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Construction of remote cyano-substituted quaternary carbon centers via nickel-catalyzed migratory hydrocyanation of unconjugated dienes

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Science China Chemistry 2024年第10期67卷 3397-3405页

作者： Yidan xing Rongrong Yu Mingdong Jiao Ting Wang Xianjie Fang Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs School of Chemistry and Chemical EngineeringShanghai Jiao Tong University Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education Key Laboratory of Organosilicon Material Technology of Zhejiang ProvinceCollege of MaterialChemistry and Chemical EngineeringHangzhou Normal University

The transition-metal-catalyzed migratory functionalization has emerged as a robust protocol for the building of C–C bonds remote from the “initiation” position. However, a similar strategy for the construction of quaternary carbon centers is still underdeveloped and only a limited number of reports exist. Herein, we report a nickel-catalyzed migratory hydrocyanation of unconjugated dienes to construct remote cyano-substituted quaternary carbon centers. This transformation features exceptional regioselectivity, mild reaction conditions, broad substrate scope and high yields. The synthetic utility of this method has been highlighted by a series of product derivatizations, and the potential of this transformation has been extended to synthesize TRPV1 antagonist and the key intermediate in the total synthesis of quebrachamine. Density functional theory(DFT) studies unveiled that the specific catalytic pocket assumed a significant role in the selective formation of cyano-substituted quaternary carbon centers.

关键词： chain-walking regioselectivity remote cyanation quaternary carbon centers unconjugated dienes

Dendritic tip selection during solidification of alloys: Insights from phase-field simulations

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CHINESE PHYSICS B 2024年第9期33卷 467-472页

作者： Zhang, Qingjie xing, Hui Wang, Lingjie Zhai, Wei Northwestern Polytech Univ Sch Phys Sci & Technol Xian 710072 Peoples R China Northwestern Polytech Univ Shenzhen Res & Dev Inst Shenzhen 518063 Peoples R China

The effect of undercooling Delta T and the interface energy anisotropy parameter epsilon(4 )on the shape of the equiaxed dendritic tip has been investigated by using a quantitative phase-field model for solidification of binary alloys. It was found that the tip radius rho increases and the tip shape amplitude coefficient A(4) decreases with the increase of the fitting range for all cases. The dendrite tip shape selection parameter sigma* decreases and then stabilizes with the increase of the fitting range, and sigma* increases with the increase of epsilon(4). The relationship between sigma* and epsilon(4) follows a power-law function sigma(& lowast; )proportional to epsilon(alpha)(4) , and alpha is independent of Delta T but dependent on the fitting range. Numerical results demonstrate that the predicted sigma* is consistent with the curve of microscopic solvability theory (MST) for epsilon(4) < 0.02, and sigma* obtained from our phase-field simulations is sensitive to the undercooling when epsilon(4) is fixed.

关键词： phase-field simulations dendritic structure interface energy anisotropy tip shape selection parameter GROWTH

DNA methylation in poultry:a review

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Journal of Animal Science and Biotechnology 2024年第2期15卷 509-518页

作者： xing Ju Zhijun Wang Danfeng Cai Semiu Folaniyi Bello Qinghua Nie State Key Laboratory for Conservation and Utilization of Subtropical Agro‑Bioresources Lingnan Guangdong Laboratory of AgricultureCollege of Animal ScienceSouth China Agricultural UniversityGuangzhouGuangdong 510642China Guangdong Provincial Key Lab of Agro‑Animal Genomics and Molecular Breeding and Key Lab of Chicken Genetics Breeding and ReproductionMinistry of AgricultureGuangzhouGuangdong 510642China College of Animal Science and Technology Zhejiang Agriculture and Forestry University666 Wusu RoadLin’an 311300China

As an important epigenetic modification,DNA methylation is involved in many biological processes such as animal cell differentiation,embryonic development,genomic imprinting and sex chromosome *** DNA methylation sequencing becomes more sophisticated,it becomes possible to use it to solve more zoological *** paper reviews the characteristics of DNA methylation,with emphasis on the research and application of DNA methylation in poultry.

关键词： CpG islands Differentially methylated genes Differentially methylated regions DNA methylation Poultry

Highly Differentiated Target Detection under Extremely Low-Light Conditions Based on Improved YOLOX Model

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1507-1537页

作者： Haijian Shao Suqin Lei Chenxu Yan xing Deng Yunsong Qi School of Computer Jiangsu University of Science and TechnologyZhenjiang212003China Department of Electrical and Computer Engineering University of NevadaLas VegasNV89154USA Zhejiang Geely Automobile Research Institute Ningbo315336China

