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An unprecedented synthesis of axially chiral biaryls by rearrangement and aromatization of carbocations with central-to-axial conversion of chirality

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Science China Chemistry 2024年第9期67卷 2998-3003页

作者： Qi liu Xue-Dong li liang Cheng li liu Beijing National Laboratory for Molecular Sciences(BNLMS) CAS Key Laboratory of Molecular Recognition and FunctionCAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The central-to-axial chirality conversion represents a fascinating class of chemical processes consisting of the destruction of stereogenic centers and the simultaneous installation of axial chiral elements,which provides efficient methods for the preparation of axially chiral ***,developing catalytic asymmetric approaches for constructing these central chirality precursors and the efficient central-to-axial chirality conversion remains a challenge due to the requirement of aromatization or elimination *** this work,we have developed an unprecedented enantioselective intramolecular FriedelCrafts alkylation with unactivated-ketone carbonyls from which a chiral tertiary alcohol was generated with high efficiency and excellent *** addition,the central-to-axial chirality conversion strategy has been successfully applied to the synthesis of enantioenriched biaryls via a less-explored carbocation-initiated rearrangement and aromatization under the promotion of Lewis *** methodology provided a straightforward and sustainable access to a broad range of biaryl-2-carboxylic acid and in excellent yields(up to 92%)and excellent central-to-axial chirality conversion(up to 99%conversion percentage).This work could be a great model for developing new methods for synthesizing axially chiral biaryls and a general protocol for the rearrangement and aromatization of carbocations for further functionalization.

关键词： br?nsted acid catalysis desymmetrization phosphoric acid axially chiral biaryls central-to-axial conversion

SimHOEPI:A resampling simulator for generating single nucleotide polymorphism data with a high-order epistasis model

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Quantitative Biology 2024年第2期12卷 197-204页

作者： Yahan li Xinrui Cai Junliang Shang Yuanyuan Zhang jin-Xing liu School of Computer Science Qufu Normal UniversityRizhaoChina School of Information and Control Engineering Qingdao University of TechnologyQingdaoChina School of Health and life Sciences University of Health and Rehabilitation SciencesQingdaoChina

Epistasis is a ubiquitous phenomenon in genetics,and is considered to be one of main factors in current efforts to unveil missing heritability of complex *** data is crucial for evaluating epistasis detection tools in genome-wide association studies(GWAS).Existing simulators normally suffer from two limitations:absence of support for high-order epistasis models containing multiple single nucleotide polymorphisms(SNPs),and inability to generate simulation SNP data *** this study,we proposed a simulator SimHOEPI,which is capable of calculating penetrance tables of high-order epistasis models depending on either prevalence or heritability,and uses a resampling strategy to generate simulation data *** of SimHOEPI are the preservation of realistic minor allele frequencies in sampling data,the accurate calculation and embedding of high-order epistasis models,and acceptable simulation time.A series of experiments were carried out to verify these properties from different *** results show that SimHOEPI can generate simulation SNP data independently with high-order epistasis models,implying that it might be an alternative simulator for GWAS.

关键词： high-order epistasis model penetrance table resampling strategy simulation single nucleotide polymorphisms

Dynamic Analysis of A Deepwater Drilling Riser with A New Hang-off System

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China Ocean Engineering 2024年第1期38卷 29-41页

作者： li Yan-wei liu Xiu-quan WANG jin-long CHEN Guo-ming CHANG Yuan-jiang SHENG Lei-xiang Centre for Offshore Engineering and Safety Technology China University of PetroleumQingdao 266580China National Engineering Laboratory of Offshore Geophysical and Exploration Equipment China University of PetroleumQingdao 266580China China CNOOC Research Institute Co. Ltd.Beijing 100028China

The safety of risers in hang-off states is a vital challenge in offshore oil and gas engineering.A new hang-off system installed on top of risers is proposed for improving the security of *** approach leads to a challenging problem:coupling the dynamics of risers with a new hang-off system combined with multiple structures and complex *** accurately analyze the dynamic responses of the coupled system,a coupled dynamic model is established based on the Euler-Bernoulli beam-column theory and penalty function method.A comprehensive analysis method is proposed for coupled dynamic analysis by combining the finite element method and the Newmarkβ*** analysis program is also developed in MATLAB for dynamic *** simulation results show that the dynamic performances of the risers at the top part are significantly improved by the new hang-off system,especially the novel design,which includes the centralizer and articulation *** bending moment and lateral deformation of the risers at the top part decrease,while the hang-off joint experiences a great bending moment at the bottom of the lateral restraint area which requires particular attention in design and *** platform navigation speed range under the safety limits of risers expands with the new hang-off system in use.

