Zhong-jin Ruan

Zhong-Jin Ruan, 69, Professor Emeritus of Mathematics at the University of Illinois Urbana-Champaign, passed away peacefully on September 20, 2025, at Carle Hospital. He was born on December 22, 1955, in Tianjin, China.

He earned his B.A. in Mathematics from Nankai University in 1982 and completed his Ph.D. at UCLA in 1987 under Professor Edward G. Effros. His doctoral research produced a landmark result in operator spaces, recognized with the Alfred P. Sloan Doctoral Dissertation Fellowship.

In 1988, he joined the University of Illinois at Urbana-Champaign, where he spent more than 30 years teaching, mentoring, and conducting research. He published extensively, co-authored the influential book Operator Spaces, and received the Mahlon M. Day Award for Distinguished Mathematical Research. He also served as editor for leading mathematics journals and organized international conferences.

He held visiting positions at UC Berkeley, the Fields Institute, the Institute Henri Poincaré, and Zhejiang University.

Zhong-Jin was a devoted husband and father who loved traveling with his family and enjoyed martial arts novels and films.

He is survived by his wife, Lian Jin Ruan; sons, Gordon J. and George J. Ruan; sisters, Enge, Enqian, and Joan Ruan; and granddaughters, Chloe Jade and Arya Grace Ruan.

A memorial service will be held at Sunset Funeral Home and Cremation Center’s Champaign Chapel on Friday, October 24, 2025 at 10:00 a.m., followed by private burial at Mt. Hope Cemetery. In lieu of flowers, donations may be made to the Zhong-Jin Ruan Memorial Scholarship in Mathematics Fund at the University of Illinois Foundation.

Please join his family in sharing memories, photos and videos on his tribute wall at www.sunsetfuneralhome.com.