Geologia e litogeoquímica da formação serra geral nos estados de mato grosso e mato grosso do sul

The basalts of the Formação Serra Geral in Parana Basin in the Mato Grosso do Sul and Mato Grosso states cover an area of 180,000 km2. They rest on the Botucatu sandstones and they are recovered by the sedimentary rocks of Bauru and Caiuá Groups. The mineralogical composition of these rocks are plagioclase (40%-55%), clinopyroxenes (19%-40%; augite and pigeonite), opaque minerals (2%-10%; magnetite and ilmenite) and olivine (1.5%). Geochemical data show two different types of basalts, named ATi-Pitanga (2.6% < TiO2 < 4.2%; 396 ppm < Sr < 438 ppm) and BTi-Ribeira (1.7% TiO2 <2.4%, 246 ppm < Sr < 286 ppm). In general, ATi-Pitanga have gently higher La/Yb(n) (6,1 ± 1,5ppm) than those BTi-Ribeira (5.6 ± 1,7ppm). The geochemical differences between ATi-Pitanga and BTi-Ribeira probably are related to different degrees of partial melt of a same mantle source, or to different mantle sources. The field relations show that BTi-Ribeira is displaced towards the north-western margin of the Paraná Basin and the thickness of lava flows increases towards the Paraná Graben, suggesting that ATi-Pitaga overlies BTi-Ribeira.

Metabolismo de carboidratos não-estruturais em ruminantes

The carbohydrates provide 50 to 80% of the dry matter of grain and roughage and can be divided into structural (cellulose, hemicellulose) and non-structural (starch, pectin and sugars). The non-structural carbohydrates are primarily digested in the rumen and its dynamic process is a sequence for the supply of nutrients to the intestine. The quality and quantity of products resulting from ruminal fermentation are dependent on the type and activity of microorganisms in the rumen influenced by the type of food processing and that are subject of cereal grains that make up the diet. The NSC escape of rumen fermentation to be digested into glucose in the small intestine by pancreatic enzymes of origin (α-amylase) and intestinal mucosa (maltase and isomaltase). Starch is the most important energy supplier of cereals, which are important components of diets for intensive production of milk and meat.

Utilização do coque verde de petróleo da Petrobras em substituição parcial ao carvão mineral das misturas injetadas em altos fornos

The Petrobras produced green petroleum coke (GPC) is a carbon rich fuel, virtually ash-free, with low sulfur content, and is a fuel suitable to replace metallurgical coke in blast furnaces. The GPC was tested in a pulverized coal injection simulator built in the Volta Redonda research center. It presented a low burning efficiency due to low volatile material content and high substitution rate by the carbon content. The tests were carried out in blast furnaces with ≤ 50% Petrobras GPC in the coal blends. The injected coal/CVP mixtures produced no negative side effects in the blast furnace grinding systems, pneumatic conveying, or operating process. The mixture burning process inside the blast furnace showed a decrease in fuel consumption, with a significant reduction in metallurgical coke consumption. The industrial-scale tests of the GPC mixtures did not reach the 70% maximum for lack of the GPC feedstock, which is necessary to continue with standard coal mixtures.

Mudanças estruturais na agricultura brasileira, 1980-1998

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Efectos del alza del precio del petróleo en la competitividad de las exportaciones manufactureras de Centroamérica, México y la República Dominicana

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Interacciones intergubernamentales entre los impuestos sobre el petróleo y el gas y la protección ambiental

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La volatilidad de los precios del petróleo y su impacto en América Latina

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Gestión de la industria petrolera en período de altos precios del petróleo en países seleccionados de América Latina

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El alza del precio del petróleo y su impacto en los fletes marítimos de productos exportados por Chile en contenedores

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El Fondo de Estabilización de Precios del Petróleo (FEPP) y el mercado de los derivados en Chile

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Tendencias recientes del mercado internacional del petróleo

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Influência da irrigação, da densidade de plantio e da adubação nitrogenada nas características morfogênicas, estruturais e de produção do capim-tanzânia

This experiment was carried out to evaluate canopy height of guinea grass with 95% of photosynthetic active radiation interception and quantify the nitrogen fertilization influence and plants' density on the morphogenesis and structural characteristics of Tanzania grass. Four doses of N (0, 80, 160 e 320 kg.ha -1), were arranged with three plant densities (9, 25 and 49 plants.m -2), according to 4 × 3 completely randomized design, with three repetitions. Total dry matter (DM) accumulation throughout the experimental period was influenced by nitrogen fertilization and plants' density. In the rainy period, the higher nitrogen fertilization decreased the harvesting intervals, and consequently, increased the number of harvests. The rate of leaf appearance and the phyllochron were influenced only under nitrogen fertilization in the transition period of rainy and dry weather. Tanzania grass canopy height under 95% of light interception was positively influenced because of the plant densities in rainy period and transition period between rainy/drought and drought. Tanzania grass height under 95% of light interception presented variations along the evaluations and the values were higher (near 70 cm) in the rainy period, followed by transition period rain/drought and drought. © 2011 Sociedade Brasileira de Zootecnia.

Geologia e Caracterização Tecnológica do Minério de Manganês da Mina Córrego do Cocho, Itapira (SP)

The objects of this study are three manganese ore deposits and one mine derived from lateritic weathering of gondites (spessartine quartzites). These deposits are associated with Mn-rich garnet metasediments of the Itapira Group (Paleoproterozoic) and the reserves were estimated at approximately 2.0 × 10 6 tons with an average grade of 23% MnO 2. The ore minerals are cryptomelane, pyrolusite, lithiophorite, spessartine and psilomelane. Several crystal shapes and textural characteristics were identifi ed in this study, which are related to the degree of liberation, as confi rmed by heavy media separation method. In this study, we determined the main characteristics of the liberation of manganese, which is concentrated in the fi ne grain-size fraction and is lost during ore dressing. Therefore, the low average content of MnO 2 (28%) is due to this loss, whereas at grain size of minus 0.074 mm, contents near 40% MnO 2 were observed. This suggests that the ore can be used for manufacturing manganese sulphate fertilizers. A comparative study with the ore deposits located at Ouro Fino (MG), mainly with the Caneleiras mine, showed that higher degree of liberation occurs in the coarse grain-size fractions (0.84 to 0.074 mm with MnO 2 content of 38%). As a consequence, the ore can be used for manufacturing Fe-Si-Mn alloys.

Correlações entre características morfogênicas e estruturais em pastos de capim-braquiária

The analysis of both morphogenetic and structural characteristics of pasture allows us to understand the response patterns of the plant to the environment. Thus, this study was conducted to evaluate the associations between the morphogenetic and structural characteristics of Brachiaria decumbens under continuous grazing by cattle. The development of individual tillers in pastures was evaluated under two grazing management strategies during three seasons (winter, spring and summer). Pearson correlations between variables were estimated. The lengths of leaf and stem, number of tillers and leaves per tiller, rates of leaf appearance and elongation of leaf and stem of B. decumbens were positively correlated. There was a negative relationship between appearance and lifespan of leaves (r = -0.89). However, positive correlations between leaf appearance rate and number of tillers (r = 0.64) and between length of stem and leaf senescence rate (r = 0.63) were determined. The B. decumbens modifies its morphogenesis to better adapt to climate and grazing management.

Determinantes de la inversión en el sector petróleo y gas en la Argentina

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