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silicon

(Encyclopedia)silicon, nonmetallic chemical element; symbol Si; at. no. 14; interval in which at. wt. ranges 28.084–28.086; m.p. 1,410℃; b.p. 2,355℃; sp. gr. 2.33 at 25℃; valence usually +4. Silicon is the ...

Hinshelwood, Sir Cyril Norman

(Encyclopedia)Hinshelwood, Sir Cyril Norman, 1897–1967, British chemist, D.Sc. Oxford, 1924. In 1937 Hinshelwood became a professor at Oxford, where he remained until his retirement in 1964. He shared the 1956 No...

Germiston

(Encyclopedia)Germiston jûrˈmĭstən [key], city, now part and seat of Ekurhuleni metropolitan municipality, Gauteng prov., NE South Africa, on the Witwatersrand. The chief industries are gold mining and processi...

buffer

(Encyclopedia)buffer, solution that can keep its relative acidity or alkalinity constant, i.e., keep its pH constant, despite the addition of strong acids or strong bases. Buffer solutions are frequently solutions ...

oxidases

(Encyclopedia)oxidases, in biochemistry, enzymes that catalyze reactions that directly involve molecular oxygen (see oxidation and reduction). Some utilize flavin coenzymes derived from riboflavin (see vitamin B2)....

oxy group

(Encyclopedia)oxy group ŏkˈsē [key], in chemistry, functional group that consists of an oxygen atom joined by single bonds to two separate alkyl groups or aryl groups. It is the functional group of ethers. ...

emphysema

(Encyclopedia)emphysema ĕmfĭsēˈmə [key], pathological or physiological enlargement or overdistention of the air sacs of the lungs. A major cause of pulmonary insufficiency in chronic cigarette smokers, emphyse...

fainting

(Encyclopedia)fainting or syncope sĭngˈkəpē [key], temporary loss of consciousness caused by an insufficient supply of oxygen to the brain. It can be concurrent with any serious disease or condition, such as he...

nonmetal

(Encyclopedia)nonmetal, chemical element possessing certain properties by which it is distinguished from a metal. In general, this distinction is drawn on the basis that a nonmetal tends to accept electrons and for...

heart-lung machine

(Encyclopedia)heart-lung machine, device that maintains the circulation of the blood and the oxygen content of the body when connected with the arteriovenous system; it is also called the pump oxygenator. The machi...