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Pine Bluff

(Encyclopedia)Pine Bluff, city (1990 pop. 57,140), seat of Jefferson co., S central Ark., on the Arkansas River; inc. 1839. It is a port and trade center for an agricultural area and has industries producing metal,...

Stargard Szczeciński

(Encyclopedia)Stargard Szczeciński ĭn pôˈmərn [key], town (1994 est. pop. 72,000), Zachodniopomorskie prov., NW Poland. It is a rail junction and has metalworking and chemical industries. Chartered in the 13th...

Siegbahn, Kai Manne Borje

(Encyclopedia)Siegbahn, Kai Manne Borje, 1918–2007, Swedish physicist, son of Karl Siegbahn. He earned his doctorate at the Univ. of Stockholm in 1944 and later taught at the Royal Institute of Technology, Stockh...

alkene

(Encyclopedia)CE5 Alkenes alkene ălˈkēn [key], any of a group of aliphatic hydrocarbons whose molecules contain one or more carbon-carbon double bonds (see chemical bond). Alkenes with only one double bond h...

fuel cell

(Encyclopedia)fuel cell, electric cell in which the chemical energy from the oxidation of a gas fuel is converted directly to electrical energy in a continuous process (see oxidation and reduction). The efficiency ...

oxide

(Encyclopedia)oxide, chemical compound containing oxygen and one other chemical element. Oxides are widely and abundantly distributed in nature. Water is the oxide of hydrogen. Silicon dioxide is the major componen...

photochemistry

(Encyclopedia)photochemistry, study of chemical processes that are accompanied by or catalyzed by the emission or absorption of visible light or ultraviolet radiation. A molecule in its ground (unexcited) state can...

polonium

(Encyclopedia)polonium pəlōˈnēəm [key], radioactive chemical element; symbol Po; at. no. 84; mass no. of most stable isotope 209; m.p. 254℃; b.p. 962℃; sp. gr. about 9.4; valence +2 or +4. Polonium is an e...

urinalysis

(Encyclopedia)urinalysis yo͝orˌənălˈĭsĭs [key], clinical examination of urine for the purpose of medical diagnosis. Urine is initially examined for such characteristics as color, odor, and specific gravity. ...

ruthenium

(Encyclopedia)ruthenium ro͞othēˈnēəm [key], metallic chemical element; symbol Ru; at. no. 44; at. wt. 101.07; m.p. about 2,310℃; b.p. about 3,900℃; sp. gr. 12.41 at 20℃; valence commonly +2, +3, +4, +6, ...