sentences:  Introduced by Zhou Enlai, he went to Yan'an.Later the same year, he participated in the foundation of the Yan’an Institute of Natural Science, directly reported to Mao Zedong on this project, and held the position of the academic dean of the Institute.From 1938 to 1948, he served as a variety of technical development positions assigned by the central government, e.g.,the director of the experimental institute of the Shanxi-Chaha’er-Hebei Military Area.