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tin

(Encyclopedia)tin, metallic chemical element; symbol Sn [Lat. stannum]; at. no. 50; at. wt. 118.710; m.p. 231.9681℃; b.p. 2,270℃; sp. gr. 5.75 (gray), 7.3 (white); valence +2 or +4. Tin exhibits allotropy; abov...

Kroto, Harry

(Encyclopedia)Kroto, Harry (Sir Harold Walter Kroto), 1939–2016, British chemist, b. Harold Walter Krotoschiner, Ph.D. Univ. of Sheffield, 1964. Kroto was the son of German parents who fled Nazi rule to England. ...

Lucknow

(Encyclopedia)Lucknow or Lakhnau both: lŭkˈnou [key], city (1991 pop. 1,669,204), capital of Uttar Pradesh state, N central India, on the Gomati River. An educational and cultural center, it has varied industries...

naked mole rat

(Encyclopedia)naked mole rat, name applied to a species (Heterocephalus glaber) of small rodents found in E Africa, whose members—the only hairless rodents—live entirely in underground communities of 80 or more...

Hatteras, Cape

(Encyclopedia)Hatteras, Cape hătˈərəs [key], promontory on Hatteras Island, a low, sandy, barrier bar between the Atlantic Ocean and Pamlico Sound, E N.C. Called the Graveyard of the Atlantic, the cape experien...

Hausa

(Encyclopedia)Hausa or Haussa both: houˈsə, –sä [key], black African ethnic group, numbering about 23 million, chiefly in N Nigeria and S Niger. The Hausa are almost exclusively Muslim and practice agriculture...

antidiuretic hormone

(Encyclopedia)antidiuretic hormone ănˌtēdīyo͞orĕtˈĭk [key], polypeptide hormone secreted by the posterior pituitary gland. Its principal action is to regulate the amount of water excreted by the kidneys. An...

hernia

(Encyclopedia)hernia, protrusion of an internal organ or part of an organ through the wall of a body cavity. The hernia is enclosed by a sac formed by the lining of the cavity. It results from a weakness or rupture...

gypsum

(Encyclopedia)gypsum jĭpˈsəm [key], mineral composed of calcium sulfate (calcium, sulfur, and oxygen) with two molecules of water, CaSO4·2H2O. It is the most common sulfate mineral, occurring in many places in ...

Guarini, Guarino

(Encyclopedia)Guarini, Guarino gwärēˈnō gwärēˈnē [key], 1624–83, Italian architect, mathematician, and writer. He was one of the first to analyze with perceptivity the structure of medieval architecture, ...