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Single-atom heterogeneous catalysts based on distinct carbon nitride scaffolds

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National Science Review 2018年第5期5卷 642-652页

作者： Zupeng Chen Evgeniya Vorobyeva Sharon Mitchell Edvin Fako Nuúria López Sean M.Collins Rowan K.Leary Paul A.Midgley RolAND Hauert Javier Pérez-Ramírez institute for Chemical and Bioengineering Department of Chemistry and Applied BiosciencesETHZurich institute of Chemical research of Catalonia (ICIQ) The Barcelona Institute of Science and Technology 3. Department of Materials Science and MetallurgyUniversity of Cambridge 4. EmpaSwiss Federal Laboratories for Materials Science and Technology

Carbon nitrides integrating macroheterocycles offer unique potential as hosts for stabilizing metal atoms due to their rich electronic structure. To date, only graphitic heptazine-based polymers have been ***, we demonstrate that palladium atoms can be effectively isolated on other carbon nitride scaffolds including linear melem oligomers and poly(triazine/heptazine imides). Increased metal uptake was linked to the larger cavity size and the presence of chloride ions in the polyimide structures. Changing the host structure leads to significant variation in the average oxidation state of the metal, which can be tuned by exchange of the ionic species as evidenced by X-ray photoelectron spectroscopy and supported by density functional theory. Evaluation in the semi-hydrogenation of 2-methyl-3-butyn-2-ol reveals an inverse correlation between the activity and the degree of oxidation of palladium, with oligomers exhibiting the highest activity. These findings provide new mechanistic insights into the influence of the carbon nitride structure on metal stabilization.

关键词： single-atom heterogeneous catalysts carbon nitride scaffolds alkyne semi-hydrogenation density functional theory metal–host interaction

Formation of β' phase in LPSO structures in an Mg88Co5Y7 alloy

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Journal of Magnesium and Alloys 2022年第1期10卷 175-182页

作者： Q.Q.Jin X.H.Shao Y.T.Zhou B.Zhang S.J.Zheng X.L.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua Road110016 ShenyangChina Materials Science and Engineering research Center Guangxi University of Science and TechnologyLiuzhou 545006China School of Materials Science and Engineering Research Institute for Energy Equipment MaterialsHebei University of TechnologyTianjin 300130China

Formation of β’ phase in long-period stacking ordered(LPSO) structures in an Mg;Co;Y;(at.%) alloy after aging at 200 °C for 24 h or electron beam(EB) irradiation has been studied by high-angle annular dark-field scanning transmission electron microscopy(HAADFSTEM). β’ phase was precipitated only in the Mg matrix but not in LPSO structures after aging at 200 °C for 24 h. LPSO structure containing stacking defects transforms into the β’-long phase during EB irradiation, which plays a key role in accelerating solute atoms’ diffusion. New complex β’(LPSO) structures formed in the alloy after EB irradiation, such as β’(12 H) structure with an orthorhombic lattice(Mg;Y, Cmcm,a = 2 _(a0)= 0.642 nm, b=4√3_(a0), c = 6 _(c0)= 3.12 nm).

关键词： Magnesium alloys Long-period stacking ordered(LPSO)structure HAADF-STEM β’phase

Heterogeneous system synthesis of high quality PbS quantum dots for efficient infrared solar cells

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Nano research 2023年第4期16卷 5750-5755页

作者： Bo Wang Mingyu Li Yuxuan Liu Xinyi Liang Yang Yang Xinzheng Lan Liang Gao Jianbing Zhang Jiang Tang Wuhan National Laboratory for Optoelectronics(WNLO) Huazhong University of Science and Technology(HUST)Wuhan 430074China School of Optical and Electronic Information Huazhong University of Science and Technology(HUST)Wuhan 430074China Wenzhou Advanced Manufacturing technology research institute Huazhong University of Science and TechnologyWenzhou 325035China Shenzhen Huazhong University of Science and technology research institute Shenzhen 518057China Optics Valley Laboratory Wuhan 430074China

As promising optoelectronic materials,lead sulfide quantum dots(PbS QDs)have attracted great ***,their applications are substantially limited by the QD quality and/or complicated ***,a facile new synthesis is developed for highly monodisperse and halide passivated PbS *** new synthesis is based on a heterogeneous system containing a PbCl_(2)-Pb(OA)_(2)solid-liquid precursor *** solid PbCl_(2)inhibits the diffusion of monomers and maintains a high oversaturation condition for the growth of PbS QDs,resulting in high *** addition,the PbCl_(2)gives rise to halide passivation on the PbS QDs,showing excellent stability in *** high monodispersity and good passivation endow these PbS QDs with outstanding optoelectronic properties,demonstrated by a 9.43%power conversion efficiency of PbS QD solar cells with a bandgap of~0.95 eV(1,300 nm).We believe that this heterogeneous strategy opens up a new avenue optimizing for the synthesis and applications of QDs.

