Formation of secondary organic aerosols from the ozonolysis of dihydrofurans

In this work we report the study of the ozonolysis of 2,5-dihydrofuran and 2,3-dihydrofuran and the reaction conditions leading to the formation of secondary organic aerosols. The reactions have been carried out in a Teflon chamber filled with synthetic air mixtures at atmospheric pressure and room temperature. The ozonolysis only produced particles in the presence of SO2. Rising relative humidity from 0 to 40% had no effect on the production of secondary organic aerosol in the case of 2,5-dihydrofuran, while it reduced the particle number and particle mass concentrations from the 2,3-dihydrofuran ozonolysis. The water-to-SO2 rate constant ratio for the 2,3-dihydrofuran Criegee intermediate was derived from the secondary organic aerosol (SOA) yields in experiments with different relative humidity values, kH2O/kSO2 = (9.8 ± 3.7) × 10-5. The experimental results show that SO3 may not be the only intermediate involved in the formation or growth of new particles in contrast to the data reported for other Criegee intermediate-SO2 reactions. For the studied reactions, SO2 concentrations remained constant during the experiments, behaving as a catalyst in the production of condensable products. Computational calculations also show that the stabilised Criegee intermediates from the ozonolysis reaction of both 2,5-dihydrofuran and 2,3-dihydrofuran may react with SO2, resulting in the regeneration of SO2 and the formation of low-volatility organic acids.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Formation of secondary organic aerosols from the ozonolysis of dihydrofurans

In this work we report the study of the ozonolysis of 2,5-dihydrofuran and 2,3-dihydrofuran and the reaction conditions leading to the formation of secondary organic aerosols. The reactions have been carried out in a Teflon chamber filled with synthetic air mixtures at atmospheric pressure and room temperature. The ozonolysis only produced particles in the presence of SO2. Rising relative humidity from 0 to 40% had no effect on the production of secondary organic aerosol in the case of 2,5-dihydrofuran, while it reduced the particle number and particle mass concentrations from the 2,3-dihydrofuran ozonolysis. The water-to-SO2 rate constant ratio for the 2,3-dihydrofuran Criegee intermediate was derived from the secondary organic aerosol (SOA) yields in experiments with different relative humidity values, kH2O/kSO2 = (9.8 ± 3.7) × 10-5. The experimental results show that SO3 may not be the only intermediate involved in the formation or growth of new particles in contrast to the data reported for other Criegee intermediate-SO2 reactions. For the studied reactions, SO2 concentrations remained constant during the experiments, behaving as a catalyst in the production of condensable products. Computational calculations also show that the stabilised Criegee intermediates from the ozonolysis reaction of both 2,5-dihydrofuran and 2,3-dihydrofuran may react with SO2, resulting in the regeneration of SO2 and the formation of low-volatility organic acids.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Oseltamivir-Resistant Pandemic (H1N1) 2009 Virus, Mexico

During May 2009–April 2010, we analyzed 692 samples of pandemic (H1N1) 2009 virus from patients in Mexico. We detected the H275Y substitution of the neuraminidase gene in a specimen from an infant with pandemic (H1N1) 2009 who was treated with oseltamivir. This virus was susceptible to zanamivir and resistant to adamantanes and oseltamivir

Resultados da participação do Paraguai no estudo nutritionDay 2021

Each year, nutritionDay (nDay) provides de opportunity to analyze the intention to optimize nutritional and metabolic support and compare results with those obtained in the region and in the world. The aim of this study is to present the most relevant results of nDay in inpatient hospital wards and Intensive Care Units in 2021.El nutritionDay (nDay) ayuda a analizar cada año la intención de optimizar el soporte nutricional y metabólico, y comparar los resultados con los obtenidos en la región y en el mundo. El objetivo de este estudio es presentar los resultados más relevantes del nDay en las salas de internación de hospitales y unidades de cuidados intensivos (UCI) en 2021.O nutritionDay (nDay) ajuda a analisar a cada ano a intenção de otimizar o suporte nutricional e metabólico e comparar os resultados com os obtidos na região e no mundo. O objetivo deste estudo é apresentar os resultados mais relevantes do nDay nas unidades de internação hospitalar e unidades de terapia intensiva (UTI) em 2021

New particle formation from the reactions of ozone with indene and styrene

This work reports the experimental study of the ozonolysis of indene in the presence of SO2 and the reaction conditions leading to the formation of secondary aerosols. The reactions have been carried out in a Teflon chamber filled with synthetic air mixtures at atmospheric pressure and room temperature. As in the case of styrene, SO2 plays a key role in the oxidation of the Criegee intermediates and enhances the formation of particulate matter. Thus, for the ozonolysis of indene, nucleation was observed for reacted indene concentrations above (4.5 ± 0.8) × 1011 molecule cm−3 in the absence of SO2 while new particle formation was observed for concentrations one order of magnitude lower, (3 ± 1) × 1010 molecule cm−3, in the presence of SO2. Within the detection limit of the system, SO2 concentrations remained constant during the experiments. The formation of secondary aerosols in the smog chamber was inhibited by H2O and so the potential formation of secondary aerosols under atmospheric conditions depends on the concentration of SO2 and relative humidity. Computational calculations have been performed for the ozonolysis of both indene and styrene in the presence of SO2 and water to identify the reaction channels and species responsible for new particle formation. The release of SO3 and its subsequent conversion into H2SO4 from the reaction of the Criegee intermediate H2COO in the ozonolysis of styrene makes this aromatic have a high potential of aerosol formation in the atmosphere. On the other hand, quantitative conversion of SO2 into SO3 does not occur following the ozonolysis of indene.Fil: Bracco, Larisa Laura Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Tucceri, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Escalona, Alba. Universidad de Castilla-La Mancha; EspañaFil: Díaz de Mera, Yolanda. Universidad de Castilla-La Mancha; EspañaFil: Aranda Rubio, Alfonso. Universidad de Castilla-La Mancha; EspañaFil: Rodríguez, Ana M.. Universidad de Castilla-La Mancha; EspañaFil: Rodríguez, Diana. Universidad de Castilla-La Mancha; Españ