Universidade Federal de Santa Maria

About: Universidade Federal de Santa Maria is a education organization based out in Santa Maria, Brazil. It is known for research contribution in the topics: Population & Context (language use). The organization has 21178 authors who have published 35632 publications receiving 371665 citations.

Antioxidant protection of gallic acid against toxicity induced by Pb in blood, liver and kidney of rats

Abstract: The effect of the antioxidant gallic acid (GA) on Pb toxicity in blood, liver and kidney was investigated in the present study. Rats Wistar received Pb nitrate (50 mg/Kg/day, i.p., 5 days) followed by GA (13.5 mg/Kg, p.o., 3 days) or a chelating agent (EDTA, 55 mg/Kg, i.p.). As result, Pb decreased body weight, hematocrit and blood δ-aminolevulinic acid dehydratase (ALA-D) activity. In addition, high Pb levels were observed in blood and tissues, together with increased (1) lipid peroxidation in erythrocytes, plasma and tissues, (2) protein oxidation in tissues and (3) plasma aspartate transaminase (AST) levels. These changes were accompanied by decreasing in antioxidant defenses, like superoxide dismutase (SOD) activity in tissues and catalase (CAT) activity and reduced glutathione (GSH) in liver. GA was able to reverse Pb-induced decrease in body weight and ALA-D activity, as well as Pb-induced oxidative damages and most antioxidant alterations, however it did not decrease Pb bioaccumulation herein as EDTA did. Furthermore, EDTA did not show antioxidant protection in Pb-treated animals as GA did. In conclusion, GA decreased Pb-induced oxidative damages not by decreasing Pb bioaccumulation, but by improving antioxidant defenses, thus GA may be promising in the treatment of Pb intoxications.

Eficiência da escarificação mecânica e biológica na melhoria dos atributos físicos de um latossolo muito argiloso e no incremento do rendimento de soja

Abstract: A compactacao e uma das principais causas de decrescimo da produtividade dos solos agricolas. A escarificacao mecânica tem sido sugerida para reduzir a compactacao do solo em areas sob sistema de semeadura direta consolidada. Outra opcao para aliviar a compactacao e o uso de plantas de cobertura com sistema radicular pivotante e bem desenvolvido, como o nabo-forrageiro, com capacidade de crescer em camadas compactadas, formar bioporos estaveis e melhorar os atributos fisicos do solo. O objetivo deste trabalho foi avaliar a eficiencia do metodo mecânico (escarificador) e do metodo biologico (nabo-forrageiro) de descompactacao do solo, ou de ambos associados, em promover a melhoria dos atributos fisicos de um Latossolo de textura muito argilosa e o rendimento de graos da cultura da soja manejada sob semeadura direta. Os tratamentos utilizados foram: aveia-preta em semeadura direta (SD-Av), consorcio de nabo-forrageiro e aveia-preta em semeadura direta (SD-Nb+Av), aveia-preta em solo escarificado (ESC-Av) e consorcio de nabo-forrageiro e aveia-preta em solo escarificado (ESC-Nb+Av). Foram avaliadas a densidade, macroporosidade, microporosidade e porosidade total do solo nas camadas 0-0,05; 0,05-0,10; 0,10-0,15; e 0,15-0,20 m, resistencia do solo a penetracao, umidade gravimetrica e infiltracao de agua no solo, no momento do pleno florescimento da soja. Alem disso, foram determinadas a producao de materia seca das plantas de cobertura de solo de inverno e o rendimento de soja no verao. Os tratamentos nao afetaram significativamente a densidade do solo em nenhuma das camadas avaliadas, no entanto os tratamentos SD-Nb+Av e ESC-Nb+Av duplicaram os valores de macroporosidade do solo na media da camada 0-0,20 m, com efeitos mais pronunciados nas camadas mais superficiais do solo. Os tratamentos SD-Nb+Av e ESC-Nb+Av reduziram a resistencia do solo a penetracao em relacao ao tratamento SD-Av, enquanto o tratamento ESC-Av teve comportamento intermediario. Os tratamentos SD-Nb+Av e ESC-Nb+Av aumentaram, em media, 46,6 % a lâmina de agua infiltrada em relacao aos tratamentos SD-Av e ESC-Av. O maior rendimento de graos de soja foi observado no tratamento ESC-Nb+Av (3,73 Mg ha-1), que nao diferiu significativamente do SD-Nb+Av (3,49 Mg ha-1). A escarificacao mecânica do solo teve efeito temporario, e nao foram constatadas melhores condicoes fisicas do solo apos nove meses, com excecao do aumento da porosidade total e macroporosidade do solo na camada 0-0,05 m. Por outro lado, a escarificacao biologica aumentou a macroporosidade do solo, diminuiu sua resistencia a penetracao e melhorou a infiltracao de agua. A escarificacao mecânica foi uma alternativa eficiente em melhorar as condicoes fisicas do Latossolo textura muito argilosa quando associada a escarificacao biologica, que preveniu a reconsolidacao do solo.

Formation energy of native defects in BN nanotubes: an ab initio study

Abstract: Electronic and structural properties of several charge states of vacancies, antisites and carbon substitutional impurities in a (10, 0) BN nanotube are investigated through density functional theory calculations. The formation energies indicate that neutral and simply charged states occur in the range of allowable electronic chemical potential. For carbon substitutional impurities, the most probable states are, besides the neutrals, the positively charged state for carbon at a boron site (CB+), and the negatively charged state for carbon at a nitrogen site (CN−). The charge compensation between neighbouring pairs of CB+ and CN− defects is suggested to explain the successful experimentally obtained boron carbonitride nanotubes. Vacancies always present high formation energies. The neutral and positively charged states of the nitrogen antisite show low formation energies. The calculated formation energies for all defects studied here can be interpreted as due to two main effects: a tendency to recover the number of electrons of the defect-free BN nanotube and the screening effects due to the perturbative potential of the defects.

Distribuição temporal e espacial de anuros em área de Pampa, Santa Maria, RS

Abstract: The present study aimed to determine the richness, occurrence constancy, reproductive modes, standard of abundance distribution, season of vocalization and to test correlation among climatic variables and activity of vocalization of anurans in a region of the Pampa Biome, Santa Maria, Rio Grande do Sul State. During the period of November/2001 to October/2002 monthly collections were carried out utilizing the ‘survey at breeding site’ method and examination of specimens kept in the Colecao Herpetologica do Setor de Zoologia da Universidade Federal de Santa Maria (ZUFSM). The occurrence of 25 species of anurans was recorded. The anurofauna recorded represents 30% of the species known to occur in Rio Grande do Sul, and comprises species generally associated with grasslands in this state and neighboring countries. Four reproductive modes were recorded: mode 1 (14 species; 58.3%); mode 11 and 30 (9 species; 37.5%) and mode 24 (1 species; 4.2%). The low diversification of reproductive modes is likely related to the homogeneity of the grassland habitat. Most species were constant or accessory in the study area and the species abundance distribution patterns fit in the Broken Stick and Log-normal models, characterized by homogeneity of species abundance distribution. Most species showed great plasticity in habitat, but few were plastic in vocalization sites use. There was a weak positive correlation between species richness and precipitation. There was also a weak positive correlation between the abundance of species calling activity and maximum average temperatures. These correlations indicated that, in the study area, the abundance of calling males is more affected by the temperature, and species richness is more affected by precipitation, despite the fact that significantly higher species richness occurs during the hottest period of the year. These results showed that the climatological variables examined were not enough to explain the seasonal occurrence of species, thus the influence of other environmental variables merit to be tested in future studies.