Uranium enrichment by the separation-nozzle process

The Science of Nature - The development of reliable manufacturing methods for commercial separation elements, the successful operation of separative stages, and extensive tests performed on plant...     

Simulating a thermal water quality trading market for education and model development

Thermal water quality trading is an emerging policy tool that allows thermal polluters to comply with effluent restrictions by paying landowners to plant shade trees. A simulation game was created to help participants understand the structure, dynamics, benefits, and drawbacks of thermal water quality trading markets. Simulation participants negotiate to make trades, and their decisions are entered into a system dynamics model that simulates tree growth and water temperature. A debriefing session allows the participants to discuss outcomes and strategies. The exercise has been performed twice and has proven to be a useful teaching tool. These simulations provided valuable insight into decision-making strategies in thermal water quality trading markets, suggesting decision rules that the researchers used for subsequent model development.     

Some toxicological aspects op methamidophos exposure in mice 1

Abstract

Cholinesterase activity in the brain, RBC and plasma of Swiss mice was determined following different routes of administration of methamidophos. Continuous feeding with the insecticide caused a progressive inhibition of both plasma‐ and erythrocyte enzymes. The effect of methamidophos was more pronounced when applied in diet than when administered dermally or intraperitoneally. Following a single injection (i.p.) of methamidophos, the brain enzyme showed maximum inhibition 24 hr following treatment. At the appearance of tremors, the plasma and RBC‐enzymes showed considerable inhibition, the former being more inhibited. The plasma enzyme appears to be the most sensitive enzyme and may be taken as a suitable index for exposure to methamidophos.     

VILLAGE DEMONSTRATION OF BIOGAS TECHNOLOGY: AN EGYPTIAN CASE STUDY

Within the context of biogas R & D and demonstration project undertaken by the Egyptian National Resarch Centre, village demonstrations are of paramount importance. In this paper, a case study of a pioneering village demonstration is presented. Based on a preliminary sociological survey, “Al Manawat” - a traditional Egyptian village was selected for the first demonstration. After a short orientation phase through which the biogas technology was introduced to a group of village representatives, a family was selected to conduct the demonstration experiment. Concomitant with the family energy requirements, availability of digester feed materials, site characteristics and other relevant factors, a family-size unit of a modified Indian type was designed and erected by the side of the farmer's house. The digester effective volume is 9 cu.m. and is connected to both a latrine and animal shed. The unit has been successfully operated since May 1981. The highlights of the construction stage as well as the unit performance characteristics are discussed. A preliminary techno-economic appraisal is also outlined. Finally, social impacts are assessed. Initial results indicate that under the Egyptian village conditions, and particularly with the heavily subsidized fuel prices, the high saving in manure transport attained through the introduction of the biogas unit, appears to be the main benefit from the farmer's point of view. Dans le cadre de la recherche et du développement du gaz de fermentation et d'un projet pilote entrepris par le Centre national de recherche égyptien, les démonstrations faites dans les villages occupent une place prépondérante. Dans cet article, l'auteur présente le cas-type d'une démonstration pilote faite dans un village. En se basant sur une enquêue sociologique préliminaire, “Al Manawat”, qui est un village égyptien traditionnel, a été choisi comme lieu de la première démonstration. Après une courte phase d'orientation au cours de laquelle le technologie du gaz de fermentation a été présentée à un groupe de notables du village, on a choisi une famille pour effectuer la démonstration expérimentale. En même temps que l'on étudiait les besoins énergétiques de cette famille, la disponibilité de matières de base de fermentation, les caractéristiques de l'emplacement et tous autres facteurs pertinents, une unité familiale de type indien modifié a été con?ue et érigée à côté de la ferme. Le composteur, d'un volume utile de matières premières de 9 m³, est relié à la fois aux latrines et à l‘étable. Cette unité fonctionne avec satisfaction depuis le mois de mai 1981. L'article met en avant les points essentiels des étapes de la construction et les caractéristiques de rendement de l'unité de fermentation. Il esquisse une évaluation technico-économique préliminaire et fait l'estimation des retombées sociales. Les premiers résultats montrent que, dans le cadre du village égyptien et particulièrement du fait que les prix du fuel sont largement subventionnés, les économies importantes réalisées dans le transport du fumier grâce á l'introduction de l'unité de fermentation semblent étre, du point de vue du fermier, le bénéfice principal. Dentro del contexto del proyecto de I & D y demostración realizado por el Centro de Investigación Nacional de Egipto, la demostración en los villorrios es de suma importancia. Este artículo presenta un caso pionero de este tipo. Basado en encuestas sociológicas, un villorrio tradicional de Egipto, “Al Manawat” fue selectiondo para la primera demostración. Después de una fase corta de orientación en la que se introdujo la tecnologia del biogás a los representantes del villorrio, se seleccionó una familia con cuya colaboración se Ilevaria a cabo el experimento. Teniendo en cuenta las necesidades de energia de la familia, la disponibilidad de materia prima para el digestor, las caracter ísticas del lugar y otros factores importantes, se diseñó y construyó un digestor de tamaño familiar, usando un modelo Indio, al lado de la casa de la familia. El volumen efectivo del digestor es 9 metros cúbicos y está conectado a la letrina y al corral de animales. La unidad está funcionando con éxito desde Mayo de 1981. Se discuten aspectos de la etapa de construcción y las características de operación. Se hace también una evaluación técnico-económica preliminar. Finalmente se evalúa el impacto social de la experiencia. Los resultados indican que en las condiciones de los villorrios Egipcios, especialmente en condiciones de precios de combustibles altamente sub-sidiados, los grandes ahorros en el transporte de abono debido a la introducción del digestor de biogas parece ser el mayor beneficio desde el punto de vista de la familia.     

Effects of mercury graded doses on redox status,metallothionein levels and genotoxicity in the intestine of sea cucumber Holothuria forskali

Mercury (Hg) is a ubiquitous and a major environmental metal pollutant in the aquatic ecosystem. The present study was performed to evaluate the effect of mercury graded doses exposure on oxidative stress, redox status, metallothionein levels and genotoxicity in the intestine of sea cucumber Holothuria forskali. Specimens were exposed for 96?h to three concentrations of Hg (40, 80 and 160?µg/L). Exposure of H. forskali to Hg promoted oxidative stress with an increase in malondialdehyde (MDA), protein carbonyl (PCO) and advanced oxidation protein products (AOPP) levels. An increase of glutathione (GSH), vitamin C (ViteC) and non-protein thiols (NPSH) contents was also observed. Additionally, antioxidant activities of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) increased especially with the highest doses of Hg indicating a great defense of the antioxidant system. Our investigation revealed an increase in total Metallothionein (MT) content which was more pronounced at the sharpest concentrations of Hg. A significant decline of AChE activity was also observed. In the intestine of Hg-treated H. forskali genotoxicity was confirmed by DNA degradation.     

Effect of slow release nitrogenous fertilizers and biochar on growth,physiology, yield,and nitrogen use efficiency of sunflower under arid climate

Environmental Science and Pollution Research - Sunflower plants need nitrogen consistently and in higher amount for optimum growth and development. However, nitrogen use efficiency (NUE) of...