Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - Scopus: 22Multi‑purpose Reverse Logistics Network Design for Medical Waste Management in a Megacity: Istanbul, Turkey(Springer, 2022) Balcı, Esin; Balcı, Sezin; Sofuoğlu, AysunIn the study, a multi-purpose reverse logistics network has been designed to create effectual management of medical waste (MW) generated in 39 districts of Istanbul, a heavily populated city, during the COVID-19 pandemic as well as that to be generated in the next decade. With the model, the medical waste management system in Istanbul is analyzed during the pandemic and for the next 10 years. The model attempts to integrate economic, environmental, and social objectives within the sustainable development goals. It aims to maximize the number of personnel and government earnings for the estimated MW of a megacity while minimizing the total fixed cost and the cost of carbon emissions and transportation. The results indicated that the existing facilities are sufficient for the treatment and disposal of MW generated even under pandemic conditions. However, the capacity of the sterilization facility could be insufficient to treat the estimated amount of MW in the next decade. Opening a sterilization facility near the sanitary landfill in Komurcuoda with a total management cost of 62,450,332 €/year would be an optimum solution for Istanbul MW. In comparison to the single-purpose model results, the multi-purpose model resulted in approximately 42,000 € more in total cost. Sensitivity analyses show that the amount of MW has the most significant effect on the total cost. This simple model created an effective MW management proposal for Istanbul, which can be a model for megacities.Article Citation - WoS: 10Citation - Scopus: 12Enhanced Model Protein Adsorption of Nanoparticulate Hydroxyapatite Thin Films on Silk Sericin and Fibroin Surfaces(Springer, 2022) Özcan, Selçuk; Çiftçioğlu, MuhsinHydroxyapatite coated metallic implants favorably combine the required biocompatibility with the mechanical properties. As an alternative to the industrial coating method of plasma spraying with inherently potential deleterious effects, sol-gel methods have attracted much attention. In this study, the effects of intermediate silk fibroin and silk sericin layers on the protein adsorption capacity of hydroxyapatite films formed by a particulate sol-gel method were determined experimentally. The preparation of the layered silk protein/hydroxyapatite structures on glass substrates, and the effects of the underlying silk proteins on the topography of the hydroxyapatite coatings were described. The topography of the hydroxyapatite layer fabricated on the silk sericin was such that the hydroxyapatite particles were oriented forming an oriented crystalline surface. The model protein (bovine serum albumin) adsorption increased to 2.62 µg/cm2 on the latter surface as compared to 1.37 µg/cm2 of hydroxyapatite on glass without an intermediate silk sericin layer. [Figure not available: see fulltext.].Book Part Polyelectrolytes Thermodynamics and Rheology Preface(Springer, 2014) Visakh, P. M.; Bayraktar, Oğuz; Alfredo Pico, Guillermo[No abstract available]Book Part Citation - Scopus: 6Recent Advances in Chitosan-Based Systems for Delivery of Anticancer Drugs(Springer, 2020) Polat, Mehmet; Polat, HürriyetProblems in transporting drug molecules to tumor sites in required dose or constitution lead to low efficacy and significant side effects. Shielding the drug molecules in micelles, liposomes, or nanoparticles is a major line of investigation to improve chemotherapeutic treatment. Though compatibility for proper envelopment of the drug and timely release at the tumor site are required of such a carrier, protecting its own physicochemical and morphological integrity during transport is another precondition. Because of its superior polymerization capability, biocompatibility, pH dependence, and charging characteristics, chitosan has been in the forefront of potential drug carriers. Numerous synthesis routes for chitosan-based nanocarriers have been suggested to the extent that a search of the literature published since 2000 with the keywords “novel + nano + chitosan” in the title results in 527 articles, indicating the bewildering quality and quantity of the new information. This review was carried out not only to peruse this large amount of work on chitosan-based anticancer drug delivery but also to extract manageable patterns from numerous synthesis routes. The main conclusion is that the synthesis methods suggested in literature can be combined into two main routes, and the degree of hydrophobicity of the drug determines which route should be followed. © Springer Nature Singapore Pte Ltd. 2019.Article Citation - WoS: 17Citation - Scopus: 19Heavy Naphtha Upgrading by Catalytic Reforming Over Novel Bi-Functional Zeolite Catalyst(Springer, 2018) Ahmedzeki, Nada S.; Al-Tabbakh, Ban A.; Antwan, Maher B.; Yılmaz, SelahattinNaphtha catalytic reforming process using bimetallic platinum and titanium loaded on nano synthesized HY zeolite was investigated for the product octane number enhancement. The activity of five samples of the prepared catalyst with different bimetallic loading of 0.13, 0.25 wt% Pt and 0.75, 1, 2.2 wt% Ti were investigated for Iraqi heavy naphtha catalytic reforming at the temperature range of 490, 500 and 510 degrees C and pressure of 10 bar in a packed bed pilot plant reactor. The best result of the research octane number was 84 for reformate product using the sample of 0.13% Pt-0.75% Ti%/HY zeolite at temperature 510 degrees C and 10 bar achieving 47% increase. All samples of the prepared catalyst showed a good stability during the operation at severe conditions and the maximum carbon content was about 9% due to the deposition of coke precursor on the catalyst surface. The reformate yield was investigated for all catalyst samples under 10 and 20 bars and the same range of temperature and ranged from 89 to 94%. These results are encouraging for future possible replacement of the