Yazar "Aksu, Mehmet Levent" seçeneğine göre listele

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    Characterization of boron doped Cobalt/Zinc acetate composite fibers
    (Hacettepe University, 2009) Uslu, İbrahim; Gökmeşe, Faruk; Atakol, Orhan; Aksu, Mehmet Levent
    PVA/cobalt acetate/zinc acetate doped with boron composite fibers were prepared by electrospinning technique. Electrospinning was performed by putting solutions at different applied voltage in a range from 13 to 18 kV. The fibers were measured and characterized by viscometer, conductiometer (with fourpoint probe), Fourier transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The viscosity of the Boron doped solution was higher and favoring the formation of thinner and uniform nanofibers. DSC analysis shows that when boron is added to the polymer it increases the crosslinking and amorphous structure of PVA/ cobalt and zinc acetate composite polymer is increased.
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    Electrochemical corrosion properties of metal alloys used in orthopaedic implants
    (2009) Songür, Murat; Çelikkan, Hüseyin; Gökmeşe, Faruk; Şimşek, S. Aykin; Altun, N. Şükrü; Aksu, Mehmet Levent
    This study concerns an investigation of the corrosion behavior of 316 stainless steel, CoCrMo and Ti6Al4V alloys in simulated body conditions (ringer lactate) at 37 °C by the use of Tafel plots, mixed potential and electrochemical impedance spectroscopy (EIS). Ti6Al4V alloy has the highest corrosion resistance followed by CoCr alloy. Ti6Al4V-CoCrMO was the best couple for galvanic corrosion with the minimum galvanic potential and current values according to mixed potential theory and Tafel method. It was concluded that Ti6Al4V was the most suitable material for implant applications in the human body. © 2009 Springer Science+Business Media B.V.
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    Electrochemical investigation of Zinc(II)-furdap amide complex in DMSO medium
    (2009) Gökmeşe, Faruk; Gökmeşe, Ebru; Hamurcu, Fatma; Çelikkan, Hüseyin; Aksu, Mehmet Levent
    The electrochemical behavior of Zinc(II)-furdap amide complex has been investigated by the use of several electrochemical methods in DMSO on platinum electrode. Both the ligand and the complex gave one electron transfer reduction. Although there was no oxidation peak observed corresponding to the reduction of ligand, there was a corresponding oxidation peak appeared for the complex. The number of electrons transferred was calculated as 1 by the use of bulk electrolysis, rotating disc electrodes employing KouteckTimesNewRomanPSMT.0.5 -Levich equation. The reversibility tests revealed that the reaction followed a quasi reversible mechanism. The mechanism was also confirmed by simulation studies. ks and ? values were found to be 1.0×10-7 cm s-1 and 0.4, respectively. The diffusion coefficient (D) was found as 6.93 ×10-5 cm2 s-1 by the use of Cottrell slope obtained from chronoamperometry experiments and ultra micro disc steady state current (iss). © 2009 Bentham Science Publishers Ltd.
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    Fabrication and characterization of boron doped Ni/Zn acetate nanofibers
    (2009) Uslu, İbrahim; Öztürk, M. Kemal; Aksu, Mehmet Levent; Gökmeşe, Faruk
    This study is related to the preparation of boron doped Nickel/Zinc metal fibers prepared by the use of electrospinning technique. The originality of this study is the addition of boron to metal acetates. The addition of boron did not only increase the thermal stability of the fibers, but also increased their diameters, which gave stronger fibers. The FT-IR spectra of the fibers were in good accordance with literature. The differential scanning calorimetry (DSC) results indicate that the glass transition (Tg) and melting temperatures (Tm) showed great change with the addition of boron and boron doped fibers were observed to degrade at higher temperatures. The SEM appearance of the fibers showed that the addition of boron resulted in the formation of cross linked bright surfaced fibers.
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    Fabrication and characterization of boron supported YBCO superconductive nanofibers by electrospinning
    (2010) Uslu, İbrahim; Öztürk, M. Kemal; Aksu, Mehmet Levent; Gökmeşe, Faruk
    This study is related to the preparation of boron supported YBa2Cu3O7 (YBCO) superconducting material. The first step was the preparation of a composite formed by mixing yttrium, barium, and copper acetates with polyvinyl alcohol (PVA) at a suitable temperature. The resulting composite polymer was electrospun to produce nanofibers. Finally, the obtained nanofibers were subjected to thermal treatments at 500°C, 600°C and 1000°C to elucidate their morphological properties. The conductivity of the nanofibers was measured by the four probe techniques, and the boron supported polymer was found that it had a higher conductivity. Differential Scanning Calorimetry (DSC) data for the boron doped material revealed that the addition of boron increased the thermal resistance of the fibers. Scanning electron microscopy (SEM) images of the fibers showed that they were homogeneously electrospun, and there was no beading or heaping on them. © 2010 Bentham Science Publishers Ltd.
  • Küçük Resim
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    Nanofibers by electrospinning of nylon 6 doped with boron
    (Hacettepe University, 2009) Uslu, İbrahim; Altaş, Ayşenur; Aksu, Mehmet Levent; Gökmeşe, Faruk
    In this study, Nylon 6 was successfully cross-linked with boron using formic acid as solution. Electrospinning process was performed by putting hybrid nylon 6/boric acid solutions at different applied voltage in a range from 20 to 25 kV using a high voltage power supply. Nylon has been widely used in industry because of its good mechanical properties. The use of boron improves the strength, flame retardant characteristics and flexibility of the nylon 6 fibers. The structures of the nanofibers synthesized are characterized by the Fourier transformed infrared spectroscopy (FTIR), thermo gravimetric and differential thermal analysis (TG/DTA), differential scanning calorimetry (DSC), atomic force microscopy (AFM), and scanning electron microscopy (SEM). DSC and TGA analysis revealed that stability of electrospun nylon 6 fiber is higher than non spun sample and increase of boric acid content increases the stability of the polymer. It is observed from the SEM images that the diameters of the fibers decreased with boron content increased. FTIR analysis revealed that all characteristic N-H structures are observed and consistent with literature.