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designing of covalent organic framework/2D g-C 3 N 4 heterostructure using a simple method for enhanced photocatalytic hydrogen production

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Journal of Colloid and Interface science 2024年 653卷 1650-1661页

作者： Ahmed E. Hassan Ahmed M. Elewa Mai S.A. Hussien Ahmed F.M. EL-Mahdy Islam M.A. Mekhemer Ibrahim S. Yahia Tarek A. Mohamed Ho-Hsiu Chou Zhenhai Wen CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of Nanomaterials Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 China University of Chinese Academy of Sciences Beijing 100049 China Department of Chemistry Faculty of Science Al-Azhar University Nasr City 11884 Cairo Egypt Department of Chemical Engineering National Tsing Hua University Hsinchu 300044 Taiwan Nuclear Chemistry Department Hot Laboratories Center Atomic Energy Authority Cairo 13759 Egypt Nanoscience Laboratory for Environmental and Biomedical Applications (NLEBA) Semiconductor Lab Department of Physics Faculty of Education Ain Shams University Roxy Cairo 11757 Egypt Department of Chemistry Faculty of Education Ain Shams University Roxy Cairo 11757 Egypt Department of Materials and Optoelectronic Science National Sun Yat-Sen University Kaohsiung 80424 Taiwan Laboratory of Nano-Smart Materials for Science and Technology (LNSMST) Department of Physics Faculty of Science King Khalid University P.O. Box 9004 Abha Saudi Arabia Research Center for Advanced Materials Science (RCAMS) King Khalid University Abha 61413 P.O. Box 9004 Saudi Arabia Center of Medical and Bio-Allied Health Sciences Research (CMBHSR) Ajman University Ajman P.O. Box 346 United Arab Emirates

designing heterostructure photocatalysts is a promising approach for developing highly efficient photocatalysts for hydrogen energy production. In this work, we synthesized a series of a covalent organic framework (COF)/g-C 3 N 4 (CN) heterojunction photocatalysts, denoted as x % COF/CN (in which x indicates the weight % of COF and x = 5, 10, 20, 30, 40, 50, 90, 95, 100), for hydrogen production . The COF, which is a key component of the photocatalyst, was prepared by assembling benzothiadiazole (BT) and pyrene (Py) derivatives as building blocks. Integrating COF rods into the two-dimensional (2D) layered g-C 3 N 4 structure significantly improved photocatalytic H 2 production. The hybrid system (30 % COF/CN) displayed an outstanding hydrogen evolution rate (HER) of 27540 ± 805 μmol g −1 h −1 , outperforming most known COFs and g-C 3 N 4 -based photocatalysts, besides exhibiting stable photocatalytic performance. Moreover, the apparent quantum yield (AQY) was 15.5 ± 0.8 % at 420 nm. Experimental techniques and density functional theory (DFT) calculations demonstrated that the 30 % COF/CN heterostructure has broad visible-light absorption, adequate band energy levels, and the best chemical reactivity descriptors compared to the individual components, resulting in effective carrier separation and excellent performance. Our findings offer a valuable strategy for developing highly efficient and stable heterojunction photocatalysts for visible-light‐driven H 2 evolution.

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Tension Characteristics Analysis of Scraper Chain of Heavy-Duty Scraper Conveyor with Time-Varying Loads

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Shock and Vibration 2024年第1期2024卷

作者： Shuai Li Zhencai Zhu Hao Lu Yujun Xue School of Mechatronics Engineering Henan University of Science and Technology Luoyang 471003 China *** Henan Key Laboratory for Machinery Design and Transmission System Luoyang 471003 China Collaborative Innovation Center of Henan Province for High-End Bearing Henan University of Science and Technology Luoyang 471000 China *** Longmen Laboratory Luoyang 471000 China School of Mechatronics Engineering Jiangsu Key Laboratory of Mine Mechanical and Electrical Equipment China University of Mining and Technology Xuzhou 221116 Jiangsu China ***

