Browsing by Author "Kaya, N"

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    The serum zinc and copper values of the Morkaraman and Tuj sheep grown up in the pasture conditions in and around Kars
    Kaya, N; Utlu, N; Uyanik, BS; Özcan, A
    This study was performed on 100 sheep, of which SO were Morkaraman and SO were Tuj, grown up in the pasture conditions in and around Kars. The serum zinc and copper values of the animals were analysed with Atomic Absorbtion Spectrophotometre. The serum zinc and copper values were respectively determined as; 40.56 +/- 5.6 mu g/dl, 80.10 +/- 7.49 mu g/dl in Morkaramans and, 38.72 +/- 5.32 mu g/dl, 75.04 +/- 6.58 mu g/dl in Tujs. There were no significant differences between the value of zinc and copper statistically.
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    Modification of surface morphology of UHMWPE for biomedical implants
    Oztarhan, A; Urkac, ES; Kaya, N; Yenigul, M; Tihminlioglu, F; Ezdesir, A; Zimmerman, R; Budak, S; Muntele, C; Chhay, B; Ila, D; Oks, E; Nikolaev, A; Tek, Z; Eltem, R
    Ultra High Molecular Weight Polyethylene (UHMWPE) samples were implanted with metal and metal-gas hybrid ions (Ag, Ag+N, C+H, C+H+Ar, Ti+O) by using improved MEVVA Ion implantation technique [1,2]. An extraction voltage of 30 kV and influence of 1017 ions/cm2 were attempted in this experiment. to change their surface morphologies in order to understand the effect of ion implantation on the surface properties of UHMWPEs. Characterizations of the implanted samples with RBS, ATR - FTIR, spectra were compared with the un-implanted ones. Implanted and unimplanted samples were also thermally characterized by TGA and DSC. It was generally observed that C-H bond concentration seemed to be decreasing with ion implantation and the results indicated that the chain structure of UHMWPE were changed and crosslink density and polymer crystallinity were increased compared to unimplanted ones resulting in increased hardness. It was also observed that nano size cracks (approx. 10nm) were significantly disappeared after Ag implantation, which also has an improved antibacterial effect. Contact angle measurements showed that wettability of samples increased with ion implantation. Results showed that metal and metal+gas hybrid ion implantation could be an effective way to improve the surface properties of UHMWPE to be used in hip and knee prosthesis.
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    Polymeric thermal analysis of C+H and C+H+Ar ion implanted UHMWPE samples
    Kaya, N; Oztarhan, AM; Urkac, ES; Ila, D; Budak, S; Oks, E; Nikolaev, A; Ezdesir, A; Tihminlioglu, F; Tek, Z; Cetiner, S; Muntele, C
    Chemical surface characterization of C + H hybrid ion implanted UHMWPE samples were carried out using DSC (differential scanning calorimeter) and TGA (thermal gravimetric analysis) techniques. Samples were implanted with a fluence of 10(17) ion/cm(2) and an extraction voltage of 30 kV. The study of TGA and DSC curves showed that: (1) Polymeric decomposition temperature increased, (2) T-m, Delta C-p and Delta H-m values changed while Delta C-p and Delta H-m increased. T-g value could not be measured, because of some experimental limitations. However, the increase in Delta H-m values showed that T-g values increased, (3) the branch density which indicated the increase in number of cross-link (M-c) decreased in ion implanted samples and (4) increase in Delta H-m values indicated increase in crystallinity of implanted surface of UHMWPE samples. Published by Elsevier B.V.
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    Thermal characterization of Ag and Ag plus N ion implanted ultra-high molecular weight polyethylene (UHMWPE)
    Urkac, ES; Oztarhan, A; Tihminlioglu, F; Kaya, N; Ila, D; Muntele, C; Budak, S; Oks, E; Nikolaev, A; Ezdesir, A; Tek, Z
    Most of total hip joints are composed of ultra-high molecular weight polyethylene (UHMWPE). However, as ultra-high molecular weight polyethylene is too stable in a body, wear debris may accumulate and cause biological response such as bone absorption and loosening of prosthesis. In this study, ultra-high molecular weight polyethylene samples were Ag and Ag + N hybrid ion implanted by using MEVVA ion implantation technique to improve its surface properties. Samples were implanted with a fluence of 10(17) ion/cm(2) and extraction voltage of 30 kV. Implanted and unimplanted samples were investigated by thermo-gravimetry analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), optical microscopy (OM) and contact Angle measurement. Thermal characterization results showed that the ion bombardment induced an increase in the % crystallinity, onset and termination degradation temperatures of UHMWPE. (c) 2007 Elsevier B.V. All rights reserved.
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    Investigation of surface-modified EBM printed Ti-6Al-4V alloys for biomedical applications
    Demirci, S; Dikici, T; Tünçay, MM; Dalmis, R; Kaya, N; Kanbur, K; Sargin, F; Güllüoglu, AN
    This work aimed to comprehensively assess the influence of various surface modifications on the formation of apatite ability for EBM Ti-6Al-4V alloy. Sandblasting (S), acid-etching (E), sandblasting and acid-etching (SE), anodization (NA), micro-arc oxidations in 1 M H2SO4 solution (SM) and 1 M H3PO4 solution (PM) methods were applied to modify electron beam melted (EBM) Ti-6Al-4V surface. The alpha/alpha'-Ti structures and TiO2 phases were detected by XRD. The surface roughness (Ra) values ranged from 0.25 mu m and 2.86 mu m. The wettability of samples was between around 25 degrees and 104 degrees The SM sample possessed the lowest contact angle. In vitro tests were employed in the simulated body fluid (SBF) solution for 28 days. The samples with different surface textures demonstrated bioactive behaviors. In vitro test results showed that apatite layers formed on the surfaces. The SM sample exhibited good apatite formation ability when the Ca/P ratios were considered. The apatite formation for the SM sample might derive from high roughness, low contact angle value, the existence of Ti-OH groups, and anatase and rutile phases. The SM can be implemented to boost bioactivity on EBM Ti-6Al-4V alloys.
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    CALCIOTROPIC HORMONE LEVELS IN FLUOROSED TUJ SHEEP
    Kaya, N; Koçer, B; Devrim, AK
    Twenty Tuj sheep weighing 31 +/- 2 kg were investigated for the effect of chronic fluorosis on their serum parathyroid hormone (PTH) and calcitonin (CT) activity levels. For a period of 9 months, ten of the sheep were exposed to 4 ppm NaF (1.8 ppm F ion) in their drinking water to induce fluorosis. During the study, urinary pH gradually increased from 7.2 to 7.9. In the first 12 weeks, urinary fluoride showed a small increase from 0.9 to 1.2 ppm, but by week 38 at the end of the experiment it had risen to 16 ppm, and the serum PTH levels had decreased (p<0.01), whereas the CT levels had increased (p<0.01) compared to the control group.