Actin: The protein from which microfilaments are composed; forms the contractile filaments of sarcomeres in muscle cells.
Actinide: Elements 89-102 are called actinides. Electrons added during the Aufbau construction of actinide atoms go into the 5f subshell. Actinides are unstable and undergo radioactive decay. The most . . . View Full Definition
Actinium (Ac): Atomic number: 89, Atomic mass: 227 g.mol -1, Electronegativity: 1.1, Density: 10.07 g.cm-3 at 20°C, Melting point: 1050 °C, Boiling point: 3250 °C, Vanderwaals radius: unknown, Ionic radius . . . View Full Definition
Acting Out: This is the process of expressing unconscious emotional conflicts or feelings via actions rather than words. The person is not consciously aware of the meaning or etiology of such acts. Acti . . . View Full Definition
Prolactin: A hormone produced by the anterior pituitary; secreted at the end of pregnancy when it activates milk production by the mammary glands.
Protactinium (Pa): Atomic number: 91, Atomic mass: 231.0359 g.mol -1, Electronegativity: 1.5, Density: 15.37 g.cm-3 at 20°C, Melting point: 1600 °C, Boiling point: unknown, Vanderwaals radius: unknown, Ionic r . . . View Full Definition
Hyperprolactinaemia: An abnormally high level of prolactin in the blood which can occur in both men and women. Typical and some atypical antipsychotics can increase serum levels which can result in menstrual and . . . View Full Definition
Contracting-Band Brake: A brake in which a band is tightened around a rotation drum.
Actinometer: Early type of exposure calculator.
Scleractinia: Order of coelenterates, usually producing calcareous skeletons with hexameral symmetry