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ORGANIC CHEMISTRY FRONTIERS 2022年第23期9卷 6592-6597页

作者： Luo, Zhengli chen, xuwen Xue, Jian Deng, Yaqi Dong, Suzhen Liu, Shunying East China Normal Univ Shanghai Engn Res Ctr Mol Therapeut & New Drug De Sch Chem & Mol Engn Shanghai 200062 Peoples R China

A rapid and efficient method for the synthesis of benzosultams containing continuous quaternary carbons in a one pot fashion has been developed with moderate to excellent yields at room temperature under air. The resu... 详细信息

关键词： Room temperature

One-Pot Construction of β-Selective Quinolines with γ-Quaternary Carbon from Vinylquinolines with Active Ylides via Pd/Sc/Bronsted Acid Co-Catalysis

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ACS CATALYSIS 2023年第10期13卷 6509-6517页

作者： Song, Longlong Xiong, Lulu Ni, Dan chen, Weixiong Ji, Jian Xue, Jian chen, xuwen Wu, Xiang He, Xiao Liu, Shunying East China Normal Univ Shanghai Engn Res Ctr Mol Therapeut & New Drug Dev Sch Chem & Mol Engn Shanghai 200062 Peoples R China New York Univ Shanghai New York Univ East China Normal Univ Ctr Computat Shanghai 200062 Peoples R China

Vinyl-substituted N-heterocycles, as more challenginginert olefinswith more stable reactivity, have brought about widespread attentionin the reaction of aza-Michael addition or reduction coupling ***, we report a [Pd-(eta(3)-C3H5)-Cl](2)/Sc-(OTf)(3)-catalyzed catalytic processaccelerated by Bronsted acids with a beta-selective aza-Michaeladdition to yield a gamma-quaternary carbon from vinyl-substitutedquinolines, diazos, and anilines/alcohols in one pot. The generationof anhydride analogues from Bronsted acid and the counter anion(OTf-) of Lewis acid promotes the activation ofthe corresponding Lewis acid and the nearly quantitative *** pi-cation and coordination interactions play pivotal rolesin the activation of the vinyl-quinoline substrates by the activatedLewis acid Sc-(OTf)(3). The control mechanistic evidence andDFT calculations presented a Pd/Sc/Bronsted acid co-catalyzedaddition mechanism. The triple co-catalytic system provides a strategyfor the activation of vinyl-quinolines with a linear selectivity containing gamma-quaternary carbon, and the developed method shows a broadsubstrate scope varying from alkyl/aryl alcohols and amines whichprovides a general and rapid strategy for the quinoline-based diverselibrary construction.

关键词： Pd Sc co-catalysis one-pot reaction vinylquinolines active ylide quaternary carbon

A Wide Range and High Repeatability MEMS Pressure Sensor Based on Graphene

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IEEE SENSORS JOURNAL 2022年第18期22卷 17737-17745页

作者： Zhu, Zehua Wang, Junqiang Wu, chenyang chen, xuwen Liu, Xiaofei Li, Mengwei North Univ China Natl Key Lab Instrumentat Sci & Dynam Measurement Taiyuan 030051 Peoples R China North Univ China Acad Adv Interdisciplinary Res Taiyuan 030051 Peoples R China

Graphene pressure sensors have attracted extensive attention due to their excellent performance. However, the range and linearity of conventional suspension graphene pressure sensors are too small to meet commercial requirements. In this article, we propose a wide range and high repeatability MEMS pressure sensor based on graphene array structure. Single-layer chemical vapor deposition (CVD) graphene was transferred at the root of silicon pressure-bearing elastic diaphragm, and it was simultaneously protected by the Si3N4 nanofilm. In addition, the Au/Sn eutectic bonding technology was employed to complete the hermetic package of the sensor. Pressure tests showed that the repeatability error of the pressure sensor in the range of 0-20 MPa was 4.062% full scale output (FSO) and the hysteresis was 2.118% FSO. Furthermore, the temperature resistance studies confirmed that the Si3N4 nanofilm can effectively protect graphene due to its extremely high thermal stability. And with excellent characteristics of high long-term stability, it can work stably in humid environments. Conclusionally, this research provides significant exploration to promote the practicality and commercialization of graphene devices.

