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Öğe Comparison of in vivo effects of calcitonin, risedronate and raloxifene on erythrocyte antioxidant enzyme activity, lipid peroxidation and nitric oxide in postmenopausal osteoporosis(B M J Publishing Group, 2006) Ozgocmen, S.; Kaya, H.; Fadillioglu, E.; Yilmaz, Z.[Abstract Not Available]Öğe The effect of back electrode on the formation of electrodeposited CoNiFe magnetic nanotubes and nanowires(Elsevier Science Bv, 2010) Atalay, F. E.; Kaya, H.; Yagmur, V.; Tari, S.; Atalay, S.; Avsar, D.The electrodeposition of cobalt + nickel + iron alloy nanostructures in aqueous sulfate solution has been studied using vitreous templates placed on highly ordered porous anodic alumina oxide (AAO). During the deposition process some electrochemical bath parameters such as ion content, deposition voltage, pH and temperature of solution were kept constant. The morphological properties of the nanostructures were studied by scanning electron microscopy (SEM) and the chemical composition was determined by examination of the energy dispersive X-ray (EDX) spectra. The magnetic behaviour of the arrays was determined with a vibrating sample magnetometer (VSM). Voltammetric and galvanostatic results indicate that the back electrodes placed on AAO plays the main role in obtaining nanowire or nanotube structured material. (C) 2009 Elsevier B. V. All rights reserved.Öğe Effect of tensile stress on magnetoimpedance properties of CoNiFe/Cu wire(Iop Publishing Ltd, 2009) Bayri, N.; Kolat, V. S.; Kaya, H.; Atalay, F. E.; Izgi, T.; Atalay, S.A Co20.5Ni40.5Fe39 magnetic film was electrodeposited onto a copper wire 50 mu m in diameter. The magnetoimpedance (MI) effect, (Delta Z/Z)(H)(%) = ((Z(H)-Z(max))/Z(max)) x 100, was measured in the Co20.5Ni40.5Fe39/Cu composite wire under varying tensile stresses up to 30 MPa. The results showed that large MI and stress impedance (SI) effects can be observed in the Co20.5Ni40.5Fe39/Cu composite wire. The MI curve at zero tensile stress shows a small split peak in the low-field region. With increasing applied tensile stress, single-peak behaviour of the MI effect is observed. The magnitude of the MI and SI effects decreases with increasing tensile stress, sigma. The peak values of (Delta Z/Z)(H)(%) for the sample decrease from 265% at sigma = 0 to 39% at sigma = 30MPa at 40 kHz ac driving-current frequency. The impedance of a sample under the effect of 25 MPa tensile stress at 40 kHz ac driving-current frequency showed variations of about 146%. It was also found that the frequency value, f*, where the maximum MI effect was observed as a function of driving-current frequency, increases with increasing tensile stress.Öğe Electrochemical Capacitance of Cobalt Oxide Nanotubes on Nickel Foam(Polish Acad Sciences Inst Physics, 2013) Yagmur, V.; Atalay, F. E.; Kaya, H.; Avcu, D.; Aydogmus, E.In this study, densely packed Co3O4 nanotubes for supercapacitors have been obtained by means of chemically depositing cobalt hydroxide within a porous anodic aluminum oxide and then annealed at 360 degrees C. The morphological properties obtained Co3O4 nanotubes were studied by scanning electron microscopy, the chemical composition was determined by examination of the energy dispersive X-ray spectra. Supercapacitor characteristics such as charging/discharging and impedance (Z) characteristics were also examined. DOI: 10.12693/APhysPolA.123.215Öğe Electrochemical Impedance of Sn Nanowire Arrays(Polish Acad Sciences Inst Physics, 2014) Kaya, H.; Aydogmus, E.; Avcu, D.In this study, Sn nanowires were produced electrochemically in anodic aluminum oxide membranes. During the deposition process some parameters such as ion content, pH, deposition time, and temperature of solution were kept constant. The scanning electron microscope results showed that the diameters of produced tin nanowires were approximately 300 nm and their lengths were about 8-10 mu m. Electrochemical impedance studies of Sn nanowire arrays were also studied by Iviumstat galvanostat/potentiostat system.