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MacArthur, Douglas

(Encyclopedia)MacArthur, Douglas, 1880–1964, American general, b. Little Rock, Ark.; son of Arthur MacArthur. At the beginning (1950) of the Korean War he was appointed commander of UN military forces in South ...

designer drug

(Encyclopedia)designer drug, chemical substance synthesized in a laboratory that is intended to have effects similar to those of a drug that is a controlled substance, such as methamphetamine, marijuana, LSD, or an...

molybdenum

(Encyclopedia)molybdenum məlĭbˈdənəm [key] [Gr.,=leadlike], metallic chemical element; symbol Mo; at. no. 42; at. wt. 95.96; m.p. about 2,617℃; b.p. about 4,612℃; sp. gr. 10.22 at 20℃; valence +2, +3, +4...

atomic clock

(Encyclopedia)atomic clock, electric or electronic timekeeping device that is controlled by atomic or molecular oscillations. A timekeeping device must contain or be connected to some apparatus that oscillates at a...

arsenic

(Encyclopedia)arsenic ärˈsənĭk [key], a semimetallic chemical element; symbol As; at. no. 33; at. wt. 74.92160; m.p. 817℃ (at 28 atmospheres pressure); sublimation point 613℃; sp. gr. (stable form) 5.73; va...

antimony

(Encyclopedia)antimony ănˈtĭmōˌnē [key] [Lat. antimoneum], semimetallic chemical element; symbol Sb [Lat. stibium,=a mark]; at. no. 51; at. wt. 121.760; m.p. 630.74℃; b.p. 1,750℃; sp. gr. (metallic form) ...

cosmic rays

(Encyclopedia)cosmic rays, charged particles moving at nearly the speed of light reaching the earth from outer space. Primary cosmic rays consist mostly of protons (nuclei of hydrogen atoms), some alpha particles (...

chlorate

(Encyclopedia)chlorate pərklōrˈāt, –klôrˈ– [key], salts of chloric acid, HClO3, and perchloric acid, HClO4, respectively. Perchlorates are safer to handle than chlorates; they are more stable when expos...

Neptune, in astronomy

(Encyclopedia)Neptune, in astronomy, 8th planet from the sun at a mean distance of about 2.8 billion mi (4.5 billion km) with an orbit lying between those of Uranus and the dwarf planet Pluto; its period of revolut...

superconductivity

(Encyclopedia)superconductivity, abnormally high electrical conductivity of certain substances. The phenomenon was discovered in 1911 by Heike Kamerlingh Onnes, who found that the resistance of mercury dropped sudd...