Red/Green Diagnosis (IMAGE) University of Copenhagen - Faculty of Science Caption These are two light emitting lanthanides working in unison to reveal oxygen levels in living tissue. Credit Microscopy Zhiyu Liao, University of Copenhagen 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.