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Stereoselective synthesis of substituted 1,3-dienes from propargylic esters: electrophilic-metal or redox catalysis?

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Science China Chemistry 2024年第5期67卷 1384-1396页

作者： Mengfu Dai Liangliang song Liang-An Chen Jiangsu Collaborative Innovation Center of Biomedical Functional Materials Jiangsu Key Laboratory of New Power BatteriesSchool of Chemistry and Materials ScienceNanjing Normal UniversityNanjing 210023China Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources International Innovation Center for Forest Chemicals and MaterialsCollege of Chemical EngineeringNanjing Forestry UniversityNanjing 210037China

1,3-Diene architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials but also serve as versatile building blocks to furnish important functionalized molecules in synthetic chemistry due to conjugated repeating C=C units. Accordingly, various strategies to access substituted 1,3-dienes in a stereoselective manner have been developed. However, chemo-, regio-and stereoselective synthesis of highly substituted 1,3-dienes still remains elusive and challenging. Readily available propargylic esters have emerged as an appealing class of synthetic intermediates for accessing functionalized 1,3-dienes, especially challenging tri-or tetrasubstituted variants, via transition-metal catalysis, including electrophilic metal and redox neutral catalysis. This review, for the first time, systematically highlights recent advances in transitionmetal catalyzed synthesis of substituted 1,3-dienes from propargylic esters, discusses the mechanisms and synthetic utilities, and gives the remaining challenges and potential opportunities in this field.

关键词： 1 3-diene propargylic ester Lewis acid redox catalysis transition metal

Open-Shell Oligomers and Polymers: Theory, Characterization Methods, Molecular Design, and Applications

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Chinese Journal of Polymer Science 2024年第4期42卷 417-436页

作者： Xue-Qing Wang Cheng song Ting Lei Key Laboratory of Polymer Chemistry and Physics(Ministry of Education) School of Materials Science and EngineeringPeking UniversityBeijing100871China

Open-shell oligomers and polymers have exhibited intriguing electronic and magnetic properties, making them highly desirable for a wide range of applications, including ambipolar organic field-effect transistors (OFETs), photodetectors, organic thermoelectrics, and spintronics. Although open-shell ground states have been observed in certain small molecules and doped organic semiconductors, the exploration of open-shell ground-state conjugated polymers is still limited, and the strategies for designing these polymers remain obscure. This review aims to briefly introduce the theory and characterization methods of open-shell conjugated polymers, along with an overview of recent progress and applications. The objective is to stimulate further advancements and investigations in this promising area by shedding light on the potential of open-shell conjugated polymers and the challenges that lie ahead.

关键词： Conjugated polymers Open-shell molecules High-spin ground state Donor-acceptor(D-A)polymers Optoelectronic and magnetic properties

Strategic Study on the Development of Space Science in China and Proposals for Future Missions

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空间科学学报 2024年第4期44卷 699-703页

作者： WANG Chi song Tingting LI Ming CAO song National Space Science Center Chinese Academy of SciencesBeijing 100190

Since 2011,the Chinese Academy of Sciences(CAS)has implemented the Strategic Priority Program on Space Science(SPP).A series of scientific satellites have been developed and launched,such as Dark Matter Particle Explorer(DAMPE),Quantum Experiments at Space Scale(QUESS),Advanced Space-based Solar Observatory(ASO-S),Einstein Probe(EP),and significant scientific outcomes have been *** order to plan the future space science missions in China,CAS has organized the Chinese space science community to conduct medium and long-term development strategy studies,and summarized the major scientific frontiers of space science as“One Black,Two Dark,Three Origins and Five Characterizations”.Five main scientific themes have been identified for China’s future breakthroughs,including the Extreme Universe,Space-Time Ripples,the Panoramic View of the Sun and Earth,the Habitable Planets,and Biological&Physical Science in *** science satellite missions to be implemented before 2030 are proposed accordingly.

