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Öğe A Comparative Study on Microstructure Properties of AZ91 Magnesium Alloy with Silicon Addition Using Ceramic Mold(Polish Acad Sciences Inst Physics, 2019) Goren, H. A.; Unal, M.; Koc, E.In this study, comparatively microstructure and hardness properties of AZ91 alloy with the addition of 1.95 wt% silicon were investigated by using ceramic mold. For this purpose, the alloys were provided to solidfy in different rates due to using that mold. Alloys cast into this mold showed rapid cooling behavior due to copper in the base, while cooling rate decreased on the top zone. The results showed that alpha+Mg main matrix phase is present in AZ91 structure, Mg-Al eutectic and Mg17Al12 intermetallic phases extending along grain boundaries were observed in the main matrix as well. As the cooling rate increases, the grain boundaries of Mg17Al12 intermetallic phases were increased. The Mg17Al12 phase at grain boundaries was partially fragmented with the addition of Si. Coarsen Mg2Si phases were also formed with the addition of 1.95 wt% silicon. The hardness values were increased with the increasing of cooling rate and the addition of silicon.Öğe Corrosion Behaviour of as Cast ?-Mg17Al12 Phase in 3.5 wt% NaCl Solution(Polish Acad Sciences Inst Physics, 2019) Koc, E.In this study, corrosion behaviour of beta-Mg17Al12 phase was studied as comparing pure magnesium. The corrosion tests were carried out by potentiodynamic polarisation measurements and immersion tests in 3.5 wt% NaCl solution. Compared to pure Mg, beta-Mg17Al12 phase has 2.7 times and 2.1 times lower corrosion resistance according the potentiodynamic polarization and immersion test results, respectively. Deep corrosion pits were formed on the surface of the beta phase.Öğe Corrosion Behaviour of as Cast ?-Mg17Al12 Phase in 3.5 wt% NaCl Solution (vol 135, pg 881, 2019)(Polish Acad Sciences Inst Physics, 2019) Koc, E.[No abstract available]Öğe The effect of dimethoate on Capoeta capoeta (Guldenstaedt 1773) and the protective effect of ascorbic acid(Parlar Scientific Publications, 2016) Tanriverdi, E.A.; Yilmaz, M.; Koc, E.; Akgul, A.; Ersan, Y.In this study, Dimethoate (DM) (a pesticide)'s histopathological and electrophoretic effects were investigated on Capoeta capoeta (Guldenstaedt 1773) that were captured from Kars creek, and the protective effect of ascorbic acid (AA) (vitamin C) was tested. After allowing time for their adaptations to their new environment, the fish caught from Kars creek were divided into 4 groups (each including 10 fish), and placed in 300-liter tanks in the laboratory. The fish were kept in water containing different solutions: group I in normal water medium, group II in 100 mg/L AA, group III in 2 mg/L DM, and group IV in 100 mg/L AA and 2 mg/L DM. They were kept in these water mediums for 10 days. After this period, blood and tissue samples were taken from the fish for electrophoretic and histopathological studies. Tissue samples were detected in 10% formaldehyde solution and paraffin blocks were prepared by routine histological methods. The samples were cut into sections 3-5 ? thick, all stained according to hematoxylin and eosin staining methods, and they were examined under a microscope. Obtained serum samples were carried out in Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE). When we compared the serum samples with the control group of fish, protein bands in the application of 100 mg/L AA and 2 mg/L DM, thickening in 36 kD band, thinning in 100 kD, 97 kD, 76 kD, 56 kD and 30 kD bands were observed, and the bands of 93 kD, 46 kD, 44 kD and 26 kD were detected as newly-synthesized in SDSPAGE electropherogram. In the histopathological examinations, depending on DM in intestine, liver, and kidney tissues obtained from the group formed by application of DM and AA, degeneration, necrosis, pyknotic nuclei and cell infiltrates were detected. As a result, whereas DM application was found to create toxic effects on Capoeta capoeta, AA was found to have a healing effect. © 2016 by PSP.Öğe Effects of titanium addition on mechanical and corrosion behaviours of AZ91 magnesium alloy(Elsevier Science Sa, 2011) Candan, S.; Unal, M.; Koc, E.; Turen, Y.; Candan, E.The mechanical properties and corrosion behaviour of AZ91 magnesium alloy containing 0.2-0.5 wt.