Browsing by Subject "Isotopes"

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    Differences in the accumulation and distribution profile of heavy metals and metalloid between male and female crayfish (Astacus leptodactylus)
    (2013) Tunca, E.; Ucuncu, E.; Ozkan, A.D.; Ulger, Z.E.; Cansizoǧlu, A.E.; Tekinay, T.
    Concentrations of selected heavy metals and a metalloid were measured by ICP-MS in crayfish (Astacus leptodactylus) collected from Lake Hirfanli, Turkey. Aluminum (Al), chromium (52Cr, 53Cr), copper ( 63Cu, 65Cu), manganese (Mn), nickel (Ni) and arsenic (As) were measured in the exoskeleton, gills, hepatopancreas and abdominal muscle tissues of 60 crayfish of both genders. With the exception of Al, differences were determined between male and female cohorts for the accumulation trends of the above-mentioned elements in the four tissues. It was also noted that the accumulation rates of Ni and As were significantly lower in gill tissue of females compared to males and no significant difference was observed for Cu isotopes in female crayfish. Cluster Analysis (CA) recovered similar results for both genders, with links between accumulations of Ni and As being notable. Accumulation models were described separately for male and female crayfish using regression analysis, and are presented for models where R2 > 0.85. © 2013 Springer Science+Business Media New York.
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    Isotope Effect and Phonon Softening in Superconducting Borocarbides and Boronitrides
    (1998) Hakioǧlu, Tuğrul; Ivanov, V. A.
    The isotope effect in the recently disvovered class o superconductors LuNi2B2C and La3Ni2B2N3 is investigated in the context of electron-squezed phonon interaction renormalizing the Ni-d electron-electron correlations. Squeezed phonon mode originates from the anharmonic character of the tetragonal Ni-B structure and is polarized in the vortical direction to the Ni layers. The isotope effect arises as a result of the zero point motion of the Ni-Ni d-electron hopping amplitude dominantly due to this vertical phonon mode. Within this model the isotope exponent is calculated to be αB ≤ 0.20 as compared to the recently found experimental value αexp B=0.27∓0.10. Finally, the phonon frequency softening predicted by our model eletron-phonon interaction is discussed within the context of recent experiments on the relevant boron A1g softening.