Hakkari Üniversitesi Akademik Veri Yönetim Sistemi
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Structural and Magnetic Characteristics of Hexylbenzene-Doped MgB2/Fe Superconducting Wires
No full textIn this study, the effect of 1 mol% hexylbenzene doping on the structural, thermal, and magnetic properties of MgB2/Fe superconducting wires was investigated. Differential scanning calorimetry (DSC) showed that the additive reduced the MgB2 formation temperature, while X-ray diffraction (XRD) analysis indicated decreased crystallite size (from 51.6 to 39.9 nm) and increased microstress. The superconducting transition temperature (Tc) decreased slightly from 38.6 K to 38.2 K, accompanied by a broader transition. The critical current density (Jc) of the doped sample was one order of magnitude lower, with values of ~ 105 A/cm2 at 5 K (self-field) in the pure wire compared to ~ 104 A/cm2 in the doped one. Flux pinning analysis revealed that the normalized pinning force (Fp/Fp,max) shifted to lower fields and weakened after doping, confirming the degradation of pinning efficiency. These results demonstrate that while hexylbenzene facilitates MgB2 phase formation, it negatively affects the superconducting performance of MgB2/Fe wires
Optics in spiral dislocation spacetime: torsion as a geometric waveguide and frequency-filtering mechanism
No full text We present an exact analytical study of nulltrajectories and scalar wave propagation in a (2 + 1)dimensional spacetime containing a spiral dislocation, atopological defect characterized by torsion in the absenceof curvature. For null rays, the torsion parameter β modifies the affine structure, enforcing a finite turning radiusrmin = b2−β2, and inducing a torsion-mediated angular deflection that decreases monotonically with increasingβ. The photon trajectory departs from the curvature-inducedlensing paradigm, exhibiting instead a purely topologicalexclusion zone around the defect core. Moreover, the resultscan, in principle, be mapped onto laboratory frames andconditions. In the wave regime, we recast the Helmholtzequation into a Schrödinger-like form and extract a spatially and spectrally dependent refractive index n2(r,k).Thisindex approaches unity asymptotically at large distances butdivergesstronglyandnegativelynearthedislocationcoredueto torsion-induced geometric contributions. The resultingrefractive index profile governs the transition from propagating to evanescent wave behavior, with low-frequency modesundergoing pronounced localization and suppression. Ourfindings demonstrate that torsion alone, even in the absenceof curvature, can act as a geometric regulator of both classical and quantum propagation, inducing effective anisotropy,frequency filtering, and confinement. This framework provides a rare exact realization of light-matter interaction in atorsion-dominated background, with potential applications in analog gravity systems and photonic metamaterials designedto emulate non-Riemannian geometries.</p
Durability of Laser-Glazed Environmental Barrier Coatings in the Corrosive Environment
No full textIn this study, the aim was to enhance the CMAS resistance and thermal cycling lifetime of the environmental barrier coating produced by the atmospheric plasma spray method (APS) through laser glazing. In plasma-sprayed environmental barrier coatings, the transition from an amorphous to a crystalline phase under operational conditions leads to deterioration, reducing their longevity. The surface of the YbSi coating, which was applied to the SiC substrate using APS, was modified using a CO2 laser that operated at 1.5 kW power, had a wavelength of 10.6 µm, and moved at a speed of 170 mm/s. Thermal cycle tests were conducted to examine the influence of laser surface modification on the thermal cycling performance of the coatings in corrosive conditions. Microstructures before and after laser surface alteration were analysed using SEM with EDS capability. XRD investigations were conducted to examine phase changes prior to and following thermal cycle tests. Laser glazing converted the amorphous phases in the YbSi layer into crystalline structures. XRD investigations were conducted to examine phase changes before and following thermal cycle tests. After laser glazing, the surface crystallinity of the extremely amorphous EBC coating increased by 39%. After surface modification, the surface roughness value of the coating was improved by roughly 40%, and the thermal cycle life was enhanced by up to 10 times. After the thermal cycling test in corrosive environment, cross-sectional EDS results showed that the development of corrosive salts such as V, Na, and Ca in the coated region was improved by at least 50%. Moreover, surface EDS data showed that after laser modification, corrosive salts accumulated more than in the unglazed sample
The role of thinking and problem-solving dispositions on the academic achievement of Turkish language teacher candidates
No full textIn this research, psychometric variables influencing the academic achievement of Turkishlanguage teacher candidates were examined. In this context, the study aimed to understandthe impact of variables believed to be related—such as problem-solving, critical thinking,creative thinking, and academic self-efficacy—on academic achievement, as well asthe relationships among these latent variables. A total of 368 volunteer Turkish languageteacher candidates from different universities participated in this study conducted in Turkey,and structural equation modeling was employed for data analysis. The study, conductedwith four different measurement tools, included validity and reliability studies forthe scales. Additionally, correlation values between the scales’ structures were provided.The analysis results revealed a positive and significant relationship between participants’problem-solving skills, critical and creative thinking tendencies, and academic self-efficacy.Furthermore, a significantly high correlation was observed among these psychometricvariables.</p
Role of anionic solution temperature on the electronic, linear/nonlinear optical properties and dispersion parameters of iron (III) oxide thin films
No full textIron (III) oxide (Fe2O3) thin films were deposited at different anionic solution temperatures (50 °C, 60 °C, and 70 °C) by the Successive Ionic Layer Adsorption and Reaction (SILAR) method to investigate the electronic, structural, linear/nonlinear optical properties, and dispersion parameters of Fe2O3 thin films. The electronic structure of 3d transition metal oxides was studied by Fe K-edge X-ray Absorption Spectroscopy (XAS), revealing insights into the interplay between metal 3d electrons, ligand interactions, and the influence of local atomic environments on electronic properties. The X-ray Diffraction (XRD) analysis were performed to find out the film structure. Morphology of thin film is determined by Field Emission-Scanning Electron Microscopy (FE-SEM). The linear optical constants of Fe2O3 films were determined from UV-vis results. The optical band gap and Urbach energy values of iron oxide thin films were determined as a function of increasing anionic solution temperature. The linear and nonlinear optical parameters, such as optical density, skin depth, nonlinear refractive index, and linear optical susceptibility, were analyzed in detail. The dispersion parameters such as effective single oscillator energy, dispersion energy and optical moment of thin films were discussed by using the Single Oscillator Model of Wemple and Di-Domenico. In addition, Sellmeier's oscillator parameter values were evaluated in detail
