Browsing by Author "Ozdemir, I"

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    Association between severity of LUTS, erectile dysfunction and components of metabolic syndrome
    Demir, O; Akgul, K; Akar, Z; Cakmak, O; Ozdemir, I; Bolukbasi, A; Can, E; Gumus, B
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    Association between premature ejaculation and LUTS severity
    Demir, O; Akgiil, K; Akar, Z; Cakmak, O; Ozdemir, I; Bolukbasi, A; Can, E; Gumus, B
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    Wear behavior of flame-sprayed Al2O3-TiO2 coatings on plain carbon steel substrates
    Kusogu, IM; Celik, E; Cetinel, H; Ozdemir, I; Demirkurt, O; Onel, K
    In this study, Al2O3-TiO2 powders were sprayed using a flame-spray technique after a NiCrMo bond layer was deposited on plain carbon steel substrate. The produced layers were characterized by X-ray diffraction (XRD), optical microscope, scanning electron microscope (SEM) including energy-dispersive spectroscopy (EDS), surface roughness and microhardness tester. Friction and wear behaviour of the coatings were also evaluated in the present study. The Al2O3-TiO2 coatings were subjected to sliding wear against AISI 303 stainless steel counter body under dry and acidic environments. A pin-on-plate type apparatus was used with normal loads in the range of 49-129 N. Wear resistance of the coatings in acid environment is better than that in dry conditions. (c) 2005 Elsevier B.V. All rights reserved.
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    Heat Treatment Effects on Mechanical Properties of Atmospheric Plasma Sprayed FexB Coatings on Al Substrate
    Culha, O; Sahin, S; Ozdemir, I; Toparli, M
    In this work, we draw attention to determination of heat-treatment effects on mechanical properties of atmospheric plasma sprayed (APS) FexB coatings on aluminum substrates by micro-indentation technique. With this regard, iron boride powders of Fe-18.8B-0.2C-0.5Si-0.8Al (wt.%) were deposited onto Al substrates by APS in order to improve the mechanical properties of Al surface. As-sprayed coatings are composed of mainly FexB and iron matrix supersaturated with boron owing to the rapid solidification of molten droplets flattened on a substrate. It was observed that APS coatings exhibited characteristic wavy layered structure having porosity, inclusions, and semi-melted particles. The postfurnace treatment of APS coatings was carried out at temperatures ranged from 450 to 550 degrees C in an argon atmosphere. The post-treatment applied for APS deposits led to increase in hardness of 40% without showing cracks. Furthermore, micro-mechanical properties of FexB coatings were examined by Shimadzu Dynamic Ultra-Microhardness Tester for estimating Young's modulus and hardness due to load-unload sensing analysis by applying different loads such as 160, 320, and 640 mN to determine load and indentation depth dependency of APS FexB on Al substrate for each samples, in details.
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    Modelled and measured residual stresses in a bimaterial joint
    Sahin, S; Toparli, M; Ozdemir, I; Sasaki, S
    A finite element technique has been used to predict residual and thermal stresses due to welding. For this purpose, a steel-brass material couple was chosen and thin plates of the materials were hard brazed. The finite element study was carried out using two-dimensional models. After the temperature distributions as a result of welding were calculated, thermal and residual stress values obtained. Thermo-elasto-plastic formulations using a von-Mises yield criterion with linear isotropic-hardening were employed. For this deformation, the initial stress method was used and the kinematical Bauschinger effect was considered. The authors prepared all calculation programs using FORTRAN 77. To obtain residual stresses that occur during the welding, the hole-drilling strain-gage method was chosen and conducted in accordance with the ASTM Standard E 837-99. The agreement between the calculated results and the experimental data shows that the finite element analysis method is reliable. (C) 2002 Elsevier Science B.V. All rights reserved.
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    Association between severity of lower urinary tract symptoms, erectile dysfunction and metabolic syndrome
    Demir, O; Akgul, K; Akar, Z; Cakmak, O; Ozdemir, I; Bolukbasi, A; Can, E; Gumus, BH
    Introduction. The purpose of this study was to investigate the association between severity of lower urinary tract symptoms (LUTS), erectile dysfunction (ED) and metabolic syndrome. Methods. Our study population included a consecutive series of 190 patients with LUTS (International Prostate Symptom Score-IPSS 7) with or without manifestations of the metabolic syndrome. The diagnoses of diabetes mellitus and hypertension were obtained from the patient's medical history. Data on blood pressure, waist measure, body height and weight were collected and body mass index were calculated. Patients were assessed based on the International Index of Erectile Function (IIEF) for ED and IPSS and IPSS-Quality of Life for LUTS. Blood samples were drawn from fasting patients to determine, fasting blood glucose (FBG), triglycerides, HDL-cholesterol and serum total testosterone levels. Results. In severe LUTS patient group, IIEF erectile function domain scores were significantly lower than moderate LUTS patient group (p0.05). Multiple logistic regression analysis confirmed that presence of ED was the most predictor of severe LUTS. The prevalence of metabolic syndrome was higher in patients with severe LUTS (26%vs. 46%, p=0.009). The severe form of the LUTS was significantly correlated with waist circumference 102cm (p0.05), blood pressure 130/85mmHg (p0.05) and FBG 110mg/dl (p0.01). Conclusion. Obesity, high plasma level of FBG and hypertension constitute risk factors for the development of severe LUTS. Metabolic syndrome may play a key role in the pathogenesis in both ED and LUTS. Presence of ED is the most predictor of severe LUTS.
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    Effect of sintering on mechanical properties of cold sprayed thermal barrier coatings
    Karaoglanli, AC; Turk, A; Ozdemir, I
    In this study, thermal barrier coatings were deposited on nickel-based super-alloy with CoNiCrAlY bond and yttria partially stabilised zirconia top coats, using cold gas dynamic spraying and atmospheric plasma spraying techniques, respectively. High temperature oxidation behaviour and sintering effect on the mechanical properties of the coatings were studied. The main objective of this work is to explain the alteration in coating structure depending on temperature, and the mechanisms that lead to alterations in mechanical properties such as Young's modulus and hardness. Structural examination after oxidation revealed a decrease in porosity content and crack healing on ceramic top coatings resulting from sintering effect.