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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, Y.; Aydogmus, H. Yumurtaci; Usta, K.; Usta, A.; Ceylan, N.; Yilmaz, H.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.Öğe An EPR study on radiation-induced 4-hydroxyphenyl-acetic acid polycrystalline(ELSEVIER SCIENCE BV, 2015) Ceylan, Y.; Usta, K.; Usta, A.; Aydogmus, H. Yumurtaci; Guner, A.To determine of irradiation effect on 4-hydroxyphenyl-acetic acid polycrystalline, electron paramagnetic resonance (EPR) measurements were carried out. Two samples were used, which were given dose of 22.8 and 49 kGy by gamma rays using Co-60-source. EPR signals were not observed from irradiated sample, taken dose of 22.8 kGy. The measurements were performed on the sample, absorbed dose of 49 kGy, at the temperature between 120 K and 450 K. The two radical structures were suggested within experimental error. Though the radicals are identical, it was determined that they have different EPR parameters. It was observed that the intensities of the EPR spectra were to be dependent on the temperature. Also, in this study, it was aimed to test success of the machine learning methods to select the best method can be implemented theoretically. (C) 2015 Elsevier B.V. All rights reserved.Öğe An ESR Study on 2,4 Diaminotoluene Exposed to Gamma Rays and Application of Machine Learning(POLISH ACAD SCIENCES INST PHYSICS, 2016) Ceylan, Y.; Usta, K.; Aydogmus, H. Yumurtaci; Usta, A.; Ceylan, N.; Aras, E.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.