Rigorous upscaling of the infinite adsorption rate reactive flow under dominant Peclet number through a pore

In this paper we present a rigorous derivation of the effective model for enhanced diffusion through a narrow and long 2D pore. The analysis uses the anisotropic singular perturbation technique. Starting point is a local pore scale model describing the transport by convection and diffusion of a reactive solute. The solute particles undergo an adsorption process at the lateral tube boundary, with high adsorption rate. The transport and reaction parameters are such that we have large, dominant Peclet number with respect to the ratio of characteristic transversal and longitudinal lengths (the small parameter ). We give a formal derivation of the model using the anisotropic multiscale expansion with respect to . Error estimates for the approximation of the physical solution, by the upscaled one, are presented in the energy norm as well as in L ^∞ and L ¹ norms with respect to the space variable. They give the approximation error as a power of and guarantee the validity of the upscaled model through the rigorous mathematical justification of the effective behavior for small . The research of A. Mikelić and C. Rosier was partially supported by the GDR MOMAS (Modélisation Mathématique et Simulations numériques liées aux problèmes de gestion des déchets nucléaires) (PACEN/CNRS, ANDRA, BRGM, CEA, EDF, IRSN) as a part of the project “Changements d’échelle dans la modélisation du transport multiphasique et réactif en milieux poreux : application aux milieux fracturés et aux argiles”.     

Analysis of Differential Equations Modelling the Reactive Flow through a Deformable System of Cells

A system of model equations coupling fluid flow, deformation of solid structure and chemical reactions is formulated starting from processes in biological tissue. The main aim of this paper is to analyse this non-standard system, where the elasticity modules are functionals of a concentration and the diffusion coefficients of the chemical substances are functions of their concentrations. A new approach and new methods are required and adapted to these nonlinearities and the transmission conditions on the interface solid–fluid. Strong solutions for the initial and boundary value problem are constructed under suitable regularity assumptions on the data, and stability estimates of the solutions with respect to the initial and boundary values are proved. These estimates imply uniqueness directly. The approach of the paper can be used in more general problems modeling reactive flow and transport and its interaction with elastic cell structures. In a forthcoming paper the approach of this paper is used for getting the upscaled system modeling reactive flow through biological tissue on the macroscopic scale, starting from a system on the cell level.     

Gravitational repulsion of spherical domain walls

We consider the disagreements in gravitational properties of planar and spherical domain walls (bubbles). We argue that if the spherical domain walls are described by the same equation of state as the planar walls are, then they also exhibit gravitational repulsion just as the planar walls are assumed to do. In the thin-wall approximation we show the existence of the solution of Einstein equations with negative gravitational mass of bubbles and the reversed direction of time flow on the shell. The equilibrium radius and critical mass of such objects are found for realistic models.     

Designing new isomorphic fluorescent nucleobase analogues: the thieno[3,2-d]pyrimidine core

A convergent approach for a family of fluorescent nucleosides is described. It relies on thieno[3,2-d]pyrimidine-2,4(1H,3H)-dione that serves as a core heterocycle. This condensed pyrimidine is converted into an emissive pyrimidine nucleoside analogue by N-glycosylation and into an emissive purine nucleoside analogue by C-glycosidation at the thiophene's beta position. The design principles of this archetypical system are outlined together with the syntheses and photophysical properties of the resulting nucleosides.     

Design, synthesis, and spectroscopic properties of extended and fused pyrrolo-dC and pyrrolo-C analogs

The syntheses of four fluorescent nucleoside analogs, related to pyrrolo-C (PyC) and pyrrolo-dC (PydC) through the conjugation or fusion of a thiophene moiety, are described. A thorough photophysical analysis of the nucleosides, in comparison to PyC, is reported.     

Dispersibility and characterization of polyvinyl alcohol–coated magnetic nanoparticles in poly(glycerol sebacate) for biomedical applications

Journal of Nanoparticle Research - Triggered by experimental observations of nanometer-sized Ni precipitate motion in a La2O3 matrix, the migration and morphological evolution by interface...