Abstract:Capelinha is a fluvial sambaqui (Brazilian Shell Mound) located in the Ribeira Valey in the State of São Paulo that is being studied. It is one of the oldest sambaquis located along a river dated so far in this region. The use of ESR to date other shells stimulated our group to apply this method to the Capelinha site. Shells from land snails (Megalobulimus sp.) obtained in two levels of excavations were analyzed; one of them was in contact with a skeleton that was dated by C-14. The archeological doses obtaine… Show more
“…Moreover, the hyperfine structure of the EPR spectrum (when it is well resolved) provides more important information about the radical than the g-value, because most radicals detected are carbon or nitrogen centered radicals and the spectra positions are almost in the same magnetic field range [1]. The EPR technique has been widely used for long time in the identification of irradiation damage centers in many substances including drugs, amino acid and iminodiacetic acid derivatives [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. L-glutamine and iminodiacetic acid powders were gamma-irradiated and studied by EPR at room temperature [19,20].…”
In this study, electron paramagnetic resonance spectroscopy was used to investigate free radicals formed in gamma irradiated L-glutamine hydrochloride, iminodiacetic acid hydrochloride and N-(2-hyroxyethyl) iminodiacetic acid powders. The free radicals produced in L-glutamine hydrochloride powders were attributed to the CH 2Ċ HCOOH radical; and those in iminodiacetic acid hydrochloride and N-(2-hyroxyethyl) iminodiacetic acid powders to the HNCHCH 2 (COOH) 2 and HOCH 2 CH 2 NĊHCH 2 (COOH) 2 , respectively. The g-values of the radicals and the hyperfine structure constants of the free electron with the environmental protons and 14 N nucleus were determined. The samples were not displayed before they were not irradiated. The free radicals were found stable at room temperature for more than six months. Some spectroscopic properties and suggestions concerning possible structure of the radicals are discussed in this paper.
“…Moreover, the hyperfine structure of the EPR spectrum (when it is well resolved) provides more important information about the radical than the g-value, because most radicals detected are carbon or nitrogen centered radicals and the spectra positions are almost in the same magnetic field range [1]. The EPR technique has been widely used for long time in the identification of irradiation damage centers in many substances including drugs, amino acid and iminodiacetic acid derivatives [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. L-glutamine and iminodiacetic acid powders were gamma-irradiated and studied by EPR at room temperature [19,20].…”
In this study, electron paramagnetic resonance spectroscopy was used to investigate free radicals formed in gamma irradiated L-glutamine hydrochloride, iminodiacetic acid hydrochloride and N-(2-hyroxyethyl) iminodiacetic acid powders. The free radicals produced in L-glutamine hydrochloride powders were attributed to the CH 2Ċ HCOOH radical; and those in iminodiacetic acid hydrochloride and N-(2-hyroxyethyl) iminodiacetic acid powders to the HNCHCH 2 (COOH) 2 and HOCH 2 CH 2 NĊHCH 2 (COOH) 2 , respectively. The g-values of the radicals and the hyperfine structure constants of the free electron with the environmental protons and 14 N nucleus were determined. The samples were not displayed before they were not irradiated. The free radicals were found stable at room temperature for more than six months. Some spectroscopic properties and suggestions concerning possible structure of the radicals are discussed in this paper.
“…In recent years, Electron Spin Resonance (ESR) technique has also been used for dating Quaternary fossils of mammals, human remains and shells of both marine and terrestrial molluscs (Molodkov, 1988; Barabas et al, 1992aBarabas et al, , 1992bMolodkov, 1993;Radtke, 1997, 1999;Engin et al, 2006;Kinoshita et al, 2006, Kerber et al, 2011. This technique is useful for Quaternary fossils because it can determine ages older than the maximum limit of 14 C (about 50,000 years) its upper limit is dependent on the saturation of defects and signal stability in older samples and on the thermal stability of the defects (Ikeya and Ohmura, 1981;Radtke et al, 1985;Shimokawa et al, 1992; Ikeya, 1993; Schellmann and Radtke , 1997;Lopes et al, 2013).…”
“…The electron paramagnetic resonance (EPR) has been widely used for the identification of irradiation damage centers in many substances including amino acid and their derivatives [5][6][7][8][9][10][11][12][13][14][15]. In previous study, Almanov et.al.…”
Powders of N-acetyl-L-leucine and N-methyl-L-glutamic acid were gamma irradiated and the free radicals formed were investigated at room temperature by electron paramagnetic resonance technique. The free radicals formed in compounds were attributed to the (CH 3 ) 2Ċ CH 2 CH(NHCOCH 3 )COOH and HOOCCH 2 CH 2Ċ (NHCH 3 )COOH radicals respectively. Both radicals are very stable and we could observe them for five months without almost intensity diminution at room temperature. The g values of the radicals and the hyperfine structure constants of the free electron with nearby protons and 14 N nucleus were determined. The results were found to be in good agreement with the existing literature data.
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