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samarium

(Encyclopedia)samarium səmârˈēəm [key], metallic chemical element; symbol Sm; at. no. 62; at. wt. 150.36; m.p. 1,072℃; b.p. 1,791℃; sp. gr. 7.54 at 20℃; valence +2 or +3. Samarium is a lustrous silver-wh...

International Campaign to Abolish Nuclear Weapons

(Encyclopedia)International Campaign to Abolish Nuclear Weapons (ICAN), coalition of nongovernmental organizations that was formed in 2007 to advocate for the banning of nuclear weapons. It is based in Geneva, Swit...

ultrasonics

(Encyclopedia)ultrasonics, study and application of the energy of sound waves vibrating at frequencies greater than 20,000 cycles per second, i.e., beyond the range of human hearing. The application of sound energy...

polonium

(Encyclopedia)polonium pəlōˈnēəm [key], radioactive chemical element; symbol Po; at. no. 84; mass no. of most stable isotope 209; m.p. 254℃; b.p. 962℃; sp. gr. about 9.4; valence +2 or +4. Polonium is an e...

energy, sources of

(Encyclopedia)energy, sources of, origins of the power used for transportation, for heat and light in dwelling and working areas, and for the manufacture of goods of all kinds, among other applications. The develop...

Saint Andrews, University of

(Encyclopedia)Saint Andrews, University of, at St. Andrews, Scotland; founded 1410. It is the oldest university in Scotland. It has faculties of arts, science, and divinity. St. Salvator's College was founded in 14...

technetium

(Encyclopedia)technetium tĕknēˈshēəm [key] [Gr. technetos=artificial], artificially produced radioactive chemical element; symbol Tc; at. no. 43; mass no. of most stable isotope 98; m.p. 2,200℃; b.p. 4,877�...

Missouri, University of

(Encyclopedia)Missouri, University of, at Columbia (main campus), Rolla, Kansas City, and St. Louis; land-grant and state supported; coeducational; chartered 1839, opened 1841. It is the oldest state university W o...

zirconium

(Encyclopedia)zirconium zərkōˈnēəm [key], metallic chemical element; symbol Zr; at. no. 40; at. wt. 91.224; m.p. about 1,852℃; b.p. 4,377℃; sp. gr. 6.5 at 20℃; valence +2, +3, or +4. Zirconium is a very ...

Halden

(Encyclopedia)Halden hälˈdən [key], town, Østfold co., SE Norway, a port on the Iddefjord (an arm of th...