40 research outputs found

    Outbreak by serratia marcescens producing carbapenemases in an adult intensive care unit

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    Serratia marcescens (SM) es un bacilo Gram-negativo perteneciente a la familia Enterobacteriaceae, reconocido como patógeno oportunista asociado a brotes nosocomiales. Es naturalmente resistente a tetraciclina, amoxicilina, amoxicilina-clavulánico, cefalotina y colistin. En los últimos años existe preocupación por la gran dispersión de los bacilos gramnegativos resistentes a los carbapenémicos (KPC), también causantes de brotes nosocomiales; éstas aumentan la morbimortalidad, los costos hospitalarios y prolon-gan la internación. En nuestro hospital en la Unidad de Cuidados Intensivos (UCI) en el año 2012 tuvimos el primer caso de Infección por SM KPC, constituyéndose un gran desafío médico y de control de infecciones en cuanto al tratamiento, y medidas de control

    An experimental and kinetic modeling study on nitric oxide formation in premixed C3 alcohols flames

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    This study provides new quantitative NO concentrations measurements in n-propanol + air and i-propanol + air flames together with a new combustion kinetic model. The heat flux method was employed to stabilize propyl alcohols flames and the initial gas conditions were set to 323 K, 1 atm, and Ï•=0.7-1.4. Saturated laser-induced fluorescence was employed to measure NO concentration in the post-combustion region. The presented and literature models, namely the POLIMI and Bohon et al. (2018) kinetic mechanisms, were assessed against new experimental data. Experimental results showed a higher NO formation in the thermal zone for n-propanol flames, whereas i-propanol flames indicate a higher amount of NO formed at fuel-rich conditions. Overall among the tested models, the present mechanism exhibited the best agreement in emulating NO experimental profiles; conversely, numerical simulations from the POLIMI model showed significant inconsistencies at fuel-rich conditions and the Bohon et al. (2018) model was unable to reproduce the measured data, notably underpredicting experimental values at all investigated conditions. However, the present model manifested some uncertainties in reproducing NO formation in the prompt region; therefore, in connection with this important aspect, the new experimental data obtained in this work will provide a valid support to further develop more reliable kinetic models

    High-temperature oxidation of propanol isomers in the mixtures with N2O at high Ar dilution conditions

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    This work provides, for the first time, new information regarding the kinetics interaction between N2O and propyl alcohol isomers. To this end, the formation and consumption of atomic oxygen were measured behind the reflected shock waves using Atomic Resonance Absorption Spectroscopy (ARAS) technique for 1–10 ppm n- i-propanol + 10 ppm N2O + Ar mixtures, at 2–3 bar and over a wide temperature range of 1700–3200 K. The Konnov and POLIMI detailed combustion mechanisms were assessed against experimental data and also employed to study the main reactions influencing the oxidation dynamics of fuel mixtures under the investigated conditions. The study highlighted a certain difficulty by the models tested in predicting the formation of atomic oxygen at T < 2000 K. The rate of production and the sensitivity analysis was performed with the attempt to identify the most important reactions involved in the process oxidation for future kinetic model refinements
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