Layer of synthetic melanin (IMAGE) Northwestern University Caption Illustration of a layer of the synthetic melanin sits on top of inflamed skin. Just under the surface of the skin are green free radicals, also known as ROS, or "reactive oxygen species." Credit Yu Chen, Northwestern University Usage Restrictions Credit accordingly. 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.