Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Conference Object Citation - WoS: 24Effect of pH and Hydration on the Normal and Lateral Interaction Forces Between Alumina Surfaces(2006) Polat, Mehmet; Sato, Kimiyasu; Nagaoka, Takaaki; Watari, KojiNormal and lateral interaction forces between alumina surfaces were measured using Atomic Force Microscopy-Colloid Probe Method at different pH. The normal force curves exhibit a well-defined repulsive barrier and an attractive minimum at acidic pH and the DLVO theory shows excellent agreement with the data. The normal forces are always repulsive at basic pH and the theory fails to represent the measurements. Lateral forces are almost an order of magnitude smaller in the basic solutions. These differences, which have important implications in the study of stability and rheology, are attributed to the hydration of the alumina surface at basic pH. © 2013 Elsevier B.V., All rights reserved.Conference Object Effect of Some Physical, and Chemical Variables on Flocculation and Sediment Behaviour(A.A. Balkema Publishers, 2000) Polat, Hürriyet; Polat, Mehmet; İpekoğlu, ÜnerEffect of some chemical and physical variables on the settling rate, final sediment height, sediment viscosity and supernatant turbidity of a clay sample was studied using various polyacrylamide type flocculants. Increasing flocculant concentration significantly increased both the settling rate and sediment viscosity. More importantly, changes in the final sediment, height, hence the packing density, was minimal for all the conditions tested once the sediment was allowed to consolidate. Also, the mode of addition of the polymer, at once or continuous, did not seem to affect any of the parameters measured. Conditioning time seemed to alter the settling rate at low polymer concentrations, but had no effect at high polymer concentrations. However, increasing the conditioning time caused a decrease in the sediment viscosity. Different types of the polyacrylimides generated different settling rates at a given concentration, but the final sediment height was nearly independent of polymer type.Conference Object Predicting Drying in Solvent-Coated Polymeric Films(American Chemical Society, 2000) Alsoy Altınkaya, Sacide; Duda, John Larry[No abstract available]Conference Object Visualization of Equilibrium Fcc Catalyst Surface by Afm and Sem-Eds(American Chemical Society, 2003) Bayraktar, Oğuz; Erdoğan, G.; Kugler, Edwin L.[No abstract available]Conference Object Antioxidant, Antimicrobial and Cytotoxic Activities of Some Turkish Plant Extracts(John Wiley and Sons Inc., 2006) Altıok, Evren; Asbagh, L. Abbasi; Bulut, Çisem; Ülkü, Semra; Bayraktar, OğuzPlant extracts have been known to possess notable biological activity, including antioxidant, antimicrobial and cytotoxic properties. There is a growing interest in the use of natural products in the human food industries as consumer resistance to synthetic additives increases. These products can be used to improve human health. In vitro antioxidant, antimicrobial and cytotoxic activities of ethanol extracts of some plants from Urla region in Turkey were investigated. Plant materials were collected from Pistacia lentiscus, Vitex agnus-castus, Cistus creticus and Nerium oleander in October, November and December.Article Citation - WoS: 8Citation - Scopus: 9Polymeric Thermal Analysis of C+h and C+h+ar Ion Implanted Uhmwpe Samples(Elsevier Ltd., 2007) Kaya, N.; Öztarhan, Ahmet M.; Urkaç, Emel Sokullu; Ila, D.; Budak, S.; Oks, E.; Tıhmınlıoğlu, Funda; Muntele, C.Chemical surface characterization of C + H hybrid ion implanted UHMWPE samples were carried out using DSC (differential scanning calorimeter) and TGA (thermal gravimetric analysis) techniques. Samples were implanted with a fluence of 10(17) ion/cm(2) and an extraction voltage of 30 kV. The study of TGA and DSC curves showed that: (1) Polymeric decomposition