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cadmium

(Encyclopedia)cadmium kădˈmēəm [key] [from cadmia, Lat. for calamine, with which cadmium is found associated], metallic chemical element; symbol Cd; at. no. 48; at. wt. 112.411; m.p. 321℃; b.p. 765℃; sp. gr...

aircraft carrier

(Encyclopedia)aircraft carrier, ship designed to carry aircraft and to permit takeoff and landing of planes. The carrier's distinctive features are a upper deck (flight deck) that is flat and sometimes sloped to fu...

transmutation of elements

(Encyclopedia)transmutation of elements, conversion of one chemical element into another. The expression has both historical and contemporary significance. The transmutation of certain metals into gold by means of ...

samarium

(Encyclopedia)samarium səmârˈēəm [key], metallic chemical element; symbol Sm; at. no. 62; at. wt. 150.36; m.p. 1,072℃; b.p. 1,791℃; sp. gr. 7.54 at 20℃; valence +2 or +3. Samarium is a lustrous silver-wh...

Hoover, Herbert Clark

(Encyclopedia)Hoover, Herbert Clark, 1874–1964, 31st President of the United States (1929–33), b. West Branch, Iowa. Except for major speeches before the Republican conventions and a 1938 European tour, Hoove...

League of Nations

(Encyclopedia)League of Nations, former international organization, established by the peace treaties that ended World War I. Like its successor, the United Nations, its purpose was the promotion of international p...

land use

(Encyclopedia)land use, exploitation of land for agricultural, industrial, residential, recreational, or other purposes. Because the United States historically has a laissez-faire attitude toward land use, the land...

thorium

(Encyclopedia)thorium thôrˈēəm [key] [from Thor], radioactive chemical element; symbol Th; at. no. 90; mass number of most stable isotope 232; m.p. about 1,750℃; b.p. about 4,790℃; sp. gr. 11.7 at 20℃; va...

Obama, Barack

(Encyclopedia)Obama, Barack (Barack Hussein Obama 2d), bəräkˈ ho͞osānˈ ōbäˈmə [key], 1961–, 44th president of the United States (2009–17), b. Honolulu, grad. Columbia (B.A. 1983), Harvard Law School ...

Bush, George Walker

(Encyclopedia)Bush, George Walker, 1946–, 43d President of the United States (2001–9), b. New Haven, Conn. The eldest son of President George H. W. Bush, he was was raised in Texas and, like his father, attende...