Yazar "Turkoz, Mustafa B." seçeneğine göre listele
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Öğe Effect of Co/Cu partial replacement on fundamental features of Y-123 ceramics(Springer, 2020) Ozturk, Ozgur; Nefrow, Abdul R. A.; Bulut, Fatih; Ada, Hakan; Turkoz, Mustafa B.; Yildirim, GurcanThis study is liable for the effect of sample production processes including the standard solid-state reaction (SSR) and classical sol-gel (SG) preparation methods on the fundamental characteristic features, namely electrical, superconducting, crystal structure quality, crystallinity, morphological, strength quality of grain boundary couplings, and interaction between the grains of YBa2Cu3-xCoxO7-delta (Y-123) advanced ceramic compounds within the weight ratio intervals x = 0-20%. The main heat treatments are exerted at two main steps: (I) annealing at 950 degrees C for 24 h in air medium conditions and (II) annealing at 500 degrees C during 5 h under the oxygen annealing ambient. The standard measurement methods such as powder X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, temperature-dependent electrical resistance, and Vickers hardness measurements are performed for the characterization of materials. It is found that the samples prepared at SSR route present much more superior characteristic features as compared to those fabricated at SG technique, being one of the most striking points deduced this work. In more detail, every material prepared crystallizes in the orthorhombic symmetry and exhibits the superconducting nature but considerable decrement in the critical transition temperatures. The onset and offset transition temperatures are noted to decrease regularly from 92.96 K (92.28 K) to 90.20 K (83.59 K); and 90.05 K (90.03 K) to 45.97 K (30.49 K) for the materials prepared by the SSR (SG) route. Similarly, the variation in the lattice cell and average grain size parameters confirm that the Co/Cu substitution damages Y-123 superconducting phase. Additionally, the Co/Cu partial replacement mechanism leads to increase significantly the Vickers hardness results. To sum up, the Co/Cu partial substitution (produced by either SSR or SG method) is plowed to improve the fundamental characteristic features for new, novel, and feasible market application areas of Y-123 cuprate ceramics in the universe economy.Öğe Fabrication of mechanically advanced polydopamine decorated hydroxyapatite/polyvinyl alcohol bio-composite for biomedical applications: In-vitro physicochemical and biological evaluation(Elsevier, 2022) Erdem, Umit; Dogan, Deniz; Bozer, Busra M.; Turkoz, Mustafa B.; Yildirim, Gurcan; Metin, Aysegul U.In this study, polydopamine (PDA) coated hydroxyapatite (HA) reinforced polyvinyl alcohol (PVA) films were produced to be used in biomedical applications such as bone tissue regeneration. pDA is coated not only to prevent the agglomeration of HA when encountering interstitial fluids but also to strongly bind the PVA for the interaction between materials so that the mechanical performance becomes more stabilized. pDA was coated on the hydroxyapatite surface using a radical polymerization technique, and the reinforced PVA were produced with pDA-coated HA (pDA-HA/PVA) nanoparticles. Fundamental characteristic properties of pDA-HA/PVA nanocomposite films were examined by morphological/chemical (SEM-EDS), microstructural (XRD, Ft-IR, and Raman), thermodynamic (TGA and TM), mechanical performance (Vickers microhardness) and biological activity analysis (MTT, genotoxicity and antimicrobial efficacy investigations). Physicochemical analysis showed that all the samples studied exhibited homogeneous mineral distributions through the main structures. According to TGA, TMA and hardness tests, the new composite structure possessed higher mechanical properties than neat PVA. Further, pDA-HA/PVA nanocomposites exhibited high antibacterial capacities against Acinetobacter Baumannii (A.Baumannii), Staphylococcus aureus (S. aureus), and Streptococcus mutans (S.mutans). Moreover, the new nanocomposites were noted to present good biocompatibility for fibroblast (L929) cells and to support remarkably MCS cells. All in all, this comprehensive work shows that the thermo-mechanically improved pDA-HA/PVA films will increase the application fields of PVA in biomedical fields especially tooth-bone treatments for coating, filling, or occlusion purposes.Öğe Hydroxyapatite-based nanoparticles as a coating material for the dentine surface: An antibacterial and toxicological effect(Elsevier Sci Ltd, 2020) Erdem, Umit; Dogan, Mustafa; Metin, Aysegul U.; Baglar, Serdar; Turkoz, Mustafa B.; Turk, Mustafa; Nezir, SaffetIn this study, nano sized hydroxyapatite (nHAp) and Ag(I) doped hydroxyapatite (Ag-nHAp) particles were synthesized by the precipitation method and used as a coating material for remineralization on caries-affected dentine samples. Characterization studies of both the synthesized hydroxyapatite-based particles and the coated dentine samples were performed using instrumental techniques such as SEM and FFIR, and then toxicity and antibacterial properties were also evaluated. It was observed that dentine samples were effectively coated by both nHAp and Ag center dot nHAp particles which have no toxic effects. Furthermore, the costing of nano-hydroxyapatite on dentine samples positively contributed to the viability of L929 fibroblast cells and also provided an antibacterial effect against to bacteria such as S. mutants, C. albicans and E. coli bacteria that are most frequently caused caries in the teeth. While all type of bacteria was eliminated by the nHAp coated dentine samples at 24th, Ag-nHAp coated dentine samples removed to all bacteria type at 1st.