181 research outputs found

    Bio-based substances from urban waste as auxiliaries for solar photo-Fenton treatment under mild conditions: optimization of operational variables

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    The use of soluble bio-based organic substances (SBO) obtained from urban wastes to expand the pH region where the photo-Fenton process can be applied has been investigated in this study. For this purpose, a mixture of six pollutants, namely acetaminophen, carbamazepine, amoxicillin, acetamiprid, clofibric acid and caffeine, at an initial concentration of 5 mg L−1 each, has been employed. Surface response methodology, based on the Doehlert matrix, has shown to be a useful tool to determine the effect of pH (in the range 3–7), concentration of SBO (15–25 mg L−1) and iron (2–6 mg L−1) on the performance of the photodegradation of the studied pollutants, measured by their half-life. Results indicate that, at high SBO concentration, the optimum pH shifts in most cases to a higher value (between 3 and 4) and that a significant loss of efficiency of the process was only observed at pH values above 5. An iron concentration of 4–5 mg L−1 and an amount of SBO of 19–22 mg L−1 have been determined to be the optimal conditions for the degradation of most of the studied pollutants at pH = 5.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

    Influência do preparo do solo, sistema de plantio e porta-enxerto no crescimento de tangerineira 'tangor murcott' em Tabuleiro Costeiro da Bahia - 2ª etapa.

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    Na Bahia, 80% da área citrícola encontra-se na Grande Unidade de Paisagem Tabuleiros Costeiros, em propriedades de até dez hectares (agricultura familiar). Objetiva-se um modelo de manejo que possibilite sustentabilidade, menor relação custo/benefício e maior produtividade de pomares cítricos especialmente destinados a essas propriedades. O experimento foi instalado na Fazenda Lagoa do Coco, município de Rio Real, Litoral Norte do Estado da Bahia, em um Argissolo Amarelo Coeso. O delineamento experimental é inteiramente casualizado, no esquema de parcelas sub-subdivididas no espaço, com seis repetições. Nas parcelas constam dois sistemas de preparo do solo: convencional, isto é, aração a 0, 25 m de profundidade, e aração seguida de subsolagem nas linhas de plantio a 0,50 m de profundidade; nas subparcelas constam dois sistemas de plantio: convencional, isto é, plantio de mudas, e semeadura e enxertia no local definitivo; nas sub-parcelas constam cinco porta-enxertos com tangerineira tangor ?Murcott?: limoeiro ?Cravo?, limoeiro ?Volkameriano?, tangerineira ?Sunki Tropical?, tangerineira ?Cleópatra? e híbrido ?TSK x TRENG 256?. Observou-se que o crescimento das plantas originárias da semeadura do porta-enxerto cítrico no local definitivo é superior ao daquelas originárias de mudas (plantas da mesma idade, 34 meses), independentemente do preparo do solo e da combinação copa/porta-enxerto

    Resistência de genótipos de tomateiro a Bemisia tabaci mediada por tricomas glandulares e acilaçúcares.

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    Foram avaliados genótipos de tomateiro oriundos do cruzamento de Solanum lycopersicum L e Solanum pimpinellifolium L visando encontrar fontes de resistência à mosca-branca.Suplemento. Trabalho apresentado no 52. Congresso Brasileiro de Olericultura, Salvador, 2012

    Interação de pireno e fenantreno com argilas em suspensão.

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    O objetivo desse trabalho é investigar a formação de micelas e ligação entre os HPA e as argilas

    O(d,d)-invariance in inhomogeneous string cosmologies with perfect fluid

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    In the first part of the present paper, we show that O(d,d)-invariance usually known in a homogeneous cosmological background written in terms of proper time can be extended to backgrounds depending on one or several coordinates (which may be any space-like or time-like coordinate(s)). In all cases, the presence of a perfect fluid is taken into account and the equivalent duality transformation in Einstein frame is explicitly given. In the second part, we present several concrete applications to some four-dimensional metrics, including inhomogeneous ones, which illustrate the different duality transformations discussed in the first part. Note that most of the dual solutions given here do not seem to be known in the literature.Comment: 25 pages, no figures, Latex. Accepted for publication in General Relativity and Gravitatio

    Theory of continuum percolation III. Low density expansion

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    We use a previously introduced mapping between the continuum percolation model and the Potts fluid (a system of interacting s-states spins which are free to move in the continuum) to derive the low density expansion of the pair connectedness and the mean cluster size. We prove that given an adequate identification of functions, the result is equivalent to the density expansion derived from a completely different point of view by Coniglio et al. [J. Phys A 10, 1123 (1977)] to describe physical clustering in a gas. We then apply our expansion to a system of hypercubes with a hard core interaction. The calculated critical density is within approximately 5% of the results of simulations, and is thus much more precise than previous theoretical results which were based on integral equations. We suggest that this is because integral equations smooth out overly the partition function (i.e., they describe predominantly its analytical part), while our method targets instead the part which describes the phase transition (i.e., the singular part).Comment: 42 pages, Revtex, includes 5 EncapsulatedPostscript figures, submitted to Phys Rev

    Femmes et hommes face aux grossesses non prévues au Maroc et au Sénégal

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    Cet article étudie la manière dont les femmes ou les couples gèrent les grossesses non prévues dans les capitales du Maroc et du Sénégal (Rabat et Dakar), deux pays soumis à des règles strictes en matière de sexualité des célibataires. Nous analysons les logiques sociales et individuelles qui prévalent à l'annonce d'une grossesse inattendue et la manière dont se prennent les décisions qui vont aboutir à la poursuite de cette grossesse ou à son interruption. Nous nous basons sur des données qualitatives tirées d'un programme financé par l'Union Européenne entre 2005 et 2009, sur l'usage de la contraception d'urgence dans les villes africaines. Nos résultats montrent qu'en dépit de programmes de planification familiale plus performants dans leur pays, les femmes de Rabat vivent leur entrée en sexualité dans des conditions difficiles. Si à Dakar la chasteté avant le mariage est prônée, le non-respect de cette règle entraîne des sanctions beaucoup moins sévères qu'au Maroc. Le choix de l'avortement en cas de grossesse non prévue évolue avec le cycle de vie des individus et selon le stade de la relation. Une pratique envisageable à un moment donné, ne l'est plus forcément à d'autres moments de la relation. Enfin, dans les deux villes, nos données révèlent une forte implication des familles dans la gestion de la formation des couples et de leur fécondité. Cette tendance apparaît cependant plus exacerbée au Maroc où les familles se mobilisent parfois âprement pour obliger ou interdire un avortement
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