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

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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Adaptive Control of a Chaotic System with Delay

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Chinese Physics Letters 1998年第7期15卷 477-479页

作者： tian yu-chu National Key Laboratory of Industrial Control Technology Institute of Industrial Process ControlZhejiang UniversityHangzhou 310027

A model-reference adaptive control strategy is proposed for a delay chaotic system with known or unknown *** analysis and numerical simulations show that the controlled system state can track an arbitrarily given refe... 详细信息

关键词： parameters chaotic system

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Silicone Elastomer with High Elongation at Break Used in Digital Light Processing 3D Printing

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Chinese Journal of Polymer Science 2023年第11期41卷 1786-1795,I0010页

作者： tian-Xin yu Ya-yuan Liu Fu-yue tian Nan-Ying Ning Bing yu Ming tian State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical TechnologyBeijing 100029China Key Laboratory of Carbon Fiber and Functional Polymers Ministry of EducationBeijing University of Chemical TechnologyBeijing 100029China

3D printing silicone elastomer has demonstrated great potential in diverse areas such as medical devices,flexible electronics and soft *** is of great value to investigate how to improve the mechanical properties,including tensile strength and elongation at break of printed *** this work,a light curing system that can be applied in silicone elastomer 3D printing is explored,which is composed of vinyl terminated polysiloxane as the macromer and thiol containing polysiloxane as the crosslinking agent,and a chain extension reaction is also introduced into this light curing system via the addition of the chain extender dithiol molecules,and a light curing system accompanied with chain extension is designed and realized based on the thiol-ene click reaction *** reinforced with silica fillers,the obtained light curing system can endow the light curing silicone elastomer with better mechanical properties under the condition of a lower viscosity of the precursor,the tensile strength and elongation at break can reach 525.5 k Pa and 601%,*** light curing system provides a feasible method to solve the contradiction between the viscosity of the precursor and the mechanical properties of the light curing elastomer in the digital light processing(DLP)3D printing field.

关键词： Silicone elastomer Thiol-ene click chemistry Light curing 3D-printing Chain extender

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Development of a compact DOI-TOF detector module for high-performance PET systems

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Nuclear Science and Techniques 2017年第4期28卷 1-7页

作者： Qing-Yang Wei tian-Peng Xu tian-tian Dai Shi Wang Ya-Qiang Liu yu Gu tian-yu Ma School of Automatic and Electrical Engineering University of Science and Technology Beijing Beijing 100083 China Department of Engineering Physics Tsinghua UniversityBeijing 100084 China Key Laboratory of Particle and Radiation Imaging (Tsinghua University) Ministry of Education Beijing 100084 China Department of Radiation Oncology China-Japan Friendship Hospital Beijing 100029 China

To increase spatial resolution and signal-to-noise ratio in PET imaging,we present in this paper the design and performance evaluation of a PET detector module combining both depth-of-interaction(DOI) and time-offlight(TOF) *** detector module consists of a staggered dual-layer LYSO block with2 mm × 2 mm × 7 mm ***-compatible SiPM sensors(MicroFJ-30035-TSV,SensL) are assembled into an 8× 8 *** signals from both fast and slow outputs are read out by a 128-channel ASIC *** test its performance,a flood histogram is acquired with a ^(22)Na point source on top of the detector,and the energy resolution and the coincidence resolving time(CRT) value for each individual crystal are *** flood histogram shows excellent crystal separation in both *** average energy resolution at 511 keV is 14.0 and 12.7%at the bottom and top layers,*** average CRT of a single crystal is 635 and 565 ps at the bottom and top layers,*** conclusion,the compact DOI-TOF PET detector module is of excellent crystal identification capability,good energy resolution and reasonable time resolution and has promising application prospective in clinical TOF PET,PET/MRI,and brain PET systems.

关键词： Positron emission tomography SiPM Depth of interaction (DOI) Time-of-flight (TOF)

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Prediction of ball-on-plate friction and wear by ANN with data-driven optimization

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Friction 2024年第6期12卷 1235-1249页

作者： Alexander KOVALEV yu tian Yonggang MENG State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China

For training artificial neural network(ANN),big data either generated by machine or measured from experiments are used as input to"learn"the unspecified functions defining the *** experimental data are fed directly into the optimizer allowing training to be performed according to a predefined loss *** predict sliding friction and wear at mixed lubrication conditions,in this study a specific ANN structure was so designed that deep learning algorithms and data-driven optimization models can be *** ball-on-plate friction and wear data were analyzed using the specific training procedure to optimize the weights and biases incorporated into the neural layers of the ANN,and only two independent experimental data sets were used during the ANN optimization *** the training procedure,the ANN is capable to predict the contact and hydrodynamic pressure by adapting the output data according to the tribological condition implemented in the optimization algorithm.

