Diagram illustrating the description of Solvent-Accessible Surface (SAS) for macromolecules, as defined by Fred Richards.  Prepared in Mage and Photoshop.
<a href="//commons.wikimedia.org/wiki/User:DavetheMage" title="User:DavetheMage">DavetheMage</a>
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<span class="int-own-work" lang="en">Own work</span>