1. Postdoctoral Research Associate, Dept. of Materials Science and Engineering, Univ. of Illinois at Urbana-Champaign, Materials Science and Engineering Building, 1304 West Green St., Urbana, IL 61801.
2. Ivan Racheff Professor of Civil and Environmental Engineering, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, 3230 Newmark Civil Engineering Laboratory, 205 N. Mathews Ave., Urbana, IL 61801 (corresponding author).
3. Environmental Engineer, U.S. Environmental Protection Agency, ORD, NRMRL, WSWRD, TTEB, 26 W. Martin Luther King Dr., Cincinnati, OH 45268.
4. Professor, Dept. of Materials Science and Engineering, Univ. of Illinois at Urbana-Champaign, Materials Science and Engineering Building, 1304 West Green St., Urbana, IL 61801.