With the intensification and large scale of coal mining, scraper conveyors are developing towards high power, large volume, long haul distance, and high reliability. It is more and more important to obtain the dynamic tension of the scraper chain with time-varying loads. The purpose of this paper is to obtain the dynamic tension of scraper chains of the scraper conveyor with time-varying loads. First, according to the structural characteristics and working environment of the scraper conveyor and the polygon effect of the sprocket, the scraper conveyor dynamic model under the action of the time-varying loads is established by the finite unit method. Second, the load variation rule of the bearing section is explored when the scraper conveyor and shearer work together. Furthermore, the element resistance of each discrete element, the stiffness coefficient of the scraper chain, and the influence of polygonal effect of sprocket wheel are analyzed. And then, the dynamic tension of the scraper chain is obtained by the Hilber–Hughes–Taylor (HHT) method. Finally, the validity of the scraper conveyor dynamic model is verified by the example analysis and field measurement experiment. Due to the influence of heavy starting, the maximum tension of the scraper chain during the starting process is 751.6 kN, which is 12.25% higher than the tension with smooth running (669.6 kN). During the startup stage, significant impacts occur on both motors and scraper chains which may lead to damage. To protect these components effectively, control strategies such as “soft start” or no-load start hold crucial engineering significance in achieving reliable operation of the scraper conveyor. The obtained results can provide a theoretical basis for the reliability evaluation and parameter optimization of the scraper conveyor.

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Visible‐Light‐Promoted Nickel‐ and Organic‐Dye‐Cocatalyzed Formylation Reaction of Aryl Halides and Triflates and Vinyl Bromides with Diethoxyacetic Acid as a Formyl Equivalent

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Angewandte Chemie 2017年第6期129卷

作者： He Huang Xiangmin Li Chenguang Yu Yueteng Zhang Patrick S. Mariano Wei Wang Department of Chemistry and Chemical Biology University of New Mexico Albuquerque NM 87131 USA State Key Laboratory of Bioengineering Reactor and Shanghai Key Laboratory of New Drug Design School of Pharmacy East China University of Science & Technology 130 Mei-Long Road Shanghai 200237 P.R. China

A simple formylation reaction of aryl halides, aryl triflates, and vinyl bromides under synergistic nickel‐ and organic‐dye‐mediated photoredox catalysis is reported. Distinct from widely used palladium‐catalyzed formylation processes, this reaction proceeds by a two‐step mechanistic sequence involving initial in situ generation of the diethoxymethyl radical from diethoxyacetic acid by a 4CzIPN‐mediated photoredox reaction. The formyl‐radical equivalent then undergoes nickel‐catalyzed substitution reactions with aryl halides and triflates and vinyl bromides to form the corresponding aldehyde products. Significantly, besides aryl bromides, less reactive aryl chlorides and triflates and vinyl halides serve as effective substrates for this process. Since the mild conditions involved in this reaction tolerate a plethora of functional groups, the process can be applied to the efficient preparation of diverse aromatic aldehydes.

关键词： Durchflusschemie Formylierungen Nickelkatalyse Photoredoxkatalyse Synthesemethoden

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Non-Equilibrium Solidification Complexions in Additive Manufacturing Enable Exceptional Creep Resistance: An Example in Nickel-Based Superalloys

SSRN

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SSRN 2024年

作者： Li, Yansong Cui, Luqing Xu, Jinghao Xin, Tongzheng Jiang, Shuang Li, Yao Zhang, Honghong Dang, Xiaofeng Liang, Xiaoqing Gao, Shuang Mu, Yahang Lu, Kaiju Moverare, Johan J. He, Weifeng Shaanxi Xi’an710049 China School of Mechanical Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Division of Engineering Materials Department of Management and Engineering Linköping University LinköpingSE-58183 Sweden School of Materials Science and Engineering Dalian University of Technology Dalian116024 China Key Laboratory of Electromagnetic Processing of Materials Ministry of Education Northeastern University Shenyang110819 China School of Materials Science and Engineering Chang’an University Shaanxi Xi’an710064 China School of Mechanical Engineering Xi’an Shiyou University Shaanxi Xi’an710065 China National Key Lab of Aerospace Power System and Plasma Technology Air Force Engineering University Shaanxi Xi’an710038 China School of Material Engineering Shanghai University of Engineering Science Shanghai201620 China Shenyang110016 China Defense Innovation Institute Academy of Military Science Beijing100071 China

