A method of cleaning a surface which comprises the step of applying an aqueous cleaning solution to the surface wherein the active cleaning ingredient of the aqueous solution consists essentially of a lignosulfonate. The electronic printing system includes a memory card interface for receiving the removable memory card, the removable memory card having stored thereon a plurality of digital image files and a print utilization file, wherein the print utilization file including the names of at least two digital image files stored on the removable memory card to be printed. The first and second amplification units are operable with separate loads, in parallel driving a common load, or across a bridge-tied-load. A superconducting power cable including a tubular copper former defining a cooling duct about which superconducting tape is helically laid in two layers of either the same or opposite hand. The phosphor of the present invention has the empirical formula:. A characteristic value is then selected for each time variable interval and each extracted signal to generate a characteristic sample profile, comprising one or more characteristic values as functions of respective time variable intervals and respective mass variable intervals.