concentrate;+make+dense
41Nigeria — Nigerian, adj., n. /nuy jear ee euh/, n. a republic in W Africa: member of the Commonwealth of Nations; formerly a British colony and protectorate. 107,129,469; 356,669 sq. mi. (923,773 sq. km). Cap.: Abuja. Official name, Federal Republic of… …
42nuclear reactor — Physics. reactor (def. 4). Also called nuclear pile. [1940 45] * * * Device that can initiate and control a self sustaining series of nuclear fission reactions. Neutrons released in one fission reaction may strike other heavy nuclei, causing them …
43Manhattan Project — This article is about the atomic bomb project. For other uses, see Manhattan Project (disambiguation). Manhattan District The Manhattan Project created the first nuclear bombs. The Trinity test …
44Astronomy — (from the Greek words astron (ἄστρον), star , and nomos (νόμος), law ) is the scientific study of celestial objects (such as stars, planets, comets, and galaxies) and phenomena that originate outside the Earth s atmosphere (such as the cosmic… …
45Social behaviour in animals — Introduction actions of animals living in communities. Such behaviour may include the feeding of the young, the building of shelters, or the guarding of territory. General characteristics Social behaviour (Social behaviour in animals) …
46Siege of Sevastopol (1941–1942) — For the Crimean War battle, see Siege of Sevastopol (1854–1855). Siege of Sevastopol (1941–1942) Part of the Eastern Front of World War II …
47river — river1 riverless, adj. riverlike, adj. /riv euhr/, n. 1. a natural stream of water of fairly large size flowing in a definite course or channel or series of diverging and converging channels. 2. a similar stream of something other than water: a… …
48tactics — /tak tiks/, n. 1. (usually used with a sing. v.) the art or science of disposing military or naval forces for battle and maneuvering them in battle. 2. (used with a pl. v.) the maneuvers themselves. 3. (used with a sing. v.) any mode of procedure …
49Uranium — (pronEng|jʊˈreɪniəm) is a silvery gray metallic chemical element in the actinide series of the periodic table that has the symbol U and atomic number 92. It has 92 protons and 92 electrons, 6 of them valence electrons. It can have between 141 and …
50United Kingdom — a kingdom in NW Europe, consisting of Great Britain and Northern Ireland: formerly comprising Great Britain and Ireland 1801 1922. 58,610,182; 94,242 sq. mi. (244,100 sq. km). Cap.: London. Abbr.: U.K. Official name, United Kingdom of Great… …
