Akduran N.,Ankara Nuclear Research And Training Center
Radiation Physics and Chemistry | Year: 2013
The Eu1Ba2Cu3O7 superconductor are synthesized using the solid state reaction method. The effect of gamma irradiation on transport properties and kinetic parameters of high-temperature ceramic Eu1Ba2Cu3O7 superconductor has been investigated. The bulk samples, prepared by the standard solid state reaction method, were irradiated by gamma rays of different doses in the range 0-30kGy at room temperature. Structure characterization using X-ray diffraction shows that decrease in the peak intensity represents a reduction in the content of the superconducting phase. The resistivity measurements are performed using the four-probe method in the temperature range from 77 to 300K. The changes in transition temperature show that Tc is very sensitive to gamma irradiation. The effects of irradiation on surface morphology have been investigated by scanning electron microscopy. The kinetic parameters have been estimated by thermogravimetric analysis. © 2012 Elsevier Ltd.
Aksu E.,Ankara Nuclear Research And Training Center
Journal of Alloys and Compounds | Year: 2013
MgB2 phase formation of samples with stoichiometric ratio of 1:2, prepared by sintering at different nine temperature values (500-900 °C) for 1 h were determined and examined by X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM) methods. In order to support the results obtained from the above measurements and analyses the Mg:B (1:2) powder was subject to thermal studies. In conjunction with this, the thermal behaviors of the non-sintered powder samples were also studied their characteristics via thermal analysis techniques including Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) simultaneously. During the thermal analyses, Mg:B (1:2) powder was placed in an Al2O3 cup with a lid were investigated at different heating rates (5, 7.5, 10, and 15°C/min) under high-purity Argon atmosphere. By analyzing the graphics gathered from the measurement results the effect of fundamental thermal events on MgB2 phase formation was deeply discussed by considering some data such as, crystallization, melting point, oxidation and evaporation, which can mainly be obtained from a usual thermal analysis technique. The peak temperatures of exothermic lines in DSC curves that indicate the formation of MgB2 were determined by derivative lines of the curves. With help of this information, the value of activation energy of MgB2 phase was found as EMgB2 = 219.9 kJ/mol by Kissinger Method. Moreover, in order to study the superconductivity of the samples; the sample sintered at 900 °C which was showing a considerable single phase property, was chosen for AC susceptibility measurement. For this sample, the onset temperature which is also called the transition temperature for superconductivity phase was found as Tc = 38.7 K. © 2012 Elsevier B.V. All rights reserved.
Zeyrek T.C.,Ankara Nuclear Research And Training Center
Journal of the Korean Chemical Society | Year: 2013
Optimized geometrical structure, atomic charges, molecular electrostatic potential, nonlinear optical (NLO) effects and thermodynamic properties of the title compound N-(2,5-methylphenyl)salicylaldimine (I) have been investigated by using ab initio quantum chemical computational studies. Calculated results showed that the enol form of (I) is more stable than keto form. The solvent effect was investigated for obtained molecular energies, hardneses and the atomic charge distributions of (I). Natural bond orbital and frontier molecular orbital analysis of the title compound were also performed. The total molecular dipole moment (μ), linear polarizability (α), and first-order hyperpolarizability (β) were calculated by B3LYP method with 6- 31G(d), 6-31+G(d,p), 6-31++G(d,p), 6-311+G(d) and 6-311++G(d,p) basis sets to investigate the NLO properties of the compound (I). The standard thermodynamic functions were obtained for the title compound with the temperature ranging from 200 to 450 K.
Tuncay F.,Ankara Nuclear Research And Training Center
Rheumatology International | Year: 2013
The aim of this study was to determine the intima-media thickness (IMT) in carotid arteries and to assess the relation of these values with plasma homocysteine (pHcy) levels and methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism in patients with Ankylosing spondylitis (AS). Serum lipids, vitamin B12, folic acid, pHcy and acute phase protein levels were measured in all cases. MTHFR C677T gene polymorphisms were determined, and IMT of main carotid artery were evaluated ultrasonographically in all subjects. Bath Ankylosing Spondylitis Disease Activity Index, Ankylosing Spondylitis Disease Activity score and Bath Ankylosing Spondylitis Metrology Index were used to assess disease activity and spinal mobility. Fifty AS patients (mean age of 36.6 ± 4.79 years) and 50 control subjects (36.34 ± 4.72 years) were included in the study. Plasma homocysteine levels of AS patients and control group were also similar (14.26 ± 9.96 vs. 11.81 ± 5.53 μmol/L). Hyperhomocysteinemia was present in 11 subjects in patient group (22.0 %), while it was seen in 5 subjects in the control group (10.0 %). The MTHFR C677T genotype distribution was as follows: CC 31 (62 %), CT 14 (28 %), TT 5 (10 %) in AS patients. The mean carotid IMT values were also found to be similar between the groups. The most important factor influencing pHcy level was found as MTHFR 677TT genotype. We indicated no difference of atherosclerosis indices revealed by IMT values and pHcy levels AS patients and control subjects. But an association between MTHFR 677 gene polymorphism and pHcy levels was concluded, which may suggest that MTHFR 677 TT polymorphism may be a potential prognostic factor for cardiovascular disease in patients with AS. © 2012 Springer-Verlag Berlin Heidelberg.
Akinci E.,Ankara Nuclear Research And Training Center
The American journal of emergency medicine | Year: 2011
Mexiletine is a class IB antiarrhythmic agent. Although it is primarily used in treating ventricular arrhythmias, recent indications for use of mexiletine include chronic and neuropathic pains. At high doses, mexiletine causes drowsiness, confusion, nausea, hypotension, sinus bradycardia, paresthesia, seizures, bundle branch block, atrioventricular heart block, ventricular arrhythmias, asystole, cardiovascular collapse, and coma. A 23-year-old male patient presented to the emergency department with intentional ingestion of high-dose mexiletine. Despite decontamination and supportive treatment, his vitals deteriorated during the observation period; and he developed stupor and dysarthria. Patient then underwent hemodialysis. His vital signs and overall condition improved rapidly following hemodialysis treatment. In this case report, we aimed to emphasize hemodialysis as a useful alternative therapy for severe mexiletine intoxications. Copyright © 2011 Elsevier Inc. All rights reserved.