conventional catalyst by the local synthetic zeolite. Octane number was correlated on the basis of constituent's boiling points. The maximum absolute error between the experimental and predicted octane number was about 3 and 5% using 10 and 20 bar respectively.Article Citation - WoS: 32Citation - Scopus: 36A Novel Bilayer Zein/Mmt Nanocomposite Incorporated With H. Perforatum Oil for Wound Healing(Springer, 2020) Güneş, Seda; Tamburacı, Sedef; Tıhmınlıoğlu, FundaRecently, layered structures composed of nanofibers have gained attention as a novel material to mimic skin tissue in wound healing applications. The aim of this study is to develop a novel hybrid bilayer material composed of zein based composite film and nanofiber layers as a wound dressing material. The upper layer was composed of H. perforatum oil incorporated zein film including MMT and the bottom layer was comprised of 3D electrospun zein/MMT nanofibers to induce wound healing with the controlled release of H. perforatum oil. The bilayer composites were characterized in terms of mechanical test, WVP, water uptake and surface wettability. Antimicrobial activity of the wound dressings against microorganisms were investigated by disc diffusion method. In vitro cytotoxicity of monolayer film and bilayer structure was performed using WST-1 assay on HS2 keratinocyte and 3T3 cell lines. Results indicated that the prepared monolayer films showed appropriate mechanical and gas barrier properties and surface wettability for wound healing. Controlled release of H. perforatum oil was obtained from fabricated membranes up to 48 h. Bilayer membranes showed antimicrobial activity against E. coli, S. aureus, and C. albicans and did not show any toxic effect on NIH3T3 mouse fibroblast and HS2 keratinocyte cell lines. In vitro scratch assay results indicated that H. perforatum oil had a wound healing effect by inducing fibroblast migration. The proliferation study supported these results by increasing fibroblast proliferation on H. perforatum oil loaded bilayer membranes.Article Citation - WoS: 11Citation - Scopus: 13Remarkable Effects of Deep Eutectic Solvents on the Esterification of Lactic Acid With Ethanol Over Amberlyst-15(Springer, 2020) Ünlü, Ayşe Ezgi; Arıkaya, Azime; Altundağ, Aybike; Takaç, SerpilDeep eutectic solvents (DESs) are widely used in numerous reactions both as a solvent and a catalyst. In this study, different types of DESs were investigated as a supplementary component for Amberlyst-15 to enhance its catalytic activity in the esterification reaction of lactic acid with ethanol. The effects of the following parameters such as DES type, choline chloride : glycerol (ChCl-Gly) (1 : 2) amount, molar ratio of reactants, temperature and agitation rate on the initial rate of reaction and yield of ethyl lactate were investigated. According to the results, DESs alone did not have any catalytic effect on the esterification; however, DESs together with Amberlyst-15 provided a significant increase in the initial rate of reaction and yield. The activation energy of the reaction decreased significantly with the combined use of Amberlyst-15 and ChCl-Gly (1 : 2). Internal and external mass transfer limitations were found to be negligible under optimum reaction conditions.Article Citation - WoS: 4Citation - Scopus: 3Modification of Surface Charge Characteristics for Unsupported Nanostructured Titania-Zirconia Uf/Nf Membrane Top Layers With Calcination Temperature(Springer, 2020) Erdem, İlker; Çiftçioğlu, MuhsinCeramic membranes are more advantageous alternatives especially for harsh working conditions when compared with the polymeric membranes. The porous multilayer structure of the ceramic membranes (composed of support, intermediate, and top layers) can be prepared via different oxides. Titania and zirconia, having superior properties, are mainly preferred for the top layer formation. The separation properties of the membrane are both dependent on pore morphology and surface charge of the oxide(s) forming the top layer. The effect of surface charge in separation may be very significant in case of filtration of charged species with relatively lower mass as in the ultrafiltration (UF) and nanofiltration (NF). In this study, unsupported membrane top layers were prepared with varying titania/zirconia ratios by sol-gel technique. Their surface charges at different pH conditions after calcination at varying temperatures (400 degrees, 500 degrees, and 600 degrees C) were determined. The surface charge of the pure titania (full Ti) top layer was decreasing with the increasing calcination temperature. The highest magnitudes of zeta potential for both acidic and basic conditions were measured via Zr rich top layer (TiZr2575) at calcination temperatures >= 500 degrees C, which was composed of anatase, rutile (titania), and tetragonal (zirconia) phases after calcination. The tailor-made top layer can be prepared with modifications during membrane preparation.Book Part Citation - WoS: 28Citation - Scopus: 26Laos (large Amplitude Oscillatory Shear) Applications for Semisolid Foods(Springer, 2019) Yazar, Gamze; Çağlar Duvarcı, Özlem; Yıldırım Ertürk, Merve; Kokini, Josef L.The rheological behavior of semisolid foods under large amplitude oscillatory shear (LAOS) can offer more detailed understanding of structural changes occurring during processing and consumption compared to traditional rheometry. This chapter focuses on a detailed description of LAOS measurements, including theory, testing method, data interpretation, and corrections. It also discusses LAOS application to food systems with different core structures ranging from dilute dispersions to gels, foams, emulsions, and soft elastic networks, along with a special emphasis on yogurt. Type of stress responses for different rheological behavior, Lissajous-Bowditch curves, and the resulting LAOS parameters e3/e1, ?3/?1, S, and T) are used to understand the structural changes in all of these foods with special emphasis on high-fat, low-fat, and non-fat yogurt. © 2019, Springer Nature Switzerland AG.