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Iron was anodically oxidized in a borate‐boric acid buffer solution of pH 8.4 in the potential range extending from the active region to oxygen evolution. In the active region there appeared to be some Fe3O4 on the surface. In the passive region the iron was covered with an oxide film 10–30Aå thick, depending on the potential. The structure of the film was studied by its cathodic behavior and electron diffraction and was found to consist of an inner “ Fe3O4 ” and an outer “ γ‐Fe2O3 ” layer. The outermost part of the film had a defect structure of the general formula Fex6+·Fe2−2x3+·□x·O3 . The thicknesses of the layers and the number of defects were found to be functions of the anodic potential. The chemical reactions involved in the anodic passivation and the subsequent cathodic reduction processes are discussed.

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The anodic polarization curve, the static passive potential, and the behavior of the decay of the polarized passive potential of iron were examined in neutral boric acid/borate solutions with and without Fe++ ion addition. It was found that the passivation potential is a function of the [Fe++] and pH and corresponds to the equilibrium potential of the reaction of γ‐Fe2O3+6H++2e⇄2Fe+++3H2O . The polarized passive potential in the steady state is related to a pseudoequilibrium potential that corresponds to a higher defect concentration in the oxide surface and to a lower [Fe++] at the oxide/solution interface. The potential gradient across the film appears to be very small. The decay of the polarized passive potential on open circuit is explained as due mainly to the change in the defect‐concentration and consequently of the film composition at the oxide/solution interface either by the outward migration of iron through the film or by the reaction with Fe++ ion in solution when the latter had been added or supplied by a small amount of self‐corrosion.

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We investigated the localization of non-muscle myosin II isoforms and mono-(at serine 19) and diphosphorylated (at serine 19 and threonine 18) regulatory light chains (RLCs) in motile and non-motile MRC-5 fibroblasts. In migrating cells, myosin IIA localized to the lamella and throughout the posterior region. Myosin IIB colocalized with myosin IIA to the posterior region except at the very end. Diphosphorylated RLCs were detected in the restricted region where myosin IIA was enriched. In non-motile cells, myosin IIA was enriched in peripheral stress fibers with diphosphorylated RLCs, but myosin IIB was not. Our results suggest that myosin IIA may be highly activated by diphosphorylation of RLCs and primarily involved in cell migration. ß 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

Freezing of solutions including disaccharides (trehalose, sucrose, and maltose) has been investigated by microscopic observations of freeze-fractured replicas using FE-TEM. Three typical features were observed: the smooth surface considered as the ice crystal, fine particles as the precipitated disaccharide molecules, and remaining part as the glass state of the solution. The expanded observations of fine-particle and its distribution investigations suggested that it was larger than 10 nm in size and averaged approximately 20-30 nm in diameter. The smallest particle was estimated to include several hundred disaccharide molecules.Based on systematic observations of trehalose solutions regarding concentrations and freezing rates, we concluded that ice crystal growth was inhibited by trehalose molecules. Since the ice crystal size reduced exponentially with increase in trehalose concentration, we could control ice crystal size formed in the frozen material. The growth inhibition of ice crystals with trehalose resulted both from a reduction in the free water in the solution due to a significant hydration effect and from an enhancement of nucleation of the ice crystals.It was confirmed that trehalose was more effective than the other disaccharide solutions examined for inhibiting the growth of ice crystals.