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Modular assembly of complex C-alkyl glycoside enabled via cooperative NHC and photoredox catalysis

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Science China Chemistry 2025年

作者： rui-qiang Jiao Ming Li Xi chen Mei-Ze xu Tian ding Xiao-Ping Gong Zhuo-Mei Li xue-Yuan Liu Yong-Min Liang State Key Laboratory of Applied Organic Chemistry Lanzhou University College of Chemistry and Chemical Engineering Northwest Normal University

C-Alkyl glycosides are found in natural products and are indispensable in drug development programs,owing to their diverse range of medicinal ***-component reactions involving glycosyl radical addition are well documented and proved efficient for the C-alkyl glycosides ***,multicomponent reactions for the rapid and controllable construction of structurally diversified C-alkyl glycosides in a single step remains a significant challenge due to the issues associated with balancing reactivity,compatibility,and ***,we report an NHC and photoredox co-catalyzed three-component method to access complex and valuable C-alkyl *** protocol exhibits broad substrate scope and excellent chemoand ***,nine types of sugars are compatible with this *** addition,the generality of this catalytic strategy was further highlighted by the potential for scalable production,the feasibility of further modifications of the products and its successful application in the late-stage functionalization of pharmaceutical skeletons.

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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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Ground-high altitude joint detection of ozone and nitrogen oxides in urban areas of Beijing

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Journal of Environmental Sciences 2013年第4期25卷 758-769页

作者： Pengfei chen qiang Zhang jiannong Quan Yang Gao delong Zhao Junwang Meng Beijing Weather Modification Office Institute of Urban Meteorology China Meteorological AdministrationPost-Doctoral Scientific Research Workstation of Urban Meteorology and Urban Disasters

Based on observational data of ozone （O3） and nitrogen oxide （NOx） mixing ratios on the ground and at high altitude in urban areas of Beijing during a period of six days in November 2011, the temporal and spatial characteristics of mixing ratios were analyzed. The major findings include： urban O3 mixing ratios are low and NOx mixing ratios are always high near the road in November. Vertical variations of the gases are significantly different in and above the planetary boundary layer. The mixing ratio of O3 is negatively correlated with that of NOx and they are positively correlated with air temperature, which is the main factor directly causing vertical variation of O3 and NOx mixing ratios at 600-2100 m altitude. The NOx mixing ratios elevated during the heating period, while the O3 mixing ratios decreased： these phenomena are more significant at high altitudes compared to lower altitudes. during November, air masses in the urban areas of Beijing are brought by northwesterly winds, which transport O3 and NOx at low mixing ratios. due to Beijing＇s natural geographical location, northwest air currents arc beneficial to the dilution and dispersion of pollutants, which can result in lower O3 and NOx background values in the Beijing urban area.

关键词： atmospheric pollution ozone nitrogen oxides spatial distribution aircraft sound

Quasi-MOF-immobilized metal nanoparticles for synergistic catalysis

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Science China Chemistry 2020年第11期63卷 1601-1607页

作者： Liyu chen Nobuko Tsumori qiang xu AIST-Kyoto University Chemical Energy Materials Open Innovation Laboratory(ChEM-OIL) National Institute of Advanced Industrial Science and Technology(AIST)YoshidaSakyo-kuKyoto 606-8501Japan Toyama National College of Technology 13 Hongo-machiToyama 939-8630Japan School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002China

Through partial deligandation of metal-organic frameworks(MOFs),quasi-MOFs with a transition structure between MOFs and metal compounds(such as metal oxides,nitrides,sulfides,and phosphides)can be ***-MOFs can not only retain the porous structure of MOFs to a certain extent,but also expose the inorganic nodes to the guest species(e.g.,metal nanoparticles)to show enhanced metal-support interaction for synergistic *** concept was first demonstrated by our group through calcining Au/MIL-101 at different temperatures under Ar flow to adjust the interface between Au nanoparticles and the inorganic Cr–O *** obtained Au/quasi-MIL-101 showed superior enhanced catalytic activity in the oxidation of carbon *** study has inspired further research interest to fabricate other quasi-MOFs through controlled deligandation of mono-and bimetallic MOFs and their composites for the design of efficient catalysts.

关键词： MOFs metal nanoparticles metal-support interaction quasi-MOFs synergistic catalysis

Micro-mechanism of metal magnetic memory signal variation during fatigue

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International Journal of Minerals,Metallurgy and Materials 2014年第3期21卷 259-265页

作者： Ming-xiu xu Zhang-hua chen Min-qiang xu School of Mathematics and Physics University of Science and Technology Beijing division of Vehicle dynamics & Control Harbin Institute of Technology

Tensile fatigue tests were designed to study the relation between the tangential magnetic memory signal and dislocations. According to experimental results, in the early stage of fatigue, the magnetic signal and the dislocation density rapidly increase; while in the middle stage, the magnetic signal gradually increases, the dislocation density remains steady, and only the dislocation structure develops. On the other hand, in the later stage, the magnetic signal once again increases rapidly, the dislocation structure continues to develop, and microscopic cracks are formed. Analysis reveals that the dislocations block the movement of the domain wall, and the area of dislocation accumulation thus becomes an internal magnetic source and scatters a field outward. In addition, the magnetic memory field strengthens with increasing dislocation density and complexity of the dislocation structure. Accordingly, the dislocation pinning factor related with the dislocation density and the dislocation structure has been proposed to characterize the effect of dislocations on the magnetic memory signal. The magnetic signal strengthens with an increase in the dislocation pinning factor.

