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Full-Text Articles in Physical Sciences and Mathematics
Speciation Of Technetium In Carbonate Media Under Helium Ions And Γ Radiation, Mohammad Ghalei, Johan Vandenborre, Frederic Poineau, Guillaume Blain, Pier-Lorenzo Solari, Jerome Rôques, Ferid Haddad, Massoud Fattahi
Speciation Of Technetium In Carbonate Media Under Helium Ions And Γ Radiation, Mohammad Ghalei, Johan Vandenborre, Frederic Poineau, Guillaume Blain, Pier-Lorenzo Solari, Jerome Rôques, Ferid Haddad, Massoud Fattahi
Chemistry and Biochemistry Faculty Research
Technetium carbonates complexes produced by chemical, electrochemical and radiolytic methods have been studied by UV-Visible, X-ray Absorption Fine Structure (XAFS) and Density Functional Theory methods. The (NH4)2TcCl6 salt was dissolved in 2 M KHCO3. The resulting purple solution was analyzed by XAFS and UV-Visible spectroscopy. The UV-Visible spectra exhibits a band centered at 515 nm. The XAFS results were consistent with the presence of polymeric species containing the [Tc2(μ−O)2]4+ core coordinated to carbonate ligand. Concerning the electrochemical methods, the pertechnetate anion was electrochemically reduced in concentrated carbonate solution [(CO32−)=5 M and (HCO3−)=0.5 M]. For the radiolytic reduction, the speciation of …
Holocene Climate Evolution Of Continental Western Eurasia Constrained By Stable-Isotope And Cation Geochemistry Of U-Th-Dated Speleothems And Meteogenic Travertine, Jonathan Lloyd Baker
Holocene Climate Evolution Of Continental Western Eurasia Constrained By Stable-Isotope And Cation Geochemistry Of U-Th-Dated Speleothems And Meteogenic Travertine, Jonathan Lloyd Baker
UNLV Theses, Dissertations, Professional Papers, and Capstones
Reliable reconstructions of global and regional climate during the Holocene (11,700 years ago to present) are vital to constraining the natural range of climate variability and testing state-of-the-art models, which seek to forecast the near- and long-term impact of anthropogenic greenhouse forcing. Much of continental Eurasia is still underrepresented, however, in geological proxy reconstructions of Holocene climate variability, and the vast majority of paleoclimate data only reflect conditions during peak summer months (JJA) or the growing season. The paucity of winter proxy data has therefore been cited as a possible explanation for the current mismatch between geological proxy-based and climate-model …