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Large time behavior of solutions for a class of time-dependent Hamilton-Jacobi equations

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Science China Mathematics 2016年第5期59卷 875-890页

作者： liU QiHuai li xinxiang yan jun School of Mathematical Sciences Fudan University School of Mathematics and Computing Sciences Guilin University of Electronic Technology Department of Mathematics Shanghai University

We study the long-time behavior of viscosity solutions for time-dependent Hamilton-Jacobi equations by the dynamical approach based on weak KAM(Kolmogorov-Arnold-Moser) theory due to Fathi. We establish a general conv... 详细信息

关键词： asymptotic behavior viscosity solution weak KAM theory Hamilton-Jacobi equation

Synthesis of chiral phosphine derivatives through a copper（I）-catalyzed desymmetric SNAr reaction

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Science China Chemistry 2025年

作者： Shuai Zhang Pei-Zhi liu yan-Bo li Qi Zhang jun-Zhao Xiao Yi-Fan Wang Tian-Yu Wei Jia-Wei Jiang Ye Wang Qian Peng liang Yin Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials Shanghai Institute of Organic Chemistry University of Chinese Academy of Sciences Chinese Academy of Sciences State Key Laboratory of Elemento-Organic Chemistry and Tianjin Key Laboratory of Biosensing and Molecular Recognition College of Chemistry Frontiers Science Center for New Organic Matter Nankai University Haihe Laboratory of Sustainable Chemical Transformations

Axially chiral phosphines are a class of extremely important ligands in asymmetric catalysis. Herein, an unprecedented copper（I）-catalyzed asymmetric SNAr reaction with HP（S）R2is uncovered, which delivers a series of axially chiral phosphine derivatives in high yields with excellent enantioselectivity. Furthermore, the diastereoselective reaction with the kinetic resolution of racemic HP（S）ArR proceeds smoothly, providing the products with moderate diastereoselectivity and excellent enantioselectivity. Control experiments indicate that HP（S）Ph2is much more active than HPPh2and HP（O）Ph2as the pronucleophile in the present reaction. It is found that the SNAr reaction （the first SNAr） proceeds in a desymmetric manner, providing the desired chiral products while a continued SNAr reaction （the second SNAr） slightly occurs in a kinetic resolution manner in the present catalytic system, which enhances the ee of the desired chiral products. DFTcalculations support a concerted reaction pathway rather than a step-wise mechanism. Finally, axially chiral olefin-phosphines produced by the present method work as suitable ligands in Pdcatalyzed asymmetric allylic substitution with C-, N-, and O-nucleophiles and Rh-catalyzed asymmetric addition of arylboronic acid to benzil.

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Persistent alterations in gray matter in COVID-19 patients experiencing sleep disturbances:a 3-month longitudinal study

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Neural Regeneration Research 2025年第10期20卷 3013-3024页

作者： Kaixuan Zhou Gaoxiong Duan Ying liu Bei Peng Xiaoyan Zhou lixia Qin lingyan liang Yichen Wei Qingping Zhang Xiaocheng li Haixia Qin Yinqi Lai Yian Lu yan Zhang Jiazhu Huang Jinli Huang Yinfei Ouyang Bolin Bin Mingming Zhao jun liu Jianrong yang Demao Deng Guangxi Key Laboratory of Special Biomedicine School of MedicineGuangxi UniversityNanningGuangxi Zhuang Autonomous RegionChina Department of Radiology the People’s Hospital of Guangxi Zhuang Autonomous RegionGuangxi Academy of Medical SciencesNanningGuangxi Zhuang Autonomous RegionChina Department of Sleep Medicine the People’s Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxi Zhuang Autonomous RegionChina Department of Radiology The Second Xiangya HospitalCentral South UniversityChangshaHunan ProvinceChina Guangxi Clinical Research Center for Sleep Medicine the People’s Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxi Zhuang Autonomous RegionChina

