检索结果-南通市图书馆

Highly selective and eco-friendly dihydroisoquinoline synthesis via Cu/Co synergistic catalysis in Cu NPs@MOFs catalyst under mild conditions

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第5期67卷 1561-1568页

作者： Peng-Fei Guo Ze-long Liang Yue-E jiao Hang Xu Bin Zhao Key Laboratory of Advanced Energy Material Chemistry Renewable Energy Conversion and Storage CenterDepartment of ChemistryNankai UniversityTianjin 300071China

3,4-Dihydroisoquinoline(DHIQ)is an important precursor used in the production of drugs for treating cancer,HIV,Alzheimer's disease,*** studies on DHIQ synthesis show low catalytic selectivity due to the susceptible over-oxidation feedstock of1,2,3,4-tetrahydroisoquinoline(THIQ),which often requires alkali ***,it is desirable yet challenging to explore a highly selective and efficient oxydehydrogenation capacity for DHIQ synthesis under eco-friendly reaction ***,a novel framework 1 was synthesized,exhibiting 1D channels with the size of 4.6 A×9.6 A and high solvent/p H/thermal stability.A stable framework allows it to encapsulate Cu nanoparticles(NPs)to form Cu NPs@1-x(x=1,2,3,and 4)with varying loading amounts of Cu NPs at 2.0 wt%,3.0 wt%,4.0 wt%,and 6.0 wt%,*** NPs@1-3 could selectively catalyze the reaction from THIQ to DHIQ with a high selectivity of 98%and a recorded turnover frequency(TOF)of 22.1 h-1under eco-friendly mild *** corresponding catalytic activity can maintain at least five recyclings and can be further applied to gram-scale ***,the efficient preparation of DHIQ catalyzed by Cu NPs@1-3 could be realized even under air ***,the anticancer molecule precursor synthesis of 6,7-dimethoxy-3,4-dihydroisoquinoline was also selectively catalyzed by Cu NPs@*** investigations revealed that high catalytic performance can be attributed to the stable framework and the synergistic catalytic effect of the loaded Cu NPs and Co metal *** importantly,this work represents the first example of MOF catalysts for selectively thermo-catalytic DHIQ synthesis and demonstrates a simple approach to obtain efficient catalysts for selective oxydehydrogenation in the production of unsaturated compounds.

关键词： metal-organic frameworks Cu NPs@MOFs 3 4-dihydroisoquinoline selective oxydehydrogenation synergistic catalysis

High spectral efficiency 4-mode 400-km transmission using hybrid probabilistically and geometrically shaped 128QAM

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第5期67卷 1628-1630页

作者： DING JunJie YU JianJun WANG Chen long JianYu ZHU Min ZHANG jiao Pervasive Communication Research Center Purple Mountain LaboratoriesNanjing 211111China Key Laboratory for Information Science of Electromagnetic Waves(MoE) Fudan UniversityShanghai 200433China

Wavelength division multiplexing(WDM)and space division multiplexing(SDM)based on few-mode fiber(FMF)and multi-core fiber(MCF)have been vigorously developed to increase the transmission capacity of optical communication networks[1–5].However,the mode crosstalk generated in the mode division multiplexing(MDM)system causes the correlation between different mode signals,which seriously damages the transmission ***,an effective multiple-input-multiple-output(MIMO)time domain or frequency domain equalizer should be used to eliminate the crosstalk between different mode signals.

关键词： crosstalk fiber multiplexing

Influence of Micro/Nano-Ti Particles on the Corrosion Behavior of AZ31-Ti Composites

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 484-498页

作者： jinchao jiao jin Zhang Yong Lian Shengli Han Kaihong Zheng Fusheng Pan Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 10083China Beijing Key Laboratory for Corrosion Erosion and Surface Technology Beijing 100083China Institute of New Materials Guangdong Academy of SciencesGuangzhou 510650China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 404100China

Adding Ti particles to magnesium alloy simultaneously enhances its strength and ***,how these particles influence on Mg alloy’s corrosion performance is seldom *** corrosion behavior of AZ31-Ti composites containing titanium nanoparticles(1.5 and 5 wt%)and micron particles(10 wt%)prepared by powder metallurgical in 3.5 wt%NaCl solution was *** results indicate that Ti particles serve as the primary location for the cathodic hydrogen reduction reaction,resulting in intense galvanic corrosion between the Ti and Mg *** nanoparticles distributed at the interface of the original AZ31 powder were in a discontinuous mesh structure,thus failing to act as a barrier against *** corrosion products with the existence of numerous cracks gradually peel off during the corrosion process and cannot protect the *** average corrosion rate P_(w) of AZ31,AZ31-1.5%Ti,AZ31-5%Ti,and AZ31-10%Ti after 7 days of immersion is 27.55,105.65,283.67,and 99.35 mm/y,***,AZ31-Ti composites can be considered as potential candidates for degradable fracturing ***,it is recommended to improve their corrosion resistance through surface treatment.

