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  • Tritium
  • While some radioisotopes, such as strontium-90 (90Sr) and technetium-99 (99Tc), are only found on Earth as a result of human activity, and some, like potassium-40 (40K), are only present due to natural processes, a few isotopes, e.g. tritium (3H), result from both natural processes and human activities. (wikipedia.org)
  • In addition to the above light elements, tritium and isotopes of aluminium, carbon (carbon-14), chlorine, iodine and neon are formed within solar system materials through cosmic ray spallation, and are termed cosmogenic nuclides. (wikipedia.org)
  • citation needed
  • The basic approach is to label a candidate drug using the radioisotope carbon-14,[citation needed] and then administer the compound to human volunteers at levels typically about 100 times lower than the proposed therapeutic dosage (from around 1 to 100 micrograms but not above). (wikipedia.org)
  • Enclosure
  • Paper discusses the testing conducted on the Paramount Ductless Enclosure that shows carbon filter effectiveness and fume and particulate containment of particulates. (labconco.com)
  • Before you decide whether a carbon-filtered enclosure is appropriate for your application, fill out the Chemical Assessment form and submit it to us. (labconco.com)
  • nitrogen
  • The radioisotope carbon-14 is constantly formed from nitrogen-14 (14N) in the higher atmosphere by incoming cosmic rays which generate neutrons. (wikipedia.org)
  • Decarboxylation of L-tryptophan by aromatic L-amino acid decarboxylase (AADC) produces tryptamine (I), which contains a nucleophilic center at the C-2 carbon of the indole ring due to the adjacent nitrogen atom that enables the participation in a mannich-type reaction. (wikipedia.org)
  • Further work demonstrated that the coarse clay fraction had the greatest carbon to nitrogen ratio, greatest minimum residence time in the soil based on 14C radioisotope dating, and contained carbon most recalcitrant to microbial digestion. (wikipedia.org)
  • clay
  • In a study published in 2003, Gonzalez and Laird showed that new carbon derived from decomposing plant material tends to preferentially sorb to the fine clay subfraction of soil. (wikipedia.org)
  • Carbon sequestration in clay mineral fractions from 14C-labeled plant residues. (wikipedia.org)
  • nuclear
  • The bomb pulse is the sudden increase of carbon-14 (14C) in the Earth's atmosphere due to the hundreds of aboveground nuclear bombs tests that started in 1945 and intensified between 1950 until 1963, when the Limited Test Ban Treaty was signed by the United States, the Soviet Union and the United Kingdom. (wikipedia.org)
  • The glassy trinitite formed by the first atom bomb contains radioisotopes formed by neutron activation and nuclear fission. (wikipedia.org)
  • ratio
  • They have the same ratio of carbon-14 to carbon-12 as the atmosphere, and this same ratio is then carried up the food chain all the way to apex predators, like sharks. (abr-42.ru)
  • soil
  • Just because a radioisotope lands on the surface of the soil, does not mean it will enter the human food chain. (wikipedia.org)
  • More recent work has been focused on identifying pyrogenic carbon in soil with an emphasis on biochar soil application and studying the impact of biochar on soil properties. (wikipedia.org)
  • common
  • We have compared the structural formulae of various trichothecenes and suggest that the presence of substituents on carbon-15 of the common trichothecene ring may be important in determining the precise modes of action of this group of compounds. (mendeley.com)
  • Elements
  • As discussed above and in the Radiolab episode, Elements (section 'Carbon'), in bomb pulse dating the slow absorption of atmospheric 14C by the biosphere, can be considered as a chronometer. (wikipedia.org)
  • The boiling points of the carbon group tend to get lower with the heavier elements. (wikipedia.org)
  • Carbon, the lightest carbon group element, sublimates at 3825 °C. Silicon's boiling point is 3265 °C, germanium's is 2833 °C, tin's is 2602 °C, and lead's is 1749 °C. The melting points of the carbon group elements have roughly the same trend as their boiling points. (wikipedia.org)
  • The densities of the carbon group elements tend to increase with increasing atomic number. (wikipedia.org)