Sleep disturbances are among the most prevalent neuropsychiatric symptoms in individuals who have recovered from severe acute respiratory syndrome coronavirus 2 *** studies have demonstrated abnormal brain structures in patients with sleep disturbances who have recovered from coronavirus disease 2019(COVID-19).However,neuroimaging studies on sleep disturbances caused by COVID-19 are scarce,and existing studies have primarily focused on the long-term effects of the virus,with minimal acute phase *** a result,little is known about the pathophysiology of sleep disturbances in the acute phase of *** address this issue,we designed a longitudinal study to investigate whether alterations in brain structure occur during the acute phase of infection,and verified the results using 3-month follow-up data.A total of 26 COVID-19 patients with sleep disturbances(aged 51.5±13.57 years,8 women and 18 men),27 COVID-19 patients without sleep disturbances(aged 47.33±15.98 years,9 women and 18 men),and 31 age-and gender-matched healthy controls(aged 49.19±17.51 years,9 women and 22 men)were included in this *** COVID-19 patients with sleep disturbances were included in a longitudinal *** found that COVID-19 patients with sleep disturbances exhibited brain structural changes in almost all brain *** cortical thicknesses of the left pars opercularis and left precuneus were significantly negatively correlated with Pittsburgh Sleep Quality Index ***,we observed changes in the volume of the hippocampus and its subfield regions in COVID-19 patients compared with the healthy *** 3-month follow-up data revealed indices of altered cerebral structure(cortical thickness,cortical grey matter volume,and cortical surface area)in the frontal-parietal cortex compared with the baseline in COVID-19 patients with sleep *** findings indicate that the sleep disturbances patients had altered morphology in the cortical an

关键词： brain structure cortical gray matter volume cortical surface area cortical thickness hippocampus magnetic resonance imaging Pittsburgh Sleep Quality Index severe acute respiratory syndrome coronavirus 2 infections sleep disturbances sub-cortical volume

Engineering N3C vacancies in hierarchical porous carbon nitride nanosheets for room temperature ultradeep photocatalytic aerobic oxidative desulfurization

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Science China Chemistry 2025年

作者： Yina Nie Weijie yang Xin Wang Xiang li Lele Wei Xiaolin Bai lin liu Feng Fu jun Wan College of Chemistry & Chemical Engineering Research Institute of Comprehensive Energy Industrial Technology Shaanxi Key Laboratory of Chemical Reaction Engineering Yan'an University Anhui Engineering Research Center of Carbon Neutrality College of Chemistry and Materials Science Anhui Normal University

The production of ultra-low sulfur clean fuels holds global significance for improving energy efficiency and reducing environmental pollution. Photocatalytic aerobic oxidative desulfurization（PODS） offers an attractive approach to efficiently remove refractory heterocyclic aromatic sulfur compounds under mild conditions. However, the sluggish charge dynamics,insufficient molecule activation, and slow mass transfer within photocatalysts restrict the overall desulfurization efficiency,hindering the widespread application of this technology. Herein, we developed a defective g-C3N4（M1U3CN） photocatalyst with bridged N3Cvacancies and hierarchical porous structures to address these limitations. This catalyst not only demonstrates outstanding dibenzothiophene（DBT） removal efficiency of 99.6% for model oil with high conversion and selectivity but also achieves complete sulfur removal from gasoline as well as 96.7% sulfur removal for distilled diesel at room temperature,successfully achieving ultradeep aerobic oxidative desulfurization. The introduction of rich N3Cvacancies and abundant micromeso-macroporous distribution in M1U3CN enhances kinetic efficiencies by promoting charge carrier separation, mass transfer,and molecular activation simultaneously; resulting in exceptional PODS performance. This work provides a collaborative strategy to overcome kinetic challenges in aerobic oxidative desulfurization via defect and structural engineering of the catalyst.

