Classification of powders in the electric field

Translated from Poroshkovaya Metallurgiya, No. 12, pp. 10–14, December, 1990.     

Influence of the electric field strength and hydrogen on the rate of removal of iron atom impurities in refining remelting of tantalum

A comparison of the results of electron beam remelting (EBR) of tantalum and plasma arc remelting (PAR) of tantalum in a hydrogen atmosphere shows that some impurity elements are removed better during PAR with hydrogen than during EBR. The refining mechanism, the role of hydrogen, and the change in the electric field strength during the removal of impurity elements from tantalum are analyzed by molecular dynamic simulation.     

带电圆盘导体电场的电势和场强

导出了带电薄圆盘导体空间电场的电势和场强表达式，并作出了相应的分布曲线．     

Preparative concentration and size fractionation of DNA by porous media using a combination of flow and low electric field strength

Reinstatement of drug-seeking behavior after extinction constitutes a potential animal model of relapse to drug abuse. In a typical reinstatement experiment, previously drug-trained rats undergo extinction during which responding is no longer followed by drug delivery. After significant extinction is observed, rats are then exposed to an event expected to reinstate drug-seeking behavior. Using this procedure, it has been recently reported that footshock stress leads to reinstatement of drug-seeking in heroin-trained, presently drug-free rats. The purpose of the present study was to assess the generality of this effect of stress. Here we report that 15 min of intermittent footshock (0.86 mA; 0.5 s on, with a mean off period of 40 s) reinstated selectively cocaine-seeking behavior after 14 extinction sessions (rats were previously trained on a FR1 TO 20 s to obtain cocaine at a dose of 0.25 mg/infusion). In contrast, under similar experimental conditions, the same stressor did not reinstate food-seeking in food-trained rats after seven extinction sessions (rats were previously trained on a FR1 TO 20 s to obtain six food pellets). Rather, when the basal level of responding was sufficiently high, footshock stress induced a significant suppression of the instrumental performance. These data are discussed in light of several behavioral mechanisms which may explain the specificity of stress in reinstating drug-seeking behavior and not food-seeking behavior.