Abstract: A prosthetic patellar component is provided which has a fixation part adapted to be secured to the bone of the patella and an articulation part defining a surface for replacing the femoral facet of the natural patella, with these parts being mutually engageable in such a manner as to allow rotation between them about a medio-lateral axis relative to the surface which replaces the femoral facet.

Abstract: This invention relates to a foamable silicate composition comprising (a) one or more alkali metal silicates, (b) a blowing agent, (c) a hardener which can be an acetate or a formate ester of a di-polyhydric alcohol or a polyoxyalkylene glycol and (d) a surfactant having a hydrophilic-lypophilic balance of at least 8. The formulations are readily produced by mixing the components, are pourable, pumpable and sprayable, and give rise to foams of excellent compressive strength and thermal insulation properties under ambient conditions.

Abstract: A method and apparatus for welding together two metal workpieces, at least one of which has thereon a coating material which enters a fluid or visco-elastic phase at a temperature below the melting temperature of the workpieces, the method comprising the steps of subjecting the workpieces to a preliminary preparative treatment at a zone to be welded and thereafter applying (preferably be means of a high-energy beam such as a laser beam) sufficient heat to the workpieces at the weld zone to effect there the welding together thereof, wherein the preliminary preparative treatment comprises preheating the workpieces to the said lower temperature and pressing them together, at the zone to be welded with a force sufficiently great to expel coating material from between the workpieces at the weld zone. thereby to improve the quality of the subsequent weld.

Abstract: A spray apparatus for the treatment of a harvested crop, the apparatus including a high voltage electrostatic spray head, a sprayhood surrounding the sprayhead and having an aperture opposite the sprayhead and insulating means to suspend the sprayhood with the aperture adjacent a region of a conveying path to establish and maintain the sprayhood covering said region of said conveying path, the sprayhood having on the outside an insulating cover and inside the cover an extensive insulated electrode extending around and above said aperture, the electrode being energizable in operation to a potential similar to that applied to the sprayhead, whereby the support means and electrode together permit the application of an electrostatically charged spray from the sprayhead in a controlled manner throughout said region of the conveying path under the sprayhood to a quantity of crop conveyed past on the conveying path in a regular manner.