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pearl, gem

(Encyclopedia)pearl, hard, rounded secretion formed inside the shell of certain mollusks, used as a gem. It is secreted by the epithelial cells of the mantle, a curtain of tissue between the shell and body mass, an...

methyl

(Encyclopedia)methyl mĕthˈəl [key], CH3, organic free radical or alkyl group derived from methane by the removal of one hydrogen atom. ...

Pelletier, Pierre Joseph

(Encyclopedia)Pelletier, Pierre Joseph pyĕr zhôzĕfˈ pĕlətyāˈ [key], 1788–1842, French chemist. With J. B. Caventou, he was cofounder of alkaloid chemistry and codiscoverer of quinine, strychnine, brucine,...

phenyl

(Encyclopedia)phenyl fĕnˈəl [key], C6H5, organic free radical or alkyl group derived from benzene by removing one hydrogen atom. ...

eutrophication

(Encyclopedia)eutrophication yo͞otrōˌfĭkāˈshən [key], aging of a lake by biological enrichment of its water. In a young lake the water is cold and clear, supporting little life. With time, streams draining i...

coenzyme

(Encyclopedia)coenzyme kō-ĕnˈzīm [key], any one of a group of relatively small organic molecules required for the catalytic function of certain enzymes. A coenzyme may either be attached by covalent bonds to a ...

tar and pitch

(Encyclopedia)tar and pitch, viscous, dark-brown to black substances obtained by the destructive distillation of coal, wood, petroleum, peat, and certain other organic materials. The heating or partial burning of w...

Soleri, Paolo

(Encyclopedia)Soleri, Paolo, 1919–2013, Italian-American architect. He studied architecture in his native Turin (Ph.D., 1946). Soleri's works have been influenced by both Frank Lloyd Wright, with whom he apprenti...

amino acid

(Encyclopedia)CE5 General formula of an amino acid CE5 Peptide bond between two molecules of the amino acid alanine amino acid əmēˈnō [key], any one of a class of simple organic compounds containin...

carbonate

(Encyclopedia)carbonate kärˈbənātˌ, –nət [key], chemical compound containing the carbonate radical or ion, CO3−2. Most familiar carbonates are salts that are formed by reacting an inorganic base (e.g., a ...