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  • neutrons
  • This operation, until 1943 the only large-scale method used, has been superseded by less expensive processes, such as fractional distillation (D 2 O becomes concentrated in the liquid residue because it is less volatile than H 2 O). The heavy water produced is used as a moderator of neutrons in nuclear power plants. (britannica.com)
  • uranium
  • Simultaneously, he also worked under Harold C. Urey, the 1934 Nobel chemistry laureate, at Columbia University to develop methods for separating uranium isotopes by gaseous diffusion for production of the bomb. (encyclopedia.com)
  • These heavy water reactors have the advantage of being able to run on natural uranium without using graphite moderators that pose radiological and dust explosion hazards in the decommissioning phase. (wikipedia.org)
  • Nuclear fission of uranium and plutonium produces the radioactive isotope 140 Ba, which is used as a radioactive tracer. (thefreedictionary.com)
  • An important example of this process is the way isotopes were used to purify uranium during World War II (1939 - 45). (encyclopedia.com)
  • Two common isotopes of uranium exist, 235 U and 238 U. Of these two, 238 U is much more abundant, making up about 99.3 percent of the uranium found in nature. (encyclopedia.com)
  • Researchers found that the 235 U in the natural uranium was slightly less heavy than the 238 U, so it diffused through the barrier slightly more quickly. (encyclopedia.com)
  • However, science would be very different and much more ignorant (isotopic dating techniques, such as carbon, uranium, etc. would not exist), medicine wouldn't be as advanced (diagnostic [tracer] and theraputic radionuclides would be much rarer), and, worse of all, we health physicists would be out of a job fairly quickly :) Great question! (madsci.org)
  • nuclear
  • Since then, heavy water has been an essential component in some types of reactors, both those that generate power and those designed to produce isotopes for nuclear weapons. (wikipedia.org)
  • The only element whose isotopes have names, hydrogen has long been considered as a potential source of power and transportation: once upon a time for airships, later as a component in nuclear reactions - and, perhaps in the future, as a source of abundant clean energy. (encyclopedia.com)
  • This operation, until 1943 the only large-scale method used, has been superseded by less expensive processes, such as fractional distillation (D 2 O becomes concentrated in the liquid residue because it is less volatile than H 2 O). The heavy water produced is used as a moderator of neutrons in nuclear power plants. (britannica.com)
  • Groundwater
  • Tracers also can be used to determine groundwater age. (encyclopedia.com)
  • Introduced tracers, such as dyes or chloride, are used to determine the direction and rate at which groundwater moves, the rate at which river-water flows, and mixing characteristics. (encyclopedia.com)
  • Arrival of the tracer at a nearby well indicates movement of groundwater from the injection well toward that well, and thus allows determination of direction and rate of groundwater flow. (encyclopedia.com)
  • By knowing the proportions of heavy and light oxygen isotopes in precipitation and in irrigation water, hydrologists can calculate how much of the groundwater originated from each of these two sources. (encyclopedia.com)
  • Hydrogeochemical investigations and spatial variations studies on the distribution of water isotopes and radiocarbon in the groundwater of Žitný Island (Rye Island) were carried out. (environmental-expert.com)
  • signatures
  • Chapter 5 examines Mg-cycling in the 'critical zone' with the aim of deciphering whether or not first-order streams exhibit plant-fractionated Mg isotope signatures. (usask.ca)
  • For instance, previous work has shown that fully mycoheterotrophic plants that associate with ectomycorrhizal fungi are significantly enriched in the heavy isotopes of carbon and nitrogen compared to autotrophic understory plants, and they have carbon and nitrogen isotope signatures similar to, or more enriched than ectomycorrhizal fungi. (berkeley.edu)
  • 2002) to document these Zn isotope signatures focused on mammal organs with further primary research focusing on humans by Helal et al. (rsc.org)
  • geochemical
  • This study emphasizes the problem of misinterpreting stratigraphic trends in Mg, Ca, and C isotope profiles as genuine reflections of global-scale changes in the geochemical cycling of these elements. (usask.ca)
  • Isotopic tracers are more specialized and are often used in conjunction with geochemical analysis. (gwadi.org)
  • Based on radiometric dating and geochemical isotope analysis, Czaja characterizes his fossils as having formed in this early Vaalbara supercontinent in an ancient deep seabed containing sulfate from continental rock. (wattsupwiththat.com)
  • fractionation
  • There is no evidence in a studied sugar maple stand for Mg isotope fractionation associated with uptake from soil solutions into mature trees and seedlings. (usask.ca)
  • However, our poor understanding of the variability of Zn distribution among the different organs and fluids of the human body, and the ensuing isotope fractionation, limits the use of this isotopic system as a typical diagnostic tool for cancers and for past hominin diet reconstructions. (rsc.org)
  • 10,11 Nevertheless, Zn homeostasis and its bearing on the mechanisms of Zn isotope fractionation in the human body remain poorly investigated. (rsc.org)
  • 12 Zn isotope fractionation is controlled by the coordination of Zn with the different ligands in the body tissues. (rsc.org)
  • ratio
  • Once the charges are determined, the detector can tell to which element each ion belongs and counts the desired isotope as a ratio of a more abundant isotope-carbon-14 as a ratio of carbon-13, for example. (llnl.gov)