Öğe La3+ and F- dual-doped multifunctional hydroxyapatite nanoparticles: Synthesis and characterization(Wiley, 2021) Erdem, Umit; Turkoz, Mustafa B.Hydroxyapatite (HA) co-doped with La3+ and F- ions were synthesized by the precipitation method and sintered at 1,100 degrees C for 1 hr. Samples were characterized by the standard experimental methods including the density, X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM) to investigate their microstructure, phase formation, and bonding characteristics in detail. Moreover, the materials produced were identified using the microhardness tests. It was observed that in the most of materials, the hydroxyapatite was found to be the main phase with a minor amount of beta-tricalcium phosphate (beta-TCP). Furthermore, the presence of fluoride and small amount of beta-TCP was verified with all the characteristic FTIR bands of hydroxyapatite for the majority of samples studied. The result in SEM evaluation is that the produced HA powders have less deformed, uniformly distributed, and regularly shaped particles. Here, the material density has changed towards a less dense state with the increasing rate of La doping, but statistically significant difference was not obtained (p, .1942 > .05) with increase of the F doping. A significant difference was obtained the microhardness values between La3+ and F- ions co-doped HA materials and pure HA (p [.0053] < .05). Accordingly, this study confirmed that since the La3+ and F- ions can potentially increase the efficacy of HA. According to the spectral, mechanical, and microstructure analysis result, this material can be as a good candidate product for use as an occluding material for dental application.Öğe Refinement of fundamental characteristic properties with homovalent Er/Y partial replacement of YBa2Cu3O7-y ceramic matrix(Elsevier Science Sa, 2021) Erdem, Umit; Turkoz, Mustafa B.; Yildirim, Gurcan; Zalaoglu, Yusuf; Nezir, SaffetIn the current work, the effect of partial substitution of Er-sites for the Y-sites in the bulk YBa2Cu3O7-y (YBCO) crystal system on the fundamental superconducting, electrical, crystallinity and structural morphology features is examined together with the reasons by means of powder X-ray diffraction (XRD), temperature-dependent electrical resistivity (rho-T), scanning electron microscopy (SEM), electron dispersive X-ray (EDX) investigations and deduced calculation parameters. All the experimental test results show that the erbium impurities are suc-cessfully substituted by the yttrium sites in the bulk Y-123 crystal system, confirmed by sensitively the EDX and rho-T measurement results. Moreover, it is found that all the fundamental characteristic quantities improve with the increment in the Er/Y partial substitution level up to the value of x = 0.03 beyond which the features tend to degrade dramatically. In this respect, the bulk Y1-xErxBa2Cu3O7-y ceramic compound prepared within the molar ratio of x = 0.03 crystallizes in the orthorhombic space group P-4/ mmm with a little distortion due to the refinement in the crystallinity quality, crystallite growth, oxygen ordering degree, scattering mechanism, intra and intergrain boundary couplings, grain alignment distributions and orientations. The XRD results show that the optimum erbium content enables to develop seriously the fundamental crystallographic features (lattice strain, lattice cell constants, crystallite size distribution, dislocation density ratio, oxygen concentrations in the unit cells) of Y-123 crystal structure. However, the excess Er/Y substitution leads to enhance considerably the systematic structural problems and inhomogeneous distribution of strains (formed by the structural defects) in the YBCO crystal structure. Thus, the phase transition from orthorhombic to tetragonal (structural O-T transition) crystal structure is observed. In fact, the XRD result displays that the trivalent Er3+ particles may partially be replaced by the divalent Cu2+ host atoms in the bulk Y-123 crystal structure after the critic substitution level of x = 0.03. The optimum Er concentration causes to form more thermodynamically activated super-electrons in the homogeneous superconducting cluster percentages in the paths due to the induced polaronic effect, and accordingly the intrinsic overdoped nature of Y-123 ceramic system transits into optimally doped state. Similarly, the erbium ions enable to increase the mobile hole carrier concentration and homogeneities in the oxidation state of superconducting grains. Namely, the amplitude of pair wave function (Psi=Psi(0)e(-i phi)) is strength enough to form bipolarons in the polarizable lattices and localize of densities of electronic states (DOS) at Fermi level. SEM investigations picture that the surface morphology view and crystallinity quality develop remarkably with the increment in the erbium content up to the critical dopant level of x = 0.03 where the sample exhibits the best grain alignment orientations, densest and smoothest surface morphology with the combination of lowest porous and largest particle distributions well linked each other. All in all, this comprehensive work based on the analysis of Er/Y partial replacement mechanism along the YBa2Cu3O7- y ceramic matrix may open up a newly/novel and feasible area for the advanced engineering, heavy-industrial technology and large-scale applications of type-II superconducting materials. (C) 2021 Elsevier B.V. All rights reserved.