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Selective dissolution to synthesize densely populated Pt single atom catalyst

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Nano Research 2023年第1期16卷 219-227页

作者： weinan yang Xiaoguang Zhao Ya Wang Rong Wang Wenhao yang Yue Peng Junhua Li State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China Sinopec Research Institute of Petroleum Processing Beijing 100083China

Single atom catalysts(SACs)have become one of research focuses in heterogeneous catalysis for their effective utilization of active metal atoms and unique properties in various catalytic ***,due to their high surface energy,noble metal single atoms like Pt tend to migrate and agglomerate to form larger clusters or nanoparticles,which makes it a challenge to fabricate noble metal SACs with high loading(>5 wt.%).Furthermore,the decisive factors of loading maximum are still not ***,we reported a manganese oxide supported Pt SAC with a high loading of 5.6 wt.%synthesized by selective dissolution *** pre-stabilization of Pt by coordinated oxygen and the abundant surface defects of support are the determinants of high *** Pt SAC exhibited much better H_(2)spill-over and hydrocarbon oxidation abilities with lower adsorption and dissociation energies than the manganese oxide support because of its local electronic structure with less repulsion.

关键词： manganese oxide selective dissolution single-atom catalysis hydrogen spill-over propene oxidation

Metabolic engineering of a methyltransferase for production of drug precursors demecycline and demeclocycline in Streptomyces aureofaciens

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Synthetic and Systems Biotechnology 2020年第3期5卷 121-130页

作者： weinan yang Lingxin Kong Qing Wang Zixin Deng Delin You State Key Laboratory of Microbial Metabolism Joint International Research Laboratory of Metabolic and Developmental SciencesSchool of Life Sciences&BiotechnologyShanghai Jiao Tong UniversityShanghai200030China

Demecycline(DMTC)and demeclocycline(DMCTC)are C6-demethylated derivatives of tetracycline(TC)and chlortetracycline(CTC),*** are precursors of minocycline and tigecycline,which showed remarkable bioactivity against TC-resistant bacteria and have been used clinically for *** order to biosynthesize drug precursors DMTC and DMCTC,the function of a possible C-methyltransferase encoding gene ctcK was studied systematically in the CTC high-yielding industrial strain Streptomyces aureofaciens ***ΔctcK mutant accumulated two new products,which were turned out to be DMTC and ***,timecourse analysis of the fermentation products detected the epimers of DMTC and DMCTC transformed ***,an engineering strain with higher productivity of DMCTC was constructed by deleting ctcK and overexpressing ctcP of three extra copies *** of these two engineering strains not only served as a successful example of synthesizing required products through metabolic engineering,but also provided original strains for following elaborate engineering to synthesize more effective tetracycline derivatives.

关键词： Demecycline Demeclocycline Streptomyces aureofaciens F3 Metabolic engineering

Adaptive Optimal Output Regulation of Interconnected Singularly Perturbed Systems With Application to Power Systems

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 595-607页

作者： Jianguo Zhao Chunyu yang weinan Gao Linna Zhou Xiaomin Liu the Engineering Research Center of Intelligent Control for Underground Space Ministry of EducationChina University of Mining and TechnologyXuzhou 221116 the School of Information and Control Engineering China University of Mining and TechnologyXuzhou 221116 IEEE the State Key Laboratory of Synthetical Automation for Process Industries Northeastern UniversityShenyang 110819China

This article studies the adaptive optimal output regulation problem for a class of interconnected singularly perturbed systems(SPSs) with unknown dynamics based on reinforcement learning(RL).Taking into account the slow and fast characteristics among system states,the interconnected SPS is decomposed into the slow time-scale dynamics and the fast timescale dynamics through singular perturbation *** the fast time-scale dynamics with interconnections,we devise a decentralized optimal control strategy by selecting appropriate weight matrices in the cost *** the slow time-scale dynamics with unknown system parameters,an off-policy RL algorithm with convergence guarantee is given to learn the optimal control strategy in terms of measurement *** combining the slow and fast controllers,we establish the composite decentralized adaptive optimal output regulator,and rigorously analyze the stability and optimality of the closed-loop *** proposed decomposition design not only bypasses the numerical stiffness but also alleviates the *** efficacy of the proposed methodology is validated by a load-frequency control application of a two-area power system.

