Browsing by Author "Durmus H."
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Item Weldability of AL99-SiC Composites by CO2 laser welding(SAGE Publications Ltd, 2009) Durmus H.; Meric C.In this study, Al99ĝ€"SiC composites were produced using PM method. In the composites produced, the reinforcement rates of SiC were 0, 5, 10, and 20 (%wt). The matrix Al 99 powders were mechanically mixed with SiC particulates. These powders were compacted at room temperature at 500 MPa for 5 - 10 - 60 mm specimens and followed by sintering at 600 and 620°C for 1 h. Composite specimens were joined by CO2 laser welding method. Rofinĝ€"Sinar SM2000 machine was used for the welding process. The microstructure of melted region was investigated by optical, scanning, and X-ray microchemical analysis techniques. The hardness test, tensile test, and three-point bend test results were presented. The effect to CO2 laser welding method at different reinforcement rates and different sintering temperatures in Al 99 powder was investigated. Because of the lower thermal conductivity of Al99ĝ€"SiC composites, melting zone is wide. It was observed that 0.5 m/min laser welding velocity was suitable for composites with low SiC rate (0% and 5% SiC), and with increasing SiC (10 and 20%), laser welding velocity of 0.3 m/min was suitable. © SAGE Publications 2009.Item The effect of the retrogression process on the wear behaviour of a 7075 aluminium alloy(Carl Hanser Verlag, 2012) Durmus H.; Uzun R.O.; Şahin S.; Yüksel N.Retrogression and re-aging (RRA) process are applied in an attempt to enhance mechanical properties and corrosion resistance of 7075 aluminium alloys. In this study, retrogression and re-aging process have been applied to a 7075 aluminium alloy at 170 °C for 5, 40, 80 min and wear resistance of RRA applied samples have been investigated by ball-on-disc wear test apparatus. Sliding distance has been chosen as 300 meters. Re-aging procedure has been carried out at 125 °C for 10, 20 and 30 hours. Minimum wear loss has been obtained by retrogression for 40 min and aging for 30 hours. © Carl Hanser Veriag, München.Item Mechanical properties of dissimilar and similar cold metal transfer welded galvanized steel 1314 and aluminum aa1050(Carl Hanser Verlag, 2014) Irizalp A.O.; Durmus H.; Yüksel N.; Turkmen I.; Uzun O.This study aims to investigate the weldability of 1050 aluminum alloy (AA1050) and galvanized 1314 steel by the cold metal transfer (CMT) pro-cedur, comparing it with respective welding of similar aluminum sheets. Mechanical properties of welded specimens were determined by tensile testing and hardness measurements. The study was completed by microstructural analysis. The results showed that CMT welding can be applied successfully to join aluminum and steel. © Carl Hanser Verlag GmbH & Co.Item Effect of annealing temperatures on the crystallization and photocatalytic activity of micro-nanoporous TiO2 films produced by electrochemical anodization(Turkish Chemical Society, 2018) Yurddaskal M.; Yurddaskal M.; Dikici T.; Durmus H.In this study, micro-nanoporous TiO2 films were prepared by electrochemical anodization of titanium (Gr-2) in an aqueous solution containing 0.5 wt. % HF solution at a constant potential of 30 V and then annealed in ambient air at 500, 600, 700 and 800 °C for 2 h to obtain crystalline structures. The crystalline phase and surface morphology of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The photocatalytic performances of the samples were evaluated by the photocatalytic degradation of aqueous methylene blue (MB) solutions under UV light illumination for different periods. XRD results indicated that at annealing temperatures higher than 600°C, anatase started to transform into rutile. Increasing annealing temperatures resulted in reduced micro-nanopores diameter and increased wall thickness. At 800°C, the structure completely disappeared. The results demonstrated that changes in both the crystalline structure and surface morphology have a strong influence on the photoactivity of the nanostructured TiO2 films. © 2018, Turkish Chemical Society. All rights reserved.Item A database for screening and registering late onset Pompe disease in Turkey(Elsevier Ltd, 2018) Gokyigit M.C.; Ekmekci H.; Durmus H.; Karlı N.; Koseoglu E.; Aysal F.; Kotan D.; Ali A.; Koytak P.K.; Karasoy H.; Yaman A.; Sengun İ.S.; Sayin R.; Tiftikcioglu B.I.; Soysal A.; Tutkavul K.; Bayrak A.O.; Kısabay A.; Elci M.A.; Yayla V.; Yılmaz İ.A.; Ozdamar S.E.; Erdogan C.; Tasdemir N.; Serdaroglu Oflazer P.; Deymeer F.; Parman Y.; Kendirci M.; Sayan S.; Celebi L.G.; Uluç K.; Tanrıdağ T.; Yuceyar N.; Ekmekci O.; Colakoglu B.D.; Ozturk S.; Tireli H.; Selcuki D.; Neyal A.M.; Kayran Y.; Aluclu M.U.; Koyuncuoglu H.R.; Tokucoglu F.; Secil Y.; Guney F.; Gozke E.; Balaban H.; Akalın M.A.; Koc A.F.; Mulayim S.; Turgut N.The aim of this study was to search for the frequency of late onset Pompe disease (LOPD) among patients who had a myopathy with unknown diagnosis registered in the pre-diagnostic part of a novel registry for LOPD