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: These findings not only propose a novel PMS activation mechanism in terms of simultaneous PMS oxidation and reduction for the production of nonradical and radical species but also provide a valuable insight for the development of efficient metal-free catalysts through nonmetal doping toward the persulfate-based environmental cleanup.
Abstract: Oxygen-doped graphitic carbon nitride (O-CN) was fabricated via a facile thermal polymerization method using urea and oxalic acid dihydrate as the graphitic carbon nitride precursor and oxygen source, respectively. Experimental and theoretical results revealed that oxygen doping preferentially occurred on the two-coordinated nitrogen positions, which create the formation of low and high electron density areas resulting in the electronic structure modulation of O-CN. As a result, the resultant O-CN exhibits enhanced catalytic activity and excellent long-term stability for peroxymonosulfate (PMS) activation toward the degradation of organic pollutants. The O-CN with modulated electronic structure enables PMS oxidation over the electron-deficient C atoms for the generation of singlet oxygen (1O2) and PMS reduction around the electron-rich O dopants for the formation of hydroxyl radical (•OH) and sulfate radical (SO4•-), in which 1O2 is the major reactive oxygen species, contributing to the selective reactivity of the O-CN/PMS system. Our findings not only propose a novel PMS activation mechanism in terms of simultaneous PMS oxidation and reduction for the production of nonradical and radical species but also provide a valuable insight for the development of efficient metal-free catalysts through nonmetal doping toward the persulfate-based environmental cleanup.
395 citations
395 citations
TL;DR: If a person is subjected to progressively increasing work loads, there is a linear relation between work load and oxygen uptake until the maximal oxygen uptake is reached.
Abstract: KNOWLEDGE of how oxygen is transported from the ambient air to the tissue cells of the body is essential to an understanding of the mechanisms by which the body adapts to the oxygen demands of muscular exercise. The requirement of oxygen by the various tissue cells of the body is met by the combined cardiovascular and pulmonary systems, which function as a unit termed the oxygen transport system of the body. If a person is subjected to progressively increasing work loads, there is a linear relation between work load and oxygen uptake until the maximal oxygen uptake is reached. Heavier . . .
393 citations
TL;DR: FMN and flavodoxin are shown to cause both univalent and divalent reductions of oxygen, and the reduction of oxygen by native milk xanthine oxidase may well be a function of its non-heme iron centers.
393 citations
TL;DR: The construction, operation and calibration of an improved form of a Clark oxygen electrode that shows a rapid response to change in oxygen concentration and is capable of measuring rates of oxygen evolution (or uptake) of up to 4 μmoles oxygen per minute is described.
Abstract: Summary
The construction, operation and calibration of an improved form of a Clark oxygen electrode are described in detail The electrode shows a rapid response (1–5 seconds) to change in oxygen concentration and is capable of measuring rates of oxygen evolution (or uptake) of up to 4 μmoles oxygen per minute The use of a pair of electrodes to measure the oxygen evolution of choloroplasts at high intensity of illumination is described
392 citations