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Nguyen Van Thieu
Nguyen Van Thieu , 1924-2001, president of the former Republic of South Vietnam (1967-75). After World War II, he joined the Viet Minh , but then left it to join what became the South Vietnamese National Army (ARVN). He rose rapidly, becoming a division commander. In 1963, he helped lead the coup o...
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Pb
Pb symbol for the element lead .
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red lead
red lead bright red to orange-red powder, also called minium, that is used in the manufacture of storage batteries, lead glass, and red pigments; a paint made with red lead is commonly used to protect iron and steel from rusting. Chemically, red lead is lead tetroxide, Pb 3 O 4 , a water-insoluble ...
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pencil
pencil pointed implement used in writing or drawing to apply graphite or a similar colored solid to any surface, especially paper. From prehistoric times lumps of colored earth or chalk were used as markers. The Egyptians ruled lines with metallic lead, as did medieval monks. The so-called lead pen...
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Organization of African Unity
Organization of African Unity (OAU), former international organization, established 1963 at Addis Ababa, Ethiopia, by 37 independent African nations to promote unity and development; defend the sovereignty and territorial integrity of members; eradicate all forms of colonialism; promote internation...
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Mendip Hills
Mendip Hills range of hills, c.25 mi (40 km) long, across N Somerset, SW England, extending SE from the vicinity of Hutton to the Frome valley. Primarily limestone, the hills have numerous caves (Wookey Hole, Cheddar Caves), some of which show signs of prehistoric occupation. In the hills are ruins...
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lead
lead metallic chemical element; symbol Pb [Lat. plumbum ]; at. no. 82; at. wt. 207.2; m.p. 327.502°C; b.p. about 1,740°C; sp. gr. 11.35 at 20°C; valence +2 or +4. One of the oldest metals used by humanity, lead was known to the ancient Egyptians and Babylonians. The Romans used it for ...
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Caspian Sea
Caspian Sea , Lat. Mare Caspium or Mare Hyrcanium, salt lake, c.144,000 sq mi (373,000 sq km), between Europe and Asia; the largest lake in the world. It is bordered on the northeast by Kazakhstan, on the southeast by Turkmenistan, on the south by Iran, on the southwest by Azerbaijan, and on the...
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tetraethyl lead
tetraethyl lead , (C 2 H 5 ) 4 Pb, viscous, colorless, poisonous liquid. It is an organometallic compound prepared by reacting ethyl chloride with a sodium-lead alloy. When added to gasoline, it improves the combustion characteristics (see octane number ). When tetraethyl lead burns in an engine, l...
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lead poisoning
lead poisoning or plumbism , intoxication of the system by organic compounds containing lead . These enter the body by respiration (of dust, fumes, or sprays) or by ingestion of food or other substances that contain lead. Lead poisoning, formerly a leading occupational hazard in industrialized ...
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