Lastly, parietal cells synthesizedand secrete intrinsic factor which aids in the absorption of vitamin B12 by the ileum. Chief cells (B or arrow)are located, in cluster, at the base of the glands. They synthesize and secret hydrolytic enzymes, which areactivated at acid pH. These enzymes include gastric lipase, rennin and pepsin, which is secreted aspepsinogen and activated in the lumen. Pepsin hydrolyzes proteins. Rennin breaks down milk proteins andlipase initiates the digestion of fats.
A basis set in theoretical and computational chemistry is a set of functions (called basis functions) which are combined in linear combinations (generally as part of a quantum chemical calculation) to create molecular orbitals.
In mathematics, a set of elements (vectors) in a vector space V is called a basis, or a set of basis vectors, if the vectors are linearly independent and every vector in the vector space is a linear combination of this set. In more general terms, a basis is a linearly independent spanning set. Given a basis of a vector space V, every element of V can be expressed uniquely as a linear combination of basis vectors, whose coefficients are referred to as vector coordinates or components.