Reduction indirect contamination

The revolatilization of condensable vapors will decreases vacuum potential by replenishing the vapors in the system you were just trying to remove. This can create an artificially high maximum limit on the pump s potential vacuum. In addition to the backstreaming of vapors, the pump itself is affected when condensable vapors contaminate the pump s oil. Not only will this decrease the vapor pressure of the pump oil, but the condensed vapors can cause a reduction of lubrication and sealing properties of the oil and lead to an eventual corrosion of the pump s internal parts.16 Other condensed liquids (such as hydrocarbons) can mix, emulsify, and/or break down the pump oil. They can also directly destroy a pump by chemical attack, or indirectly, by poor pump performance, they can cause extra wear and tear on the pump parts. 

Chapter 2 considers the removal of inorganic water contaminants using photocatalysis. Metal cations react via one-electron steps first leading to unstable chemical intermediates, and later to stable species. Three possible mechanisms are identified (a) direct reduction via photo-generated conduction band electrons, (b) indirect reduction by intermediates generated from electron donors, and (c) oxidative removal by electron holes or hydroxyl radicals. The provided examples show the significance of these mechanisms for the removal of water contaminants such as chromium, mercury, lead, uranium, and arsenic. 

Most retinoid reductions have been reported in response to organic contaminants, but other pollutants may affect storage levels. Lake trout (Salvelinus namaycush) inhabiting an area contaminated with iron-ore mine tailings had hepatic retinol and retinyl palmitate levels reduced by approximately 95%80. These fish also exhibited oxidative damage, providing indirect evidence that the loss of retinoid stores may be related to increased oxidative stress. 

A number of batch and column studies have sought to enhance the solubilization and desorption of PAHs from soil. Surfactants are commonly used to remediate PAH-contaminated soil. Two methods are employed micellar solubilization and PAH mobilization by reduction of interfacial tension (West and Harwell, 1992). As surfactant toxicity became a significant issue, biodegradable and biocompatible surfactants have been more widely examined. For example, food-grade surfactants such as Tergitol 15-S-X (X = 7,9, and 12) (Li and Chen, 2002) and other surfactants with indirect food additive status, such as alkyl diphenyl disulfonate (DOWFAX) (Deshpande et /., 2000), have been investigated for use in solubilization/desorption of single PAHs or PAHs mixtures from contaminated soils. 

Until recently the evidence involving NADPH cytochrome c reductase (a ilavoprotein) in the cytochrome P-450 catalysed reactions was indirect The concept was first based on the fact that cytochrome c blocked drug metabolism, presumably by diverting electrons from NADPH cytochrome c reductase in micro-somes to cytochrome oxidase in the mitochondria which invariably contaminate microsomal preparations. The view was more firmly established by the finding that on treatment of liver microsomes with various concentrations of steapsin, retention of the NADPH cytochrome c reductase in microsomes paralleled the retention of cytochrome P-450 reductase and aniline hydroxylase. The best evidence implicating the flavoprotein was recently obtained by Omura, who showed that a specific antibody for NADPH cytochrome c reductase inhibited both cytochrome P-450 reduction and drug metabolism by liver microsomes. 

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