Öğe The fabrication of metal oxide nanostructures using Deinococcus radiodurans bacteria for supercapacitor(Elsevier Sci Ltd, 2015) Atalay, F. E.; Asma, D.; Kaya, H.; Ozbey, E.The metal oxide nanostructures with high surface-to-volume ratio have been achieved using the Deinococcus radiodurans bacteria. In particular, the morphological properties of surface-layer proteins make them an ideal type of matrix for biotemplating the direct chemical synthesis of nanostructures. Surface properties of the metal-oxide nanostructures were investigated by electron microscopy. The surface area of that was also studied by Brunauer-Emmett-Teller (BET) analysis method. The materials were used at the construction of supercapacitor as electrode active materials. (C) 2014 Elsevier Ltd. All rights reserved.Öğe The Fabrication of NiO Microtubes Using Bacillus subtilis Bacteria(Polish Acad Sciences Inst Physics, 2014) Atalay, F. E.; Asma, D.; Aydogmus, E.; Turanci, H.; Kaya, H.The nickel oxide microtubes with high surface-to-volume ratio have been achieved using the Bacillus subtilis bacteria. Surface properties of the metal-oxide nanostructured materials were investigated by electron microscopy. The surface area of that was also studied by the Brunauer-Emmett-Teller analysis method. The materials were used at the construction of supercapacitor as an electrode active material.Öğe Formation and Detection of Magnetic CoNiFe Nanowire Network Using Magnetoelastic Sensor(Springer, 2019) Atalay, S.; Kaya, H.; Atalay, F. E.; Izgi, T.; Kolat, V. S.In this study, CoNiFe magnetic nanowires were detected using a magnetoelastic sensor (ME) without any coating. Amorphous ferromagnetic ribbon of Metglass 2826 (Fe40Ni38Mo4B18) was used as a magnetoelastic sensor. The magnetoelastic ribbons were drop coated with Co12Ni64Fe24 magnetic nanowires in order to study how the mass deposition affects the resonance frequency and to determine the amount of coated nanowire. It was found that the minimum amount of detected nanowire can be as low as 200 ng. It was also shown that the nanowire network was developed on the surface of Metglass 2826 MB magnetoelastic sensor.Öğe The Formation of Free Standing NiO Nanostructures on Nickel Foam for Supercapacitors(Polish Acad Sciences Inst Physics, 2014) Atalay, F. E.; Aydogmus, E.; Yigit, H.; Avcu, D.; Kaya, H.; Atalay, S.In this study, free standing NiO nanostructures for supercapacitors were obtained by means of chemically depositing of nickel oxide on Ni foam and then they were annealed at various temperatures. The morphological properties of densely covered Ni foams were studied by scanning electron microscopy. Supercapacitor characteristics, such as charging/discharging and impedance characteristics, were also examined.Öğe La-Based Material for Energy Storage Applications(Polish Acad Sciences Inst Physics, 2017) Atalay, F. E.; Kaya, H.; Bingol, A.; Asma, D.In this work, nanostructured La-based materials were produced by chemical precipitation method onto Cladosporium cladosporioides fungal hyphae in aqueous solution. Materials were annealed at various temperatures between 100 degrees C-600 degrees C. The morphological properties of the synthesized material were studied by transmission electron microscopy. The surface area for sample annealed at 360 degrees C was determined to be 85.64 m(2)/g using Brunauer-Emmett-Teller method. The nitrogen adsorption and desorption isotherm displayed a typical type-IV isotherm. Electrochemical properties of produced material were studied using cyclic voltammetry, long term charge/discharge analysis and impedance spectroscopy in the 0.5 M Na2SO4 electrolyte. The obtained nanostructured porous electrode exhibits quasi-rectangular shaped cyclic voltammetry curves with a specific capacitance of 2190 F/g at a scan rate of 2 mV/s.