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  • Enzyme digestion  (1)
  • LUNAR AND PLANETARY EXPLORATION  (1)
  • 2010-2014
  • 1975-1979  (2)
  • 1950-1954
  • 1977  (2)
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Publisher
Years
  • 2010-2014
  • 1975-1979  (2)
  • 1950-1954
Year
  • 1
    Publication Date: 2019-07-13
    Description: Ca has been measured in a lunar soil in order to establish the presence of isotopically mass-fractionated components. Ca was extracted by a series of water leaches after the soils were 'activated' by brief exposures to fluorine gas. The O2 obtained by this fluorination is found to have delta (O-18) of +21 per mil and to be, therefore, significantly mass-fractionated. Ca obtained in the leaches was analyzed using the double-spike technique. Very small Ca isotope fractionation is found in the leaches of this soil of up to 1 per mil per mass unit difference. The small Ca effects are in marked contrast to the measured delta (O-18) for the same sample and to large effects observed in many soils for oxygen, silicon, sulfur, and potassium. The data on Ca provide stringent constraints on models which attempt to explain the isotope mass-fractionation effects in lunar soils.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar Science Conference; Mar 14, 1977 - Mar 18, 1977; Houston, TX
    Format: text
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 184 (1977), S. 155-167 
    ISSN: 1432-0878
    Keywords: Epidermal cell differentiation ; DNA and RNA ; GMA embedded tissue ; Enzyme digestion ; Schiff-Thallium reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of nucleic acids within nuclei of epidermal cells in skin from guinea-pig ear was investigated using an indirect enzyme digestion technique to observe both DNA and RNA, and a direct Schiff-Thallium reaction technique, to observe DNA alone. Similar results were obtained by both methods. The distribution of DNA and RNA change gradually in nuclei as epidermal cells differentiate. DNA in cells of the lower strata is localized in essentially the same areas in which electron-opaque components are seen by conventional electron microscopy. With the cytochemical treatments, however, we found that DNA is not present in all electron-opaque areas of nuclei in superficial granular cells. RNA is present in the nucleoli of cells in all layers, but its density is also lower in the upper granular cells. We postulate that nucleic acids in nuclei of granular cells gradually decrease and that the space is filled with newly synthesized electron-dense protein, as part of the differentiation process.
    Type of Medium: Electronic Resource
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