temperature increased, (2) T-m, Delta C-p and Delta H-m values changed while Delta C-p and Delta H-m increased. T-g value could not be measured, because of some experimental limitations. However, the increase in Delta H-m values showed that T-g values increased, (3) the branch density which indicated the increase in number of cross-link (M-c) decreased in ion implanted samples and (4) increase in Delta H-m values indicated increase in crystallinity of implanted surface of UHMWPE samples.Conference Object Hidrofobik İlaç Taşıyıcısı Olarak Akrilik Yıldız Blok Kopolimerler(Institute of Electrical and Electronics Engineers Inc., 2009) Genç, Gözde; Batıgün, Ayşegül; Bayraktar, Oğuz; Altıntaş, Özcan; Tunca, Ümit; Hizal, GürkanAmphiphilic poly(methyl methacrylate)-b-poly(acrylic acid) (PMMA-b-PAA) copolymers with 4 and 6 arms were synthesized by Atomic Transfer Radical Polymerization (ATRP). The polymers were characterized by GPC, H-NMR and FTIR analysis. Polymer samples synthesized at various molecular weights between 18-80 kDa were investigated in terms of maximum loading capacity and critical micelle concentration by fluorescence spectroscopy. 4 arm PMMA-b-PAA (MW 30 kDa) was loaded with hydrophobic model drug indomethacin with an extremely high drug loading efficiency (22.5% drug content). Drug loaded polymer formed a stable and biodegradable complex in aqueous medium.Conference Object Structural and Thermal Characterization of Ti+o Ion Implanted Ultrahigh Molecular Weight Polyethylene (uhmwpe)(American Institute of Physics, 2009) Öztarhan, Ahmet; Urkaç Sokullu, Şadiye Emel; Tıhmınlıoğlu, Funda; Kaya, N.; Ila, Daryush; Budak, S.; Nikolaev, A.In this work, Metal-Gas Hybrid Ion Implantation technique was used as a tool for the surface modification of Ultra High Molecular Weight Polyethylene (UHMWPE). Samples were Ti + O ion implanted by using Metal-Vapour Vacuum Arc (MEVVA) ion implanter to a fluence of 5x10(16) ion/cm(2) for each species and extraction voltage of 30 kV. Untreated and surface treated samples were investigated by Rutherford Back Scattering (RBS) Spectrometry, Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR) Spectroscopy, Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Results indicate that Ti + O ion implantation can be applied on UHMWPE surfaces successfully. ATR-FTIR spectra indicate that the C-H concentration on the surface decreased after Ti + O implantation. Thermal characterization with TGA and DSC shows that polymeric decomposition temperature is shifted after ion implantation.Conference Object Heavy Metal Removal Using Natural Zeolite Packed Ion Exchange Column(American Chemical Society, 2008) Balköse, Devrim; Ülkü, Semra[No abstract available]Conference Object Citation - Scopus: 4Trans-resveratrol’ün Kitosan Mikroküreler İçerisindeki Kararlılığı(Institute of Electrical and Electronics Engineers Inc., 2009) Altıok, Duygu; Altıok, Evren; Bayraktar, Oğuz; Tıhmınlıoğlu, Fundatrans-Resveratrol, (3,5,4?-trihydroxy-trans-stilbene), a phenolic compound present in some plant species, have been shown to posses antioxidative, anticarcinogenic and antitumour properties. However, under UV light, it turns into -cis form and looses its bioactivity.This study aims to increase the stability of trans-resveratrol by loading it into chitosan microspheres. Within this context, the trans-resveratrol loaded chitosan microspheres was produced by spray drying and then the resultant microspheres were characterized. The particle size and the surface morphology of resultant microspheres were investigated by scanning electron microscope (SEM) and the thermal properties were determined by thermogravimetry analyser(TGA). The stability of free and that of inside the microspheres was determined by high performance liquid chromatography (HPLC). It was found that the stability of trans-resveratrol incorporated into chitosan microspheres kept constant. ©2009 IEEE.