The effect of smoking and light activity on metabolism in men.

This experiment examined the metabolic effects of smoking during rest and light activity under naturalistic conditions. Thirty-nine male subjects first completed a submaximal graded exercise treadmill test to standardize activity level. Then 3 groups of subjects—smokers smoking (SS), smokers not smoking (SNS), and nonsmokers (NS)—were exposed to 3 stages of rest or 3 stages of light activity with order of rest or activity randomly determined over 2 different days. Energy expenditure was monitored continuously during these sessions. Significant increases in smokers' energy expenditure were observed during light activity when compared with smokers not smoking and nonsmokers. No differences were identified among groups at rest. These findings strengthen the conclusion that smoking or its components contribute to metabolic changes during typical levels of daily activity and suggest a mechanism for the frequently observed relationship between smoking status and body weight. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pyrroloquinoline quinone acts with flavin reductase to reduce ferryl myoglobin in vitro and protects isolated heart from re-oxygenation injury

Pyrroloquinoline quinone has been isolated from bacteria and recently has been detected in mammalian tissues and fluids. We report in vitro studies which show that pyrroloquinoline quinone serves as a high-affinity substrate for an erythrocyte "flavin reductase" and that the pyrroloquinoline quinol generated by this catalysis reacts rapidly with ferryl myoglobin radical. Western blot analysis of rat and rabbit heart homogenates detects a cross-reactive protein which has a molecular weight identical to the erythrocyte reductase from the same species. Low concentrations of pyrroloquinoline quinone protect isolated rabbit heart from re-oxygenation injury, serving as an effective tissue-protective agent in this model for cellular oxidative damage. We propose that this tissue protection is due to a pyrroloquinoline quinol-mediated reduction of reactive oxygen species.     

Oxygen exchange in oxidation of an Fe-20Cr-10Al alloy in ∼10 mbar O2/H2O-gas mixtures at 920°C

The oxidation of an alumina forming Fe-200-10Al alloy was studied in situ. The gas phase components in isotopically labeled 10 mbar O₂/H₂O-gas mixtures were measured from a virtually closed system at 920°C. Oxidation rates and oxygen-exchange rates were measured and related to each other. From the exchange rates the dissociation rates of O₂ and H₂O were calculated. These dissociation rates were in the early stage of oxidation found to be the same as the oxidation rate. The rate of oxygen exchange with the oxide can exceed the oxidation rate. From this follows that in analysis of a two-stage oxidation in^16,16O₂/^18,18O₂ the exchange rate of O between the oxide and gas phase has to be considered. The oxides formed in H₂O containing gas had a H/O-ratio of 0.1. Vacuum annealing of the alloy before oxidation increased the oxidation rate by a factor of 2.     

Water Corrodes Copper

According to a current concept, copper canisters of thickness 0.05 m will be safe for nuclear waste containment for 100,000 years. We show that more than 1 m copper thickness might be required for 100,000 years durability based on water exposures of copper for 20 h, 7 weeks, 15 years, and 333 years. An observed evolution of hydrogen which involves heterogeneous catalysis of molecular hydrogen, first principles simulations, thermodynamic considerations and corrosion product characterization provide further evidence that water corrodes copper resulting in the formation of a copper hydroxide. These findings cast additional doubt on copper for nuclear waste containment and other important applications.     

Self-Repairing Metal Oxides

The oxidation of Cu, Zr, and alloys forming chromia, alumina, and zirconia was studied in a closed reaction chamber in O₂ gas near 20 mbar. Information on the position of oxide growth has been gained from the ¹⁸O/SIMS technique. Rates of O₂ dissociation on metal oxides, Au, and Pt have been evaluated from measurements in labeled O₂. The experimental results indicate that hydrogen in the metal substrates induces increased metal-ion transport in internal oxide surfaces during oxidation, which leads to increased oxide growth at the oxide–gas interface. Experiments also show that oxides of rare-earth metals (REM) and Pt catalyze the dissociation of O₂. An increased rate of O₂ dissociation can lead to increased transport of oxygen ions in the oxides and increased oxide growth at the substrate–oxide interface. A balanced transport of metal and oxygen ions in metal oxides that leads to oxide growth at both the metal–oxide and at the oxide–gas interface is found to be favorable for the formation of protective oxides with good adherence to the metal substrate. Depending on the original proporation of metal–to–oxygen ion transport in the oxide, an addition of hydrogen will increase or decrease the oxidation kinetics. In analogy, an addition of REM will increase or decrease the oxidation kinetics, depending on the original proportion of metal-to-oxygen ion transport.     

Hydrogen gas production during corrosion of copper by water

This paper considers the corrosion of copper in water by: (1) short term, open system weight measurements and (2) long term, closed system immersion in distilled water (13,800 h) without O₂ at 21–55 °C. In the latter experiments, the hydrogen gas pressure is measured above the immersed copper and approaches ∼10⁻³ bar at equilibrium. This pressure is mostly due to copper corrosion and greatly exceeds that in ambient air. Accordingly, this measured hydrogen pressure from copper corrosion increases with temperature and has the same dependency as the concentration of OH⁻ in the ion product [OH⁻] [H⁺].     

California's Task Force evaluation of issues confronting water reuse.

Water reclamation and reuse have been occurring in California for over a century. The state is arid and semi-arid in large regions and must rely on a variety of water supplies to meet its water demands. Reclaimed water is a potential source to meet a significant portion of new demands expected by 2030. However, there are issues of public health and water quality regulation, cost, public acceptance, institutional and other barriers that must be addressed. The California State Legislature adopted legislation in 2001 to convene the Recycled Water Task Force to advise the state on the opportunities for using reclaimed water in a broad spectrum of applications and in identifying impediments and constraints to increasing the use of reclaimed water. The processes for conducting the Task Force are described to illustrate the actions that were intended to increase the credibility of the Task Force. The recommendations of the Task Force are summarized.     

Platinum-catalyzed high temperature oxidation of metals

Samples of Al, Cr, Ni, and Zr were sputter-coated with porous Pt-films with a particle size of 20-30 nm. Thermal oxidation of these samples was studied by gas phase analysis (GPA) and secondary ion mass spectrometry (SIMS). SIMS analysis on partly Pt-coated samples of Al, Cr, Ni, and Zr at different oxide depths in areas with Pt and in areas away from Pt indicates an enhanced inward oxide growth in the Pt area and mm-ranged distance from Pt-area. Weight gain measurements on Pt-coated Ni samples show a reduced or increased oxidation rate depending on the amount of porous Pt-coating. Pt has two effects on the thermal oxidation of metals and the overall effect of Pt on the oxidation of metals depends on the mechanism of oxide growth in the absence of Pt.     

Selective oxidation of a ferritic stainless steel and its influence on resistance to crevice corrosion initiation

The correspondence between alloy surface composition of a thermally oxidized ferritic stainless steel and resistance to crevice corrosion initiation has been elucidated by means of Auger electron spectroscopy, ion-sputtering and standard electrochemical analyses. When no chromium-alloy depletion is detected, the resistance to crevice corrosion initiation increases with the chromium content of the protective film. When chromium depletion is detected, its detrimental effect on resistance to crevice corrosion initiation increases with the polarizing potential of the sample. Those protective films which possess the highest resistance are shown to have thicknesses < 5 nm.