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    Antibacterial Properties of Different Ratio Ce Doped TiO2 Nanofibers Prepared by Electrospinning Process
    (Amer Scientific Publishers, 2018) Bezir, Nalan Cicek; Evcin, Atilla; Senol, Emine; Ozcan, Burcu; Kir, Esengul; Akarca, Gokhan; Cetin, Emel Sesli
    The aim of this study was to prepare PVP/TiO2 nanofibers containing Cerium and investigate antibacterial properties of prepared nanofibers. In order to see the influence Ce doped at different ratios on the properties of TiO2 nanofibers, we prepared one pure TiO2 and Ce doped TiO2 nanofiber samples successfully by electrospinning method. 1, 2, 3, 4, and 5 wt% Ce doped TiO2 nanofibers produced at constant voltage 20 kV, constant height 8 cm and with a constant rate 0.1 mL/h. The antibacterial activities of the nanofibers were tested by using Staphylococcus aureus. The results showed that the antibacterial activity of TiO2 improves with doping of Ce. Characterization of the prepared samples was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and the differential thermal analysis/the thermal gravimetric analysis (DTA/TGA) methods.
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    Effect of concentration of Sm2O3 and Yb2O3 and synthesizing temperature on electrical and crystal structure of (Bi2O3)(1-x-y)(Sm2O3)(x)(Yb2O3)(y) electrolytes fabricated for IT-SOFCs
    (ELSEVIER SCIENCE BV, 2016) Kayali, Refik; Ozen, Murivet Kasikci; Bezir, Nalan Cicek; Evcin, Atilla
    For intermediate temperature solid oxide fuel cells (IT-SOFCs), (Bi2O3)(1-x-y)(Sm2O3)(x)(Yb2O3)(y) ternary systems (x=0.01 and y = 0.11), (x=0.05 andy= 0.07), (x=0.07 and y=0.05), and (x=0.11 and y=0.01) as electrolytes have been fabricated at different temperatures (700, 750, and 800 degrees C) by solid state ceramic technique (SST). The characterization of the samples has been performed by X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), four point-probe method (FPPM), X-ray energy diffraction spectroscopy (EDX), and differential thermal analysis (DTA). XRD measurements have shown that only the samples (Bi2O3)(1-x-y)(Sm2O3)(x)(Yb2O3)(y) (x=0.01, y=0.11 synthesized at 700, 750, and 800 degrees C) and (x=0.05, y=0.07 synthesized at 800 degrees C) have stable fluorite type face centered cubic (FCC) delta-phase. SEM images have shown the morphology of the stable samples. The conductivity and the operation temperature region of the samples have been determined from Arrhenius curves obtained from the FPPM measurements data and they vary from 1.83 to 9.95 x 10(-1) S cm(-1). Moreover, activation energy of the samples have been calculated by means of Arrhenius curves of the samples and relationships between them and the conductivity of the samples have been investigated in detail. The results obtained from XRD and FPPM measurements were confirmed by the DTA measurements. (C) 2016 Elsevier B.V. All rights reserved.
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    Indium phosphide nanofibers prepared by electrospinning method: Synthesis and characterization
    (WILEY-V C H VERLAG GMBH, 2014) Evcin, Atilla; Bezir, Nalan Cicek; Kayali, Refik; Ari, Mehmet; Kepekci, Deniz Belkis
    Nine sets of (3 x 3) InP nanofiber samples have been successfully prepared at three different voltages (20, 25, 30 kV) and at three separate heights (5, 7, 10 cm) by electrospinning with a constant precursor flow rate of 0.3 mLh(-1). The crystalline structure, thermal, morphologies and nanostructure, electrical, and optical properties of the samples are characterized by X-ray powder diffractometer (XRD) and thermal gravity-differential scanning calorimeter (TG-DSC), scanning electron microscopy (SEM), by Four-Point Probe Technique (FPPT,) and ultraviolet/visible spectrometry (UV/VIS), respectively. From these measurements, we have found the formation of stoichiometric nanostructured InP with zinc-blende structure and having lattice parameter of a = 5.874 angstrom, weight loss of 64.59% and crystallization temperature of 500 degrees C, average fiber diameter of 65.82 nm, the activation energies, E-a, of the samples, and band gap energy, E-g, of the nanofibers developed at constant applied voltage 30 kV. The band gap energies determined at different distances 5, 7, and 10 cm are found to be as 1.29, 1.37, and 1.30 eV, respectively.
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    Investigation of Antibacterial Properties of Ag Doped TiO2 Nanofibers Prepared by Electrospinning Process
    (De Gruyter Poland Sp Zoo, 2018) Bezir, Nalan Cicek; Evcin, Atilla; Diker, Ramazan; Ozcan, Burcu; Kir, Esengul; Akarca, Gokhan; Cetin, Emel Sesli
    In this study, undoped and 1, 2, 3, 4, and 5 wt % Ag-doped TiO2 nanofibers have been fabricated by the electrospinning method applying 20 kV voltages at 8 cm height with a flow rate 0.1 mL/h. The antibacterial properties of undoped and doped Ag/TiO2 nanofibers were tested on Staphylococcus aureus bacteria. The antibacterial effect of these fabricated nanofibers has been determined by disc diffusion and Baird parker methods. The results have shown that Ag/TiO2 nanofibers have an excellent antibacterial effect on this bacterium compared to pure TiO2 nanofibers. As a result, developed nanofibers can easily be applied in various fields such as biomedical sector and tissue engineering. In addition, the chemical components, morphology, and crystal structure of the nanofibers have been performed by scanning electron microscopy energy dispersive analysis (SEM-EDX), differential thermal analysis/thermal gravimetric analysis (DTA/TG), and X-ray diffraction (XRD) methods.
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    Investigation of structural, electronic and optical properties of pure and Ag-doped TiO2 nanofibers fabricated by electrospinning
    (WILEY-V C H VERLAG GMBH, 2016) Bezir, Nolan Cicek; Evcin, Atilla; Kayali, Refik; Ozen, Murivet Kasikci; Oktay, Ayse
    Pure and 1, 2, and 3 wt% Ag doped TiO2 nanofibers were prepared by electrospinning method at different applied voltages and heights at a constant flow rate of 2 mL/h. Characterization of the prepared samples was performed by x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microcopy (AFM),four point probe method (FPPM), the differential scanning calorimetry/the thermal gravimetric analysis (DSC/TGA), ultraviolet/visible spectrometry (UV/VIS), and energy dispersive X-ray spectrometer (EDX). It was found that the thermally untreated pure TiO2 nanofibers and thermally treated (at 500 degrees C) samples have the crystalline phase of anatase (A), and mixed anatase and rutile (A+R) phases, respectively. It was also observed that the content of the silver does not affect the crystal structure, but plays strengthening role in the rutile structure. SEM micrographs showed that all fabricated nanofiber samples have uniform morphologies, and AFM measurements indicated that the nanofibers were formed in three-dimensional coils. The band gap values of the nanofiber samples obtained from UV/VIS measurements revealed that band gap values of the nanofiber samples decrease while the diameter of the nanofiber increases.