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777 results on '"Liu, Wen-bo"'

156. Array piezoelectric plate harvester excited by pneumatic compressed air

Author

刘文博 Liu Wen-bo, 赵希禄 Zhao Xi-lu, 程廷海 Cheng Ting-hai, 赵宏伟 Zhao Hong-wei, and 高海波 Gao Hai-bo

Subjects
Materials science, Acoustics, Excited state, Compressed air, Pneumatic cylinder, Piezoelectricity, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials
Published
2017
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159. The Design Of Passive RFID Smart Bracelet

Author

Wu Hao, Chen xue-liang, Liu wen-bo, and Deng Jian-zhi

Subjects
Microcontroller, Inkwell, business.industry, Computer science, Electrical engineering, STM32, Wireless, Voltage source, Antenna (radio), business, Chip, Energy (signal processing)
Abstract

This paper presents the design of smart bracelet composed of RFID chip M24LR04E-R and STM8L152C6T6 ultra-low power microcontroller, electronic ink screen and PCB antenna. Design prototype have achieved that when the PC-side host computer to send commands, the STM32 microcontroller and CR95HF RF chip reader composed can have short-range wireless communication with the bracelet (distance ≤ 5cm). The wristband electronic ink screen can display the received Information. The highlight of the design is that the M24LR04E-R chip can not only be used as an RFID passive tag, but also has the ability to collect energy and conduct energy output from the electromagnetic field during communication. When it has the wireless communications, the M24LR04E-R can be a voltage source to supply the power to the bracelet. This progress can achieve the passive design of the bracelet. The electronic ink screen used has the characteristic that the display content does not disappear after power-off, and the information displayed on the wristband can be kept for a long time.

Published
2018
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172. Ligand-enabled Ir-catalyzed intermolecular diastereoselective and enantioselective allylic alkylation of 3-substituted indoles† †Electronic supplementary information (ESI) available. CCDC 1060973. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5sc01772f Click here for additional data file. Click here for additional data file

Author

Zhang, Xiao, Liu, Wen-Bo, Tu, Hang-Fei, and You, Shu-Li

Subjects
Chemistry
Abstract

A ligand-enabled Ir-catalyzed diastereoselective and enantioselective allylic alkylation of 3-substituted indoles is reported, providing indoline products containing three contiguous stereocenters in one step with high site-, regio-, diastereo- and enantioselectivities from a wide range of readily available starting materials., An Ir-catalyzed asymmetric allylic alkylation of 3-substituted indoles is reported. The reaction provides indoline products containing multiple contiguous stereocenters with high site-, regio-, diastereo- and enantioselectivities in one step from a wide range of readily available starting materials. The key to this method is the high level of diastereocontrol enabled by an iridium catalyst derived from a N-aryl phosphoramidite ligand (Me-THQphos, 1c).

Published
2015

173. Iron‐Catalyzed Intramolecular C—H Amidation of N‐Benzoyloxyureas.

Author

Zhong, Dayou, Wu, Lin‐Yang, Wang, Xing‐Zhen, and Liu, Wen‐Bo

Subjects
AMIDATION, INTRAMOLECULAR catalysis, BIPYRIDINE, OXIDIZING agents, IRON
Abstract

Main observation and conclusion: A redox‐neutral Fe‐catalyzed intramolecular C—H amidation of N‐benzoyloxyureas is described. This methodology employs a simple iron complex in situ generated from Fe(OTf)2 and bipyridine as the catalyst and N‐benzoyloxyureas as the nitrene precursors without using exogenous oxidants. An array of cyclic ureas were synthesized via aliphatic C(sp3)—H amidation in excellent yields. In addition, this catalytic system is also amenable to aryl C(sp2)—H nitrene insertion to provide benzimidazolones in moderate yields. [ABSTRACT FROM AUTHOR]

Published
2021
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174. Alkali metal hydroxide–catalyzed C(sp)–H bond silylation

Author

Toutov, Anton A., Betz, Kerry N., Schuman, David P., Liu, Wen-Bo, Fedorov, Alexey, Stoltz, Brian M., and Grubbs, Robert H.

Abstract

Disclosed is a mild, scalable, and chemoselective catalytic cross-dehydrogenative C–H bond functionalization protocol for the construction of C(sp)–Si bonds in a single step. The scope of the alkyne and hydrosilane partners is substantial, providing an entry point into various organosilane building blocks and additionally enabling the discovery of a number of novel synthetic strategies. Remarkably, the optimal catalysts are NaOH and KOH.

Published
2017

177. Iron‐Catalyzed Primary C—H Amination of Sulfamate Esters and Its Application in Synthesis of Azetidines†.

Author

Zhang, Yan, Zhong, Dayou, Usman, Muhammad, Xue, Peng, and Liu, Wen‐Bo

Subjects
AMINATION, ESTERS, IRON catalysts
Abstract

Summary of main observation and conclusion: The direct amination of unactivated primary C—H bonds is extremely challenging due to their inert nature. Herein, we report an intramolecular primary C—H amination of sulfamate esters using an iron catalyst derived from iron(II) triflate and bipyridine. An array of oxathiazinanes were synthesized in moderate to good yields, which were further converted into biologically important azetidines by a one‐pot procedure. This research demonstrates the potential of applying simple nitrogen ligands in iron‐catalyzed C—H functionalization and offers an accessible alternative to state‐of‐the‐art iron‐nitrene chemistry. [ABSTRACT FROM AUTHOR]

Published
2020
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178. Recent Advances and Perspectives in the Synthesis and Applications of Tetrahydrocarbazol‐4‐ones†.

