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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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Journal ArticleDOI
TL;DR: This work addresses intracellular events within the myocyte with particular attention to the role of myoglobin, and asks how the massive and variable flow of oxygen to muscle mitochondria is achieved at near-constant low sarcoplasmic oxygen pressure.
Abstract: Red muscles, despite access to an infinite reservoir of air and drawing their oxygen supply from alveolar air of Po, = 100 torr, actually operate in sustained steady states of volume-average sarcoplasmic oxygen pressure near 3 torr. At these oxygen pressures, sarcoplasmic myoglobin is partially sat­ urated with oxygen; intracellular myoglobin offers an endogenous probe of sarcoplasmic oxygen pressure. The heart and red skeletal muscles can vary their rate of work and their rate of steady state oxygen utilization 20-fold in response to sustained demand. Most (at least 85%) of the oxygen consumed by muscle is used for mitochondrial oxidative phosphorylation (89). That the rate of mitochondrial ATP genesis can also vary 20-fold follows logically. Here we ask how the massive and variable flow of oxygen to muscle mitochondria is achieved at near-constant low sarcoplasmic oxygen pressure. We address intracellular events within the myocyte with particular attention to the role of myoglobin. We report the facts and let them speak and draw inferences as closely as possible to the experimental findings. In passing, we allude to some mathematical or numerical treatments of oxygen transport and diffusion but do not attempt a critical review or analysis. The role of myoglo­ bin in oxygen supply to muscle, pioneered by Millikan (86), is reviewed elsewhere (73, 125, 133, 134). Also, the molecular mechanism of in­ tracellular myoglobin function is discussed in greater detail in an upcoming review (1. B. Wittenberg, B. A. Wittenberg, in preparation).

477 citations

Journal ArticleDOI
14 Feb 2003-Science
TL;DR: The structures of naphthalene dioxygenase are determined that show a molecular oxygen species bound to the mononuclear iron in a side-on fashion and provide the basis for a reaction mechanism and for the high stereospecificity of the reaction catalyzed by naphthaene diodesase.
Abstract: Binding of oxygen to iron is exploited in several biological and chemical processes. Although computational and spectroscopic results have suggested side-on binding, only end-on binding of oxygen to iron has been observed in crystal structures. We have determined structures of naphthalene dioxygenase that show a molecular oxygen species bound to the mononuclear iron in a side-on fashion. In a complex with substrate and dioxygen, the dioxygen molecule is lined up for an attack on the double bond of the aromatic substrate. The structures reported here provide the basis for a reaction mechanism and for the high stereospecificity of the reaction catalyzed by naphthalene dioxygenase.

473 citations

Journal ArticleDOI
TL;DR: A comprehensive review about the versatility of photoelectron spectroscopy to study the especially complex interaction of oxygen with metal surfaces and the nature of the reaction products can be found in this paper.

473 citations

Journal ArticleDOI
Yasuo Takeda1, R. Kanno1, M. Noda1, Y. Tomida1, Osamu Yamamoto1 
TL;DR: In this paper, the cathodic polarization of the electrodes sputtered on yttria stabilized zirconia electrolyte was studied at 800°C in air and the system showed high electrode activity for oxygen reduction.
Abstract: The cathodic polarization of the electrodes sputtered on yttria stabilized zirconia electrolyte was studied at 800°C in air. The system showed high electrode activity for oxygen reduction. The study of the electrode resistance as functions of and temperature revealed that the rate‐determining steps for oxygen reduction were as follows: the charge transfer process for , the dissociation of oxygen molecules on the surface for and , and the oxygen diffusion on the electrode surface for . The marked electrode activity of was explained by the large effective reaction surface area, which is caused by the high oxide ion diffusivity and the high dissociation ability of oxygen molecules. In , the ability of the dissociation of oxygen molecules was considered to be lower than that in . The low activity of Cr‐perovskite electrode was explained by the low diffusivity of oxygen ions.

473 citations

Journal ArticleDOI
TL;DR: Exceptionally active bifunctional catalysts for oxygen electrodes comprising Mn3O4 and Co3O 4 nanoparticles embedded in nitrogen-doped carbon obtained by selective pyrolysis and subsequent mild calcination of manganese and cobalt N4 macrocyclic complexes are reported.
Abstract: Reversible interconversion of water into H2 and O2, and the recombination of H2 and O2 to H2O thereby harnessing the energy of the reaction provides a completely green cycle for sustainable energy conversion and storage. The realization of this goal is however hampered by the lack of efficient catalysts for water splitting and oxygen reduction. We report exceptionally active bifunctional catalysts for oxygen electrodes comprising Mn3O4 and Co3O4 nanoparticles embedded in nitrogen-doped carbon, obtained by selective pyrolysis and subsequent mild calcination of manganese and cobalt N4 macrocyclic complexes. Intimate interaction was observed between the metals and nitrogen suggesting residual M-N(x) coordination in the catalysts. The catalysts afford remarkably lower reversible overpotentials in KOH (0.1 M) than those for RuO2, IrO2, Pt, NiO, Mn3O4, and Co3O4, thus placing them among the best non-precious-metal catalysts for reversible oxygen electrodes reported to date.

470 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20233,516
20226,670
20211,229
20201,164
20191,190
20181,153