ON THE COVER
Mesoscale materials, phenomena, and functionality. The mesoscale domain, where atomic granularity, quantization of energy, and simplicity of structure and function give way to continuous matter and energy, complex structures, and composite functionalities, represents a new scientific frontier. The articles in this issue of MRS Bulletin explore some of the hallmarks of mesoscale science and highlight current and new research directions. On the cover is a mesoscale-structured lightweight honeycomb architecture created by 3D printing of a fiber-reinforced epoxy ink, where the structures at different length scales can be controlled. Credit: Lori K. Sanders, Brett G. Compton, and Jennifer A. Lewis, Harvard University. See the technical theme that begins on page 919.