A fuel conditioning method is applicable to common rail direct injection or unit injector system. Specifically, the method and apparatus of the present invention have applications in parallel synthesis of molecular sequence arrays on solid surfaces. A pair of intermediate strips are positioned lengthwise between the first housing and the second housing which hold together the first and second housing. suppress, or enhance hTAS2R46, hTAS2R47 and hTAS2R50 bitter taste transduction or bitter taste response. The first and second cutting faces define at least four of the cutting edges thereon, such that the cutting teeth are selectively mountable on the circular rotating element in any one of at least eight different positions, each of the positions providing a different one of the cutting edges in the operable cutting position.