G K Ambady
Articles written in Proceedings – Section A
Volume 49 Issue 3 March 1959 pp 136-143
When collagen fibres are treated with acidic and alkaline solutions of inorganic salts, oriented crystallisation of the salts takes place inside the protein fibre. The treated fibres give X-ray diagrams which closely resemble single crystal rotation photographs. A direct relationship has been established between the crystal parameters lying parallel to the fibre axis and the axial repeat of collagen. Oriented crystallisation does not occur in neutral solution. In both acidic and alkaline solutions the orientation improves with swelling. The chemical treatment is found to have little effect on collagen itself in most of the salts.
Volume 63 Issue 1 January 1966 pp 26-38
Small angle scattering patterns have been photographed from cotton (and viscose) fibres containing deposits of silver, mercuric sulphide, lead sulphide, lead chromate and lead iodide. These patterns have shown that deposits of the cubic crystals are nearly isodiametric and randomly oriented. On the other hand, particles of lead chromate and lead iodide are elongated, with the longer direction tending to be oriented along the fibre axis. These conclusions are in agreement with evidence on orientation secured from wide-angle diffraction. In the case of the randomly oriented deposits, extensive measurements have been made of the angular dependence of equatorial scattered intensity. Distributions of particle size have been computed which will synthesize back the scattered intensity. Some limitations of such calculations have been pointed out. It has been concluded, however, that the majority of particles are crystallites with dimensions of 200 Å or less. There are a few particles with very much larger dimensions. These may be polycrystalline aggregates which are lodged in the fibre lumen rather than in cellulosic substance.