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Dehn, Adolf Arthur

(Encyclopedia)Dehn, Adolf Arthur dān [key], 1895–1968, American painter and illustrator, b. Waterville, Minn. During the 1920s, Dehn became known as a forceful satiric illustrator. Later he concentrated primaril...

lead acetate

(Encyclopedia)lead acetate, chemical compound, a white crystalline substance with a sweetish taste. Like other lead compounds, it is very poisonous. Lead acetate is soluble in water and glycerin. With water it form...

perfluoroalkyl and polyfluoroalkyl substances

(Encyclopedia)perfluoroalkyl and polyfluoroalkyl substances (PFAS), a group of several thousand synthetic organic chemical compounds made up of a chain of carbon atoms bonded to fluorine atoms. PFAS, which resist w...

backswimmer

(Encyclopedia)backswimmer, common name for water bugs of the cosmopolitan family Notonectidae, so named because they swim upside down, usually near the surface of the water. They have oval bodies and long, oarlike ...

Kara Kum

(Encyclopedia)Kara Kum kärˌə ko͝omˈ [key], two deserts, one in Kazakhstan and one in Turkmenistan. The Caspian Kara Kum or Garagum, the larger desert (c.115,000 sq mi/297,900 sq km), is W of the Amu Darya Rive...

surface tension

(Encyclopedia)surface tension, tendency of liquids to reduce their exposed surface to the smallest possible area. A drop of water, for example, tends to assume the shape of a sphere. The phenomenon is attributed to...

photosynthesis

(Encyclopedia)photosynthesis fōˌtōsĭnˈthəsĭs [key], process in which green plants, algae, and cyanobacteria utilize the energy of sunlight to manufacture carbohydrates from carbon dioxide and water in the pr...

Pacific Ocean

(Encyclopedia)CE5 Pacific Ocean, largest and deepest ocean, c.70,000,000 sq mi (181,300,000 sq km), occupying about one third of the earth's surface; named by the explorer Ferdinand Magellan; the southern part i...

heating

(Encyclopedia)CE5 Typical warm-air heating system heating, means of making a building comfortably warm relative to a colder outside temperature. Old, primitive methods of heating a building or a room within it ...

sponge

(Encyclopedia)sponge, common name for members of the aquatic animal phylum Porifera, and for the dried, processed skeletons of certain species used to hold water. Over 4,500 living species are known; they are found...