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On-demand molecular design for efficient blue phosphorescence

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Science China Chemistry 2024年第7期67卷 2124-2126页

作者： Meiqi dai Dongpeng Yan Beijing Key Laboratory of Energy Conversion and Storage Materials Key Laboratory of RadiopharmaceuticalsMinistry of EducationCollege of ChemistryBeijing Normal UniversityBeijing 100875China

Blue luminescence(including both fluorescence and phosphorescence)is one of the core elements in solid-state lighting and full-color *** to now,ultralong room temperature phosphorescence(RTP)with a long lifetime over 0.1.s has been continuously *** ultralong phosphorescence emission bands are in the region of 500 to600 ***,high-energy blue phosphorescence remains an immense challenge[1..

关键词： blue lifetime bands

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Amorphous hybrid tungsten oxide–nickel hydroxide nanosheets used as a highly efficient electrocatalyst for hydrogen evolution reaction

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Nano Research 2024年第4期17卷 2499-2508页

作者： Chao Lyu Chenghai dai Yiwei Tan State Key Laboratory of Materials-Oriented Chemical Engineering School of Chemistry and Chemical EngineeringNanjing Tech UniversityNanjing 211816China

There are more challenges for alkaline hydrogen evolution reaction(HER)via simultaneously expediting the electron-coupled water dissociation process(Volmer step)and the following electrochemical H_(2) desorption(Heyrovsky step).Hybrid amorphous electrocatalysts are highly desirable for efficient hydrogen evolution from water-alkali electrolyzers due to the bifunctionality for the different elementary steps of HER and optimal interactions with water molecules and the reactive hydrogen intermediates(Had).Herein,the synthesis of amorphous hybrid ultrathin(tungsten oxide/nickel hydroxide)hydrate(a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O)nanosheets on nickel foam(NF)for efficient alkaline HER is *** structural and composition features of a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O are characterized in *** resulting a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O/NF electrocatalyst with the synergistic effect of both hybrid components for the HER elementary steps shows greatly improved the activity and durability for the HER with a low overpotential of-41.and-1.3 mV at-1. and-500 mA·cm^(-2),respectively,a Tafel slope as low as-72.9 mV·dec^(-1.,and long-term stability of continuous electrolysis for at least 1.0 h accompanying by inappreciable overpotential change in 1.M *** the hybrid a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O,Ni(OH)_(2) and WO_(3) moieties are separately responsible for accelerating dissociative adsorption of water and weakening Had adsorption strength,which is beneficial to the improvement of the alkaline HER activity.

关键词： amorphous nanomaterial bimetallic electrocatalyst tungsten oxide ultrathin nanosheet hydrogen evolution reaction

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

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Research on Alliance Decision of Dual-Channel Remanufacturing Supply Chain Considering Bidirectional Free-Riding and Cost-Sharing

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Computer Modeling in Engineering & Sciences 2024年第9期140卷 2913-2956页

作者： Lina Dong Yeming dai School of Business Qingdao UniversityQingdaoChina

This study delves into the formation dynamics of alliances within a closed-loop supply chain(CLSC)that encom-passes a manufacturer,a retailer,and an e-commerce *** leverages Stackelberg game for this exploration,contrasting the equilibrium outcomes of a non-alliance model with those of three differentiated alliance *** non-alliance model acts as a crucial benchmark,enabling the evaluation of the motivations for various supply chain entities to engage in alliance *** analysis is centered on identifying the most effective alliance strategies and establishing a coordination within these *** thoroughly investigate the consequences of diverse alliance behaviors,bidirectional free-riding and cost-sharing,and the resultant effects on the optimal decision-making among supply chain *** findings underscore several pivotal insights:(1.The behavior of alliances within the supply chain exerts variable impacts on the optimal pricing and demand of its *** comparison to the non-alliance(D)model,the manufacturer-retailer(MR)and manufacturer-e-commerce platform(ME)alliances significantly lower both offline and online resale prices for new and remanufactured *** adjustment leads to an enhanced demand for products via the MR alliance’s offline outlets and the ME alliance’s online platforms,thereby augmenting the profits for those within the ***,retailer-e-commerce platform(ER)alliance tends to increase the optimal retail price and demand across both online and offline *** specific conditions,alliance behavior can also increase the profits of non-alliance members,and the profits derived through alliance channels also exceed those from non-alliance channels.(2)The prevalence of bidirectional free-riding behavior largely remains constant across different alliance *** these models,bidirectional free-riding typically elevates the equilibrium prices in offline channel while negatively affe

