‘Waldsterben’, part IV (continuing series)

Summary Peroxidase and superoxide dismutase activities, and ascorbic acid content, were measured in both intercellular fluid and cell material of current and 1-year-old needles of Norway spruce saplings treated with ozone, ambient air and activated carbon-filtered air in outdoor fumigation chambers. Ethylene evolution was also compared. Plants from carbon-filtered air treatments had significantly lower enzyme activities and higher ascorbic acid content. These changes were more marked in intercellular fluid than in cell material. Significant changes were noted at ozone levels typical of ambient air quality in a typical urban area. These results suggest the need for simultaneous screening of several biochemical markers as a way of overcoming the lack of specificity of any single marker for the identification of a perturbation by a particular stress, such as ozone.Acknowledgments. This work was supported in part by Grant Number 4849-0.85 (NFP 14) from the Swiss National Fund of Scientific Research. We thank Dr. F. Cupelin and Dr. J. Cl. Landry from the Service d'Ecotoxicologie, Genève, who provided the facilities for the monitoring of ozone levels. We also thank A. Mesrobian, A. Rossier and D. Voluntaru for technical assistance. Du Pont de Nemours International is gratefully acknowledged for the gift of TEDLAR (polyvinyl fluoride film) to build up the fumigation chambers.     

Enhanced calcification ameliorates the negative effects of UV radiation on photosynthesis in the calcifying phytoplankter <Emphasis Type="Italic">Emiliania huxleyi</Emphasis>

The calcifying phytoplankton species,coccolithophores,have their calcified coccoliths around the cells,however,their physio-logical roles are still unknown.Here,we hypothesized that the coccoliths may play a certain role in reducing solar UV radiation(UVR,280-400 nm) and protect the cells from being harmed.Cells of Emiliania huxleyi with different thicknesses of the cocco-liths were obtained by culturing them at different levels of dissolved inorganic carbon and their photophysiological responses to UVR wer...     

光化学原位制备PDEA-磁性纳米凝胶用于DNA 固定及缓释研究

应用光化学原位聚合法合成了聚(甲基丙烯酸二乙氨基乙酯)包覆的磁性纳米凝胶 (PDEA-磁性纳米凝胶). 应用傅里叶变换红外光谱(FTIR)、热重分析仪(TGA)、振动样品磁强计 (VSM)、光子相关光谱(PCS)等对PDEA-磁性纳米凝胶的结构、形貌、磁学性质、粒径及表面 ζ-电位等进行了表征. 结果表明, PDEA-磁性纳米凝胶形状较规则, 为“核-壳”结构, 表面PDEA高分子层约为26%, 平均水合粒径为43 nm, 具有超顺磁性. 该磁性纳米凝胶具有明显的pH敏感性, 在室温、 pH 5.0时可结合DNA分子, 最大结合量为51 μg/mg, 在pH 7.4条件下能够将DNA高效释放出来, 且呈现出明显的缓释效应, 加之良好的磁响应性能, 使其可作为一种新型磁靶向转基因载体应用于生物医学研究.     

Long-day photoperiod induced unhealthy development of chloroplasts in the photoperiod-sensitive genie male-sterile rice

By measurement of photochemical activities of chloroplasts and observation on supramolecular archi tecture of thylakoids in chloroplasts, it was found that compared with the effects of short-day photoperiod, long-day pho toperiod could induce normal development of chloroplasts in seedlings of NK58S (photoperiod-sensitive genie male-sterile rice) and NK58 (original line) which do not enter the photoperiod sensitive phase and in seedlings of NK58 just enter the photoperiod-sensitive phase. However, it could induce unhealthy development of chloroplasts in seedlings of NK58S which also just enter the photoperiod sensitive phase. This special effect of long-day photoperiod on the development of chloroplasts in NK58S is probably one of main reasons why long-day photoperiod induces rale-sterility in NK58S and normal fertility in NK58.     

