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thyroxine

(Encyclopedia)thyroxine thīrŏkˈsēn [key], substance secreted by the thyroid gland. The hormone thyroxine forms by combining the amino acid tyrosine with iodine. Complexed to a protein, it is stored in the folli...

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...

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...

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...

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 ...

pollution allowance

(Encyclopedia)pollution allowance or emission rights, government-issued permit to emit a certain amount of a pollutant. The holder of the permit may use it to pollute legally, may trade permits, or may sell the per...

pomegranate

(Encyclopedia)pomegranate pŏmˈgrănĭt, pŏmˈə– [key], handsome deciduous and somewhat thorny large shrub or small tree (Punica granatum) belonging to the family Punicaceae, native to semitropical Asia and na...

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...

lithography

(Encyclopedia)lithography lĭthŏgˈrəfē [key], type of planographic or surface printing. It is distinguished from letterpress (relief) printing and from intaglio printing (in which the design is cut or etched in...