Insufficient time-dependent properties at elevated temperatures, particularly creep resistance and ductility, are currently crucial factors impeding the use of additively manufactured Hastelloy X (HX). To address this limitation, a micro-nano olive-shaped carbide network was purposely introduced into HX via laser powder bed fusion (L-PBF) and following optimized heat treatment. The inherent chemical heterogeneity combined with the sufficient stored energy of boundaries, induced by the ultrafast cooling rate of the L-PBF process, creates favorable conditions for the formation of micro-nano precipitation networks. Compared to its untreated counterpart, the optimized HX exhibited considerably improved creep resistance, with an 83% increase in creep life and a 122% improvement in fracture ductility. Furthermore, through multiscale characterization techniques and theoretical calculations, the preferential precipitation behavior of the micro-nano carbide networks was systematically investigated from both kinetic and thermodynamic perspectives. The superior creep resistance of the L-PBF HX, decorated with carbide networks, stems from the synergistic effects of the higher cavity surface energy, greater pinning force for grain boundary sliding, and lower plasticity-assisted diffusion rate, which markedly inhibit the nucleation and growth of microvoids during high-temperature deformations. This work provides a comprehensive understanding of the strengthening mechanisms associated with non-equilibrium solidification-facilitated carbide networks, providing new insights into the targeted design and optimization of L-PBF alloys. © 2024, The Authors. All rights reserved.

关键词： Creep resistance

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Synthesis of Aldehydes by Organocatalytic Formylation Reactions of Boronic Acids with Glyoxylic Acid

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Angewandte Chemie 2017年第28期129卷

作者： He Huang Chenguang Yu Xiangmin Li Yongqiang Zhang Yueteng Zhang Xiaobei Chen Patrick S. Mariano Hexin Xie Wei Wang Department of Chemistry & Chemical Biology University of New Mexico Albuquerque NM 87131 USA State Key Laboratory of Bioengineering Reactor and Shanghai Key Laboratory of New Drug Design School of Pharmacy East China University of Science & Technology 130 Mei-Long Road Shanghai 200237 P.R. China

Reported herein is a conceptually novel organocatalytic strategy for the formylation of boronic acids. New reactivity is engineered into the α‐amino‐acid‐forming Petasis reaction occurring between aryl boronic acids, amines, and glyoxylic acids to prepare aldehydes. The operational simplicity of the process and its ability to generate structurally diverse and valued aryl, heteroaryl, and α,β‐unsaturated aldehydes containing a wide array of functional groups, demonstrates the practical utility of the new synthetic strategy.

关键词： Arene Bor Formylierungen Organokatalyse Synthesemethoden

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Characteristic Analysis of Monobit Signal

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Journal of Physics: Conference Series 2021年第1期1738卷

作者： Pengfei Ji Xiao Yang Chenglong Xia Huan Lv State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System Technology National University of Defense Technology Changsha Hunan 410073 China. School of Electronic Science National University of Defense Technology Changsha Hunan 410073 China. Military Representative Office of Rocket Force in Changsha Changsha Hunan 4100205 China.

This paper analyzes the characters of monobit signals and gives the reason why the spurious free dynamic ranges (SFDR) of monobit signals is much lower than those of multi-bit signals. According to our analysis and simulation, if the third harmonic of a monobit signal can be filtered, the SFDR of it can be improved well. Therefore, we give the way to obtain the desired band, which do not contain any third harmonics, and the simulation results are in agreement with our design. Such way can be used to improve the performance of monobit digital receivers in engineering.

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Eddy current pulsed thermography for fatigue evaluation of gear

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AIP Conference Proceedings 2014年第1期1581卷 1652-1662页

作者： Gui Yun Tian Aijun Yin Bin Gao Jishan Zhang Brian Shaw School of Automation Engineering University of Electronic Science and Technology of China Chengdu Sichuan 611731 P. R. China and School of Electrical and Electronic Engineering Newcastle University Newcastle upon Tyne NE1 7RU United Kingdom State Key Laboratory of Mechanical Transmission College of Mechanical Engineering Chongqing University P. R. China and School of Electrical and Electronic Engineering Newcastle University Newcastle upon Tyne NE1 7RU United Kingdom Design Unit School of Mechanical Engineering and System Newcastle University Newcastle upon Tyne NE1 7RU United Kingdom

The pulsed eddy current (PEC) technique generates responses over a wide range of frequencies, containing more spectral coverage than traditional eddy current inspection. Eddy current pulsed thermography (ECPT), a newly developed non-destructive testing (NDT) technique, has advantages such as rapid inspection of a large area within a short time, high spatial resolution, high sensitivity and stand-off measurement distance. This paper investigates ECPT for the evaluation of gear fatigue tests. The paper proposes a statistical method based on single channel blind source separation to extract details of gear fatigue. The discussion of transient thermal distribution and patterns of fatigue contact surfaces as well as the non-contact surfaces have been reported. In addition, the measurement for gears with different cycles of fatigue tests by ECPTand the comparison results between ECPT with magnetic Barkhausen noise (MBN) have been evaluated. The comparison shows the competitive capability of ECPT in fatigue evaluation.