关键词： Adaptive optimal control decentralized control output regulation reinforcement learning(RL) singularly perturbed systems(SPSs)

High-efficiency 18S microalgae barcoding by coalescent,distance and character-based approaches: a test in Chlorella and Scenedesmus

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Journal of Oceanology and Limnology 2018年第5期36卷 1771-1777页

作者： ZOU Shanmei FEI Cong yang weinan HUANG Zheng HE Meilin WANG Changhai College of Resources and Environmental Science Nanjing A gricultural UniversityNanjing 210095China

The relatively conserved 18S is often used in the phylogenetic analysis of microalgae. However, whether it can really help in barcoding microalgae needs to be evaluated. In this study the multiple approaches of coalescent, distance and character-based barcoding are first employed in C hlorella and Scenedesmus to test the efficiency of 18S sequences for barcoding green microalgae. We show that most Chlorella and Scenedesmus species, including the cryptic species, can be distinguished by 18S sequences with all coalescent General Mixed Yule-coalescent(GMYC), poisson tree process(PTP), and P ID, distance(ABGD) and character-based approaches. Both GMYC and PTP analyses produce more genetic groups. The P ID and ABGD analyses only cluster some species. All species(apart from a few of lineages) can be separated in character-based barcoding analysis with more than three character attributes. In comparison with previous barcoding results with r bcL, tufA, ITS and 16 S, 18S produces good resolution in identifying Chlorella and Scenedesmus. Our results reveal that 18S is highly efficient in identifying taxa of green microalgae at species level, based on a combination of multiple barcoding approaches. Combining 18S with other gene markers may be useful in barcoding microalgae.

关键词： General Mixed Yule-coalescent (GMYC) poisson tree process (PTP) and PID distance (ABGD)character-based DNA barcoding microalgae 18S Chlorella Scenedesmus

A LuxR family transcriptional regulator AniF promotes the production of anisomycin and its derivatives in Streptomyces hygrospinosus ***

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Synthetic and Systems Biotechnology 2019年第1期4卷 40-48页

作者： Jufang Shen Lingxin Kong Yan Li Xiaoqing Zheng Qing Wang weinan yang Zixin Deng Delin You State Key Laboratory of Microbial Metabolism Joint International Research Laboratory of Metabolic and Developmental SciencesSchool of Life Sciences&BiotechnologyShanghai Jiao Tong UniversityShanghaiChina Department of Immunology Hebei Medical UniversityShijiazhuangHebeiChina

The protein synthesis inhibitor anisomycin features a unique benzylpyrrolidine system and exhibits potent selective activity against pathogenic protozoa and *** is one of the important effective components in Agricultural Antibiotic120,which has been widely used as naturally-originated agents for treatment of crop decay in *** chemical synthesis of anisomycin has recently been reported,but the complex process with low productivity made the biosynthesis still to be a vital mainstay in *** biosynthetic gene cluster(BGC)of anisomycin in Streptomyces hygrospinosus *** has been identified in our previous work,while poor understanding of the regulatory mechanism limited the yield enhancement via regulation engineering of *** *** this study here,we characterized AniF as an indispensable LuxR family transcriptional regulator for the activation of anisomycin *** genetic manipulations of aniF and the real-time quantitative PCR(RT-qPCR)revealed that it positively regulated the transcription of the anisomycin ***,the overexpression of aniF contributed to the improvement of the production of anisomycin and its *** of the mechanism underlying the function of AniF revealed that it directly activated the transcription of the genes aniR-G involved in anisomycin ***,one AniF-binding site in the promoter region of aniR was identified by DNase I footprinting assay and an inverted repeat sequence(5′-GGGC-3′)composed of two 4-nt half sites in the protected region was *** together,our systematic study confirmed the positive regulatory role of AniF and might facilitate the future construction of engineering strains with high productivity of anisomycin and its derivatives.

关键词： Anisomycin Agricultural Antibiotic120 Biosynthesis AniF LuxR regulator Streptomyces

Characterization of the positive SARP family regulator PieR for improving piericidin A1 production in Streptomyces piomogeues ***

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Synthetic and Systems Biotechnology 2019年第1期4卷 16-24页

作者： Yan Li Lingxin Kong Jufang Shen Qing Wang Qian Liu weinan yang Zixin Deng Delin You State Key Laboratory of Microbial Metabolism Joint International Research Laboratory of Metabolic and Developmental SciencesSchool of Life Sciences&BiotechnologyShanghai Jiao Tong UniversityShanghaiChina

Piericidin A1,a member ofɑ-pyridone antibiotic,exhibits various biological activities such as antimicrobial,antifungal,and antitumor properties and possesses potent respiration-inhibitory activity against insects due to its competitive binding capacity to mitochondrial complex *** biosynthetic pathway of piericidin A1 has been reported in Streptomyces piomogeues ***,while the regulatory mechanism remains poorly *** this study,a Streptomyces antibiotic regulatory protein(SARP)family transcriptional regulator PieR was *** disruption and complementation manipulations revealed that PieR positively regulated the production of piericidin ***,the overexpression of pieR contributed to the improvement of piericidin A1 *** real-time quantitative PCR(RT-qPCR)was carried out and the data showed that pieR stimulated the transcription of all the biosynthesis-related genes for piericidin *** order to explore the regulatory mechanism,electrophoresis mobility shift assays(EMSA)and DNase I footprinting experiments have been conducted.A protected region covering 50 nucleotides within the upstream region of pieR was identified and two 5-nt direct repeat sequences(5′-CCGGA-3′)in the protected region were *** findings,taken together,set stage for transcriptional control engineering in the view of optimizing piericidin A1 production and thus provide a viable potent route for the construction of strains with high productivity.

