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TAV, CUMALİ

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2015 - 201912020 - 20223
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Author: YUMAK YAHŞİ, AYŞE ×

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    Relaxation time of polypropylene glycol and polypropylene glycol dimethylether-like polymers in terms of fluid-phase temperature and pressure dependent hole fraction
    (PERGAMON-ELSEVIER SCIENCE LTD, 2015) YUMAK YAHŞİ, AYŞE; Yahsi, Ugur; Coskun, Bilgehan; Yumak, Ayse; Boubaker, Karem; Tav, Cumali
    We present a model explaining relaxation time of PPG (polypropylene glycol) and PPGM (polypropylene glycol dimethylether) as representative compounds, with different molecular weights, PPG2 (M-w = 2 kg mol(-1)), PPG3 (M-w = 3 kg mol(-1)), PPGM1 (M-w = 1 kg mol(-1)), and PPGM2 (M-w = 2 kg mol(-1)), as a function of hole fraction at various fluid phase temperatures and high pressures. Proposed model based on the structural relaxation behavior of chain molecules given by thermo-occupancy function in terms of temperature and tempetature-pressure dependent hole fraction is discussed and compared with the free volume model. The former is the most universal behavior than the latter in terms of temperature and pressure. We discuss activation energy parameter and transmission coefficient for the species in terms of chain length and end groups such as dimethylether. Scaling relaxation time parameter in the proposed model has similar trend with relaxation time parameter of Adam-Gibbs theory. (C) 2015 Elsevier Ltd. All rights reserved.
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    FİZİK, Fen ve Mühendislik için Teknoloji Güncellemeli, Serway, Jewett,, CİLT 2, Elektrik ve Manyetizma, Optik
    (Palme Yayın Dağıtım, 2022-07-01) KESKİN, SIDDIK SİNAN; DUMLUDAĞ, FATİH; TAV, CUMALİ; YUMAK YAHŞİ, AYŞE; YAHŞİ, UĞUR; Yahşi U., Saçlı Ö. A., Keskin S. S., Tav C., Dumludağ F., Altındal A., Yumak Yahşi A., Avgın İ., Atav Ü., Ulutaş D., et al.
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    Optical and photoluminescence spectroscopy analysis and Doppler broadening annihilation radiation studies of perovskites based on La1-XNiXMnO2.75 thin layers
    (ELSEVIER GMBH, 2020) YUMAK YAHŞİ, AYŞE; Arrar, A.; Benhaliliba, M.; Boukhachem, A.; Yahsi, U.; Tav, C.; Yumak, A.; Amlouk, M.
    In this work, perovskite La1-xNixMnO2.75 (with x = 0, 0.1, 0.2, 0.3 and 0.4) is synthesized by spray pyrolysis route at 460 degrees C. X-ray pattern analysis showed orthorhombic structure of the pure and Ni-doped. Based on X-ray analysis interesting parameters are then extracted such as crystallite size, micro-strain (epsilon) and dislocation density (delta). A high transmittance coefficient at 76 % and the optical band gap varies from 2.33 to 2.85 eV are revealed by the spectroscopy analysis. The Urbach energy varies from 273 to 381.7 meV. Furthermore, refractive index, extinction coefficient, and dielectric constants versus photon wavelength are plotted for pure and Ni-doped LaMnO2.75 layers. PL measurements analysis describe peaks within violet, blue, and green emission ranges. Finally, Doppler-broadening energy studies have been performed to investigate the defect structural evolution in polycrystalline La1-xNixMnO2.75. The studies derived S, R and W parameters are used to perovskite samples.
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    Fizik, fen ve mühendislik için teknoloji güncellemeli, Serway, Jewett, cilt 1 mekanik/dalgalar/termodinamik
    (Palme Yayın Dağıtım, 2021-01-01) YAHŞİ, UĞUR; KESKİN, SIDDIK SİNAN; TAV, CUMALİ; DUMLUDAĞ, FATİH; YUMAK YAHŞİ, AYŞE; Yahşi U., Saçlı Ö. A., Keskin S. S., Tav C., Dumludağ F., Yumak Yahşi A., Avgın İ.