Columbia Encyclopedia

(Encyclopedia) polyolefins pŏlˌēōlˈəfən [key], group of plastics that are polymers of various alkenes, or olefins. The most important are polyethylene and polypropylene. ...

(Encyclopedia) elevation, vertical distance from a datum plane, usually mean sea level to a point above the earth. Often used synonymously with altitude, elevation is the height on the earth's surface and altitude, ...

(Encyclopedia) epoxy resins, group of synthetic resins used to make plastics and adhesives. These materials are noted for their versatility, but their relatively high cost has limited their use. High resistance to c...

(Encyclopedia) Gunsan or Kunsan go͝onˈsänˈ [key], Jap. Gunzan, city, North Jeolla (Cholla) prov., SW Sou...

(Encyclopedia) New Bern, city (1990 pop. 17,363), seat of Craven co., E N.C., a port and trading center at the junction of the Neuse and Trent rivers; inc. 1723. There is lumbering and food processing, and textiles ...

(Encyclopedia) Northampton nôrthˌhămpˈtən, nôrˌthămpˈtən [key], city (1990 pop. 29,289), seat of Hampshire co., W Mass., on the Connecticut River; inc. as a town 1656, as a city 1883. Brushes, wire, optica...

(Encyclopedia) melamine mĕlˈəmēnˌ [key], common name for 2,4,6-triamino-1,3,5-triazine. Melamine is a trimer (see polymer) of cyanamide, H2NC≡N, and is synthesized from calcium carbide. It condenses with form...

(Encyclopedia) castor oil, yellowish oil obtained from the seed of the castor bean. The oil content of the seeds varies from about 20% to 50%. After the hulls are removed the seeds are cold-pressed. Medicinal castor...

(Encyclopedia) Youngstown, city (1990 pop. 95,732), seat of Mahoning co., NE Ohio, near the Pa. line; founded 1797, inc. 1849. It was formerly a major U.S. iron and steel center. In the 1970s many of the steel mills...

(Encyclopedia) Roanoke rōˈənōk [key], city (1990 pop. 96,397), independent and in no co., SW Va., on the Roanoke River; settled c.1740, inc. 1882, as a city, 1884. It is situated between the Blue Ridge and Alleg...