关键词： ɑ-pyridone antibiotic Transcriptional regulation SARP family regulator Secondary metabolic Streptomyces

A survey on model-based reinforcement learning

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Science China(Information Sciences) 2024年第2期67卷 59-84页

作者： Fan-Ming LUO Tian XU Hang LAI Xiong-Hui CHEN weinan ZHANG yang YU National Key Laboratory for Novel Software Technology Nanjing University Polixir. ai Department of Computer Science and Engineering Shanghai Jiao Tong University

Reinforcement learning(RL) interacts with the environment to solve sequential decision-making problems via a trial-and-error approach. Errors are always undesirable in real-world applications, even though RL excels at playing complex video games that permit several trial-and-error attempts. To improve sample efficiency and thus reduce errors, model-based reinforcement learning(MBRL) is believed to be a promising direction, as it constructs environment models in which trial-and-errors can occur without incurring actual costs. In this survey, we investigate MBRL with a particular focus on the recent advancements in deep RL. There is a generalization error between the learned model of a non-tabular environment and the actual environment. Consequently, it is crucial to analyze the disparity between policy training in the environment model and that in the actual environment, guiding algorithm design for improved model learning, model utilization, and policy training. In addition, we discuss the recent developments of model-based techniques in other forms of RL, such as offline RL, goal-conditioned RL, multi-agent RL, and meta-RL. Furthermore,we discuss the applicability and benefits of MBRL for real-world tasks. Finally, this survey concludes with a discussion of the promising future development prospects for MBRL. We believe that MBRL has great unrealized potential and benefits in real-world applications, and we hope this survey will encourage additional research on MBRL.

关键词： reinforcement learning model-based reinforcement learning planning model learning model learning with reduced error model usage

New Results in Cooperative Adaptive Optimal Output Regulation

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Journal of Systems Science & Complexity 2024年第1期37卷 253-272页

作者： DONG Yuchen GAO weinan JIANG Zhong-Ping State Key Laboratory of Synthetical Automation for Process Industries Northeastern UniversityShenyang 110819China Department of Electrical and Computer Engineering Tandon School of EngineeringNew York UniversityBrooklynNY 11201USA

This paper investigates the cooperative adaptive optimal output regulation problem of continuous-time linear multi-agent *** the multi-agent system dynamics are uncertain,solving regulator equations and the corresponding algebraic Riccati equations is challenging,especially for high-order *** this paper,a novel method is proposed to approximate the solution of regulator equations,i.e.,gradient descent *** is worth noting that this method obtains gradients through online data rather than model information.A data-driven distributed adaptive suboptimal controller is developed by adaptive dynamic programming,so that each follower can achieve asymptotic tracking and disturbance ***,the effectiveness of the proposed control method is validated by simulations.

关键词： Adaptive dynamic programming cooperative output regulation gradient descent method multi-agent systems.

Optimization of Random Feature Method in the High-Precision Regime

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Communications on Applied Mathematics and Computation 2024年第2期6卷 1490-1517页

作者： Jingrun Chen weinan E Yifei Sun School of Mathematical Sciences and Suzhou Institute for Advanced Research Suzhou 215006JiangsuChina University of Science and Technology of China Hefei 230026AnhuiChina Center for Machine Learning Research and School of Mathematical Sciences Peking UniversityBeijing 100871China AI for Science Institute Beijing 100084China School of Mathematical Sciences Soochow UniversitySuzhou 215006JiangsuChina

Machine learning has been widely used for solving partial differential equations(PDEs)in recent years,among which the random feature method(RFM)exhibits spectral accuracy and can compete with traditional solvers in terms of both accuracy and ***,the optimization problem in the RFM is more difficult to solve than those that arise in traditional *** the broader machine-learning research,which frequently targets tasks within the low-precision regime,our study focuses on the high-precision regime crucial for solving *** this work,we study this problem from the following aspects:(i)we analyze the coeffcient matrix that arises in the RFM by studying the distribution of singular values;(ii)we investigate whether the continuous training causes the overfitting issue;(ii)we test direct and iterative methods as well as randomized methods for solving the optimization *** on these results,we find that direct methods are superior to other methods if memory is not an issue,while iterative methods typically have low accuracy and can be improved by preconditioning to some extent.

关键词： Random feature method(RFM) Partial differential equation(PDE) Least-squares problem Direct method Iterative method