Various geophysical factors have been blamed as the cause of a rare blinding disease found in the Red Sea littora. A small expedition of the Scientific Exploration Society backed by The Royal Military College of Science in England, whose laboratories were utilised, visited the Dahlak group of islands. There it was discovered that in some areas human eyes are subjected to relatively high short ultra-violet radiation (SUVR) doses. This was true not only for total integrated ultra-violet radiation but also in the case of that proportion reflected from white coral sand especially when contaminated with salt. The day-long activities of the inhabitants, whose living depends on diving and fishing, in islands without shade, as well as the weather conditions, contribute to a complexity of circumstantial evidence strongly supporting the view that the condition known as climatic keratopathy arises from the cumulative effect on the exposed part of cornea, especially in the range discovered there -290 to 310 nm. Laboratory work was carried out on samples of topsoil on the islands and in the mainland of Eritrea. Ultra-violet sensors and detectors were used under different circumstances to augment the information. This paper amplifies the clinical paper on Dahlak blindness published in the British Journal of Ophthalmology.
Polymers such as polyethylene, polytetrafluorethylene and polypropylene may be copolymerized with acrylic acid by radiation initiation to produce copolymers which are cationic hydrogels and thus possess physical properties different to the base polymers from which they are derived. The present preliminary study was undertaken to determine whether this class of material may have potential application for use within the urinary tract. Inserts of such copolymers in sheet form (5 mm. square) and their corresponding base polymers were placed in the bladders of male Wistar rats as free floating grafts and left in situ for 3 months. Stone formation and/or encrustation occurred on 12 of the 16 radiation graft copolymers and on 9 of 11 of the corresponding base polymers. The altered physical properties of the tested acrylic acid graft copolymers appear to offer no additional resistance to encrustation although their plasticity and ability to swell in water may provide some advantages over more conventional polymeric materials.
SynopsisWe report some preliminary observations on the influence of applied pressures up to 90,000 psi on some gamma-initiated, solid state polymerizations. Four monomers have been studied: acrylamide and methacrylamide, both of which are believed to yield atactic polymer but show markedly different rates of reaction in the solid state, and some crystalline modifications of calcium acrylate and barium methacrylate, which can give rise to stereoregular polymer. The rate of polymerization of the former monomers is reduced by the application of pressure but this rate is substantially increased for the metal salts. These results are discussed with reference to the possible polymerization mechanisms.
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