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Rapid synthesis of highly active Pt/C catalysts with various metal loadings from single batch platinum colloid

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Journal of Energy Chemistry 2020年第8期29卷 138-145,I0005页

作者： Yuxin Li Xiang Zhu yawen chen Shiqiao Zhang Jia Li Jianguo Liu Jiangsu Key Laboratory for Nano Technology National Laboratory of Solid State MicrostructuresCollege of Engineering and Applied Sciencesand Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093JiangsuChina Kunshan Innovation Institute of Nanjing University Kunshan Sunlaite New Energy Co.Ltd.Suzhou 215347JiangsuChina

A series of Pt/C catalysts for proton exchange membrane fuel cells(PEMFCs) with various metal loadings is synthesized by a microwave-assisted polyol process via mixing an extremely stable platinum colloid(> 3 months’ shelf life) from single batch preparation with activated carbon ethylene glycol suspension.21 wt%, 42 wt% and 61 wt% Pt loadings are employed to showcase the advantages of the improved polyol process. The ultraviolet(UV)–visible spectra and ζ-potential measurements are conducted to monitor the wet chemistry process during catalyst preparation. The powder X-ray diffraction(XRD), transmission electron microscopy(TEM) and thermogravimetric analysis(TGA) characterizations are carried out on catalysts. The catalyst activities are investigated using electrochemical and single cell tests. The stability of Pt nanoparticle colloid is explored by ORR, cyclic voltammetry(CV) and ζ-potential measurements. The TEM results show the Pt particle sizes of the colloid, and the sizes of the 21 wt%, 42 wt% and 61 wt%Pt/C samples are 2.1–3.9 nm. Because of the high Pt dispersion, the Pt/C catalysts exhibit superior electroactivity toward ORR. In addition, four 61 wt% Pt/C catalysts made from the Pt colloid with 0–3 months’ shelf life show almost the same performance, which exhibits superior stability of the Pt colloid system without surfactant protection.

关键词： PEMFC Pt/C catalyst Microwave irradiation Modified polyol process Platinum nanocolloid Oxygen reduction reaction

Reduced frame set on wireless distorted video for quality assessment

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The Journal of China Universities of Posts and Telecommunications 2016年第4期23卷 77-82,100页

作者： Shao Hua Wen Xiangming Lu Zhaoming chen yawen Lu Jingyu Beijing Laboratory of Advanced Information Networks Beijing University of Posts and Telecommunications Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications

Objective video quality assessment methods often evaluate all the frames regardless of their importance. For wireless distorted videos, not every frame has the same contribution to the final overall quality due to the channel fading and interference, which may lead to the capacity variation in temporal. Besides, with the content similarity and error propagation pattern in temporal domain, it is possible to evaluate the overall quality with only part of the frames. In this paper, a demonstration is performed to show that the video quality can be evaluated with reduced frames set（RFS）, and a state transition model is proposed to extract the RFS. At last, a video quality assessment（VQA） method is carried out based on RFS. Compared with several state-of-the-art methods, our method can achieve a suitable accuracy with less frames to be processed.

关键词： VQA wireless distortion quality of experience

Joint hybrid beamforming and power splitting design in millimeter-wave simultaneous wireless information and power transfer system

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The Journal of China Universities of Posts and Telecommunications 2019年第2期26卷 59-66页

作者： Bao Tiantian Wen Xiangming Lu Zhaoming chen yawen Zheng Wei School of Information and Communication Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China Beijing Laboratory of Advanced Information Networks Beijing University of Posts and TelecommunicationsBeijing 100876China Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and TelecommunicationsBeijing 100876China

A joint hybrid beamforming and power splitting(JHBPS) design problem for simultaneous wireless information and power transfer(SWIPT) in millimeter-wave(mmWave) system is *** considered scenario is a multi-antenna base station(BS) transfers information and energy simultaneously to multiple single-antenna *** adopts hybrid digital and analog beamforming architecture to reduce hardware *** separate acquired signals with power splitters either for information decoding(ID) or energy harvesting(EH).The aim is minimizing total transmission power by joint design of hybrid beamforming and PS under ID and EH *** is difficult to obtain the optimal hybrid beamformer directly since the analog beamformer and digital beamformer are ***,a two-stage algorithm is proposed to solve the *** the first stage,the optimal beamformer and PS ratios are obtained by solving the joint transmission beamforming and PS design *** the second stage,the optimal beamformer is approximated with the product of analog beamformer and digital *** superiority of proposed algorithm over the existing algorithms is demonstrated through ***,the effectiveness of approximation algorithm is testified.