关键词： machine learning deep learning artificial neural network mixed lubrication

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Attitude Tracking Control for Rigid Spacecraft with Arbitrary Convergence Time

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Journal of Systems Science & Complexity 2024年第6期37卷 2579-2594页

作者： XU yu-tian WU Ai-Guo Guangdong Provincial Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robotics Harbin Institute of Technology(Shenzhen)Shenzhen 518055China Key University Laboratory of Mechanism&Machine Theory and Intelligent Unmanned Systems of Guangdong Harbin Institute of Technology(Shenzhen)Shenzhen 518055China Department of Automation Harbin Institute of Technology(Shenzhen)Shenzhen 518055China HIT Wuhu Robot Technology Research Institute Wuhu 241060China

In this paper,attitude tracking control with arbitrary convergence time for rigid spacecraft is ***,a novel time-varying sliding function is proposed to achieve free-will arbitrary time convergence when the system states reside on the sliding *** such a sliding function,an attitude tracking controller is designed to guarantee that the states of the closed-loop system converge to the sliding surface within a predetermined time in the presence of external *** free-will arbitrary time convergences of the closed-loop system and sliding function are illustrated by numerical simulations.

关键词： Attitude tracking free-will arbitrary time stability rigid spacecraft sliding mode control

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Subspace dual super wavelet and Gabor frames

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Science China Mathematics 2017年第12期60卷 2429-2446页

作者： tian yu LI yunZhang College of Applied Sciences Beijing University of Technology Beijing 100124 China

Due to its potential applications in multiplexing techniques, the study of superframes has interested some researchers. This paper addresses dual super wavelet and Gabor frames in the subspace setting. We obtain a basic-equation characterization for subspace dual super wavelet and Gabor frames. In addition, applying this characterization, we derive a procedure that allows for constructing subspace dual super wavelet frames based on certain subspace dual super Gabor frames, and vice versa. Our results are new even in L^2(R, CL) setting.

关键词： frame superframe dual super wavelet frame dual super Gabor frame

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Doubled conformal compactification

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Science China(Physics,Mechanics & Astronomy) 2014年第9期57卷 1630-1636页

作者： SUN ZhaoYong tian yu School of Physics University of Chinese Academy of Sciences State Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences

We use Weyl transformations between the Minkowski spacetime and dS/AdS spacetime to show that one cannot well define the electrodynamics globally on the ordinary conformal compactification of the Minkowski spacetime(or dS/AdS spacetime),where the electromagnetic field has a sign factor(and thus is discountinuous)at the light *** problem is intuitively and clearly shown by the Penrose diagrams,from which one may find the remedy without too much *** use the Minkowski and dS spacetimes together to cover the compactified space,which in fact leads to the doubled conformal *** this doubled conformal compactification,we obtain the globally well-defined electrodynamics.

关键词： conformal transformations electrodynamics doubled Penrose diagrams conformal compactification

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Non-spherical particle mixing behaviors by spherical inert particles assisted in a fluidized bed

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Petroleum Science 2020年第2期17卷 509-524页

作者： An-Xing Ren tian-yu Wang tian-Qi Tang yu-Rong He School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China Heilongjiang Key Laboratory of New Energy Storage Materials and Processes School of Energy Science and EngineeringHarbin Institute of TechnologyHarbin 150001China

Fluidized beds are widely used in many industrial fields such as petroleum,chemical and *** actual industrial processes,spherical inert particles are typically added to the fluidized bed to promote fluidization of non-spherical *** mixing behaviors of binary mixtures in a fluidized bed has specific significance for the design and optimization of related industrial *** this study,the computational fluid dynamic-discrete element method with the consideration of rolling friction was applied to evaluate the mixing behaviors of binary mixtures comprising spherocylindrical particles and spherical particles in a fluidized *** simulation results indicate that the differences between rotational particle velocities were higher than those of translational particle velocities for spherical and non-spherical particles when well ***,as the volume fraction of the spherocylindrical particles increases,translational and rotational granular temperatures gradually *** addition,the addition of the spherical particles makes the spherocylindrical particles preferably distributed in a vertical orientation.

关键词： Non-spherical particle Fluidized bed Discrete element method Binary mixtures

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Quantum Private Comparison via Cavity QED

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Communications in Theoretical Physics 2017年第2期67卷 147-156页

作者： tian-yu Ye College of Information and Electronic Engineering Zhejiang Gongshang University Hangzhou 310018 China

The first quantum private comparison(QPC) protocol via cavity quantum electrodynamics(QED) is proposed in this paper by making full use of the evolution law of atom via cavity QED, where the third party(TP) is allowed to misbehave on his own but cannot conspire with either of the two users. The proposed protocol adopts two-atom product states rather than entangled states as the initial quantum resource, and only needs single-atom measurements for two users. Both the unitary operations and the quantum entanglement swapping operation are not necessary for the proposed protocol. The proposed protocol can compare the equality of one bit from each user in each round comparison with one two-atom product state. The proposed protocol can resist both the outside attack and the participant ***, it can prevent TP from knowing two users' secrets. Furthermore, the qubit efficiency of the proposed protocol is as high as 50%.

关键词： quantum private comparison(QPC) third party(TP) cavity quantum electrodynamics(QED) product state participant attack

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