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129 results on '"Mao, Yiwei"'

7. A human-specific enhancer fine-tunes radial glia potency and corticogenesis

Author

Liu, Jing, primary, Mosti, Federica, additional, Zhao, Hanzhi T., additional, Sotelo-Fonseca, Jesus E., additional, Escobar-Tomlienovich, Carla F., additional, Lollis, Davoneshia, additional, Musso, Camila M., additional, Mao, Yiwei, additional, Massri, Abdull J., additional, Doll, Hannah M., additional, Sousa, Andre M., additional, Wray, Gregory A., additional, Schmidt, Ewoud, additional, and Silver, Debra L., additional

Published
2024
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28. Binder jetting additive manufacturing of 316L stainless-steel green parts with high strength and low binder content: Binder preparation and process optimization

Author

Wei Li, Qingsong Wei, Mao Yiwei, Daosheng Cai, and Li Jingwen

Subjects
0209 industrial biotechnology, Materials science, Metals and Alloys, 02 engineering and technology, Surface finish, Layer thickness, Industrial and Manufacturing Engineering, Computer Science Applications, 020303 mechanical engineering & transports, 020901 industrial engineering & automation, Compressive strength, 0203 mechanical engineering, Flexural strength, Modeling and Simulation, Ceramics and Composites, Surface roughness, Metal powder, Process optimization, Composite material, Saturation (chemistry)
Abstract

Recently, binder jetting additive manufacturing (BJAM) was used to manufacture complex metal parts in an economical and large-scale way. However, the usage of resin to bond metal powder renders as-printed green parts with low strength, which is potential to cause the structural damages of final parts during post treatments. To overcome the intractable problem, a self-developed binder mainly consisting of A-stage phenolic resin was explored for BJAM to achieve relatively high-strength as-printed green parts. The binder can be cured as a C-stage phenolic resin with 190 ℃ and then provide a high strength for the green parts. The effect of layer thickness and binder saturation on the strength, dimensional accuracy, and surface roughness of the BJAM-printed 316 L stainless-steel green samples using the developed binder was investigated systematically. With the optimized parameters (a layer thickness of 100 μm and a binder saturation of 30.2 %), green samples can possess the ultimate bending strength (UBS) of 10.08 MPa and the ultimate compressive strength (UCS) of 25.56 MPa, which are beneficial for the structural stability of the printed samples during subsequent treatments. A reduction in strength and an increase in roughness are observed with increasing the layer thickness for the as-printed green samples. An increment in binder saturation results in the improvement in strength and surface roughness of the green samples. The relationships between the binder and the mechanical performance of the green samples were discussed from the viewpoint of the uneven distribution of binder in depth. This work explored a promising binder with a low saturation for BJAM to fabricate 316 L green parts with desirable mechanical strength and acceptable surface roughness.

Published
2021

46. Growth of SnO2 nanocrystals co-doped with Eu3+ for highly enhanced photoluminescence in mesoporous silica glasses.

Author

Chen, Ping, Mao, Yiwei, Hou, Shaodong, Chen, Yang, Liu, Xiaofen, Lou, Yang, Chen, Aichen, Yang, Luyun, Li, Jinyan, and Dai, Nengli

Abstract

This study reports the growth of SnO2 nanocrystals (NCs) in mesoporous silica glasses and its great enhancement of Eu3+ photoluminescence at around 590 nm wavelength-band. Significantly different energy level character of Eu3+ was observed using photoluminescence (PL) spectra, which was attributed to the effect of the SnO2 crystal field. Remarkably, enhancement of Eu3+ as much as 116 times was achieved in the orange emission region by optimal SnO2 NCs addition. PL excitation spectra and decay curves verify the efficient energy transfer from SnO2 NCs to Eu3+. It is well understood that the highly enhanced emission originates from Eu3+ embedded in SnO2 NCs and the strong energy transfer between them. Our study has not only demonstrated an effective way to enhance down-conversion PL of rare earth ions in silica glasses, but also widened the applications of semiconductor oxides such as SnO2 NCs. [ABSTRACT FROM AUTHOR]

Published
2019
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47. Study on the semi-solid rheocasting of magnesium alloy by mechanical stirring

Author

D. N. Li, Gang Wu, Shusen Wu, Mao Yiwei, Jiancheng Luo, X. J. Song, and Zhongxu Xiao

Subjects
Materials science, Magnesium, Metallurgy, Metals and Alloys, chemistry.chemical_element, equipment and supplies, Microstructure, Casting, Industrial and Manufacturing Engineering, Grain size, Computer Science Applications, Shear rate, Barrel, chemistry, Modeling and Simulation, Ceramics and Composites, Slurry, Magnesium alloy
Abstract

In this work, the effect of the pouring temperature of magnesium melt, the preheating temperature of the barrel of the screw mixer and the shear rate, on the solidified microstructures of semi-solid slurry was investigated by the mechanical stirring method. The appropriate processing parameters of slurry preparation were obtained. The mold filling for a thin-walled casting was examined. The results indicated that the solid volume fraction of non-dendritic structure increased with decrease in the pouring temperature of the magnesium melt and in the barrel preheating temperature of the screw mixer. Also, the grain size of the primary α-phase was reduced. Furthermore, the solid volume fraction of semi-solid non-dendritic structure decreased with increase in the shear rate. At the same time, the grain size of the primary α-phase changed slightly. A fine round granular solidified structure of 30–50 μm of prepared AZ91D magnesium semi-solid slurry was obtained. Finally, it was possible to successfully fabricate a 1.0 mm extremely thin-walled casting with a clear contour and good soundness.

Published
2002

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