Abstract: An air-fluidized bed for therapeutic use of the type comprising a tank filled with a particulate material through which passes an upward flow of gas.According to the invention, particles of spherical shape, with a density higher than that of the particulate material, and which have a greater biochemical activity than the particulate material, are introduced in the tank.Application: control of the bactericidal activity of an air-fluidized bed.

Abstract: A tennis ball conforming to the 1968 regulation of the International Federation of Lawn Tennis comprises a hollow elastic core and an improved cover bonded to the core by an adhesive mixture. The cover has a specific weight less than 0.22 g/cm.sup.3 and includes a proportion of relatively thick monofilament fibers such that the percentage-weighted average denier size of all fibers in the cover is at least 18. The cover improves the playing characteristics and the effective life of the ball.

Abstract: A racket for tennis and similar games in which the density of the strings in the central part of the strung surface is increased by incorporting a middle zone formed of a continuous length of stringing material, in which zone the strings are arranged in a pattern such that, at one of their ends, an adjacent pair of strings is immobilized relative to the frame at a common fixing point, while at their respective other ends, the strings are affixed to different fixing points. The pairs of strings having a common fixing point are not directly interconnected at the common fixing point, i.e., a path between one string affixed to a fixing point to which a second string is also affixed cannot be traced between the first string and the second string without passing through another fixing point. Only one interconnecting length of stringing material extends between adjacent fixing points.

Abstract: High performance one-piece solid molded polyurethane vulcanizate golf club heads having a unitary body including the entire front striking face and exhibiting specific properties by virtue of the vulcanizate; and golf clubs comprising the combination of said heads each with a golf shaft.

Abstract: A racket for tennis and other similar games, comprising a sensibly oval or pear-shaped stringing surface and an auxiliary element for maintaining the strings in a median plane at determined places, in which at least some strings are wound simultaneously around the frame and around the said auxiliary element.