Author

Usman, Muhammad, Hu, Xu‐Dong, and Liu, Wen‐Bo

Subjects
OXIDATIVE coupling, INDOLE alkaloids, NATURAL products, ASYMMETRIC synthesis, CATALYSIS
Abstract

Tetrahydrocarbazol‐4‐one represents a prevalent framework of numerous natural products and pharmaceuticals. This review summaries the recent synthetic progresses of this core structure, including Fischer indolization, oxidative and reductive coupling, α‐arylative cyclization by means of transition‐ metal catalysis or under metal‐free conditions, and other methods. The recently emerged enantioselective catalytic methods of tetrahydrocarbazol‐4‐ ones are also described. The mechanistic insights and applications of these strategies as a key step in the total (formal) synthesis of complex alkaloids are highlighted as well. [ABSTRACT FROM AUTHOR]

Published
2020
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188. A new method for image retrieval based on analyzing fractal coding characters

Author

Liu Wen-bo, Huang Xiaoqing, and Zhang Qin

Subjects
business.industry, Computer Science::Information Retrieval, Fractal transform, Kernel density estimation, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, Pattern recognition, Fractal analysis, Fractal, Image texture, Fractal compression, Computer Science::Computer Vision and Pattern Recognition, Histogram, Signal Processing, Media Technology, Computer vision, Computer Vision and Pattern Recognition, Artificial intelligence, Electrical and Electronic Engineering, business, Image retrieval, ComputingMethodologies_COMPUTERGRAPHICS, Mathematics
Abstract

It has been effectively proved that histogram of image fractal coding parameters can be used for image retrieval. In recent years, many researchers have paid more and more attention to this application of image fractal coding. In this paper, a new statistical method, based on kernel density estimation, is used for analyzing fractal coding parameters. The fractal signatures are then extracted for texture image retrieval. Experimental results show that the proposed method not only has higher retrieval rate but also faster retrieval speed than existing method.

Published
2013
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189. HRRP target recognition based on kernel joint discriminant analysis

Author

Yuan Jiawen, Shen Qian, Liu Wen-bo, and Zhang Gong

Subjects
0209 industrial biotechnology, business.industry, Computer science, Feature vector, Feature extraction, Pattern recognition, Small sample, 02 engineering and technology, Linear discriminant analysis, Support vector machine, ComputingMethodologies_PATTERNRECOGNITION, 020901 industrial engineering & automation, Kernel (image processing), Discriminative model, Artificial intelligence, business, Curse of dimensionality
Abstract

With the improvement of radar resolution, the dimension of the high resolution range profile (HRRP) has increased. In order to solve the small sample problem caused by the increase of HRRP dimension, an algorithm based on kernel joint discriminant analysis (KJDA) is proposed. Compared with the traditional feature extraction methods, KJDA possesses stronger discriminative ability in the kernel feature space. K-nearest neighbor (KNN) and kernel support vector machine (KSVM) are applied as feature classifiers to verify the classification effect. Experimental results on the measured aircraft datasets show that KJDA can reduce the dimensionality, and improve target recognition performance.

Published
2019
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195. Ionic and Neutral Mechanisms for C–H Bond Silylation of Aromatic Heterocycles Catalyzed by Potassium tert-Butoxide

Author

Banerjee, Shibdas, primary, Yang, Yun-Fang, additional, Jenkins, Ian D., additional, Liang, Yong, additional, Toutov, Anton A., additional, Liu, Wen-Bo, additional, Schuman, David P., additional, Grubbs, Robert H., additional, Stoltz, Brian M., additional, Krenske, Elizabeth H., additional, Houk, Kendall N., additional, and Zare, Richard N., additional

Published
2017
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196. Potassium tert-Butoxide-Catalyzed Dehydrogenative C–H Silylation of Heteroaromatics: A Combined Experimental and Computational Mechanistic Study

Author

Liu, Wen-Bo, primary, Schuman, David P., additional, Yang, Yun-Fang, additional, Toutov, Anton A., additional, Liang, Yong, additional, Klare, Hendrik F. T., additional, Nesnas, Nasri, additional, Oestreich, Martin, additional, Blackmond, Donna G., additional, Virgil, Scott C., additional, Banerjee, Shibdas, additional, Zare, Richard N., additional, Grubbs, Robert H., additional, Houk, K. N., additional, and Stoltz, Brian M., additional

Published
2017
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200. Effect of F, V and Mn co-doping on the catalytic performance of TiO2-pillared bentonite in the photocatalytic denitration

Author

WANG, Shu-qin, LI, Jin-meng, and LIU, Wen-bo

Abstract

F, V and Mn co-doped TiO2-pillared bentonite was prepared by the sol-gel method and characterized by XRD, nitrogen sorption, UV-vis spectroscopy, SEM, etc.; its performance in the photocatalytic denitration of NO was investigated under visible light irradiation at room temperature. The results indicate that the photocatalytic denitration efficiency of F-V-Mn co-doped TiO2-pillared bentonite for NO at a concentration of 661 μg/m3is approximately 100%; when the concentration of NO increases to 1657 μg/m3, the photocatalytic efficiency decreases to 81.9%, which is however 33.8% higher than that over the unpillared F-V-Mn co-doped TiO2. The reaction rate constant over the F-V-Mn co-doped TiO2-pillared bentonite is twice as high as that over the V-Mn co-doped TiO2pillared bentonite; moreover, the F-V-Mn co-doped TiO2-pillared bentonite also displays improved resistance against water and SO2poisoning. TiO2pillars can not only retain the flaky crystal structure of bentonite, but also increase the distance between bentonite layers from 0.667 to 0.710 nm and enhance the adsorption capacity. Meanwhile, the doping elements can inhibit the growth of TiO2rutile and reduce the band gap of TiO2, which is effective in improving the response to visible light, prolonging the service life, and broadening the application range of TiO2for the photocatalytic denitration.

Published
2020
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