检索结果-南通市图书馆

Rhodium-Catalyzed N-Arylation Addition of Arylboronic Acids to Ketimines

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2024年第18期42卷 2243-2248页

作者： Xue-Wei qian Xing-Wen Sun Department of Chemistry Fudan University220 Handan RoadShanghai 200433China

Herein,we report rhodium catalyzed N-arylation via addition of arylboronic acids to electron-deficientα-iminoesters which can be prepared in high efficiency by using easily accessible B-carbonyl *** reaction is highly regiospecific to achieve the N-aryl addition efficiently with up to 99%yield under mild *** corresponding product can be further efficiently converted into indoles andaseries of other important building blocks.

关键词： Rhodium catalyzed N-Arylation addition Amines Umpolung Indole C-C coupling

Highly efficient photocatalytic conversion of CO_(2) into CH_(4) over Cu single atom promoted heterojunction:The effect of uplifted d-band center

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第2期35卷 484-488页

作者： Hao Zhang qian Liu Zhurui Shen School of Materials Science and Engineering Nankai UniversityTianjin 300350China

Photoreduction of CO_(2) to solar fuels has caused great interest,but suffers from low catalytic efficiency and poor ***,we designed a S-scheme heterojunction(Cu-TiO_(2)/WO_(3))with Cu single atom to significantly boost the photoreduction of CO_(2).Notably,the developed Cu-TiO_(2)/WO_(3) achieved the solardriven conversion of CO_(2) to CH_(4) with an evolution rate of 98.69μmol g^(−1. h^(−1.,and the electron selectivity of CH_(4) reached 88.5%.The yield was much higher than those of pristine WO_(3),TiO_(2)/WO_(3) and Cu-TiO_(2) *** and theoretical analysis suggested that the S-scheme heterojunction accelerated charge migration and inhibited the recombination of electron-hole ***,the charge separation effect of the heterojunction meliorated the position of the *** uplifted d-band centers of Cu and Ti on Cu-TiO_(2)/WO_(3) not only improved the electron interaction between Cu single atoms and substrate-TiO_(2),accelerated the adsorption and activation of CO_(2) on the active sites of Cu single atom,but also optimized the Gibbs free energies of CH 4 formation pathway,leading to excellent selectivity toward CH_(4).This work provides new insights into the design of photocatalyst systems with high photocatalytic performance.

关键词： Cu single atom Heterojunction CO_(2)photoreduction d-band center DFT

Derivatives of Intersection Local Time for Two Independent Symmetricα-stable Processes

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2024年第5期40卷 1273-1292页

作者： Huan ZHOU Guang Jun SHEN qian YU Department of Mathematics Anhui Normal UniversityWuhu 241002P.R.China Department of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 211106P.R.China Key Laboratory of Mathematical Modelling and High Performance Computing of Air Vehicles(NUAA) MIITNanjing 211106P.R.China

In this paper,we consider the derivatives of intersection local time for two independent d-dimensional symmetricα-stable processes X^(α) and X^(α)with respective indices α and α.We first study the sufficient condition for the existence of the derivatives,which makes us obtain the exponential integrability and H?lder *** we show that this condition is also necessary for the existence of derivatives of intersection local time at the ***,we also study the power variation of the derivatives.

关键词： Symmetric stable processes intersection local time exponential integrability power variation

Hierarchical vectorization for facial images

在线全文

学校读者我要写书评

暂无评论

Computational Visual Media 2024年第1期10卷 97-118页

作者： qian Fu Linlin Liu Fei Hou Ying He School of Computer Science and Engineering Nanyang Technological University639798SingaporeSingapore Data61 Commonwealth Scientific and Industrial Research OrganisationSydney2015Australia Interdisciplinary Graduate School Nanyang Technological University and Alibaba Group639798SingaporeSingapore State Key Laboratory of Computer Science Institute of SoftwareChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China

The explosive growth of social media means portrait editing and retouching are in high *** portraits are commonly captured and stored as raster images,editing raster images is non-trivial and requires the user to be highly *** at developing intuitive and easy-to-use portrait editing tools,we propose a novel vectorization method that can automatically convert raster images into a 3-tier hierarchical *** base layer consists of a set of sparse diffusion curves(DCs)which characterize salient geometric features and low-frequency colors,providing a means for semantic color transfer and facial expression *** middle level encodes specular highlights and shadows as large,editable Poisson regions(PRs)and allows the user to directly adjust illumination by tuning the strength and changing the shapes of *** top level contains two types of pixel-sized PRs for high-frequency residuals and fine details such as pimples and *** train a deep generative model that can produce high-frequency residuals *** to the inherent meaning in vector primitives,editing portraits becomes easy and *** particular,our method supports color transfer,facial expression editing,highlight and shadow editing,and automatic *** quantitatively evaluate the results,we extend the commonly used FLIP metric(which measures color and feature differences between two images)to consider *** new metric,illumination-sensitive FLIP,can effectively capture salient changes in color transfer results,and is more consistent with human perception than FLIP and other quality measures for portrait *** evaluate our method on the FFHQR dataset and show it to be effective for common portrait editing tasks,such as retouching,light editing,color transfer,and expression editing.

