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Djerassi, Carl

(Encyclopedia)Djerassi, Carl jərăsˈē [key], 1929–2015, American organic chemist and educator, b. Vienna, Austria. He received his Ph.D. from the Univ. of Wisconsin (1945) and taught at Stanford Univ. from 195...

umbrella

(Encyclopedia)umbrella, a small canopy used as a protection against the sun in China, Egypt, and elsewhere in remote antiquity. It was often an emblem of rank. During the Middle Ages the umbrella became almost exti...

fumaric acid

(Encyclopedia)fumaric acid fyo͞omărˈĭk [key] or trans-butenedioic acid, HO2CCH=CHCO2H, unsaturated dicarboxylic acid that melts at 287℃. Maleic acid, or cis-butenedioic acid, is a geometric isomer of fumaric ...

tagua

(Encyclopedia)tagua täˈgwä [key], fruit of the ivory, or ivory-nut, palms (Phytelephas species), which flourish in tropical America from Paraguay to Panama. The female palms bear large woody, burrlike fruits, ea...

tamoxifen

(Encyclopedia)tamoxifen təmŏkˈsĭfĕnˌ [key], synthetic hormone used in the treatment of breast cancer. Introduced in 1978, tamoxifen is used to prevent recurrences of cancer in women who have already undergone...

perfluoroalkyl and polyfluoroalkyl substances

(Encyclopedia)perfluoroalkyl and polyfluoroalkyl substances (PFAS), a group of several thousand synthetic organic chemical compounds made up of a chain of carbon atoms bonded to fluorine atoms. PFAS, which resist w...

Bergius, Friedrich Karl Rudolf

(Encyclopedia)Bergius, Friedrich Karl Rudolf, 1884–1949, German chemist, Ph.D. Univ. of Leipzig, 1907. In 1910, Bergius set up a laboratory to carry out his research and in 1914 transferred the operation to the E...

bark cloth

(Encyclopedia)bark cloth, primitive fabric made in tropical and subtropical countries from the soft inner bark of certain trees. It has been made and used in parts of Africa and India, the Malay Peninsula, Samoa, t...

Narayanganj

(Encyclopedia)Narayanganj or Narayungunj both: näräˈyəngənj [key], city (1991 pop. 296,000), E central Bangladesh, at the confluence of the Lakhya and Dhaleshwari rivers. It is the river port for Dhaka and Ban...

Ashgabat

(Encyclopedia)Ashgabat əshkhəbätˈ [key], formerly Ashkhabad, city (2020 pop. 846,000), capital of Turkmenistan, near the border with Iran, on the Trans-Caspian RR. The city has text...