20 research outputs found
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Using Backpropagation Networks for the Estimation of Aqueous Activity Coefficients of Aromatic Organic Compounds
Artificial Intelligence Lab, Department of MIS, University of ArizonaThis research examined the applicability of using a neural network approach to the estimation of aqueous activity coefficients of aromatic organic compounds from fragmented structural information. A set of 95 compounds was used to train the neural network, and the trained network was tested on a set of 31 compounds. A comparison was made between the results and those obtained using multiple linear regression analysis. With the proper selection of neural network parameters, the backpropagation network provided a more accurate prediction of the aqueous activity coefficients for testing data than did regression analysis. This research indicates that neural networks have the potential to become a useful analytical technique for quantitative prediction of structure-activity relationships
Importância do etanol na atenuação natural de águas subterrâneas impactadas por gasolina Importance of ethanol on natural attenuation of groundwater impacted by gasohol
Nesse estudo, foram avaliados os resultados de um experimento de derramamento controlado de gasolina brasileira em água subterrânea durante 6,5 anos de monitoramento. A exaustão do etanol, aos 32 meses de monitoramento, e a significativa redução de mais de 90% da massa máxima dos compostos BTEX dissolvidos no meio, aos 79 meses, associadas ao uso dos receptores de elétrons e acúmulo de seus subprodutos metabólicos, demonstraram a eficácia da atenuação natural monitorada para contaminações de águas subterrâneas sem riscos imediatos a receptores críticos. Constatou-se ainda que a biodegradação do etanol permitiu a formação de uma biobarreira natural que, após a sua completa degradação, acelerou a taxa de biodegradação dos BTEX e impediu o avanço da pluma destes contaminantes.<br>In this study, results of 6.5 years of a controlled release experiment with Brazilian gasoline in groundwater were evaluated. Ethanol exhaustion after 32 months and the significant dissolved BTEX mass reduction of more than 90% after 79 months, associated with the electron acceptors use and their metabolic byproducts accumulation, demonstrated the efficiency of monitored natural attenuation for groundwater contamination without immediate risk to receptors. Moreover, ethanol degradation provided a natural biobarrier formation that increased BTEX biodegradation rate and prevented the BTEX plume expansion