Federal Institute Goiano IF Goiano

Rio Verde de Mato Grosso, Brazil

Federal Institute Goiano IF Goiano

Rio Verde de Mato Grosso, Brazil
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Faria D.M.,Federal Institute Goiano IF Goiano | Dourado S.M.,Federal Institute Goiano IF Goiano | Do Nascimento J.P.L.,Federal Institute Goiano IF Goiano | Nunes E.D.S.,Federal Institute Goiano IF Goiano | And 5 more authors.
Materials Research | Year: 2017

The development of controlled delivery system formulations has received increasing interest in the agriculture area. Tebuthiuron (TBH) is the most commonly used herbicide for weed control in sugar cane and cotton crops. The TBH and some of its metabolites are detected in surface water by leaching process, evidencing contamination and the need for an efficient process to decrease pesticide residues. The development of a controlled system release appears as a good solution. The present investigation aimed to study the development and evaluation of alginate microparticles as a delivery system for the TBH. The calcium alginate microparticles were prepared from the crosslinking of sodium alginate by Ca++ containing varied amounts of TBH supplied in CaCl2 aqueous solution. The particle size and morphological analysis of microparticles were determined by optical microscopy (OM) and by field emission gun scanning electron microscopy (FEG-SEM). The encapsulation efficiency and release of TBH studies was accessed by UV-vis spectroscopy. The results show that the polymeric microparticles containing TBH can be obtained successfully through a simple method and is suitable as a controlled release carrier system for herbicides and can be effective for controlling weeds. © 2017, Universidade Federal de Sao Carlos. All rights reserved.

Dourado Junior S.M.,Federal Institute Goiano IF Goiano | Nunes E.S.,Federal Institute Goiano IF Goiano | Marques R.P.,Federal Institute Goiano IF Goiano | Rossino L.S.,Sorocaba Technological College FATEC | And 4 more authors.
Journal of Materials Science | Year: 2017

The use of herbicides is important to eliminate losses of weed interference on crops. However, excessive and inappropriate employment of these substances can cause serious consequences to the environment. In this way, the release system is very attractive for the weed control in the agriculture area. The aim of this work was to study a new delivery system for sulfentrazone herbicide encapsulated into the calcium alginate (Ca-ALG) microparticles for the weed control. The alginate microparticles were prepared via ionotropic gelation method and characterized by using optical microscopy, scanning electron microscopy, and thermogravimetric and differential thermal analysis. The controlled release (Mt/M∞ vs. time) of the sulfentrazone herbicide was also analyzed using UV–Vis spectroscopy where we proposed different mathematical models to understand the mechanisms of controlled release of the herbicide. Furthermore, the release tests in field trial weed control were conducted using bioindicator species (Cucumis Sativus—Cucumber) to study the phytotoxicity evaluation caused by the Ca-ALG microparticles at different concentrations and their relationship with leaching depth. The results showed that the Ca-ALG microparticles exhibited good encapsulation efficiency (%EE): 76.11, 78.62, and 80.42% for the 4, 5 and 6 g L−1 concentration of herbicide. The release rates in the region I were 39.2, 46.5, and 35.5 mg s−1 for the 4, 5, and 6 g L−1 of herbicide concentration, respectively. The Ca-ALG microparticles containing sulfentrazone herbicide demonstrated potential application in controlled release platforms in agricultural as well as for controlling of weeds and minimization of leaching processes. © 2017 Springer Science+Business Media New York

Lopes H.S.M.,Sorocaba Technological College | Moreto J.A.,Federal Institute Goiano IF Goiano | Manfrinato M.D.,Sorocaba Technological College | Da Cruz N.C.,São Paulo State University | And 3 more authors.
Materials Research | Year: 2016

P20 steel, which is mainly used in plastic molds, was thermochemically treated by ion plasma nitriding and solid and gas carburization. In this work, the solid and gas carburization were performed at 925 °C for four different durations. The ion plasma nitriding was performed at 520 °C for four different durations. The thermochemical treatment increased the micro abrasive wear resistance of the studied material. The gas carburizing treatment resulted in a greater surface microhardness. Longer treatment times increased the effectiveness of the thickness layer in all cases. The solid carburization produced a larger thickness layer than the gas carburization and ion nitriding.

De Almeida Rosa A.G.,Sorocaba Technological College FATEC | De Almeida Rosa A.G.,Federal University of São Carlos | Moreto J.A.,Federal Institute Goiano if Goiano | Manfrinato M.D.,Sorocaba Technological College FATEC | And 2 more authors.
Materials Research | Year: 2014

The friction and wear properties of AISI 1045 steel, nylon 6.6 composites with different types and percentages of reinforcement and a nitrile rubber, Alpha 66, were submitted to sliding wear tests. The five types of nylon 6.6 composites tested generated matching, low values for the coefficient of friction. This may be due to the greater influence of the nylon 6.6 matrix on the coefficient of friction. However, the wear in nylon composites showed wide variation, determined by the type of reinforcement added to the composite. The other two materials tested, nitrile rubber and 1045 steel, showed behavior different from that of the composites. The NBR (signifying a norm established by the Brazilian Association of Technical Norms) rubber showed a superior coefficient of friction and greater wear. On the other hand, the steel showed a high coefficient of friction and low wear, suggesting that the coefficient of friction has no direct connection to the wear resistance of the materials studied here.

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