Steroid hor­mones related to the male sex hor­mone testosterone. They promote the development of masculine char­acteristics and increase muscle growth. Anabolic steroids have been used medically for various conditions but are also used illegally by sports­men and women and by body­builders. They have a number of deleterious side effects and are a con­trolled drug in

amperometric titration : A method of determining the chemical composition of a solution by measur­ing the current passing through a cell containing the solution; the po­tential is held constant during the titration for both the indicator and reference electrodes, with changes in the current being measured. The cur­rent flowing through the cell is meas­ured as

ammonia clock A form of atomic clock in which the frequency of a quartz oscillator is controlled by the vibrations of excited ammonia molecules. The ammonia molecule (NH3) consists of a pyramid with a ni­trogen atom at the apex and one hy­drogen atom at each corner of the triangular base. When the molecule is excited,