Kinetic isotope effect effects, while "k"/"k" ~ 1.15-1.3 are typical for β secondary kinetic isotope effect. For reactants containing several isotopically-substituted β-hydrogen atoms, the observed isotope effect is often the result of several H/D's at the β position acting in concert. In these cases, the effect of each isotopically-labeled atom is multiplicative, and cases where "k"/"k" > 2 are not uncommon. The following simple expressions relating deuterium and tritium kinetic isotope effects, which are also known as the Swain equation (or the Swain-Schaad-Stivers equations), can be derived from the general expression given above using some simplifications: i.e., In deriving these expressions, the reasonable
Heavy water neutrinos, as well as a non-absorbent moderator medium to preserve free neutrons from this reaction, until they can be absorbed by an easily detected neutron-activated isotope. Heavy water is employed as part of a mixture with HO for a common and safe test of mean metabolic rate in humans and animals undergoing their normal activities. Tritium is the active substance in self-powered lighting and controlled nuclear fusion, its other uses including autoradiography and radioactive labeling. It is also used in nuclear weapon design for boosted fission weapons and initiators. Some tritium is created in heavy water moderated reactors when deuterium