关键词： AZ31-Ti composite Nano-Ti Micro-Ti Corrosion behavior Scanning Kelvin probe force microscopy(SKPFM)

Evolution model and failure mechanisms of rainfall-induced cracked red clay slopes:insights from Xinshao County,China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain Science 2024年第3期21卷 867-881页

作者： jiao Weizhi ZHANG Ming LI Peng XIE Junjin PANG Haisong LIU Fuxing YANG long Faculty of Engineering China University of GeosciencesWuhan 430074China

Red clay landslides are widely distributed worldwide,resulting in severe loss of life and *** rainfall-induced red clay slopes have received extensive attention,the role of cracks in the evolutionary process of red clay slopes and their connection to failure mechanisms is still poorly understood.A comprehensive approach integrating field investigation,laboratory tests,and numerical simulations was conducted to study the 168 red clay landslides in Xinshao County,*** results show that red clay is prone to forming cracks at high moisture content due to its low swelling and high shrinkage *** failure mode of red clay slopes can be summarized in three stages:crack generation,slope excavation,and slope ***,the retrospective analysis and numerical simulations of the typical landslide in Guanchong indicated that intense rainfall primarily impacts the shallow layer of soil within approximately 0.5 m on the intact ***,cracks change the pattern of rainfall infiltration in the *** infiltrates rapidly through the preferential channels induced by the cracks rather than uniformly and slowly from the slope *** results in a significant increase in both the depth of infiltration and the saturated zone area of the cracked slope,reaching 3.8 m and 36.2 m^(2),***,the factor of safety of the slope decreases by 13.4%compared to the intact slope,ultimately triggering *** study can provide valuable insights into understanding the failure mechanisms of red clay slopes in China and other regions with similar geological settings.

关键词： Red clay slopes Cracks Preferential flow Failure mechanism

The shear strength of the interface between artificial rock and printed concrete at super-early ages

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2024年第1期18卷 51-65页

作者： Yong Yuan Xiaoyun Wang jiao-long Zhang Yaxin Tao Kim Van Tittelboom Luc Taerwe Geert De Schutter College of Civil Engineering Tongji UniversityShanghai 200092China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China Belgium-China Joint Laboratory for Industrialized Construction Tongji UniversityShanghai 200092China Magnel-Vandepitte Laboratory for Structural Engineering and Building Materials Ghent UniversityGhent 9052Belgium

3D concrete printing has the potential to replace shotcrete for construction of linings of tunnels in hard *** shear strength of the interface between rock and printed concrete is vital,especially at super-early ***,traditional methods for testing the shear strength of the interface,e.g.,the direct shear test,are time-consuming and result in a high variability for fast-hardening printed *** this paper,a new fast bond shear test is *** test can be completed in 1 min,with another 2 min for preparing the next *** influence of the matrix composition,the age of the printed matrices,and the interface roughness of the artificial rock substrate on the shear strength of the interface was experimentally *** tests were conducted at the age of the matrices at the 1st,the 4th,the 8th,the 16th,the 32nd,and the 64th min after its final setting.A dimensionless formula was established to calculate the shear strength,accounting for the age of the printed matrices,the interface roughness,and the shear failure *** was validated by comparing the calculated results and the experimental results of one group of samples.

关键词： rock tunnel printed concrete interface fast bond shear test shear strength

Engineering g-C_(3)N_(4)based materials for advanced photocatalysis:Recent advances

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Green Energy & Environment 2024年第2期9卷 166-197页

作者： Xin-Lian Song Lei Chen Li-jiao Gao jin-Tao Ren Zhong-Yong Yuan National Institute for Advanced Materials School of Materials Science and EngineeringSmart Sensing Interdisciplinary Science CenterNankai UniversityTianjin300350China Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) Nankai UniversityTianjin300071China

Photocatalysis driven by abundant yet intermittent solar energy has considerable potential in renewable energy generation and environmental *** outstanding electronic structure and physicochemical properties of graphitic carbon nitride(g-C_(3)N_(4)),together with unique metal-free characteristic,make them ideal candidates for advanced photocatalysts *** review summarizes the up-to-date advances on g-C_(3)N_(4)based photocatalysts from ingenious-design strategies and diversified photocatalytic ***,the advantages,fabrication methods and limitations of each design strategy are systemically *** order to deeply comprehend the inner connection of theory–structure–performance upon g-C_(3)N_(4)based photocatalysts,structure/composition designs,corresponding photocatalytic activities and reaction mechanisms are jointly discussed,associated with introducing their photocatalytic applications toward water splitting,carbon dioxide/nitrogen reduction and pollutants degradation,***,the current challenges and future perspectives for g-C_(3)N_(4)based materials for photocatalysis are briefly *** design strategies and limitations are also instructive for constructing g-C_(3)N_(4) based materials in other energy and environment-related applications.

