Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 32Citation - Scopus: 33Variation of Structural and Optical Properties of Tio2 Films Prepared by Dc Magnetron Sputtering Method With Annealing Temperature(Elsevier Ltd., 2020) Gürakar, Sibel; Ot, Hakan; Horzum, Şeyda; Serin, TülayTiO2 thin films are deposited by direct current magnetron sputtering method on the silicon and quartz substrates. The effect of annealing temperature on the film properties are analysed by using X-ray diffraction (XRD), Raman scattering, atomic force microscopy (AFM), scanning electron microscopy (SEM) and optical spectroscopy measurements. Raman and XRD results reveal that the crystal structure of the TiO2 film is strongly affected by the annealing temperature. The crystal structure of the coated film is changed from amorphous to anatase structure after annealing at 500 degrees C. Anatase and rutile phases of TiO2 start to coexist after annealing at 800 degrees C. Rutile phases of TiO2 become dominant for film annealed at 900 degrees C. SEM and AFM images uncover that the morphology, grain size and surface roughness of TiO2 films vary with the annealing temperature. The optical band gap decreases from 3.35 to 2.90 eV as the phase transforms from amorphous to rutile.Article Citation - WoS: 24Citation - Scopus: 25Investigation of the Structure of Alpha-Lactalbumin Protein Nanotubes Using Optical Spectroscopy(Cambridge University Press, 2014) Tarhan, Özgür; Tarhan, Enver; Harsa, ŞebnemAlpha-lactalbumin (α-la) is one of the major proteins in whey. When partially hydrolysed with Bacillus licheniformis protease, it produces nanotubular structures in the presence of calcium ions by a self-assembly process. This study presents investigation of α-la protein structure during hydrolysis and nanotube formation using optical spectroscopy. Before spectroscopic measurements, nanotubes were examined with microscopy. The observed α-la nanotubes (α-LaNTs) were in the form of regular hollo strands with a diameter of about 20 nm and the average length of 1 μm. Amide and backbone vibration bands of the Raman spectra displayed remarkable conformational changes in α and β domains in the protein structure during nanotube growth. This was confirmed by the Fourier-transform infrared (FTIR) spectroscopy data. Also, FTIR analysis revealed certain bands at calcium (Ca++) binding sites of COO- groups in hydrolysed protein. These sites might be critical in nanotube elongation.Conference Object Citation - WoS: 5Centralised Optical Monitoring of Tree-Structured Passive Optical Networks Using a Raman-Assisted Otdr(Institute of Electrical and Electronics Engineers Inc., 2007) Yüksel, Kıvılcım; Letheux, S.; Grillet, A.; Wuilpart, Marc; Giannone, D.; Hancq, J.; Ravet, G.; Mégret, PatriceMonitoring of tree-structured Passive Optical Networks from a central office is difficult to achieve using a standard OTDR. Switchable reflective elements placed at the ONU can help to discriminate between the branches. In parallel, a Raman assisted OTDR is shown to increase the dynamic range of the reflectometry measurement, thus enabling to detect more faults in the network, and especially fibre breaks after the splitter. ©2007 IEEE.