Because the heterogeneous and particulate natures of commercial electrodes are not convenient for controlled SPM investigations, study relies on model electrodes that are more practical from an experimental standpoint. At the most basic level, these models are large single crystals of the compounds of interest. Closer to real electrodes are polycrystalline thin films and model composite electrodes that incorporate the fillers and binders used in commercial cells. Thus, a second important objective of this project is to develop synthetic routes to produce the desired model systems, in particular single crystals of transition metal oxide cathodes. Paradigm for Active Polymeric Materials Actin is a major cytoskeletal protein of eukaryotic cells, which binds and hydrolyses ATP and self-assembles to form long helical polymeric filaments.
Actin filaments are very dynamic biopolymers.
In contrast to most synthetic polymers that are held together by strong covalent bonds, the actin subunits are held together by relatively weak noncovalent bonds. This molecular vitalism is essential for its function in biological systems because it enables actin filaments to transduce chemical energy stored in ATP into mechanical energy to produce physical forces. Polymerizing gels of actin filaments are capable of exerting significant mechanical forces, used by eukaryotic cells and bacteria to change shape or to move. A well-defined biochemical model system for actin propulsion is the bacterium Listeria monocytogenes . Recently the motility of this bacterium has been reconstituted using purified proteins and a bacterial-free system.