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Strategic integration of 2D perovskite and chiral quantum dot hybrid heterostructures for superior CPL detection

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Science China Technological Sciences 2025年第1期 368-377页

作者： Jiahe yan Xi ZHANG Lei liU Hualin BI Mengke WANG Jing li jun WANG Department of Chemistry College of SciencesNortheastern University Technical Institute of Physics and Chemistry Chinese Academy of Sciences

Circularly polarized light（CPL） detection has garnered significant research interest due to its extensive applications in optoelectronics and quantum *** perovskites possess CPL detection capabilities due to their inherent ***,incorporating organic amine spacers distorts the crystal lattice,resulting in defects that reduce the sensitivity of CPL *** study introduces the concept of chiral superposition for the first time,reporting two mixed heterostructures composed of two-dimensional（2D） chiral perovskite（R/S-MBA）2MAPb2I7（R/S）,chiral quantum dots（R/S-MBA）-CsPbBr3（R/SQD）,and chiral carbon dots（Ch-CDs）.The addition of chiral quantum dots/Ch-CDs fills the defects of the chiral perovskite films and reduces the electron-hole recombination rate in chiral hybrid perovskites,thereby significantly enhancing the circularly polarized sensitivity of the CPL *** adjusting the concentration of chiral quantum dots,controllability of spin electron transfer is achieved,which has a notable impact on circular dichroism（CD） and anisotropy factor *** anisotropy factor glhpof the mixed heterostructure R/S-R/SQD is approximately 21.58 times higher than that of single-phase chiral perovskites,and the asymmetry factor gCDincreases ***,this work opens up a new effective pathway for achieving high-sensitivity CPL detection,with promising applications in optoelectronic technologies such as spin information communication and quantum optics.

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An SOR Implicit Time-accurate Scheme in Calculating Unsteady Flows

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Chinese Journal of Aeronautics 2007年第3期20卷 202-209页

作者： li Yue-jun yan Chao School of Aeronautic Science and Engineering Beijing University of 4eronautics andAstronautics Beijing 100083 China

A new time-accurate marching scheme for unsteady flow calculations is proposed in the present work. This method is the combination of classical Successive Over-Relaxation （SOR） iteration method and Jacobian matrix diagonally dominant splitting method of LUSGS. One advantage of this algorithm is the second-order accuracy because of no factorization error. Another advantage is the low computational cost because the Jacobian matrices and fluxes are only calculated once in each physical time step. And, the SOR algorithm has better convergence property than Gauss-Seidel. To investigate its accuracy and convergency, several unsteady flow computational tests are carded out by using the proposed SOR algorithm. Roe＇s FDS scheme is used to discritize the inviscid flux terms. Unsteady computational results of SOR are compared with the experiment results and those of Gauss-Seidel, Results reveal that the numerical results agree well with the experimental data and the second-order accuracy can be obtained as the Gauss-Seidel for unsteady flow computations. The impact of SOR factor is investigated for unsteady computations by using different SOR factors in this algorithm to simulate each computational test. Different numbers of inner iterations are needed to converge to the same criterion for different SOR factors and optimal choice of SOR factor can improve the computational efficiency greatly.

关键词： unsteady flow SOR algorithm SOR factor Gauss-Seidel

The CRISPR/Cas9 revolution continues: From base editing to prime editing in plant science

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Journal of Genetics and Genomics 2021年第8期48卷 661-670页

作者： yan li Wenjing li jun li State Key Laboratory of North China Crop Improvement and Regulation College of Life SciencesHebei Agricultural UniversityBaodingHebei 071001China College of life Sciences Capital Normal UniversityBeijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental ImprovementBeijing 100048China

The ability to precisely inactivate or modify genes in model organisms helps us understand the mysteries of life. Clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9(Cas9), a revolutionary technology that could generate targeted mutants, has facilitated notable advances in plant science. Genome editing with CRISPR/Cas9 has gained great popularity and enabled several technical breakthroughs. Herein, we briefly introduce the CRISPR/Cas9, with a focus on the latest breakthroughs in precise genome editing(e.g., base editing and prime editing), and we summarize various platforms that developed to increase the editing efficiency, expand the targeting scope, and improve the specificity of base editing in plants. In addition, we emphasize the recent applications of these technologies to plants. Finally, we predict that CRISPR/Cas9 and CRISPR/Cas9-based genome editing will continue to revolutionize plant science and provide technical support for sustainable agricultural development.

