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nuclear reactor

(Encyclopedia)CE5 Power reactor system nuclear reactor, device for producing controlled release of nuclear energy. Reactors can be used for research or for power production. A research reactor is designed to pr...

gamma radiation

(Encyclopedia)gamma radiation, high-energy photons emitted as one of the three types of radiation resulting from natural radioactivity. It is the most energetic form of electromagnetic radiation, with a very short ...

micromechanics

(Encyclopedia)micromechanics, the combination of minuscule electrical and mechanical components in a single device less than 1 mm across, such as a valve or a motor. Although micromechanical production processes an...

King, William Lyon Mackenzie

(Encyclopedia)King, William Lyon Mackenzie, 1874–1950, Canadian political leader, b. Kitchener, Ont.; grandson of William Lyon Mackenzie. An expert on labor questions, he served in Wilfrid Laurier's Liberal admin...

rare-earth metals

(Encyclopedia)rare-earth metals, in chemistry, group of metals including those of the lanthanide series and actinide series and usually yttrium, sometimes scandium and thorium, and rarely zirconium. Promethium, whi...

Eastwood, Clint

(Encyclopedia)Eastwood, Clint (Clinton Eastwood, Jr.), 1930–, American actor and director, b. San Francisco. Eastwood, who began his acting career in 1955, came to public attention in the TV Western Rawhide and i...

White House

(Encyclopedia)White House, official name of the executive mansion of the President of the United States. It is on the south side of Pennsylvania Ave., Washington, D.C., facing Lafayette Square. The building, constr...

Black Panthers

(Encyclopedia)Black Panthers, U.S. African-American militant party, founded (1966) in Oakland, Calif., by Huey P. Newton and Bobby Seale. Originally aimed at armed self-defense against the local police, the party g...

chemistry

(Encyclopedia)chemistry, branch of science concerned with the properties, composition, and structure of substances and the changes they undergo when they combine or react under specified conditions. Organic chemi...

carbon

(Encyclopedia)CE5 The three solid forms of pure carbon: In the diamond crystal each carbon atom is surrounded symmetrically by four other carbons (at each of the four corners of a tetrahedron). In the graphite c...