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Singlet Oxygen Induced Site-Specific Etching Boosts Nitrogen-Carbon Sites for High-Efficiency Oxygen Reduction

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Angewandte Chemie 2023年第21期135卷

作者： Guanying Ye Prof. Suqin Liu Kuangmin Zhao Prof. Zhen He College of Chemistry and Chemical Engineering Central South University 410083 Changsha Hunan P. R. China Contribution: Conceptualization (lead) Data curation (lead) Formal analysis (lead) Investigation (lead) Validation (lead) Writing - original draft (lead) Hunan Provincial Key Laboratory of Chemical Power Sources Central South University 410083 Changsha Hunan (P. R. China Contribution: Conceptualization (lead) Funding acquisition (lead) Investigation (lead) Project administration (lead) Writing - review & editing (lead) Contribution: Investigation (supporting) Validation (supporting)

Targeted construction of carbon defects near the N dopants is an intriguing but challenging way to boost the electrocatalytic activity of N-doped carbon toward oxygen reduction reaction (ORR). Here, we report a novel site-specific etching strategy that features targeted anchoring of singlet oxygen ( 1 O 2 ) on the N-adjacent atoms to directionally construct topological carbon defects neighboring the N dopants in N-doped carbon ( 1 O 2 −N/C). This 1 O 2 −N/C exhibits the highest ORR half-wave potential of 0.915 V RHE among all the reported metal-free carbon catalysts. Pyridinic-N bonded with a carbon pentagon of the neighboring topological carbon defects is identified as the primary active configuration, rendering enhanced adsorption of O 2 , optimized adsorption energy of the ORR intermediates, and a significantly decreased total energy barrier for ORR. This 1 O 2 -induced site-specific etching strategy is also applicable to different precursors, showing a tremendous potential for targeted construction of high-efficiency active sites in carbon-based materials.

关键词： Carbon Defect Electrocatalysis N-Doped Carbon ORR Targeted Etching

On self-duality and hulls of cyclic codes over 2m[u]huki with oddly even length

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arXiv 2019年

作者： Cao, Yonglin Cao, Yuan Fu, Fang-Wei School of Mathematics and Statistics Shandong University of Technology Zibo Shandong255091 China Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering Changsha University of Science and Technology Changsha Hunan410114 Hubei Key Laboratory of Applied Mathematics Faculty of Mathematics and Statistics Hubei University Wuhan430062 Chern Institute of Mathematics and Lpmc Tianjin Key Laboratory of Network and Data Security Technology Nankai University Tianjin300071 China

Let F2m be a finite field of 2m elements, and R = F2m[u]/huki = 2m + u2m + . . . + uk-1F2m (uk = 0) where k is an integer satisfying k ≥ 2. For any odd positive integer n, an explicit representation for every self-dual cyclic code over R of length 2n and a mass formula to count the number of these codes are given first. Then a generator matrix is provided for the self-dual and 2-quasi-cyclic code of length 4n over F2m derived by every self-dual cyclic code of length 2n over 2m + u2m and a Gray map from 2m + u2m onto F22 m. Finally, the hull of each cyclic code with length 2n over F2m +uF2m is determined and all distinct self-orthogonal cyclic codes of length 2n over 2m + u2m are listed. Copyright © 2019, The Authors. All rights reserved.

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New Exact Solutions of Kolmogorov Petrovskii Piskunov Equation, Fitzhugh Nagumo Equation, and Newell-Whitehead Equation

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Advances in mathematical Physics 2020年第1期2020卷

作者： Chu, Yu-Ming Javeed, Shumaila Baleanu, Dumitru Riaz, Sidra Rezazadeh, Hadi Department of Mathematics Huzhou University Huzhou 313000 China Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering Changsha University of Science and Technology Changsha 410114 China Department of Mathematics Comsats University Islamabad Park Road Chak Shahzad Islamabad Pakistan Department of Mathematics Cankaya University Ankara Turkey Institute of Space Sciences Magurele-Bucharest Romania Department of Mathematics Riphah International University Sector I-14 Islamabad Pakistan Faculty of Engineering Technology Amol University of Special Modern Technologies Amol Iran

This work presents the new exact solutions of nonlinear partial differential equations (PDEs). The solutions are acquired by using an effectual approach, the first integral method (FIM). The suggested technique is implemented to obtain the solutions of space-time Kolmogorov Petrovskii Piskunov (KPP) equation and its derived equations, namely, Fitzhugh Nagumo (FHN) equation and Newell-Whitehead (NW) equation. The considered models are significant in biology. The KPP equation describes genetic model for spread of dominant gene through population. The FHN equation is imperative in the study of intercellular trigger waves. Similarly, the NW equation is applied for chemical reactions, Faraday instability, and Rayleigh-Benard convection. The proposed technique FIM can be applied to find the exact solutions of PDEs. © 2020 Yu-Ming Chu et al.