Öğe Magnetoelastic sensor for magnetic nanoparticle detection(Elsevier Science Bv, 2018) Atalay, S.; Kolat, V. S.; Atalay, F. E.; Bayri, N.; Kaya, H.; Izgi, T.In this study, a magnetoelastic sensor (ME) without any coating was used to detect Fe3O4 magnetic nanoparticles (MNPs) for the first time in the literature. An amorphous 2605S3A (Fe77Cr2Si5B16) ribbon was used as an ME sensor, and samples were annealed in a furnace at 360 degrees C for 20 min to improve the ME response. A frequency shift of about 320 Hz was observed at 440 A/m magnetic field with the drop of 20 mu l MNPs on the surface of an amorphous ribbon. MNPs of 10, 5, and 1 mu l were dripped onto the surface of the ribbon and frequency shifts of about 220, 100, and 15 Hz, respectively, were obtained. The minimum number of MNPs was measured to be about 1.1x10(9), which corresponds to 0.025 mg or 1 mu l of MNPs.Öğe Magnetoimpedance effect of current-annealed CoNiFe/Cu microtubes(Elsevier, 2008) Atalay, F. E.; Kaya, H.; Atalay, S.A cobalt/nickel/iron (CoNiFe) magnetic layer was electrodeposited on a 50-mu m-diameter non-magnetic Cu wire in a sulphate bath using a constant voltage. Electrodeposited CoNiFe composite wires were submitted to current annealing at 540 mA. It was found that annealing time less than 1 min removes internal stresses produced during fabrication and that annealing times longer than 5 min induce circumferential anisotropy. Non-annealed sample showed a magnetoimpedance (MI) ratio of 412%. A maximum MI ratio of 583% was obtained after I min of current annealing. (C) 2008 Elsevier B.V. All rights reserved.Öğe Magnetoimpedance Effect on Single NiFe Nanowire(Springer, 2017) Atalay, F. E.; Kaya, H.; Atalay, S.In this study, Ni82Fe18 nanowires were deposited on Au-coated porous anodic alumina oxide (AAO) template by electrochemically. Scanning electron microscopy showed that wires have diameters of about 250-310 nm and length of 50-60 mu m. NiFe nanowire arrays embedded in AAO were mechanically polished until nanowires appeared. Later, electrical contacts were made to a single nanowire using a focused ion beam (FIB) system. Magnetoimpedance (MI) properties of single nanowire were investigated, and nearly 3.5 % MI was observed at 4 GHz driving current frequency.Öğe Magnetoimpedance effects in a CoNiFe nanowire array(Elsevier Science Sa, 2013) Atalay, S.; Kaya, H.; Atalay, F. E.; Aydogmus, E.This report describes the growth of CoNiFe nanowires into highly ordered porous anodic alumina oxide (AAO) templates by DC electrodeposition at a pH value of 2.6. Scanning electron microscopy (SEM) observations revealed that the wires have diameters of approximately 270-290 nm and a length of 25 mu m. The energy dispersive X-ray (EDX) analysis indicated that the composition of the nanowires is Co12Ni64Fe24. Electrical contacts were created on both sides of the nanowire array, and their magnetoimpedance (MI) properties were investigated. The impedance value was initially 1.2 ohm at low frequency and increased to approximately 1000 ohm for a 33-MHz driving current frequency under no applied magnetic field. All the MI curves exhibited single peak behaviour due to the high shape anisotropy. The maximum MI change at the 33-MHz driving current frequency was 2.72%. The maximum resistance change was 5.4% at 33 MHz. (C) 2013 Elsevier B. V. All rights reserved.Öğe Magnetoimpedance Effects in Electrodeposited NiFe Nanowire Array(Polish Acad Sciences Inst Physics, 2014) Aydogmus, E.; Kaya, H.; Atalay, F. E.; Atalay, S.; Avcu, D.In this work, NiFe nanowires were grown in highly ordered porous anodic alumina oxide templates by dc electrodeposition at a pH value of 2.6. Scanning electron microscopy showed that wires have diameters of about 250 310 nm and length 25-30 mu m. The energy dispersive X-ray analysis showed that the composition of the nanowires is Ni65Fe35. Electrical contacts were made on both sides of the nanowire array and their magnetoimpedance properties were investigated. All the magnetoimpedance curves showed single peak behavior due to the high shape anisotropy. The maximum magnetoimpedance change at the 79 MHz driving current frequency