Nonequilibrium interface equations: An application to thermocapillary motion in binary systems

Interface equations are derived for both binary diffusive and binary fluid systems subjected to nonequilibrium conditions, starting from coarse-grained (mesoscopic) models. The equations are used to describe thermocapillary motion of a droplet in both purely diffusive and fluid cases, and the results are compared with numerical simulations. A mesoscopic chemical potential shift owing to the temperature gradient, and associated mesoscopic corrections involved in droplet motion, are elucidated.     

Effect of carbon dioxide sorption on the phase behavior of weakly interacting polymer mixtures: Solvent‐induced segregation in deuterated polybutadiene/polyisoprene blends

The effect of carbon dioxide (CO₂) sorption on the lower critical solution temperatures of deuterated polybutadiene/polyisoprene blends was determined with in situ small‐angle neutron scattering. CO₂ was a poor solvent for both polymers and exhibited very weak selectivity between the blend components. The sorption of modest concentrations of CO₂, at pressures up to 160 bar, induced phase segregation at temperatures well below the binary‐phase‐separation temperature and caused an increased asymmetry in the lower critical solution temperature curve. The origin of solvent‐induced phase segregation in this weakly interacting polymer blend system was attributed predominantly to an exacerbation of the existing disparity in the compressibility of the components upon CO₂ sorption. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3114–3126, 2003     

Dead cores of singular Dirichlet boundary value problems with ϕ-Laplacian

The paper discusses the existence of positive solutions, dead core solutions and pseudodead core solutions of the singular Dirichlet problem (ϕ(u′))′ = λf(t, u, u′), u(0) = u(T) = A. Here λ is the positive parameter, A > 0, f is singular at the value 0 of its first phase variable and may be singular at the value A of its first and at the value 0 of its second phase variable. This work was supported by grant no. A100190703 of the Grant Agency of the Academy of Sciences of the Czech Republic and by the Council of Czech Government MSM 6198959214.     

The Tolerance Approach to Sensitivity Analysis of Matrix Coefficients in Linear Programming: General Perturbations

In the tolerance approach to sensitivity analysis of matrix coefficients in a linear programme, the maximum tolerance percentage characterizes the largest percentage within which selected matrix coefficients may vary simultaneously and independently while retaining the same set of optimal basic variables. While it is difficult to calculate exactly the maximum tolerance percentage under perturbations in multiple rows or columns, we show herein how it can be approximated.     

Molecular modeling of polymers. 10. Characterization of conformational transitions of poly(acrylic acid) and poly(methacrylic acid) using dyad structures

The conformational profiles of nearest side-chain neighbors, methylene-dyad structures, of poly(acrylic acid), PAA, and poly(methacrylic acid), PMA, were determined as a function of tacticity, extent of ionization, and presence of counterion. The dominant backbone conformer states are quite similar for both isotactic and syndiotactic diads in a common charge state. Thus, the overall dimensional properties of isotactic syndiotactic and atactic chains of PAA or PMA, based upon dyad interactions, are predicted to be alike for a given charge state. Significant deviations from precise t, g⁺, and g^? states are found for the dyad minimum energy conformations. The rod-to-coil and coil-to-rod transitions observed in PAA and PMA, respectively, as a function of increasing counterion concentration can be explained, to a large extent, by the conformational profiles of the corresponding dyad model structures. © 1994 John Wiley & Sons, Inc.     

Do we really need a superconducting glass model?

Muller and coworkers have introduced the concept of a superconducting glass to explain some magnetization data in highT _csuperconductors. We explain this data using conventional ideas of type-II superconductivity.     

A novel study of charged carbon clusters using a tandem Van de Graaff accelerator

A conventional tandem Van de Graaff accelerator is used to produce charged carbon cluster beams. The unique capability of the method for studying highly charged clusters unaccessible to other methods of producing cluster beams is demonstrated.     

Iterative methods for a fourth order boundary value problem

We consider a fourth order nonlinear ordinary differential equation together with two-point boundary conditions and provide a-priori error estimates on the length of the interval (b?a) so that the Picard's iterative method, the approximate Picard's iterative method and the quasilinear iterative method convergence to the solution of the problem.