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
Tritium in drinking water vary from country to country. Some figures are given below: The American limit is calculated to yield a dose of 4.0 millirems (or 40 microsieverts in SI units) per year. This is about 1.3% of the natural background radiation (roughly 3,000 μSv). The beta particles emitted by the radioactive decay of small amounts of tritium cause chemicals called phosphors to glow. This radioluminescence is used in self-powered lighting devices called betalights, which are used for night illumination of firearm sights, watches, exit signs, map lights, knives and a variety of other devices. Tritium has replaced radioluminescent paint