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Missio R.L.,Federal University of Santa Maria | Brondani I.L.,Federal University of Santa Maria | Filho D.C.A.,Federal University of Santa Maria | da Silveira M.F.,Federal University of Santa Maria | And 2 more authors.
Revista Brasileira de Zootecnia | Year: 2010

This study was developed to evaluate the ingestive behavior of beef cattle finished in feedlots with different concentrate levels in the diet. Sixteen bulls fed 22, 40, 59, or 79% of concentrate in the diet were assigned to a complete randomized design, with four replicates each. The supplied diets were isoproteic and the roughage used was corn silage. Data collection was carried out during the finishing period, with a total of six days. The time given to food intake, rumination, the number of bouts per meal and neutral detergent fiber rumination efficiency decreased linearly as the concentrate levels in the diet increased. Idle time increased linearly accordingly to the increment of concentrate in the diet. The animals have greater feed intake and rumination efficiency when fed higher levels of concentrate (79%). © 2010 Sociedade Brasileira de Zootecnia.

Del Prado Z.,UFG | Gonalves P.B.,Pontifical Catholic University of Rio de Janeiro | Padoussis M.P.,McGill University
International Journal of Mechanical Sciences | Year: 2010

In this work, Donnell's non-linear shallow shell equations are used to study the dynamic instability of perfect simply supported orthotropic cylindrical shells with internal flowing fluid and subjected to either a compressive axial static pre-load plus a harmonic axial load or a harmonic lateral pressure. The fluid is assumed to be non-viscous and incompressible and the flow, isentropic and irrotational. An expansion with eight degrees of freedom, containing the fundamental, companion, gyroscopic, and four axi-symmetric modes is used to describe the lateral displacement of the shell. The Galerkin method is used to obtain the non-linear equations of motion which are solved by the RungeKutta method. A detailed parametric analysis clarifies the influence of the orthotropic material properties on the non-linear buckling and vibration characteristics of the shell. Numerical methods are used to identify the effect of the fluid flow and applied loads control parameters on the bifurcations and stability of the shell motions. © 2010 Elsevier Ltd. All rights reserved.

Andre R.S.,Federal University of Sao Carlos | Paris E.C.,University of Sao Paulo | Gurgel M.F.C.,UFG | Rosa I.L.V.,Federal University of Sao Carlos | And 4 more authors.
Journal of Alloys and Compounds | Year: 2012

This paper reports the synthesis of Eu-doped hydroxyapatite (HA:Eu) resulting in particles with nanorod diameters from 9 to 26 nm using the microwave hydrothermal method (HTMW). Eu3+ ions were used as a marker in the HA network by basic hydrolysis followed by the HTMW treatment. The crystalline HA:Eu nanorod nature in a short-range order was detected by photoluminescence (PL) measurements from Eu3+ emission into the HA matrix. Thus, was possible to verify that HA crystallization is favored in a short structural order when the HTMW treatment time was increased from 0 to 40 min and that the Eu3+ substitution in the HA lattice is site-selective. © 2012 Elsevier B.V. All rights reserved.

Ferreira D.A.,Federal University of Goais | Carneiro M.A.C.,UFG | Saggin Jr. O.J.,Embrapa Agrobiologia
Revista Brasileira de Ciencia do Solo | Year: 2012

The alterations in the communities of arbuscular mycorrhizal fungi (AMF) induced by changes in land use and different agricultural uses are still insufficiently studied, particularly in the Cerrado biome. This study evaluated how human interference by management and land use change affect the AMF density and diversity in a Cerrado Oxisol. The study evaluated five areas: Riparian Forest (MC), Riparian Forest Edge (BM), Pasture (Past), no-till monoculture (PD) and Riparian Deforested Area (AD). In each area, 20 plots of 250 m2 were marked. Within each plot, 10 subsamples were randomly collected to form a composite soil sample. The density and diversity of AMF spores, by morphological characteristics, were determined for each composite sample. In the PD and AD areas, the density of recovered spores and mycorrhizal colonization were lower than in the other areas due to the low density of living plants. The AMF families with highest abundance in the study areas were Acaulosporaceae, Glomeraceae and Gigasporaceae, the first two dominant in the areas with leass anthropogenic influence MC and BM. The most frequent AMF species were Acaulospora scrobiculata, Glomus macrocarpum and Acaulospora tuberculata, of which the first two appeared in all areas and the third was absent only in PD. These species have great capacity to adapt to changing environments. The occurrence of the species Acaulospora rehmii, Acaulospora sp.3, Glomus etunicatum, Glomus tortuosum, Glomus sp.1, Gigaspora sp.2 and Scutellospora heterogama was low, and were recovered in only one of the study areas. The area with highest density and species occurrence was Past with 414 spores (individuals) and 11 AMF species. The highest and lowest Shannon diversity (H') index were calculated for Past and BM, respectively. Principal component analysis indicated the formation of three groups, the first with MC and BM, the second with PD and AD and the third with only Past. It was concluded that land use changes modify the AMF community, which may increase spore density and diversity, as in the case of Pasture, or reduced, in the case of deforestation.

Pacheco L.P.,Federal University of Piaui | Barbosa J.M.,Federal University of Goais | Leandro W.M.,UFG | de Almeida Machado P.L.O.,Embrapa Arroz e Feijao | And 3 more authors.
Revista Brasileira de Ciencia do Solo | Year: 2011

The cover crops in no-till system can contribute to the formation of mulch and nutrient cycling to annual crops in succession. The objective of this study was to evaluate biomass production and nutrient cycling of cover crops sown in the second growing season, in crop rotation after upland rice and soybean, in no-tillage and conventional tillage systems, on a Red Latassol of Rio Verde, state of Goiás, from April 2008 to April 2010. The experiment was evaluated in randomized strips, in a 5 x 6 factorial design, with four replications. In the horizontal strips two soil management systems (after three years of no-tillage and conventional systems) were evaluated and the cover crops in the vertical strips. Biomass and ground cover and nutrient cycling rates were only evaluated in the no-till treatments, in a 5 x 6 factorial arrangement, where the plots were subdivided, corresponding to six harvest dates of dried biomass 0, 15, 30, 60, 90 and 120 days after cutting of the cover crops. The following cover crops were sown in the second growing season: Brachiaria ruziziensis, Pennisetum glaucum and B. ruziziensis + Cajanus cajan and a fallow treatment as reference. Biomass production and the rates of soil cover and nutrient accumulation and release by cover crops as well as rice and soybean yield were evaluated. B. ruziziensis and B. ruziziensis + C. cajan performed best in biomass production, ground cover and nutrient accumulation at the end of the cover crops. The nutrients N and K had the highest concentration in the biomass, and the highest nutrient release to the soil was observed for K and P. The highest rice yield was observed when grown in no-tillage on crop residues of P. glaucum and B. ruziziensis, while soybean yields did not differ in the treatments.

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