4,906 research outputs found

    Mais de 170 cultivares transgênicas são disponibilizadas no mercado de sementes do Brasil para a safra 2011/12.

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    Rhodolith bed structure along a depth gradient on the northern coast of bahia state, brazil

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    O objetivo deste estudo foi determinar a estrutura de um banco de rodolitos ao longo de um gradiente de profundidade na plataforma em frente à cidade de Salvador, nordeste brasileiro. Foram analisadas as dimensões, a forma e composição das algas calcárias dos rodolitos, bem como a vitalidade, densidade e flora associada ao banco, em três profundidades: 5, 15 e 25 m. As amostras foram obtidas por meio de mergulho autônomo no verão de 2007. Cinco espécies de algas calcárias formadoras de rodolito foram identificadas: Sporolithon episporum, Lithothamnion brasiliense, Lithothamnion superpositum, Mesophyllum erubescens e Lithophyllum sp. A forma de crescimento incrustante e a forma esférica foram predominantes em todas as profundidades. Houve uma redução da dimensão e vitalidade dos rodolitos e um aumento da densidade com a profundidade. Cinqüenta e seis espécies de macroalgas foram encontradas como flora associada aos rodolitos. A profundidade mais rasa apresentou os maiores valores de biomassa e número de espécies de macroalgas. Esses resultados, associados com outras descrições recentes de bancos de rodolitos, indicam que o padrão estrutural desses bancos no Brasil, ao longo de gradientes de profundidade, pode estar relacionado a uma combinação da extensão e da inclinação da plataforma continental.The aim of this study was to determine the structure of a rhodolith bed along a depth gradient of 5 to 25 m in the shelf in front of Salvador City, a region of northeastern Brazil. The dimensions, morphology and coralline algae composition of the rhodoliths were analyzed, as well as the vitality, density, and associated flora of the bed at three depths: 5, 15 and 25 m. Samples were obtained by SCUBA divers in summer 2007. Five rhodolith-forming taxa were identified: Sporolithon episporum, Lithothamnion brasiliense, Lithothamnion superpositum, Mesophyllum erubescens, and Lithophyllum sp. The encrusting growth form and the spherical shape were predominant at all depths. Rhodolith dimensions and vitality decreased and the density increased from the shallow to the deepest zones. Fifty-six macroalgal species were found as rhodolith-associated flora. The shallower depth presented higher values for macroalgal biomass and number of species. These results associated with other recent rhodolith bed descriptions indicate that the pattern of Brazilian rhodolith bed structure along depth gradients may be related to a combination of the extent and slope of the continental shelf

    Photocatalytic reduction of levulinic acid using thermally modified niobic acid

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    After the discovery that commercial niobic acid (H0) is able to reduce the levulinic acid in value added molecules, H0 was thermally treated at 200 °C, 400 °C, and 600 °C, generating the niobium oxides H1, H2 and H3 and the photocatalytic improvement towards reduction was investigated. Although the higher temperatures significantly decreased the specific surface area, it was important to remove surface hydroxyl groups and create the T and TT-Nb2O5 phase mixture in H3 which were responsible for its best performance (36.4% of conversion and almost 99% of selectivity for reduced products). To further improve the H3 photoactivity, an identical synthesis was performed in H2 flow to produce oxygen vacancies in the structure of the new photocatalyst (H3OV). This simple modification method increased ∼7% of products yield, which is the best photocatalytic result obtained for pure niobium oxides so far, and proved that it is possible to significantly increase photocatalytic performance without laborious modifications. The electronic and structural differences between H3 and H3OV were investigated by XRD Rietveld refinement, EPR, HR-TEM, DRS and SAED analyses

    Sistema de produção de milho safrinha de alta produtividade: safras 2008 e 2009.

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    Caracterização do cultivo de milho safrinha de alta produtividade em 2008 e 2009.

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    O termo milho safrinha é empregado para o cultivo de milho de sequeiro semeado de janeiro a abril, após a colheita da cultura de verão. Para caracterizar os sistemas de produção de altas produtividades de milho safrinha foram coletados dados referentes a 1.138 lavouras que obtiveram produtividade acima de 5.000 kg ha-1, nos estados da região Centro-Oeste, em São Paulo e no Paraná. Embora tenham sido constatados rendimentos superiores a 8.000 kg ha-1 em todos os estados produtores de milho safrinha, a maior frequencia é de lavouras com rendimentos entre 5.000 e 7.000 kg ha-1. Nessas lavouras, predominou o plantio de híbridos simples e de ciclo precoce, no sistema plantio direto, com o milho sendo implantado no mês de fevereiro e cultivado geralmente após a soja. Em São Paulo e no Paraná, predominam o uso do espaçamento convencional, enquanto que nos estados da região Centro-Oeste a utilização de espaçamento reduzido é maior, especialmente em Goiás. A população de plantas variou de 45 a 65 mil plantas por hectare, com maior frequência no uso de 50 a 55 mil plantas por hectare. Cerca de 90% das lavouras receberam tratamento químico com fungicidas para o controle de doenças. O número de aplicações de inseticidas variou de zero até quatro aplicações, sendo mais frequente duas e três aplicações

    A pipeline to study structural interactions among Spodoptera frugiperda serine proteinases and plant proteinase inhibitors.

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    We propose here a computational biology pipeline to identify and analyze possible structural determinants that could explain some level of insensitivity by S. frugiperda serine proteinases (SPs) against plant PIs observed in a real time PCR experiment.GA 330

    Avaliação dos impactos econômicos de quatro forrageiras lançadas pela Embrapa.

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    Dominance of photo over chromatic acclimation strategies by habitat-forming mesophotic red algae

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    Funding was provided by a Leverhulme Trust Research Project grant no. (RPG-2018-113) to H.L.B., G.A.T. and I.D.W.S., an Engineering and Physical Sciences Research Council grant (EP/L017008/1) to G.A.T. and I.D.W.S., and a São Paulo Research Foundation (FAPESP) individual grant (#2016/14017-0) to G.H.P.-F.Red coralline algae are the deepest living macroalgae, capable of creating spatially complex reefs from the intertidal to 100+ m depth with global ecological and biogeochemical significance. How these algae maintain photosynthetic function under increasingly limiting light intensity and spectral availability is key to explaining their large depth distribution. Here, we investigated the photo- and chromatic acclimation and morphological change of free-living red coralline algae towards mesophotic depths in the Fernando do Noronha archipelago, Brazil. From 13 to 86 m depth, thalli tended to become smaller and less complex. We observed a dominance of the photo-acclimatory response, characterized by an increase in photosynthetic efficiency and a decrease in maximum electron transport rate. Chromatic acclimation was generally stable across the euphotic-mesophotic transition with no clear depth trend. Taxonomic comparisons suggest these photosynthetic strategies are conserved to at least the Order level. Light saturation necessitated the use of photoprotection to 65 m depth, while optimal light levels were met at 86 m. Changes to the light environment (e.g. reduced water clarity) due to human activities therefore places these mesophotic algae at risk of light limitation, necessitating the importance of maintaining good water quality for the conservation and protection of mesophotic habitats.Publisher PDFPeer reviewe
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