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Chiral phosphoramidite ligand-modulated palladium auto-tandem catalysis for asymmetric dehydrogenative dienylation of imines with α-alkenes

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Science China Chemistry 2025年

作者： Zhong-sheng Nong Hao-fan Qian Ying-Chun Chen Pu-sheng Wang Liu-Zhu Gong Hefei National Research Center for Physical Sciences at the Microscale and Department of Chemistry University of Science and Technology of China Key Laboratory of Drug Targeting and Drug Delivery System (Sichuan University) Ministry of Education and Sichuan Research Center for Drug Precision Industrial Technology West China School of Pharmacy Sichuan University School of Materials and Chemistry Southwest University of Science and Technology

The development of efficient processes allowing rapid access to complex chiral molecules from easily available alkenes is a long-term pursuit in the synthetic chemistry community. Transition metal-catalyzed asymmetric functionalization of allylic C–H bond represents a unique alternative toward this goal. However, enantioselective dehydrogenative transformation of olefins to value-added optically enriched molecules remains yet to be discovered. Here, we report a highly enantioselective dehydrogenative dienylation of imines with unactivated α-alkenes driven by the synergistic action of palladium complex and carboxylic acid. Chiral phosphoramidite ligands turned out to be superior in modulating the performance of palladium autotandem catalysis and allowed a broad range of α-alkenes and imines to be transformed into chiral dienylamines. Mechanistic studies suggest that the dienes could be in situ generated from α-alkenes through a palladium(0)-mediated dehydrogenative process in the presence of excess benzoquinone oxidants, and then participated in the Pd-chiral phosphoramidite-catalyzed intermolecular vinylogous-type addition to the imines activated by the carboxylic acid co-catalyst. Notably, the second β-H elimination occurring in the dienylation event might be the turnover-limiting step.

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L^(p)Solution of Reflected BSDEs with One Continuous Barrier and Quasi-linear Growth Generators

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Acta Mathematicae Applicatae Sinica 2024年第4期40卷 943-953页

作者： sheng-jun fan School of Mathematics China University of Mining and TechnologyXuzhou 221116China

This paper is devoted to solving a reflected backward stochastic differential equation(BSDE in short)with one continuous barrier and a quasi-linear growth generator g,which has a linear growth in(y,z),except the upper direction in case of y1)solutions for the reflected *** also prove that the minimal Lpsolution can be approximated by a sequence of Lpsolutions of certain reflected BSDEs with Lipschitz generators.

关键词： Reflected BSDEs Quasi-linear growth L^(p)solution Existence Comparison theorem

Test on Stochastic Block Model:Local Smoothing and Extreme Value Theory

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Journal of Systems Science & Complexity 2022年第4期35卷 1535-1556页

作者： WU fan kong Xinbing XU Chao School of Mathematics Southeast UniversityNanjing211819China School of Statistics and Mathematics Nanjing Audit UniversityNanjing211815China School of Information Engineering Nanjing Audit UniversityNanjing211815China

In this paper,to obtain a consistent estimator of the number of communities,the authors present a new sequential testing procedure,based on the locally smoothed adjacency matrix and the extreme value *** the null hypothesis,the test statistic converges to the type I extreme value distribution,and otherwise,it explodes fast and the divergence rate could even reach n in the strong signal case where n is the size of the network,guaranteeing high detection *** method is simple to use and serves as an alternative approach to the novel one in Lei(2016)using random matrix *** detect the change of the community structure,the authors also propose a two-sample test for the stochastic block model with two observed adjacency *** studies justify the *** authors apply the proposed method to the political blog data set and find reasonable group structures.

关键词： Extreme value distribution network data stochastic block model

Adaptive algorithm for estimating excavation-Induced displacements using field performance data

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Underground Space 2020年第2期5卷 115-124页

作者： Haijian fan Gangqiang kong Transportation Engineer Texas Department of TransportationUSA College of Civil and Transportation Engineering Hohai UniversityNanjingJiangsu ProvinceChina

Empirical models provide a practical way to estimate the displacements induced by ***,there are uncertainties associated with the predictions of empirical models owing to:(a)the imperfect knowledge of the model and(b)the uncertainties of the input *** uncertainties of these models can be characterized by a bias factor which is defined as the ratio of the actual displacement to the predicted *** bias factors associated with the C&O method and the KJHH model are evaluated using the Bayesian method and a database of 71 excavations in *** improve the predictions of the maximum displacement,an adaptive algorithm is proposed using field performance *** performance of the proposed algorithm is demonstrated by an example in which excavation-induced displacements are generated by finite element method in normally consolidated *** example shows that the developed algorithm can significantly improve the predictions by incorporating the field performance data.

