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hydrogen bomb

(Encyclopedia)hydrogen bomb or H-bomb, weapon deriving a large portion of its energy from the nuclear fusion of hydrogen isotopes. In an atomic bomb, uranium or plutonium is split into lighter elements that togethe...

oxygen

(Encyclopedia)oxygen, gaseous chemical element; symbol O; at. no. 8; interval in which at. wt. ranges 15.99903–15.99977; m.p. −218.4℃; b.p. −182.962℃; density 1.429 grams per liter at STP; valence −2. T...

decay of organic matter

(Encyclopedia)decay of organic matter or putrefaction, process whereby heterotrophic organisms, including some bacteria, fungi, saprophytic plants, and lower animals, utilize the remains of once-living tissue as a ...

Cole, Thomas

(Encyclopedia)Cole, Thomas, 1801–48, American landscape painter, b. England. He arrived in the United States in 1818 and moved to Ohio, where he was impressed by the beauty of the countryside. In 1825 he went to ...

Gray, Asa

(Encyclopedia)Gray, Asa, 1810–88, one of America's leading botanists and taxonomists, b. Oneida co., N.Y. As professor of natural history at Harvard from 1842, he was the teacher of many eminent botanists. Throug...

Nervi, Pier Luigi

(Encyclopedia)Nervi, Pier Luigi pyĕr lwo͞oēˈjē nĕrˈvē [key], 1891–1979, Italian architectural engineer. Nervi is considered one of the foremost European architectural designers of the 20th cent. His first...

Archaebacteria

(Encyclopedia)Archaebacteria ärˌkēbăktĭrˈēə [key], diverse group of bacteria (prokaryotes), sometimes called the archaea and considered a major group unto themselves. Archaebacteria are contrasted with the ...

Mitchell, Joan

(Encyclopedia)Mitchell, Joan, 1926–92, American abstract painter, b. Chicago, studied Smith College, Art Institute of Chicago (B.F.A., 1947; M.F.A., 1950). A vibrant colorist, she was one of the finest painters o...

mass spectrograph

(Encyclopedia)mass spectrograph, device used to separate electrically charged particles according to their masses; a form of the instrument known as a mass spectrometer is often used to measure the masses of isotop...

archetype

(Encyclopedia)archetype ärˈkĭtīpˌ [key] [Gr. arch=first, typos=mold], term whose earlier meaning, “original model,” or “prototype,” has been enlarged by C. G. Jung and by several contemporary literary ...