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Deciphering fungal metabolon coupling tandem inverse-electrondemand Diels-Alder reaction and semipinacol rearrangement for the biosynthesis of spiro polycyclic alkaloids

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Science China Chemistry 2025年第01期 288-296页

作者： Shuai Liu Wen-Qiang Xu ying-Tong Di Man-cheng Tang Ding-Kang chen Ming-Ming Cao yao-Wen Chang Hong-yu Tang Chun-Mao yuan Jun-Bo yang Zhi-Li Zuo Han Guo Zi-fei Xu ying Zeng yun-Dong Wu Xiao-Jiang Hao Key Laboratory of Phytochemistry and Natural Medicines (Chinese Academy of Sciences) Kunming Institute of Botany Chinese Academy of Sciences University of Chinese Academy of Sciences Lab of Computational Chemistry and Drug Design State Key Laboratory of Chemical Oncogenomics Peking University Shenzhen Graduate School Shenzhen Bay Laboratory State Key Laboratory of Microbial Metabolism School of Life Sciences & Biotechnology Shanghai Jiao Tong University State Key Laboratory of Functions and Applications of Medicinal Plants Guizhou Medical University Molecular Biology Experimental Center Germplasm Bank of Wild Species in Southwest China Kunming Institute of Botany Chinese Academy of Sciences yunnan Key Laboratory for Wild Plant Resources Kunming Institute of Botany Chinese Academy of Sciences Research Unit of Chemical Biology of Natural Anti-Virus Products Chinese Academy of Medical Sciences

In the intricate process of natural product biosynthesis, a metabolon can enhance metabolic flux by associating sequential enzymes. A fungal metabolon, comprising of flavin-dependent monooxygenase Spe F and P450 monooxygenase Spe G, is identified in the biosynthesis of spiro polycyclic alkaloids(+)-notoamide B and its diastereomer(+)-versicolamide B. Using notoamide E as a substance, Spe F/Spe G metabolon can control the stereoselectivity of its 2,3-epoxidation, followed by hydrogen atom ion at C-17 to generate reactive epoxide tau-m A with dienyl iminium unit. Subsequently,(+)-notoamide B and(+)-versicolamide B are produced via tandem nonenzymatic inverse-electron-demand Diels-Alder reaction and semipinacol rearrangement. This provides the first example of metabolon in the biosynthesis of spiro-prenylated indole alkaloids.

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Promoting electrocatalytic alcohols oxidation coupled with H_(2) production via ligand intercalation strategy

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Nano Research 2023年第4期16卷 4596-4602页

作者： Li Li Zhiyuan Zhang Haotong chen fei chen College of New Materials and Chemical Engineering Beijing Key Lab of Special Elastomeric Composite MaterialsBeijing Institute of Petrochemical TechnologyBeijing 102617China

Electrochemical alcohol oxidation,the alternate of oxygen evolution reaction,has been recognized as an effective way to produce value-added chemicals coupled with H2 ***,the current researches still suffer from the low reaction rate and Faradaic efficiency(FE)that limits the overall ***,we report a ligand intercalation strategy to enhance the current density of alcohol electrooxidation by intercalating sodium dodecyl sulfonate(SDS)in the interlayer of Co(OH)_(2)catalyst(Co(OH)_(2)-SDS).For instance,the Co(OH)_(2)-SDS shows obviously enhanced current density for glycerol electrooxidation than that of pure Co(OH)_(2).The corresponding glycerol conversion rate and H2 production rate reach 0.35 mmol·cm^(−2)·h^(−1)and 9.1 mL·cm^(−2)·h^(−1)at 1.42 V *** hydrogen electrode,which are 2.2-and 1.9-fold higher than that of Co(OH)_(2).The yield of formate reaches 86.6%with selectivity of 95.3%at high glycerol conversion of 95.1%(with FE of 83.3%for glycerol oxidation).The Co(OH)_(2)-SDS is demonstrated efficient for different alcohols with enhanced *** confirmed that the intercalation of SDS in Co(OH)_(2)can promote the generation and exposure of CoOOH reactive sites,and also facilitate the adsorption of alcohol,thus enabling high reaction rate.

关键词： electrocatalysis alcohol oxidation hydrogen cobalt hydroxide ligand intercalation

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Dynamical brane creation and annihilation via a background flux

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Science China(Physics,Mechanics & Astronomy) 2022年第2期65卷 24-29页

作者： yi-fei chen Jian-Xin Lu Interdisciplinary Center for Theoretical Study University of Science and Technology of ChinaPeng Huanwu Center for Fundamental TheoryHefei 230026China

We study the dynamical Myers effect by allowing the fuzzy(or the dynamical dielectric brane)coordinates to be time *** find three novel kinds of the dynamical spherical dielectric branes depending on their respective excess *** first represents a dynamical spherical brane carrying a negative excess energy(having a lower bound)with its radius oscillating periodically between two given non-zero *** second is the one with zero excess energy and whose time dependence can be expressed in terms of a simple *** particular dynamical spherical configuration represents the dielectric brane creation and/or annihilation like a photon in the presence of a background creating an electron-position pair and then annihilating back to a *** third is the one carrying positive excess energy and the radius can also oscillate periodically between two non-zero values but,unlike the first kind,it passes zero twice for each *** of the above can also be interpreted as the time evolution of a semi-spherical D-brane–anti semi-spherical D-brane system.

