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Yayın Synergistic effect of the locust bean gum on the thermal phase transitions of kappa-carrageenan gels(Elsevier Sci Ltd, 2009-03) Arda, Ertan; Kara, Selim; Pekcan, Mehmet ÖnderSynergism between K-carrageenan and locust bean gum (LBG) was studied using the photon transmission technique. Synergistic effects in these polymeric mixtures strongly affected the physical properties of the gel structure. The transmitted light intensities, I-tr, versus temperature variations were investigated during the gelation and liquefaction processes. Slight synergistic peaks were detected in gel-sol and sol-gel transition temperatures for high kappa-carrageenan/LBG ratios (approx. 80/2). Moreover, apparent synergistic peaks were observed in gel-sol and sol-gel transition activation energies for the mixtures approximately with the ratios of 80/10.Yayın Phase transitions of kappa-carrageenan gels in various types of salts(John Wiley & Sons Inc, 2006-11-05) Kara, Selim; Arda, Ertan; Kavzak, Burhan; Pekcan, Mehmet ÖnderSol-gel and gel-sol phase transitions of K-carrageenan in various types of salts were studied using photon transmission technique. Here, LiCl, NaCl, KCl, MgCl2, CaCl2, and SrCl2 were chosen as the proper salts for the K-carrageenan-water system. Photon transmission intensity, I-tr was monitored against temperature to determine the sol-gel and gel-sol temperatures (T-sg and T-gs) and activation energies (Delta E-sg and Delta E-gs). It was observed that T-gs temperatures were notably higher than T-sg due to the hysteresis on the phase transition loops. It was observed that stronger carrageenan gels are formed in the presence of KCl compared to the others.Yayın Molecular recognition during sol-gel and gel-sol transition of kappa-iota carrageenan mixtures(Taylor & Francis ltd, 2005-12) Kara, Selim; Arda, Ertan; Pekcan, Mehmet ÖnderSol-gel and gel-sol phase transitions of kappa-iota (kappa-iota) carrageenan mixtures in two types of salts were studied using photon transmission technique. Here, KCl and CaCl2 were chosen as the proper salts for the carrageenan mixtures. Coil-to-double helix (c-h) and double helix-to-dimer (h-d) phase transitions of carrageenan mixtures in monovalent and bivalent cation solutions were studied upon heating and cooling by using photon transmission technique. Photon transmission intensity, It, was monitored against temperature to determine the (c-h) and (h-d) transition temperatures (T-ch and T-nd). Two distinct transition regions were observed in both heating and cooling of the carrageenan-bivatent CaCl2 salt system. At the first step of heating process dimers decompose into double helices by making (d-h) transition. At the high temperature region (h-c) transition takes place. Carrageenan-monovalent KCl salt system presented only (c-h) and (h-c) transitions upon cooling and heating processes. Transition temperatures at the heating and cooling processes were obtained. A hysteresis was observed between (h-c)-(c-h) and (d-h)-(h-d) transitions for the monovalent and bivalent cations respectively.Yayın Cation effects on phase transition of kappa-iota-carrageenan hybrids: a photon transmission study(Taylor & Francis Group, 2007) Pekcan, Mehmet Önder; Kara, Selim; Arda, ErtanPhase transitions of kappa-iota-carrageenan hybrid in various types of salts were studied using photon transmission technique: NaCl, KCI, MgCl2, CaCl2 and KCl+CaCl2 were chosen as the salt solutions for the carrageenan hybrid. Coil-to-helix (c-h), helix-to-dimer (h-d) and back to helix-to-coil (h-c), dimer-to-helix (d-h) phase transitions of carrageenan hybrid in these mono- and bivalent cation solutions were studied upon cooling and heating, respectively. Photon transmission intensity, It, was monitored against temperature to determine the (c-h), (h-d) and (h-c), (d-h) transition temperatures (T-ch, T-hd and T-hc, T-dh) and activation energies (Delta E-ch, Delta E-hd and Delta E-hc, Delta E-dh) of carrageenan hybrids. Two distinct transition regions were observed both during heating and cooling of the carrageenan-bivalent salt systems. During the heating process, at first dimers decompose into helices by making a (d-h) transition. Then at the high temperature region, a (h-c) transition takes place. During cooling, back transitions repeat themselves. However, the carrageenan-monovalent salt system presented only (c-h) and (h-c) transitions during the cooling and heating processes, respectively. A hysteresis was observed between (h-c)-(c-h) and (d-h)-(h-d) transitions for the monovalent and bivalent cation systems respectively.
