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Caxias do Sul, Brazil

The University of Caxias do Sul is among the largest universities in the Brazilian state of Rio Grande do Sul, by number of students . It was founded in 1967. It is almost completely located in Caxias do Sul, but there are also campi in Bento Gonçalves, Vacaria, Farroupilha, Guaporé, Nova Prata, São Sebastião do Caí, Canela and Veranópolis. Wikipedia.

Campos R.A.,University of Caxias do Sul
Genetics and molecular research : GMR | Year: 2010

Pathogenicity of strains of the entomopathogenic fungus Beauveria bassiana and endophytic strains of Beauveria sp against the bovine tick Rhipicephalus (Boophilus) microplus was tested in laboratory bioassays and under field conditions. Suspensions containing 10(5), 10(7) and 10(9) conidia/mL were prepared of each fungal strain for laboratory bioassays. The ticks were maintained at 28 degrees C, 90 +/- 5% relative humidity, and the following variables were evaluated: initial female weight, egg weight, hatching percentage, reproductive efficiency, and percentage control. For tests under field conditions, a Beauveria suspension containing 10(6) conidia/mL was sprayed on tick-infested cows. After 72 h, the ticks were collected to estimate mortality under field conditions. Laboratory bioassays showed a mortality of 20 to 50% of the ticks seven days after inoculation with 10(7) Beauveria conidia/mL. Under field conditions 10(6) Beauveria conidia/mL induced 18-32% mortality. All Beauveria strains were effective in biological control of R. (Boophilus) microplus under laboratory and field test conditions. This is the first demonstration that endophytic fungi can be used for biological control of the cattle tick; this could help reduce environmental contamination by diminishing the need for chemical acaricides. Two endophytic strains were isolated from maize leaves and characterized by molecular sequencing of 5.8S rDNA ITS1 and ITS2 and morphological analyses of conidia. We found that these two endophytic Beauveria isolates, designated B95 and B157, are close to Beauveria amorpha.

Dani C.,University of Caxias do Sul
Genetics and molecular research : GMR | Year: 2012

Grape juices are an important source of food antioxidants. Unfortunately, there is little data about the mineral composition and the antioxidant, mutagenic and antimutagenic activities of grape juice in eukaryote cells. We evaluated the mineral contents (Mg, Ca, Mn, Fe, Cu, Zn, Si, S, Cl) of grape juices, the antioxidant, mutagenic and/or antimutagenic activities of the juices in the yeast Saccharomyces cerevisiae, and looked for a possible association between mineral content and antioxidant, mutagenic and/or antimutagenic activities of juice samples. Eight commercial grape juices, four purple (Bordo variety) and four white (Niagara variety), were evaluated. Most of the minerals were in similar concentrations in purple and white grape juices, except for calcium and copper; purple grapes had more calcium content and white grapes had more copper content. All grape juices had important antioxidant and antimutagenic activities in S. cerevisiae and prevented the oxidative damage provoked by hydrogen peroxide (P < 0.05). Positive correlations (P < 0.05) were observed between antioxidant and antimutagenic activities and mineral content. In this context, we concluded that the grape juices, white and purple, are an important mineral source, and these contents explain, in part, the important antioxidant and antimutagenic activities.

Camargo K.C.,Federal University of Rio Grande do Sul | Michels A.F.,University of Caxias do Sul | Rodembusch F.S.,Federal University of Rio Grande do Sul | Horowitz F.,Federal University of Rio Grande do Sul
Chemical Communications | Year: 2012

Superhydrophobic self-cleaning surfaces were produced with simultaneous wide-angle optical transmittance in the near-infrared region and antireflection properties from combination of multi-scale surface topology based on silica nanoparticles, index grading and interference. © The Royal Society of Chemistry 2012.

Zambra D.A.B.,University of Caxias do Sul | Rech C.,Federal University of Santa Maria | Pinheiro J.R.,Federal University of Santa Maria
IEEE Transactions on Industrial Electronics | Year: 2010

This paper presents a comparison of three topologies of multilevel inverters applied to drive an induction motor of 500 kVA/4.16 kV rating. The multilevel inverters analyzed are the following: a neutral-point-clamped inverter, a symmetrical cascaded multilevel inverter, and a hybrid asymmetrical cascaded multilevel inverter. The performance indexes used in the comparison are total harmonic distortion, first-order distortion factor, second-order distortion factor, common-mode voltage, semiconductor power loss distribution, and heat-sink volume. The multilevel inverters are designed to present 99% efficiency at the nominal operating point, and the aforementioned performance indexes are compared for distinct values of amplitude modulation depth. © 2010 IEEE.

Wander P.R.,University of Caxias do Sul | Altafini C.R.,University of Caxias do Sul
Energy | Year: 2011

There are many studies showing that the performance results for engines operating with biofuels are acceptable, although very few long-term analysis of wear and maintenance problems are shown. Three mono-cylinder compression ignition engines were tested for approximately 1000. h each, with pure diesel oil (D100), pure soy methyl ester (SME100) and pure castor oil methyl ester (CME100). The lubricating oil analysis didn't reveal any excessive amount of metals compared to the engine with pure diesel. Viscosity decreased very soon to values below the minimum recommended due to dilution with the methyl esters, especially with SME100. The injection system analysis showed that opening pressures, hydraulic flux and corrosion levels were acceptable. The SME piston showed a very small crack. A higher amount of carbon deposits and gum formation was found over biofuel pistons, indicating poor combustion. Piston ring seating and gap were inside specification. Cylinder liners presented no damage on running surface. The valves presented abrasive and adhesive wear, contact fatigue for SME100 and marks at valve seating for CME100, considered acceptable after 1000. h of test. The results obtained show that the use of pure methyl esters fuels was acceptable for these engines regarding wear and maintenance problems. © 2010 Elsevier Ltd.

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