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The vaporized getter, usually a volatile metal, instantly reacts with any residual gas, and then condenses on the cool walls of the tube in a thin coating, the getter spot or getter mirror, which continues to absorb gas. This is the most common type, used in low-power vacuum tubes. Non-evaporable getter (NEG) [8]
The best known explanation of the oxygen effect is the oxygen fixation hypothesis developed by Alexander in 1962, [9] which posited that radiation-induced non-restorable or "fixed" nuclear DNA lesions are lethal to cells in the presence of diatomic oxygen. [10] [11] Recent hypotheses include one based on oxygen-enhanced damage from first ...
The original paper by Ellingham explicitly to the reduction of both oxygen and sulfur by metallurgical processes, [1] and anticipated the use of such diagrams for other compounds, including chlorides, carbides, and sulfates. The concept is generally useful for studying the comparative stability of compounds across a range of partial pressures ...
Despite the bactericidal effects of ethanol, acidifying effects of fermentation, and low oxygen conditions of industrial alcohol production, bacteria that undergo lactic acid fermentation can contaminate such facilities because lactic acid has a low pKa of 3.86 to avoid decoupling the pH membrane gradient that supports regulated transport.
Methanol cross-over and/or its effects can be alleviated by (a) developing alternative membranes (e.g. [6] [7]), (b) improving the electro-oxidation process in the catalyst layer and improving the structure of the catalyst and gas diffusion layers (e.g. [8]), and (c) optimizing the design of the flow field and the membrane electrode assembly ...
Carotenoids, tocopherols, and plastoquinones contained in chloroplasts quench singlet oxygen and protect against its toxic effects. Oxidized products of β-carotene arising from the presence of singlet oxygen act as second messengers that can either protect against singlet oxygen induced toxicity or initiate programmed cell death.
The oxygen window effect in decompression is described in diving medical texts and the limits reviewed by Van Liew et al. in 1993. [ 1 ] [ 11 ] When living animals are in steady state, the sum of the partial pressures of dissolved gases in the tissues is usually less than atmospheric pressure, a phenomenon known as the "oxygen window", "partial ...
The large size of many arthropods in the Carboniferous period, when the oxygen concentration in the atmosphere reached 35%, has been attributed to the limiting role of diffusion in these organisms' metabolism. [14] But J.B.S. Haldane's essay [15] points out that it would only apply to insects.