% Ti were investigated in this study. Results demonstrate that the enhancement of the ultimate tensile strength by 18% and yield strength by 47% can be achieved by Ti addition. The corrosion behaviour was evaluated by immersion tests and potentiodynamic polarisation measurements in 3.5% NaCl solution. The results from the immersion tests and potentiodynamic polarisation measurements showed that the corrosion resistance of AZ91 alloy increased progressively with the increase of the Ti content of the alloy. Compared to AZ91 alloy, 0.5Ti addition increased the corrosion resistance by up to 45 fold. The mechanism of property enhancement is ascribed to both the suppression of partially divorced beta-Mg17Al12 eutectics and an increased Al content in alpha-Mg solid solution by Ti addition in AZ91 alloy. (C) 2010 Elsevier B.V. All rights reserved.Öğe Efficiency of ascorbic acid against oxidative stress-induced dimethoate toxicity in fish, Capoeta capoeta [Guldenstaedt, 1773](Triveni Enterprises, 2017) Yilmaz, M.; Kaya, I.; Koc, E.; Tanriverdl, E. A.; Kaya, M. M.; Ersan, Y.Aim: The main objective of the present study was to evaluate the effect of ascorbic acid against oxidative stress-induced by dimethoate in Capoeta capoeta. Methodology: The fish caught in Kars Creek were randomized in four equal groups and acclimatized in separate tanks. The fish were kept in tanks for 10 days as follows: Group I (control) was kept in normal water, Group II, Ill and IV were kept in separate tanks containing 2 mgrdimethoate and 2 mgr dimethoate plus 100 mgr' ascorbic acid and ascorbic acid. The level of total sialic acid, total antioxidant status and total oxidant status in fish serum were analyzed. Results: Total sialic acid level of Group III was found to be lower than the level of Group II (P< 0.05), there were no statistically important differences between these two groups in total antioxidant status and oxidant status. In gills, intensive cartilage degenerations and mononuclear cell infiltrations in group II and III were observed. It was found that toxic effects of dimethoate in group III decreased. Interpretation: Ascorbic acid in fish exposed to dimethoate reduced the level of total sialic acid and degenerations in lamellae of gills, it had no significant effect on the oxidative stress response. [GRAPHICS] .Öğe Improvement of mechanical and corrosion properties of magnesium alloy by lead addition(Elsevier Science Sa, 2009) Candan, S.; Unal, M.; Turkmen, M.; Koc, E.; Turen, Y.; Candan, E.Mechanical properties and corrosion behaviour of AZ91 magnesium alloy containing 0.2-1.0 wt.% Pb were investigated. An enhancement of ultimate tensile strength by 42%, yield strength by 58% and elongation by 20% can be achieved by Pb addition. Corrosion resistance of the AZ91 alloy also increased progressively with increasing Pb content. The mechanism of property enhancement is ascribed to the suppression of intermetallic phases (beta-Mg17Al12 and alpha-Mg+beta eutectic) by Pb addition. (c) 2008 Elsevier B.V. All rights reserved.Öğe Incorporation of B and La oxides into bioactive glass: in vitro studies for bone regeneration applications(Virtual Co Physics Srl, 2024) Badraddin, R.; Koc, E.; Saud, A. N.Bone tissue engineering seeks to regenerate damaged tissues using biocompatible scaffolds that mimic bone minerals. This study focuses on scaffolds based 45S5 bioactive glass (45% SiO2, 24.5% Na2O, 6% P2O5, 24.5% CaO) doped with boron and lanthanum oxides. These scaffolds, produced via conventional melting, form a hydroxyapatite layer, promoting strong bone integration. Result of DTA, XRD, FTIR, SEM, and EDS, showed doping led to crystalline phase identification, silicate network confirmation, and detection of calcium phosphorus deposits. Doping also increased pH, degradation kinetics, and antibacterial activity. These findings suggest that boron and lanthanum-doped 45S5 scaffolds have potential in bone regeneration applications.Öğe Real-world experience of ocrelizumab in MS in the Turkish population: A single-center study(Wiley, 2022) Koc, E.; Saridas, F.; Ceylan, D.; Turan, O.; Ozkaya, G.[No abstract available]