关键词： Graphene high repeatability MEMS pressure sensors wide range

Simulating Thin Shells by Bicubic Hermite Elements

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COMPUTER-AIDED DESIGN 2024年 174卷

作者： Ni, Xingyu chen, xuwen Yu, cheng Wang, Bin chen, Baoquan Peking Univ Sch CS Beijing Peoples R China Peking Univ Sch IST Beijing Peoples R China Peking Univ Sch EECS Beijing Peoples R China Peking Univ State Key Lab Gen Artificial Intelligence Beijing Peoples R China Beijing Inst Gen Artificial Intelligence BIGAI State Key Lab Gen Artificial Intelligence Beijing Peoples R China

In this study, we present the bicubic Hermite element method (BHEM), a new computational framework devised for the elastodynamic simulation of thin-shell structures. The BHEM is constructed based on quadrilateral Hermite patches, which serve as a unified representation for shell geometry, simulation, collision avoidance, as well as rendering. Compared with the commonly utilized linear FEM, the BHEM offers higher-order solution spaces, enabling the capture of more intricate and smoother geometries while employing significantly fewer finite elements. In comparison to other high-order methods, the BHEM achieves conforming C 1 continuity for Kirchhoff-Love (KL) shells with minimal complexity. Furthermore, by leveraging the subdivision and convex hull properties of Hermite patches, we develop an efficient algorithm for ray-patch intersections, facilitating collision handling in simulations and ray tracing in rendering. This eliminates the need for laborious remodeling of the pre-existing surface as the conventional approaches do. We substantiate our claims with comprehensive experiments, which demonstrate the high accuracy and versatility of the proposed method.

关键词： Thin-shell simulation High-order finite elements Hermite interpolation

l2-DECOUPLING AND THE UNCONDITIONAL UNIQUENESS FOR THE BOLTZMANN EQUATION

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arXiv 2025年

作者： chen, xuwen Shen, Shunlin Zhang, Zhifei Department of Mathematics University of Rochester RochesterNY14627 United States School of Mathematical Sciences University of Science and Technology of China Hefei230026 China School of Mathematical Sciences Peking University Beijing100871 China

We broaden the application of the l2-decoupling theorem to the Boltzmann equation. We prove full-range Strichartz estimates for the linear problem in the Td setting. We establish space-time bilinear estimates, and hence the unconditional uniqueness of solutions to the Rd and Td Boltzmann equation for the Maxwellian particle and soft potential with an angular cutoff, adopting a unified hierarchy scheme originally developed for the nonlinear Schrödinger equation. Copyright © 2025, The Authors. All rights reserved.

关键词： Boltzmann equation

A Novel Radius Measurement Method for Vertical Oil Tank Based on Laser Tracking and Wall-Climbing Robot 16th

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A Novel Radius Measurement Method for Vertical Oil Tank Base...

16th International Conference on Intelligent Robotics and Applications, ICIRA 2023

作者： Zu, Hongfei Ma, Junjun Li, Cunjun chen, Xianlei Shi, Haolei chen, xuwen Zhang, Xiang chen, Zhangwei School of Mechanical Engineering Zhejiang Sci-Tech University Hangzhou310018 China Zhoushan Institute of Calibration and Testing for Qualitative and Technical Supervision Zhoushan316012 China Zhejiang Premax Co. Ltd. Ningbo315048 China State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang University Hangzhou310058 China

ISBN: (纸本)9789819965007

In order to address the issue of low efficiency and poor accuracy in measuring the radius of large vertical oil tanks, a novel measurement method based on the combination of laser tracking and wall-climbing robot was proposed in this manuscript. To solve the problem of light interruption during the laser tracking measurement process, an active spherically mounted retroreflector (SMR) device that can automatically align the laser was designed. A wall-climbing robot equipped with the active target and temperature sensor was developed to crawl on the tank wall and collect four-dimensional point cloud data. And a self-written program based on the PCL point cloud processing library was adopted to fit and calculate the tank plate radius. Furthermore, multiple measurements were carried out on a vertical oil tank with a capacity of 1000 m3, and the average radius error was only 1.39 mm, which strongly verified the repeatability and feasibility of the method proposed in this manuscript. This method provides a more effective and accurate method for measuring the radius of oil tanks, and it is foreseeable that it will be a good supplement to existing methods. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.

