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hydrogenation

(Encyclopedia)hydrogenation hīdrôjˈənāˌshən, hīˌdrəjənāˈshən [key], chemical reaction of a substance with molecular hydrogen, usually in the presence of a catalyst. A common hydrogenation is the harde...

sonic boom

(Encyclopedia)CE5 Sonic boom wave pattern from a supersonic aircraft and variation in pressure sonic boom, shock wave produced by an object moving through the air at supersonic speed, i.e., faster than the spee...

ziggurat

(Encyclopedia)CE5 Ziggurat ziggurat zĭgˈo͝orăt [key], form of temple common to the Sumerians, Babylonians and Assyrians. The earliest examples date from the end of the 3d millenium b.c., the latest from the...

cysteine

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

clavichord

(Encyclopedia)CE5 Clavichord clavichord klăvˈĭkôrd [key], keyboard musical instrument invented in the Middle Ages. It consists of a small rectangular wooden box, placed upon a table or on legs, containing a...

Chaetognatha

(Encyclopedia)CE5 Anatomy of an arrow worm, Sagitta, representative of the phylum Chaetognatha Chaetognatha kētôgnăthˈə [key], phylum of predominantly pelagic marine animals commonly known as arrowworms. A...

glockenspiel

(Encyclopedia)CE5 Glockenspiel glockenspiel glŏkˈənspēl [key] [Ger.,=bell-play], percussion instrument. The medieval glockenspiel was a sort of miniature carillon (see bell), sometimes played mechanically b...

tympanum

(Encyclopedia)CE5 Tympanum (west pediment, temple of Aphaia at Aegina) tympanum tĭmˈpənəm [key]. In architecture, the triangular space of a pediment, or low-pitched gable, above a portico, door, or window. ...

French horn

(Encyclopedia)CE5 French horn French horn, brass wind musical instrument. Fundamentally a metal tube of narrow conical bore, it is curved into circles because of its great length. The horn ends in a wide flare....

pendentive

(Encyclopedia)CE5 Pendentives pendentive, in architecture, a constructive device permitting the placing of a circular dome over a square room or an elliptical dome over a rectangular room. The pendentives, whic...