This invention relates to high molecular weight block copolymers of -caprolactone and -lauryl lactam prepared by sequential bulk polymerization using a mixture of at least one anionic polymerization initiator and optionally at least one co-initiator. The method for fabricating a reinforced concrete beam generally includes the steps of positioning a plurality of rebars parallel with respect to each other to form the internal reinforced frame of the beam. The recording layer is substantially composed of Bi and O, and the ratio of the number of the O atoms to the total number of Bi and O atoms in the recording layer is 63-73%. A method is provided for mounting an escape filter device system. Lower programming results from the SSI method of programming and a compact memory cell size exists. Also, a method of controlling the growth of microorganisms using a biocide prepared by the method of the present invention is disclosed.