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Ventura S.P.M.,University of Aveiro | de Barros R.L.F.,Tiradentes University | Sintra T.,University of Aveiro | Soares C.M.F.,Tiradentes University | And 4 more authors.
Ecotoxicology and Environmental Safety | Year: 2012

A wide range of ionic liquids (ILs), containing a diverse set of cations, anions and alkyl chain lengths, was screened for their antimicrobial activity toward four microorganisms, Escherichia coli CCT-0355, Staphylococcus aureus ATCC-6533, Fusarium sp. LM03 and Candida albicans ATCC-76645. For that purpose an adaptation of the Agar Diffusion test was validated and successfully applied as a rapid screen method to identify toxic ILs, avoiding the use of more complex and expensive techniques. The effects of the cation alkyl chain length were studied, being observed both the "alkyl side chain" effect (increase in antimicrobial activity with the elongation of the alkyl chain) and "cut-off" effect (beyond a given chain length, the toxicity cannot be increased any further). Imidazolium-based ILs have in general, negative effects on the growth of these microorganisms dependent on the anion and alkyl chain length (growth inhibition halo from 1.98±0.04mm for [C2mim]Cl to 39.53±0.81mm for [C10mim]Cl). On the opposite, the phosphonium-based ILs do not seem to have negative effects for the longest alkyl chains (growth inhibition halos between 0.00±0.00 and 7.30±0.42mm). It was also observed that the alkyl chain, cation family, and anion moiety all have significant effects on the antimicrobial activity these effects being well correlated with the lipophilicity of the ILs tested. The results also show that the microorganisms responses to the diverse ILs tested are dependent on their morphologic differences. © 2012 Elsevier Inc. Source

Goes M.A.O.,Nucleo de Vigilancia Epidemiologica de Agravos transmissiveis | de Melo C.M.,Institute Tecnologia e Pesquisa | Jeraldo V.L.S.,Institute Tecnologia e Pesquisa
Revista Brasileira de Epidemiologia | Year: 2012

Introduction: Considered as a neglected disease by the WHO, visceral leishmaniasis (VL) has expanded and urbanized. Its transmission and expansion have been linked to several factors. Objective: To evaluate the epidemiological aspects of VL in the city of Aracaju/SE, through retrospective studies of the historical series of human and canine VL in the 1999-2008 period. Methods: Secondary data from SINAN (Information System for Reportable Diseases) for human cases were used. Data from canine surveys and from the Zoonosis Control Center ́s (ZCC) passive demand were used for canine cases. Results: 192 autochthonous cases of human VL were reported, and 63.5% were male. Children aged 1-4 years were the most affected (29.2%), followed by adults aged 20-29 years (15.6%) and children aged 5-9 years (15.1%). General mortality was 8.9%, and it was higher for the 60-69 year age group (60%); 32.3% of autochthonous cases performed serology for HIV, with a 6.9% positivity. Laboratory results were con-frmed mostly by indirect isolated immu-nofuorescence (71.1%). 58,161 dogs were serologically tested for VL, with a positivity rate of 5.4%, while 87.0% of the surveys conducted annually by the ZCC, have a 4.4%positivity rate for VL. Of the 7,501 dogs that were brought to the ZCC for multiple complaints, the serological test was positive in 12.0%. Conclusion: Data show the ende-micity of VL in the city, revealing the need for actions to reduce the risk of the population, mostly for the group with higher incidence and mortality, such as improvement in the diagnosis of VL and its HIV-associated infection, along with monitoring of the dog population, among others. Source

De Souza R.L.,Tiradentes University | Barbosa J.M.P.,Tiradentes University | Zanin G.M.,State University of Maringa | Lobao M.W.N.,Tiradentes University | And 3 more authors.
Applied Biochemistry and Biotechnology | Year: 2010

The hydrolysis of triglycerides at the oil-water interface, synthesis of esters and transesterification in microaqueous conditions are catalysed by lipase. For its application, a proper purification method was necessary. This study examined the application of an aqueous two-phase system to partition porcine pancreatic lipase. The influence of molecular weight and concentration of polyethylene glycol (PEG), tie line length (TLL), potassium phosphate concentration, sodium chloride (NaCl) addition and temperature in the partition was studied. The enzyme was more efficiently purified in PEG 8,000 at 14.5 °C (PF∈=∈3.89-fold), presenting more recoveries at the top phase with shorter TLL and lower concentrations of PEG and potassium phosphate. Moreover, the increase of these variables repressed the purification and the further addition of NaCl did not promote the purification of the enzyme. These results demonstrated the efficiency of the aqueous two-phase system on lipase purification. © 2010 Springer Science+Business Media, LLC. Source

de Souza R.L.,Tiradentes University | Campos V.C.,Tiradentes University | Ventura S.P.M.,University of Aveiro | Soares C.M.F.,Tiradentes University | And 4 more authors.
Fluid Phase Equilibria | Year: 2014

Aqueous biphasic systems (ABS) are relevant for the development of environmentally friendly and "biocompatible" separation processes. However, the common polyethylene glycol (PEG) polymers present a limited range of applicability, due to the low polarity of the PEG-rich phase. To overcome this limitation, a new approach was recently proposed based on the use of ionic liquids (ILs) as adjuvants in ABS, enlarging the polarity range of these systems. This work addresses the use of imidazolium-based ILs as ionic adjuvant compounds in the formation of ABS, namely potassium salts. +. water. +. PEG (1500, 4000, 6000 and 8000). To explore the differences induced by the presence of the IL as adjuvant the partition behavior of two dyes, Chloranilic Acid and Rhodamine 6G, is analyzed and correlated with the phase behavior and the IL distribution on the ABS under study. © 2014 Elsevier B.V. Source

Cardoso G.D.B.,Tiradentes University | Souza I.N.,Tiradentes University | Pereira M.M.,University of Aveiro | Freire M.G.,University of Aveiro | And 4 more authors.
Separation and Purification Technology | Year: 2014

In this work, it is shown that novel aqueous two-phase systems can be formed by the combination of acetonitrile and polysaccharides, namely dextran. Several ternary phase diagrams were determined at 25 °C for the systems composed of water + acetonitrile + dextran. The effect of the dextran molecular weight (6000, 40,000 and 100,000 g mol-1) was ascertained toward their ability to undergo liquid-liquid demixing. An increase in the dextran molecular weight favors the phase separation. Furthermore, the effect of temperature (25, 35 and 45 °C) was evaluated for the system constituted by the dextran of higher molecular weight. Lower temperatures are favorable for phase separation since lower amounts of dextran and acetonitrile are required for the creation of aqueous two-phase systems. In general, acetonitrile is enriched in the top phase while dextran is majorly concentrated in the bottom phase. The applicability of this new type of two-phase systems as liquid-liquid extraction approaches was also evaluated by the study of the partition behavior of a well-known antioxidant - vanillin - and used here as a model biomolecule. The optimized conditions led to an extraction efficiency of vanillin of 95% at the acetonitrile-rich phase. Source

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