within a collaborative study of neurologists working throughout Turkey. Included in the study were 350 patients older than 18 years who have a myopathic syndrome without a proven diagnosis by serum creatine kinase (CK) levels, electrodiagnostic studies, and/or muscle pathology, and/or genetic tests for myopathies other than LOPD. Acid alpha glucosidase (GAA) in dried blood spot was measured in each patient at two different university laboratories. LOPD was confirmed by mutation analysis in patients with decreased GAA levels from either both or one of the laboratories. Pre-diagnostic data, recorded by 45 investigators from 32 centers on 350 patients revealed low GAA levels in a total of 21 patients; from both laboratories in 6 and from either one of the laboratories in 15. Among them, genetic testing proved LOPD in 3 of 6 patients and 1 of 15 patients with decreased GAA levels from both or one of the laboratories respectively. Registry was transferred to Turkish Neurological Association after completion of the study for possible future use and development. Our collaborative study enabled collection of a considerable amount of data on the registry in a short time. GAA levels by dried blood spot even from two different laboratories in the same patient may not prove LOPD. LOPD seemed to be rarer in Turkey than in Europe. © 2017 Elsevier B.V.Item Cold metal transfer welding of AA6061 to AA7075: Mechanical properties and corrosion(American Society of Mechanical Engineers (ASME), 2019) Çömez N.; Durmus H.Cold metal transfer (CMT) welding provides many advantages for welding of dissimilar materials and thin sheets with its superior heat input control mechanism. In this study, AA6061 and AA7075 aluminum alloys were joined with CMT welding. The effect of welding parameters on hardness, tensile strength, and corrosion rate was investigated. The Tafel extrapolation method was carried out to determine the corrosion rates of AA6061 and AA7075 base metals and AA6061–AA7075 joints. Increasing heat input was found to be detrimental for both mechanical properties and corrosion resistance. The outcomes showed that CMT welding produces adequate joints of AA6061–AA7075 in terms of mechanical properties and corrosion resistance, favorably with welding parameters that provide low heat input. © 2019 by ASME.Item Effects of ECAP with One Pass Severe Deformation on Microhardness, Texture, and Corrosion Behavior of AA1370 Aluminum Alloy Wire(Pleiades journals, 2021) Youcef Hadj Ali; Zazi N.; Durmus H.; Chopart J.-P.Abstract: In this paper, We investigate the effects of one pass severe deformation, obtained by equal channel angular pressing (ECAP) process, using dies with channel angles of 90° and 120°, on hardness, texture, and corrosion behavior, of AA1370 aluminum alloy wire. A severe deformation, by ECAP process, leads to athinning of several diffraction peaks and an increase of their angular values; modifies the texture of material from pseudo-texture to mix texture; reduces the microhardness; modifies a part of localized corrosion towards generalized one; shifts the corrosion potential to negative values; and increases the values of open circuit potential (OCP). The deformation by ECAP process induces fragmentation of parts of intermetallic particles, and reduction of grains size. The imprisoned air, between the channel wall of the die and the wire, creates microporosities in the deformed samples. © 2020, Pleiades Publishing, Ltd.Item Microstructure and Mechanical Properties of Ni Matrix B4C Reinforced Functionally Graded Composites(International Institute for the Science of Sintering (IISS), 2021) Caligulu U.; Durmus H.; Akkas M.; Sahin B.In this study, microstructure and mechanical properties of nickel matrix B4C reinforced functionally graded composites produced by powder metallurgy method were investigated. Samples with Ni+5% B4C, Ni +10% B4C, Ni+ 15% B4C and Ni+ 20% B4C compositions were sintered at 900 and 1050oC for 60 minutes. Microhardness and wear tests along with optical microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) and X-ray diffraction (XRD) analyses were carried out to determine the mechanical properties, microstructure and phase composition of the samples. The results indicated that hardness and wear resistance increased with increases of B4C amount in nickel matrix. © 2021 Authors. Published by association for ETRAN Society.Item Effects of Al2O3 Particles on Corrosion Behavior and Microstructure of Al–Al2O3 Composites and Texture of Aluminum Matrix(Pleiades Publishing, 2024) Dehrib S.; Zazi N.; Durmus H.Abstract: In this paper, we studied the influence of alumina particles addition, 5, 10, and 15 wt %, on the microstructure after elaboration of Al–Al2O3 MMC composite, morphology and kinetic of corrosion, hardness, texture evolution of aluminum matrix. The results show distribution of alumina particles in shape of petal-like phase in some zones, in form of flack in another region for sample with 5% addition alumina, and in mixture between truncated petal-like phase and flake form particles