Corrosion sealing of amalgam restorations in vitro.

Amalgam restorations, when first placed, have been shown to exhibit a gap at the amalgam/tooth interface. With time in service, this gap fills with corrosion products that have the potential to "seal" the restoration. With the advent of high-copper, more corrosion-resistant amalgams, there has been concern that the time required to create this seal would be increased significantly when compared with low-copper traditional amalgams.

E center in silicon has a donor level in the band gap.

It has been an accepted fact for more than 40 years that the E center in Si (the group-V impurity--vacancy pair)--one of the most studied defects in semiconductors--has only one energy level in the band gap: namely, the acceptor level at about 0.45 eV below the conduction band. We now demonstrate that it has a second level, situated in the lower half of the band gap at 0.

Degradation of boron-doped Czochralski-grown silicon solar cells.

The formation mechanism and properties of the boron-oxygen center responsible for the degradation of Czochralski-grown Si(B) solar cells during operation is investigated using density functional calculations. We find that boron traps an oxygen dimer to form a bistable defect with a donor level in the upper half of the band gap. The activation energy for its dissociation is found to be 1.

Initial mercury evaporation from experimental Ag-Sn-Cu amalgams containing Pd.

This study examined the Hg evaporation during setting from experimental Ag-Sn-Cu alloy powders with and without Pd. Four series of alloy powders were fabricated to examine the effect on the Hg evaporation of the alloy compositions (all percentages in this report are weight percents): Pd (0-1.5), Cu (9.

Influence of liquid films on mercury vapor loss from dental amalgam.

Objectives: The aim of this study was to determine the effect of aqueous liquid films on Hg emission from of dental amalgam.

Methods: Amalgam specimens (4 mm dia. x 4 mm long) made from ten alloys were uniformly abraded on wet ASTM 600 grit SiC paper, quickly dried and covered by liquid films of a thickness that approximated the thickness of saliva films on tooth surfaces in vivo.