Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - Scopus: 2The Surface Charge of Unsupported Nano-Structured Titania Ceramic Membrane Top Layers With Varying Calcination Temperatures(University of Chemical Technology and Metallurgy, 2019) Erdem, İlker; Çiftçioğlu, MuhsinTitania is one of the most preferable ceramic membrane materials of superior durability (as zirconia) when compared to that of other ceramics, e.g. alumina or silica. The surface charge of the membrane top layer is an important parameter of the separation performance of the multilayer ceramic membrane due to the Donnan exclusion mechanisms. In this study, the change of the surface charge of unsupported nano-structured titania top layer is investigated with calcination temperature variation. The effect observed indicates the possibility of preparation of tailor-made top layers for multilayer ceramic membranes. © 2019, University of Chemical Technology and Metallurgy.Article Citation - WoS: 3Citation - Scopus: 3Particulate Sol Route Hydroxyapatite Thin Film-Silk Protein Interface Interactions(Gazi Üniversitesi, 2010) Özcan, Selçuk; Çiftçioğlu, MuhsinHydroxyapatite (HAp) thin film coatings were prepared on bioinert glass slides by a particulate sol method and the effects of intermediate silk fibroin and silk sericin coatings on the HAp film formation and surface topography were examined. The films prepared with smaller crushed particle sols had a higher agglomeration tendency during the drying consolidation step of the thin film formation, and contained agglomerates larger in number and size, which was demonstrated experimentally and in accordance with the DLVO theory. In the thin films prepared on intermediate sericin and fibroin films the number and size of agglomerates were decisively reduced, forming homogeneous films of predominantly primary particles, especially for the larger particle size sols. The regular surface electrostatic potential arrangements of the β-sheet structures of the sericin and fibroin, and of hydroxyapatite crystals, gave rise to the coulombic attraction driven surface energy minimization, enhancing the hydroxyapatite thin film formation process. The positive degree of cooperativity in the hydroxyapatite particle deposition on the silk protein coatings was disrupted by the particle agglomeration tendency.Article Citation - WoS: 36Citation - Scopus: 42Sol-Gel Derived Mesoporous and Microporous Alumina Membranes(Springer Verlag, 2010) Topuz, Berna; Çiftçioğlu, MuhsinStable polymeric and colloidal boehmite sols were prepared by sol-gel process through controlled hydrolysis/condensation reactions. The particle sizes of the colloidal sols were in the 12-25 nm range depending on the process parameters and about 2 nm for polymeric sols. The presence of a significant increase in the microporosity content of the heat treated polymeric membranes relative to the mesoporous colloidal membranes might make the design of thermally stable microporous alumina membranes with controlled pore structures possible. The phase structure evolution in the 600-800 °C range had shown that the crystallization of the gamma alumina in the amorphous matrix starts at about 800 °C. This indicated that the pore structure stability may be enhanced through processing up to this relatively high temperature in polymeric alumina derived unsupported membranes. The permeance values of the two and three layered colloidal alumina membranes were observed to be independent of pressure which implies that the dominant gas transport mechanism is Knudsen diffusion in these structures. This was also supported by the 2.8 nm BJH pore sizes of the colloidal membranes. The Knudsen diffusion equation derived permeances of the polymeric alumina membranes with thicknesses of about 300 nm were determined to be very close to the experimentally determined permeance values. © 2010 Springer Science+Business Media, LLC.Article Citation - WoS: 32Citation - Scopus: 32The Effect of Sb Substitution of Cu in Bi1.7pb0.3sr2ca2cu 3-Xsbxoy Superconductors(John Wiley and Sons Inc., 2000) Kocabaş, Kemal; Çiftçioğlu, MuhsinThe effect of partial substitution of Cu in Bi1.7Pb0.3Sr2Ca2Cu 3-xSbxOy at x = 0.0, 0.05, 0.1, 0.15, and 0.2 levels on the electrical and structural properties was investigated in this work. X-ray diffraction analysis shows that these materials have a multiphase structure. Two different types of particles with different morphologies were observed in scanning electron micrographs. The Tc values decreased from 103.5 to 87 K for x = 0.1 Sb substitution level with a subsequent increase to 101 K at x = 0.2.