An apparatus for grooming cats which includes a source of food located in an enclosure and a grooming brush assembly forming an adjustable aperture which is mounted between a portal formed in the enclosure and the source of food. As a result of the chemical reaction and diffusion of elements, one can change a heated portion of the layered structure to a semiconductor or an insulator, depending on the temperature to which the portion is heated. An insulating film is deposited on the entire top surface of the substrate, and a resist film for exposing an area stretching over the active area, a part of the isolation and the gate protection film is formed on the insulating film. A guide portion of the inner surface is tapered in an axial direction of the bore such that dimensions of the bore increase towards a central region of the bore, and the bearing cage further includes a plurality of conduits providing fluidic communication between the inner surface of the bearing cage and the outer surface of the bearing cage.