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  • 1
    ISSN: 1090-6487
    Schlagwort(e): 75.70.Pa ; 72.60.1g ; 61.12.Ld
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The evolution of the structural and magnetic properties of the CMR (colossal-magnetoresistance) compound La0.35Pr0.35Ca0.30MnO3 as the temperature changes from 10 to 293 K is investigated by means of neutron diffraction. It is shown that the changes in the transport and magnetic properties are directly related with the rearrangement of the atomic structure. A phase transition to the metallic state occurs together with simultaneous ferromagnetic ordering of the manganese moments and is accompanied by a jump in volume. The static distortions of the oxygen octahedra which are observed to occur prior to the magnetic phase transition and which are practically absent at room temperature and in the FM phase attest to the orbital ordering of oxygen atoms on the bonds, with freezing-in of the Jahn-Teller modes.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1619-7089
    Schlagwort(e): Radionuclide impurities ; Dose to the patient ; 99mTc-sodium pertechnetate ; Fission product 99Mo ; European Pharmacopoeia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Radionuclide impurities of radiopharmaceuticals do not provide any diagnostic information, but contribute to the radiation dose to the patient. For 99mTc, even small amounts of long lived radionuclide impurities may contribute significantly to the dose from 99mTc itself. In this preliminary study, estimates have been made for the radiation dose to specific organs and for the effective dose equivalent from impurities in 99mTc-sodium pertechnetate prepared from fission product 99Mo. In addition to 99Mo, 131I, 103Ru, 89Sr and 90Sr at maximum permissible levels as stipulated in the European Pharmacopoeia, 110mAg and 239Pu were taken as representative nuclides for beta-gamma emitters and alpha emitters. Using all of these radionuclides at such maximum permissible levels of impurity as stated in the European Pharmacopoeia, the total contribution from the impurities to the effective dose equivalent is approximately 30% of the effective dose equivalent from 99mTc-pertechnetate. In terms of specific organs, the liver and kidneys can receive doses of 3–4 times and 1–3 times the dose from 99mTc-pertechnetate itself. Although these are worst case calculations, a consistent approach should be reconsidered to limit the additional effective dose equivalent from impurities to e.g. 10% of the effective dose equivalent from 99mTc itself.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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