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    Öğe
    An EPR study on radiation-induced 2-(piperidin-1-ylmethyl) phenol single crystal
    (Polish Acad Sciences Inst Physics, 2016) Usta, Keziban; Ceylan, Yusuf; Usta, Ayhan; Ceylan, Nurufe; Aras, Erdal
    For the assessment of irradiation influence on 2-(piperidin-1-ylmethyl) phenol single crystals (C12H17NO), electron paramagnetic resonance measurements were carried out on the samples exposed to Co-60 radiation at dose values of 22.8, 45.6 and 68.4 kGy at room temperature. Electron paramagnetic resonance signals were not observed in non-irradiated sample and in samples irradiated at dose values of 22.8 and 45.6 kGy. The electron paramagnetic resonance measurements were performed on the single crystals. This irradiated single crystal was rotated in steps of 10 degrees. One type of radical center was found. The average values of g and hyperfine constant of the detected radiation damage center were calculated from experimental spectra as follows: g = 2.0052, A(H) = 0.74 mT.
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    Öğe
    An ESR study on 2,4 diaminotoluene exposed to gamma rays and application of machine learning
    (Polish Acad Sciences Inst Physics, 2016) Ceylan, Yusuf; Usta, Keziban; Aydoğmuş, Hacer Yumurtacı; Usta, Ayhan; Ceylan, Nurufe; Aras, Erdal
    The polycrystals of 2,4 diaminotoluene were produced by slow evaporation of solvent. The polycrystalline samples were exposed to Co-60 gamma rays with dose rate of 0.950 kGy/h, at room temperature, for 12, 24, 48, and 72 hours. The electron paramagnetic resonance measurements were carried out on these samples in the temperature range between 298 K and 400 K. No electron paramagnetic resonance signal was observed in the samples irradiated for 12, 24, 48 hours. Two types of radicals were detected using ESR spectrometer in the sample irradiated for 72 h. These radiation damage centers were called RI and RII. The average values of g and the hyperfine coupling constant were calculated. This study also investigates the potential usage of machine learning methods and aims to test the success of these methods and to select the best method.
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    Öğe
    Analysis of poly (2-Hydroxyethyl Methacrylate)-co-poly (4-Vinyl Pyridine) copolymers [COP2,4] irradiated: an EPR study
    (Polish Acad Sciences Inst Physics, 2016) Ceylan, Yusuf; Aydoğmus, Hacer Yumurtacı; Usta, Keziban; Usta, Ayhan; Ceylan, Nurufe; Yımaz, Hatice Cansu
    Poly(2-hydroxyethyl methacrylate)-co-poly(4-vinyl pyridine) and poly(HEMA)-co-poly-(4-VP) copolymers were synthesized by free radical polymerization. K2S2O8 was used as an initiator. Chain lengths of the copolymer was changed by varying the monomer/initiator ratio. These polymers have molarites of 2.6 and 2.1 respectively and are called COP2 and COP4. The samples were exposed to gamma rays at room temperature. After irradiation, the EPR spectra of COP2 and COP4 were recorded between 120 K and 450 K. From the temperature dependence of the line intensity, it was concluded that unpaired spin concentration in the irradiated samples has been changing with temperature. A theoretical study, presented in this report, was aimed to test success of the machine learning methods and to select the best learning method.