A method for reducing the permeation rate of a permeable species through a polymeric material includes identifying a solubility-increasing species in the polymeric material having a reversible affinity for the permeable species, and removing or altering at least a portion of the solubility-increasing species in the polymeric material. The load, applied to said second auxiliary arm is transmitted to the indenter carrying arm of the reference stress structure of the tester by unrestrained abutment of a rolling bearing solidly mounted on one of the two arms on a surface of the other arm. a non-volatile memory component, within the cell which can be programmed to provide the SRAM cell with a definitive asymmetry so that the cell always starts in a particular state. %, in relation to the weight of the salt, of at least one compound of general formula I or the corresponding alkali metallic salts or alkaline-earth metallic salts thereof or ammonium or phosphonium salts.