Extent of Cation-Exchange Reactions (IMAGE) University of Pennsylvania Caption Using only chemical reactants, engineers transformed semiconducting nanowires into a variety of useful, nanoscale materials. Credit Ritesh Agarwal, the University of Pennsylvania Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.