Methods and apparatus for decreasing a density of a downhole fluid are described. A lubricating device is also provided to equally feed oil to each of portions to be lubricated in the engine, including the main gallery connected to a discharge port of an oil pump via the oil filter. A lidding cover is adhered to the mold. The phase-change material is in direct contact with each IC chip of the at least one IC chip to absorb and dissipate heat generated by the at least one IC chip. The delayed clock signal and the other clock signal are provided as the first and second output clock signals. A plasma doping process is performed to at least a portion of the substrate that is adjacent to the gate structure.