Metal trade development

Industrial hygiene began life in the metals trade. Mining and smelting of metals were the backbone of technological and industrial growth. Indeed, whole eras of human development are associated with the increasing sophistication with which humankind has worked with metals the copper age was succeeded by the bronze age that was in turn succeeded by the iron age. We are embarked on a new age characterized by new materials that define our civilization it may eventually be known as the silicon age. 

Gold [7440-57-5] Au, is presumably the first metal known and used by humans. It occurs ia nature as a highly pure metal and is treasured because of its color, its extraordinary ductility, and its resistance to corrosion. Early uses ia medicine and dentistry date to the ancient Chinese and Egyptians. In the Middle Ages the demand for gold led to the iatense, unsuccesshil efforts of alchemists to convert base metals iato gold. These pursuits became the basis for chemical science. The search for gold has been an important factor ia world exploration and the development of world trade. 

PDC bits get their name from the polycrystalline diamond compacts used for their cutting structure. The technology that led to the production of STRATAPAX drill blanks grew from the General Electric Co. work with polycrystalline manufactured diamond materials for abrasives and metal working tools. General Electric Co. researched and developed the STRATAPAX (trade... 

It has now gained acceptance as an impressed current anode for cathodic protection and has been in use for this purpose since 1971. The anode consists of a thin film of valve and precious metal oxides baked onto a titanium substrate and when first developed was given the proprietary name dimensionally stable anode , sometimes shortened to DSA. Developments on the composition of the oxide film have taken place since Beer s patent, and this type of anode is now marketed under a number of different trade names. 

Zirconia membranes on carbon supports were originally developed by Union Carbide. Ultrafiltration membranes are commercially available now under trade names like Ucarsep and Carbosep. Their outstanding quality is their high chemical resistance which allows steam sterilization and cleaning procedures in the pH range 0-14 at temperatures up to 80°C. These systems consist of a sintered carbon tube with an ultrafiltration layer of a metallic oxide, usually zirconia. Typical tube dimensions are 10 mm (outer diameter) with a wall thickness of 2 mm (Gerster and Veyre 1985). 

For a long time, conventional alkaline electrolyzers used Ni as an anode. This metal is relatively inexpensive and a satisfactory electrocatalyst for O2 evolution. With the advent of DSA (a Trade Name for dimensionally stable anodes) in the chlor-alkali industry [41, 42[, it became clear that thermal oxides deposited on Ni were much better electrocatalysts than Ni itself with reduction in overpotential and increased stability. This led to the development of activated anodes. In general, Ni is a support for alkaline solutions and Ti for acidic solutions. The latter, however, poses problems of passivation at the Ti/overlayer interface that can reduce the stability of these anodes [43[. On the other hand, in acid electrolysis, the catalyst is directly pressed against the membrane, which eliminates the problem of support passivation. In addition to improving stability and activity, the way in which dry oxides are prepared (particularly thermal decomposition) develops especially large surface areas that contribute to the optimization of their performance. 

There has been a variety of approaches for imparting antimicrobial activity to cellulosic fibers, many of them developed as part of a weather-resistant finish (Table I). Metal salts, organometallics, resins, sulfur and nitrogen compounds, and chemical modification of hydroxyl groups by acetylation or cyanoethylation are typical methods used to impart antimicrobial activity (125). A survey made in 1966 lists all commercial products available for protecting materials against biodeterioration— trade names, active ingredients, end uses, and names of manufacturers are tabulated (126). 

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