Browsing by Author "Boyaci, Ismail H."

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Oxidative Stability of Natural and Chemically Interesterified Cottonseed, Palm and Soybean Oils
(Wiley, 2007) Basturk, Ayhan; Javidipour, Issa; Boyaci, Ismail H.
The effect of interesterification on oxidative stability of cottonseed, palm and soybean oils stored under oven conditions at 45, 60 and 75C was evaluated by measuring the peroxide values (PV), anisidine values (AV) and Totox values at different time intervals. Fatty acid composition and tocopherol contents of oil samples were determined before and after interesterification. Interesterification reduced the tocopherol content of oils. The interesterified oils showed lower PV and AV than their non-interesterified counterparts in all temperatures and time intervals. The primary and secondary oxidation reaction constants and reaction orders were investigated as a function of the reaction temperature. The interesterified oils showed lower reaction rate constants than the non-interesterified samples. Based on PV, AV and reaction rate constants, the oxidative stability of interesterified oils were higher than their non-interesterified counterparts.
Quantitative Characterization of Magnetic Mobility of Nanoparticle in Solution-Based Condition
(Bentham Science Publ Ltd, 2015) Rodoplu, Didem; Boyaci, Ismail H.; Bozkurt, Akif G.; Eksi, Haslet; Zengin, Adem; Tamer, Ugur; Tugcu Demiroz, Fatmanur
Magnetic nanoparticles are considered as the ideal substrate to selectively isolate target molecules or organisms from sample solutions in a wide variety of applications including bioassays, bioimaging and environmental chemistry. The broad array of these applications in fields requires the accurate magnetic characterization of nanoparticles for a variety of solution based-conditions. Because the freshly synthesized magnetic nanoparticles demonstrated a perfect magnetization value in solid form, they exhibited a different magnetic behavior in solution. Here, we present simple quantitative method for the measurement of magnetic mobility of nanoparticles in solution-based condition. Magnetic mobility of the nanoparticles was quantified with initial mobility of the particles using UV-vis absorbance spectroscopy in water, ethanol and MES buffer. We demonstrated the efficacy of this method through a systematic characterization of four different core-shell structures magnetic nanoparticles over three different surface modifications. The solid nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD) and saturation magnetization (Ms). The surfaces of the nanoparticles were functionalized with 11-mercaptoundecanoic acid and bovine serum albumin BSA was selected as biomaterial. The effect of the surface modification and solution media on the stability of the nanoparticles was monitored by zeta potentials and hydrodynamic diameters of the nanoparticles. Results obtained from the mobility experiments indicate that the initial mobility was altered with solution media, surface functionalization, size and shape of the magnetic nanoparticle. The proposed method easily determines the interactions between the magnetic nanoparticles and their surrounding biological media, the magnetophoretic responsiveness of nanoparticles and the initial mobilities of the nanoparticles.