mL. rain and 90rain, respectively. However, decreasing electrical power, flow rate and reaction time to 18 w, 60 mL. min- and 60 min respectively were also acceptable in view of the cost of remediation. This technique was characterized by the additional advantage of thorough oxidation of PCBs in the soil, with no formation of intermediate products after reaction. The technique therefore shows some promise for application in the remediation of soils contaminated with persistent organic pollutants in brown field sites in urban areas.     

不同通风条件下柴油池火的实验研究

为了分析不同通风条件对柴油池火燃烧特性及引燃特性的影响,进行205 mm带水垫层柴油池火的引燃实验,通过对池火燃料的质量损失速率、火焰高度、温度及热辐射等的监测,分析通风环境中柴油池火的热传递规律。结果表明:当风速为0.5 m/s时,火灾进入旺盛阶段的时间提前,火焰平均温度最高;当风速为1 m/s时,风速的增加导致油池火的质量损失速率增加,位于主火源下风向的待引燃火源获得的热辐射通量增大,火灾旺盛阶段火焰的平均温度降低,火焰高度降低,下风向相邻油盘引燃的时间提前;1 m/s情况下,205 mm带水垫层柴油池火的安全间距需增加到1D以上;通风环境对池火发展及蔓延的影响是显著的,应适当加大下风向可燃物的安全间距,合理选择通风排烟风速,优化火灾应急救援策略。     

铀矿开采对环境的影响及治理的特殊性

从铀矿开采对环境影响的特殊性着手．详细分析了铀矿山开采对环境造成的放射性这一特殊影响,同时也对目前广泛应用的一些处理方法做了简明的介绍。     

A Graphical Method for the Estimation of Radiation Hazards from a Crowded Multiple Antenna Site

Summary The major objective of the design of safe crowded transmitting antenna sites is not only to determine a safe zone around each individual antenna; rather, to establish safety areas at the antenna site itself, as well as, at the neighboring areas. The requirement is to ascertain the safety regions by considering the following parameters at each Test Point (TP) (or area segment): the contribution of N co-located radiating antennas to the total radiation incident at the TP, the radiation pattern of each antenna, the near/far field region of each antenna, and most importantly, the different Permissible Exposure Limits (PELs) associated with each operating frequency at the antenna site. Implementation of all the above-mentioned aspects in a suitable computer requires resources that only expert knowledgeable organizations possess. The graphically aided tool presented in this paper facilitates the calculation of a “safety zone” for RADHAZ around a crowded antenna site from the knowledge of the “safety ranges” which correspond to the individual transmitting antennas comprising it.     

南黄海Ms6.1地震电磁辐射特征

介绍了长江三角洲观测台网记录到的南黄海６．１级地震电磁辐射异常，并结合１９７９年溧阳Ｍｓ６．０、１９８４年南黄海Ｍｓ６．２地震前的电磁辐射观测资料及国内其它资料，分析了异常的主要特征。初步讨论了ＤＰＪ型电磁辐射观测仪的甚低频段及ＵＬＦ型地震电磁信息观测仪的超低频段天线方向特性对震中预测的意义问题