Characterisation of the interface of sputter-deposited copper coatings on nitrogen plasma-treated carbon substrates.

The adhesion of copper coatings to carbon substrates is very poor, because of lack of diffusion or reaction between the constituents. Because there is technological interest in enhancing the adhesion and improving the interface between copper and carbon, plasma treatment of the carbon substrate was employed in this study. For modification of the carbon surface a nitrogen plasma was used. It was confirmed by pull-off tests that the strength of adhesion of the copper coating can be improved by a factor of more than 10 by plasma pretreatment, even after treatment for a very short time (1 min). To obtain more information about the mechanisms of the processes occurring at the interface SIMS investigations were performed on samples which had been treated for different times (between 1 and 60 min). These measurements confirmed that nitrogen is located on the interface. With increasing pretreatment time the amount of nitrogen detected on the interface increased. Besides characterisation of as-deposited samples, another focus was to study the mechanisms of diffusion of nitrogen if the samples are heat treated at 500 degrees C.

Structural changes of hair after incorporation of the proline analogue L-azetidine-2-carboxylic acid. A model of hair disease by alteration of primary structure.

In order to correlate biochemical changes of the hair with physical properties we present a model for the examination techniques. L-azetidine was incorporated into the hair keratin complex and the resulting mechanoelastic properties were determined using the ultramicrohardness testing system on scanning electron microscopy. Structure was investigated by X-ray diffraction and incorporation of L-azetidine was detected by thin-layer chromatography. This system could possibly be introduced for examination of hair changes in humans. 8 white mice, 3 weeks of age, were given L-azetidine-2-carboxylic acid in water (0.1 g/100 ml) as only source of fluid over a period of 5 weeks. They had free access to dry mouse cake only. 8 animals of the same strain, who had free access to tap water and mouse cake and were kept under the same conditions, served as controls. After 5 weeks, the animals were sacrificed and hair was obtained for analyses. 2 dimensional thin-layer chromatography of hair hydrolyzed with 6N HCl at 105 degrees C for 12 hours revealed 2 additional spots in the chromatographic pattern in the experimental animals in comparison with the control group. 1 of the spots was identified as L-azetidine-2-carboxylic acid, while the second spot was possibly a degradation product of L-azetidine on acid hydrolysis at a high temperature. Hair of the animals was put into Mark capillaries and subjected to X-ray diffraction, which showed a markedly disordered orientation of keratin. Impression studies using scanning electron microscopy revealed a remarkably reduced elasticity of hair with incorporated L-azetidine. These findings may be explained on the basis of qualitative or quantitative changes in the helical structure of the keratin complex of hair, which is responsible for the elastic properties, whereas the globular matrix is responsible for the firmness of the hair.