Calcium phosphate coatings on steel, obtained by the plasma-spray technique, were examined by x-ray diffraction in order to get some information on their crystallographic structure and crystallinity. Surface roughness values were also determined. These coatings are of interest for hip-prosthesis materials in particular.

Plasma-spraying of metallic implant surfaces is an established method for the application of hydroxylapatite (HA) coatings. Carbon fibre reinforced thermoplastics show different thermal and mechanical properties, compared with titanium substrates. In this paper first results of the influence of the established coating method on carbon fibre reinforced thermoplastics are presented. First investigations of the tensile adhesion strength, tested with a newly developed testing device, showed that the adhesion between the HA coating and the carbon fibre reinforced polyetheretherketone (PEEK) composite is very low. Macromechanical bending tests showed a change to initial tensile instead of compression failure of the coated composite substrate. Micromechanical bending tests in a scanning electron microscope (SEM) hot tensile stage (Raith GmbH) revealed crack propagation within the ceramic coating and in the coating-substrate interface before the total failure of the composite substrate occurred.

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Recent studies of the physical chemistry of the antihistamines2 have been valuable in the correlation of the pharmacological properties of such compounds with certain of their physical properties. It is thought that the ionic radius of an antihistamine may be important in its biological efficiency. This paper describes two techniques which were used to determine the ionic radius of the Histadyl and Pyrilamine cations. The radii obtained by the two methods for Histadyl are in close agreement; however no satisfactory radius could be obtained by the apparent molal volume method for Pyrilamine. Experimental Materials.-Histadyl (X,N-dimethyl-N',2-thenyl-N'-o:pyridylethylenediamine hydrochloride), which was furnished by Eli Lilly and Co., carried the manufacturers specifica-Department