Decomposition dynamics of soybean residues in two soils of different fertility

The study objective was to evaluate the influence of the addition of soybeans residues on the chemical properties of Eutrudox and Hapludox soils. Soybean leaves and stems were incubated for 0-200 days. The statistical model used was a 5×4 factorial (plantxincubation period) with three replications. Soils without addition of plants were used as controls. Total Organic Carbon (TOC), Soluble Carbon (SC), Total Carbohydrates (TC), Humic Acid (HA), Fulvic Acid (FA) and Humification Rate (HR) were determined. Higher values of chemical attributes (TOC, SC and TC) were found in the Eutrudox soil than in the Hapludox soil and these values increased significantly (p<0.05) after 50 days of incubation in relation to the initial period. The TOC, SC and TC increased in soils amended with soybean plants when compared to controls without plants. HA and FA contents and HR were not affected by the addition of soybean residues. Maximum HA contents were found after 100 days and maximum FA contents and HR were found after 200 days incubation in both soils. It can be concluded that the addition of soybean residues increased the soil chemical properties when compared to the controls. © 2013 Academic Journals Inc.

User-producer interaction in the Brazilian oil industry: The relationship between petrobras and its suppliers of wet Christmas tree

The objective of this work is to analyze the importance of the user-producer interaction for the innovative process of the Brazilian oil industry from the 2000s. To do so, we selected two of the three providers installed in Brazil that produce the set of valves used in the oil wellhead to control its production, set which is called wet Christmas tree (WCT), the Norway's Aker Solutions and the American FMC Technologies. The results of this analysis indicate not only the development of the oil industry in Brazil is marked by a strategy of cooperative innovation, but they also reveal the importance of geographical proximity and direct cooperation, especially between the centers of engineering and research and development of companies. Furthermore, these partnerships are not limited to the adaptation of products to new needs, but they also include the development of new systems. © Universidad Alberto Hurtado, Facultad de Economía y Negocios.

Leaf anatomical traits are correlated with tree dominance in a Neotropical deciduous forest

Deciduous forests from the neotropics are one of the most endangered forest types in the world due to the exploitation of their natural resources by mankind. Many aspects of these ecosystems have been studied; however, there is a lack of information about leaf structure and the effects of tree dominance on their structural leaf patterns. In this article, we examine leaf anatomy and specific leaf areas (SLA) in 13 tree species differing in their dominance in a Dry Forest site in Central Brazil, relating leaf anatomical traits with phytosociological aspects. Leaf anatomical traits differed according to tree dominance: greater leaf thickness (achieved through greater thickness of the mesophyll), low values of SLA and bigger stomata were found for the most dominant species, whereas the less dominant species showed thinner leaves with high SLA, as well as numerous and small stomata. These responses suggest that tree dominance is an important indirect effect associated with vertical light availability in the forest. These strategies are probably related to the accomplishment of a high performance in carbon gain and water economy, given the distinction in irradiance that the leaves of different species are subject to in the dry forest. © 2013 Copyright The Royal Society of New Zealand.

Kinetic parameters for thermal decomposition of hydrazine

The propulsion of most of the operating satellites comprises monopropellant (hydrazine - N2H4) or bipropellant (monometilydrazine - MMH and nitrogen tetroxide) chemical systems. When some sample of the propellant tested fails, the entire sample lot shall be rejected, and this action has turned into a health problem due to the high toxicity of N2H 4. Thus, it is interesting to know hydrazine thermal behavior in several storage conditions. The kinetic parameters for thermal decomposition of hydrazine in oxygen and nitrogen atmospheres were determined by Capela-Ribeiro nonlinear isoconversional method. From TG data at heating rates of 5, 10, and 20 C min-1, kinetic parameters could be determined in nitrogen (E = 47.3 ± 3.1 kJ mol-1, lnA = 14.2 ± 0.9 and T b = 69 C) and oxygen (E = 64.9 ± 8.6 kJ mol-1, lnA = 20.7 ± 3.1 and T b = 75 C) atmospheres. It was not possible to identify a specific kinetic model for hydrazine thermal decomposition due to high heterogeneity in reaction; however, experimental f(α)g(α) master-plot curves were closed to F 1/3 model. © 2013 Akadémiai Kiadó, Budapest, Hungary.