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pyrite

(Encyclopedia)pyrite pīrīˈtēz, pə–, pīˈrīts [key], pale brass-yellow mineral, the bisulfide of iron, FeS2. It occurs most commonly in crystals (belonging to the isometric system and usually in the form of...

adsorption

(Encyclopedia)adsorption, adhesion of the molecules of liquids, gases, and dissolved substances to the surfaces of solids, as opposed to absorption, in which the molecules actually enter the absorbing medium (see a...

Adirondack Mountains

(Encyclopedia)Adirondack Mountains ădˌərŏnˈdăk [key], mountain mass, NE N.Y., between the St. Lawrence valley in the north and the Mohawk valley in the south; rising to 5,344 ft (1,629 m) at Mt. Marcy, the hi...

Ramakrishnan, Venkatraman

(Encyclopedia)Ramakrishnan, Venkatraman, 1952–, American molecular biologist, b. India, Ph.D. Ohio Univ., 1976. He was a researcher at Oak Ridge National Laboratory (1982–83) and at Brookhaven National Laborato...

sprue

(Encyclopedia)sprue, chronic disorder of the small intestine caused by impaired absorption of fat and other nutrients. Two forms of the disease exist. Tropical sprue occurs in central and northern South America, As...

silica

(Encyclopedia)silica or silicon dioxide, chemical compound, SiO2. It is insoluble in water, slightly soluble in alkalies, and soluble in dilute hydrofluoric acid. Pure silica is colorless to white. It occurs in sev...

rhodium

(Encyclopedia)rhodium rōˈdēəm [key], metallic chemical element; symbol Rh; at. no. 45; at. wt. 102.90550; m.p. about 1,966℃; b.p. 3,727±100℃; sp. gr. 12.41 at 20℃; valence +2, +3, +4, +5, or +6. Rhodium ...

food preservation

(Encyclopedia)food preservation, methods of preparing food so that it can be stored for future use. Because most foods remain edible for only a brief period of time, people since the earliest ages have experimented...

fluorine

(Encyclopedia)fluorine flo͞oˈərēn, –rĭn [key], gaseous chemical element; symbol F; at. no. 9; at. wt. 18.9984; m.p. −219.6℃; b.p. −188.14℃; density 1.696 grams per liter at STP; valence −1. Fluorin...

paper

(Encyclopedia)paper, thin, flat sheet or tissue made usually from plant fiber but also from rags and other fibrous materials. It is used principally for printing and writing on but has many other applications. The ...