Search results for "ozone"
showing 10 items of 300 documents
Application of time-of-flight aerosol mass spectrometry for the online measurement of gaseous molecular iodine.
2012
Here we present a new application of a time-of-flight aerosol mass spectrometer (TOF-AMS) for the measurement of atmospheric trace gases in real-time. Usually, TOF-AMS instruments are not sensitive to gas-phase species due to the aerodynamic particle focusing inlet system which reduces the gas phase species by a factor of about 10(7) relative to the particle phase. This efficient removal of the gas phase and the resulting high relative enrichment of particles is one reason for the very high sensitivity of TOF-AMS instruments for particle phase compounds (detection limits in the sub-μg/m(3)-range for online measurements with 1 min integration time), which allows application of the instrument…
Atmospheric protein chemistry influenced by anthropogenic air pollutants: nitration and oligomerization upon exposure to ozone and nitrogen dioxide
2017
The allergenic potential of airborne proteins may be enhanced via post-translational modification induced by air pollutants like ozone (O3) and nitrogen dioxide (NO2). The molecular mechanisms and kinetics of the chemical modifications that enhance the allergenicity of proteins, however, are still not fully understood. Here, protein tyrosine nitration and oligomerization upon simultaneous exposure of O3 and NO2 were studied in coated-wall flow-tube and bulk solution experiments under varying atmospherically relevant conditions (5–200 ppb O3, 5–200 ppb NO2, 45–96% RH), using bovine serum albumin as a model protein. Generally, more tyrosine residues were found to react via the nitration pathw…
Size patterns through time: the case of the Early Jurassic ammonite radiation
2002
The shell size of 1236 ammonite species representing all known Early Jurassic faunas is analyzed. Size patterns are studied for the entire period and then at the biozone scale for the first four stages of the Jurassic (28 Myr), during which ammonites recovered from the crisis at the Triassic/Jurassic (T/J) boundary. Our analysis reveals that (1) a size continuum (normal distribution from “dwarfs” to “giants”) exists for all Early Jurassic ammonites; (2) although there are no sustained trends (e.g., no Cope's rule), the succession is not monotonous and patterns may differ conspicuously from one biozone to the next; and (3) increases and decreases in size range are the most frequent evolution…
Existe-t-il une crise au passage Lias-Dogger chez les ammonites? Approche morphometrique par quantification de la disparite morphologique
2001
Abstract Morphological changes observed in ammonites at the Lias-Dogger (Toarcian-Aalenian) boundary are analyzed here. The study covers all known ammonites worldwide over some 2 m.y. (the last two biozones of the Toarcian: Pseudoradiosa and Aalensis and the first biozone of the Aalenian: Opalinum). Ammonite taxonomy at this boundary is still open to question, the main disagreements being over groupings at family or super-family level. The evolutionary schema developed by Tintant and Mouterde [1981] shows two main sets of Ammonitina for the time: (1) the dominant Hammatocerataceae (Graphoceratidae+Hammatoceratidae) and (2) the final representatives of the Hildocerataceae. Two conservative a…
Un exemple de spéciation lié à l'eustatisme: l'apparition précoce de Schackoina cabri (foraminifère planctonique mésogéen)
1997
Investigation of planktic foraminifers from the Lower Aptian of the Vocontian Basin (SE France) reveals that Schackoina cabri makes a very discrete first appearance in the Weissi ammonite zone and not in the Deshayesi zone, i.e. before the global anoxic event OAE 1a and not after as was accepted in the literature. This discovery seems to support the recent model whereby speciation of planktic foraminifers occurred in marine lowstands and their real expansion during the ensuing sea-level rise.
Variations in Jurassic echinoid biodiversity at ammonite zone levels: Stratigraphical and palaeoecological significance
2020
After a relatively low but stable phase of taxonomic diversity during the Lias (Lower Jurassic), echinoids diversity strongly increases from Aalenian (Dogger-Middle Jurassic) to Kimmeridgian (Malm-Late Jurassic) and a conspicuous crisis takes place in Tithonian times, before the end of the Jurassic. During these major phases, minor decreases in diversity correspond with regressions (sea-level falls), mainly in the Middle Bathonian (Middle Jurassic). From the Aalenian to Callovian, the average duration of irregular echinoid species is about 3.8 m.y. whereas it is about 5.5 m.y. for the regular ones; the later value corresponding to the average duration of a Jurassic. From Callovian to Tithon…
World distribution of middle Jurassic ammonites (Upper Aalenian to Middle Bathonian): relationships between biodiversity and palaeogeography
2004
Abstract The break up of the Pangea takes place in the Jurassic; the palaeoceanographic consequences are the opening of seaways, particularly at the place of the future Atlantic and Indian oceanic areas. During the Toarcian, and from the late Aalenian to the middle Bathonian, the so-called “Hispanic corridor” (or “Atlantic seaway”) exists between the “western Tethys” and the “American Pacific border”, through the “Caribbean Tethys”. Two additional seaways which play as by-passes of the Pangea are proposed, one along the northern border of Laurasia (Boreal sea), and a second along the southern border of Gondwana (South Pacific Sea); however, if these two last could be effectively used for fa…
Ozone therapy in oxidative stress disorders and evaluation of C-reactive proteins [abstract]
2018
It is well recognized that oxidative stress and oxidative damage to DNA, RNA, protein and cell membranes is responsible for early ageing and lifestyle disorders. In various pathological conditions the main problem is related to a rapid increase in the cellular ROS concentration that exceeds the capacity of the cell to eliminate them. ROS derived from the ozone therapy can exert its protective effects by means of an oxidative preconditioning, stimulating and/or preserving the endogenous antioxidant systems. The aim of this paper is to evaluate the ozone effects, in a preliminary clinical treatment in the oxidative stress disorders. We enrolled 12 patients having type2 diabetes who were prone…
Extra Corporeal Oxygenation & Ozonation, EBOO & AQUAPHERESIS method of Ozone Therapy, Clinical Application in Chronic Diseases [abstract]
2018
Introduction: The top 10 causes of death around the world are usually ranked with heart diseases, cancers, drugs/medication/iatrogenic chemicals, strokes etc. These are totally detectable, predictable, avoidable, preventable because it is classified as non-communicable diseases. Acute diseases are denoted by acute inflammation which has intensive cell-cell communications, resulting intensive repair rebuilding rehabilitation and it is life extending. Often it is self defensive and we over come it. The real culprit for chronic diseases is chronic inflammations, denoted by constant & silent, undetectable & insensible lost of cell-cell signaling, basement membrane disease, tight junctio…
Oxidation of oxalate ion in aqueous suspensions of TiO2 by photocatalysis and ozonation
2005
Abstract Oxalate anion has been oxidized in aqueous alkaline solution by using ozonation and photocatalysis in the presence of TiO 2 . A batch annular reactor has been used for carrying out reactivity runs in the presence of air/ozone, air/ozone/near UV irradiation, air/ozone/TiO 2 , air/near UV-irradiated TiO 2 and air/ozone/near UV-irradiated TiO 2 . The Langmuir–Hinshelwood kinetic model adequately describes the photocatalytic results obtained at different reaction conditions and allows determining the values of the kinetic and equilibrium adsorption constants. The contemporary presence of photocatalysis and ozonation shows a significant improvement of the process performance as the oxid…