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Departamento de Farmácia
36
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15
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Departamento de Ciências da Computação
1
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14
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Departamento de Agronomia
3
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14
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Publication History View all

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    ABSTRACT: Fire has been recognized as an important environmental process that affects soil systems. Here, we have reported the effects of temperature on soil aggregate properties of aggregate stability, mean weight diameter, water repellency, water retention, and soil carbon depletion due to soil heating. The study was performed under laboratory conditions by using a muffle furnace. However, realistic temperature gradients from 25 to 650 °C were obtained previously through measurements in the field. The soil tested here is a subtropical Humic Cambisol with 500 g kg− 1 clay content. Most of our results were different from those reported in the literature. Following the temperature gradient, we found a sharp threshold at ~ 550 °C. The threshold indicated two different mechanisms that affect soil aggregate properties. The first mechanism, which affects the physical characteristics of the aggregates, was associated with organic matter and water repellency reduction (≤ 550 °C). The second mechanism was due to the thermal fusion of particles and recrystallization of mineral clays at 650 °C. The reduction in soil organic carbon had a linear effect on aggregate stability, mean weight diameter, and water retention following a temperature gradient. We noted that the longer exposure time at moderate to high temperatures could not compensate for the effect of a very high peak temperature lasting for a short time on soil aggregates. For the tested soil, we found a mixed response pattern explaining the effect of soil heating on aggregate stability.
    Geoderma 10/2014; s 230–231:243–249. DOI:10.1016/j.geoderma.2014.04.025
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    ABSTRACT: Slurry sampling electrothermal atomic absorption spectrometry was used for direct determination of Cr, Pb and Cd in honey without sample pretreatment. The honey slurries were prepared in aqueous solution containing hydrogen peroxide and nitric acid. The slurries were directly introduced in the pyrolytic graphite tubes. Pd-Mg was used as a chemical modifier only for Cd determination. Analytical curves were performed with aqueous standards for Pb and Cr and with addition of fructose for Cd. The quantification limits for Cd, Pb and Cr were 2.0, 5.4 and 9.4ngg(-1), respectively. Acceptable precision of the methodology was obtained through repeatability and intermediate precision. In the accuracy study, recoveries were satisfactory (94-101%) for the three elements. The methodology was applied in honey from Paraná (Brazil). The concentrations of Pb, Cd and Cr ranged from 141 to 228ngg(-1), <2.0 to 8ngg(-1) and 83 to 94ngg(-1), respectively.
    Food Chemistry 03/2014; 146:166-73. DOI:10.1016/j.foodchem.2013.09.065
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    ABSTRACT: In this work, we investigated the morphological variation of the intromittent male copulatory organ (aedeagus) of specimens from natural populations of two cactophilic Drosophila species distributed in the southeast region of Brazil, Drosophila gouveai Tidon-Sklorz & Sene and Drosophila antonietae Tidon-Sklorz & Sene. It was explored how the within-species variability is arranged for both species, considering their historical and ecological features. Our results showed two distinct aedeagal morphologies for these species, and differences within species were observed only in D. gouveai as specimens could be distinguished by their population origin. In contrast, after size discrepancies correction, this feature was not detected in D. antonietae. The contrasting patterns of intraspecific variation, together with the other features exhibited by these two species, are most likely to be explained by differences in the historical host plant association and distribution and in demographic events, which determined the evolutionary history of these two South American cactophilic Drosophila species.
    Neotropical Entomology 08/2013; 42(4):384-92. DOI:10.1007/s13744-013-0128-2

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  • Address
    Rua Camargo Varela de Sá, 03 - Vila Carli, 85040-080, Guarapuava, Paraná, Brazil
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International Journal of Pharmaceutics 03/2005; 290(1-2):137-44. DOI:10.1016/j.ijpharm.2004.11.027
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