Atomic and Electronic Structures of Unreconstructed Polar MgO(111) Thin Film on Ag(111)

Atomic and electronic structures of a polar surface of MgO formed on Ag(111) was investigated by using reflection high energy electron diffraction (RHEED), Auger electron spectroscopy, electron energy loss spectroscopy (EELS), and ultraviolet photoemission spectroscopy (UPS). A rather flat unreconstructed polar MgO(111) 1$\times$1 surface could be grown by alternate adsorption of Mg and O$_{2}$ on Ag(111). The stability of the MgO(111) surface was discussed in terms of interaction between Ag and Mg atoms at the interface, and charge state of the surface atoms. EELS of this surface did not show a band gap region, and finite density of states appeared at the Fermi level in UPS. These results suggest that a polar MgO(111) surface was not an insulating surface but a semiconducting or metallic surface.Comment: 6 figures, to be published in Phys. Rev.

Summary of Total Mercury Concentrations in Fillets of Selected Sport Fishes Collected during 2000–2003 from Lake Natoma, Sacramento County, California

This report summarizes results of total mercury measurements in skinless fillets of sport fishes collected during August 2000, September–October 2002, and July 2003 from Lake Natoma, a small (8,760 acre-feet) afterbay for Folsom Dam on the lower American River. The primary objective of the study was to determine if mercury concentrations in fillets approached or exceeded guidelines for human consumption. The Food and Drug Administration (FDA) human-health action level for methylmercury in commercially caught fish is 1.0 μg/g (microgram per gram); the U.S. Environmental Protection Agency (USEPA) human-health criterion for methylmercury residue in fish tissue is 0.30 μg/g. Wet weight concentrations of total mercury in skinless fillets were as high as 0.19 μg/g in bluegill (Lepomis macrochirus), 0.39 μg/g in redear sunfish (L. microlophus), 1.02 μg/g in largemouth bass (Micropterus salmoides), and 1.89 μg/g in channel catfish (Ictalurus punctatus). Maximum concentrations of mercury in other fish species varied from 0.10 μg/g in rainbow trout (Oncorhynchus mykiss) to 0.56 μg/g in white catfish (Ameiurus catus). Altogether, 1 of 86 largemouth bass and 11 of 11 channel catfish exceeded the FDA human-health action level. In addition, 1 of 20 redear sunfish, 26 of 86 largemouth bass, 2 of 3 spotted bass (M. punctulatus), 1 of 1 brown bullhead (A. nebulosus), and 1 of 1 white catfish exceeded the USEPA human-health criterion. These results indicate that some fish species inhabiting Lake Natoma contain undesirably high concentrations of mercury in their skinless fillets

Assessment of Technologies for Reducing CO2 Emission

There are a wide variety of technologies for reducing CO2 emissions, of which a greater part are those of energy technologies. The paper aims at assessing these technologies with regional differences of technology characteristics taken into account. The first part examines merits and demerits of individual technology, and thus envisages its possible future. The second part describes a global energy model, which generates comprehensive long term future scenarios of energy and CO2 emission in various regions of the world

Summary of Total Mercury Concentrations in Fillets of Selected Sport Fishes Collected during 2000–2003 from Lake Natoma, Sacramento County, California

This report summarizes results of total mercury measurements in skinless fillets of sport fishes collected during August 2000, September–October 2002, and July 2003 from Lake Natoma, a small (8,760 acre-feet) afterbay for Folsom Dam on the lower American River. The primary objective of the study was to determine if mercury concentrations in fillets approached or exceeded guidelines for human consumption. The Food and Drug Administration (FDA) human-health action level for methylmercury in commercially caught fish is 1.0 μg/g (microgram per gram); the U.S. Environmental Protection Agency (USEPA) human-health criterion for methylmercury residue in fish tissue is 0.30 μg/g. Wet weight concentrations of total mercury in skinless fillets were as high as 0.19 μg/g in bluegill (Lepomis macrochirus), 0.39 μg/g in redear sunfish (L. microlophus), 1.02 μg/g in largemouth bass (Micropterus salmoides), and 1.89 μg/g in channel catfish (Ictalurus punctatus). Maximum concentrations of mercury in other fish species varied from 0.10 μg/g in rainbow trout (Oncorhynchus mykiss) to 0.56 μg/g in white catfish (Ameiurus catus). Altogether, 1 of 86 largemouth bass and 11 of 11 channel catfish exceeded the FDA human-health action level. In addition, 1 of 20 redear sunfish, 26 of 86 largemouth bass, 2 of 3 spotted bass (M. punctulatus), 1 of 1 brown bullhead (A. nebulosus), and 1 of 1 white catfish exceeded the USEPA human-health criterion. These results indicate that some fish species inhabiting Lake Natoma contain undesirably high concentrations of mercury in their skinless fillets