Narrow Results

In this article we use a lattice-Boltzmann simulation to examine the effects of shear flow on an equilibrium droplet in a phase separated binary mixture. We find that large drops break up as the shear is increased but small drops dissolve. We also show how the tip-streaming, observed for deformed drops, leads to a state of dynamic equilibrium.

The ultraviolet/visible photon transmission technique was applied to study the phase diagram of a mixture of 4-ethoxy-4′-(6-vinyloxyhexyloxyl) azobenzene (VE), a smectogen, and 4-hexoxy-3′-methyl-4′-(6-acryloyloxyhexyloxy) azobenzene (AH), which by itself exhibits no liquid crystalline behavior. It has been found that the N-Sm-A phase line terminates at either a tricritical point at about X_VE = 0.9, where X_VE is the weight percentage of VE in the binary mixture, or at least at a tricritical region 0.9 < X_VE < 1 within the experimental resolution. For X_VE = 1 the nematic phase region is not large enough to drive the transition second-order. It is found that the value of the critical exponent β for X_VE = 0.9 is consistent with the tricritical value.

The self-consistent mode-coupling theory (MCT) has been used to analyze the heterogeneous dynamical nature of a binary supercooled liquid. The non-Gaussian behavior is studied by analyzing the self part of the Van Hove correlation function, G^s(r, t). From the analysis of the single particle dynamics we identify a fraction (ϕ_M) of particles which are dynamically more active and find that ϕ_M increases as the temperature is decreased. This behavior is qualitatively similar to the computer simulation studies of the same system.

We investigate the pattern formation of a binary polymer mixture in the presence of chemical reaction A ⇌ B and with the inclusion of mobile particles under a modulated pinning potential. The presence of particles with a preferential attraction for one component of the mixture breaks the isotropy of the bulk phase-separating process and controls the orientational ordering of structures. On the other hand, the chemical reaction can change the relative volume of A and B components, leading to the formation of a wide variety of morphologies. We find that due to the competition among the chemical reaction, phase separation and externally-driven effect, some unusual ordering structures can be realized. The results may provide some important insights into designing novel ordering morphologies such as microporous structures and quantum dots.

In this work we report theoretical and numerical results on convection in a viscoelastic binary mixture under rotation. Instability thresholds for stationary convection are calculated. We obtain explicit expressions of convective thresholds in terms of the control parameters of the system for oscillatory convection. Finally, we analyze the stabilizing effect of rotation on instability thresholds for aqueous DNA suspensions.

We report both theoretical and numerical results on convection for a binary magnetic mixture under rotation. We focus on the stationary convection for idealized boundary conditions. We obtain explicit expressions of convective thresholds in terms of the control parameters of the system. Close to bifurcation, the coefficients of the corresponding amplitude equation are determined analytically. The effect of the magnetophoresis and Kelvin force are emphasized and, finally, the nature of the bifurcation is discussed.

This paper is devoted to a newly proposed subject regarding the association processes from a single chain binary mixture. A test system was developed for 36 binary mixtures to evaluate the mean association probabilities. A methylene group added to the short hydrophobic chain is four times more effective on the mean self-association probability h₁₁ than a methylene group added to the long hydrophobic chain. As far as this comparing effect is concerned, this is twice more effective for the mean self-association probability h₂₂.

Simulation results of dense granulates with particles of different sizes are compared with theoretical predictions concerning the mixture pressure. An effective correlation function is computed which depends only on the total volume fraction and on the dimensionless width of the size-distribution function. From simulation data of elastic and weakly dissipative systems, one can predict how much disorder (size-dispersity) is necessary to avoid ordering effects due to crystallization. Finally, a global equation of state is proposed, which unifies both the dilute, disordered gas/fluid and the dense, solid regime.

We model the mechanical behavior of diatomic crystals in the light of mixture theory. Use is made of an approximation method similar to one proposed by Signorini within the theory of elasticity, by supposing that the relative motion between phases is infinitesimal. The constitutive equations for a mixture of elastic bodies in the absence of diffusion are adapted to the partially linearized case considered here, and the representation theorems for constitutive fields are applied to obtain the final expression of dynamical equations in the form which appears in theories of continua with vectorial microstructure. Comparisons are made with results of lattice theories.

Simulation results of dense granulates with particles of different sizes are compared with theoretical predictions concerning the mixture pressure. An effective correlation function is computed which depends only on the total volume fraction and on the dimensionless width of the size-distribution function. From simulation data of elastic and weakly dissipative systems, one can predict how much disorder (size-dispersity) is necessary to avoid ordering effects due to crystallization. Finally, a global equation of state is proposed, which unifies both the dilute, disordered gas/fluid and the dense, solid regime.