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.

Functionalization of carbon nanotubes through the chemical binding of atoms and molecules

Abstract: We present a proposal for altering the electronic properties of single wall carbon nanotubes (SWNT's) through the chemical binding of atoms and molecules. This binding would be performed at Si substitutional defect sites, which would guarantee a high stability to the system. We argue that, by appropriately choosing the atom or radical bound to the Si atom, one can have a greater doping flexibility than has been achieved so far, and can, in principle, engineer transport, optical, or other properties of SWNT's. These conclusions are based on detailed first-principles calculations for a $\mathrm{Si}\ensuremath{-}X$ doped semiconducting (10,0) SWNT, for $X={\mathrm{F},$ Cl, H, ${\mathrm{CH}}_{3},$ and ${\mathrm{SiH}}_{3}}.$

Diphenyl Diselenide Protects Against Mortality, Locomotor Deficits and Oxidative Stress in Drosophila melanogaster Model of Manganese-Induced Neurotoxicity.

Abstract: Several experimental and epidemiological reports have associated manganese exposure with induction of oxidative stress and locomotor dysfunctions. Diphenyl diselenide (DPDS) is widely reported to exhibit antioxidant, anti-inflammatory and neuroprotective effects in in vitro and in vivo studies via multiple biochemical mechanisms. The present study investigated the protective effect of DPDS on manganese-induced toxicity in Drosophila melanogaster. The flies were exposed, in a dietary regimen, to manganese alone (30 mmol per kg) or in combination with DPDS (10 and 20 µmol per kg) for 7 consecutive days. Exposure to manganese significantly (p < 0.05) increased flies mortality, whereas the survivors exhibited significant locomotor deficits with increased acetylcholinesterase (AChE) activity. However, dietary supplementation with DPDS caused a significant decrease in mortality, improvement in locomotor activity and restoration of AChE activity in manganese-exposed flies. Additionally, the significant decreases in the total thiol level, activities of catalase and glutathione-S-transferase were accompanied with significant increases in the generation of reactive oxygen and nitrogen species and thiobarbituric acid reactive substances in flies exposed to manganese alone. Dietary supplementation with DPDS significantly augmented the antioxidant status and prevented manganese-induced oxidative stress in the treated flies. Collectively, the present data highlight that DPDS may be a promising chemopreventive drug candidate against neurotoxicity resulting from acute manganese exposure.

Correlações genéticas entre medidas de perímetro escrotal e características produtivas e reprodutivas de fêmeas da raça Nelore

Abstract: Genetic parameters for scrotal circumference at 12 (SC12) and at 18 months of age (SC18) of males, and yearling weight (W365), weight at first calving (WFC), age at first calving (AFC), days to first calving (DC) and length of first gestation (GL) of females were estimated using records from 9,932 females and 14,521 males from 28 Nellore herds, located in the South and Southeast regions of Brazil. Covariance components were estimated by REML, fitting bivariate animal models. Heritability estimates were high for SC12 (0.25 to 0.26), SC18 (0.35 to 0.37), W365 (0.35 and 0.38), WFC (0.40 and 0.41) and GL (0.19 and 0.20), but low for AFC (0.14 and 0.15) and DC (0.05 and 0.06). Genetic correlation estimates between SC12 and W365, WFC, AFC, DC and GL were 0.28, 0.30, -0.15, -0.04 and 0.10, respectively. In the same order, the respective genetic correlation estimates between SC18 and female traits were 0.29, 0.32, -0.21, -0.08 and 0.14. These results suggest that selection to improve female fertility efficiency based on SC18 would be more effective than by using SC12.

Critical limits of soil penetration resistance in a rhodic Eutrudox

Abstract: Soil penetration resistance is an important indicator of soil physical quality and the critical limit of 2 MPa has been widely used to characterize the soil physical quality, in both no-tillage and conventional systems. The aim of this study was to quantify the influence of different tillage and cropping systems on the soil penetration resistance in a Rhodic Eutrudox. The experiment was carried out in a 5 × 2 factorial, completely randomized block design (tillage systems vs cropping systems), with four replications. The tillage systems consisted of: conventional tillage disk harrow; minimum tillage with annual chiseling; minimum tillage with chiseling every three years; no-tillage for 11 consecutive years; and no-tillage for 24 consecutive years. The factor cropping systems was represented by: crop rotation and crop succession. The soil penetration resistance (SPR) was determined in 20 soil samples per treatment and layer (0.0-0.10; 0.10-0.20 and 0.20-0.30 m) for each soil matric potential: -6, -10, -33, -100, -500 kPa. The SPR was determined at a volumetric soil water content equivalent to the fraction of plant-available water of 0.7. There were no differences of soil penetration resistance between the two cropping systems. Differences in soil penetration resistance among tillage systems were related to the matric potential at which the samples were equilibrated. The critical SPR limit of 2 MPa normally used for conventional tillage should be maintained. However, this value of 2 MPa is inappropriate for the physical quality characterization of Rhodic Eutrudox under no-tillage and/or minimum tillage with chiseling. Regardless of the cropping systems, the critical SPR limit should be raised to 3 MPa for minimum tillage with chiseling and to 3.5 MPa for no-tillage.