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beryllium

(Encyclopedia)beryllium bərĭlˈēəm [key] [from beryl ], metallic chemical element; symbol Be; at. no. 4; at. wt. 9.01218; m.p. about 1,278℃; b.p. 2,970℃ (estimated); sp. gr. 1.85 at 20℃; valence +2. Ber...

spontaneous combustion

(Encyclopedia)spontaneous combustion, phenomenon in which a substance unexpectedly bursts into flame without apparent cause. In ordinary combustion, a substance is deliberately heated to its ignition point to make ...

amino group

(Encyclopedia)amino group, in chemistry, functional group that consists of a nitrogen atom attached by single bonds to hydrogen atoms, alkyl groups, aryl groups, or a combination of these three. An organic compound...

Gothic architecture and art

(Encyclopedia)Gothic architecture and art, structures (largely cathedrals and churches) and works of art first created in France in the 12th cent. that spread throughout Western Europe through the 15th cent., and i...

art conservation and restoration

(Encyclopedia)art conservation and restoration, the preservation of structurally sound works of art, the halting of processes that lead to the damage of works of art, and the repair of already damaged works of art....

W and Z particles

(Encyclopedia)W and Z particles, elementary particles that mediate, or carry, the fundamental force associated with weak interactions. The discovery of the W and Z particles at CERN near Geneva, Switzerland, in the...

magnesium

(Encyclopedia)magnesium măgnēˈzēəm, –zhəm [key], metallic chemical element; symbol Mg; at. no. 12; at. wt. 24.3050; m.p. about 648.8℃; b.p. about 1,090℃; sp. gr. 1.738 at 20℃; valence +2. In 1808, Sir...

drug addiction and drug abuse

(Encyclopedia)drug addiction and drug abuse, chronic or habitual use of any chemical substance to alter states of body or mind for other than medically warranted purposes. Traditional definitions of addiction, with...

crusher

(Encyclopedia)crusher, machine used to reduce materials such as ore, coal, stone, and slag to particle sizes that are convenient for their intended uses. Crushers operate by slowly applying a large force to the mat...

Gramm-Rudman-Hollings Act

(Encyclopedia)Gramm-Rudman-Hollings Act, officially the Balanced Budget and Emergency Deficit Control Act of 1985, U.S. budget deficit reduction measure. The law provided for automatic spending cuts to take effect ...