关键词： face editing vectorization Poisson editing color transfer illumination editing expression editing

Confinement of Fe atoms between MoS_(2) interlayers drives phase transition for improved reactivity in Fenton-like reactions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第3期17卷 1132-1139页

作者： Yibing Sun Yu Zhou Hongchao Li Chuan Wang Xuan Zhang qian Ma Yingchun Cheng Jieshu qian Bingcai Pan Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse School of Environmental and Biological EngineeringNanjing University of Science and TechnologyNanjing 210094China Key Laboratory of Flexible Electronics and Institute of Advanced Materials Jiangsu National Synergetic Innovation Center for Advanced MaterialsNanjing Tech UniversityNanjing 211816China Department of General Dentistry Affiliated Stomatological Hospital of Nanjing Medical UniversityJiangsu Province Key Laboratory of Oral DiseasesNanjing 210029China Research Center for Environmental Nanotechnology(ReCENT) State Key Laboratory of Pollution Control and Resources ReuseSchool of EnvironmentNanjing UniversityNanjing 210023China

Phase manipulation of MoS_(2) from thermodynamically stable 2H phase to the unstable but more reactive 1. phase represents a crucial strategy for improving the reactivity in many *** widely adopted wet chemistry approach uses intercalating entities especially alkali metal ions to achieve the phase transition;however,these entities are normally inert for the target ***,we describe the first use of iron atoms for the intercalation of 2H-MoS_(2) layers,driving the partial transition from 2H to 1. ***,in the peroxymonosulfate(PMS)-based Fenton-like reactions,the interlayered confinement of Fe atoms not only activates the inert basal plane,but also adds more reactive Fe sites for the formation of metal-PMS complex as primary reactive species for pollutant *** the degradation of a model pollutant carbamazepine(CBZ),the Fe-intercalated MoS_(2) exhibits a first order rate constant 1..3 times higher than 2H-MoS_(2).This strategy is a new direction for manipulating the phase composition and boosting the catalytic reactivity of MoS_(2)-based catalysts in various scenarios,including environmental remediation and energy applications.

关键词： confinement MoS_(2) Fe atoms Fenton-like reactions hydrogen evolution reaction

Diminishing the Perception Bias in the Working Environment Using a Network Generation-Based Framework

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2024年第3期29卷 671-683页

作者： Jun qian Tongda Zhang Xiao Sun Yueting Chai Department of Automation Tsinghua UniversityBeijing 100084China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055Chinaand with Systems Optimization LaboratoryStanford UniversityPalo AltoCA 94305USA

Income inequality is widespread in human society and has important implications for human ***’s perception of the environment bridges income inequality and individual behavioral *** research suggests that social income inequality is usually biased,either overestimated or ***,such phenomena have not been fully explored with quantitive prove,especially in the working environment based on performance data of actual *** fact,the correct perception of people is the basis of a fair environment for their production ***,the perception bias may weaken the adaptability and competitiveness of a company in the *** paper first confirms the prevalence of individual perception bias of income inequality within the working environment based on actual production *** results show that people tend to underestimate income inequity around them,and this underestimation grows with the real unfairness of the working ***,this paper proposes a network generation-based framework with a three-layer structure to correct perception bias using a cooperative network reengineering *** the framework,a homophily-based generative network model is proposed as the key *** simulation results show that our proposed framework effectively reduces individuals’perception bias of income inequality.

关键词： income inequality perception bias Gini coefficient factory production cooperative networkreengineering homophily-based generative network model

Combined effect of WS_(2) and Ti_(3)C_(2)T_(x) MXene favors oil-based ultra-low friction on rough steel-steel interface at elevated temperatures

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第7期67卷 1991-2002页

作者： LIU YangQin CHEN Lei WANG Yang qian LinMao Tribology Research Institute State Key Laboratory of Rail Transit Vehicle SystemSchool of Mechanical EngineeringSouthwest Jiaotong UniversityChengdu 610031China Key Laboratory of Advanced Technologies of Materials(Ministry of Education) Research Institute of Frontier ScienceSouthwest Jiaotong UniversityChengdu 610031China

