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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...

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...

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...

sapphire

(Encyclopedia)sapphire, precious stone. A transparent blue corundum, it is classified among the most valuable of gems. Sapphires are found chiefly in Madagascar, Sri Lanka, and Myanmar and also in Thailand, Tanzani...

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...

Álvarez Álvarez, Luis Héctor

(Encyclopedia)Álvarez Álvarez, Luis Héctor, 1919–2016, Mexican political leader and businessman, b. Camargo, Chihuahua state, Mexico. A textile industry executive, he was a member of the conservative National ...

Ansbach

(Encyclopedia)Ansbach änsˈbäkh [key], city, capital of Middle Franconia, Bavaria, S Germany, on the Rezat River. A rail and road junction, Ansbach has diversified industries, includi...

Haikou

(Encyclopedia)Haikou hoiˈhouˈ [key], city (1994 est. pop. 364,700), Hainan island, capital of Hainan prov., China. A seaport on Hainan Strait, it is the largest city on the island and an agricultural and light in...