This paper expounds upon a novel target detection methodology distinguished by its elevated discriminatory efficacy,specifically tailored for environments characterized by markedly low luminance *** methodologies struggle with the challenges posed by luminosity fluctuations,especially in settings characterized by diminished radiance,further exacerbated by the utilization of suboptimal imaging *** envisioned approach mandates a departure from the conventional YOLOX model,which exhibits inadequacies in mitigating these *** enhance the efficacy of this approach in low-light conditions,the dehazing algorithm undergoes refinement,effecting a discerning regulation of the transmission rate at the pixel level,reducing it to values below 0.5,thereby resulting in an augmentation of image ***,the coiflet wavelet transform is employed to discern and isolate high-discriminatory attributes by dismantling low-frequency image attributes and extracting high-frequency attributes across divergent *** utilization of CycleGAN serves to elevate the features of low-light imagery across an array of stylistic *** computational methodologies are then employed to amalgamate and conflate intricate attributes originating from images characterized by distinct stylistic orientations,thereby augmenting the model’s erudition *** validation conducted on the PASCAL VOC and MS COCO 2017 datasets substantiates pronounced *** refined low-light enhancement algorithm yields a discernible 5.9%augmentation in the target detection evaluation index when compared to the original *** Average Precision(mAP)undergoes enhancements of 9.45%and 0.052%in low-light visual renditions relative to conventional YOLOX *** envisaged approach presents a myriad of advantages over prevailing benchmark methodologies in the realm of target detection within environments marked by an acute scarcity of lumi

关键词： Target detection extremely low-light wavelet transformation highly differentiated features YOLOX

Runout prediction of potential landslides based on the multi-source data collaboration analysis on historical cases

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China Geology 2024年第2期7卷 264-276页

作者： Jun Sun Yu Zhuang Ai-guo xing Guizhou Geology and Mineral Engineering Construction Co. LtdGuiyang 550000China State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China

Long runout landslides involve a massive amount of energy and can be extremely hazardous owing to their long movement distance,high mobility and strong destructive *** methods have been widely used to predict the landslide runout but a fundamental problem remained is how to determine the reliable numerical *** study proposes a framework to predict the runout of potential landslides through multi-source data collaboration and numerical analysis of historical landslide ***,for the historical landslide cases,the landslide-induced seismic signal,geophysical surveys,and possible in-situ drone/phone videos(multi-source data collaboration)can validate the numerical results in terms of landslide dynamics and deposit features and help calibrate the numerical(rheological)***,the calibrated numerical parameters can be used to numerically predict the runout of potential landslides in the region with a similar geological setting to the recorded *** of the runout prediction approach to the 2020 Jiashanying landslide in Guizhou,China gives reasonable results in comparison to the field *** numerical parameters are determined from the multi-source data collaboration analysis of a historical case in the region(2019 Shuicheng landslide).The proposed framework for landslide runout prediction can be of great utility for landslide risk assessment and disaster reduction in mountainous regions worldwide.

关键词： Landslide runout prediction Drone survey Multi-source data collaboration DAN3D numerical modeling Jianshanying landslide Guizhou Province Geological hazards survey engineering

Numerical and experimental study on the falling film flow characteristics with the effect of co-current gas flow in hydrogen liquefaction process

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Petroleum Science 2024年第2期21卷 1369-1384页

作者： Chong-Zheng Sun Yu-xing Li Hui Han Xiao-Yi Geng Xiao Lu College of Energy Storage Technology Shandong University of Science and TechnologyQingdao 266590ShandongChina College of Pipeline and Civil Engineering/Shandong Provincial Key Laboratory of Oil&Gas Storage and Transportation Safety China University of PetroleumQingdao 266580ShandongChina

Liquid hydrogen storage and transportation is an effective method for large-scale transportation and utilization of hydrogen energy. Revealing the flow mechanism of cryogenic working fluid is the key to optimize heat exchanger structure and hydrogen liquefaction process(LH2). The methods of cryogenic visualization experiment, theoretical analysis and numerical simulation are conducted to study the falling film flow characteristics with the effect of co-current gas flow in LH2spiral wound heat *** results show that the flow rate of mixed refrigerant has a great influence on liquid film spreading process, falling film flow pattern and heat transfer performance. The liquid film of LH2mixed refrigerant with column flow pattern can not uniformly and completely cover the tube wall surface. As liquid flow rate increases, the falling film flow pattern evolves into sheet-column flow and sheet flow, and liquid film completely covers the surface of tube wall. With the increase of shear effect of gas-phase mixed refrigerant in the same direction, the liquid film gradually becomes unstable, and the flow pattern eventually evolves into a mist flow.

