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specific heat

(Encyclopedia)specific heat, ratio of the heat capacity of a substance to the heat capacity of a reference substance, usually water. Heat capacity is the amount of heat needed to change the temperature of a unit ma...

Purcell, Edward Mills

(Encyclopedia)Purcell, Edward Mills, 1912–97, American physicist, b. Taylorville, Ill., Ph.D. Harvard, 1938. During World War II, Purcell was a researcher at the Massachusetts Institute of Technology Radiation La...

transuranium elements

(Encyclopedia)transuranium elements, in chemistry, radioactive elements with atomic numbers greater than that of uranium (at. no. 92). All the transuranium elements of the actinide series were discovered as synthet...

polybrominated biphenyl

(Encyclopedia)polybrominated biphenyl or PBB, any of a group of organic compounds used as a fire retardant. In 1973 several thousand pounds of PBB were accidentally mixed with livestock feed that was later distribu...

Hiroshima

(Encyclopedia)Hiroshima hĭrˌōshēˈmə, hērōˈshmä [key], city, capital of Hiroshima prefectu...

Compton, Arthur Holly

(Encyclopedia)Compton, Arthur Holly, 1892–1962, American physicist, b. Wooster, Ohio, grad. College of Wooster (B.S., 1913), Ph.D. Princeton, 1916. He was professor and head of the department of physics at Washin...

Bohr, Aage Niels

(Encyclopedia)Bohr, Aage Niels ägə nēls bōr [key], 1922–2009, Danish physicist, Ph.D. Univ. of Copenhagen, 1954. He worked with his father Niels Bohr (who won the Nobel Prize in Physics in 1922) in the 1940s ...

Bethe, Hans Albrecht

(Encyclopedia)Bethe, Hans Albrecht bāˈtə [key], 1906–2005, American physicist, b. Strassburg, Germany (now Strasbourg, France), educated at Frankfurt and Munich universities. Fleeing Nazi Germany in 1933, he c...

Perrin, Jean Baptiste

(Encyclopedia)Perrin, Jean Baptiste zhäN bätēstˈ pĕrăNˈ [key], 1870–1942, French physicist. From 1910 to 1940 he was professor at the Univ. of Paris, and in 1941 he came to the United States. Perrin specia...

actinide series

(Encyclopedia)actinide series, a series of radioactive metallic elements in Group 3 of the periodic table. Members of the series are often called actinides, although actinium (at. no. 89) is not always considered a...