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Rio Branco, Brazil

da Conceicao P.M.,Campus Universitario | Faroni L.R.A.,Federal University of Vicosa | Sousa A.H.,CCBN UFAC | Pimentel M.A.G.,Embrapa Milho e Sorgo | Freitas R.S.,Federal University of Vicosa
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2012

The aim of this study was to evaluate the insecticide activity of diatomaceous earth (DE), at different temperatures, on two populations of Tribolium castaneum and Rhyzopertha dominica previously diagnosed as resistant and susceptible to phosphine. The efficiency of DE in the control of the insects was evaluated at temperatures of 20, 25, 30, 35 and 40 ± 2 °C. The experiments were accomplished in Petri dishes containing 35 g of whole-wheat grain treated with DE in the dose of 1.0 kg t-1. The control was constituted by untreated wheat grain. Each Petri dish was infested with 30 adult insects. Insect mortality was registered seven days after the beginning of the bioassays. The experiment was conducted in a completely randomized design with three replications. The populations of T. castaneum and R. dominica, respectively, resistant and susceptible to phosphine have similar susceptibility patterns. The mortality of two populations of T. castaneum increased with increasing temperature. For R. dominica, the mortality did not change with the temperature.

Cortela G.,Institute Fisica | Lima K.M.,Federal University of Rio de Janeiro | Maggi L.E.,CCBN UFAC | Negreira C.,Institute Fisica | Pereira W.C.A.,Federal University of Rio de Janeiro
Pan American Health Care Exchanges, PAHCE | Year: 2015

A hydrogel-based (gellan gum) tissue mimicking material (TMM) was developed. Its acoustic and thermal properties were characterized. The hydrogel was combined with different sizes of glass spheres. The acoustic properties (attenuation coefficient and the speed of sound) were obtained as a function of the temperature range 20 to 45° C. Specific heat was determined experimentally by the standard mixture method for the same temperature range. The attenuation coefficient presented a quasi-linear dependence on the frequency, such as the most of mammalian tissues. The mean value was 0.59f 0,85 dB cm-1, at 30° C from 1 to 10MHz. The results suggest that the developed TMM has potential for several applications: development of standard dosimetry techniques, validation numerical models and determination the efficacy of hyperthermia devices. © 2015 IEEE.

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