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基于闪电低频电场探测阵列（LFEDA）所获得的全闪三维定位数据,研究了2015年8月15日14:30—16:10广州一次雷暴过程中具有明显始发脉冲的闪电初始放电特征及放电规律。结果表明:212例近距离云闪和地闪中,32例闪电由窄偶极性放电事件（NBE）始发,占15%;180例闪电由初始击穿脉冲（定义初始击穿脉冲簇的首个脉冲为FIBP）始发,占85%。作为始发的窄偶极性放电事件（INBE）,其相对孤立且具有较大的相对幅度,INBE与后续闪电的第1个脉冲的时间间隔为7 ms,幅度比为3.5,远大于FIBP相对应的时间间隔0.6 ms和幅度比0.8,INBE后多跟随传统的IBP脉冲。多数正极性INBE与FIBP对应初始向上发展的闪电,而负极性对应初始向下发展的闪电。INBE始发闪电前15 ms的平均发展速度随始发高度的增大而减小,快于FIBP,这与INBE具有更快的速度相关。估计的INBE速度为4.7×107 m·s-1,FIBP速度为1.5×107 m·s-1,两者速度差异也体现在脉冲上升时间方面,INBE具有更快的上升沿。 相似文献
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Cholinesterases (ChEs) have been characterized in marbled sole (Limanda yokohamae) for use as a possible biomarker of pollution exposure. In brain, ChEs existed almost exclusively (>95%) as acetylcholinesterase (AChE) whereas in muscle, about 20-30% of ChE activity was in the form of butyrylcholinesterase (BChE; pseudocholinesterase). Acetylthiocholine and butyrylthiocholine (identified in mammalian studies as diagnostic substrates for AChE and BChE respectively) were hydrolyzed mainly, but not exclusively, by these enzymes. The inhibitors BW284C51 and iso-OMPA (identified in mammalian studies as diagnostic inhibitors of AChE and BChE respectively) were not specific for these enzymes in marbled sole. Brain AChE and muscle AChE and BChE were characterized in terms of their kinetic properties (KM etc.) and optimal conditions (substrate concentration, protein concentration, pH etc.) were established to allow routine assays of ChE activity to proceed under pseudo-first order conditions. The sensitivity of ChEs to a locally significant pesticide, iprobenfos (IBP; kitazin) was established in terms of IC50 concentrations. Brain AChE was relatively insensitive to IBP, but muscle AChE and BChE were sensitive to IBP concentrations in the high nM range. However, ambient IBP concentrations in Korean coastal waters are usually not high enough to cause detectable ChE inhibition in this species. 相似文献
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