Transporte jejunal eletrogênico da glicose em ratos com deficiência de niacina.

The active electrogenic absorption of glucose was studied in 12 niacin deficient rats using a method for measuring changes in transmural potential difference across jejunal mucosa. The glucose was infused in 6 different concentrations (2.5; 5.0; 10.0; 20.0; 50.0 and 100.0 mM/L) at a constant rate of 1.7 ml per minute. The apparent kinetic parameters (Km and Pdmax) of active electrogenic transport were obtained graphically from curves of glucose transfer potentials. The results were compared with that obtained in a control group. The curve of glucose transfer potential in niacin deficient group was significantly lower than that of the control group. The apparent Km of niacin deficient group was greater than in the control group (16.1 x 12.7 mM/L). Furthermore, the Pdmax of the deficient group was lower than that of the control group (12.5 x 19.4 mV). The results showed that in niacin deficiency occurs a decreasing of the active electrogenic glucose absorption. One of the possible interpretation of the differences in the kinetic characteristics of electrogenic glucose transport would be a depleted energy supplement for the active transport in the enterocyte of the niacin deficient rats.

Efeito da calagem e sulfato de amônio no algodão. I - Transporte de cátions e ânions no solo

Applying lime on the soil surface in soils managed under no-tillage has caused an excess of basic cations in the most superficial layers of the soil profile. On the other hand, subsoil acidity is considered a constraint to the development of deep plant roots. The objective of this study was to evaluate Ca 2+, Mg 2+, NO 3- and SO 4 2- leaching in the soil profile as affected by liming and top dressing nitrogen fertilization in cotton, grown with straw cover on the soil surface. Cotton plants (Gossypium hirsutum) were grown for 60 days in PVC columns filled with a Distroferric Red Latosol (sand loam Rhodic Oxisol) with liming applied over the straw on the soil surface, incorporated liming 0-20 cm deep, or without liming. Nitrogen was applied at rates of 0, 50, 100 and 150 kg ha -1 as ammonium sulfate. The PVC columns were set up in layers of 0-5, 5-10, 10-20, 20-30 and 30-30 cm, totaling 15.71 dm 3. The ammonium sulfate application caused intense leaching of SO 4 2- in the soil, irrespective of the lime application method. Liming increased the concentration of NO 3 in the 0-20 cm soil layer, whereas the correction of the soil acidity did not affect the NO 3- concentration in the 30-50 cm soil layer. The influence of ammonium sulfate on Ca 2+ leaching below 20 cm was only observed in the soil with incorporated lime. Nitrogen application resulted in extensive Mg 2+ leaching from the soil, regardless of the lime application method. In the soil layer below 30 cm, SO 4 2- presented a higher correlation than NO 3- in the formation of ionic pairs with Ca 2+ and Mg 2+.

Enxertia e água de irrigação carbonatada no transporte de 15N e na produção do tomateiro

The effects of CO2 application through irrigation water, and of grafting in transport of 15N and in the tomato production, were studied. These treatments were arranged in a 2 x 2 factorial scheme (with and without CO2 in irrigation water and grafted and non-grafted tomato), in a completely randomized design, with four replications. The injection of CO2 into the water began at 34 days after transplant of seedlings (DAT) and continued for all irrigations. The application of the sulfate of ammonium with abundance in atoms of 15N of 3.13% in plants destined to analysis was done at 45 DAT when the plants were in the middle of fructification. After 14 days of fertilizer (15N) application the plants were harvested, washed, dried and sent for analysis of 15N in plant tissue. The results demonstrated that CO2 and the grafting did not alter the transport of 15N in the plant. The production of commercial fruits was larger when CO2 was applied in water.

El impuesto sobre circulación de mercaderías y servicios de transporte (ICMS) como instrumento económico para la gestión ambiental: el caso de Brasil

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El desarrollo sostenible en América Latina y el Caribe: tendencias, avances y desafíos en materia de consumo y producción sostenibles, minería, transporte, productos químicos y gestión de residuos. Informe para la decimoctava sesión de la Comisión para el Desarrollo Sostenible de las Naciones Unidas

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Concentración en los servicios de líneas regulares: causas del proceso y sus efectos sobre el funcionamiento de los puertos y de los servicios de transporte marítimo de las regiones en desarrollo

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Bibliografía sobre transporte en Chile

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Biocombustibles líquidos para transporte en América Latina y el Caribe

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Los cambios en los sistemas integrados de transporte masivo en las principales ciudades de América Latina

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Políticas de movilidad urbana e infraestructura urbana de transporte

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El potencial de servicios multimodales en el corredor de transporte Asunción - Montevideo

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Ecoeficiencia y desarrollo de infraestructura urbana sostenible en Asia y América Latina: estrategias y medidas para el desarrollo de infraestructura de transporte urbano basada en principios de ecoeficiencia. Análisis aplicado al Área Metropolitana de La Serena y Coquimbo

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Metodología de evaluación de políticas públicas de vivienda y transporte urbano bajos en carbono. Innovación ambiental de servicios urbanos y de infraestructura: hacia una economía baja en carbono

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Institucionalidad y transporte público urbano: Santiago de Chile y Medellín, Colombia. Innovación ambiental de servicios urbanos y de infraestructura: Hacia una economía baja en carbono

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