Invited for this month's Cover are the groups at Tsinghua University, Max‐Planck Institute of Colloids and Interfaces, and Penn State University, and their collaborators at Harbin Institute of Technology and Stanford University. They present a new nitrogen‐doped ionothermal carbon aerogel (NDC) air cathode for use in microbial fuel cells, allowing high power generation and simultaneous wastewater treatment. The Full Paper itself is available at 10.1002/cssc.201600590.

Inertial piezoelectric actuators work by matching the impact driving force and friction. Most inertial piezoelectric actuators generate an impact force difference between the forward and backward motion, while the friction keeps unchanged. This paper proposed an inertial actuator driven by the friction difference in a cycle. Friction was actively regulated with an electromagnet to match the symmetric driving force. A prototype with symmetrical cantilever structure and electromagnet friction adjusting unit was fabricated. The dynamic model of the actuator is established and a series of experiments were conducted to verify the feasibility of the driving principle. Experiment results indicated that the actuator based on active friction regulation worked stably and exhibited excellent bearing capacity. Active friction regulation, with the help of magnetic force, could be a promising alternative to the dominant working principle of inertial actuator.

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