关键词： Dual-channel remanufacturing supply chain alliance remanufactured products bidirectional free-riding cost-sharing

Jackson-type inequalities on high-dimensional spheres

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Science China Mathematics 2024年第11期67卷 2571-2586页

作者： Yeli Niu Feng dai Department of Mathematics Shanghai Normal University Department of Mathematical and Statistical Sciences University of Alberta

We study Jackson's inequality on high-dimensional spheres with respect to the modulus of smoothness defined via the rotation *** obtain a version of Jackson's inequality with a dimensionfree constant,extending Newman and Shapiro's well-known results in 1.64 from the case of r = 1.and p = ∞ to more general *** results partially overcome the curse of *** also establish similar results on the equivalence of the K-functional and modulus of smoothness.

关键词： modulus of smoothness $K$-functional Jackson's inequality high-dimensional approximation

Pursue the nature of science: Advocate for a better research environment

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The Innovation 2024年第5期5卷 3-4页

作者： Ji dai Shenzhen Technological Research Center for Primate Translational Medicine Shenzhen-Hong Kong Institute of Brain ScienceShenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China CAS Key Laboratory of Brain Connectome and Manipulation the Brain Cognition and Brain Disease InstituteShenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China Guangdong Provincial Key Laboratory of Brain Connectome and Behavior Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China University of Chinese Academy of Sciences Beijing 100049China

WHAT IS REAL SCIENCE?Science is often viewed through the lens of its tangible outcomes—publications,grants,academic titles,and *** markers of success in the academic world are undoubtedly important and serve as measures of productivity and ***,focusing solely on these external rewards risks oversimplifying the true essence of science and overlooking its fundamental purpose—the pursuit of knowledge through a process of discovery.1.At its core,science is a systematic and methodical approach to understanding the natural world,unraveling its mysteries,and uncovering the underlying principles that govern the *** is a process of inquiry and exploration that is driven by curiosity,creativity,and a relentless quest for truth(Figure 1..Science is not merely a means to an end but a journey of discovery that transcends individual accomplishments and external *** example is the study of gravitational waves,which are ripples in the fabric of spacetime and are predicted by Einstein’s theory of general *** 201.,the Laser Interferometer Gravitational-Wave Observatory(LIGO)detected gravitational waves for the first *** a major scientific breakthrough was the result of a collaboration between physicists and engineers from multiple institutions around the world,and it was also the result of pure curiosity.

关键词： doubt breakthrough Figure

Rockburst criterion and evaluation method for potential rockburst pit depth considering excavation damage effect

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1649-1666页

作者： Jinhao dai Fengqiang Gong Lei Xu Engineering Research Center of Safety and Protection of Explosion & Impact of Ministry of Education (ERCSPEIME) Southeast UniversityNanjing211189China School of Civil Engineering Southeast UniversityNanjing211189China

Excavation-induced disturbances in deep tunnels will lead to deterioration of rock properties and formation of excavation damaged zone(EDZ).This excavation damage effect may affect the potential rockburst pit *** two diversion tunnels of Jinping II hydropower station for example,the relationship between rockburst pit depth and excavation damage effect is first *** results indicate that the rockburst pit depth in tunnels with severe damage to rock masses is relatively ***,the excavation-induced damage effect is characterized by disturbance factor D based on the Hoek-Brown criterion and wave velocity *** is found that the EDZ could be further divided into a high-damage zone(HDZ)with D=1.and weak-damage zone(WDZ),and D decays from one to zero *** this,a quantitative evaluation method for potential rockburst pit depth is established by presenting a three-element rockburst criterion considering rock strength,geostress and disturbance *** evaluation results obtained by this method match well with actual *** addition,the weakening of rock mass strength promotes the formation and expansion of potential rockburst *** potential rockburst pit depth is positively correlated with HDZ and WDZ depths,and the HDZ depth has a significant contribution to the potential rockburst pit depth.

