A strained Si layer 2 is epitaxially grown on a base SiGe layer 1, and a gate insulating film 3a and a gate electrode 4a are formed. The method of the present invention is capable of welding a Si-based material, which is difficult to weld by conventional methods due to its brittle nature and high electric resistance. The polymer composition is used to provide improved corrosion and ultraviolet radiation resistance when used with naturally corrosive or pressure preservative treated wood. The acting valve is connected to the connecting mechanism.