The lubrication performance of liquids is severely restricted and is degraded in high-temperature environments. Stable and reliable lubrication in high temperature environments has been a long-standing goal in various industrial fields. In this study,WS_(2)and Ti_(3)C_(2)T_(x)MXene nanoflakes were used as oil-based lubricant additives to generate ultra-low friction and even superlubricity(friction coefficient of ~0.007) at elevated temperatures(400℃), which has hitherto not been achieved by both individual pristine materials, WS_(2)and Ti_(3)C_(2)T_(x)MXene. Viscosity and thermogravimetric characterization revealed improvements in the high-temperature rheological properties and thermal stability of the lubricating base oil, indicating improved loadbearing and continuous lubrication capabilities at elevated temperatures. X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy demonstrated that the formation of an iron/titanium/tungsten-rich oxide lubricious thin film at the sliding interface reduced the interfacial shear stress, which was responsible for the observed friction and wear reductions at high contact pressures(> 1.1.GPa). Although the titanium/tungsten oxide film was gradually removed after prolonged sliding, a sufficiently thick iron oxide film maintained a low friction coefficient for at least 2 h. The improved surface quality facilitates the achievement of ultra-low friction and reduced wear. The proposed lubrication methodology has a broad utilization potential as a wear-reduction strategy across various industrial fields at elevated temperatures.

关键词： ultra-low friction high-temperature wear reduction lubricating additive tungsten disulfide MXene

Influence of laser parameters on the microstructures and surface properties in laser surface modification of biomedical magnesium alloys

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2024年第1期12卷 72-97页

作者： Chee Ying Tan Cuie Wen Hua qian Ang School of Engineering RMIT UniversityMelbourneVictoria 3001Australia

Biodegradable implants from magnesium(Mg)alloys have emerged in the biomedical field especially in the orthopedic and cardiovascular stent applications owing to their low density,high specific strength,excellent machinability,good biocompatibility,and *** primary shortcoming of Mg-based implants is their low corrosion resistance in the physiological environment,which results in premature mechanical integrity loss before adequate healing and the production of excessive hydrogen gas,which is harmful to the body tissues and negatively affects the biocompatibility of the *** surface modification has recently received attention because it can improve the surface properties such as surface chemistry,roughness,topography,corrosion resistance,wear resistance,hydrophilicity,and thus cell response to the surface of the *** composition and microstructures including textures and phases of laser-treated surfaces depend largely on the laser processing parameters(input laser power,laser scan velocity,frequency,pulse duration,pressure,gas circulation,working time,spot size,beam focal position,and laser track overlap)and the thermophysical properties of the substrate(solubility,melting point,and boiling point).This review investigates the impacts of various laser surface modification techniques including laser surface melting,laser surface alloying,laser cladding,laser surface texturing,and laser shock peening,and highlights their significance in improving the surface properties of biodegradable Mg alloys for implant ***,we explore how different laser process parameters affect its composition,microstructure,and surface properties in each laser surface modification technique.

关键词： Biocompatibility Biodegradability Corrosion Implant applications Laser surface modification Magnesium alloys

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2024年第2期13卷 333-346页

作者： Yifan Sun qian Li Ling-Jun Kong Xiangdong Zhang Key Laboratory of advanced optoelectronic quantum architecture and measurements of Ministry of Education Beijing Key Laboratory of Nanophotonics&Ultrafine Optoelectronic SystemsSchool of PhysicsBeijing Institute of Technology100081BeijingChina

Compared with electrical neural networks,optical neural networks(ONNs)have the potentials to break the limit of the bandwidth and reduce the consumption of energy,and therefore draw much attention in recent *** far,several types of ONNs have been ***,the current ONNs cannot realize the acceleration as powerful as that indicated by the models like quantum neural *** to construct and realize an ONN with the quantum speedup is a huge ***,we propose theoretically and demonstrate experimentally a new type of optical convolutional neural network by introducing the optical *** is called the correlated optical convolutional neural network(COCNN).We show that the COCNN can exhibit“quantum speedup”in the training *** character is verified from the two *** is the direct illustration of the faster convergence by comparing the loss function curves of the COCNN with that of the traditional convolutional neural network(CNN).Such a result is compatible with the training performance of the recently proposed quantum convolutional neural network(QCNN).The other is the demonstration of the COCNN’s capability to perform the QCNN phase recognition circuit,validating the connection between the COCNN and the ***,we take the COCNN analog to the 3-qubit QCNN phase recognition circuit as an example and perform an experiment to show the soundness and the feasibility of *** results perfectly match the theoretical *** proposal opens up a new avenue for realizing the ONNs with the quantum speedup,which will benefit the information processing in the era of big data.

关键词： process quantum convolution