Search results for "Ozono"

Two known therapies could be useful as adjuvant therapy in critical patients infected by COVID-19☆

2020

Pneumonia caused by coronavirus, which originated in Wuhan, China, in late 2019, has been spread around the world already becoming a pandemic. Unfortunately, there is not yet a specific vaccine or effective antiviral drug for treating COVID-19. Many of these patients deteriorate rapidly and require intubation and are mechanically ventilated, which is causing the collapse of the health system in many countries due to lack of ventilators and intensive care beds. In this document we review two simple adjuvant therapies to administer, without side effects, and low cost that could be useful for the treatment of acute severe coronavirus infection associated with acute respiratory syndrome (SARS-C…

Identification of organic hydroperoxides and hydroperoxy acids in secondary organic aerosol formed during the ozonolysis of different monoterpenes an…

2009

On-line ion trap mass spectrometry (ITMS) enables the real-time characterization of reaction products of secondary organic aerosol (SOA). The analysis was conducted by directly introducing the aerosol particles into the ion source. Positive-ion chemical ionization at atmospheric pressure (APCI(+)) ITMS was used for the characterization of constituents of biogenic SOA produced in reaction-chamber experiments. APCI in the positive-ion mode usually enables the detection of [M+H](+) ions of the individual SOA components. In this paper the identification of organic peroxides from biogenic volatile organic compounds (VOCs) by on-line APCI-ITMS is presented. Organic peroxides containing a hydroper…

Secondary brown carbon formation via the dicarbonyl imine pathway: nitrogen heterocycle formation and synergistic effects.

2016

Dicarbonyls are known to be important precursors of so-called atmospheric brown carbon, significantly affecting aerosol optical properties and radiative forcing. In this systematic study we report the formation of light-absorbing nitrogen containing compounds from simple 1,2-, 1,3-, 1,4-, and 1,5-dicarbonyl + amine reactions. A combination of spectrophotometric and mass spectrometric techniques was used to characterize reaction products in solutions mimicking atmospheric particulates. Experiments with individual dicarbonyls and dicarbonyl mixtures in ammonium sulfate and glycine solutions demonstrate that nitrogen heterocycles are common structural motifs of brown carbon chromophores formed…

2016

Abstract. We found that ambient and laboratory-generated secondary organic aerosols (SOA) form substantial amounts of OH radicals upon interaction with liquid water, which can be explained by the decomposition of organic hydroperoxides. The molar OH yield from SOA formed by ozonolysis of terpenes (α-pinene, β-pinene, limonene) is  ∼  0.1 % upon extraction with pure water and increases to  ∼  1.5 % in the presence of Fe2+ ions due to Fenton-like reactions. Upon extraction of SOA samples from OH photooxidation of isoprene, we also detected OH yields of around  ∼  0.1 %, which increases upon addition of Fe2+. Our findings imply that the chemical reactivity and aging of SOA particles is strongl…

Synthesis and characterisation of peroxypinic acids as proxies for highly oxygenated molecules (HOMs) in secondary organic aerosol

2018

Abstract. Peroxy acids were recently found to be involved in new particle formation in the atmosphere and could also substantially contribute towards particle toxicity. However, a lack of suitable analytical methods for the detection and characterisation of peroxy acids in the particle phase is currently hindering the quantitative investigation of their contribution to these important atmospheric processes. Further development of appropriate techniques and relevant standards is therefore urgently needed. In this study, we synthesised three peroxypinic acids, developed a liquid chromatography separation method and characterised them with tandem mass spectrometry. The observed fragmentation p…

Unambiguous identification of esters as oligomers in secondary organic aerosol formed from cyclohexene and cyclohexene/α-pinene ozonolysis

2007

Abstract. The build-up of oligomeric compounds during secondary organic aerosol (SOA) formation is subject of atmospheric research since several years. New particle formation and especially the SOA mass yield might be influenced significantly by oligomer formation. However, the chemical nature of observed oligomers and their formation pathways are still unclear. In this paper, the structural characterization of certain dimeric compounds (esters) formed during the ozonolysis of cyclohexene and cyclohexene/α-pinene mixtures are presented. The identification is based on the comparison of the mass spectra and the retention times (LC) of the oligomeric products with synthesized reference compoun…

Estudio anatómico-histológico de las flores del endemismo Lamottea diania (Asteraceae) y de los efectos del ozono troposférico sobre su desarrollo.

2016

"Estudio anatómico-histológico de las flores del endemismo Lamottea diania (Asteraceae) y de los efectos del ozono troposférico sobre su desarrollo". Lilloa 53 (2). Plantas del endemismo Lamottea diania se expusieron en cámaras OTC (Open Top Chambers) a aire ambiente filtrado y a aire ambiente no filtrado más 30 ppb de ozono para observar el efecto de este contaminante sobre el desarrollo de sus flores, particularmente sobre su androceo. Hemos comprobado, mediante estudios de microscopía óptica y electrónica, que el ozono afecta el proceso de desarrollo y maduración de los estambres y del polen. Las anteras se ven afectadas, en unos casos al abortar algunos estambres en su desarrollo y, en …

Volatility of secondary organic aerosol during OH radical induced ageing

2011

The aim of this study was to investigate oxidation of SOA formed from ozonolysis of <i>α</i>-pinene and limonene by hydroxyl radicals. This paper focuses on changes of particle volatility, using a Volatility Tandem DMA (VTDMA) set-up, in order to explain and elucidate the mechanism behind atmospheric ageing of the organic aerosol. The experiments were conducted at the AIDA chamber facility of Karlsruhe Institute of Technology (KIT) in Karlsruhe and at the SAPHIR chamber of Forchungzentrum Jülich (FZJ) in Jülich. A fresh SOA was produced from ozonolysis of <i>α</i>-pinene or limonene and then aged by enhanced OH exposure. As an OH radical source in…

Experimental and theoretical study of stereoelectronic and H-bond control of reactivity in α- and β-methyl d-glucopyranoside ozonolysis

1998

Abstract The topography of the molecular electrostatic potential (MEP) of α and β anomers of methyl d -glucopyranosides has been used to analyze the reactivity of these species towards electrophilic attack and to complete the results we obtained during the ozonation reaction. Molecular mechanics (MM) and molecular dynamics (MD) simulations have been performed to screen the conformational space of α- and β-methyl d -glucopyranosides in order to determine the chair conformations which correspond to a global minimum energy conformation. Density Functional Theory (DFT) (Faststructure) and PM3 (semiempirical) calculations have been carried out to refine the geometries of the 4 C 1 and 1 C 4 chai…

Aging of biogenic secondary organic aerosol via gas-phase OH radical reactions

2012

The Multiple Chamber Aerosol Chemical Aging Study (MUCHACHAS) tested the hypothesis that hydroxyl radical (OH) aging significantly increases the concentration of first-generation biogenic secondary organic aerosol (SOA). OH is the dominant atmospheric oxidant, and MUCHACHAS employed environmental chambers of very different designs, using multiple OH sources to explore a range of chemical conditions and potential sources of systematic error. We isolated the effect of OH aging, confirming our hypothesis while observing corresponding changes in SOA properties. The mass increases are consistent with an existing gap between global SOA sources and those predicted in models, and can be described b…