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Soft Robots: Fast‐Response, Stiffness‐Tunable Soft Actuator by Hybrid Multimaterial 3D Printing (Adv. Funct. Mater. 15/2019)

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Advanced Functional Materials 2019年第15期29卷

作者： Yuan‐Fang Zhang Ningbin Zhang Hardik Hingorani Ningyuan Ding Dong Wang Chao Yuan Biao Zhang Guoying Gu Qi Ge Digital Manufacturing and Design Centre Singapore University of Technology and Design Singapore 487372 Singapore Soft Robotics and Biodesign Lab Robotics Institute School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai 200240 China Science and Math Cluster Singapore University of Technology and Design Singapore 487372 Singapore

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C³DA: A Universal Domain Adaptation Method for Scene Classification From Remote Sensing Imagery

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IEEE Geoscience and Remote Sensing Letters 2024年 21卷

作者： Jiaxu Guo Yushan Lai Jinxiao Zhang Juepeng Zheng Haohuan Fu Lin Gan Liang Hu Gaochao Xu Xilong Che College of Computer Science and Technology Jilin University Changchun China National Supercomputing Center in Wuxi Wuxi China School of Artificial Intelligence Sun Yat-sen University Zhuhai China Department of Earth System Science Tsinghua University Beijing China Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen China Ministry of Education Key Laboratory for Earth System Modeling and Department of Earth System Science Tsinghua University Beijing China Department of Computer Science and Technology Tsinghua University Beijing China

Various remote sensing applications have widely used domain adaptation (DA) methods. Since it does not need to add human interpretation in the target domain, it can be used in cross-region, multitemporal, and multisensor application scenarios. In order to further optimize the design of the loss function and better address the challenges of DA in remote sensing, in this letter, we propose a new universal DA method named C3DA for scene recognition of remote sensing images. It has a comprehensive C3 criterion for recognizing the “unknown” classes by innovatively fusing confidence, consistency, and certainty of samples to make our network training more efficient. We evaluate the performance of our proposed method based on six transfer tasks on three remote sensing datasets. The evaluation results show that our proposed method achieves an average H-score of 58.44%, significantly higher than other SOTA universal DA methods with an average improvement of 2.32%~29.43%. Compared to the baseline ResNet-50, it achieves up to 19.92% improvement, demonstrating that the proposed method outperforms the universal DA scenario. In the future, we also plan to expand the application of this method to more scenarios.

关键词： Remote sensing Entropy Training Feature extraction Deep learning Adversarial machine learning Vectors

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Finite Element Analysis on Loosen Teeth using Fibrous Periodontal Splint Restoration

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IOP Conference Series: Materials science and Engineering 2018年第1期417卷

作者： Chengshui Ding Xue Shi Yang Song Lulu Qiu Xinyue Li Chunqiu Zhang Tianjin Key Laboratory of the Design Intelligent Control of the Advanced Mechatronical System National Demonstration Center for Experimental Mechanical and Electrical Engineering Education School of Mechanical Engineering Tianjin University of Technology Tianjin 300384 China Periodontitis Department Tianjin Stomatological Hospital Tianjin 300384 China

Objective To investigate the effect of fibre periodontal splint restoration on mandibular anterior teeth displacement and periodontal membrane stress. Methods Micro-CT scanning technology, combined with Mimics, Geomagic studio and SolidWorks were used to establish 3D dental models of mandibles with teeth and the models fibre periodontal splint restoration; the models of mandibular anterior loosen teeth was constructed under 30 degree oblique 25N loading on the labial and lingual sides respectively. Then, under different angles force with or without the splint, the analysis on dental mechanical state are given. Results It was determined that the sum of the maximal displacement of the loosen tooth model at the lingual and labial sides was 1 mm, which represented the degree I loosen model. After splint repair on the model, the maximal displacement of loosen tooth decreased 47.7%, 85.1% and 85.8% at 0 degree, 15 degree and 30 degree forces respectively, and the maximum stress of periodontal membrane decreased by 22.3%, 61.2% and 74.9%. Conclusion Fixation of loosen teeth through fibre periodontal splints can reduce the maximum stress of periodontal membrane and the maximal displacement of the teeth, thus ensuring the stability of loosen tooth.

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