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: 73Citation - Scopus: 77Zinc Oxide and Zinc Hydroxide Formation Via Aqueous Precipitation: Effect of the Preparation Route and Lysozyme Addition(Elsevier Ltd., 2015) Top, Ayben; Çetinkaya, HayrullahAqueous precipitation products of Zn(NO3)2 and NaOH obtained by changing the method of combining the reactants and by using lysozyme as an additive were investigated. In the case of single addition method, octahedral ε-Zn(OH)2 and plate-like β-Zn(OH)2 structures formed in the absence and in the presence of lysozyme, respectively. Calcination of these Zn(OH)2 samples at 700 °C yielded porous ZnO structures by conserving the template crystals. When zinc source was added dropwise into NaOH solution, predominantly clover-like ZnO crystals were obtained independent of lysozyme addition. Mixed spherical and elongated ZnO morphology was observed when NaOH was added dropwise into Zn(NO3)2 solution containing lysozyme. Lysozyme contents of the precipitation products were estimated as in the range of ∼5-20% and FTIR indicated no significant conformational change of lysozyme in the composite. These results suggest that lysozyme-ZnO/Zn(OH)2 composite materials may have a value as an antibacterial material.Article Citation - WoS: 18Citation - Scopus: 20Impact of Incorporated Oxygen Quantity on Optical, Structural and Dielectric Properties of Reactive Magnetron Sputter Grown High-? Hfo2/Hf Thin Film(Elsevier Ltd., 2014) Cantaş, Ayten; Aygün, Gülnur; Turan, RaşitHigh-κ hafnium-oxide thin films have been fabricated by radio frequency (rf) reactive magnetron sputtering technique. To avoid formation of an undesired interfacial suboxide layer between Si and high-κ film, prior to HfO2 deposition, a thin Hf buffer layer was deposited on p-type (1 0 0) Si substrate at room temperature. Effect of oxygen gas quantity in the O2/Ar gas mixture was studied for the optical and structural properties of grown HfO2 high-κ thin films. The grown thin oxide films were characterized optically using spectroscopic ellipsometer (SE) in detail. Crystal structure was studied by grazing incidence X-ray diffractometer (GIXRD) technique, while bonding structure was obtained by Fourier transform infrared spectroscopy (FTIR) analyses. In agreement with GIXRD and FTIR analyses, SE results show that any increment above ideal quantity of oxygen content in the gas mixture resulted in decrements in the refractive index and thickness of HfO2 dielectric film, while increments in SiO2 thickness. It is apparent from experimental results that oxygen to argon gas ratio needs to be smaller than 0.2 for a good film quality. The superior structural and optical properties for grown oxide film were obtained for O2/Ar gas ratio of about 0.05-0.1 combined with ∼30 W constant rf sputtering power. © 2014 Elsevier B.V. All rights reserved.Article Citation - WoS: 16Citation - Scopus: 15The Roles of Macromolecules in Imatinib Resistance of Chronic Myeloid Leukemia Cells by Fourier Transform Infrared Spectroscopy(Elsevier Ltd., 2013) Baran, Yusuf; Ceylan, Çağatay; Camgöz, AylinImatinib is a first generation tyrosine kinase inhibitor, which is used for the treatment of chronic myeloid leukemia. However, resistance to imatinib is an important problem. Different mechanisms have been explained for imatinib resistance. In this study, we examined the roles of macromolecules in imatinib resistance in K562 cells at the molecular level using Fourier Transform Infrared (FT-IR) spectroscopy. An amount of 3μM imatinib resistant cells were generated by our group and named as K562/IMA-3 cells. Changes in macromolecules in parental and resistant cells were studied by FT-IR spectroscopy. Imatinib resistance caused changes, which indicated decreases in the level of glycogen and increases in the membrane order. The amount of unsaturated lipids increased in the imatinib resistant cells indicating lipid peroxidation. Imatinib resistance caused changes in the lipid/protein ratio. The relative protein content increased with respect to nucleic acids indicating higher transcription and protein expression and structural/organizational changes in the nucleus were evident as revealed by frequency changes in the nucleic acid bands. Changes in the amide bands revealed changes in the proteome of the resistant cells. Protein secondary structural changes indicated that the antiparallel beta sheet's structure increased, however the alpha helix structure, beta sheet structure, random coil structure and turns decreased in the resistant cells. These results indicate that the FT-IR technique provides a suitable method for analyzing drug resistance related structural changes in leukemia and other cancer types.Conference Object Citation - WoS: 33Citation - Scopus: 35Effects of Physical Growth Conditions on the Structural and Optical Properties of Sputtered Grown Thin Hfo2 Films(Elsevier Ltd., 2011) Aygün, Gülnur; Cantaş, Ayten; Şimşek, Yılmaz; Turan, RaşitHfO2 thin films were prepared by reactive DC magnetron sputtering technique on (100) p-Si substrate. The effects of O2/Ar ratio, substrate temperature, sputtering power on the structural properties of HfO2 grown films were studied by Spectroscopic Ellipsometer (SE), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrum, and X-ray photoelectron spectroscopy (XPS) depth profiling techniques. The results show that the formation of a SiOx suboxide layer at the HfO2/Si interface is unavoidable. The HfO2 thickness and suboxide formation are highly affected by the growth parameters such as sputtering power, O 2/Ar gas ratio during sputtering, and substrate temperature. XRD spectra show that the deposited films have (111) monoclinic phase of HfO 2, which is also supported by FTIR spectra. XPS depth profiling spectra shows that highly reactive sputtered Hf atoms consume some of the oxygen atoms from the underlying SiO2 to form HfO2, leaving Si-Si bonds behind. © 2010 Elsevier B.V. All rights reserved.Article Citation - WoS: 4Citation - Scopus: 5Biophysical and Microbiological Study of High Hydrostatic Pressure Inactivation of Bovine Viral Diarrheavirus Type 1 on Serum(Elsevier Ltd., 2012) Ceylan, Çağatay; Severcan, Feride; Özkul, Aykut; Severcan, Mete; Bozoğlu, Faruk; Taheri, NusretThe effect of high hydrostatic pressure application on fetal bovine serum components and the model microorganism (Bovine Viral Diarrheavirus type 1 NADL strain) was studied at 132 and 220MPa pressure for 5min at 25°C. Protein secondary structures were found to be unaffected by an artificial neural network application on the amide I region for both untreated and HHP treated samples. FTIR spectroscopy study of both the HHP-treated and control samples revealed changes in the intensity of some bands in the finger-print region (1500-900cm -1) originating mainly from lipids which are thought to result from changes in the lipoprotein structure. The virus strain lost its infectivity completely after 220MPa HHP treatments. These results indicate that HHP can be successfully used for inactivation of pestiviruses while leaving structural and functional properties of serum and serum products unaffected. © 2011 Elsevier B.V.