Unal H.,Balkesir University |
Gulseren O.,Bilkent University |
Ellialtolu A.,Ankara University |
Mete E.,Balkesir University
Physical Review B - Condensed Matter and Materials Physics | Year: 2014
The electronic properties of quasi-one-dimensional anatase TiO2 nanostructures, in the form of thin nanowires having (101) and (001) facets, have been systematically investigated using the standard, hybrid density functional and quasiparticle calculations. Their visible photoabsorption characteristics have also been studied at these levels of theories. The thin stoichiometric nanowire models are predicted to have larger band gaps relative to their bulk values. The band-gap-related features appear to be better described with the screened Coulomb hybrid density functional method compared to the standard exchange-correlation schemes. Depending on the self-consistency in the perturbative GW methods, even larger energy corrections have been obtained for the band gaps of both (101) and (001) titanium dioxide nanowires. © 2014 American Physical Society.
Coban C.,Balkesir University |
Colakoglu K.,Gazi University |
Ciftci Y.O.,Gazi University
Journal of Physics and Chemistry of Solids | Year: 2012
The structural and lattice dynamical properties of TmX (X=As, P) compounds were investigated using normconserving pseudopotentials within the generalized gradient approximation correction (GGA) of Perdew-Burke-Ernzerhof (PBE) in the framework of density functional theory (DFT). The structural parameters (a 0, B, B′, E coh) were determined through total energy and interatomic force minimization and the overall agreement was found to be good. The pressure dependence of the ratios of normalized lattice parameters a/a 0, normalized volume V/V 0, bulk modulus, elastic constants, Zener anisotropy factor, Poissons ratio, Youngs modulus, shear modulus, and the brittleness were presented and discussed. The thermodynamical properties such as thermal expansion, heat capacity, Debye temperature, and Grüneisen parameter were calculated employing the quasi-harmonic Debye model at different temperatures (0-1000 K) and pressures (0-30 GPa). The phonon dispersion curves and corresponding density of states (DOS) of TmX (X=As, P) were also obtained, and the salient results were interpreted. © 2012 Elsevier Ltd.
Mete E.,Balkesir University |
Dansman M.F.,Middle East Technical University
Journal of Physical Chemistry C | Year: 2015
Here we present a density functional theory study of pentacene ultrathin films on flat and vicinal [(455)] Au(111) surfaces. We have performed crystal and electronic structure calculations by using PBE and optB86b-vdW functionals and investigated the effects of long-range van der Waals interactions for different coverages starting from a single isolated molecule up to 4 monolayers of coverage. For an isolated molecule both functionals yield the hollow site as the most stable one with the bridge-60 site being very close in energy in the case of optB86b-vdW. Binding strength of an isolated pentacene on the step edge was found to be much larger than that on the terrace sites. Different experimentally reported monolayer structures were compared and the (6 × 3) unit cell was found to be energetically more stable than the (2 × 2 7) and (2 × 31) ones. For one monolayer films while dispersion corrected calculations favored flat pentacene molecules on terraces, standard (PBE) calculations either found tilted and flat configurations to be energetically similar (on the flat (111) surface) or favored the tilted configuration (on the (455) surface). PDOS calculations performed with the optB86b-vdW functional showed larger dispersion of molecular orbitals over the Au states for the (455) surface when compared with the flat (111) surface, indicating an enhanced charge carrier transport at the pentacene-gold interface in favor of the vicinal surface. Starting with the second monolayer, both functionals favored tilted configurations for both surfaces. Our results underline the importance of the dispersion corrections for the loosely bound systems like pentacene on gold and the role played by step edges in determining the multilayer film structure and charge transfer at the organic molecule-metal interface. © 2015 American Chemical Society.
Eser B.,Balkesir University |
Sahin N.,Balkesir University
Clinical Rheumatology | Year: 2016
Rheumatoid arthritis (RA) is a progressive inflammatory disease. Although the etiology and pathogenesis of RA are not known well, genetic and environmental factors are proposed to initiate an autoimmune process. We aimed to investigate mRNA expression levels of Toll-like receptor-2 (TLR-2), TLR-4, and interleukin-6 (IL-6) genes in RA disease. This study was conducted with 50 patients who were diagnosed with RA according to the American College of Rheumatology classification criteria for RA and 50 age-matched healthy control individuals who did not have any joint diseases and autoimmune diseases. We collected whole blood from all participants and analyzed expression of TLR-2, TLR-4, and IL-6 genes at mRNA level using real-time qPCR. TLR-2 expression was detected to increase 3.8-fold and IL-6 expression was detected to increase 6.8-fold in RA patients compared to healthy controls. No difference was found between patient and control groups with regard to TLR-4 expression. Overexpression of TLR-2 and IL-6 may be responsible for RA pathogenesis. Inhibition of both TLR and IL signaling pathways may prevent joint inflammation and destruction. © 2016 International League of Associations for Rheumatology (ILAR)
Aydin S.,Balkesir University
Computer Assisted Language Learning | Year: 2015
This study presents a review of the literature that examines WebQuests as tools for second-language acquisition and foreign language-learning processes to guide teachers in their teaching activities and researchers in further research on the issue. The study first introduces the theoretical background behind WebQuest use in the mentioned processes. It then reviews studies that examine WebQuests as tools used in second-language acquisition and foreign language-learning processes. The study concludes that WebQuest use improves interaction, communication, critical thinking, knowledge application, social skills, scaffolded learning, higher order thinking skills and problem-solving skills. Moreover, WebQuests help learners to acquire and learn linguistic and extra-linguistic knowledge in a secure atmosphere in the processes of second-language acquisition and foreign language learning. Second, the results of the reviewed studies show that WebQuests have positive effects on reading skills and vocabulary knowledge. The paper ends with practical recommendations for teachers and researchers. © 2015 Taylor & Francis
Evirgen F.,Balkesir University |
Ozdemir N.,Balkesir University
Journal of Computational and Nonlinear Dynamics | Year: 2011
This paper deals with implementation of the multistage Adomian decomposition method (MADM) to solve a class of nonlinear programming (NLP) problems, which are reformulated with a nonlinear system of fractional differential equations. The multistage strategy is used to investigate the relation between an equilibrium point of the fractional order dynamical system and an optimal solution of the NLP problem. The preference of the method lies in the fact that the multistage strategy gives this relation in an arbitrary longtime interval, while the Adomian decomposition method (ADM) gives the optimal solution just only in the neighborhood of the initial time. The numerical results taken by the fractional order MADM show that these results are compatible with the solution of NLP problem rather than the ADM. Furthermore, in some cases the fractional order MADM can perform more rapid convergency to the optimal solution of optimization problem than the integer order ones. © 2011 American Society of Mechanical Engineers.
