Viabilidade de implantacao de aveia em pastagens estabelecidas de capim-elefante.

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As diversas faces dos embargos de declaração

- Disponível também na Revista de Processo: RePro, v. 30, n. 130, p. 11-18, dez. 2005

Pastagens consorciadas: procedimentos, técnicas e cuidados no estabelecimento.

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Study of an ethylic biodiesel integrated process: Raw-materials, reaction optimization and purification methods

No studies are reported on ethylic biodiesel integrated processes, considering raw materials, reaction optimization and product purification. The present study aims to: i) select key variables for experimental optimization of ethanolysis using a virgin vegetable oil; ii) perform an optimization study using a waste oil; and iii) evaluate the effectiveness of water free purification methods. Sunflower oil ethanolysis was conducted at different temperatures (30 - 80 degrees C), catalyst concentrations (0.3 - 2 wt.%), reaction times (0.5 - 4 h) and ethanol: oil molar ratios (2:1 - 12:1). Optimization experiments on waste oil ethanolysis were performed at different temperatures (30 50 C) and ethanol: oil molar ratios (6:1 - 12:1), during 1 h and using 1 wt.% catalyst. Quality parameters were measured according to EN 14214. A cation-exchange resin and a ceramic membrane were evaluated for water-free purification. Regarding sunflower oil ethanolysis, when successful, conversion ranged from 75.2 to 97.7 wt.%. Using both oils under optimized conditions (45 degrees C, 6:1 ethanol:oil molar ratio), a product with a very high purity (>98.0 wt.%) was obtained after water washing purification. The 0.1 mu m ceramic membrane was more effective than the cation-exchange resin, but it was not possible to obtain a good quality product using both methods

Challenging differential privacy: the case of non-interactive mechanisms

Best Student Paper AwardInternational audienceIn this paper, we consider personalized recommendation systems in which before publication, the profile of a user is sanitized by a non-interactive mechanism compliant with the concept of differential privacy. We consider two existing schemes offering a differentially private representation of profiles: BLIP (BLoom-and-flIP) and JLT (Johnson-Lindenstrauss Transform). For assessing their security levels, we play the role of an adversary aiming at reconstructing a user profile. We compare two inference attacks named single and joint decoding. The first one decides of the presence of a single item in the profile, and sequentially browses all the item set. The latter strategy decides whether a subset of items is likely to be the user profile, and browses all the possible subsets. Our contributions are a theoretical analysis and practical implementations of both attacks tested on datasets composed of real user profiles revealing that joint decoding is the most powerful attack. This also gives useful insights on the setting the differential privacy parameter $\epsilon$

UV photodecomposition of zinc acetate for the growth of ZnO nanowires

The thermal annealing of zinc precursors to form suitable seed layers for the growth of ZnO nanowires is common. However, the process is relatively long and involves high temperatures which limit substrate choice. In this study the use of a low temperature, ultra-violet (UV) exposure is demonstrated for photodecomposition of zinc acetate precursors to form suitable seed layers. Comparisons are made between ZnO nanowire growth performed on seed layers produced through thermal annealing and exposure to UV. The dependence of growth density and nanowire diameter on UV exposure time is investigated. Growth quality is confirmed with energy dispersive x-ray (EDX) and x-ray diffraction analyses. The chemical composition of the exposed layers is investigated with EDX and x-ray photoelectron spectroscopy (XPS). Atomic force microscopy (AFM) is utilized to investigate morphological changes with respect to UV exposure. The diameter and density of the resultant growth was found to be strongly dependent on the UV exposure time. UV exposure times of only 25–30 s led to maximum density of growth and minimum diameter, significantly faster than thermal annealing. EDX, XPS and AFM analyses of the seed layers confirmed decomposition of the zinc precursor and morphological changes which influenced the growth