关键词： dynamical Myers effect D-branes string/M-theory

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Multicase finite-time stabilization of stochastic memristor neural network with adaptive PI control

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Science China(Information Sciences) 2023年第12期66卷 121-137页

作者： fei WEI Guici chen Song ZHU Hubei Province Key Laboratory of System Science in Metallurgical Process Wuhan University of Science and Technology School of Mathematics China University of Mining and Technology

In this paper, a unified control framework is proposed to investigate the multicase finite-time stabilization of stochastic delayed memristor neural networks(SDMNNs). With this framework, stochastic finite-time stabilization(SFTS), stochastic fixed-time stabilization(SFXTS), and stochastic prescribed-time stabilization(SPTS) of SDMNNs are achieved. Subsequently, unlike existing results, a bridge between the proportional-integral(PI) control protocol and the SDMNN is established, allowing the system to perform SFTS/SFXTS/SPTS without a separately designed controller. By appropriately adjusting the control factors of the unified framework, appropriate time of settlement estimates is derived. Furthermore, the controller is improved to the appropriate adaptive controller using the PI control protocol. The SFTS/SFXTS/SPTS of the system are obtained, and the corresponding upper bounds for the estimation of the settling time functions are acquired. Finally, the feasibility of the obtained theoretical results is demonstrated by two examples.

关键词： stochastic delayed memristor neural networks multicase finite-time stabilization PI control adaptive PI control

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Stability analysis of hydro-turbine governing system based on machine learning

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Chinese Physics B 2021年第12期30卷 301-307页

作者： yuansheng chen fei Tong State Key Laboratory of Eco-hydraulic in Northwest Arid Region Xi’an University of TechnologyXi’an 710048China

Hydro-turbine governing system is a time-varying complex system with strong non-linearity,and its dynamic characteristics are jointly affected by hydraulic,mechanical,electrical,and other *** at the stability of the hydroturbine governing system,this paper first builds a dynamic model of the hydro-turbine governing system through mechanism modeling,and introduces the transfer coefficient characteristics under different load conditions to obtain the stability category of the *** neural network is used to perform the machine study and the predictive analysis of the stability of the system under different working conditions is carried out by using the additional momentum method to optimize the *** test set results show that the method can accurately distinguish the stability category of the hydro-turbine governing system(HTGS),and the research results can provide a theoretical reference for the operation and management of smart hydropower stations in the future.

关键词： hydro-turbine governing system stability machine learning dynamic model

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Shielding performance of metal fiber composites

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中国有色金属学会会刊：英文版 2004年第z1期14卷 493-496页

作者： chen Gang WU Bin chen Ze-fei Military Engineering Department Artillery Academy Hefei 230031 China Military Engineering Department Artillery Academy Hefei 230031 China College of Mechanical Engineering South China University of Technology Guangzhou 510640 China

Metal fibers have been applied to construct composites with desirable electromagnetic interference shiel ding effectiveness and mechanical properties. Copper and stainless steel fibers were prepared with micro-saw fiberpulling combined cutting method. The cross section of the fibers is hook-like, which is beneficial to the improvement of bonding strength. Cement-based composites with copper and stainless steel fibers were fabricated and their electromagnetic shielding effectiveness was measured in the frequency range of 1 - 5 GHz. The results show that the electromagnetic interference shielding effectiveness of those composites is enhanced by the addition of metal fibers,which functions mainly due to the absorption. At some frequencies, 20 dB or more difference is obtained between the materials with and without metal fibers.

关键词： metal fiber composites shielding performance

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THE TRUNCATED EM METHOD FOR JUMP-DIFFUSION SDDES WITH SUPER-LINEARLy GROWING DIFFUSION AND JUMP COEFFICIENTS

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Journal of Computational Mathematics 2024年第1期42卷 178-216页

作者： Shounian Deng chen fei Weiyin fei Xuerong Mao Key Laboratory of Advanced Perception and Intelligent Control of High-end Equipment Ministry of Educationand School of Mathematics-Physics and FinanceAnhui Polytechnic UniversityWuhu 241000China Business School University of Shanghai for Science and TechnologyShanghai 200093China Department of Mathematics and Statistics University of StrathclydeGlasgow G11XHUK