Saritas S.,Balkesir University
Turkish Online Journal of Educational Technology | Year: 2015
No matter who we are or where we live, our lives revolve around food, which is much more than a merely sustenance. As a part of the human culture, food carries complex significance and symbolic meanings. Turkish people attribute great value to food and its usage specifically tied to rites of passage of human life. Traditions, especially the ones practiced during rites of passage, such as birth, circumcisions, weddings and funerals, have always been accompanied by food in Turkish culture. Since food celebrates and symbolizes human progress in life in the culture, it also surrounds by aspects of belief, custom, magic, ritual and religion and has always been used in ceremonial context during such rites. Even though that context may be different depending on the religious, economic and social nuances of the various Turkish regions, like wheat, meat and bread, certain kinds of food play key roles during Turkish rites, generally upholding traditions. This paper highlights the place of food in the rites of passage in Turkish culture. © The Turkish Online Journal of Educational Technology.
Kilic A.M.,Balkesir University
Turkish Journal of Earth Sciences | Year: 2016
The Hallstatt-type limestones in the Central Pontides yield abundant conodonts of the genus Gladigondolella ranging throughout the entire studied sequence and indicating Anisian to Early Carnian ages. Gladigondolella okayi n. sp. is described. © TÜBİTAK.
Buyukkahraman G.,Balkesir University
Arabian Journal of Geosciences | Year: 2016
In this study, petrological characteristics of the Early-Middle Eocene Bozaniç volcanic rocks resulting from the closure of the Neotethys Ocean in the Central Sakarya region and geodynamic evolution of the Eocene magmatism in the region were investigated. Although previous researchers attained insightful findings about the geodynamic evolution of the region, the age of the post-collisional volcanism, petrological characteristics, and source of the magma remain uncertain. Therefore, volcanic rocks outcropping nearby Sarıcakaya-Mihalgazi (Eskişehir) are investigated in this study. For that purpose, geological map of the study area was drawn and mineralogical, petrographic, geochemical, and isotopic analyses were performed on rock samples collected from different locations. Bozaniç volcanic rocks outcropping as lavas and pyroclastics (agglomerate, lapillistone, and tuff) seem to be derived from four separate volcanic chimneys located in the study area and their composition are typically andesite. According to petrographic data, hypocrystalline porphyritic and microlitic porphyritic are the dominant textures of the rocks. Plagioclase, amphibole, clinopyroxene, and biotite are the main minerals, while sanidine, opaque minerals, chalcedony, calcite, and chlorite can also be observed in small amounts. Geochemically, they show calc-alkaline characteristics and contain medium-high K. Fractional crystallization is the most important process in the development of the rocks. Bozaniç volcanic rocks were derived from a lithospheric mantle source that developed in the active continental margin. According to 40Ar/39Ar age spectra of the samples, the ranges of 48.13 ± 0.15–48.78 ± 0.23 Ma plateau ages were obtained. (87Sr/86Sr)i ratios of the rocks range between 0.705404 and 0.705502, while (143Nd/144Nd)i ratios range between 0.512570 and 0.512581. Consequently, the age data obtained in this study show that the formation time of the first products of the post-collisional volcanism be as early as the Early Eocene and the presence of those is important in terms of the elucidation of geodynamic evolution of the region. © 2016, Saudi Society for Geosciences.
Erturk M.,Balkesir University
Energy | Year: 2016
This article is about the effects of insulation thickness on the life cycle costs of steel pipes inside the pit (channel, duct) or above-ground structures with different diameters and sensitivity to economic parameters. The heating degree-day and life cycle cost procedures are used for the optimization and sensitivity analyses. For Afyon province in Turkey the fuels are coal, natural gas and fuel-oil. The insulation materials are rock wool, EPS and XPS. The results show that consideration of all the physical and economic conditions appear with the optimum insulation thickness that varies from 5 cm to 16 cm. Both lifetime and unit cost of insulation are sensitive to the insulation thickness. Additionally, the increased discount rate and cost per unit volume of insulation material lowers the optimum insulation thickness. In conclusion, it is expected that this study will provide a guide for engineers, where insulation is used for large diameter pipes. © 2016 Elsevier Ltd