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    A chemosensitive-based ammonia gas sensor with PANI/PEO-ZnO nanofiber composites sensing layer
    (Emerald Group Publishing Ltd, 2023) Ege, Gozde Konuk; Akay, Ozge; Yuce, Huseyin
    PurposeThis study aims to investigate the ammonia-sensing performance of polyaniline/polyethylene oxide (PANI/PEO) and polyaniline/polyethylene oxide/zinc oxide (PANI/PEO-ZnO) composite nanofibers at room temperature. Design/methodology/approachGas sensor structures were fabricated using microfabrication techniques. First, onto the SiO2 wafer, gold electrodes were fabricated via thermal evaporation. PANI/PEO nanofibers were produced by the electrospinning method, and the ZnO layer was deposited by using radio frequency (RF) magnetron sputtering on the electrospun nanofibers as a sensing layer. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction were performed to characterize the analysis of nanofibers. After all, gas sensing analysis of PANI/PEO and PANI/PEO/ZnO nanofibers was conducted using an experimental setup at room temperature conditions. Furthermore, the impact of humidity (17%-90% RH) on the sensor resistance was actively investigated. FindingsFTIR analysis confirms the presence of functional groups of PANI, PEO and ZnO in nanofiber structure. SEM micrographs demonstrate beads-free, thinner and smooth nanofibers with ZnO contribution to electrospun PANI/PEO nanofibers. Moreover, according to the gas sensing results, the PANI/PEO nanofibers exhibit 115 s and 457 s response time and recovery time, respectively. However, the PANI/PEO/ZnO nanofibers exhibit 245 s and 153 s response time and recovery time, respectively. PANI/PEO/MOx composite nanofibers ensure stability to the NH3 gas owing to the high surface/volume ratio and decrease in the humidity dependence of gas sensors, making gas sensors more stable to the environment. Originality/valueIn this study, ZnO was deposited via RF magnetron sputtering techniques on PANI/PEO nanofibers as a different approach instead of in situ polymerization to investigate and enhance the sensor response and recovery time of the PANI/PEO/ZnO and PANI/PEO composite nanofibers to ammonia. These results indicated that ZnO can enhance the sensing properties of conductive polymer-based resistive sensors.
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    A fabrication and characterization of luffa/PANI/PEO biocomposite nanofibers by means of electrospinning
    (Emerald Group Publishing Ltd, 2023) Ege, Gozde Konuk; Yuce, Huseyin; Akay, Ozge; Oner, Hasbi; Genc, Garip
    Purpose This paper aims to address the production of biocomposite nanofibers using luffa natural fibers and polyaniline conductive polymer/polyethylene oxides (PANI/PEO). Design/methodology/approach In this study, luffa natural fibers are extracted by chemical method. After mixing the treated luffa (TL) with the PANI/PEO solution, TL/PANI/PEO nanofibers were produced by electrospinning (ES) method under different ES parameters to examine the optimal conditions for nanofiber production. Then TL/PANI/PEO biocomposite nanofibers prepared in different weight ratios were produced to analyze the effects of luffa in the morphology and thermal properties of the biocomposite nanofibers. The characterization analysis of TL/PANI/PEO biocomposite nanofibers was performed by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) analysis methods. Findings The analysis shows that different weight ratios of TL to PANI/PEO changed the morphology of the membrane. When increasing the weight ratio of TL, the morphological structure of TL/PANI/PEO transformed from nanofiber structure to thin film structure. The appearance of O-H peaks in the FTIR results proved the existence of TL in PANI/PEO nanofibers (membrane). Moreover, an increase in the weight ratio of luffa from 2% to 7.5% leads to an increase in the peak intensity of the O-H group. Regarding DSC analysis, biocomposite nanofibers improved the thermal properties. According to all results, 2%wt TL/PANI/PEO showed optimal morphological properties. Originality/value Plant cellulose was extracted from the luffa, one of the natural fibers, by method of alkali treatment. A new type of biocomposite nanofibers was produced using TL blend with PANI via electrospinning method.
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    Preparation of a sustainable bio-copolymer based on Luffa cylindrica cellulose and poly(e-caprolactone) for bioplastic applications
    (Elsevier, 2022) Akay, Ozge; Altinkok, Cagatay; Acik, Gokhan; Yuce, Huseyin; Ege, Gozde Konuk; Genc, Garip
    In this research, a bio-based graft copolymer (LCC-g-PCL) based on the cellulose of Luffa cylindrica (LCC) main chain possessing poly(epsilon-caprolactone) (PCL) pendant groups is synthesized through a grafting from approach via ring-opening polymerization (ROP). For this purpose, LCC, extracted from luffa sponges by combined method, is utilized for ROP of epsilon-caprolactone (epsilon-CL) as a macro-initiator in the presence of stannous octoate as a catalyst. Fourier transform infrared (FT-IR), proton and carbon nuclear magnetic resonance (H-1 NMR and C-13 NMR) spectroscopies are utilized to structurally indicate the success of ROP, while the achieved graft copolymer is analyzed in detail by comparing with LCC and neat PCL in terms of wettability, thermal and degradation behaviors by conducting water contact angle (WCA) measurements, thermogravimetric and differential scanning calorimetry analyses (TGA and DSC) and in vitro both hydrolytic and enzymatic biodegradation tests, respectively. The results of conducted tests show that the incorporation of PCL groups on LCC provide the increasing hydrophobicity. In addition, the degradation behavior of the LCC-g-PCL copolymer is found to be more pronounced under enzymatic medium rather than hydrolytic conditions. It is anticipated from the results that LCC-g- PCL can be a potential eco-friendly material particularly in bioplastic industry.
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    Surgical Planning and Optimization of A Full Spine Surgery
    (IEEE, 2019) Ege, Mucahit; Kucuk, Serdar; Cakir, Ozgur; Aydin, Levent; Dilek, Riza; Ege, Gozde Konuk
    3D scanning technologies have become widely used for medical needs such as anatomical models, biocompatible implants and orthotic / prosthetic models. However, the use of 3D visuals of the scanned tissues using two-dimensional computer screens cannot give the desired effect. Although surgical planning with virtual reality technology provides more accurate results, it cannot be performed in every hospital due to high costs of the system. In this study, the operation of an advanced scoliosis patient was planned in advance. An ideal protocol to be used especially in complex spine operations was determined and its suitability to the target anatomical tissue structure was analyzed. At the same time, a surgical planning system based on layered manufacturing technologies to realize the production of the mentioned anatomical model is introduced.