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.

Intermittency and the Exchange of Scalars in the Nocturnal Surface Layer

Abstract: The determination of nocturnal surface fluxes in low wind conditions is a major problem for micrometeorological studies. The eddy correlation technique, extensively used in field measurements, becomes inappropriate if not enough turbulent activity exists. At the same time, the phenomenon of turbulence intermittency is responsible for the existence of localized events of short duration within which a large fraction of the total nighttime scalar exchange occurs. The scalar flux within a certain intermittent event varies considerably depending on the window used for the flux calculation. In many cases, events with very different time durations occur in the same night, and therefore, the proper determination of the surface flux would require averaging within data windows of different sizes for each event. In this work, the surface exchanges of temperature, moisture and carbon dioxide are analysed at a micrometeorological tower at southern Brazil. Intermittent turbulence is a common occurrence at the location. The analysis shows that the fluxes vary with turbulence intensity and the estimation technique. A variable-window size method for flux estimation is suggested and shown to cause an increase in the magnitude of the nocturnal surface fluxes

Improvement of the viability of encapsulated probiotics using whey proteins

Abstract: The viability of Lactobacillus acidophilus encapsulated in calcium alginate particles coated with up to three levels of multilayer was analysed. Probiotic survival under simulated gastrointestinal conditions, thermal treatment and storage conditions were also investigated, as well as the morphology and mean particle size. The encapsulation efficiency obtained was higher than 80% in all multilayer treatments, while the diameter ranged from 107 μm to 222 μm among the different numbers of particle layers. Microencapsulated L. acidophilus presented viability during the simulated gastrointestinal conditions, and the treatment with a layer of whey protein (A1) provided greater protection for the probiotics in all the stages of the analysis, with final count of 9.19 CFU g−1. In the thermal resistance tests, the multilayer particles promoted greater protection for probiotic cultures in relation to the free cells that did not resist the tested conditions. The storage for up to 120 days at refrigeration and freezing temperatures were more efficient for all types of multilayer microparticles when compared to free cells. The results suggest that multilayer microparticles present an effective method to improve the probiotic viability during storage, thermal treatments and gastrointestinal conditions.

Nitrogênio e potássio em milho irrigado: análise técnica e econômica da fertilização

Abstract: Irrigation increases the probability to obtain high crop grain yield, but demands a technical and economical reasonable use of agricultural inputs, especially nitrogen fertilizers. The objective was to determine the more adequate rates of nitrogen and potassium for corn (Zea mays L.) grain yield and the better economical return of the fertilization in corn under sprinkle irrigation. The experiment was carried out in the years 2002/03 and 2003/04 in Cruz Alta-RS, Brazil, in a crop farm using central pivot irrigation system. The soil used was an Oxisol (Hapludox). The corn effective population totalized 78.000 and 71.000 plants ha-1 for the years 2002/03 and 2003/04, respectively, using the hybrid Pioneer 30F44. The treatments were composed by 0, 80, 120, 160, 200 and 240kg ha-1 of N (urea) combined with 0, 40, 80 and 120kg ha-1 of K2O (potassium chloride). The experiment was set in a randomized block design with four replicates. The maximum corn grain yield under sprinkle irrigation was obtained with N rates between 283 and 289kg ha-1, but the maximum economic efficiency was between 156 and 158kg of N ha-1, without any increment in grain yield with potassium application. These results show that, in many situations, farmers are using rates of nitrogen and potassium fertilizers over than necessary.

Acute Brain Damage Induced by Acetaminophen in Mice: Effect of Diphenyl Diselenide on Oxidative Stress and Mitochondrial Dysfunction

Abstract: Organoselenium compounds exhibit antioxidant activity, as well as a variety of biological activities, with potential pharmacological and therapeutic applications. The aim of this study was to investigate the effect of diphenyl diselenide (PhSe)2 in reversing oxidative brain damage and mitochondrial dysfunction caused by administration of acetaminophen (APAP) in mice. Mice received a toxic dose of APAP, followed by a dose of (PhSe)2 1 h later. Four hours after the administration of APAP, plasma was withdrawn from the mice and used for biochemical assays of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as markers of hepatotoxicity. Brain homogenate was examined to determine oxidative stress. Isolated brain mitochondria were examined to quantify mitochondrial transmembrane's electrical potential and mitochondrial swelling and to estimate reactive oxygen species (ROS) production. APAP administration caused an increase in plasma ALT and AST activities. APAP administration also caused a significant increase in the levels of thiobarbituric acid reactive substances (TBARS) and dichlorofluorescein oxidation in brain homogenate. Similarly, mitochondrial swelling and ROS production increased after APAP administration. APAP treatment also caused a decrease in Na+ , K+ - ATPase activity and in mitochondrial membrane potential. These alterations observed in the brain of APAP-treated mice were restored by (PhSe)2. Glutathione levels were decreased by APAP, but (PhSe)2 did not reverse this change. Treatment with (PhSe)2 after APAP administration can reverse the neurotoxicity caused by a single toxic dose of APAP. The neuroprotective effect of (PhSe)2 is likely associated with its antioxidant properties.

Desempenho de sementes de soja sob condições diferentes de potencial osmótico

Abstract: The mineral residues were accumulated in the soil due to successive fertilization as a consequence of annual cropping of the laud, wich change the hydric potential and affect the physiological performance of the seeds. The evaluation of the germination and vigor of the soybean seeds were performed in different conditions of the osmotic potential, seeds of lots A and B from FEPAGRO RS 10 cultivar were placed on a towel paper moistened with PEG 6000, NaCl, KCl and MgCl2 to obtain the osmotic potentials: zero; -0.05; -0.10; -0.20; -0.40 and -0.80 MPa. The results were evaluate by a standard germination test (a first and a final count), seedling length and dry weight. The statistical analysis indicated that the decrease in water potential induced by the treatments reduced seed quality and seed vigor was more affected than seed germination. The effect of reduced water potential on seeds and seedlings also depends on the initial quality of the seeds, the salt used and its concentration. PEG 6000 produced more stressing effects on soybean seed quality than the salts when the osmotic potential was up to -0.80 MPa. The potential osmotic of -0.80 MPa inducet by MgCl2 and PEG 6000 hinders germination and decreases seed vigor of soybean seeds.