Enzyme unit SI unit, the enzyme unit is discouraged in favour of the katal, the unit recommended by the General Conference on Weights and Measures in 1978 and officially adopted in 1999. One katal is the amount of enzyme that converts 1 mole of substrate per second, so The enzyme unit should not be confused with the international unit (IU); although it is true that both measure chemical activity and that for many enzymes 1 U = 1 IU (because for many enzymes the existing U was adopted as the newer IU), international units can be defined for the biologic activity of
Substance theory is Descartes' substance dualism. Baruch Spinoza denied Descartes' "real distinction" between mind and matter. Substance, according to Spinoza, is one and indivisible, but has multiple "attributes". He regards an attribute, though, as "what we conceive as constituting the [single] essence of substance". The single essence of one substance can be conceived of as material and also, consistently, as mental. What is ordinarily called the natural world, together with all the individuals in it, is immanent in God: hence his famous phrase "deus sive natura" ("God or Nature"). John Locke views substance through a corpuscularian lens where it exhibits two types