  • Estimation of the isotopic turnover rate in the tissues of organisms allows us to estimate the temporal relationship between the isotope ratio of an organism and its prey, and to analyze seasonal variations of food webs and migratory patterns of animals. (environmental-expert.com)
  • In addition the oxygen isotope ratio of solid phases (e.g. carbonate minerals) can record paleo-climate and paleo-hydrologic information. (arizona.edu)
  • dyes
  • Artificial radioisotopes may be used similarly as a logical extension to well-known tracer techniques using dyes and salts. (osti.gov)
  • water
  • We show for the first time the effects of heavy-hydrogen water ( 2 H 2 O) and heavy-oxygen water (H 2 18 O) on the gliding speed of microtubules on kinesin-1 coated surfaces. (peerj.com)
  • Increased fractions of isotopic waters used in the motility solution decreased the gliding speed of microtubules by a maximum of 21% for heavy-hydrogen and 5% for heavy-oxygen water. (peerj.com)
  • We also show that gliding microtubule speed returns to its original speed after being treated with heavy-hydrogen water. (peerj.com)
  • In this study, we show the effects of changing the water isotope has on the speed of gliding microtubules using kinesin-1. (peerj.com)
  • 2003 ) also showed a 60% reduction in in vitro actin gliding velocity in heavy-hydrogen water. (peerj.com)
  • We are unaware of prior studies involving use of water isotopes as osmotic stressors using the kinesin and microtubule system. (peerj.com)
  • Heavy-hydrogen water stabilizes polymerized microtubules, which has been shown to be a likely reason for why deuterium oxide is highly toxic to eukaryotic organisms ( Kushner, Baker & Dunstall, 1999 ). (peerj.com)
  • Heavy water is not radioactive . (wikipedia.org)
  • The human body naturally contains deuterium equivalent to about five grams of heavy water, which is harmless. (wikipedia.org)
  • 50%) in higher organisms is replaced by heavy water, the result is cell dysfunction and death. (wikipedia.org)
  • Heavy water was first produced in 1932, a few months after the discovery of deuterium. (wikipedia.org)
  • Tracers primarily are used to determine the direction and rate of water movement. (encyclopedia.com)
  • Heavy water, which consists of deuterium in the place of regular hydrogen, was discovered by Urey's group in 1932. (edu.jm)
  • We begin to have a more complex understanding of water when we realize the potential of these chemical and isotopic tracers to answer questions about the water's age, origin, and movement. (gwadi.org)
  • Evidence of heavy metal incorporation and release, electron transfer between phases and through bulk solids, and the observation of recrystallization on the surface of the substrate mineral structures have positively confirmed the catalytic effects of aqueous Fe(II) on mineral-water interactions. (semanticscholar.org)
  • Soon after deuterium's discovery, Urey and others produced samples of " heavy water " in which the deuterium content had been highly concentrated. (wikipedia.org)
  • In the laboratory heavy water is employed as an isotopic tracer in studies of chemical and biochemical processes. (britannica.com)
  • We cannot live long with large quantities of hydrogen(2) dioxide (deuterium dioxide, or heavy water), because the chemical rate constants which determine how water (etc.) is distributed in our bodies are based on "normal" water. (madsci.org)
  • abundance
  • AMS is an exceptionally sensitive technique for measuring concentrations of isotopes in small samples, typically less than 1 milligram, and the relative abundance of isotopes at low levels. (llnl.gov)
  • unstable
  • Hydrogen has three naturally occurring isotopes, denoted 1 H, 2 H and 3 H. Other, highly unstable nuclei ( 4 H to 7 H) have been synthesized in the laboratory but are not observed in nature. (edu.jm)
  • enrichment
  • This enrichment is due to the greater solubility of the heavier noble gases, so they are more readily dissolved into the solvent used for capture. (epsrc.ac.uk)
  • The process is in equilibrium in both instances, but the rate of these exchanges is different, so that enrichment of one of the isotopes results. (arizona.edu)
  • occur
  • This is thought to be a result of natural isotope separation processes that occur from solar heating of ices in comets. (wikipedia.org)
  • concentrations
  • Similar enrichments in heavy noble gases, along with high helium concentrations are well documented in coals, coal-bed methane and in organic rich oil and gas source rocks. (epsrc.ac.uk)
  • element
  • A cryogenic facility for high-efficiency separation of hydrogen isotopes with a cryogenic distillation column as the main element is described. (ebscohost.com)
  • Hydrogen is the only element that has different names for its isotopes in common use today. (edu.jm)
  • The LLNL heavy element group has been investigating the chemical properties of the heaviest elements over the past several years. (unt.edu)
  • waters
  • We also discuss the implication for using heavy waters in biomolecular devices incorporating molecular motors. (peerj.com)
  • fungi
  • It is speculated that these fungi are important vectors in the uptake of Mg into tree fine roots in natural settings, and that the fungi do not fractionate Mg isotopes. (usask.ca)
  • investigate
  • The aim of the research project is to investigate, on the basis of historical-geographic reconstructions and chemical analyzes, the potential environmental impact of heavy metals related to the First World War, fought on some localized sites in the glacial Alpine environment of the mountain range Marmolada, Adamello-Presanella and Ortles - Cevedale. (unipd.it)
  • Chapters 2 and 3 investigate Mg isotopes as tracers of fluid flow during dolomitization. (usask.ca)