1. Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California Davis, Davis, California 95616, U.S.A.
2. Department of Earth Sciences, University of Arkansas at Little Rock, Little Rock, Arkansas 72204-1099, U.S.A.
3. Geochemistry and Interfacial Sciences Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6110, U.S.A.