关键词： Space science Space missions Space exploration

Chemical vapor deposition making better lithium-sulfur batteries

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Science Bulletin 2024年第13期69卷 2013-2016页

作者： Yingze song Lixian song Menglei Wang Wenlong Cai State Key Laboratory of Environment-Friendly Energy Materials School of Materials and ChemistrySouthwest University of Science and TechnologyMianyang 621010China School of Material Science and Engineering Henan University of TechnologyZhengzhou 450001China Department of Advanced Energy Materials College of Materials Science and EngineeringSichuan UniversityChengdu 610064China

The burgeoning demand for modern electronic devices and electric vehicles has driven the development of efficient,reliable,and environmentally friendly batteries[1,2].Lithium–sulfur(Li–S)batteries with high theoretical capacity(1672 mA h g1)and energy density(2600 W h kg1),have garnered significant interest in both academic and industrial research[3,4].However,the widespread production and commercialization of Li–S batteries are impeded by the inherent characteristics of sulfur and lithium,along with their complex electrochemical ***,challenges such as the polysulfide shuttle effect and the slow kinetics of the sulfur nucleation/decomposition reaction hinder capacity utilization and cycling *** overcome these challenges,innovative electrocatalyst strategies aimed at enhancing activity have been explored.

关键词： lithium overcome cycling

Evaluating quality of motion for unsupervised video object segmentation

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Optoelectronics Letters 2024年第6期20卷 379-384页

作者： CHENG Guanjun song Huihui Jiangsu Key Laboratory of Big Data Analysis Technology Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment TechnologyNanjing University of Information Science&TechnologyNanjing 210044China12

Current mainstream unsupervised video object segmentation(UVOS) approaches typically incorporate optical flow as motion information to locate the primary objects in coherent video frames. However, they fuse appearance and motion information without evaluating the quality of the optical flow. When poor-quality optical flow is used for the interaction with the appearance information, it introduces significant noise and leads to a decline in overall performance. To alleviate this issue, we first employ a quality evaluation module(QEM) to evaluate the optical flow. Then, we select high-quality optical flow as motion cues to fuse with the appearance information, which can prevent poor-quality optical flow from diverting the network's attention. Moreover, we design an appearance-guided fusion module(AGFM) to better integrate appearance and motion information. Extensive experiments on several widely utilized datasets, including DAVIS-16, FBMS-59, and You Tube-Objects, demonstrate that the proposed method outperforms existing methods.

关键词： Evaluating quality of motion for unsupervised video object segmentation

Bactericidal bissulfone B7 targets bacterial pyruvate kinase to impair bacterial biology and pathogenicity in plants

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Science China(Life Sciences) 2024年第2期67卷 391-402页

作者： Awei Zhang Haizhen Zhang Ronghua Wang Hongfu He Baoan song Runjiang song National Key Laboratory of Green Pesticide Key Laboratory of Green Pesticide and Agricultural BioengineeringMinistry of EducationCenter for R&D of Fine Chemicals of Guizhou UniversityGuiyang 550025China

The prevention and control of rice bacterial leaf blight(BLB)disease has not yet been achieved due to the lack of effective agrochemicals and available ***,we develop a series of novel bissulfones and a novel target with a unique mechanism to address this *** developed bissulfones can control Xanthomonas oryzae ***(Xoo),and 2-(bis(methylsulfonyl)methylene)-N-(4-chlorophenyl)hydrazine-1-carboxamide(B_(7))is more effective than the commercial drugs thiodiazole copper(TC)and bismerthiazol(BT).Pyruvate kinase(PYK)in Xoo has been identified for the first time as the target protein of our bissulfone B_(7).PYK modulates bacterial virulence via a CRP-like protein(Clp)/two-component system regulatory protein(reg R)*** elucidation of this pathway facilitates the use of B_(7)to reduce PYK expression at the transcriptional level,block PYK activity at the protein level,and impair the interaction within the PYK-Clp-reg R complex via competitive inhibition,thereby attenuating bacterial biology and *** study offers insights into the molecular and mechanistic aspects underlying anti-Xoo strategies that target *** believe that these valuable discoveries will be used for bacterial disease control in the future.

