Dear Javad Hashemifar, Torsten Andersen, and Fred Nastos... I appreciated such clear answers so much. Thank you very much Best regards, Jinbo Yang, Ph.D. Graduate Center for Materials Research University of Missouri-Rolla Rolla, MO 65409-1170 Phone: (573)341-6165 Fax: (573)341-2071 E-mail: jinbo at umr.edu