This work is concerned with the convergence and stability of the truncated EulerMaruyama(EM)method for super-linear stochastic differential delay equations(SDDEs)with time-variable delay and Poisson *** constructing appropriate truncated functions to control the super-linear growth of the original coefficients,we present two types of the truncated EM method for such jump-diffusion SDDEs with time-variable delay,which is proposed to be approximated by the value taken at the nearest grid points on the left of the delayed *** first type is proved to have a strong convergence order which is arbitrarily close to 1/2 in mean-square sense,under the Khasminskii-type,global monotonicity with U function and polynomial growth *** second type is convergent in q-th(qype *** addition,we show that the partially truncated EM method preserves the mean-square and H∞stabilities of the true ***,we carry out some numerical experiments to support the theoretical results.

关键词： SDDEs Truncated EM method Time-variable delay Poisson jumps

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Pinning synchronization of networked multi-agent systems: spectral analysis

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Control Theory and Technology 2015年第1期13卷 45-54页

作者： Linying XIANG fei chen Guanrong chen Department of Automation Xiamen University Department of Electronic Engineering City University of Hong Kong

Pinning synchronization of a networked multi-agent system with a directed communication topology is investigated from a spectral analysis approach. Some new types of synchronized regions for networked systems with different nonlinear agent dynamics and inner coupling structures are discovered. The eigenvalue distributions of the coupling and control matrices for different types of directed networks are obtained. The effects of the network topology, pinning density and pinning strength on the network synchronizability are examined through extensive numerical simulations. It is shown that the synchronizability of the pinned network can be effectively improved by increasing pinning density and pinning strength for some types of synchronized regions, whereas too large the pinning density and pinning strength will lead to desynchronization for other types. It is found that directed random networks are not always easier to synchronize than directed small-world networks, and a denser eigenvalue distribution may not always imply better synchronizability.

关键词： Multi-agent system directed network pinning control spectral analysis synchronizability synchronized region

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Rate-distortion weighted SPIHT algorithm for interferometer data processing

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Journal of Systems Engineering and Electronics 2011年第4期22卷 547-556页

作者： Jing Ma Jindong fei Dong chen Science and Technology on Space Systems Simulation Laboratory Beijing Simulation Center Beijing 100854 E R. China Institute of Telecommunication Satellite China Academy of Space Technology Beijing 100094 P. R. China

As one of the next generation imaging spectrometers, the interferential spectrometer （iS） possesses the advantages of high throughput, multi-channel and great resolution. The data of IS are produced in the spatial domain, but optical applications are in the Fourier domain. Traditional compression methods can only protect the visual quality of interferometer data in the spatial do- main but ignore the distortion in the Fourier domain. The relation between the distortion in the Fourier domain and the compression in the spatial domain is analyzed. By mathematical proof and val- idation with experiments, the relation between spatial and Fourier domains is discovered, and the significance in the Fourier domain is more important as optical path difference （OPD） increasing in the spatial domain. Based on this relation, a novel coding scheme is proposed, which can compress data in the spatial domain while reducing the distortion in the Fourier domain. In this scheme, the bit stream of the set partitioning in hierarchical trees （SPIHT） is truncated by adaptively lifting rate-distortion slopes according to the priorities of OPD based on rate-distortion optimization theory. Experimental results show that the proposed method can provide better protection of spectrum curves in the Fourier domain while maintaining a comparable visual quality in the spatial domain.

关键词： interferential spectrometer (IS) multi-spectrum compression set partitioning in hierarchical trees (SPIHT).

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Carbon nanotubes-Nafion composites as Pt-Ru catalyst support for methanol electro-oxidation in acid media

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Journal of Natural Gas Chemistry 2009年第2期18卷 199-204页

作者： Shengzhou chen fei ye Weiming Lin School of Chemistry and Chemical Engineering Guangzhou University Guangzhou 510006 Guangdong China School of Chemical and Energy Engineering South China University of Technology Guangzhou 510640 Guangdong China

Carbon nanotubes-Nafion （CNTs-Nation） composites were prepared by impregnated CNTs with Nation in ethanol solution and characterized by FT-IR. Pt-Ru catalysts supported on CNTs-Nafion composites were synthesized by microwave-assisted polyol process. The physical and electrochemical properties of the catalysts were characterized by X-ray diffraction （XRD）, transmission electron microscope （TEM）, CO stripping voltammetry, cyclic voltammetry （CV） and chronoamperometry （CA）. The results showed that the Nation incorporation in CNTs-Nation composites did not significantly alter the oxygen-containing groups on the CNTs surface. The Pt-Ru catalyst supported on CNTs-Nafion composites with 2 wt% Naton showed good dispersion and the best CO oxidation and methanol electro-oxidation activities.

关键词： carbon nanotubes-Nafion composites Pt-Ru catalysts methanol electro-oxidation

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