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When a biological tissue is subjected to a mechanical load, an electrical potential gradient is generated. Such potential gradient is associated with the flow of charged particles through a matrix with fixed charges. A deformation of the matrix causes a fluid flow relatively to the solid matrix. This fluid flow tends to separate the freely moving ions in the fluid from the oppositely charged articles, that are attached to the matrix. In this way, an electrical field is created collinear to the fluid flow. This results in an electrical potential. A similar effect appears when charged particles start moving because of a chemical load. In this snrdy, uniaxial confined swelling and compression experiments were performed on a hydrogel that mimics the behaviour of biological tissues. The deformation of the sample and the electrical potential difference over the sample, caused by varying mechanical and chemical loads, were measured successfully.

Salt weathering is one of the major causes of deterioration of buildings and monuments. We have determined the underlying moisture and ion transport within a representative building material by measuring the time evolution of NaCl saturated samples during one-sided drying with Magnetic Resonance Imaging. The obtained NaCl concentration profiles reflect the competition between advection to the surface and redistribution by diffusion. By representing the measured moisture and NaCl profiles in a so-called efflorescence pathway diagram (EPD) also information about the crystallization process is obtained. The pathways followed in the EPDs indicate that for historical objects in general crystallization at the surface cannot be avoided, when evaporation cannot be prevented.

In this paper we discuss a pore scale model for crystal precipitation and dissolution in porous media. We consider weak solutions in general domains and dissolution/precipitation fronts in thin strips. The latter yields an upscaled transport—reaction model.

Compact bone is a well-organised, multi-level porous structure. Strain-derived fluid flow likely steers the activity of cells within the bone matrix, which in turn orchestrate the concerted activity of bone resorbing and bone forming cells at the surface. We present a model of the strain-driven bone remodelling proces, which could explain the mechanically optimised structure of compact bone.

Cancellous bone is a porous type of tissue mainly found near the ends of long bones and in vertebral bodies. In long bones, it distributes the mechanical loads from the articular surfaces to the cortical shaft, whereas in vertebral bodies it is the main load-carrying constituent. Bone fractures due to conditions such as osteoporosis usually occur in cancellous bone regions. Diseases in the skeleton, such as osteoarthritis, might be related to the mechanical properties of the subchondral bone under the affected cartilage and that of the cancellous bone supporting it. Hence, the mechanical quality of cancellous bone is an important parameter for bone fracture risk and integrity.

A method of data analysis for a set of elastic constant measurements is applied to data bases for wood and cancellous bone. For these materials the identification of the type of elastic symmetry is complicated by the variable composition of the material. The data analysis method permits the identification of the type of elastic symmetry to be accomplished independent of the examination of the variable composition. This method of analysis may be applied to any set of elastic constant measurements, but is illustrated here by application to hardwoods and softwoods, and to an extraordinary data base of cancellous bone elastic constants. The solid volume fraction or bulk density is the compositional variable for the elastic constants of these natural materials. The final results are the solid volume fraction dependent orthotropic Hooke's law for cancellous bone and a bulk density dependent one for hardwoods and softwoods.