Particle-Size-Exclusion Clogging Regimes in Porous Media.

From observations of the progressive deposition of noncolloidal particles by geometrical exclusion effects inside a 3D model porous medium, we get a complete dynamic view of particle deposits over a full range of regimes from transport over a long distance to clogging and caking. We show that clogging essentially occurs in the form of an accumulation of elements in pore size clusters, which ultimately constitute regions avoided by the flow. The clusters are dispersed in the medium, and their concentration (number per volume) decreases with the distance from the entrance; caking is associated with the final stage of this effect (for a critical cluster concentration at the entrance).

Relationship between ultrastructure and biomechanical properties of the knee meniscus.

The purpose of this study was to determine the biomechanical properties of the knee meniscus and to relate them to its ultrastructure. The knee joint menisci are semicircular, fibrocartilaginous structures interposed between the femoral and tibial condyles. For a long time, they were considered to be embryologic vestiges.

Tensile strength of cranial pia mater: preliminary results.

Object: The goal of this study was to determine the tensile strength of cranial pia mater.

Methods: Samples of isolated bovine cranial pia mater were subjected to quasistatic traction to evaluate its tensile strength. The experimental curves of physiological deformation that were obtained can be subdivided into three parts that represent different mechanical properties: the nonlinear initial part of the curve demonstrates increasing stiffness, followed by a quasilinear pattern of elastic behavior, and finally a negative relationship (slope) between force and elongation, which characterizes a progressive deterioration.

Dynamic stiffness and damping of porcine muscle specimens.

The aim of this study was to quantify the mechanical properties of the muscles of the buttock, using dynamic compression (5-->30 Hz). Tests were conducted in vitro on porcine muscles, using a lever arm device, which applied a dynamic load onto cylindrical samples. A two-parameter viscoelastic model allowed the calculation of stiffness and damping of the samples with respect to frequency.