Biomedical subjects

Tohru Okuzono

Publications and source records attributed to Tohru Okuzono.

5 recordsLinked to original sources

PubMed2006

Simple model of skin formation caused by solvent evaporation in polymer solutions.

A simple model is proposed for the skin formation in the evaporation process of a polymer solution at a free surface. In this model the skin is regarded as a gel phase formed near the free surface, and the dynamics is described by a diffusion equation for the polymer concentration with moving boundaries. The equation is solved both analytically and numerically. It is shown that the skin phase appears when the evaporation rate is high or when the initial polymer concentration is high. An analytical expression is given for the criterion for the skin phase to be formed.

Journal Article↗

PubMed2004

Theoretical modeling of photo-induced wave propagation in liquid-crystalline Langmuir monolayers.

A phenomenological model of wave propagation in photo-excited liquid-crystalline Langmuir monolayers is constructed. The spontaneous splay deformation of the liquid-crystalline order and the anisotropy of photo-excitation of molecules are taken into account in this model. Numerical simulations of the model well reproduce qualitative features of the wave propagation phenomenon observed in recent experiments. A linear stability analysis of the model equations reveals that an interplay between the spontaneous splay deformation and the anisotropy of the photo-excitation can lead to the wave propagation.

Crystallization↗

PubMed2004

Generation, propagation, and switching of orientational waves in photoexcited liquid-crystalline monolayers.

Photoinduced orientational waves in illuminated liquid-crystalline monolayers is one of the most remarkable far-from-equilibrium phenomena that systems of soft condensed matter exhibit. We model this behavior from a phenomenological point of view, taking the anisotropic photoexcitation of molecules into account. Numerical simulations as well as theoretical analyses of the model reveal that the intricate interplay between the spontaneous splay deformation of the liquid-crystalline order and the anisotropy of the photoexcitation can lead to the generation and propagation of orientational waves. The model can explain all the salient features of the phenomenon-in particular, the anomalous reversal of the propagation direction upon 90 degrees rotation of the polarization direction of illumination, which evaded theoretical explanation for nearly a decade.

Journal Article↗

PubMed2003

Traveling waves in phase-separating reactive mixtures.

A model of phase separation of chemically reactive ternary mixtures is constructed. In this model, spatially periodic structures that coherently propagate at a constant speed emerge through a Hopf bifurcation at a finite wave number. It is shown by computer simulations that both lamellar and hexagonal structures undergo a coherent propagating motion in two dimensions, and there are two types of traveling hexagons depending on the relative direction between the traveling velocity and the lattice vectors of the hexagonal structure. Amplitude equations for the traveling waves are derived, and the stability of the traveling and standing waves is discussed.

Journal Article↗

PubMed2002

Time-modulated oscillatory structures in phase-separating reactive mixtures.

We investigate the effect of temporal modulation on the spatiotemporal patterns produced by phase separation in chemically reactive ternary mixtures. The temporal modulation is introduced by making one of the reaction rates periodic in time. Our main concern is the stability of traveling waves, which appear above a Hopf-type bifurcation at a finite wave number and are stable in the absence of external modulation. It is shown by computer simulations in two dimensions that when the external modulation is present, various types of coherent standing waves emerge near the special point in the parameter space, where the Turing-type bifurcation line and the Hopf-type bifurcation line meet each other. We carry out a theoretical analysis to understand the phase diagram of the synchronized oscillatory structures obtained numerically.

Journal Article↗