关键词： deepwater drilling riser new hang-off system dynamic analysis finite element method penalty function method

The clutch size,incubation behavior of Reeves’s Pheasant(Syrmaticus reevesii) and their responses to ambient temperature and precipitation

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Avian Research 2024年第1期15卷 72-80页

作者： Ting jin Shuai Lu Yunqi Wang Junqin Hua Zhengxiao liu Qian Hu Yating liu Yuze Zhao Jianqiang li Jiliang Xu School of Ecology and Nature Conservation Beijing Forestry UniversityBeijing100083China State Key Laboratory of Efficient Production of Forest Resources Beijing Forestry UniversityBeijing100083China

Weather conditions play a pivotal role in embryo development and parental incubation costs,potentially impacting the clutch size and incubation behavior of *** these effects is crucial for bird ***’ s Pheasant(Syrmaticus reevesii) is a threatened species endemic to China,which is characterized by female-only ***,there is a lack of information regarding the impact of weather conditions on clutch size and incubation behavior in this *** satellite tracking,we tracked 27 wild female Reeves’ s Pheasants from 2020 to 2023 in Hubei Province,*** explored their clutch size and incubation behavior,as well as their responses to ambient temperature and *** size averaged 7.75 ±1.36,had an association with average ambient temperature and average daily precipitation during the egglaying period,and was potentially linked to female breeding *** the incubation period,females took an average of 0.73 ±0.46 recesses every 24 h,with an average recess duration of 100.80 ±73.37 min and an average nest attendance of 92.98 ±5.27%.They showed a unimodal recess pattern in which nest departures peaked primarily between 13:00 and 16:***,females rarely left nests when daily precipitation was *** duration and nest attendance were influenced by the interaction between daily mean ambient temperature and daily precipitation,as well as day of ***,there was a positive correlation between clutch size and recess *** results contribute valuable insights into the lifehistory features of this endangered species.

关键词： Ambient temperature Clutch size Incubation behavior Precipitation Reeves’s Pheasant

Recent progress on nanomaterial-based electrochemical dissolved oxygen sensors

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Chinese Journal of Chemical Engineering 2024年第4期68卷 103-119页

作者： Shaoqi Zhang Tao liu Zhenyu Chu Wanqin jin State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 211816China

Dissolved oxygen(DO)usually refers to the amount of oxygen dissolved in *** the environment,medicine,and fermentation industries,the DO level needs to be accurate and capable of online monitoring to guide the precise control of water quality,clinical treatment,and microbial *** with other analytical methods,the electrochemical strategy is superior in its fast response,low cost,high sensitivity,and portable ***,an electrochemical DO sensor faces a trade-off between sensitivity and long-term stability,which strongly limits its practical *** solve this problem,various advanced nanomaterials have been proposed to promote detection performance owing to their excellent electrocatalysis,conductivity,and chemical ***,in this review,we focus on the recent progress of advanced nanomaterial-based electrochemical DO *** the comparison of the working principles on the main analysis techniques toward DO,the advantages of the electrochemical method are *** is placed on recently developed nanomaterials that exhibit special characteristics,including nanostructures and preparation routes,to benefit DO ***,we also introduce some interesting research on the configuration design of the electrode and device,which is rarely ***,the different requirements of the electrochemical DO sensors in different application fields are included to provide brief guidance on the selection of appropriate ***,the main challenges are evaluated to propose future development prospects and detection strategies for nanomaterial-based electrochemical sensors.

关键词： Nanomaterial Dissolved oxygen Electrochemical sensor Nanostructures Detection principles

Inhibiting shuttle effect of lithium polysulfides by double metal selenides for high-performance lithium-sulfur batteries

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Rare Metals 2024年第6期43卷 2546-2559页

作者： Lei li Xue-jing Yang Yi-Yang li Bo jin Hui liu Meng-Yang Cui Dong-Bo Guan Xing-You Lang Qing Jiang Key Laboratory of Automobile Materials Ministry of Educationand College of Materials Science and EngineeringJilin UniversityChangchun 130022China

lithium-sulfur batteries(LSBs)have attracted the attention of more and more researchers due to the advantages of high energy density,environmental friendliness,and low production ***,the low electronic conductivity of active material and shuttling effect of lithium polysulfides(liPSs)limit the commercial development of *** solve these problems,we design a core-shell composite with nitrogen-doped carbon(NC)and two types of selenides(FeSe_(2)-NC@ZnSe-NC).The FeSe_(2)-NC@ZnSe-NC has a strong adsorption capacity,and can effectively adsorb *** the same time,it also effectively alleviates the shuttling effect of liPSs,and improves the utilization of the active substance during the charge/discharge reaction *** mechanism involved in FeSe_(2)-NC@ZnSe-NC is demonstrated by both experiments and density-functional theory(DFT)*** electrochemical test results indicate that LSB with S/FeSe_(2)-NC@ZnSe-NC delivers an initial discharge capacity of 1260 mAh·g^(-1)at *** after 500 cycles at 1C,the capacity decay rate per cycle is 0.031%,and the capacity retention rate is 85%.The FeSe_(2)-NC@ZnSe-NC core-shell structure verifies a rational strategy to construct an electrode material for high-performance LSBs.

