On July 5, Science published the latest research achievement "Large Plasticity in Magnesium Mediated by Pyramidal Dislocations" jointly made by Dr. Zhai Xiaobo of School of Science of Xi'an University of Science and Technology and research teams both home and abroad.
FIG. 1 Large plasticity of submicrometer-size magnesium; FIG. 2 The plasticity observed in experiments is mediated by pyramidal dislocation slip;
FIG. 3 The glide of individual pyramidal dislocations captured by in-situ TEM; FIG. 4 Three-dimensional image reconstruction helps to analyze the shape and slip surface of pyramidal dislocations
Magnesium is a promising light material, but the poor plasticity limits its wide application. This study found that poor plasticity is not an intrinsic property of magnesium, and the plasticity of magnesium can be improved effectively by promoting the slip of pyramidal dislocations. The team demonstrated that for submicrometer-scale pure magnesium, various types of pyramidal dislocations (edge, screw, and hybrid) can not only slip, but also lead to very large plasticity. The team speculated that high stress promotes the nucleation and slip of pyramidal dislocations, which in turn enhances the plasticity of the test sample. Through further analysis, not only the slip surface of dislocations is determined, but also important phenomena that have never been reported before are clearly observed, including the cross slip of pyramidal dislocations, the formation of dislocation dipoles and the to-and-fro motion of dislocations. The achievement provides important experimental data for improving the plasticity theory of magnesium and enlightens the development of high plastic magnesium alloys. In this thesis, Dr. Zhai Xiaobo is responsible for the reconstruction of three-dimensional structure of transmission electron microscopy (TEM) data from material tomography.
The paper is completed by 8 units, of which Xi'an Jiaotong University is the highest contribution unit and Xi'an University of Science and Technology is the second highest contribution unit. The paper is signed by 11 authors and Zhai Xiaobo ranks fourth. Dr. Liu Boyu, the young lecturer of Xi'an Jiaotong University, is the first author of this thesis and the Ph.D. Candidate Dr. Liu Fei is the first co-author. Professor Shan Zhiwei of Xi'an Jiaotong University, Professor Nie Jianfeng of Monash University in Australia and Professor Li Bin of University of Nevada in the United States are the co-corresponding authors. Also participating in the work are Professor Zhang Lei of Xi'an Jiaotong University, Ph.D. Candidate Yang Nan, Professor Li Ju of Massachusetts Institute of Technology (MIT), Professor Ma En of The Johns Hopkins University, and Ph.D. Candidate Yang Yang of the University of Nevada. The research is supported by National Key R&D Program of China, National Natural Science Foundation of China, 111 Program 2.0, China Postdoctoral Science Foundation, Shaanxi Key Industry Innovation Chain and other programs.
In addition to the top-notch work published in Science, Zhai also collaborated with other units in June of this year on another important achievement, "Transport of a graphenanoheet sandwiched inside cell membranes," which confirms the sandwich structure of graphene-cell membrane experimentally and demonstrates the kinetic mechanism of the transport of graphene oxide (GOs) sandwiched in the cell membranes, proving the applicability of sandwich GOs in enhancing the membrane-specific drug delivery efficiency. The results of this study provide a favorable support for enhancing the design of inside-membrane delivery of two-dimensional nanomaterials in the field of biomedicine, and were published in Science Advances, the sub-journal of Science. This is the first time that a lecturer of Xi'an University of Science and Technology has published important scientific findings in the main and sub-journals of Science. Science is one of the most influential and authoritative top scientific journals in the world which focuses on the report of major original scientific achievements in the world. The impact factor of Science in 2018 was as high as 41.037.