A wall framework includes top and bottom tracks, a horizontal channel and vertical studs. A remaining side of the U-shaped movable iron piece is inserted in a through-hole section of the coil bobbin and has a resilient characteristic that it is spaced away from the one side. The resultant material provides improved properties over conventional medium density FRC products, in particular improved freezethaw durability andor improved workability. The nanostructure is preferably a quantum dot such as a ZnS capped CdSe core. 5 to 15% B2O3, 5 to 10% Bi2O3, 1 to 10% P2O5, 0 to 5% Sb2O3, 0 to 5% SnO2, 0 to 5% TiO2 and 5 to 10% ZrO2 by mass, wherein is one or several alkali metals and is one or several bivalent metals from the group comprising alkaline earth metals and zinc, and wherein the glaze is obtained by melting or sintering the components.