关键词： 2-bissulfone-N-phenylhydrazine-1-carboxamide derivatives Xoo antibacterial activities pyruvate kinase regulatory mechanism

Optimizing profile line interval for enhanced accuracy in rock joint morphology and shear strength assessments

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International Journal of Mining Science and Technology 2024年第5期34卷 587-608页

作者： Leibo song Quan Jiang Shigui Du Jiamin song Gang Wang Yanting Gu Xingkai Wang Jinzhong Wu School of Civil Engineering Shaoxing UniversityShaoxing 312000China Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province Shaoxing UniversityShaoxing 312000China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China Institute of Rock Mechanics Ningbo UniversityNingbo 315211China

2D profile lines play a critical role in cost-effectively evaluating rock joint properties and shear ***, the interval(ΔI_(L)) between these lines significantly impacts roughness and shear strength assessments. A detailed study of 45 joint samples using four statistical measures across 500 different ΔI_(L)values identified a clear line interval effect with two stages: stable and *** statistical analysis showed a linear relationship between the error bounds of four parameters,shear strength evaluation, and their corresponding maximum ΔI_(L)values, where the gradient k of this linear relationship was influenced by the basic friction angle and normal stress. Accounting for these factors,lower-limit linear models were employed to determine the optimal ΔI_(L)values that met error tolerances(1%–10%) for all metrics and shear strength. The study also explored the consistent size effect on joints regardless of ΔI_(L)changes, revealing three types of size effects based on morphological ***, larger joints required generally higher ΔI_(L)to maintain the predefined error limits, suggesting an increased interval for large joint analyses. Consequently, this research provides a basis for determining the optimal ΔI_(L), improving accuracy in 2D profile line assessments of joint characteristics.

关键词： Rock joint Roughness Shear strength Size effect Profile line interval effect

On-chip physiological mimicry of neurovascular unit: challenges and perspectives

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Neural Regeneration Research 2024年第3期19卷 499-500页

作者： song Ih Ahn YongTae Kim School of Mechanical Engineering Pusan National UniversityBusanSouth Korea George W.Woodruff School of Mechanical Engineering Georgia Institute of TechnologyAtlantaGAUSA Parker H.Petit Institute for Bioengineering and Bioscience Georgia Institute of TechnologyAtlantaGAUSA Wallace H.Coulter Department of Biomedical Engineering Georgia Institute of TechnologyAtlantaGAUSA Institute for Electronics and Nanotechnology Georgia Institute of TechnologyAtlantaGAUSA

Neurological disorders including neurodegenerative diseases,brain tumors,and stroke are the second leading cause of death and the greatest cause of disability ***,it remains challenging to achieve effective drug delivery to the central nervous system for treatments of neurological diseases due to the blood-brain barrier(BBB).The function of the BBB is regulated by the physiological interactions between various types of cells in the neurovascular unit(NVU).In the NVU,the brain vasculature of the BBB is surrounded by brain pericytes,brain astrocytes,neurons,and microglia(Figure 1).Moreover,the NVU at the levels of arteries and veins includes contractile smooth muscle cells(Schaeffer and Iadecola,2021).

关键词： diseases death arteries

Stationary Almost Markov ε-Equilibria for Discounted Stochastic Games with Borel Spaces and Unbounded Payoffs

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Journal of Systems Science & Complexity 2024年第4期37卷 1672-1684页

作者： WU Yiting ZHANG Junyu HUANG song School of Mathematics Sun Yat-Sen UniversityGuangzhou 510275China School of Software and Microelectronics Peking UniversityBeijing 100871China

This paper is concerned with nonzero-sum discrete-time stochastic games in Borel state and action spaces under the expected discounted payoff *** payoff function can be *** transition probability is a convex combination of finite probability measures that are dominated by a probability measure on the state space and depend on the state *** suitable conditions,the authors establish the existence of stationary almost Markov ε-equilibria and give an approximation method via some stochastic games with bounded ***,a production game is introduced to illustrate the applications of the main result,which generalizes the bounded payoff case.

关键词： Almost Markovε-equilibrium Borel state space expected discounted payoff criterion nonzero-sum stochastic games unbounded payoffs