https://dspace.univ-ouargla.dz/jspui/handle/123456789/3981 Wed, 15 Apr 2026 16:37:24 GMT 2026-04-15T16:37:24Z https://dspace.univ-ouargla.dz/jspui/handle/123456789/6422 Titre: EFFET DE L'AGENT ENTRAINEUR D'AIR SUR LA RESISTANCE DES BETONS EXPOSES AUX CYCLES GEL DEGEL Auteur(s): M. MECHKOURI; A. GUETTALA Résumé: The concretes made in cold and wet climates zones, as the case works located in the highlands in Algeria, may suffer damage caused quite remarkable development constraint large enough within the structure of concrete due to the effects of cycles of freeze defreeze. The main objective of our study is to develop a set of dosages of air entraining admixture within the concrete mixtures when mixing with the purpose of developing a formulation to ensure concrete durability better with time and protect including repeated cycles of freeze defreeze. These formulations are to have a better rheological behaviour vis-à-vis the workability without a significant loss of strength that exceeds the standards. The results of this study highlight that the inclusion of air-entraining agent in concrete to a beneficial effect, particularly on the resistance to freeze defreeze cycles. A significant improvement on the rheological and mechanical behavior of concrete against the effects of freeze defreeze was observed. Description: AST Annales des Sciences et Technologie Thu, 01 Jan 2009 00:00:00 GMT https://dspace.univ-ouargla.dz/jspui/handle/123456789/6422 2009-01-01T00:00:00Z https://dspace.univ-ouargla.dz/jspui/handle/123456789/6420 Titre: EXTENSION OF REKKER METHOD FOR THE PREDICTION OF NOCTANOL / WATER COEFFICIENT OF FERROCENE DERIVATIVES Auteur(s): Ridha AHMEDI; Touhami LANEZ Résumé: Octanol/water partition coefficients logP of many selected substituted ferrocenes were predicted by calculation for the first time using the fragmental Rekker method. The calculated values of logP were compared with the experimental values. For estimation of the logP of the selected substituted ferrocenes, the average absolute error of logP is 0.08. Although the obtained values of logP by the proposed method are all very close to the experimental values, the values of logP obtained for ferrocene derivatives that do not contain a bulky group in their structure were significantly better than the results obtained for those containing a bulky group. Description: AST Annales des Sciences et Technologie Thu, 01 Jan 2009 00:00:00 GMT https://dspace.univ-ouargla.dz/jspui/handle/123456789/6420 2009-01-01T00:00:00Z https://dspace.univ-ouargla.dz/jspui/handle/123456789/6419 Titre: CHARACTERIZATION OF THIN TITANIUM FILMS DEPOSITED ON STEEL SUBSTRATES OBTAINED BY MAGNETRON SPUTTERING METHOD Auteur(s): Rachid GHERIANI; Rachid HALIMI Résumé: Titanium carbides are well known materials with great scientific and technological interest. The applications of these materials take advantage of the fact that they are very hard, refractory and that they have metallic properties. In this work, we have studied the influence of the heat treatment temperatures (400-1000°C) on the interaction between the titanium thin films and steel substrates. Steel substrates, 100C6 type (AFNOR norms), containing approximately 1 wt % of carbon, were coated at 200°C with titanium thin films by magnetron sputtering. The samples were characterized by X ray diffraction (XRD), Auger electron spectroscopy (AES) and scanning electron microscopy (SEM). Vikers micro-hardness measurements carried out on the annealed samples showed that the microhardness increases with annealing temperature, reaches a maximum (3500 kg/mm2), then decreases progressively. The growth of micro-hardness is due to the diffusion of the carbon, and to the formation of titanium carbide. However, the decrease of micro-hardness is associated to the diffusion of iron and the formation of iron oxide (Fe2O3). At higher temperatures, we note the formation of titanium oxide (TiO2). Description: AST Annales des Sciences et Technologie Thu, 01 Jan 2009 00:00:00 GMT https://dspace.univ-ouargla.dz/jspui/handle/123456789/6419 2009-01-01T00:00:00Z https://dspace.univ-ouargla.dz/jspui/handle/123456789/6423 Titre: CHOLINESTERASE AND TOXICITY IN SCHISTOCERCA GREGARIA BY CARBAMAT INSECTICIDE (FORSKÅL, 1775) Auteur(s): GHENABZIA I; HAMDI AISSA L; OULD EL HADJ M. D Résumé: The activity of acetylcholinesterase and the cardiac rhythm, studied at individuals female and male of Schistocerca gregaria exposed to Kuik 200 SL, an insecticide of the family of carbamates, are made at various exposure times and concentrations of the insecticide of 2g, 4g and 8g of Kuik 200 SL/l. An inhibition of cholinesterase activity is noted for the different doses of Kuik 200 SL. With a maximum inhibition at a dose of 8g of Kuik 200 SL/l, The cholinesterase activity is only 3,81±3,68 nmol/min/ml for the male individuals of S. gregaria and 5,6±5,98 nmol/min/ml for the individuals females. This inhibition of activity cholinesterasique few persists 24 hours after treatment. The exposure to Kuik 200 SL modifies significantly the cardiac rhythm whatever the dose and duration of exposure. It is perceptible that more the dose increases, the cardiac rhythm decreases. The action of different doses of Kuik 200 SL on the time of mortality of males and females of S. gregaria shows that the shortest time of mortality is observed at locusts treated at a dose of 8g of Kuik 200 SL/l. The male individuals of this locust die faster compared with the individual’s females. The Kuik 200 SL affects the rate of protein also the acetylcholinesterase specific activity according to the dose of the insecticide and the exposure time. It is noticed in view of the results that the low temperature is 18°C, has more effect after treatment on the activity of the acetylcholinesterase and the cardiac rhythm compared than a high temperature to 36°C. The Kuik 200 SL presents shorter time of mortality for the individuals of Schistocerca gregaria in 18°C, compared with the individuals in 36°C. Description: AST Annales des Sciences et Technologie Thu, 01 Jan 2009 00:00:00 GMT https://dspace.univ-ouargla.dz/jspui/handle/123456789/6423 2009-01-01T00:00:00Z