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Öğe The use of CeO-TiO2 nanocomposites as enzyme immobilization platforms in electrochemical sensors(Türkiye Kimya Derneği, 2017) Uzunoğlu, AytekinThe use of metal oxide-based nanoparticles plays a key role in the development of electrochemical sensors with superior properties such as high sensitivity, wide linear range, low limit of detection, and extended storage stability. In this work, we aimed to synthesize CeO2-TiO2mixed metal oxide nanoparticles which were used as substrate materials for the immobilization of bio-recognition element for the construction of enzyme-based electrochemical sensors. For this purpose, in the first part of the study, CeO2-TiO2 nanoparticles were prepared via a low-temperature co-precipitation method and characterized using X-ray Diffraction (XRD), N2-adsorption, and Transmission Electron Microscopy (TEM) methods. The XRD results confirmed the successful synthesis of CeO2-TiO mixed metal oxide nanoparticles with the average crystallite size of 8.51 nm. The calculated crystallite size value was compatible with that obtained from the TEM images. The N2 adsorption results revealed a large surface area of 78.6 cm2 g-1 which is essential for the construction of electrochemical sensors with improved performance. The electrochemical sensors were developed by the deposition of nanoparticles on the surface of a Pt electrode, followed by the immobilization of lactate oxide enzyme. The electrochemical performance of the sensors was evaluated by cyclic voltammetry (CV) and chronoamperometry methods. The constructed sensors showed a sensitivity of 0.085 ± 0.008 µA µM-1 cm-2 (n=5) with a high reproducibility (RSD % = 1.3) and a wide linear range (0.02-0.6 mM). In addition, the detection limit towards lactate was found be 5.9 µM. The results indicated that the use of CeO-TiO2 nanoparticles used as a modifier on the surface of the Pt electrode enabled the construction of electrochemical lactate sensors with high sensitivityÖğe Transfer of project development training to vocational high school students to three axis Mini CNC Router design: an applied study(Ahmet Akçay, 2017-12-31) Yıldırım, Ferdi; Doğan, Onur; Elen, Levent; Çiçek, BünyaminThe aim of this study is to determine the success of the project development and rehabilitation courses given to university students on their students. In this direction, theoretical and practical training was given to the students on the theoretical calculations of machine construction, machine design and manufacturing, assembly stages and system analysis and study. As a result of this training, students were asked to design and manufacture a three-axis mini CNC router. During the design and manufacturing process, the necessary technical support was provided to the students where they had problems. As a result of the study, it has been seen that the students have successfully transferred the theoretical knowledge they have received to CNC router design and manufacturing. After the manufacturing process is completed, a sample is processed and the functionality of the mini CNC router machine is tested and a successful result is obtained. In addition, student achievement was statistically analyzed with a written examination including CNC machine design, construction principles and manufacturing operations. The results and analyzes obtained when the exams are evaluated; shows that the success rate of the exam is 77.75% in the light of the theoretical and practical information that the students have taken during the project period.Öğe Microstructural and mechanical characterization of 9Cr-1Mo-1W weld metal(Hitit University, 2018-09-01) Salur, Emin; Acarer, Mustafa; Kabakçı, Fikret; Keskinkılıç, Selçuk; Kumdalı Acar, Filiz; Çiçek, BünyaminThis paper presents microstructural and mechanical characterization of E911 welds metal. The types and transformations of the phases and microstructures of all-weld metal have been investigated through scanning electron microscopy, optical microscope, x-ray diffraction analysis. The elemental analysis and mechanical tests of the weld metal was determined by x-ray fluorescence, hardness measurements, and tensile tests respectively. This study will contribute the understanding of microstructural progression, microstructure characterization and mechanical properties of E911 steel after the post-weld heat treatment (PWHT).Öğe The effect of welding positions on the weldability of X20CrMoV11-1 steels(2018-01-01) Çiçek, Bünyamin; Gündoğdu İş, Emine; Gümüş, Emre; Topuz, PolatIn the study, mechanical properties of martensitic steel X20CrMoV11-1 was investigated after being welded using Tungsten Inert Gas (GTAW) welding method at different weld positions (PC and PJ-EN 6947). The X20CrMoV11-1 steels have been widely used in thermal power plant applications in combustion chambers and other high-temperature parts. These materials experience extremely high internal pressure at the service conditions. WCrMoV12 Si was used as the filler metal in the welding. The GTAW welding process was conducted in a controlled manner and all the parameters used during the process was monitored. The post welding heat treatment was applied in order to eliminate the variations in the hardness of the welded materials. The samples were characterized using tensile, bending, hardness, and notch impact tests. Macro photographs were taken from the samples to observe the transition areas. The results indicated that the mechanical properties obtained from the samples welded in PC position were higher than those obtained from PJ position.
