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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 ...
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.
Metallography allows the metallurgist to study the microstructure of metals. A micrograph of bronze revealing a cast dendritic structure Al-Si microstructure. Microstructure is the very small scale structure of a material, defined as the structure of a prepared surface of material as revealed by an optical microscope above 25× magnification. [1]
The model describes how dissolved oxygen (DO) decreases in a river or stream along a certain distance by degradation of biochemical oxygen demand (BOD). The equation was derived by H. W. Streeter, a sanitary engineer, and Earle B. Phelps , a consultant for the U.S. Public Health Service , in 1925, based on field data from the Ohio River .
If the concentration of oxygen increases, pyruvate is instead converted to acetyl CoA, used in the citric acid cycle, and undergoes oxidative phosphorylation. Per glucose, 10 NADH and 2 FADH 2 are produced in cellular respiration for a significant amount of proton pumping to produce a proton gradient utilized by ATP Synthase. While the exact ...
The oxygen enhancement ratio (OER) or oxygen enhancement effect in radiobiology refers to the enhancement of therapeutic or detrimental effect of ionizing radiation due to the presence of oxygen. This so-called oxygen effect [1] is most notable when cells are exposed to an ionizing radiation dose. The OER is traditionally defined as the ratio ...
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 ...