On July 13th, Prof. Duan Zheng returned to our group to visit the teachers and students. Prof. Duan once studied in Prof. Xi's group before pursuing a Ph.D. at Hokkaido University in Japan. In 2005, he joined Zhengzhou University as a professor. During his visit, Prof. Duan toured our lab, guided by Prof. Zhang. We had friendly discussions and took memorable photos together. It was an unforgettable experience!