Disk drive spin-up is staggered to reduce peak power requirements. A bone mounting device for fastening a joint to an artificial bone includes an expandable engagement member that fits within a cavity formed within a bone to hold the bone securely so that a surgical procedure can be performed on the joint. A dielectric layer and a protective layer are provided to cover the electrodes thereof and the surface. The thickness of the first core layer is defined based on the thickness of an unoxidized semiconductor material sandwiched between the first clad layer and an oxide film the part of which is thermally oxidized. The nozzle is disposed at the second end.