| 1 | Challenges and strategies in high-accuracy manufacturing of the world’s largest SiC aspheric mirror显示文摘In the process of manufacturing the world’s largest silicon carbide(SiC)aspheric mirror,the primary difficulties are mirror blank preparation,asphere fabrication,and testing,as well as cladding and coating.Specifically,the challenges include the homogeneity of the complicated structure casting,accuracy and efficiency of the fabrication process,print-through effect,fidelity and precision of test procedure,stress and denseness of cladding process,the dynamic range of interferometric measurement,and air turbulence error due to the long optical path.To break through such a barrier of difficulties,we proposed the water-soluble room temperature vanishing mold and gel casting technology,homogeneous microstructure reaction-formed joint technology,nano-accuracy efficient compound fabrication,gravity unloading technology,high-denseness low-defect physical vapor deposition(PVD)Si-cladding technology,test data fusion method,and time-domain averaging method,etc.Based on the proposed technologies and methods,we have accomplished the world’s largest SiC aspheric mirror with a size of φ4.03 m.The impressive performance of the SiC aspheric mirror is validated by the characteristics of the fabricated SiC aspheric mirror.The aerial density of the SiC blank is less than 120 kg/m^(2),surface shape test accuracy is better than 6 nm RMS,thickness inhomogeneity of the cladding layer is less than 5%,and the final surface figure error and roughness are 15.2 nm RMS and 0.8 nm RMS,respectively. | Xuejun Zhang Haixiang Hu Xiaokun Wang Xiao Luo Ge Zhang Wenxing Zhao Xiaoyi Wang Zhenyu Liu Ling Xiong Erhui Qi Congcong Cui Yanchao Wang Yingjie Li Xu Wang Longxiang Li Yang Bai Qiang Cheng Zhiyu Zhang Ruigang Li Wa Tang Xuefeng Zeng Weijie Deng Feng Zhang | 2022 | Light(Science & Applications)2022，11，12： | 3 |
| 5 | Asymmetric Total Synthesis of Phomarol显示文摘The first and asymmetric total synthesis of phomarol,an uncommon C25 steroid,is described.The synthetically challenging benzocycloheptane motif,found in phomarol and some other naturally occurring molecules,was synthesized efficiently using a very mild acid-promoted type I[5+2]cycloaddition,followed by regio-and chemoselective cleavage of the C-O bond and aromatization cascade.This work is the first example of using the hydrogen bonding between the hydroxy group and oxidopyrylium ylide to control the stereoselectivity of cycloadditions. | Jian-Hong Fan Jing-Jing Wang Fangfang Li Guannan Wang Qiang Guo Lung Wa Chung Chuang-Chuang Li | 2021 | CCS Chemistry2021，3，12： | 0 |
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