Abstract: An electrophotographic photoreceptor for use in electrophotography having a photosensitive layer on an electrically conductive substrate. A fluorine-containing lubricating layer is further place upon the photosensitive layer. The fluorine-containing lubricating agent is selected from perfluoroalkyl polyether or its derivatives.

Abstract: An electrophotographic photoreceptor for use in positive charging electrophotographic machines is disclosed, comprising an electrically conductive substrate having thereon a charge transporting layer, a charge generating layer, and a low resistance surface protective layer, in that order, wherein a squarylium acid derivative having an asymmetrical structure represented by the formula (I): ##STR1## wherein R.sub.1 and R.sub.2 may be the same or different and represent a --CH.sub.3 group or a ##STR2## group (wherein Y represents a halogen atom), and X.sub.1 and X.sub.2 may be the same or different and represent a hydrogen atom, an --OH group or a halogen atom, is dispersed in said charge generating layer.

Abstract: A noise reducing apparatus is disclosed, comprising a lens-type hollow body consisting of a plurality of inclined hollow tubular passages. The lens-type hollow body has a plane incident surface and a curved emission surface and the length L.sub.2 of the hollow tubular passage is optimized in accordance with relevant dimensional parameters of setting of the lens-type hollow body in a sound field, to reduce noise from a spot sound source efficiently.

Abstract: A noise reducing apparatus in the form of a hollow body comprising two or more passage groups consisting of a plurality of passages. The length of each passage is determined such that the sound waves emitted from the passages of the adjacent passage groups form plane waves which are shifted by a half wavelength so that plane waves interfere each other. The apparatus can be secured to an opening of construction and reduce the level of sound pressure from a sound source without any closed shield construction surrounding the sound source.