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acne

(Encyclopedia)acne, common inflammatory disease of the hair follicles and sebaceous glands characterized by blackheads, whiteheads, pustules, nodules and, in the more severe forms, by cysts and scarring. The lesion...

carbon monoxide

(Encyclopedia)carbon monoxide, chemical compound, CO, a colorless, odorless, tasteless, extremely poisonous gas that is less dense than air under ordinary conditions. It is very slightly soluble in water and burns ...

Arctic, the

(Encyclopedia)CE5 Arctic, the northernmost area of the earth, centered on the North Pole. The arctic regions are not coextensive with the area enclosed by the Arctic Circle (lat. 66°30′N) but are usually defi...

wind chill

(Encyclopedia)wind chill, the cooling effect of wind and temperature combined, expressed in terms of the effect produced by a lower, windless temperature, also called wind chill factor, wind chill temperature, wind...

white dwarf

(Encyclopedia)white dwarf, in astronomy, a type of star that is abnormally faint for its white-hot temperature (see mass-luminosity relation). Typically, a white dwarf star has the mass of the sun and the radius of...

chromosphere

(Encyclopedia)chromosphere krōˈməsfērˌ [key] [Gr.,=color sphere], layer of rarefied, transparent gases in the solar atmosphere; it measures 6,000 mi (9,700 km) in thickness and lies between the photosphere (th...

clay

(Encyclopedia)clay, common name for a number of fine-grained, earthy materials that become plastic when wet. Chemically, clays are hydrous aluminum silicates, ordinarily containing impurities, e.g., potassium, sodi...

bivalve

(Encyclopedia)CE5 Internal anatomy of a clam, Anodonta, representative mollusk of the class Pelecypoda (the bivalves) bivalve, aquatic mollusk of the class Pelecypoda (“hatchet-foot”) or Bivalvia, with a la...

Arctic Ocean

(Encyclopedia)Arctic Ocean, the smallest ocean, c.5,400,000 sq mi (13,986,000 sq km), located entirely within the Arctic Circle and occupying the region around the North Pole. The Arctic basin was almost wholly u...

liposome

(Encyclopedia)liposome līˈpəsōmˌ, lĭpˈə– [key], microscopic, fluid-filled pouch whose walls are made of layers of phospholipids identical to the phospholipids that make up cell membranes. Liposomes are us...