关键词： CRISPR/Cas9 Base editing Prime editing Loss-of-function Gain-of-function DNA free

Functionalized metal-organic frameworks with strong acidity and hydrophobicity as an efficient catalyst for the production of 5-hydroxymethylfurfural

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Chinese Journal of Chemical Engineering 2021年第5期34卷 167-174页

作者： Huan li Yao Zhong Luxi Wang Qiang Deng jun Wang Zheling Zeng xinxiang Cao Shuguang Deng Key Laboratory of Poyang Lake Environment and Resource Utilization(Nanchang University)of the Ministry of Education School of ResourceEnvironmental and ChemicalEngineeringNanchang UniversityNanchang 330031China Laboratory for Development&Application of Cold Plasma Technology College of Chemistry and Chemical EngineeringLuoyang Normal UniversityLuoyang 471022China School for Engineering of Matter Transport and EnergyArizona State University551 E.Tyler MallTempeAZ 85287United States

In the dehydration of fructose to 5-hydroxymethyl furfural(HMF),in situ produced water weakens the acid strength of the catalyst and causes the rehydration of HMF,causing unsatisfactory catalytic activity and *** this work,a class of benzenesulfonic acid-grafted metal-organic frameworks with strong acidity and hydrophobicity is obtained by the direct sulfonation method using 4-chlorobenzenesulfonic acid as sulfonating *** resultant MOFs have a specific surface area of greater than 250 m^(2)·g^(-1),acid density above 1.0 mmol·g^(-1),and water contact angle up to 129°.The hydrophobic MOF-PhSO_(3)H exhibits both higher catalytic activity and selectivity than MOF-SO_(3)H in the HMF synthesis due to its better hydrophobicity and ***,the catalyst has a high recycled *** last,fructose is completely converted,and 98.0%yield of HMF is obtained under 120℃ in a DMSO solvent *** successful preparation of the hydrophobic acidic MOF provides a novel hydrophobic catalyst for the synthesis of HMF.

关键词： Catalysis Catalyst Biomass Metal-organic framework Fructose 5-Hydroxymethylfurfural

Effects of tooth bending damage on the leakage performance and rotordynamic coefficients of labyrinth seals

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Chinese Journal of Aeronautics 2020年第4期33卷 1206-1217页

作者： Yaoxing CHEN Zhigang li jun li Xin yan Institute of Turbomachinery Xi’an Jiaotong UniversityXi'an 710049China Collaborative Innovation Center for Advanced Aero-Engine Beijing 100083China

Tooth bending damage resulting from an intense impact by the rotor sometimes occurs in the transient *** investigate the influence of after-damage clearance and tooth bending length on the leakage performance and rotordynamic coefficients of labyrinth seals,three tooth bending damages were taken into consideration,including the unbent tooth damage(abbreviated as Unbent),the partial tooth bending damage(abbreviated as Pbent)and the complete tooth bending damage(abbreviated as Cbent).The transient CFD solution was utilized to calculate the leakage flow rates and rotordynamic coefficients of labyrinth seals with clearances of 0.3,0.4,0.5,0.6 mm for three tooth bending *** obtained result shows that the Unbent tooth damage leaks least while the Pbent tooth bending damage leaks most,and an increase of 6.1%for Cbent tooth bending damage and an increase of 19.4%for Pbent tooth bending damage are discovered at the tooth clearance of 0.6 mm in comparison with the Unbent tooth *** to the Unbent tooth damage,the effective damping for Pbent tooth bending damage and Cbent tooth bending damage is lower and drops by 9.7%–33.6%and 8.5%–22.6%respectively at the tooth clearance of 0.6 mm,suggesting that Pbent tooth bending damage or Cbent tooth bending damage tends to weaken the seal stability when compared to the Unbent tooth damage.

关键词： Labyrinth seal Leakage Rotor forward whirl Rotordynamic coefficients Tooth bending damage Vena contracta effect