Abstract: Disclosed herein are systems and methods for treating a magnesium or a magnesium alloy substrate. The system includes a cleaning composition having a pH greater than 8.5 or a solvent, and a pretreatment composition comprising an organophosphate compound and/or an organophosphonate compound. The method includes contacting a substrate surface with the cleaning composition or the solvent, and contacting the surface with the pretreatment composition. Also disclosed are substrates treated with one of the systems or methods. Also disclosed are magnesium or magnesium alloy substrates wherein, between the air/substrate interface and 500 nm below the air/substrate interface (a) oxygen and magnesium are present in a combined amount of at least 70 atomic %; (b) carbon is present in an amount of no more than 30 atomic %; and/or (c) fluoride is present in an amount of no more than 8 atomic %, wherein atomic % is measured by XPS depth profiling.

Abstract: Disclosed is a wireless surround sound speaker system wherein a transmitter broadcasts a variety of FM signals that correspond to the individual speaker channels commonly found in a surround sound system. Receivers, individually equipped with signal receiving, conditioning and amplification components, are configured to receive any one of the broadcast signals in a remote location and are used to drive a conventional loudspeaker in that location. Powered by wall socket or via DC battery packs, the receivers, used in conjunction with the transmitter, provide surround sound capabilities without the need for complex and difficult wiring.