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: 49Citation - Scopus: 54Closed Porosity Ceramics and Glasses(Wiley, 2020) Vakıfahmetoğlu, Çekdar; Semerci, Tuğçe; Soraru, Gian DomenicoIn the last three decades, considerable effort has been devoted to obtain both open and closed porosity ceramics & glasses in order to benefit from unique combination of properties such as mechanical strength, thermal and chemical stability at low-relative density. Most of these investigations were directed to the production and the analysis of the properties for open porosity materials, and regrettably quite a few compositions and manufacturing methods were documented for closed porosity ceramics & glasses in the scientific literature so far. This review focuses on the processing strategies, the properties and the applications of closed porosity ceramics & glasses with total porosity higher than 25%. The ones below such level are intentionally left out and the paper is set out to demonstrate the porous components with deliberately generated closed pores/cells. The processing strategies are categorized into five different groups, namely sacrificial templating, high-temperature bonding of hollow structures, casting, direct foaming, and emulsions. The principles underlying these methods are given, with particular emphasis on the critical issues that affect the pore characteristics, mechanical, thermal and electrical properties of the produced components.Article Citation - WoS: 23Citation - Scopus: 23Hot Air Permeable Preceramic Polymer Derived Reticulated Ceramic Foams(American Chemical Society, 2020) de Mello Innocentini, Murilo Daniel; Marsola, Gabriel Antonio; Orlandi Lasso, Paulo Renato; Soraru, Gian Domenico; Semerci, Tuğçe; Vakıfahmetoğlu, ÇekdarOpen and partially closed cell polymer derived ceramic, specifically silicon oxycarbide, foams were produced from commercially available polyurethane (PU) foams through the replica technique combined with the preceramic polymer pyrolysis route. The focus was directed on the role of PU morphology (cell size and open/partially closed cells), synthesis parameters (cross-linking temperature and time), and type of the polysiloxane precursors for fine-tuning the microstructural features of the resulting ceramic foams and their eventual effect on the fluid dynamic/mechanical properties. Consequently, ceramic foams having dense/hollow struts with/without hierarchical porosity were able to be manufactured and characterized in detail. The average total porosity including all compositions was above 95%, the maximum surface area was found to be reaching 79 m(2).g(-1), and the room temperature permeability measurements indicated a wide range for k(1) (0.28 x 10(-9)-11.48 x 10(-9) m(2)) and k(2) (0.34 x 10(-5)-54.17 x 10(-5) m) according to the selected PU substrate. Hot air permeation tests showed that the foams were stable up to 700 degrees C without any loss of functionality. Accordingly, they are envisioned to be employed as reusable air filtration device parts for pollutants (viruses, bacteria, dust, etc.), catalytic supports, and filter components for reactions occurring in aggressive environments.Article Citation - WoS: 19Citation - Scopus: 22Enhanced Methylene Blue Removal Efficiency of Tio2 Embedded Porous Glass(Elsevier Ltd., 2021) Ertuş, E.Burak; Vakıfahmetoğlu, Çekdar; Öztürk, AbdullahA porous glass (PG) embedded with titanium dioxide (TiO2) was produced via impregnation of the PG with Titanium (IV) Isopropoxide solution followed by crystallization. N2 sorption analyses revealed that the specific surface area (SSA) and total pore volume of the PG reached to 358 m2/g and 0.370 cm3/g, respectively. The adsorption capacity of methylene blue (MB) for the glasses was measured in the dark, instead the photocatalytic MB removal efficiency was evaluated by the degradation of MB under UV light illumination using a UV–vis spectrometer. The MB removal efficiency of the TiO2 synthesized anatase powder was only 32.3 % whereas, for TiO2 embedded PG (TiPG) it was 91.6 %, and nearly complete (> 99 %) efficacy was achieved for TiO2 embedded alkaline leached PG (TiPG-AL) under UV illumination 3 h period. Better MB removal efficiency was attributed to high SSA and dispersion of nano size anatase TiO2 crystallites within the porous structure. © 2020 Elsevier LtdArticle Citation - WoS: 23Citation - Scopus: 23Cold Sintering of Soda-Lime Glass(Elsevier Ltd., 2021) Karacasulu, Levent; Ögür, Ezgi; Pişkin, Cerem; Vakıfahmetoğlu, ÇekdarOrdinary recycled soda lime glass powder was densified via cold sintering process with the aid of concentrated NaOH solution. Increase in processing time, temperature and concentration of the NaOH solution resulted in the formation of monolithic glass artifacts with higher relative densities. The sample densified the most (95.2%) was obtained when the sintering was performed at 250˚C with a 20 min dwell time using 15 M NaOH solution.Article Citation - WoS: 37Citation - Scopus: 39Polymer-Derived Ceramic Adsorbent for Pollutant Removal From Water(John Wiley and Sons Inc., 2018) Zeydanlı, Damla; Akman, Süleyman; Ahmetoğlu, Çekdar VakıfPolymer-derived ceramic components (SiOC, sample W) were produced from preceramic polymer mixture and a catalyst. After curing and pyrolysis, some of the samples etched by hydrofluoric acid to obtain carbonaceous SiOC (C-rich SiOC, sample W-HF). W and W-HF were tested as an adsorbent material to remove both heavy-metal ions (Cr (III), Pb (III), and Cd (II)) and cationic dyes (Methylene Blue (MB), Rhodamine B (RB), and Crystal Violet (CV)) from aqueous solutions. HF-treated high surface area SiOC samples had quite high adsorption affinity for cationic dyes. According the Langmuir isotherm model the maximum dye uptake values were found to be around to 50 mg/g for sample W, whereas those for sample W-HF ranged from 104 to 186 mg/g. Regeneration studies were conducted both by heat treatment and leaching, high recovery yields (always above 97%) of MB adsorption were obtained.Article Citation - WoS: 50Citation - Scopus: 50Hierarchically Porous Polymer Derived Ceramics: a Promising Platform for Multidrug Delivery Systems(Elsevier Ltd., 2018) Vakıfahmetoğlu, Çekdar; Zeydanlı, Damla; Özalp, Veli Cengiz; Borsa, Barış Ata; Soraru, Gian DomenicoMesoporous silicon oxycarbide (SiOC) components were formed with the use of “molecular spacer” (a sacrificial vinyl-terminated linear siloxane which while decomposing during pyrolysis generates pores with size proportional to the molecular weight), followed by a post-pyrolysis etching treatment by hydrofluoric acid (HF) to obtain C-rich SiOC samples having additional micro-/mesoporosity and specific surface area reaching to 774 m2/g. The biocompatibility of the samples was validated by hemolysis test, and their cargo/drug loading capacities were studied by two different sized polypeptides as model molecules. SiOC particles showed less hemolysis compared to the reference material MCM-41. Similarly, the loading capacity and the release kinetics of bovine serum albumin (BSA) and vancomycin-loaded SiOC particles were improved compared to that of MCM-41. In the multi cargo loading/release capacity tests, done by using different sized molecules, Bio2-HF and MCM-41 were loaded both with fluorescein and BSA. While a lagging time in fluorescein release was observed for MCM-41, the release kinetics of fluorescein and BSA was not affected when they are loaded together in the hierarchical pores of Bio2-HF, allowing the release of both large and small cargo molecules. The antimicrobial activity tests showed that Bio2-HF performed better than MCM-41 particles in improving bactericidal activity.