关键词： SWIPT mmWave hybrid analog and digital beamforming

HYDROGEN ABSORPTION OF FeTi+x wt-% La ALLOYS WITH ALTERNATE LAYER STRUCTURE

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Acta Metallurgica Sinica(English Letters) 1992年第5期5卷 354-357页

作者： QIAN Jiuxin ZHANG yawen chen Xudong Peking University,Beijing,China Peking Univ Beijing China

Superior hydrogen absorbability of the alloys fo FeTi-La with alternate layer structure was found *** would be available at 30℃ under 6 MPaH_2 without any prior treatment.

关键词： FeTi La hydrogen absorption

Inspecting design rules of metal-nitrogen-carbon catalysts for electrochemical CO_(2)reduction reaction:From a data science perspective

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Nano Research 2023年第1期16卷 264-280页

作者： Rui Ding Meng Ma yawen chen Xuebin Wang Jia Li Guoxiong Wang Jianguo Liu National Laboratory of Solid State Microstructures College of Engineering and Applied SciencesNanjing University22 Hankou RoadNanjing 210093China State Key Laboratory of Catalysis Dalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China

The development of inexpensive metal-nitrogen-carbon(M-N-C)catalysts for electrochemical CO_(2)reduction reaction(CO_(2)RR)on an industrial scale has come to a *** the number of related studies and reviews has grown fast,the complexity of the M-N-C composite has limited researchers to focus on only a few variables and carry out sluggish trial-and-error optimizations in their *** a result,the conclusions are drawn only by artificial analysis based on a few orthogonal experimental *** obtain more general design strategies,we have innovatively introduced machine learning(ML)into this field to address this bottleneck.A standard workflow that comprehensively utilizes different ML algorithms and black-box interpretation methods is proposed for this *** predicting CO_(2)RR performance metrics for M-N-C catalysts,such as maximum faradaic efficiency with great accuracy,the ML models have also indicated simple and clear design strategies that would guide future exploration from a data science ***,we have also demonstrated the potential of the models in guiding the development of new material *** thereby believe that the new research paradigm proposed may accelerate the development of this field soon.

关键词： electrochemical CO_(2)reduction reaction metal-nitrogen-carbon catalyst machine learning artificial intelligence data science

Molecular mechanism of the inhibitory effect of methylation outside the recognition sequence of restriction endonuclease Pvu Π on its cleavage activity

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Chinese Science Bulletin 1998年第1期43卷 47-52页

作者： chen Defeng, SUN Mei, LIU Yingmiao, SHI Guoli and chen yawen Institute of Molecular Biology, Nankai University, Tianjin 300071, China Institute of Molecular Biology Nankai University Tianjin China

In 1991, we found that methylation outside the PvuⅡ recognition sequence could partially inhibit its cleavage activity. To clarify the molecular mechanism, three plasmids with different methylation states were constructed. Then, together with the original one, four plasmids were digested with different amounts of PvuⅡ. Results show that methylation on both sites results in 90% inhibition; moving the methylated site one base further away decreases the inhibitory effect to about 30%; with the adjacent dam methylation site eliminated, the inhibitory effect disappears. The data suggest that the inhibition of cleavage activity caused by outside methylation is not "all or none", and the degree of inhibition is dependent on the position and the number of methylated bases.

关键词： methylation outside the recognition sequence molecular mechanism PCR sitespecific mutation restriction endonuclease PvuⅡ.

Vertebrate Dynein-f depends on Wdr78 for axonemal localization and is essential for ciliary beat

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Journal of Molecular Cell Biology 2019年第5期11卷 383-394页

作者： Yirong Zhang yawen chen Jianqun Zheng Juan Wang Shichao Duan Wei Zhang Xiumin Yan Xueliang Zhu State Key Laboratory of Cell Biology CAS Center for Excellence in Molecular Cell Science Shanghai Institute of Biochemistry and Cell Biology University of Chinese Academy of Sciences Chinese Academy of Sciences 320 Yueyang Road Shanghai 200031 China