关键词： Hydrogen liquefaction Spiral wound heat exchanger Flow pattern transition Falling film flow

Determining beam transverse absolute position by triangulation of multi-electrode signal phase differences

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Nuclear Science and Techniques 2024年第8期35卷 38-47页

作者： xing Yang Hong‑Shuang Wang Yi‑Mei Zhou Yong‑Bin Leng Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201204China University of Science and Technology of China Hefei 230026China

Accurate measurement of the transverse position of a beam is crucial in particle accelerators because it plays a key role in determining the beam *** methods for beam-position measurement rely on the detection of image currents induced on electrodes or narrow-band wake field induced by a beam passing through a cavity-type ***,these methods have *** indirect measurement of multiple parameters is computationally complex,requiring external calibration to determine the system parameters in ***,the utilization of the beam signal information is ***,this study proposes a novel method for measuring the absolute electron beam transverse *** utilizing the geometric relationship between the center position of the measured electron beam and multiple detection electrodes and by analyzing the differences in the arrival times of the beam signals detected by these electrodes,the absolute transverse position of the electron beam crossing the electrode plane can be *** method features absolute position measurement,a position sensitivity coefficient independent of vacuum chamber apertures,and no requirement for a symmetrical detector electrode *** feasibility of this method is validated through numerical simulations and beam experiments.

关键词： Electron beam bunch-by bunch diagnostics Bunch position measurement Triangulation method Bunch phase Bunch-by-bunch Transverse position Pickup signal

Effect of low-speed waterjet pressure on the rock-breaking performance of unsubmerged cavitating abrasive waterjet

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Petroleum Science 2024年第4期21卷 2638-2649页

作者： Chen-xing Fan Deng Li Yong Kang Hai-Tao Zhang Hubei Key Laboratory of Waterjet Theory and New Technology Wuhan University School of Power and Mechanical Engineering Wuhan University

Unsubmerged cavitating abrasive waterjet(UCAWJ) has been shown to artificially create a submerged environment that produces shear cavitation, which effectively enhances rock-breaking performance. The shear cavitation generation and collapse intensity depend on the pressure difference between the intermediate high-speed abrasive waterjet and the coaxial low-speed waterjet. However, the effect of the pressure of the coaxial low-speed waterjet is pending. For this purpose, the effect of low-speed waterjet pressure on rock-breaking performance at different standoff distances was experimentally investigated,and the effects of erosion time and ruby nozzle diameter on erosion performance were discussed. Finally,the micromorphology of the sandstone was observed at different locations. The results show that increased erosion time and ruby nozzle diameter can significantly improve the rock-breaking performance. At different standoff distances, the mass loss increases first and then decreases with the increase of low-speed waterjet pressure, the maximum mass loss is 10.4 g at a low-speed waterjet pressure of0.09 MPa. The surface morphology of cavitation erosion was measured using a 3D profiler, the increase in both erosion depth and surface roughness indicated a significant increase in the intensity of the shear cavitation collapse. At a low-speed waterjet pressure of 0.18 MPa, the cavitation erosion surface depth can reach 600 μm with a roughness of 127 μm.

关键词： Rock-breaking Coaxial low-speed waterjet pressure Abrasive waterjet Cavitation Unsubmerged environment

26-electrons redox-active polyoxovanadate clusters for aqueous zincion batteries

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Nano Research 2024年第5期17卷 4047-4054页

作者： Yimin xing Wen Yan Haiyang Wu Peng Huang Chao Wang Chao Lai School of Chemistry and Materials Science Jiangsu Normal UniversityXuzhou 221116China

Aqueous zinc-ion batteries(ZIBs)are attaining increasing attention for their high safety and low *** significant progresses in realizing high-performance cathode material for ZIBs,simultaneously endowing them with high capacity and fast-charging capability,the long-term cycling stability remains a major unsolved *** this work,a polyoxovanadate cluster of(NH_(4))_(8)[V_(19)O_(41)(OH)_(9)]·11H_(2)O(NOV)is defined as a cathode material for ZIBs that contains mixed-valence vanadium sites(V^(4+)and V^(5+)).A maximum of 26 electrons can be accommodated in one[V_(19)O_(41)(OH)_(9)]^(8-){V_(19)O_(50)}cluster,contributing to the high theoretical specific capacity of 328 mA·h·g^(-1).The Ti_(3)C_(2)T_(x) MXene nanosheets are incorporated into NOV with the help of ionic liquid(IL)linkers to restrain the dissolution of vanadium species and facilitate electron transport across the *** interfacial bonding,anion exchange,and electrostatic interactions among NOV and MXene are provided by IL *** nanohybrid of NOV-IL-MXene endows excellent contact between MXene and NOV,thereby enhanced charge transfer is observed at ***,the as-synthesized NOV-IL-MXene cathodes exhibit high discharge capacity of 413 mA·h·g^(-1) at 0.2 A·g^(-1) even at high mass loading of 5.2 mg·cm^(-2),remarkable rate performance of 182 mA·h·g^(-1) at 10 A·g^(-1),and impressive cycling stability of 94%capacity retention after 2000 *** work opens up new opportunities to develop advanced polyoxovanadate hybrid cathodes for low-cost and high-performance aqueous ZIBs.

关键词： polyoxovanadate MXene composite materials cathodes zinc-ion batteries