Topic
Oxygen
About: Oxygen is a research topic. Over the lifetime, 48149 publications have been published within this topic receiving 1113788 citations. The topic is also known as: O & Oxygen.
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TL;DR: In this paper, a model of fast heating of nitrogen?oxygen mixtures excited by a gas discharge in a broad range of reduced electric fields E/N is presented, where the main contribution to gas heating occurs due to dissociation reactions by electron impact of O2 molecules and due to processes of quenching of electronically excited N2(B?3?g, C?3?u, ) molecules by oxygen and excited O(1D) atoms by nitrogen.
Abstract: A model of fast heating of nitrogen?oxygen mixtures excited by a gas discharge in a broad range of reduced electric fields E/N is presented. It is shown that in air at E/N ? 200?Td the main contribution to gas heating occurs due to dissociation reactions by electron impact of O2 molecules and due to processes of quenching of electronically excited N2(B?3?g, C?3?u, ) molecules by oxygen and excited O(1D) atoms by nitrogen. At E/N > 400?Td, dissociation reactions by electron impact of N2 molecules are dominant as well as the processes involving charged particles. The fraction of discharge energy converted to fast gas heating does not exceed 40%. An analysis of the experimental data on fast air heating in discharges at high reduced electric fields E/N is given.It was shown that, in a broad range of reduced electric fields, a fixed fraction of discharge power ?E spent on the excitation of electronic degrees of freedom, ionization and dissociation of molecules is converted to fast heating of nitrogen?oxygen mixtures. In air, the value of ?E is about 30 ? 3%. The value of ?E diminishes with decreasing share of oxygen in a mixture. The significant role of heat release in the pooling reactions of molecules for fast gas heating in pure nitrogen and in nitrogen with small admixtures of oxygen is demonstrated. The simulation results agree with experimental data at E/N < 200?Td within the range of oxygen content ? = 0?20%.
299 citations
TL;DR: Cerium−zirconium mixed oxides (CexZr(1-x)O2), precalcined at 900 °C in dry air, were supplied by Rhodia Terres Rares as monophasic solid solutions as mentioned in this paper.
Abstract: Cerium−zirconium mixed oxides (CexZr(1-x)O2), precalcined at 900 °C in dry air, were supplied by Rhodia Terres Rares as monophasic solid solutions. Introduction of some zirconium atoms in the ceria...
299 citations
TL;DR: In this paper, the corrosion properties of pure iron and the alloys Fe-0.5Cu and Fe-3.4Cu are investigated during several wet/dry transitions, and the corrosion potential is measured with a Kelvin probe without touching the surface under investigation.
298 citations
TL;DR: In this article, the effect of liquid-phase oxidation on the texture and surface properties of carbon nanofibers has been studied using XRD, TEM, SEM, N2-physisorption, TGA-MS, XPS and acid-base titrations.
296 citations
TL;DR: The singlet oxygen reaction rate was the highest in β-carotene, followed by tocopherol, riboflavin, vitamin D, and ascorbic acid, which means that Vitamins are easily oxidized by ROS, especially singinglet oxygen.
Abstract: Reactive oxygen species (ROS) are formed enzymatically, chemically, photochemically, and by irradiation of food. They are also formed by the decomposition and the inter-reactions of ROS. Hydroxy radical is the most reactive ROS, followed by singlet oxygen. Reactions of ROS with food components produce undesirable volatile compounds and carcinogens, destroy essential nutrients, and change the functionalities of proteins, lipids, and carbohydrates. Lipid oxidation by ROS produces low molecular volatile aldehydes, alcohols, and hydrocarbons. ROS causes crosslink or cleavage of proteins and produces low molecular carbonyls from carbohydrates. Vitamins are easily oxidized by ROS, especially singlet oxygen. The singlet oxygen reaction rate was the highest in β-carotene, followed by tocopherol, riboflavin, vitamin D, and ascorbic acid.
296 citations