One aspect of the present subject matter relates to an implantable medical device. The power strip includes at least one polarized receptacle and a conductor. The separate streams may be combined to produce a gradient, such as a concentration gradient or shear gradient. The butt end portion is pre-arranged to be the desired pre-selected portion weight or at least an acceptable pre-selected portion weight. The method is useful for generating 5\u2032- and 3\u2032-tagged DNA fragments for use in a variety of processes, including processes for metagenomic analysis of DNA in environmental samples, copy number variation analysis of DNA, and comparative genomic sequencing, including massively parallel DNA sequencing.