MAIK W. JORNITZ is Director of Product Management at Sartonus Headquarters, Gottingen, Germany. With over 10 years of experience in separation technologies, Mr. Jornitz supports the biopharmaceutical industry worldwide in validation, integrity testing, and air and water filtration. A member of the Parenteral Drug Association and the International Society of Pharmaceutical Engineers, among others, he is the author, coauthor, or coeditor of numerous professional papers on membrane filters, integrity testing, and validation studies, including Filtration in the Biopharmaceurical Industry (Marcel Dekker, Inc.). Mr. Jornitz received the Diploma in Engineering from the Technical University of Hamburg, Germany. THEODORE H. MELTZER, based in Bethesda, Maryland, is a consultant on filtration and high- purity water preparation to the pharmaceutical and semiconductor industries. With over 40 years of experience in membrane separations, Dr. Meltzer holds four patents, and is the author, coauthor, or coeditor of Filtration in the Pharmaceutical Industry, Filtration in the Biopharmaceutical Industry (both titles, Marcel Dekker, Inc.), High Purity Water Preparation for the Semiconductor, Pharmaceutical and Power Industries, and Phar,naceutical Water Systems as well as many professional papers and book chapters that reflect his research interests in the structure—property relationships in membrane filters, filter systems, and their validation. A member of the American Chemical Society, the Parenteral Drug Association, and the Filtration Society, Dr. Meltzer received the Ph.D. degree in physical- organic chemistry from the University of Chicago, Illinois. He pursued postdoctoral work in polymer mechanical properties at Princeton University, Princeton, New Jersey.