Safety-related conclusions for the application of ultrasound in explosive atmospheres

International safety regulations such as EN 1127-1 consider ultrasound to be an ignition source. Currently, applications of ultrasound in explosive atmospheres have to comply with a threshold value of 1 mW/mm². However, it is unclear as to how this intensity has to be measured and, therefore, this threshold value is poorly defined. Moreover, it is based on theoretical estimations in analogy to other ignition sources and there are no publications or significant records on these estimations. Within a research project at PTB, it has now been investigated experimentally in relation to worst-case considerations including airborne ultrasound, focused MHz ultrasound in liquids and acoustic cavitation. On the basis of the results of the research it is now possible to revise the current regulations and to specify measures for safe operation of ultrasonic applications in explosive atmospheres. In this context, for ultrasound coupled directly to gaseous atmospheres a new threshold value of 170 dB (re. 20 μPa) can be suggested, and for ultrasonic applications in liquids, an augmentation can be made to the threshold to 400 mW/mm².     

Monitoring of Butter and Ghee (Clarified Butter Fat) for Pesticidal Contamination from Cotton Belt of Haryana, India

Butter (45) and ghee (55) samples were collected from rural and urban areas of cotton growing belt of Haryana and analysed for detecting the residues of organochlorine, synthetic pyrethroid and organophosphate insecticides. The estimation was carried out by using multi residue analytical technique employing GC-ECD and GC-NPD systems equipped with capillary columns. Butter samples were comparatively more contaminated (97%) than ghee (94%), showing more contamination with organochlorine insecticides from urban samples. About 11% samples of butter showed endosulfan residues above MRL value and 2% samples had residues of synthetic pyrethroids and organophosphates each above their respective MRL values. In ghee, residues of HCH & DDT both and of endosulfan exceeded the MRL values in 5 and 20% samples, respectively. Among organophosphates, only chlorpyriphos was detected with 9% samples showing its residue above MRL value. Irrespective of contamination levels, residues above the MRL values were more in ghee. More extensive study covering other agricultural regions/zones of Haryana has been suggested to know the overall scenario of contamination of milk products.     

南方涝渍地区退田还渔的一个实例分析

以江汉平原四湖涝渍地区的一个经围湖造田形成的典型农业微域为研究对象,在对其土壤和作物生长状况进行调查的基础上,探讨了退田还渔的必要性与具体方案。结果表明,对小型湖泊通过围湖造田所形成的农业微域,在人工排水和土地平整不充分的情况下,其地貌和土壤还残留有原有湖泊的影响,处于原湖泊低处的土壤表现出明显的沼泽化和严重潜育化的特征。在该地区种植水稻产量比正常地区减产达16%～26.8%。利用数量化理论Ⅰ确定了该地区适宜退田还渔的具体位置和面积。按照这一方案实施的结果,该地区从1997～2001年的5年中精养鱼塘面积增加9倍,养鱼的效益比种植水稻高5～10倍,还减轻了该地区夏季和冬季的排水压力。     

菌株HX5对多种染料的吸附作用

研究了HX5生长菌体对分属活性、酸性、碱性、直接和分散5大类的26种染料的吸附性能．结果表明，HX5生长菌体可在5h内完全吸附直接染料和分散染料，碱性染料在生长菌体上完全吸附脱色的时间为12h，其次是活性染料，最不易吸附的为酸性染料．染料在生长菌体上的吸附由染料分子的结构和性质所决定，直接染料分子呈线性平面结构、疏水性较强，易于吸附，完全吸附脱色的时间为5h；分散性染料水溶性较差，在静电力的诱导之下即可在较短时间内完全吸附脱色；碱性染料分子带正电，与带负电荷的菌丝球表面异性电荷相吸从而发生吸附脱色；活性染料分子中的氨基质子化后与菌丝球表面相互吸引，氨基质子化的程度越高，吸附效果也就越好；酸性染料分子中氨基质子化程度受到结构本身的限制，以及不存在带正电荷的基团，因而吸附效果最差．     

