A control circuit for a controllable electric solenoid valve of a brake system of a motor vehicle is described, in which the actual values of a controlled variable ), e. A variety of types of related words can be used, such as synonyms and translations, and the related words can be determined in a variety of ways. The present invention also relates to a method of influencing the degradation rate of a crosslinked polymer or hydrogel, comprising the step of incorporating uncharged acrylamides into the crosslinked polymer or hydrogel. The elastic material 3 has elastic materials 31, 32 and 33 having hardness which becomes larger as they come closer to the main part 2.