1. Dept. of Food; Bioprocessing and Nutrition Sciences; North Carolina State Univ.; Box 7624; Raleigh; NC 27695; U.S.A.
2. Laboratory for Advanced Electron and Light Optical Methods; Population Health and Pathobiology Dept.; North Carolina State Univ.; 1060 William Moore Drive; Raleigh; NC 27607; U.S.A.