关键词： fatigue of materials metal magnetic memory dislocations magnetic fields

Coupled elasto-plasticity damage constitutive models for concrete

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第4期14卷 256-267页

作者： qiang xu Jian-yun chen Jing LI Gang xu State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology School of Civil and Hydraulic Engineering Dalian University of Technology Plan and design Institute of daqing Oilfield Communication Company

The paper is to design and construct a coupled elasto-plasticity damage constitutive model for *** on the energy dissipation principle,the Hsieh-Ting-chen four-parameter yield function is *** model can reflect different strength characteristics of concrete in tension and compression,and reduce the limitation and lacuna of the traditional damage constitutive models for ***,numerical test for concrete stress-strain relation under uniaxial tension and compression is ***,the damage process of concrete gravity dam is calculated and analyzed in seismic *** with other damage constitutive models,the proposed model contains only one unknown parameter and the other parameters can be found in the Hsieh-Ting-chen four-parameter yield *** same damage evolution law,which is used for tension and compression,is good for determining stress-strain constitutive and damage characteristics in complex stress *** coupled damage constitutive models can be applied in analyzing damage of concrete gravity dam and arch dam.

关键词： Concrete damage constitutive models Hsieh-Ting-chen four-parameter yield function Uniaxial tension Uniaxial compression Gravity dam Arch dam

Variability of SO_2 in an intensive fog in North China Plain:Evidence of high solubility of SO_2

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Particuology 2013年第1期11卷 41-47页

作者： qiang Zhang xuexi Tie Weili Lin Junji Cao jiannong Quan Liang ran Wanyun xu Beijing Weather Modification Office Key Laboratory of Aerosol SKLLQGInstitute of Earth EnvironmentChinese Academy of Sciences Center for Atmospheric research BoulderCOUSA Chinese Academy of Meteorological Science department of Atmospheric and Oceanic Sciences School of PhysicsPeking University

A field experiment was conducted in an intensive fog event between November 5 and November 8, 2009, in a heavily SO2-polluted area in North China Plain （NCP）, to measure SO2 and other air pollutants, liquid water content （LWC） of fog droplets, and other basic meteorological parameters. during the fog period, the concentrations of SO2 showed large variability, which was closely related to the LWC in the fog droplets. The averaged concentration of SO2 during non-fog periods was about 25 ppbv, while during the fog period, it rapidly reduced to about 4-7 ppbv. Such large reduction of SO2 suggested that a majority of SO2 （about 70%-80%） had reverted from gas to aqueous phase on account of the high solubility of SO2 in water in the fog droplets. However, the calculated gas to aqueous phase conversion was largely underestimated by merely using the Henry＇s Law constant of SO2, thus suggesting that aqueous reaction of SO2 in fog droplets might play some important role in enhancing the solubility of SO2. To simplify the phenomenon, an ＂effective solubility coefficient＂ is proposed in this study. This variability of SO2 measurement during the extensive fog event provides direct evidence of oxidation of SO2 in fog droplets, thus providing important implications for better understanding of the acidity in clouds, precipitation, and fogs in NCP, now a central environmental focus in China due to its rapid economic development.

关键词： Solubility of SO2 Fogs in the North China Plain Aqueous phase reactions

New artificial boundary condition for saturated soil foundations

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Earthquake Engineering and Engineering Vibration 2012年第1期11卷 139-147页

作者： xu qiang chen Jianyun Li Jing Fan Shuli State Key Lab.of Coastal and Offshore Eng. Dalian University of Technology Dalian 116023 China School of Civil and Hydraulic Eng. Dalian University of Technology Dalian 116023 China

Anew artificial boundary model based on multi-directional transmitting and viscous-spring artificial boundary theories is proposed to absorb stress waves in a saturated soil foundation in dynamic analysis. Since shear waves （S-waves） are the same in a saturated soil foundation and a single-phase medium foundation, a tangential visco-elastic boundary condition for a single-phase medium foundation can also be used for saturated soil foundations. Thus, the purpose of the artificial boundary proposed in this paper is primarily to absorb two types of P-waves in a saturated soil foundation. The main idea is that the stress of the P-waves in the saturated soil foundation is decomposed into two types. The first type of stress, δra＇ is absorbed by the first artificial boundary. The second type of stress, δrb, is balanced by the stress generated by the second artificial boundary. Ultimately, both types of P-waves （fast-P-waves and slow-P-waves） are absorbed by the artificial boundary model proposed in this paper. In particular, note that the fast-P-waves and slow-P-waves are absorbed at the position of the first boundary. Thus, the artificial boundary model proposed herein can simultaneously absorb P-fast waves, P-slow waves and shear waves. Finally, a numerical example is given to examine the proposed artificial boundary model, and the results show that it is very accurate.

关键词： multi-directional transmitting artificial boundary viscous-spring artificial boundary saturated soil foundation Biot's equations

MULTI-SCALE NUMErICAL MOdEL FOr SIMULATING CONCrETE MATErIAL BASEd ON FrACTAL THEOrY

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Acta Mechanica Solida Sinica 2013年第4期26卷 344-352页

作者： qiang xu Jianyun chen Jing Li Mingming Wang School of Civil and Hydraulic Eng. Dalian University of Technology State Key Lab. of Coastal and Ofshore Eng. Dalian University of Technology

A new multi-scale numerical model is presented using the fractal theory and adopting FEM to simulate the failure of *** relation between the fractal box dimension in large scale and the damage to concrete in small scale is *** the evolutionary process of elastic modulus and strength in small scale is ***,the multi-scale numerical model is proposed to describe the constitutive relation of concrete between small scale and large scale.A two-dimensional static analysis of a concrete block is performed by using this model and the calculation result is *** propagation of cracks of the concrete block is also studied.

关键词： fractal theory concrete material fractal box dimension damage multi-scale constitutive relation