1. Petroleum refinery process in which large heavy oil molecules are broken down into smaller ones. If conducted only with the application of heat, it is called thermal cracking. If a catalyst is also used, it is called catalytic cracking. If hydrogen is used in addition to heat and catalysts, it is called hydrocracking. 2. Deciphering of a code or encrypted data.
Vitamin D3 is the form of vitamin D called cholecalciferol. Cholecalciferol is the most widely known of the vitamin D series and is a fat soluble vitamin that is stored to some degree in the body. It is used as a dietary supplement and for the treatment and prevention of vitamin D deficiency.
Vitamin D3 (cholecalciferol) is the type produced in the body in response to exposure to the sun's ultraviolet B rays. 1  Vitamin D2 (ergocalciferol) is synthesized in plants. Both types must be converted in the liver and kidneys to the active form, 1,25 dihydroxyvitamin D, to be utilized in the body.