• 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)
  • 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)
  • theoretical
  • This application note discusses the factors affecting the life of a carbon filter and a formula for calculating the theoretical filter life. (labconco.com)
  • Chemical
  • 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)
  • Form
  • Oh I know that you might say well what about this carbon dating which says that the earth has been in existence millions of years, well one thing that you have to remember is that the material which goes up to make the earth has indeed been in existence for much longer than the earth in its present form. (abovetopsecret.com)
  • Bomb pulse dating should be considered a special form of carbon dating. (wikipedia.org)
  • Carbon alone forms negative ions, in the form of carbide (C4−) ions. (wikipedia.org)
  • The most common is graphite, which is carbon in the form of stacked sheets. (wikipedia.org)
  • Another form of carbon is diamond, but this is relatively rare. (wikipedia.org)
  • 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)
  • 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)
  • 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)
  • human
  • He has contributed major advances on the entire spectrum of research from fundamental chemistry methodology with radioisotopes to human neuroimaging. (wikipedia.org)