New and improved compounds for use in diagnostic imaging or therapy having the formula M\u2014N\u2014O\u2014P\u2014G, wherein M is an optical label or a metal chelator, N\u2014O\u2014P is the linker, and G is the GRP receptor targeting peptide. The method is employed in the cloning of the MseI restriction-modification system. The present invention also provides apparatus for processing organic waste in divided solid andor liquid form by incineration and vitrification, which apparatus is suitable for implementing said method. Set between an inlet of the solenoid valve and an inlet of the pressure regulator is a control volume designed to contain an amount of fuel such as to guarantee an adequate flow of fuel in an area corresponding to the inlet of the solenoid valve.