Abstract: Processes and apparatus are disclosed for producing clear reverse osmosis retentates having silica concentrations which are substantially supersaturated in silica from feedwaters having silica concentrations, without substantial formation of alkali-soluble scale having substantial silica content in the associated reverse osmosis apparatus, by adjusting the pH of such feedwaters to an acidic pH range prior to reverse osmosis in accordance with this invention. Also disclosed are related processes and apparatus for periodically removing minor amounts of alkali-soluble scale having substantial silica content from the apparatus.

Abstract: Processes and apparatus are disclosed for producing clear reverse osmosis retentates having silica concentrations which are substantially supersaturated in silica from feedwaters having silica concentrations, without substantial formation of alkali-soluble scale having substantial silica content in the associated reverse osmosis apparatus, by adjusting the pH of such feedwaters to an acidic pH range prior to reverse osmosis in accordance with this invention. Also disclosed are related processes and apparatus for periodically removing minor amounts of alkali-soluble scale having substantial silica content from the apparatus.

Abstract: The present invention relates to alloys containing about 50-90% palladium, 0-37% gold, 0-3% platinum, 0-35% silver, 0.5-8% gallium, 0-8% tin, and up to 0.2% of a grain refiner selected from the group consisting of iridium, rhenium and ruthenium, or mixtures thereof. In order to withstand the forces of mastication over long spans or cantilever sections, the alloys are more rigid than conventional palladium based alloys. The alloys may be utilized for conventional crown and bridgework or may be fabricated into a number of different prostheses for use on dental implants. These applications include, for example, metal base plates for dentures, metal retaining bars for removable or fixed removable dentures, full metal coverage crowns and bridges, and metal substructures to be veneered with resin or porcelain materials.

Abstract: Dental restorations are made of a high palladium alloy which consists essentially of, on a weight basis, 70-82 percent palladium; 5-8 percent gold; 6.5-8 weight percent silver; 5-9 percent gallium; from 4 to 8 weight percent of a surface oxide producing modifier selected from the group consisting of indium, tin and mixtures thereof, from 0.01 up to 2 percent, ordinarily less than about 0.5 percent, of an oxygen scavenging component which is a member selected from the group consisting of germanium, lithium and mixtures thereof; and up to 2 percent of a grain refiner selected from the group consisting of ruthenium, rhenium and iridium. Alloy can be melted without the need of shielding the alloy from the atmosphere.

Abstract: Dental restorations are made of a palladium alloy which consists essentially of, on a weight basis, 50-85 percent palladium; 5-40 percent of at least one metal selected from the group consisting of copper and cobalt; 1-15 percent gallium; up to 5 percent of a modifier selected from the group consisting of nickel, gold, indium, ruthenium, tin and mixtures thereof; from 0.005 up to 1 percent, ordinarily less than about 0.2 percent, of an oxygen scavenging component which is a member selected from the group consisting of germanium, lithium, and mixtures thereof; and up to 0.5 percent of a grain refiner selected from the group consisting of rhenium and iridium. The alloy is free of boron.