Abstract: A method is described for local etching of surfaces. The method includes the steps of providing a surface, providing an etchant, and providing a device for supplying and extracting the etchant. The device contains two cylindrical lines of different cross-sectional areas, of which the cylindrical line with the smaller cross-sectional area is guided inside the cylindrical line with the larger cross-sectional area. An etchant is fed through the inner line to the region of the semiconductor wafer that is to be etched, and the etchant that spreads out beyond the region of the surface that is to be etched is extracted through the outer line. The cross-sectional area of the outer line is less than or equal to the area of the region of the surface which is to be etched.

Abstract: Hydraulic motor vehicle braking system with wheel slip controller, comprising a brake pressure applicator (8), which consists of a pedal-activated vacuum brake booster (18) and a main brake cylinder (19) and is connected via a brake line (14) to at least one pair of wheel brakes (2, 3), and a pump (1) connected to the brake line (14) for conveying pressure agent from the brake pressure applicator (8) in the direction of the wheel brakes (2, 3) during wheel slip control, and at least one pressure modulation valve (16, 16′) installed downstream in the brake line (14) to vary the brake pressure in the wheel brakes (2, 3) during the wheel slip control process.