from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A heavy silvery-white metallic element, radioactive and toxic, easily oxidized, and having 14 known isotopes of which U 238 is the most abundant in nature. The element occurs in several minerals, including uraninite and carnotite, from which it is extracted and processed for use in research, nuclear fuels, and nuclear weapons. Atomic number 92; atomic weight 238.03; melting point 1,132°C; boiling point 3,818°C; specific gravity 18.95; valence 2, 3, 4, 5, 6. See Table at element.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The element with atomic number 92 and symbol U.
from the GNU version of the Collaborative International Dictionary of English
- n. An element of the chromium group, found in certain rare minerals, as pitchblende, uranite, etc., and reduced as a heavy, hard, nickel-white metal which is quite permanent. Its yellow oxide is used to impart to glass a delicate greenish-yellow tint which is accompanied by a strong fluorescence, and its black oxide is used as a pigment in porcelain painting. Symbol U. Atomic weight 239.
from The Century Dictionary and Cyclopedia
- n. Metallic uranium, as obtained in the fused condition by means of an electric furnace, is compact, white, and lustrous, capable of taking a high polish, of sp. gr. 18.7, melting at a very high temperature, and volatilizing more readily than iron, slowly acted upon by water at ordinary temperature, burning in oxygen or chlorin, and combining freely with nitrogen at 1000° C. The foundation was laid for the modern study of the phenomena of radioactivity when, in 1896, M. Henri Becquerel observed that a salt of uranium emits rays which affect a photographic plate screened by black paper opaque to ordinary light. This property proved to be common to all the salts of uranium and to uranium itself, and is exhibited continuously by uranium and its compounds even when they are kept in darkness. The intensity of the radiation is not materially affected by change of temperature within very wide limits. Not only are photographic effects produced by the radiation from uranium compounds, but positively or negatively electrified bodies, also, are discharged by ionization of the surrounding air. Subsequent investigation has shown that the uranium radiation is complex, and includes the emission of rays of the three types which have been designated as
α, β, and γrespectively. No condensible gaseous emanation is given off, as in the case of radium and of thorium, but the radioactivity of uranium involves the constant production of a new kind of matter, itself temporarily active. See uranium X. The recent study of radioactive minerals has shown that the amount of radium in a mineral is proportional to the amount of uranium present. Uranium is believed to be the parent or generating substance of an extensive series of radioactive elements which are successively produced by the atomic disintegration of the uranium. This series of products includes ionium, actinium, radium, and polonium. The final substance remaining after the radioactive transformations are concluded is supposed to be ordinary lead.
- n. Chemical symbol, U; atomic weight, 240. A metal discovered by Klaproth, in 1789, in a mineral which had been long known, and called pitch-blende, but which was supposed to be an ore of either zinc or iron.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a heavy toxic silvery-white radioactive metallic element; occurs in many isotopes; used for nuclear fuels and nuclear weapons
(One uranium nucleus consists of 92 protons and 146 neutrons and each neutron in uranium is bound on average by 8 MeV.)
The analysis of these particles indicates that the uranium is anthropogenic, i.e. that the material was produced as a result of chemical processing.
It does not, because 1/3 of the uranium is already in the bones, and not circulating in the blood for the kidneys to filter it. â€œTwenty to thirty percent of a toxic does of intravenous uranium could be found in the bones of male rats within 2.5 hours after administration, and 90% of the uranium retained by the body after 40 days was in bone [Neuman 1948a].
It does not, because 1/3 of the uranium is already in the bones, and not circulating in the blood for the kidneys to filter it.
U.S. State Department spokesman Mark Toner congratulated Moldova's government for the break up of what he called a uranium smuggling ring and said an FBI team had assisted Moldovan authorities with "technical analysis."
However, we are already taking the necessary step to remove highly enriched uranium from the country.
In addition, uranium is a finite fuel supply and its mining presents serious health risks.
There's also a pesky rumor from Italian intelligence that Iraq is buying huge quantities of yellowcake uranium from the country of Niger.
I wrote a couple of hundred pages about this testy old guy bucking against his growing dependence on others, who all blame his work in uranium for his illness.
Known for her confrontational style, Lauvergeon has turned Areva into the world's largest nuclear group, chiefly through acquisitions, with interests in uranium mines and the retreatment of spent nuclear fuel.
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