We discuss the dynamics of the formation of liquid crystalline phase of rod-like polymer solutions, particularly the behavior of spinodal decomposition which should be observed when the system is suddenly brought into a thermodynamically unstable region. The growth rate of the concentration fluctuation is calculated as a function of the wave number. It is shown that these growth rates are governed by the translational motion, not the rotational motion. The dynamical structure factor in the isotropic phase is also calculated.

The investigation of tripeptide aldehydes as reversible covalent inhibitors of human rhinovirus (HRV) 3C protease (3CP) is reported. Molecular models based on the apo crystal structure of HRV-14 3CP and other trypsin-like serine proteases were constructed to approximate the binding of peptide substrates, generate transition state models of P1-P1' amide cleavage, and propose novel tripeptide aldehydes. Glutaminal derivatives have limitations since they exist predominantly in the cyclic hemiaminal form. Therefore, several isosteric replacements for the P1 carboxamide side chain were designed and incorporated into the tripeptide aldehydes. These compounds were found to be potent inhibitors of purified HRV-14 3CP with Kis ranging from 0.005 to 0.64 microM. Several have low micromolar antiviral activity when tested against HRV-14-infected H1-HeLa cells. The N-acetyl derivative 3 was also shown to be active against HRV serotypes 2, 16, and 89. High-resolution cocrystal structures of HRV-2 3CP, covalently bound to compounds 3, 15, and 16, were solved. These cocrystal structures were analyzed and compared with our original HRV-14 3CP-substrate and inhibitor models.

Late stages of phase separation/gelation of isotropic solutions of rodlike polymers by video microscopy J. Chem. Phys. 92, 5744 (1990); 10.1063/1.458505 The effect of steady flow fields on the isotropic-nematic phase transition of rigid rodlike polymers J. Chem. Phys. 92, 792 (1990); 10.1063/1.458598 Concentration fluctuation of stiff polymers. I. Static structure factorThe dynamical structure factor of the solution of rod-like polymers is calculated by using a newly proposed kinetic equation. The initial decay rate of the structure factor is obtained as a power series of the scattering vector k. It is found that (i) the coefficient ofk 2 , which gives the cooperative diffusion constant, increases with concentration due to the excluded volume of rod and (ii) the coefficient ofk 4 changes sign from positive to negative. These results agree qualitatively with experiments.

The static structure factor g(k) of the concentrated solution of stiff polymers is calculated based on the generalized random phase approximation (RPA) which accounts for the nematic interaction (i.e., the interaction causing the nematic phase of stiff polymers) between the segments. The structure factor is obtained in the form of power series expansion with respect to k. The result is: (i) the correlation length ξ is independent of the nematic interaction, and is given by the conventional RPA; (ii) the sign of the coefficient of k4 changes from positive to negative as the nematic interaction is increased; and (iii) the structure factor of rigid rod, which can be calculated exactly, shows no anomaly below the critical concentration c*, but suddenly shows anomaly above c*.

Starting from a N-particle diffusion equation, the effective particle (self-) and concentration diffusion coefficients of interacting Brownian particles are studied theoretically. These two diffusion coefficients defined by distinct ways are different for interacting systems. By taking into account both potential and hydrodynamic interactions, the expression for the frequency-dependent particle diffusion coefficient exact to linear order in number density is derived. Detailed calculations of both diffusion coefficients are performed for model systems of hard spheres with a repulsive or an attractive long-range potential. The effects of potential and hydrodynamic interactions on these two diffusion coefficients are clarified. The velocity autocorrelation function is also calculated and non-Markovian behaviors are discussed.

A color-reconstruction method for electroholography is proposed in which three colored reference lights, namely, red, green, and blue light-emitting diodes, simultaneously illuminate one hologram plane. Three colored light-emitting diodes are placed at the apexes of a small right-angled triangle. Inasmuch as there is a small gap between consecutive light axes, three colored diffraction lights can be piled up at the place where a three-dimensional image is focused. In our experiment we used a high-resolution liquid-crystal display panel as a spatial light modulator with a pixel pitch of 10 microm and a resolution of 1400 x 1050. The system clearly reconstructed a colored moving image including a mixture of colors, for example, cyan, yellow, magenta, and white.

It is shown that the orientation dependent excluded volume interaction between elongated nematic molecules and the cell walls always favors the planar alignment of nematic liquid crystals. For thermotropic liquid crystals the anchoring energy of this effect amounts to several erg/cm2.

A homogeneous (planar) alignment of nematic liquid crystal on an optically uniaxial substrate, the optic axis of which is parallel to the surface plane, is considered. Based on the macroscopic theory of van der Waals forces, the contributions of the electrostatic dipolar forces and the dispersion force of the interfacial free energy between the liquid crystal and substrate are considered as functions of the angle between the optic axis of the substrate and the director of the liquid crystal.