1. Forest Products Laboratory, USDA Forest Service, Madison, WI 53705 and Department of Bacteriology, University of Wisconsin, Madison, WI 53706, U.S.A.
2. National Biomedical ESR Center, Medical College of Wisconsin, Milwaukee, WI 53226, U.S.A.
3. Department of Chemistry, SUNY College of Environmental Sciences and Forestry, Syracuse, NY 13210,U.S.A.
4. Department of Biochemistry and Biophysics, Chalmers University of Technology, G6teborg, Sweden