关键词： Integrable system Differential equation

Multiple residual dense networks for reconfigurable intelligent surfaces cascaded channel estimation

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arXiv 2021年

作者： Jin, Yu Zhang, Jiayi Huang, Chongwen Yang, Liang Xiao, Huahua Ai, Bo Wang, Zhiqin The School of Electronic and Information Engineering Beijing Jiaotong University Beijing100044 China The Frontiers Science Center for Smart High-speed Railway System Beijing Jiaotong University Beijing100044 China Zhejiang Provincial Key Lab of Information Processing Communication and Networking Zhejiang University Hangzhou310007 China College of Computer Science and Electronic Engineering Hunan University Changsha410082 China ZTE Corporation State Key Laboratory of Mobile Network Mobile Multimedia Technology Shenzhen518057 China State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing100044 China Henan Joint International Research Laboratory of Intelligent Networking and Data Analysis Zhengzhou University Zhengzhou450001 China Research Center of Networks and Communications Peng Cheng Laboratory Shenzhen518055 China China Academy of Information and Communications Technology Beijing100191 China

Reconfigurable intelligent surface (RIS) constitutes an essential and promising paradigm that relies programmable wireless environment and provides capability for space-intensive communications, due to the use of low-cost massive reflecting elements over the entire surfaces of man-made structures. However, accurate channel estimation is a fundamental technical prerequisite to achieve the huge performance gains from RIS. By leveraging the low rank structure of RIS channels, three practical residual neural networks, named convolutional blind denoising network, convolutional denoising generative adversarial networks and multiple residual dense network, are proposed to obtain accurate channel state information, which can reflect the impact of different methods on the estimation performance. Simulation results reveal the evolution direction of these three methods and reveal their superior performance compared with existing benchmark schemes. Copyright © 2021, The Authors. All rights reserved.

关键词： Channel estimation

Two types of variational integrators and their equivalence

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arXiv 2018年

作者： Tang, Wensheng College of Mathematics and Statistics Changsha University of Science and Technology Changsha410114 China Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering Changsha410114 China

In this paper, we introduce two types of variational integrators, one originating from the discrete Hamilton’s principle while the other from Galerkin variational approach. It turns out that these variational integrators are equivalent to each other when they are used for integrating the classical mechanical system with Lagrangian function L(q,q) = 21qTMq−U(q) (M is an invertible symmetric constant matrix). They are symplectic, symmetric, possess super-convergence order 2s (which depends on the degree of the approximation polynomials), and can be related to continuous-stage partitioned Runge-Kutta methods. Copyright © 2018, The Authors. All rights reserved.

关键词： Galerkin methods

Chebyshev symplectic methods based on continuous-stage Runge-Kutta methods

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arXiv 2018年

We develop Chebyshev symplectic methods based on Chebyshev orthogonal polynomials of the first and second kind separately in this paper. Such type of symplectic methods can be conveniently constructed with the newly-built theory of weighted continuous-stage Runge-Kutta methods. A few numerical experiments are well performed to verify the efficiency of our new methods. Copyright © 2018, The Authors. All rights reserved.