关键词： Oil tanks

THE DERIVATION OF THE BOLTZMANN EQUATION FROM QUANTUM MANY-BODY DYNAMICS

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arXiv 2023年

作者： chen, xuwen Holmer, Justin Department of Mathematics University of Rochester RochesterNY14627 United States Department of Mathematics Brown University 151 Thayer Street ProvidenceRI02912 United States

We consider the quantum many-body dynamics at the weak-coupling scaling. We derive rigorously the quantum Boltzmann equation, which contains the classical hard sphere model and, effectively, the inverse power law model, from the many-body dynamics assuming a physical and optimal regularity bound. The regularity bound we find, on the one hand, is satisfied by quasi-free solutions and comes from calculations regarding the local Maxwellian solution, in which we also prove that 2-body molecular chaos never happens unless N = +∞;on the other hand, it arises from the well-posedness threshold of the limiting Boltzmann equation below which we prove ill-posedness. That is, the regularity cannot be higher at the N-body level, cannot be lower in the limit, and is hence a double criticality. To work with this borderline case, we analyze all four sides, with respect to the Fourier transform, of the BBGKY hierarchy sequence with new tools and techniques. We prove well-definedness, compactness, convergence, and uniqueness of hierarchies right at the criticality to complete an optimal derivation. In particular, we have proved that, for physical N-particle solutions, the Boltzmann equation emerges as the mean-field limit and time is hence irreversible, from first principles of quantum *** Codes Primary 35Q20, 76P05, 81Q05, 81T27, 81V70, Secondary 35A01, 35C05, 35R25, 82C40 Copyright © 2023, The Authors. All rights reserved.

关键词： Boltzmann equation

Base-Induced Highly Regioselective Synthesis of N²-Substituted 1,2,3-Triazoles under Mild Conditions in Air

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ORGANIC LETTERS 2022年第1期24卷 132-136页

作者： Ji, Jian Guan, Cong Wei, Qinghua chen, xuwen Zhao, Yun Liu, Shunying East China Normal Univ Shanghai Engn Res Ctr Mol Therapeut & New Drug De Sch Chem & Mol Engn Shanghai 200062 Peoples R China

We developed a highly regioselective base-induced synthesis of N-2-substituted 1,2,3-triazoles from N-sulfonyl-1,2,3-triazoles and alkyl bromides/alkyl iodides at room temperature. We propose an S(N)2-like mechanistic pathway to explain the high N-2-regioselectivity. The protocol features a broad substrate scope and generates products in good to excellent yields (72-90%).

关键词： Triazole Anions Solvents Alkyls Selectivity

THE SECOND ORDER 2D BEHAVIORS OF A 3D BOSE GASES IN THE GROSS-PITAEVSKII REGIME

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arXiv 2024年

作者： chen, xuwen Wu, Jiahao Zhang, Zhifei Department of Mathematics University of Rochester RochesterNY14627 United States School of Mathematical Sciences Peking University Beijing100871 China

We consider a system of N bosons interacting in a three-dimensional box endowed with periodic boundary condition that is strongly confined in one direction such that the normalized thickness of the box d 1. We assume particles to interact through a repulsive, radially symmetric and short-range interaction potential with scattering length scale a d. We present a comprehensive study of such system in the Gross-Pitaevskii regime, up to the second order ground state energy, starting from proving optimal Bose-Einstein condensation results which were not previously available. The fine interplay between the parameters N, a and d generates three regions. Our result in one region on the one hand, is compatible with the classical three-dimensional Lee-Huang-Yang formula. On the other hand, it reveals a new mechanism exhibiting how the second order correction compensates and modifies the first order energy, which was previously thought of as containing a jump, and thus explains how a three-dimensional Bose gas system smoothly transits into two-dimensional system. Moreover, delving into the analysis of this new mechanism exclusive to the second order, we discover a dimensional coupling correlation effect, deeply buried away from the expected 3D and quasi-2D renormalizations, and calculate a new second order correction to the ground state energy. Copyright © 2024, The Authors. All rights reserved.

关键词： Bose-Einstein condensation

THE SECOND ORDER HUANG-YANG FORMULA TO THE 3D FERMI GAS: THE GROSS-PITAEVSKII REGIME

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arXiv 2024年

作者： chen, xuwen Wu, Jiahao Zhang, Zhifei Department of Mathematics University of Rochester RochesterNY14627 United States School of Mathematical Sciences Peking University Beijing100871 China

For a system of N Fermions of spin 1/2, with its interaction potential of scattering length a, the classical Huang-Yang formula [29] states that the energy density e(ρ) is of the form e(ρ) = 3/5 (3π2) 2/3 ρ 3/5 + 2πaρ2 + 12/35 (11 − 2 ln 2)3 1/3 π 2/3 a2ρ 7/3 + o(ρ 3). 7 We consider a general system of N Fermions of spin 1/q with the scattering length of the interaction potential at the scale a ∝ N−1, that is, in the Gross-Pitaevskii regime. We prove the 2nd order ground state energy approximation corresponding to the Huang-Yang formula. The thermodynamic limit case shares a similar logic, and could be dealt with in a separate paper. Copyright © 2024, The Authors. All rights reserved.

关键词： Fermions