关键词： heterogeneous system synthesis lead sulfide quantum dots high monodispersities halide passivation infrared solar cells

Plasma surface treatment of Cu by nanosecond-pulse diffuse discharges in atmospheric air

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Plasma Science and technology 2018年第1期20卷 74-81页

作者：章程邱锦涛孔飞侯兴民方志殷禹邵涛 institute of Electrical Engineering Chinese Academy of Sciences University of Chinese Academy of Sciences School of Automation and Electrical Engineering Nanjing University of Technology China Electric Power research institute

Nanosecond-pulse diffuse discharges could provide high-density plasma and high-energy electrons at atmospheric pressure. In this paper, the surface treatment of Cu by nanosecond-pulse diffuse discharges is conducted in atmospheric air. Factors influencing the water contact angle （WCA）, chemical composition and microhardness, such as the gap spacing and treatment time, are investigated. The results show that after the plasma surface treatment, the WCA considerably decreases from 87~ to 42.3~, and the surface energy increases from 20.46 mJ m-2 to 66.28 mJ m-2. Results of energy dispersive x-ray analysis show that the concentration of carbon decreases, but the concentrations of oxygen and nitrogen increase significantly. Moreover, the microhardness increases by approximately 30% after the plasma treatment. The aforementioned changes on the Cu surface indicate the plasma surface treatment enhances the hydrophilicity and microhardness, and it cleans the carbon and achieves oxidization on the Cu surface. Furthermore, by increasing the gap spacing and treatment time, better treatment effects can be obtained. The micmhardness in the case of a 2.5 cm gap is higher than that in the case of a 3 cm gap. More oxygen and nitrogen species appear on the Cu surface for the 2.5 cm gap treatment than for the 3 cm gap treatment. The WCA significantly decreases with the treatment thne when it is no longer than 90 s, and then it reaches saturation. In addition, more oxygen-containing and nitrogen-containing groups appear after extended plasma treatment time. They contribute to the improvement of the hydrophilicity and oxidation on the Cu surface.

关键词： nanosecond pulse diffuse discharge surface treatment copper water contact angle,microhardness

Precise relative rotation sensing using slow light

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Chinese Physics B 2010年第1期19卷 378-381页

作者：王楠掌蕴东王号田赫邱巍王金芳袁萍 National Key Laboratory of Tunable Laser technology Institute of Opto-electronicsHarbin Institute of Technology

A novel relative rotation sensor based on slow light is proposed and analysed. A theoretical analysis shows that the high sensitivity of the proposed rotation sensor is achieved through an electromagneticaIly-induced-transparency medium. Unlike the tradition detection method, the idea of rotation sensing is to detect group delay between counterpropagating wave packets. It can be used to realize an ultra-precise rotation sensor.

关键词： Sagnac effect relative rotation group delay

Microstructure and impact toughness of 16MND5 reactor pressure vessel steel manufactured by electrical additive manufacturing

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Journal of Iron and Steel research International 2020年第8期27卷 992-1004页

作者： Xi-kou He Chang-sheng Xie Li-jun Xiao Ying Luo Di Lu Zheng-dong Liu Xi-tao Wang institute for Special Steels China Iron and Steel Research InstituteBeijing 100081China Collaborative Innovation Center of Steel technology University of Science and Technology BeijingBeijing 100083China Science and technology on Reactor System Design technology Laboratory Nuclear Power Institute of ChinaChengdu 610041SichuanChina Southern Additive Science and technology Co. Ltd.Foshan 528225GuangdongChina

Electrical additive manufacturing can improve manufacturing efficiency and reduce the cost of 16MND5 reactor pres-sure vessel steel. Impact tests were conducted to compare the impact toughness of 16MND5 steels manufactured by the electrical additive manufacturing and conventional forging, respectively. It is found that the impact toughness of electrical additive manufacturing specimen was slightly higher than that of conventional forging specimen. The characterizations of microstructure show that there were large ferrites and carbides in electrical additive manufacturing specimen. The fracture mechanisms of electrical additive manufacturing specimen were that microvoids or microcracks were prone to nucleate at the large ferrite/bainite interface and large carbide/bainitic ferrite interface, where the stress concentration was high. In addi-tion, the block size and high-angle grain boundaries played a vital role in hindering crack propagation of electrical additive manufacturing specimen, helping to improve the impact energy and leading to a low ductile–brittle transition temperature. The results suggest that the electrical additive manufacturing technology was an effective method to enhance the impact toughness of 16MND5 steel.

