|a stew of meat, vegetables, potatoes, etc.|
|a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.|
|1.||printing new paragraph|
|2.||law nisi prius|
|3.||no place of publication|
|—the internet domain name for|
|—the chemical symbol for|
|3.||Also: np Notary Public|
The symbol for the element neptunium.
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|neptunium (něp-t'nē-əm) Pronunciation Key
A silvery, radioactive metallic element of the actinide series. It occurs naturally in minute amounts in uranium ores and is produced artificially as a byproduct of plutonium production. Its longest-lived isotope is Np 237 with a half-life of 2.1 million years. Atomic number 93. See Periodic Table.
The symbol for neptunium.
No problem definition
radioactive chemical element of the actinoid series of the periodic table, first transuranium element to be artificially produced, atomic number 93. Though traces of neptunium have subsequently been found in nature, where it is not primeval but produced by neutron-induced transmutation reactions in uranium ores, Edwin M. McMillan and Philip H. Abelson first found neptunium in 1940 after uranium had been bombarded by neutrons from the cyclotron at Berkeley, Calif. Neptunium has been produced in weighable amounts in breeder reactors as a by-product of plutonium production from uranium-238 (about one part neptunium is produced for every 1,000 parts plutonium). All neptunium isotopes are radioactive; the stablest is neptunium-237, with a half-life of 2,140,000 years, and among the most unstable is neptunium-232, with a half-life of 13 minutes.
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