Effects of Temperature, Substrate Concentration and pH on the Polycyclic Aromatic Hydrocarbon Pyrene Biodegradation by Arthrobacter sp. NJ5 Strain

Polycyclic aromatic hydrocarbons (PAHs) are widely distributed in the environment and may persist for extended periods of time. PAHs are one of the most important classes of persistent organic contaminants. High molecular weight (HMW) PAHs (compounds containing four or more fused benzene rings) are generally recalcitrant to microbial attack. Until recently, only a few genera of bacteria have been isolated with the ability to utilize four-ring PAHs as sole carbon and energy sources. Because of the toxic, mutagenic, and carcinogenic characteristics of some, PAHs have been studied extensively by many scientists around the word. This paper presents research results, where 10 microbial strains belonging to genus Arthrobacter sp. and obtained from culture collection of JSC "Biocentras"were tested for the best biodegradation of HMW PAH pyrene. Pyrene degradation experiments were conducted in liquid mineral medium. Pyrene concentration was 0. 2 mg/mL at the beginning of degradation experiments. After 72 h incubation with ten Arthrobacter sp. strains, gas chromatography analysis revealed that highest pyrene degradation (19%) was reached by Arthrobacter sp. NJ5 strain. The effect of medium pH, pyrene concentration and temperature on the intensity of the degradation by the most active strain Arthrobacter NJ5 was investigated

MICROWAVE EXPERIMENTS INCLUDING AVALANCHE

Dans cet exposé sommaire, on décrit les principes des techniques le plus souvent utilisées des micro-ondes destinées à l'étude des électrons chauds dans les semiconducteurss on présente aussi l'état actuel des recherches dans le domaine des électrons chauds effectuées dans le champ électrique des micro-ondes. On souligne surtout les expériences ou l'on utilise la spécifité d'échauffement par le champ des micro-ondes aussi bien que celles qui ont permis de compléter l'information concernant le champ électrique continu.The principles of the most popular microwave techniques for hot electron investigations in semiconductors are briefly described and the current status of hot electron investigations with microwaves is reviewed. The emphasis is put on the experiments which make use of the specific features of microwave heating or give an extra information in addition to that obtained from d.c. measurements

Effect of interparticle collisions on energy relaxation of carriers in semiconductors

An Ensemble Monte carlo simulation is used to calculate the dynamics of charge carriers in semiconductors in the presence of interparticle collisions