• radioactive
  • Ephraim Fischbach, a physics professor at Purdue, was looking into the rate of radioactive decay of several isotopes as a possible source of random numbers generated without any human input. (blogspot.com)
  • This rare but predictable form of carbon is radioactive, and it completely decays in about 55,000 years. (truth-out.org)
  • While the tool worked, Pittsburgh compound B relies on the use of carbon-11, a radioactive isotope with a half-life of 20 minutes that requires the immediate use of the material prepared in a cyclotron. (wikipedia.org)
  • Once they found a candidate dye, they attached the positron-emitting fluorine-18, a radioactive isotope with a half-life of nearly two hours that is used annually in two million PET scans and that can last for as long as a day when prepared in the morning by cyclotron. (wikipedia.org)
  • Radiolabeled with the radioactive isotope carbon-11 flumazenil may be used as a radioligand in neuroimaging with positron emission tomography to visualize the distribution of GABAA receptors in the human brain. (wikipedia.org)
  • ratio
  • In addition, there are at least three non-local individuals with higher values, including one with an extremely isotope ratio that cannot be from the Harappa region. (blogspot.com)
  • decays
  • The shortest-lived known isotope of lithium is lithium-4, which decays by proton emission with a half-life of about 6977909999999999999♠9.1×10−23 seconds, although the half-life of lithium-3 is yet to be determined, and is likely to be much shorter, like helium-2 (diproton) which undergoes proton decay within 6991100000000000000♠10−9 s. (wikipedia.org)
  • It is the shortest-lived known isotope of lithium, with a half-life of about 91 yoctoseconds, 6977909999999999999♠9.1×10−23 seconds and decays by proton emission to helium-3. (wikipedia.org)
  • organic
  • A gradient exists between trophic levels running from complete autotrophs that obtain their sole source of carbon from the atmosphere, to mixotrophs (such as carnivorous plants) that are autotrophic organisms that partially obtain organic matter from sources other than the atmosphere, and complete heterotrophs that must feed to obtain organic matter. (wikipedia.org)
  • Actinides can coordinate the organic active groups or bind to carbon by the covalent bonds. (wikipedia.org)
  • atomic
  • The unified atomic mass unit, symbol u, is defined being ​1⁄12 of the mass of a carbon-12 atom. (wikipedia.org)
  • For one sample, its relative atomic mass (atomic weight) is a straight average over the individual atom weights (isotopes) present. (wikipedia.org)
  • Relative atomic mass is determined by the average atomic mass, or the weighted mean of the atomic masses of all the atoms of a particular chemical element found in a particular sample, which is then compared to the atomic mass of carbon-12. (wikipedia.org)
  • Nevertheless, given the cost and difficulty of isotope analysis, it is usual to use the tabulated values of standard atomic weights which are ubiquitous in chemical laboratories. (wikipedia.org)
  • analysis
  • Based on this distribution of values, it would appear from our preliminary analysis that almost half of the individuals sampled from the Harappa cemetery have isotope values outside the local baseline (0.7158-0.7189). (blogspot.com)
  • For instance, imaging the cathodoluminescence emission from fast electrons can be used as a prescreening tool for high-resolution secondary-ion-mass spectrometry (SIMS) to image the zonation pattern and identify regions of interest for isotope analysis. (wikipedia.org)
  • data
  • As the researchers pored through published data on specific isotopes, they found disagreement in the measured decay rates - odd for supposed physical constants. (blogspot.com)
  • source
  • Amino acids also contribute to cellular energy metabolism by providing a carbon source for entry into the citric acid cycle (tricarboxylic acid cycle), especially when a primary source of energy, such as glucose, is scarce, or when cells undergo metabolic stress. (wikipedia.org)
  • tree rings
  • Over the last few decades, isotope geochemists have worked together with tree rings experts to construct a time series of atmospheric 14C variations over the last 10,000 years. (realclimate.org)
  • In some locations these trees have remained preserved and can be studied giving accurate radio-carbon dates, and the tree rings of the same long dead trees can be studied. (wikipedia.org)
  • process
  • Through a process called gaseous diffusion, isotopes of U-235 were separated from the predominant isotope, Uranium-238 by turning uranium metal into uranium hexaflouride gas and straining it through a barrier material. (wikipedia.org)
  • higher
  • On a contrary, K application affected leaf gas exchange physiology by increasing CO 2 assimilation rate and stomatal conductance thus leading to reduced leaf temperature and higher leaf water potential and carbon isotope discrimination (Δ). (edu.au)
  • materials
  • The Sigma-Aldrich ® commitment to carbon materials research and product development spans more than two decades. (sigmaaldrich.com)
  • A list of selected Sigma-Aldrich carbon materials and their physical characteristics are shown in the Table 1 . (sigmaaldrich.com)
  • energy
  • Both of the natural isotopes have an unexpectedly low nuclear binding energy per nucleon (~5.3 MeV) when compared with the adjacent lighter and heavier elements, helium (~7.1 MeV) and beryllium (~6.5 MeV). (wikipedia.org)
  • example
  • This concept is relied upon, for example, when anthropologists use carbon-14 to date ancient artifacts and when doctors determine the proper dose of radioactivity to treat a cancer patient. (blogspot.com)
  • small
  • Our carbon isotope time series from Caribbean sclerosponges start in the 15th century and show only very small variations until the early 19th century. (realclimate.org)