The present work has focused on the application of the inverse-QSAR/QSPR problem for generating new structures of pesticides; this is in view of its extremely important and widespread use in several areas, particularly the agricultural field. For this reason, we implemented a methodology containing nine detailed successive steps that include a quantitative structure-activity/property relationship (QSAR/QSPR) study performed to develop a model that relates the structures of 190 pesticides compounds to their n-octanol-water partition coefficients (logk ow). We used the unique atomic signatures which represent the structures and acts as independent variables while the property (logk ow) as the dependent variable. The model was constructed using 130 molecules as training set, and predictive ability tested using 60 compounds. Modeling of logk ow of these compounds as a function of the signatures descriptors was established by multiple linear regression (MLR) using (LOO) cross-validation. As a result, a QSAR/QSPR equation with 14 atomic signatures was hereby obtained with a R 2 = 0.659273, Q 2 = 0.65617 and RMSE training = 0.930192, s = 1.37297 for the training set and in leave-one-out (LOO) cross-validation experiment set value, q 2 = 0.605676, RMSE LOO = 1.0936 respectively. In addition to all of the above, new structures have been generated for a range of pesticides that can be included as future search topics.

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The aim of our work is to study the response of the barley plant (Hordeum vulgare L.) to salt stress, at different NaCl concentrations (0, 50, 100, 150 and 250 mM) and follow its growth over time in the effect of salt stress. The control is based mainly on measurements of biometric parameters: length of the aerial and underground parts, fresh biomass, dry biomass and leaf area. The results clearly show the influence of salt stress on these parameters. The variety of barley, studied, showed good resistance to the phenomenon at concentrations not exceeding 150 mM salt. The study of the variance of the different parameters with ANOVA revealed no significant differences in the length of the ground aerial part and fresh biomass variations, the latter is very highly significant at a concentration greater than 150 mM of salt. Dry biomass showed no significance for concentrations less than 150 mM, while it is very highly significant for 250 mM NaCl. With regard to the leaf surface, the variations are significant for less than 100 mM and very highly significant beyond 250 mM of salt.

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The present work is to develop software to predict the value yield and the distribution coefficient in the process of liquid-liquid extraction of components of a mixture, from mathematical models expressing these entities, based on equations equilibrium between liquid-liquid phases, and predict the conditions under which the extraction operation is favorable, unfavorable or impossible to realize, by studying the variation of the entities cited, based on the parameters influencing the extraction, which are: initial concentrations, rate of solvent and pH, in the case of a simple extraction (extraction of neutral products) or when it is reactive (extraction of complex acids or bases) for one or more components.The programming language used is "Delphi" which is a very powerful oriented object programming under Windows.

In Algeria, much progress has been made in implementing efficient and less expensive wastewater treatment processes. Phytodepuration is one of the processes that have shown their effectiveness in this area, because of its simplicity and low costs. The only experiment in Algeria is the pilot station located in the city of Temacine. This station is designed to treat 15 m 3 per day of urban wastewater. This work aims to assess the effectiveness in eliminating nitrogen pollution by phytodepuration and to verify whether it is well adapted to the studied region. For a period of one year, samples of raw and treated wastewater were collected and analyzed. The purification yields of the different pollutants were calculated. The results show that purification performance is good and exceeds 80% for all measured parameters. With regard to nitrogen pollution, the abatement rates reached 83.06% for ammonium, 70.44% for nitrites, 81.92% for nitrates and 83.20% in terms of total Kjeldahl nitrogen. These performances meet the standards recommended by the Algerian legislation. The water produced is of clean quality and can be reused in irrigation. In addition to its effectiveness in reducing nitrogen pollution, phytodepuration treatment seems to be very beneficial and well adapted to the study area, as the absence of noise, bad odors and the good coverage of the basin by flowers and plants, has largely allowed to preserve the environment in this region and to keep its tourist aspect. These results are encouraging to develop the use of the system in other localities.