7-dehydrocholesterol (sometimes known as provitamin D3) is a chemical that, in the presence of ultraviolet light, is converted by the body to previtamin D3 which is then isomerized into Vitamin D3.
... distress signal[?] "CQD" is established only to be replaced two years later by "SOS."
February 7 - A fire in Baltimore, Maryland destroys over 1,500 buildings in 30 ...