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astatine

(Encyclopedia)astatine ăsˈtətēn, –tĭn [key] [Gr.,=unstable], semimetallic radioactive chemical element; symbol At; at. no. 85; at. wt. of most stable isotope 210; m.p. 302℃ (estimated); b.p. 337℃ (estima...

Ashkin, Arthur

(Encyclopedia)Ashkin, Arthur, 1922–2020, American physicist, b. Brooklyn, N.Y., Ph.D. Cornell, 1952. Ashkin worked for four decades at Bell Laboratories, retiring in 1992. Ashkin researched microwaves, nonlinear ...

asparagine

(Encyclopedia)CE5 asparagine əspârˈəjēn [key], organic compound, one of the 20 amino acids commonly found in animal proteins. Only the l-stereoisomer participates in the biosynthesis of mammalian proteins. ...

phenol

(Encyclopedia)phenol fēˈnōl [key], C6H5OH, a colorless, crystalline solid that melts at about 41℃, boils at 182℃, and is soluble in ethanol and ether and somewhat soluble in water. An aromatic alcohol, it ex...

air mass

(Encyclopedia)air mass, large body of air within the earth's atmosphere in which temperature and humidity, although varying at different heights, remain similar throughout the body at any one height. Air masses for...

sweetener, artificial

(Encyclopedia)sweetener, artificial, substance used as a low-calorie sugar substitute. Saccharin, cyclamates, and aspartame have been the most commonly used artificial sweeteners. Saccharin, a coal-tar derivative t...

refining

(Encyclopedia)refining, any of various processes for separating impurities from crude or semifinished materials. It includes the finer processes of metallurgy, the fractional distillation of petroleum into its comm...

tea

(Encyclopedia)tea, tree or bush, its leaves, and the beverage made from these leaves. The plant (Camellia sinensis, Thea sinensis, or C. thea) is an evergreen related to the camellia and indigenous to Assam (India)...

zirconium

(Encyclopedia)zirconium zərkōˈnēəm [key], metallic chemical element; symbol Zr; at. no. 40; at. wt. 91.224; m.p. about 1,852℃; b.p. 4,377℃; sp. gr. 6.5 at 20℃; valence +2, +3, or +4. Zirconium is a very ...

actinide series

(Encyclopedia)actinide series, a series of radioactive metallic elements in Group 3 of the periodic table. Members of the series are often called actinides, although actinium (at. no. 89) is not always considered a...