The effect of ultrasounds on the surface of metallic plates with cubic faced centered (Al, Ag, Cu) or hexagonal (Zn) structure was studied. Treated surfaces were strongly attacked: a micrometric roughness and a superficial oxidation (characterized by roughness measurements and scanning electron microscopy) were induced. X-ray diffraction analyses showed a preferential reorientation of the maximum density planes for both crystallographic structures.

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The crystal structures of a series of compounds containing protonated benzimidazole functions are reported. Hydrogen bonds are always seen in the plane of the benzimidazole but, in opposition to our previous work, stacking interactions between the benzimidazole cations are not invariably observed. In zwitterionic benzimidazole carboxylic acid compounds, a gauche conformation is often adopted which allows a Coulombic attraction between carboxylate and benzimidazolonium functions.