The present invention relates to anthraquinone derivatives which act as a fluorophore, to a process for producing said anthraquinone derivatives and their use as fluorophores for staining membranes in live or fixed cells. The area has a portion which is formed by removing a substance, contained in the at least one of the lower electrode layer and the upper electrode layer during formation thereof, after the at least one of the lower electrode layer and the upper electrode layer has been formed. A shaft extends through the fluid pump and the vacuum pump. In yet another position, the stop acts as a workpiece guide, especially useful for supporting crown molding during cutting.