The formation and maintenance of the definitive endoderm lineage in the mouse: Involvement of HNF3/f

It is disclosed that when power generating thermopiles comprised of lead telluride thermoelements are operated at temperatures above about 400 DEG C, the metal electrodes in contact with the ends of the thermoelements tend to diffuse into the lead telluride. The metals used for the electrodes are n-type dopants and degrade the properties of the p-type thermoelements. Manganese telluride has a low solid solubility limit in lead telluride. By saturating the p-type lead telluride with manganese telluride, the diffusion of the electrode material into the lead telluride is substantially eliminated without materially reducing the electrical properties.