was approximate to 1.45%Öğe Magnetoresistance of Electrochemically Produced NiFe and CoNiFe Nanowires(Polish Acad Sciences Inst Physics, 2014) Avcu, D.; Atalay, F. E.; Aydogmus, E.; Kaya, H.; Atalay, S.CoNiFe and NiFe nanowires were electrochemically produced by dc electrodeposition on highly ordered porous anodic alumina oxide templates. Scanning electron microscope images of nanowires after removing the alumina membrane showed that these nanowires are uniform with the diameters of about 220-300 nm and about 25-30 mu m length. The energy dispersive X-ray analysis showed that the composition of the nanowires is Ni88Fe12, Co7Ni82Fe11. Magnetic field was applied by an electromagnet and resistance was measured by four point technique.Öğe Magnetoresistance of Electrodeposited Co/Cu Multilayer Nanowires(Polish Acad Sciences Inst Physics, 2015) Avcu, D.; Atalay, F. E.; Atalay, S.; Kaya, H.; Aydogmus, E.Co/Cu multilayer nanowires were electrodeposited potentiostatically on highly ordered porous anodic alumina oxide templates. Scanning electron microscopy (SEM) showed that wires have diameters of about 250-300 nm and length of 40-50 pm. Co/Cu multilayer nanowire arrays embedded in anodic alumina oxide were mechanically polished with diamond in a suspension of oil until the wires appeared. Then the top and bottom surfaces of the material were coated with a layer of Au with a thickness of 100 nm for electrical contacts. Magnetic field was applied by an electromagnet and resistance was measured by four point technique.Öğe Nanowires of Lead-Free Solder Alloy SnCuAg(Hindawi Ltd, 2011) Atalay, F. E.; Avsar, D.; Kaya, H.; Yagmur, V.; Atalay, S.; Seckin, T.Ternary Sn88Ag5Cu7, Sn93Ag4Cu3, Sn58Ag18Cu24, Sn78Ag16Cu6, Sn90Ag4Cu6, Sn87Ag4Cu9 alloy nanowires were produced at various values of deposition potential by dc electrodeposition on highly ordered porous anodic alumina oxide (AAO) templates. During the deposition process some parameters, such as ion content, deposition time, pH, and temperature of the solution, were kept constant. The diameter and length of regular Sn93Ag4Cu3 nanowires electrodeposited at -1V were determined by scanning electron microscopy (SEM) to be approximately 200-250 nm and 7-8 mu m, respectively. Differential scanning calorimetry (DSC) results indicate that the melting onset temperature of Sn93Ag4Cu3 nanowires is about 204 degrees C.Öğe Production of Y-Ba-Cu-O Nanowires and Nanotubes by Electrochemical Method(Polish Acad Sciences Inst Physics, 2013) Kaya, H.; Atalay, F. E.; Avsar, D.; Yagmur, V.; Atalay, S.In this work, the technological aspects of great importance YBa2Cu3O7-x superconducting materials were produced in the form of nanotube by electrochemical method. The electrochemical deposition conditions for the Y-Ba-Cu deposition in nanoporous Al2O3 were investigated. The heat treatment was applied to Y-Ba-Cu/Al2O3 nanopatterns, to form superconductive phase. The resulting nanostructures were found to be in length 4-5 mu m, 177-210 nm in diameter. The produced nanostructures at -4 V and more positive potentials were Y-Ba-Cu nanowires, while the nanostructures deposited at the more negative potentials were of nanotube form. DOI: 10.12693/APhysPolA.123.209Öğe The synthesis of ferromagnetic La0.75Ca0.25MnO3 nanowires by a sol-gel method(Natl Inst Optoelectronics, 2010) Atalay, F. E.; Yagmur, V.; Atalay, S.; Kaya, H.; Tari, S.; Avsar, D.In this study, densely packed La0.75Ca0.25MnO3 (LCMO) nanowires were synthesized within a porous anodic aluminum oxide (AAO) template by means of a sol-gel method using nitrate as raw material and ethylene glycol as the chelating agent. It was observed from measurements of hysteresis curves that the magnetic behavior of the LCMO nanowire arrays was strongly dependent on the pH of the solution. As it has been reported that bulk polycrystalline La0.75Ca0.25MnO3 samples have a Curie temperature of 224 K [1], it is interesting to find that nanowires produced at pH 3 show ferromagnetic properties at room temperature