关键词： Electrical additive manufacturing 16MND5 steel Impact toughness Fracture High-angle grain boundary

Distributed Resource Allocation in Ultra-Dense Networks via Belief Propagation

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China Communications 2015年第11期12卷 79-91页

作者： CHEN Siyi XING Chengwen FEI Zesong Beijing institute of technology

Ultra-dense networking is widely accepted as a promising enabling technology to realize high power and spectrum efficient communications in future 5G communication systems. Although joint resource allocation schemes promise huge performance improvement at the cost of cooperation among base stations,the large numbers of user equipment and base station make jointly optimizing the available resource very challenging and even prohibitive. How to decompose the resource allocation problem is a critical issue. In this paper,we exploit factor graphs to design a distributed resource allocation algorithm for ultra dense networks,which consists of power allocation,subcarrier allocation and cell association. The proposed factor graph based distributed algorithm can decompose the joint optimization problem of resource allocation into a series of low complexity subproblems with much lower dimensionality,and the original optimization problem can be efficiently solved via solving these subproblems iteratively. In addition,based on the proposed algorithm the amounts of exchanging information overhead between the resulting subprob-lems are also reduced. The proposed distributed algorithm can be understood as solving largely dimensional optimization problem in a soft manner,which is much preferred in practical scenarios. Finally,the performance of the proposed low complexity distributed algorithm is evaluated by several numerical results.

关键词： resource allocation distributed optimization belief propagation(BP) ultradense network

Effects of CeF_3 on properties of self-shielded flux cored wire

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China Welding 2006年第2期15卷 31-33页

作者：喻萍田志凌潘川薛锦 National Engineering research Center for Advance Steel technology Central Iron & Steel Research Institute Xi’an Jiaotong University

Effects of CeF3 on properties of self-shielded flux cored wire including welding process, inclusions in weld metal and mechanical properties are systematically studied. Welding smoke and spatter are reduced with the addition of CeF3. The main non-metallic inclusions in weld metal are AlN and Al2O3. CeF3 can refine non-metallic inclusions and reduce the amount of large size inclusions, which is attributed to the inclusion floating behavior during the solidification of weld metal. The low temperature impact toughness is improved by adding suitable amount of CeF3 in the flux.

关键词： CeF3 self-shielded flux cored wire non-metallic inclusions notch toughness

Multi-scale modeling for prediction of mechanical performance in brazed GH99 thin-walled structure

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Chinese Journal of Aeronautics 2024年第7期37卷 550-563页

作者： Yazhou LIU Shengpeng HU Yanyu SONG Wei FU Xiaoguo SONG Ning GUO Weimin LONG State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China Shandong institute of Shipbuilding technology Weihai 264209China China Machinery Intelligent Equipment Innovation research institute(Ningbo)Co. Ltd.Ningbo 315700China

Superalloy thin-walled structures are achieved mainly by brazing,but the deformation process of brazed joints is non-uniform,making it a challenging research *** paper records a thorough investigation of the effect of brazing parameters on the microstructure of joints and its mechanical properties,which mainly inquires into the deformation and fracture mechanisms in the shearing process of GH99/BNi-5a/GH99 *** macroscopic-microscopic deformation mechanism of the brazing interface during shearing was studied by Crystal Plasticity(CP)and Molecular Dynamics(MD)on the basis of the optimal brazing *** experimental results show that the brazing interface is mainly formed by(Ni,Cr,Co)(s,s)and possesses a shear strength of approximately 546 *** shearing fracture of the brazed joint occurs along the brazing seam,displaying the characteristics of intergranular *** simulations show that dislocations disassociate and transform into fine twinning with increased *** simulated the shear deformation process of the brazed *** multiscale simulation results are consistent with the experimental *** mechanical properties of thin-walled materials for brazing are predicted using MD and CP methods.

关键词： Multi-scale modeling Brazing Shear mechanisms Crystal plasticity GH99 superalloy