关键词： Graphitic carbon nitride g-C_(3)N_(4) Design strategies Photocatalysis Photocatalysts Reaction mechanism

A statistical analysis of the Kappa-type energy spectrum distribution of radiation belt electrons observed by Van Allen Probes

在线全文

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2024年第2期8卷 368-374页

作者： LuHuai jiao Xin Ma YuanNong Zhang TaiFeng jin Song Fu BinBin Ni Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China

The energy spectrum of energetic electrons is a key factor representing the dynamic variations of Earth’s Van Allen radiation *** measurements have indicated that the commonly used Maxwellian and Kappa distributions are inadequate for capturing the realistic spectral distributions of radiation belt *** we adopt the Kappa-type(KT)distribution as the fitting function and perform a statistical analysis to investigate the radiation belt electron flux spectra observed by the Van Allen *** calculating the optimal values of the key KT distribution parameters(i.e.,κandθ2)from the observed spectral shapes,we fit the radiation belt electron fluxes at different L-shells under different geomagnetic *** this manner,we obtain typical values of the KT distribution parameters,which are statistically feasible for modeling the radiation belt electron flux profiles during either geomagnetically quiet or active periods.A comparison of the KT distribution model results with those using the Maxwellian or Kappa distribution reveals the advantage of the KT distribution for studying the overall properties of the radiation belt electron spectral distribution,which has important implications for deepening the current understanding of the radiation belt electron dynamics under evolving geomagnetic conditions.

关键词： radiation belt electron Kappa-type distribution fitting geomagnetic storm

Honeycomb-like MoCo alloy on 3D nitrogen-doped porous graphene for efficient hydrogen evolution reaction

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第3期43卷 1072-1082页

作者： Lin-Ping Wang Kuang Li Hua-long Ding Le Xu Chen Huang jiao-jiao Zhou Cong-TaoWen Pei-Lin Zhang Wei-Wei Wang Lu-Yang Chen Key Laboratory for Ultrafine Materials of Ministry of Education School of Materials Science and EngineeringEast China University of Science and TechnologyShanghai200237China State Key Laboratory of High-Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics Chinese Academy of SciencesShanghai200050China State Key Laboratory of Chemical Engineering and School of Chemistry and Molecular Engineering East China University of Science and TechnologyShanghai200237China

An efficient electrocatalyst is indispensable to significantly reduce energy consumption and accelerate the conversion efficiency of water *** this work,the honeycomb-like porous MoCo alloy on nitrogen-doped three-dimensional(3D)porous graphene substrate(Mo_(0.3)Co_(0.7)@NPG)has been synthesized from the annealing of layered double hydroxide(MoCo-LDH@NPG).Especially,the Mo_(0.3)Co_(0.7)@NPG exhibits low hydrogen evolution overpotential of 75 mV(10 mA·cm^(-2))and a Tafel slope of 69.9 mV·dec^(-1),which can be attributed to highly conductive NPG substrate,the unique nanostructure and the synergistic effect of Mo and ***,the Mo_(0.3)Co_(0.7)@NPG can maintain the original morphology and high catalytic activity after 50-h stability *** work proposes a general strategy to synthesize a multi-element alloy on conductive substrates with high porosity for electrocatalytic reaction.

关键词： MoCo alloy Three-dimensional nitrogen-doped porous graphene Hydrogen evolution reaction(HER)

RoBGP:A Chinese Nested Biomedical Named Entity Recognition Model Based on RoBERTa and Global Pointer

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第3期78卷 3603-3618页

作者： Xiaohui Cui Chao Song Dongmei Li Xiaolong Qu jiao long Yu Yang Hanchao Zhang School of Information Science and Technology Beijing Forestry UniversityBeijing100083China Engineering Research Center for Forestry-Oriented Intelligent Information Processing of National Forestry and Grassland Administration Beijing100083China Division of Biostatistics Department of Population HealthGrossman School of MedicineNew York UniversityNew York10016USA

Named Entity Recognition(NER)stands as a fundamental task within the field of biomedical text mining,aiming to extract specific types of entities such as genes,proteins,and diseases from complex biomedical texts and categorize them into predefined entity *** process can provide basic support for the automatic construction of knowledge *** contrast to general texts,biomedical texts frequently contain numerous nested entities and local dependencies among these entities,presenting significant challenges to prevailing NER *** address these issues,we propose a novel Chinese nested biomedical NER model based on RoBERTa and Global Pointer(RoBGP).Our model initially utilizes the RoBERTa-wwm-ext-large pretrained language model to dynamically generate word-level initial *** then incorporates a Bidirectional long Short-Term Memory network for capturing bidirectional semantic information,effectively addressing the issue of long-distance ***,the Global Pointer model is employed to comprehensively recognize all nested entities in the *** conduct extensive experiments on the Chinese medical dataset CMeEE and the results demonstrate the superior performance of RoBGP over several baseline *** research confirms the effectiveness of RoBGP in Chinese biomedical NER,providing reliable technical support for biomedical information extraction and knowledge base construction.

关键词： Biomedicine knowledge base named entity recognition pretrained language model global pointer