921 research outputs found

    Correlações entre descritores de fruto de aceroleira em diferentes estádios de maturação.

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    O objetivo deste trabalho foi estimar as correlações entre descritores de frutos avaliados em acessos de aceroleira do Banco Ativo de Geromplasma (BAG) da Embrapa Semiárido

    Diversidade genética em acessos de aceroleira baseada em descritores físico-quimíco de frutos em diferentes estádios de maturação.

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    O presente trabalho objetivou estudar a diversidade dos últimos acessos introduzidos no BAG de aceroleira da Embrapa, conjuntamente com o germoplasma presente nas principais áreas tradicionais de cultivo

    Caracterização física e físico-química de acessos de mangueira do Banco de Germoplasma da Embrapa Semiárido.

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    O presente trabalho teve como objetivo caracterizar acessos de mangueira, baseando-se em atributos físicos e físico-químicos, visando ao fortalecimento do programa de melhoramento genético da cultura desenvolvido na Embrapa Semiárido

    Revealing the true impact of interstitial and substitutional nitrogen doping in TiO2 on photoelectrochemical applications

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    Application of photocatalysts that strongly absorb within the visible range is a common strategy to improve the efficiency of photoelectrochemical (PEC) systems; this may translate to high photocurrents, but it is not always the case. Here, we show that nitrogen doping enhances visible light absorption of TiO2; however, it does not necessarily result in improved PEC performance. Depending on the applied external potential, N-doping can improve, or degrade, PEC performance either under water oxidation conditions or via hole scavenging (Na2S/Na2SO3). In this work, we developed a holistic approach to evaluate the true impact of N doping in TiO2 on PEC performance. Interstitial and substitutional N doping are experimentally explored for the first time through a simple and novel PEC approach which complemented X-ray photoelectron analyses. Using this approach, we show that interstitial N doping of anatase TiO2 dominates up to 400 °C and substitutional doping up to ca. 600 °C, without rutile formation. This reveals that the bottleneck for doping higher N-concentrations in TiO2 is the direct transformation to thermodynamically favorable N-rich phases, such as TiN/Ti2N at 700 °C, inhibiting the formation of rutile phase. Transmission electron microscopy revealed that N doping proceeds mainly from the inner to the outer tube walls via nitridation and follows a preferential pathway from interstitial to substitutional doping. Direct PEC experimental evidence on visible light activation of N doped TiO2, and the location of interband states, showed acceptor levels of 1.0 eV for substitutional and 0.7 eV for interstitial doping above the TiO2 valence band maximum. In addition, due to O vacancies and Ti3+ species, donor levels below the conduction band minimum were also created. These levels act as trapping/recombination centers for charge carriers and, therefore, the gain in the visible range due to N doping does not translate to an improved PEC performance by these structural defects. Ultimately, we show that whilst there is a benefit of visible light absorption through N doping in TiO2, the PEC performance of the samples only surpasses pristine TiO2 at relatively high biasing (>0.3 V vs. Ag/AgCl)

    Rationales, rhetoric and realities:FIFA’s World Cup in South Africa 2010 and Brazil 2014

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    The 2010 FIFA World Cup was heralded by mainstream media outlets, the local organisers, the South African government and FIFA as an unequivocal success. The month-long spectacle saw South Africa take centre stage and host the world’s largest single sporting event. This occurred against a backdrop of rationales and promises made that the event would leave lasting legacies for all, in particular marginalised South Africans. The reality is quite different. In this article we consider the South African World Cup in the build up to Brazil 2014. We argue that the rationales and rhetoric are similar in both countries and suggest the reality for Brazil 2014 will be the same as South Africa 2010 in that the mega-event will be primarily funded by significant public investment, while the primary beneficiaries will be private capital and FIFA
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