关键词： Deep tunnel Rockburst Rockburst pit Excavation damage effect Hoek-Brown criterion

The Rate of Convergence of Augmented Lagrangian Method for Minimax Optimization Problems with Equality Constraints

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Journal of the Operations Research Society of China 2024年第2期12卷 265-297页

作者： Yu-Hong dai Li-Wei Zhang LSEC ICMSECAMSSChinese Academy of SciencesBeijing 100190China Institute of Operations Research and Control Theory School of Mathematical SciencesDalian University of TechnologyDalian 116024China

The augmented Lagrangian function and the corresponding augmented Lagrangian method are constructed for solving a class of minimax optimization problems with equality *** prove that,under the linear independence constraint qualification and the second-order sufficiency optimality condition for the lower level problem and the second-order sufficiency optimality condition for the minimax problem,for a given multiplier vectorμ,the rate of convergence of the augmented Lagrangian method is linear with respect to||μu-μ^(*)||and the ratio constant is proportional to 1.c when the ratio|μ-μ^(*)||/c is small enough,where c is the penalty parameter that exceeds a threshold c_(*)>O andμ^(*)is the multiplier corresponding to a local ***,we prove that the sequence of multiplier vectors generated by the augmented Lagrangian method has at least Q-linear convergence if the sequence of penalty parameters(ck)is bounded and the convergence rate is superlinear if(ck)is increasing to ***,we use a direct way to establish the rate of convergence of the augmented Lagrangian method for the minimax problem with a quadratic objective function and linear equality constraints.

关键词： Minimax optimization Augmented Lagrangian method Rate of convergence Second-order sufficiency optimality

Enhanced piezoelectric performance of Cr/Ta non-equivalent co-doped Bi_(4)Ti_(3)O_(1.)-based high-temperature piezoceramics

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Journal of Advanced Ceramics 2024年第3期13卷 263-271页

作者： Xuanyu Chen Ziqi Ma Bin Li Yejing dai School of Materials Sun Yat-sen UniversityShenzhen 518107China

In this study,(Cr_(1.3)/Ta_(2/3))non-equivalent co-doped Bi_(4)Ti_(3)O_(1.)(BIT)ceramics were prepared to solve the problem that high piezoelectric performance,high Curie temperature,and high-temperature resistivity could not be achieved simultaneously in BIT-based ceramics.A series of Bi_(4)Ti_(3-x)(Cr_(1.3)Ta_(2/3))_(x)O_(1.)(x=0-0.04)ceramics were synthesized by the solid-state reaction *** phase structure,microstructure,piezoelectric performance,and conductive mechanism of the samples were systematically *** B-site non-equivalent co-doping strategy combining high-valence Ta^(5+)and low-valence Cr^(3+)significantly enhances electrical properties due to a decrease in oxygen vacancy ***_(4)Ti_(2.97)(Cr_(1.3)Ta_(2/3))_(0.03)O_(1.)ceramics exhibit a high piezoelectric coefficient(d_(33)=26 pC·N^(-1.)and a high Curie temperature(TC=687℃).Moreover,the significantly increased resistivity(ρ=2.8×1.^(6)Ω·cm at 500℃)and good piezoelectric stability up to 600℃are also obtained for this *** the results demonstrate that Cr/Ta co-doped BIT-based ceramics have great potential to be applied in high-temperature piezoelectric applications.

关键词： high temperature piezoelectricity co-doped Bi_(4)Ti_(3)O_(1.)(BIT)