关键词： lithium-sulfur batteries Shuttling effect Metal selenide Nitrogen-doped carbon lithium polysulfides

Nonsingularity of grain-like cascade feedback shift registers subject to fault attacks

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Science China(Information Sciences) 2024年第9期67卷 184-195页

作者： Haitao li Zhaoqi liu Wenrong li School of Mathematics and Statistics Shandong Normal University

Feedback shift registers(FSRs) are pivotal in generating pseudorandom sequences for stream ciphers and play a crucial role in error detection and code correction. This paper investigates the resilience of grain-like cascade FSRs(GLC-FSRs) against two types of fault attacks: hard and soft. First, we introduce a new criterion for assessing the nonsingularity of GLC-FSRs using the structure matrices of feedback functions,which enable the measurement of the number of nonsingular GLC-FSRs. Second, we demonstrate that GLC-FSRs subject to hard fault attacks become singular as determined by this new criterion. Ultimately,by constructing a soft fault bit set, we discuss the resilience of GLC-FSRs to soft fault attacks. Results demonstrate that singular GLC-FSRs remain singular after being injected by soft fault attacks. Conversely,for nonsingular GLC-FSRs, suitable soft fault attacks are designed to maintain their nonsingular status.

关键词： grain-like cascade feedback shift register fault attack nonsingularity semi-tensor product

Recurrent Neural Network Inspired Finite-Time Control Design

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IEEE/CAA Journal of Automatica Sinica 2024年第6期11卷 1527-1529页

作者： Jianan liu Shihua li Rongjie liu School of Automation Southeast UniversityNanjing 210096China Department of Statistics Florida State UniversityFL 32304 USA IEEE

Dear Editor,This letter is concerned with the role of recurrent neural networks(RNNs)on the controller design for a class of nonlinear *** by the architectures of RNNs,the system states are stacked according to the dynamic along with time while the controller is represented as the neural network *** build the bridge between RNNs and finite-time controller,a novel activation function is imposed on RNNs to drive the convergence of states at finite-time and propel the overall control process *** stability proof is briefly provided for the convergence of the proposed finite-time *** last,a numerical simulation example is presented to illustrate the efficiency of the proposed *** networks can be classified as static(feedforward)and dynamic(recurrent)nets[1].The former nets do not perform well in dealing with training data and using any information of the local data structure[2].In contrast to the feedforward neural networks,RNNs are constituted by high dimensional hidden states with dynamics.

关键词： dynamics finite proof

Transient Monte Carlo simulation of phonon transport in silicon nanofilms with the local heat source

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Science China(Technological Sciences) 2024年第7期67卷 2087-2098页

作者： li JiaQi CAI JiuQing li Rui liu ZhiChun liu Wei School of Energy and Power Engineering Huazhong University of Science and TechnologyWuhan 430074China Wuhan Second Ship Design and Research Institute Wuhan 430205China

Accurate prediction of junction temperature is crucial for the efficient thermal design of silicon nano-devices. In nano-scale semiconductor devices, significant ballistic effects occur due to the mean free path of phonons comparable to the heat source size and device scale. We employ a three-dimensional non-gray Monte Carlo simulation to investigate the transient heat conduction of silicon nanofilms with both single and multiple heat sources. The accuracy of the present method is first verified in the ballistic and diffusion limits. When a single local heat source is present, the width of the heat source has a significant impact on heat conduction in the domain. Notably, there is a substantial temperature jump at the boundary when the heat source width is 10 *** increasing heat source width, the boundary temperature jump weakens. Furthermore, we observe that the temperature excitation rate is independent of the heat source width, while the temperature influence range expands simultaneously with the increase in heat source width. Around 500 ps, the temperature and heat flux distribution in the domain stabilize. In the case of dual heat sources, the hot zone is broader than that of a single heat source, and the temperature of the hot spot decreases as the heat source spacing increases. However, the mean heat flux remains unaffected. Upon reaching a spacing of 200 nm between the heat sources, the peak temperature in the domain remains unchanged once a steady state is reached. These findings hold significant implications for the thermal design of silicon nano-devices with local heat sources.

关键词： phonon transport Monte Carlo simulation transient heat conduction silicon nanofilms local heat source