The described apparatus has utility as a doctor on a paper machine, as a drying element in an aircap dryer and as a sealing element in such a dryer. It involves a foot portion having an outer surface generally conforming to the curvature of the cylinder surface on which it is used. It is resiliently supported in close juxtaposition to the cylinder surface so that a gap diminishing in thickness towards one longitudinal edge of the foot portion is provided. At least two rows of nozzles communicate through the foot portion in order to project pressurized air into the gap. Each nozzle is angled relative to three orthogonal planes, one of which is tangent to the cylinder surface at the point where the nozzle axis meets the surface, another of which is parallel to the longitudinal edge of the foot portion. The flow from the nozzles is such as to support the foot portion and to seal the support flow from any disorganized flows. The jetting air will tend to aid in doctoring a paper sheet from the cylinder surface or to dry a paper sheet passing thereunder or to seal an opening from the passage of air therethrough if the opening is defined by a cylindrical surface.