activity or concentration gradient is employed
41coal mining — Coal was very important in the economic development of Britain. It was used as fuel in the factories built during the Industrial Revolution and continued to be important until the 1980s. The main coalfields are in north east England, the north… …
42petroleum — petroleous, adj. /peuh troh lee euhm/, n. an oily, thick, flammable, usually dark colored liquid that is a form of bitumen or a mixture of various hydrocarbons, occurring naturally in various parts of the world and commonly obtained by drilling:… …
43Physical Sciences — ▪ 2009 Introduction Scientists discovered a new family of superconducting materials and obtained unique images of individual hydrogen atoms and of a multiple exoplanet system. Europe completed the Large Hadron Collider, and China and India took… …
44Thermodynamics — Annotated color version of the original 1824 Carnot heat engine showing the hot body (boiler), working body (system, steam), and cold body (water), the letters labeled according to the stopping points in Carnot cycle …
45Oldham — For other uses, see Oldham (disambiguation). For the larger local government district, see Metropolitan Borough of Oldham. Coordinates: 53°32′40″N 2°07′01″W / …
46Venezuela — Venezuelan, adj., n. /ven euh zway leuh, zwee /; Sp. /be ne swe lah/, n. a republic in N South America. 22,396,407; 352,143 sq. mi. (912,050 sq. km). Cap.: Caracas. * * * Venezuela Introduction Venezuela Background: Venezuela was one of the three …
47Confederate Gulch and Diamond City — Confederate Gulch is a steeply incised valley on the west facing slopes of the Big Belt Mountains. Its small stream drains westward into Canyon Ferry Lake, on the upper Missouri River Valley near present day Townsend, Montana. In 1864 Confederate …
48Beaker culture — The Bell Beaker culture (sometimes shortened to Beaker culture, Beaker people, or Beaker folk; de. Glockenbecherkultur), ca. 2800 ndash; 1900 BC, is the term for a widely scattered cultural phenomenon of prehistoric western Europe starting in the …
49Geographic information system — GIS redirects here. For other uses, see GIS (disambiguation). A geographic information system, geographical information science, or geospatial information studies is a system designed to capture, store, manipulate, analyze, manage, and present… …
50Sudan, The — officially Republic of the Sudan Country, North Africa. Area: 966,757 sq mi (2,503,890 sq km). Population (2002 est.): 37,090,000. Capital: Khartoum. Muslim Arab ethnic groups live in the northern and central two thirds of the country, while… …