关键词： Runge Kutta methods

Triple-function Hydrated Eutectic Electrolyte for Enhanced Aqueous Zinc Batteries

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Angewandte Chemie 2023年第40期135卷

作者： Yunpeng Zhong Xuesong Xie Prof. Zhiyuan Zeng Prof. Bingan Lu Prof. Gen Chen Prof. Jiang Zhou School of Materials Science and Engineering Hunan Provincial Key Laboratory of Electronic Packaging and Advanced Functional Materials Central South University Changsha Hunan 410083 P. R. China Contribution: Conceptualization (equal) Data curation (lead) Formal analysis (lead) Investigation (equal) Methodology (lead) Writing - original draft (lead) Contribution: Formal analysis (supporting) Investigation (supporting) Validation (lead) Writing - review & editing (supporting) Department of Materials Science and Engineering City University of Hong Kong 83 Tat Chee Avenue Kowloon Hong Kong 999077 P. R. China Contribution: Formal analysis (supporting) Investigation (supporting) Writing - review & editing (supporting) School of Physics and Electronics Hunan University Changsha Hunan 410082 P. R. China Contribution: Data curation (supporting) Investigation (supporting) Writing - review & editing (supporting) Contribution: Conceptualization (equal) Formal analysis (supporting) Funding acquisition (supporting) Resources (lead) Supervision (equal) Validation (lead) Writing - review & editing (equal) Contribution: Conceptualization (equal) Funding acquisition (lead) Investigation (equal) Project administration (lead) Supervision (equal) Writing - review & editing (equal)

Aqueous rechargeable zinc-ion batteries (ARZBs) are impeded by the mutual problems of unstable cathode, electrolyte parasitic reactions, and dendritic growth of zinc (Zn) anode. Herein, a triple-functional strategy by introducing the tetramethylene sulfone (TMS) to form a hydrated eutectic electrolyte is reported to ameliorate these issues. The activity of H 2 O is inhibited by reconstructing hydrogen bonds due to the strong interaction between TMS and H 2 O. Meanwhile, the preferentially adsorbed TMS on the Zn surface increases the thickness of double electric layer (EDL) structure, which provides a shielding buffer layer to suppress dendrite growth. Interestingly, TMS modulates the primary solvation shell of Zn 2+ ultimately to achieve a novel solvent co-intercalation ((Zn-TMS) 2+ ) mechanism, and the intercalated TMS works as a “pillar” that provides more zincophilic sites and stabilizes the structure of cathode (NH 4 V 4 O 10 , (NVO)). Consequently, the Zn||NVO battery exhibits a remarkably high specific capacity of 515.6 mAh g −1 at a low current density of 0.2 A g −1 for over 40 days. This multi-functional electrolytes and solvent co-intercalation mechanism will significantly propel the practical development of aqueous batteries.

关键词： Double Electric Layer Electrochemistry Eutectic Electrolyte Hydrogen Bond Network Zinc Battery

Energy-preserving continuous-stage partitioned Runge-Kutta methods

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arXiv 2018年

作者： Tan, Wensheng College of Mathematics and Statistics Changsha University of Science and Technology Changsha410114 China Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering Changsha410114 China

In this paper, we present continuous-stage partitioned Runge-Kutta (csPRK) methods for energy-preserving integration of Hamiltonian systems. A sufficient condition for the energy preservation of the csPRK methods is derived. It is shown that the presented condition contains the existing condition for energy-preserving continuous-stage Runge-Kutta methods as a special case. A noticeable and interesting result is that when we use the simplifying assumptions of order conditions and the normalized shifted Legendre polynomials for constructing high-order energy-preserving csPRK methods, both the Butcher "weight" coefficients Bτ and Bbτ must be equal to 1. As illustrative examples, new energy-preserving integrators are acquired by virtue of the presented condition, and for the sake of verifying our theoretical results, some numerical experiments are reported. Copyright © 2018, The Authors. All rights reserved.

关键词： Runge Kutta methods

Energy-preserving continuous-stage Runge-Kutta-Nyström methods

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arXiv 2018年

Many practical problems can be described by second-order system q¨ = −M∇U(q), in which people give special emphasis to some invariants with explicit physical meaning, such as energy, momentum, angular momentum, etc. However, conventional numerical integrators for such systems will fail to preserve any of these quantities which may lead to qualitatively incorrect numerical solutions. This paper is concerned with the development of energy-preserving continuous-stage Runge-Kutta-Nyström (csRKN) methods for solving second-order systems. Sufficient conditions for csRKN methods to be energy-preserving are presented and it is proved that all the energy-preserving csRKN methods satisfying these sufficient conditions can be essentially induced by energy-preserving continuous-stage partitioned Runge-Kutta methods. Some illustrative examples are given and relevant numerical results are reported. Copyright © 2018, The Authors. All rights reserved.

关键词： Hamiltonians