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leaching

(Encyclopedia)leaching, method of extraction in which a solvent is passed through a mixture to remove some desired substance from it. A simple example is the passage of boiling water through ground coffee to dissol...

photoengraving

(Encyclopedia)photoengraving, photomechanical process in the graphic arts, used principally for reproducing illustrations. The subject is photographed, and the image is recorded on a sensitized metal plate, which i...

Szent-Gyorgyi, Albert von

(Encyclopedia)Szent-Gyorgyi, Albert von älˈbĕrt fən sĕntˌ-dyörˈdyĭ [key], 1893–1986, American biochemist, b. Hungary, M.D. Univ. of Budapest, 1917; Ph.D. Cambridge, 1927. After teaching at the universiti...

tautomer

(Encyclopedia)tautomer tôˈtəmər [key], one of two or more structural isomers that exist in equilibrium and are readily converted from one isomeric form to another. Of the various types of tautomerism that are p...

Reichstein, Tadeus

(Encyclopedia)Reichstein, Tadeus tädĕˈo͞osh rīkhˈshtīn [key], 1897–1996, Swiss organic chemist, b. Vlotslavsk, Russia (now Włocławek, Poland), educated at the technical school in Zürich, where he also t...

Skou, Jens Christian

(Encyclopedia)Skou, Jens Christian, 1918–2018, Danish chemist, M.D. Univ. of Copenhagen, 1944, Ph.D. Univ. of Aarhus, 1954. Skou was on the faculty at the Univ. of Aarhus, Denmark, from 1947 until he retired in 1...

Abidjan

(Encyclopedia)Abidjan ăbĭjänˈ [key], city (2021 est. pop. 27,263,180 ), former capital of Côte d'Ivoire, a port on the Ébrié Lagoon (an arm of the Gulf of Guinea). Abidjan is Cô...

Nelson, Willie

(Encyclopedia)Nelson, Willie, 1933–, American country singer, guitarist, and songwriter, b. Abbott, Tex. Nelson began playing professionally at 10 and joined a western swing band as a teenager. In the 1960s he mo...

levee

(Encyclopedia)levee lĕvˈē [key] [Fr.,=raised], embankment built along a river to prevent flooding by high water. Levees are the oldest and the most extensively used method of flood control. They are constructed ...

Roraima

(Encyclopedia)Roraima ro͝orīˈmə [key], state (1996 pop. 247,724), 88,843 sq mi (230,103 sq km), NW Brazil, on the border of Venezuela and Guyana. Boa Vista is the capital. Located almost entirely in the Guiana ...