title: Mechanical metamaterials: Smaller and stronger.
authors.affiliation: Center for Advanced Mechanics and Materials, Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Li
authors.affiliation: School of Engineering, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Huajian
authors.initials: H
authors.lastname: Gao