Motile cilia and flagella are microtubule-based organelles important for cell locomotion and extracellular liquid flow through beating. Although axonenal dyneins that drive ciliary beat have been extensively studied in unicellular Chlamydomonas, to what extent such knowledge can be applied to vertebrate is poorly known. In Chlamydomonas, Dynein-f controls flagellar waveforms but is dispensable for beating. The flagellar assembly of its heavy chains (HCs) requires its intermediate chain (IC) IC140 but not IC138. Here we show that, unlike its Chlamydomonas counte『part, vertebrate Dynein-f is essential for ciliary beat. We confirmed that Wdr78 is the vertebrate orthologue of IC3 Wdr78 associated with Dynein-f subunits such as Dnah2 (a HC) and Wdr63 (IC140 orthologue). It was expressed as a motile cilium-specific protein in mammalian cells. Depletion of Wdr78 or Dnah2 by RNAi paralyzed mouse ependymal cilia. Zebrafish Wdr78 morphants displayed ciliopathy-related phenotypes, such as curved bodies, hydrocephalus, abnormal otolith, randomized left-right asymmetry, and pronephric cysts, accompanied with paralyzed pronephric cilia. Furthermore, all the HCs and ICs of Dynein-f failed to localize in the Wdr78-depleted mouse ependymal cilia. Therefore, both the functions and subunit dependency of Dynein-fare altered in evolution, probably to comply with ciliary roles in higher organisms.

关键词： axonemal dynein Dynein-f IC138 motile cilium primary ciliary dyskinesia Wdr78 Dnah2

Enhanced light harvesting ability in hollow Pt/TiO2 nanoreactor for boosting tetracycline photodegradation

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Progress in Natural Science:Materials International 2024年第4期34卷 767-775页

作者： Danyang Li Yongqi Li Dagui Liao Mengqing Cao Lulu Zhang Shasha Zhang Ling chen yawen chen Huan Wang Jian Qi Feifei You College of Textile and Clothing Yancheng Institute of Technology Hebei Key Laboratory of Flexible Functionals Materials School of Materials Science and Engineering Hebei University of Science and Technology State Key Laboratory of Biochemical Engineering Institute of Process Engineering Chinese Academy of Sciences School of Chemical Engineering University of Chinese Academy of Sciences

Utilizing solar energy to decompose tetracycline（TC） is a green strategy to treat wastewater. Herein, a heterogeneous hollow structured TiO2decorated Pt nanoparticles were successfully designed and synthesized via hardtemplate approach and photo-deposition process toward TC photodegradation. The Pt nanoparticles loaded on the surface of hollow structured TiO2can increase the visible light absorption due to the local surface plasmon resonance（LSPR） effect. Furthermore, owing to the tough electron oscillation of the LSPR excitation, the plasmonic hot holes on the surface of Pt nanoparticles can capture the electrons of TiO2, effectively facilitating the separation of photo-excited charge carriers because of the formation of Schottky junction constructed between Pt and TiO2. Combined the natural merits of shorten conveying path of charge carriers and physical structural stability for hollow structure, the optimal Pt/TiO2hetero-junction hybrid showed superior photocatalytic activity and durability for TC photodegradation with the degradation efficiency of 93.8 % after 30 min and the rate constant of 0.09196 min-1under 300 W Xe lamp irradiation. This work displays a heterogeneous hybrids catalyst based on eco-friendly metal and semiconductor materials which can be used in the fields including without limitation TC photodegradation.

关键词： Hollow structure Photodegradation Tetracycline Hetero-junction

Study on optimal state estimation strategy with dual distributed controllers based on Kalman filtering

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High Technology Letters 2019年第1期25卷 105-110页

作者： chen yawen Wang Zhuwei Fang Chao Xu Guangshu Zhang Yanhua School of Information and Communications Engineering Beijing University of Technology

Considering dual distributed controllers, a design of optimal state estimation strategy is studied for the wireless sensor and actuator network(WSAN). In particular, the optimal linear quadratic(LQ) control strategy with estimated plant state is formulated as a non-cooperative game with network-induced delays. Then, using the Kalman filter approach, an optimal estimation of the plant state is obtained based on the information fusion of the distributed controllers. Finally, an optimal state estimation strategy is derived as a linear function of the current estimated plant state and the last control strategy of multiple controllers. The effectiveness of the proposed closed-loop control strategy is verified by the simulation experiments.

关键词： optimal state estimation strategy wireless sensor and actuator network(WSAN) distributed controllers Kalman filter network-induced delays