An electron emission device includes a substrate, cathode and gate electrodes placed on the substrate in an insulated manner, and electron emission regions electrically connected to the cathode electrodes. SERS substrates are prepared by combining a colloidal gold monolayer with a solution containing a source of metal ions and a reductant such as NH2OH. In a method aspect of the present invention, a sedative-hypnotic drug is administered to a patient through an inhalation route. The fluidic network contains a magnetic particle andor a signal particle. These compounds are capable of improving the antiwear and lubricity properties of a low sulphur fuels, especially diesel fuels, when compared with the performance of the same fuel in the absence of such compounds.