Investigation into chemistry of new particle formation and growth in subtropical urban environment

The role of different chemical compounds, particularly organics, involved in the new particle formation (NPF) and its consequent growth are not fully understood. Therefore, this study was conducted to investigate the chemistry of aerosol particles during NPF events in an urban subtropical environment. Aerosol chemical composition was measured along with particle number size distribution (PNSD) and several other air quality parameters at five sites across an urban subtropical environment. An Aerodyne compact Time-of-Flight Aerosol Mass Spectrometer (c-TOF-AMS) and a TSI Scanning Mobility Particle Sizer (SMPS) measured aerosol chemical composition and PNSD, respectively. Five NPF events, with growth rates in the range 3.3-4.6 nm, were detected at two sites. The NPF events happened on relatively warmer days with lower humidity and higher solar radiation. Temporal percent fractions of nitrate, sulphate, ammonium and organics were modelled using the Generalised Additive Model (GAM), with a basis of penalised spline. Percent fractions of organics increased after the NPF events, while the mass fraction of ammonium and sulphate decreased. This uncovered the important role of organics in the growth of newly formed particles. Three organic markers, factors f43, f44 and f57, were calculated and the f44 vs f43 trends were compared between nucleation and non-nucleation days. f44 vs f43 followed a different pattern on nucleation days compared to non-nucleation days, whereby f43 decreased for vehicle emission generated particles, while both f44 and f43 decreased for NPF generated particles. It was found for the first time that vehicle generated and newly formed particles cluster in different locations on f44 vs f43 plot and this finding can be used as a tool for source apportionment of measured particles.

Littérature et guerres mondiales en Belgique francophone: champ, contre-chant et hors-champ

info:eu-repo/semantics/published

Primer Seminario Internacional de Orientación Profesional.

Se describen los actos acontecidos en el Primer Seminario Internacional de Orientación Profesional, celebrada en Montecatini-Florencia, Italia, organizado por la Asociación Internacional de Orientación Profesional, en el que se estudiaron algunos de los problemas fundamentales relativos a la Orientación Profesional. Los problemas tratados fueron: 1. La organización, legislación, reglamentación y sostenimiento de la Orientación Profesional. 2. El personal de la Orientación profesional, su preparación, su competencia y su estatuto. 3. Las etapas de la Orientación Profesional. 4. El dosier de Orientación Profesional. 5. La orientación profesional de los deficientes. 6. La orientación Profesional y los emigrados. Sobre cada uno de estos temas se presentaron ponencias por personal especializado en el conocimiento de estas materias y además se hizo una exposición de material de orientación profesional. Asimismo, se abrió un amplio debate sobre los métodos psicotécnicos y su utilidad. Por último se trataron temas relativos al adolescente y la producción y a la formación y preparación del orientador profesional.