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Virtuoso L.S.,Federal University of Alfenas | Vello K.A.S.F.,Centro Universitario Of Caratinga Unec | De Oliveira A.A.,Federal University of Alfenas | Junqueira C.M.,Federal University of Alfenas | And 5 more authors.
Journal of Chemical and Engineering Data | Year: 2012

Phase diagrams have been determined for aqueous two-phase systems containing (EO) 11(PO) 16(EO) 11, notation L35 (50% EO), and sodium citrate, sodium tartrate, or sodium hydrogen sulfite at different temperatures. The influences of the temperature and anion on the behavior of these systems were also analyzed. The temperature effect on the position of the binodal curves for systems containing sodium citrate and tartrate was not relevant, indicating a small enthalpy contribution associated with the phase separation. However, an enthalpic contribution for the phase splitting of the systems formed by sodium hydrogen sulfite was observed. The ability of these three salts to induce the formation of a biphasic system with L35 followed the order sodium citrate > sodium tartrate > sodium hydrogen sulfite. In this work, the nonrandom two-liquid (NRTL) model was used to obtain new interaction energy parameters. The results were analyzed using root-mean-square deviations between experimental and calculated data in equilibrium phases and were considered satisfactory. © 2012 American Chemical Society.


Costa H.C.,Federal University of Viçosa | da Silva E.T.,Federal University of Viçosa | Campos P.S.,Centro Universitario Of Caratinga Unec | Oliveira M.P.C.,Federal University of Viçosa | And 2 more authors.
Herpetology Notes | Year: 2010

Herein, we report necrophilia (Davian behaviour) in the lizard Ameiva ameiva in Brazilian Atlantic Forest Domain. A male A. ameiva was found during a sunny day courting and trying to copulate with a road-killed female. The presence of developed ovarian follicles confirmed that the female was in breeding condition. The female probably died while making a chemical trail to attract reproductive males. Apparently the male's behaviour was influenced by the high temperature of the female's body that was warmed up by the heat of the sun. Although Davian behaviour is not expected to occur frequently, a high number of dead reproductive females in Brazilian roads could result in a high frequency of necrophilia in A. ameiva.


Virtuoso L.S.,Federal University of Alfenas | De S. Silva L.M.,Centro Universitario Of Caratinga Unec | Malaquias B.S.,Centro Universitario Of Caratinga Unec | Vello K.A.S.F.,Centro Universitario Of Caratinga Unec | And 5 more authors.
Journal of Chemical and Engineering Data | Year: 2010

Liquid-liquid equilibrium data for aqueous two-phase systems formed by a mixture of triblock copolymer L35 (M n = 1900 g·mol -1), sodium hydroxide or potassium hydroxide, and water were measured as a function of four temperatures, (283.15, 293.15, 303.15, and 313.15) K. The influences of the temperature and cation on the behavior of these systems were analyzed. Temperature variation affected more intensively the tie-line slope than the binodal position. The exchange of sodium cation for the potassium also leads to an increase of the two-phase region of the diagrams in each studied temperature. The reliability of all the tie-line experimental data was ascertained by applying the Othmer-Tobias correlation. The interaction parameters of the NRTL model and UNIFAC model group-interaction parameter were estimated for the liquid-liquid equilibrium at temperatures between (283.15 and 313.15) K, with a total of 80 tie-lines for each model. The results of the predicted liquid-liquid equilibrium data by NRTL and UNIFAC models showed that the NRTL was more able to represent the studied aqueous two-phase systems. © 2010 American Chemical Society.


de Lima e Silva C.,Federal University of Ouro Preto | da Costa A.T.,Federal University of Ouro Preto | Landa G.G.,Centro Universitario Of Caratinga Unec | Camargos Fonseca H.F.,Federal University of Ouro Preto | Silveira A.,Federal University of Ouro Preto
Acta Limnologica Brasiliensia | Year: 2013

Aim: The aim was to verify the geochemical composition of sediments samples (riverbed and bank) and the relationship of the following elements: Al, As, Cd. Cr, Cu, Fe, Mn, Ni and Zn with the zooplankton community. Methods: Bank and riverbed sediments were collected in four sampling points along the studied area, in June/2010 (dry season) and March/2011 (rainy season). Tree types of analysis were performed: granulometric, mineralogical (by X-Ray diffractometer) and geochemical (by ICPOES), where for the last two types, only a fraction of silt/clay (<0.062 mm) was used, and the results were compared with the following reference values: Local Reference Value (Costa et al., 2010), Quality Reference Values (São Paulo, 2005), PEC and TEC values (MacDonald et al., 2000). For identification of the zooplankton community, riverbed and bank samples were collected in polyethylene bottles, suspended with deionized water (bank sample only), stained with Rose Bengal and preserved in formalin at 4%. Results: As concentrations at Col sampled point were 18 times greater than the Local Reference Value (3.84 mg.kg-1). Cd concentrations were greater than the values established by the QRV (<0.5 mg.kg-1) and PEC (4.98 mg.kg-1) in almost all the sampled points, regarding seasonality. The following zooplanktonic species were identified: Arcella costata (Ehrenberg, 1847), Arcella discoides (Ehrenberg, 1843), Arcella vulgaris (Ehrenberg, 1830), Centropyxis aculeata (Ehrenberg, 1838), Centropyxis ecornis (Ehrenberg, 1841), Difflugia sp., Difflugia acuminata (Ehrenberg, 1838), Euglypha laevis (Perty, 1849), Trynema enchelys (Ehrenberg, 1938), Asplanchna priodonta (Gosse, 1850), and Bedelloida, with, approximately 81% belonging to the Protozoa group. Conclusions: The studied area, with the exception of the Tripuí point, was found to be impacted by historical gold exploration in the region, as well as by the growing urbanization. Within the elements considered to be the most toxic to the biota, As and Cd violated all their reference values. In spite of high concentrations of major and trace elements encountered at downstream points, testacea species were identified, suggesting that this group has the capacity to adapt to adverse situations.

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