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Öğe Can Resorbable Fixation Screws Replace Titanium Fixation Screws? A Nano-Indentation Study(W B Saunders Co-Elsevier Inc, 2016) Altan, Ahmet; Damlar, Ibrahim; Sahin, OsmanPurpose: The aim of this study was to compare the nano-hardness and elastic modulus of titanium and resorbable screws and determine whether resorbable screws could completely replace titanium screws. Materials and Methods: The mechanical properties (nano-hardness and decreased elastic modulus) of TriMed titanium, resorbable Inion CPS, and Synthes RapidSorb samples were measured using a nanoindentation technique. In this study, a Hysitron TriboIndenter TI 950 with a resolution less than 1 nN and a displacement resolution of 0.04 nm was used for the nano-indentation tests. The unloading segments of the nano-indentation curveswere analyzed using the method of Oliver and Pharr (J Mater Res 7: 1564, 1992). Results: Statistical analysis showed that the values of the elastic modulus and nano-hardness of the TriMed titanium screws were significantly higher than those of the resorbable Inion CPS and Synthes RapidSorb screws (P < .05). A statistical difference was not observed between the values of the elastic modulus and the nano-hardness of the Inion CPS and Synthes RapidSorb screws (P > .05). Conclusions: In this study, the resorbable screws were found to be soft and flexible compared with the titanium screw. According to the results of this nano-indentation study, resorbable and titanium screws cannot be used interchangeably. (C) 2016 American Association of Oral and Maxillofacial SurgeonsÖğe Effect of Carbon Content on the Mechanical Properties of Medium Carbon Steels(Walter De Gruyter Gmbh, 2010) Calik, Adnan; Duzgun, Akin; Sahin, Osman; Ucar, NazimThe mechanical properties of medium-carbon steels with a carbon content ranging from 0.30 to 0.55 wt.% were investigated by tensile and microhardness tests at room temperature. It was observed that the higher carbon content results in an increase in yield stress and ultimate tensile stress, while the elongation remains essentially constant. The results were explained by the hindering of dislocation motion associated with solid solution hardening.Öğe Effect of pH on the structural, optical and nanomechanical properties of CdS thin films grown by chemical bath deposition(Elsevier Sci Ltd, 2016) Yucel, Ersin; Sahin, OsmanCdS nano-structured thin films were prepared on glass substrates with chemical bath deposition technique for different pH values. The effects of pH and annealing on the structural, optical and nanomechanical properties of CdS films were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis spectrophotometer and nanoindentation techniques. The results of XRD analysis and SEM investigation reveal that both different pH values of the bath solution and annealing affect the crystal structure and the surface morphology of the films markedly. Also, the results of the optical absorption show that the E-g values of the films decrease with increasing pH values. In this kind of study the mechanical properties of the CdS thin films determined using nanoindentation tests are being reported here for the first time. Nanoindentation experimental results show that nanohardness and elastic modulus values exhibit a peak load dependence. Our results reveal that, the annealing of CdS films at 300 degrees C results in slow and normal grain coarsening. The slow grain growth also influences the lattice strain (microstrain) which effects nanohardness and elastic modulus. The results also indicate that there is a direct dependence of the physical and optical properties of the CdS films on pH and annealing process. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.Öğe Hydrothermal preparation and electrochemical properties of Gd3+ and Bi3+, Sm3+, La3+, and Nd3+ codoped ceria-based electrolytes for intermediate temperature-solid oxide fuel cell(Elsevier, 2010) Dikmen, Sibel; Aslanbay, Hasan; Dikmen, Erdal; Sahin, OsmanThe structure, the thermal expansion coefficient, electrical conductivities of Ce0.8Gd0.2-xMxO2-delta (for M: Bi, x=0-0.1, and for M: Sm, La, and Nd, x=0.02) solid solutions, prepared for the first time hydrothermally, are investigated. The uniformly small particle size (28-59 nm) of the materials allows sintering of the samples into highly dense ceramic pellets at 1300-1400 degrees C. The maximum conductivity, sigma(700 degrees C) around 4.46 x 10(-2) S cm(-1) with E-a =0.52eV, is found at x = 0.1 for Bi-co-doping. Among various metal-co-dopings, for x = 0.02, the maximum conductivity, sigma(700 degrees C) around 2.88 x 10(-2) S cm(-1) with E-a = 0.67 eV, is found for Sm-co-doping. The electrolytic domain boundary (EDB) of Ce0.8Gd0.1Bi0.1O2-delta is found to be 1.2 x 10(-19) atm, which is relatively lower than that of the singly doped samples. The thermal expansion coefficients, determined from high-temperature X-ray data are 11.6 x 10(-6) K-1 for the CeO2, 12.1 x 10(-6) K-1 for Ce0.8Gd0.2O2-delta, and increase with co-doping to 14.2 x 10(-6) K-1 for Ce0.8Gd0.18Bi0.20O2-delta. The maximum power densities for the single cell based on the codoped samples are higher than that of the singly doped sample. These results suggest that co-doping can further improve the electrical performance of ceria-based electrolytes. (C) 2009 Elsevier B.V. All rights reserved.Öğe Particle formation and agglomeration of an alumina-zirconia powder synthesized an supercritical CO2 method(Elsevier Sci Ltd, 2012) Gocmez, Hasan; Tuncer, Mustafa; Uzulmez, Ismail; Sahin, OsmanAlumina - 20 vol% zirconia doped with 2 mol% yttria composites were prepared by a supercritical CO2 method. The powder characteristics were examined through control of the supercritical conditions; temperature and pressure. The agglomeration degrees (N) for powders were changed from 1.2 and 5.4. As the value N become smaller or close to unity, powder agglomerates tend to approach their primary powder size. The sintered sample had hardness of 12.5 GPa. SEM and TEM characterization were used to characterize the microstructure and morphology of the prepared powders. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
