AUTHOR=Pohrt Roman , Popov Valentin L. TITLE=Editorial: Friction and Wear: From Elementary Mechanisms to Macroscopic Behavior JOURNAL=Frontiers in Mechanical Engineering VOLUME=5 YEAR=2019 URL=https://www.frontiersin.org/journals/mechanical-engineering/articles/10.3389/fmech.2019.00047 DOI=10.3389/fmech.2019.00047 ISSN=2297-3079