Öğe Resorbable membrane design: In vitro characterization of silver doped-hydroxyapatite-reinforced XG/PEI semi-IPN composite(Elsevier, 2023) Dogan, Deniz; Erdem, Umit; Bozer, Busra M.; Turkoz, Mustafa B.; Yildirim, Gurcan; Metin, Aysegul U.In this study, the production and characterization of silver-doped hydroxyapatite (AgHA) reinforced Xanthan gum (XG) and Polyethyleneimine (PEI) reinforced semi-interpenetrating polymer network (IPN) biocomposite, known to be used as bone cover material for therapeutic purposes in bone tissue, were performed. XG/PEI IPN films containing 2AgHA nanoparticles were produced by simultaneous condensation and ionic gelation. Characteristics of 2AgHA-XG/PEI nanocomposite film were evaluated by structural, morphological (SEM, XRD, FT-IR, TGA, TM, and Raman) and biological activity analysis (degradation, MTT, genotoxicity, and antimicrobial activity) techniques. In the physicochemical characterization, it was determined that 2AgHA nanoparticles were homogeneously dispersed in the XG/PEI-IPN membrane at high concentration and the thermal and mechanical stability of the formed film were high. The nanocomposites showed high antibacterial activity against Acinetobacter Baumannii (A.Baumannii), Staphylococcus aureus (S.aureus), and Streptococcus mutans (S.mutans). L929 exhibited good biocompatibility for fibroblast cells and was determined to support the formation of MCC cells. It was shown that a resorbable 2AgHA-XG/PEI composite material was obtained with a high degradation rate and 64% loss of mass at the end of the 7th day. Physico-chemically developed biocompatible and biodegradable XG-2AgHA/PEI nanocomposite semi-IPN films possessed an important potential for the treatment of defects in bone tissue as an easily applicable bone cover. Besides, it was noted that 2AgHA-XG/PEI biocomposite could increase cell viability, especially in dental-bone treatments for coating, filling, and occlusion.Öğe Silver release of Ag (I) doped hydroxyapatite: In vitro study(Wiley, 2019) Erdem, Umit; Turkoz, Mustafa B.A material is produced by doping of silver (Ag (I)) which has antibacterial property to nano hydroxyapatite (nHAp), to remove the hipersensitivity in the teeth by closing the dentine tubules or dental micro cracks of the teeth and effective against for some bacteria. The doping of Ag (I) can also produces a toxic effect. Ag (I) can be released from the structure as a result of biological, physical and chemical effects and may cause toxicity. Therefore, it is important to determine whether the presence of Ag (I) has a toxic effect. In this study, Ag (I)-doped nHAp was synthesized by precipitation method and tried to determine the release values as a function of time compared to the doping rate by using the ICP-OES. Also, the products we produce in simulated body fluid were kept for retention periods of 4-20 weeks to determine degradation percentages. A cytotoxicity study was performed to observe the toxic effect that may be caused by possible Ag (I) release. According to the analysis, the release values in all products were observed in ppb level. And it is concluded that the materials produced are not degraded. Cell viability values of more than 70% were obtained. It was observed that the release of Ag (I) bound to Ag (I)-doped nHAp hexagonal structure was very low. It was concluded that the products are not degraded and Ag (I)-doped nHAp to a certain ratio is a biocompatible material that can be used in dentistry for treatment.Öğe Spectral analysis and biological activity assessment of silver doped hydroxyapatite(Taylor & Francis Ltd, 2021) Erdem, Umit; Bozer, Busra Moran; Turkoz, Mustafa B.; Metin, Aysegul U.; Yildirim, Gurcan; Turk, Mustafa; Nezir, SaffetIn this study, the hydroxyapatite biomaterials are produced by the precipitation method and the role of silver doping within the different molar ratios of 2.0, 5.0, and 10.0% are investigated with some fundamental analysis, including powder XRD, SEM, EDS, FTIR, Raman, and material densities. In vitro biocompatibility assessment is conducted with cytotoxicity and agar diffusion tests. Moreover, genotoxicity tests determine whether the biomaterials produced cause the mutations or not. In addition, a hemolytic effect test examines the variation of hemolytic behavior of compounds. Also, the cell migration experiments inspect the influence of silver ion levels in biomaterials on many biological processes. The experimental results reveal that the honeycomb-patterned morphological structures are obtained for all the products. FTIR and Raman analyses reveal that the dramatic changes in the characteristic functional group peaks are obtained with the increment in the amount of silver ions. The experimental parts related to the biocompatibility assessment of the study show that there seems to be deterioration in biocompatibility as the silver ion-doping level increases in the system. To sum up, the ideal doping value for bone tissue engineering applications is found to be 2%.
