Gradient F-doping hydroxyapatite core-shell nanorods (HAP@FAP) (IMAGE) Industrial Chemistry & Materials Caption HAP@FAP piezocatalysts with built-in lattice strain gradient structure was fabricated, showing high catalytic activity for degradation of PHE in soil. Credit Jianmei Lu and Najun Li, Soochow University, China. Usage Restrictions News organizations may use or redistribute this image, with proper attribution, as part of news coverage of this paper only. License Original 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.