Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
(a,b) The photographs of “HUST” and “USC” patterns lightened by an as-assembled lithium-ion battery (the initials of Huazhong University of Science and Technology & University of Southern California). (c,d) Optical images of three red LEDs driven by a full battery like a Close/Open switch.
