The present invention provides a Sn\u2014Zn based lead-free solder which can prevent peeling of solder from soldered portions even after the passage of long periods after soldering of portions to be soldered made of Cu. In one embodiment, the pressurizing and pressure regulating valve includes a sleeve, a first flow passage formed through the sleeve, a second flow passage formed through the sleeve, and a piston slidably disposed in the sleeve. A plurality of wall panels may be adapted to form a wall panel system. Radioactive material is within at least a portion of the inner channel or coating at least a portion of the outer periphery of each hollow bio-absorbable segment. The lid also includes a projection extending from a portion of the side wall.