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A photooxygenation is a light-induced oxidation reaction in which molecular oxygen is incorporated into the product(s). [1] [2] Initial research interest in photooxygenation reactions arose from Oscar Raab's observations in 1900 that the combination of light, oxygen and photosensitizers is highly toxic to cells. [3]
Oxygen gas can also be produced through electrolysis of water into molecular oxygen and hydrogen. DC electricity must be used: if AC is used, the gases in each limb consist of hydrogen and oxygen in the explosive ratio 2:1. A similar method is the electrocatalytic O 2 evolution from oxides and oxoacids.
The rest of the Earth's crust is formed also of oxygen compounds, most importantly calcium carbonate (in limestone) and silicates (in feldspars). Water-soluble silicates in the form of Na 4 SiO 4, Na 2 SiO 3, and Na 2 Si 2 O 5 are used as detergents and adhesives. [6] Peroxides retain some of oxygen's original molecular structure ((− O-O −).
Singlet oxygen is the common name used for the two metastable states of molecular oxygen (O 2) with higher energy than the ground state triplet oxygen. Because of the differences in their electron shells, singlet oxygen has different chemical and physical properties than triplet oxygen, including absorbing and emitting light at different ...
Two sources inspired Harman: 1) the rate of living theory, which holds that lifespan is an inverse function of metabolic rate which in turn is proportional to oxygen consumption, and 2) Rebeca Gerschman's observation that hyperbaric oxygen toxicity and radiation toxicity could be explained by the same underlying phenomenon: oxygen free radicals.
When oxygen is present, the mitochondria will undergo aerobic respiration which leads to the Krebs cycle. However, if oxygen is not present, fermentation of the pyruvate molecule will occur. In the presence of oxygen, when acetyl-CoA is produced, the molecule then enters the citric acid cycle (Krebs cycle) inside the mitochondrial matrix, and ...
The lowest excited state of the diatomic oxygen molecule is a singlet state. It is a gas with physical properties differing only subtly from those of the more prevalent triplet ground state of O 2 . In terms of its chemical reactivity, however, singlet oxygen is far more reactive toward organic compounds.
The sigmoidal shape of hemoglobin's oxygen-dissociation curve results from cooperative binding of oxygen to hemoglobin. An example of positive cooperativity is the binding of oxygen to hemoglobin. One oxygen molecule can bind to the ferrous iron of a heme molecule in each of the four chains of a hemoglobin molecule.