极低频电磁场对健康影响的流行病学调查及人体测试研究进展

流行病学调查结果表明，环境的极低频电磁场暴露与人群某些肿瘤，如白血病、乳腺癌、脑肿瘤等，以及生殖、神经、心血管和内分泌等系统疾患的发病相关，这些结果在一定程度上得到实验室人体测试的支持。然而，极低频电磁场对健康影响的确切效应，迄今尚未能作出结论，亟等进一步开展多层次、多水平的研究。     

对中国城市环境地质工作的思考

本文回顾了国内外城市地质工作的发展历程，阐述了中国城市地质工人的发展方向和重点工作领域。指出城市地质工作必须服务于城市（城市群，经济开发区）的规划，建设和管理，为城市社会经济可持续发展，减灾防灾提供具有针对性，实用性和超前性的基础地质资料和成果。由于中国城市的规模，性质，自然资源承载力，地质环境特征不同，城市环境地质调查，评价的对象，内容也将有所差异。归纳起来，城市地质的重点工作领域为：城市可持续发展，城市可持续发展的资源开发战略与对策，城市地质环境容量及脆弱性分析。城市地质灾害：城市地质灾害风险，影响面，易损性及对灾害的反应，城市环境变化的地质指标体系，城市环境地质综合研究：城市环境地质调查评价的新理论，新方法，新技术，城市环境地质图纱的编制。数字城市环境地质：GIS平台上的地质空间数据库，城市地质环境动态分析，评价，决策系统和地质灾害预警预报系统。     

新修农田土壤培肥技术试验研究

黄土丘陵区土地资源主要以坡地形式存在，近年来声势浩大的坡改梯工程使一部分山坡地变为层层梯田，水土保持率明显提高，而如何进行新生土层的土壤培肥，又是该工程的重要课题。作者对当地近几年土壤培肥技术试验进行了研究。以期提高土地资源的利用率。     

油气田采油(气)废水处理设施运行情况调查与评价

通过对全国19个油气田191套采油（气）废水处理设施进行调查，针对其工艺流程、建设投资、处理能力、运行费用、运行状况和处理效果，分析了现有处理方法存在的问题，并提出了解决的办法。对今后处理设施的管理、改进和处理技术的研究有一定参考价值。     

生物技术在油气田环境污染治理中的应用

介绍了生物技术及其在环境污染治理中的应用状况，根据我国油气田环境污染治理现状，提出了生物技术在我国油气田环境污染治理中重点研究的方向和步骤以及应用前景。     

Neurophysiological Effects Induced in the Nervous Tissue by Low-Frequency, Pulsed Magnetic Fields

Summary The influence of pulsed magnetic fields (PMF) on the properties of nervous tissue was investigated. Hippocampal slices or synaptosomes obtained from hippocampal tissue were used as model systems. The amplitude of potentials recorded in vitro from one of the hippocampal pathways (Schaffer collaterals that use glutamate as a neurotransmitter) was employed as a measure of the influence of magnetic fields on synaptic efficiency. The synaptic glutamate turnover and radioactive calcium accumulation were used as markers of the PMF influence on biochemistry of synaptic mechanisms. The exposure of hippocampal slices for 30 min to PMF amplified evoked potentials. While the frequency of 0.16 Hz exerted the strongest effect, lower (0.01, 0.07, 0.03 Hz) and higher (0.5 Hz) frequencies were much less effective. The enhancement of the neuronal excitability was correlated with significant increase in the neuronal spontaneous activity mediated by electrical synapses. The PMF-induced changes in the excitability of the tissue were accompanied by an increase in the synaptic turnover of glutamate. The release of radioactive D-Aspartate (a glutamate analog used as a marker for glutamate turnover) from the slices, and its uptake by synaptosomes were enhanced, and reduced respectively, following the stimulation with pulsed magnetic fields. The frequency which was the most efficient in amplification of evoked potentials (0.16 Hz) was also the most effective in the modulation of the release and uptake processes. The PMF-induced changes in neurotransmitter turnover coincided with an increase in ⁴⁵Ca²⁺ accumulation observed in hippocampal slices exposed to PMF.