Ligand-modified poly oxo-hydroxy metal ion materials and their uses are disclosed, in particular for nutritional, medical, cosmetic or biologically related applications for example for the treatment of a deficiency related to a component of the material or for the removal of an endogenous substance capable of binding to the material. Structural fiber layers are used to form at least a first preform portion that is to constitute the fiber reinforcement of the brake disk core, while the or each preform portion that is to constitute the fiber reinforcement of a friction portion of the brake disk is constituted by a felt, at least in its portion adjacent to the friction face. Common design methodologies for the square root velocity profile, linear velocity profile and regulatorestimator control system designs can be migrated from the current mode architecture to the voltage mode architecture. Reaction elements are mounted on each of the carts.