cysteine: an amino acid containing sulfur that is found in most proteins; oxidizes on exposure to air to form cystine
relation: an abstraction belonging to or characteristic of two entities or parts together
julian calendar: the solar calendar introduced in Rome in 46 b.c. by Julius Caesar and slightly modified by Augustus, establishing the 12-month year of 365 days with each 4th year having 366 days and the months having 31 or 30 days except for February