Phase transitions in biological gels.
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MAT Fall 2011 Seminar Series
Phase transitions in biological gels
Prof. Önder Pekcan


Faculty of Arts and Science, Kadir Has University, Istanbul
The majority of the biological gels form by physical bonding. Therefore, they can be made to
undergo sol-gel or gel-sol type phase transitions. Such geometrical transitions are also called
coil-helix or helix-coil transitions. These transitions take place with a critical exponent of 1
and ends with a Bethe lattice. The most important of all biological gels that can also be
utilized in industrial applications is a red seaweed, named carrageenan. These seaweeds,
when placed into water, undergo a volumetric phase transition, i. e., they swell. The dynamics
of this swelling can be modeled using the Li Tanaka equation and the collective diffusion
coefficients can be obtained from the swelling curves. These diffusion coefficients are very
sensitive to the concentrations of ions in the medium and determine the rate of the transition.
In this talk the correlations between such transitions and the medium characteristics will be
explained.
Wednesday, 2 November 2011, FENS G077, 14.30