for the sample with 10% addition of alumina, of flake in zone 1 one and a mixture of petal-like phase and flake in zone 2 for the sample with 15% addition of Al2O3, the samples with 5 and 10% Al2O3 were undergo generalized corrosion almost in the all surfaces, but for the sample with 15% addition of was undergo the corrosion which don’t tends to generalized corrosion. The corrosion resistance increase when the Al2O3 addition increases. The texture of aluminum changes slightly when the alumina powders are added to aluminum. The hardness change when alumina powders are added to aluminum. © Pleiades Publishing, Ltd. 2024.Item Push and Pull Factors of Why Medical Students Want to Leave Türkiye: A Countrywide Multicenter Study(Routledge, 2024) Eser E.; Cil E.; Sen Gundogan N.E.; Col M.; Yildirim Ozturk E.N.; Thomas D.T.; Sunter A.T.; Arslan H.N.; Citil R.; Onder Y.; Picakciefe M.; Dede B.; Demirel C.; Aydin N.; Caglayan C.; Aker A.A.; Borlu A.; Durmus H.; Can G.; Siddikoglu E.; Sumer E.H.; Uygun T.; Alkoy S.; Aktas Aycan K.; Koruk İ.; Kuzan R.; Demir L.S.; Hacilar E.; Sari H.; Kilinc Z.; Onal O.; Dogan E.; Emek M.; Terzioglu R.; Yapici G.; Erdal D.; Eser S.; Ayhan Akman E.; Kosan Z.; Yilmaz S.; Ayoglu F.N.; Acikgoz B.; Musal B.; Suner A.F.; Erdogan A.; Cilburunoglu İ.; Saygun M.; Daymaz D.; Arslantas D.; Onsuz M.F.; Beyhun N.E.; Ustundag M.G.; Ekuklu G.; Ozder Tas F.; Abacigil F.; Oncu S.; Hıdıroğlu S.; Ozaydin A.N.; Pirincci E.; Bulut I.; Tozun M.; Eskiocak M.; Gunel P.; Torun S.D.; Yavuz M.; Hasde M.; Camur D.; Gunes G.; Kurt B.; Guler Baysoy N.; Bakirci N.; Demir F.; Catak B.; Ozyurda F.; Turan M.Phenomenon: Physician immigration from other countries is increasing as developed countries continue to be desirable destinations for physicians; however, the determinants of Turkish physicians’ migration decisions are still unclear. Despite its wide coverage in the media and among physicians in Türkiye, and being the subject of much debate, there is insufficient data to justify this attention. With this study, we aimed to investigate the tendency of senior medical students in Türkiye to pursue their professional careers abroad and its related factors. Approach: This cross-sectional study involved 9881 senior medical students from 39 different medical schools in Türkiye in 2022. Besides participants’ migration decision, we evaluated the push and pull factors related to working, social environment and lifestyle in Türkiye and abroad, medical school education inadequacy, and personal insufficiencies, as well as the socioeconomic variables that may affect the decision to migrate abroad. The analyses were carried out with a participation rate of at least 50%. Findings: Of the medical students, 70.7% had emigration intentions. Approximately 60% of those want to stay abroad permanently, and 61.5% of them took initiatives such as learning a foreign language abroad (54.5%) and taking relevant exams (18.9%). Those who wanted to work in the field of Research & Development were 1.37 (95% CI: 1.22–1.54) times more likely to emigrate. The push factor that was related to emigration intention was the “working conditions in the country” (OR: 1.89, 95% CI: 1.56–2.28) whereas the “social environment/lifestyle abroad” was the mere pull factor for the tendency of emigration (OR: 1.73, 95% CI: 1.45–2.06). In addition, the quality problem in medical schools also had a significant impact on students’ decisions (OR: 2.20, 95% CI: 1.83–2.65). Insights: Although the percentage of those who want to emigrate “definitely” was at the same level as in the other developing countries, the tendency to migrate “permanently” was higher in Türkiye. Improving working conditions in the country and increasing the quality of medical faculties seem vital in preventing the migration of physicians. © 2023 Taylor & Francis Group, LLC.Item Effects on Mechanical and Physical Properties of Ta Element Addition to Ti-6Al-7Nb Alloy(Springer, 2025) Caligulu U.; Durmus H.; Kejanli H.; Keskinkilic A.R.; Balci E.Ti and its alloys play a leading role in biomedical applications within the field of materials science. In this study, different amounts of Ta were added to the TiAlNb alloy. Various analyses were carried out to determine the physical and chemical properties of the produced samples. DSC (differential scanning calorimetry), and XRD (X-ray diffraction) analyses were conducted to determine the phase transformations and crystal structure of the alloys, respectively. SEM-EDX (scanning electron microscopy) and OM (optical microscopy) images were taken to analyze the chemical structure of the samples and to examine their microstructures in more detail. Microhardness and wear resistance tests were performed to determine some mechanical properties of the produced samples. It was observed that increasing the tantalum content increased both hardness and wear resistance. These findings suggest that the addition of tantalum to the Ti-6Al-7Nb alloy could be an effective strategy to improve biomaterial performance. © The Minerals, Metals & Materials Society 2024.