Abstract: A cleaning tank defining therein a cleaning chamber adapted to receive an article to be cleaned and having an upper opening for carrying the article into and out of the cleaning chamber, a plurality of small holes provided in the bottom wall of the cleaning chamber and communicated with an outlet port, and at least one inlet port for introducing a cleaning liquid into the cleaning tank and into the cleaning chamber only through the upper opening thereof.

Abstract: A plate roofing material is divided into an exterior portion which is exposed when a roof is covered with a plate roofing material and an overlap portion which is concealed under an exterior portion of a plate roofing material superimposed on the overlap portion of the plate roofing material. At least one longitudinal groove is formed in the surface of the exterior portion. The longitudinal groove has wide side surface parts alternating with narrow side surface parts with sidewalls formed of a plurality of stepped portions. The longitudinal groove has a linear bottom part having an approximately constant depth and is approximately V-shaped in cross section.

Abstract: Disclosed is a useful method of removing a charge from an electrophotographic photoreceptor provided with insulation layers on its surface by radiating light containing a minimum of 6,000 angstroms of peak wave length onto said photoreceptor simultaneously with a corona discharge. To realize this, a filter is applied so that light containing a minimum of 6,000 angstroms of peak wave length can be generated.