Measurements of activity coefficients at infinite dilution in vegetable oils and capric acid using the dilutor technique

This paper reports experimental activity coefficients at infinite dilution, gamma(not similar to)(i), for methanol, ethanol and n-hexane in three refined vegetable oils (soybean, sunflower, and rapeseed oils) measured using the dilutor technique (inert gas stripping method). The measurements were carried out in the temperature range between 313.15 and 353.15 K. Furthermore, activity coefficients at infinite dilution for various solutes (acetone, methanol, ethanol, n-hexane, cyclohexane and toluene) were measured in capric (decanoic) acid using the same technique in the temperature range from 313.13 to 353.30 K. The new data obtained for capric acid and soybean oil were compared with already published experimental data. Additionally, densities of the investigated vegetable oils were measured in the temperature range from 293.15 to 353.15K. Using the experimental gamma(not similar to)(i) values obtained over the temperature range, the partial molar excess Gibbs energy (Delta G(i)(E,not similar to)), enthalpy (Delta H-i(E,not similar to)) and entropy (Delta S-i(E,not similar to)) at infinite dilution were determined. The relative error for the gamma(not similar to)(i) measurements carried out using the dilutor technique is approximately +/- 2.5%. The measured gamma(not similar to)(i) data in the investigated refined vegetable oils were also compared with the results of the group contribution methods original UNIFAC and modified UNIFAC (Dortmund) and an extension of the latter method to triacylglycerols was proposed361215222CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP142122/2009-2; 290128/2010-2; 304495/2010-7; 483340/2012-0; 307718/2010-7; 301999/2010-408/56258-8 09/54137-1; 2010/16634-0Deutscher Akademischer Austausch Dienst (DAAD); INCT-EMA (Instituto Nacional de Ciencia e Tecnologia de Estudos do Meio Ambiente); Carl von-Ossietzky University Oldenbur

High frequency of colonization and absence of identifiable risk factors for methicillin-resistant Staphylococcus aureus (MRSA) in intensive care units in Brazil

Colonization of hospitalized patients with methicillin-resistant Staphylococcus aureus (MRSA) is of increasing concern. To evaluate this problem in Intensive Care Units (ICUs) in Brazil, we studied 100 patients admitted to two ICUs from April to June, 1997. Of the 100 patients, 70 were male, 53 were age 60 years or older, 55 were previously hospitalized, 78 were transferred to the ICU from other hospital units, 49 had received antibiotic therapy, and 66 had undergone recent surgery. Nasal and axillary swab cultures were obtained on admission and every 48 hours thereafter until discharge. MRSA were identified by plating any cultured S. aureus on Mueller-Hinton agar containing 6mug/ml of oxacillin. At the time of admission, 46 (46%) of the patients were colonized with MRSA. No associated risk factors for acquiring MRSA (age, previous hospitalization, prior surgery) could be identified. Of the 54 patients negative for MRSA on admission, 28 (52%) became colonized while in the ICU. Sixteen (22%) of the 74 colonized patients (colonized either on admission or during ICU stay) had associated respiratory or urinary tract infections due to MRSA, and 9 (56%) died. No correlation with special risk factors (invasive procedures, antibiotic use, age, chronic disease) was identified. MRSA occurred frequently, but there was minimal evidence of associated risk factors. Thus, control of MRSA cannot be accomplished by targeting special factors alone, but requires attention to preventing microbial spread in all areas. Of special concern is the high frequency of acquiring the organism in the ICU (52%). Education concerning the importance of hand washing, environmental surface cleaning, and barrier protection from infected patients is needed