An independently controllable transmission mechanism with an identity-ratio series type includes a first planetary gear train and a second planetary gear train mechanically connected therewith. The corresponding magnetic circuit comprises a yoke with only two pole pieces. The first side plate includes a plate member and an annular member. Preferably, at least one of the rolls is heated to a pre-selected temperature. A dielectric is on the conductive element and has an inner surface defining an upper portion of the sidewall. The present invention also provides a method for making the colloidal nanosilver solution.