关键词： Excavation Displacement prediction Bayesian updating Model bias

Analysis of relative error in detection caused by signal-induced noise in Na lidar system

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Science China Earth Sciences 2018年第1期61卷 109-118页

作者： ZHANG YunPeng YI fan kong Wei School of Electronic Information Wuhan University

Signal-induced noise(SIN) in a photomultiplier tube(PMT) introduces bias into the Na density results that are retrieved from the backscattered signals of Na resonance fluorescence lidar systems. The response characteristics of a PMT when stimulated by a series of light pulses with a fixed width of 1 μs are therefore used to develop a precise SIN model to estimate the relative error caused by SIN. Unless the strong signals that are returned from the lower atmosphere are excluded, the measured density results are always smaller than the actual values, and the resulting relative error may be 50% or more. Three potential solutions to reduce the SIN were quantified for comparison, including use of a chopper system, use of a gated circuit, and separation of the laser beam and the telescope receiver. When optimized parameters are used for these technologies, the relative error can then be reduced to less than 2%.

关键词： Lidar Signal-induced noise Photomultiplier tube

Existence, Uniqueness and Approximation for Lp Solutions of Reflected BSDEs with Generators of One-sided Osgood Type

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Acta Mathematica Sinica,English Series 2017年第6期33卷 807-838页

作者： sheng Jun fan School of Mathematics China University of Mining and Technology Xuzhou 221116 P. R. China

We prove several existence and uniqueness results for Lp （p 〉 1） solutions of reflected BSDEs with continuous barriers and generators satisfying a one-sided Osgood condition together with a general growth condition in y and a uniform continuity condition or a linear growth condition in z. A necessary and sufficient condition with respect to the growth of barrier is also explored to ensure the existence of a solution. And, we show that the solutions may be approximated by the penalization method and by some sequences of solutions of reflected BSDEs. These results are obtained due to the development of those existing ideas and methods together with the application of new ideas and techniques, and they unify and improve some known works.

关键词： Reflected backward stochastic differential equation Lp solutions comparison theorem,one-sided Osgood condition uniform continuity condition

Properties of Solutions of BSDEs with Integrable Parameters

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Acta Mathematicae Applicatae Sinica 2007年第4期23卷 697-704页

作者： sheng-jun fan College of Sciences China University of Mining & Technology Xuzhou 221008 China

The main result of this study is to obtain, using the localization method in Briand et al. Levi, Fatou and Lebesgue type theorems for the solutions of certain one-dimensional backward stochastic differential equation ... 详细信息

关键词： Backward stochastic differential equation integrable parameters Lebesgue theorem

A Relationship Between the Conditional g-Evaluation System and the Generator g and Its Applications

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Acta Mathematica Sinica,English Series 2007年第8期23卷 1427-1434页

作者： sheng Jun fan College of Sciences China University of Mining and Technology Xuzhou 221008 P. R. China

In this paper, under the most elementary conditions on a backward stochastic differential equation （BSDE for short） introduced by Peng, a new relationship between the conditional g-evaluation system and the generator g of BSDE is obtained in the sense of ＂process＂, based on some recent results of Jiang. Moreover, as applications, two converse comparison theorems and two uniqueness theorems on the generators of BSDEs are proved.

关键词： backward stochastic differential equation g-evaluation g-expectation generator converse comparison theorem

Moment Inequality and Hlder Inequality for BSDEs

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Acta Mathematicae Applicatae Sinica 2009年第1期25卷 11-20页

作者： sheng-jun fan College of School China University of Mining and Technology Xuzhou 221008 China

Under the Lipschitz and square integrable assumptions on the generator g of BSDEs, this paper proves that if g is positively homogeneous in （y, z） and is decreasing in y, then the Moment inequality for BSDEs with generator g holds in general, and if g is positively homogeneous and sub-additive in （y, z）, then the HSlder inequality and Minkowski inequality for BSDEs with generator g hold in general.

关键词： Backward stochastic differential equation moment inequality for bsdes hSlder inequality forbsdes minkowski inequality for BSDEs