In one embodiment, a separation layer and a wiring layer are formed in order on a supporting substrate. The subscriber station includes a receiver configured to receive signals from a base station. In some embodiments, the first ion guide may be an ion funnel and the second ion guide may be a linear multipole device. The finger wheels are mounted such that bottom edges thereof are maintained at a substantially constant vertical position relative to the ground by at least one depth control wheel rolling along the ground on the first path cleared by the front finger wheel. Dispersions of these biocompatible cerium oxide nanoparticles exhibit self-life well in excess of one year, and may be used to prevent andor treat disease or injury, such as oxidative stress related diseases and events.