Search results for "ozone"
showing 10 items of 300 documents
Impact of Manaus City on the Amazon Green Ocean atmosphere: Ozone production, precursor sensitivity and aerosol load
2010
As a contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia – Cooperative LBA Airborne Regional Experiment (LBA-CLAIRE-2001) field campaign in the heart of the Amazon Basin, we analyzed the temporal and spatial dynamics of the urban plume of Manaus City during the wet-to-dry season transition period in July 2001. During the flights, we performed vertical stacks of crosswind transects in the urban outflow downwind of Manaus City, measuring a comprehensive set of trace constituents including O3, NO, NO2, CO, VOC, CO2, and H2O. Aerosol loads were characterized by concentrations of total aerosol number (CN) and cloud condensation nuclei (CCN), and by light scattering proper…
Importance of the toxicological tests in the application and safety of ozone therapy
2018
Until today, there is not any official registry of the different routes of systemic ozone therapy. With the aim to prove the safety of this therapy, several ways of ozone (O3) applications were evaluated, such as rectal insufflation (RI), major autohemotherapy (M-AHT) and intraperitoneal application (IP). For RI, some toxicological tests were performed such as: acute, sub-chronic, mutagenic (bone marrow chromosomic aberrations and micronucleus), teratogenic and irritation studies (at 40 mg/L and 10 mL during 15 days). For M-AHT, acute toxicological (in rats with 21, 47 and 64 mg/L and a volume of 2 mL with daily evaluation up to 15 days) and mutagenic (chromosomal aberration analysis, micr…
New tracer compounds for secondary organic aerosol formation from β-caryophyllene oxidation
2013
Abstract Five products from β-caryophyllene oxidation (β-caryophyllonic acid (I), 3,3-dimethyl-2-(3-oxobutyl)cyclobutanecarboxylic acid (βCA198) (II), β-nocaryophyllonic acid (III), β-caryophyllinic acid (IV), and 2-(2-carboxyethyl)-3,3-dimethylcyclobutanecarboxylic acid (βCA200) (V)) were synthesized and their structures confirmed by nuclear magnetic resonance spectroscopy. Reaction chamber experiments with β-caryophyllene at two different ozone mixing ratios were performed and the carboxylic acid oxidation products in the particle phase were characterized by APCI–MS and HPLC–ESI–MS. All five synthesized acids were found as β-caryophyllene oxidation products in the reaction chamber aerosol…
Response to ozone in two lettuce varieties on chlorophyll a fluorescence, photosynthetic pigments and lipid peroxidation.
2004
The effect of different O3 concentrations on two lettuce (Lactuca sativa L.) varieties (Valladolid and Morella) was investigated through chlorophyll (Chl) a fluorescence parameters, photosynthetic pigments (Chl a, b and total carotenoid), lipid peroxidation and crop yield. Ozone fumigation caused: a decrease in maximum quantum yield of photosystem II (PSII) photochemistry (Fv/Fm) in mature leaves, a reduction in the non-cyclic electron flow (phiPSII) and a lower capacity to reoxidize the QA pool (qP). These reductions were significant in the Valladolid var. but not in the Morella var. A significant decrease in Chl a, b and in the total carotenoids was observed in the Valladolid var. but not…
Photocatalytic ozonation: Maximization of the reaction rate and control of undesired by-products
2015
Abstract In the so-called photocatalytic ozonation (PO) synergistic effects between photocatalysis and ozonation enhance the rate of oxidation of organic compounds, therefore this integrated process is very promising for use in water treatment. In the present work, it is demonstrated that the improvement that can be obtained by the integrated process in comparison with the uncoupled processes depends on the relative weight between photocatalysis and ozonation. In this respect, it has been found that a relatively low rate of photocatalysis (0.3 times the rate of ozonation) is sufficient to get the highest synergy and to maximize the performances in the oxidation of formate, the adopted model…
Glutathione-dependent defence system and monooxygenase enzyme activities in Arctic charr Salvelinus alpinus (L.) exposed to ozone
2000
Abstract One of the major obstacles of the increasing usage of ozone in aquaculture is the lack of relevant risk assessment in culture conditions. Before the apparent advantages of ozonation can be utilised efficiently, the safety margins and biological basis of ozone toxicity should be assessed. In this research, 1-year-old Arctic charr ( Salvelinus alpinus (L.)) were exposed to an ozone concentration high enough to inactivate Aeromonas sp. bacteria in freshwater, but too low to be directly lethal to the fish themselves. The effects of ozone exposure on the activity of glutathione-dependent antioxidant enzymes and monooxygenase reactions were studied in blood and in liver. The fish were ac…
Reactions of Peroxides on Solid Surfaces
2014
This article describes the different roles that solid surfaces play in heterogeneous reactions involving peroxides, namely, (i) the solid surface interacts with the peroxide in the absence of any other substrate, (ii) the solid surface promotes the reaction activating either the peroxide or the substrate, (iii) the peroxide forms part of the solid active surface, and (iv) the substrate forms part of the active surface. The chapter covers reactions involving peroxides or discrete peroxydic transient species on solid surfaces or at solid–liquid and solid–gas interfaces, and provides general descriptions of different solid materials, details on reaction conditions, and synthetic procedures for…
TEMPERATURE DEPENDENCE OF THE OZONE ABSORPTION KINETICS IN AQUEOUS PHENOL SOLUTIONS
1978
(1978). TEMPERATURE DEPENDENCE OF THE OZONE ABSORPTION KINETICS IN AQUEOUS PHENOL SOLUTIONS. Chemical Engineering Communications: Vol. 2, No. 4-5, pp. 219-221.
On the electrochemical reduction of carbon dioxide and ethylene
1973
Die gemeinsame Elektrolyse von Athylen (I) und Kohlendioxid (II) liefert je nach den angewandten Bedingungen Mischungen aus Oxalsaure (III) und Bemsteinsaure (IV).
On the occurrence of ClO in cirrus clouds and volcanic aerosol in the tropopause region
1997
Airborne observations during descents of the ER-2 through layers of volcanic aerosol (Mount Pinatubo eruption of 1991) and a cirrus cloud are utilized to study the the abundance of ClO and its relation to aerosol surface area in the midlatitude tropopause region. During a cirrus event near the tropopause ClO mixing ratios up to 2.7 pptv were detected and near the tropopause ClO levels from a few to 70 pptv were found. These measurements are associated with large experimental uncertainties but demonstrate the possible presence of ClO inside cirrus clouds and near the tropopause. Model calculations show that possible enhancements of ClO by heterogeneous chemistry on cirrus cloud particles cou…