管壁特性与摩阻关系

对憎液表面的水力摩阻特性进行了试验研究,实验中憎液表面材料采用聚四氟乙烯,试验工质采用水和7号机械油。试验结果表明,内衬聚四氟乙烯管较普通钢管具有一定的减阻效果,对工质水而言,其减阻效果大约为12％,对7号机械油而言,其减阻效果为6％左右,减阻效果取决于壁面材料对介质的憎液程度,即聚四氟乙烯对水的憎液性能比对7号机械油的好。通过对憎液表面流动机理的理论分析表明,表面经憎液处理后,由于降低了表面能级,使得固壁对液体分子的吸引力小于液体分子间的吸引力,壁面部分流体产生滑移现象,从而达到了一定的减阻效果。     

Acetylcholinesterase-Inhibiting Activity of Pyrrole Derivatives from a Novel Marine Gliding Bacterium, Rapidithrix thailandica

Acetylcholinesterase-inhibiting activity of marinoquinoline A (1), a new pyrroloquinoline from a novel species of a marine gliding bacterium Rapidithrix thailandica, was assessed (IC₅₀ 4.9 μM). Two related pyrrole derivatives, 3-(2′-aminophenyl)-pyrrole (3) and 2,2-dimethyl-pyrrolo-1,2-dihydroquinoline (4), were also isolated from two other strains of R. thailandica. The isolation of 3 from a natural source is reported here for the first time. Compound 4 was proposed to be an isolation artifact derived from 3. The two isolated compounds were virtually inactive in the acetylcholinesterase-inhibitory assay (enzyme inhibition < 30% at 0.1 g L⁻¹).     

滑动弧放电等离子体对枯草芽孢杆菌的灭菌机理

滑动弧放电是在大气环境下产生的一种等离子体形式，放电产生的活性粒子对环境中存在的各种食源性有害微生物具有较好的抑菌效果。以枯草芽孢杆菌为处理对象，研究了放电处理时间对枯草芽孢杆菌的杀菌效果，并通过表面形貌、电导率和共聚焦显微镜等测试方法揭示滑动弧放电等离子体的失活机制。结果表明，氮气放电等离子体具有较好的杀菌效果，主要抑菌机理是对细菌的细胞膜造成破坏，导致细胞坏死。      

Snow forces on forest plants due to creep and glide

Snow forces impede afforestation in the subalpine region; in particular juvenescent trees can be damaged by extraction from the ground. Such forces are mainly triggered by intense snow gliding which is a frequent phenomenon on slopes with a smooth ground surface.