RESUMO
In the framework of understanding the transport mechanism that governs the filtration of NO3- solution through a γ-Al2O3 membrane with a nominal pore size of 5 nm at low ultrafiltration, a series of various types of nitrate solutions and operating conditions were investigated. The effect of filtration parameters such as pH, applied pressure and NO3- concentration on the selectivity and permeability of the membrane were studied using binary solutions (KNO3, NaNO3, Ca(NO3)2 and Mg(NO3)2) and ternary solutions ((NaNO3 + KNO3), (NaNO3 + Ca(NO3)2) and (Mg(NO3)2 + Ca(NO3)2). The experimental filtration results showed that high NO3- rejection was observed when pH was close to the point of zero charge of the membrane for both binary and ternary solutions. NO3- rejection increased with an increase of applied pressure. The rejection gradually decreased when the initial NO3- concentration increased. It appeared that the valency and hydrated radius of associated cation had a dramatic effect on NO3- rejection, with the divalent cations being more rejected than monovalent cations. In order to get to natural water complexity, three different samples of mineral water doped with NO3- from two different sources were studied at optimized operating conditions (25 ppm of NO3- and 6 bar). Experimental results demonstrated that NO3- rejection strongly depended upon the total mineralization and the presence of divalent anions in solution. In addition, the obtained results showed the potential use of γ-Al2O3 ultrafiltration membrane for denitrificatoin of contaminated water especially in Moroccan agricultural areas.
RESUMO
Candida dubliniensis was first identified in Dublin in 1995 in oral isolates recovered from human immunodeficiency virus (HIV)-infected individuals. Although C. dubliniensis has been primarily recovered from the oral cavities of HIV-infected individuals, the number of reports describing its isolation from HIV-negative individuals, including cases of candidaemia, is growing. To date there has only been one report of C. dubliniensis candidaemia in an HIV-infected patient, in this case from the USA. In the present study, 2 Candida isolates recovered from blood samples were presumptively identified as C. dubliniensis on the basis of their dark green coloration on CHROMagar Candida medium and lack of growth at 45 degrees C. This identification was confirmed by carbohydrate assimilation profile analysis and by polymerase chain reaction (PCR) analysis with C. dubliniensis-specific PCR primers. Both isolates were susceptible to fluconazole. The isolates were found retrospectively to be from a single HIV-infected patient who was receiving broad-spectrum antibacterials at the time of isolation of C. dubliniensis from blood. This study represents the first documented case of C. dubliniensis bloodstream infection in Ireland and is only the second case of C. dubliniensis bloodstream infection identified in an HIV-infected individual anywhere in the world.