吡啶光氯化反应机理的量子化学研究(II)——PM3计算吡啶光氯化反应体系能量与反应动力学分析

用量子化学方法 PM3结构参数全优化方法对吡啶光氯化反应所涉及的分子、自由基进行了能量计算 ,得到键解离能 ,并对反应活化能与动力学进行分析 .对吡啶光氯化反应 ,提出了氯自由基直接进攻吡啶环的碳原子和氯自由基首先夺取与吡啶环键链的氢原子两种不同的反应机理 .量化计算结果表明 :吡啶光氯化反应中夺氢反应机理所需的反应活化能较低 ,不同产物以生成2 -氯吡啶的活化能最低 ,为 1 74.0 8k J/mol,总反应级数为 1 .5级 ,对吡啶的分级数为 1级 .对氯气的分级数为 0 .5级 .     

城市大气中甲醛来源分析的示踪技术

甲醛是城市大气中浓度水平最高的含氧挥发性有机物。甲醛在城市地区主要来自机动车尾气排放等一次来源及大气光化学反应二次来源。然而,目前识别甲醛一次和二次来源的研究开展得较少。基于大气一次污染和二次污染示踪物的统计分析方法,是大气甲醛来源分析的新进展。作者介绍了采用示踪物估算城市大气甲醛来源贡献的技术方法和初步结果,并针对示踪物的特点讨论了该方法的适用性。     

火力发电的环保性现状研究

火力发电是我国重要的发电形式,承担着我国一半以上的电力供应任务。同时,火力发电也对环境有着一定的污染,了解我国火力发电的环保性现状,并有针对性的采取相应的改进措施,对我国环境保护战略的实施和电力行业的发展有着重要的意义。文章分析了火力发电对环境产生的不良影响以及我国火力发电行业的环境保护现状和存在的问题,并提出了提高火力发电环境保护工作的有效措施。     

单壁碳纳米管的光化学活性研究

本文采用间歇式超声法制得能够在水体中稳定分散的单壁碳纳米管,考察了单壁碳纳米管在模拟太阳光照下产生活性氧的能力.分别以呋喃醇和对氯苯甲酸为探针,发现在模拟太阳光下单壁碳纳米管能够产生单线态氧和羟基自由基,其产生单线态氧的能力与自身浓度成正比,是相同浓度SRFA的1/9~1/5,单壁碳纳米管产生羟基自由基的能力与自身浓度成反比,是相同浓度SRFA的2/5~1/2.     

光化学衍生检测玉米中4种黄曲霉毒素

建立了HPLC-免疫亲和柱净化,柱后光化学衍生检测玉米中4种黄曲霉毒素B1,B2,G1,G2的分析方法。玉米样品提取、浓缩、过滤后经免疫亲和柱净化,液相色谱分离后采用光化学衍生器对黄曲霉毒素B1,B2,G1,G2进行在线衍生,通过配制荧光检测器的液相色谱同时检测玉米中B1,B2,G1,G2这4种黄曲霉毒素。结果表明,4种黄曲霉毒素B1,B2,G1,G2的色谱分析时间在6～11min内完成,检测定量限分别为:0.10,0.03,0.10,0.03μg/kg,完全符合并高于欧盟检测标准定量限,通过光化学衍生器在线衍生将B1、G1的分析定量限提高到2.7倍和3.6倍。玉米基质中B1,B2,G1,G2在添加水平为10,3,10,3μg/L时其回收率分别为:90.3%,85.6%,93.5%,92.8%。其线性范围分别为0～20μg/L,0～6μg/L,0～20μg/L,0～6μg/L,RSD 分别为 2.3%,1.5%,2.7%,3.2%。文章建立了分析玉米中4种黄曲霉毒素B1,B2,G1,G2的分析方法,经验证该方法定性准确,定量灵敏度高,可同时检测出玉米中4种黄曲霉毒素B1,B2,G1,G2含量。     

光化学烟雾及防治对策的探讨

文章分析了光化学烟雾形成的原因，讨论了其形式的机理以及造成的危害，同时提出了防治光化学烟雾的一些对策．