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Unlocking high-efficiency oxygen evolution reaction through Co-N coordination engineering in Co@N-doped porous carbon core–shell nanoparticles

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Nano Research 2024年第8期17卷 7068-7076页

作者： Shucheng liu Yu Shuai Xiaosi Qi zhao Ding Yi liu College of Big Data and Information Engineering Guizhou UniversityGuiyang 550025China College of Physics Guizhou Province Key Laboratory for Photoelectrics Technology and ApplicationGuizhou UniversityGuiyang 550025China

Modulation of metal sites coordination can significantly refine the electronic architecture of catalysts,thereby improving their catalytic *** work successfully developed a core–shell Co@N-doped porous carbon(Co@NC)catalyst by pyrolyzing the COF/MOF(IISERP-COF3/ZIF-67)composite in an inert *** Co@NC catalyst exhibited impressive oxygen evolution reaction(OER)performance,with a small overpotential of 304 mV and a modest Tafel slope of 88.6 mV·dec^(−1) in a 1 M KOH,alongside remarkable stability,maintaining 98.5%of its activity over 13 *** role of IISERP-COF3 was pivotal in preventing Co atom aggregation during the ZIF-67 pyrolysis,which facilitated the creation of mesopores for enhanced mass transport and ***,it effectively modulated the Co-N coordination to fine-tune the electronic structure,thereby optimizing the catalyst's capacity for adsorption of intermediates and boosting its intrinsic *** functional theory(DFT)studies corroborate that the exceptional OER efficiency of Co@NC can be linked to the enhanced Co-N coordination,optimizing the localized electronic structure at the Co active *** study not only proposes an innovative approach for optimizing COF/MOF as effective electrocatalysts but also clears the path for the emergence of affordable,high-performance alternatives to precious metal-based catalysts,marking a significant advancement in sustainable energy technologies.

关键词： covalent organic framework(COF) metal-organic framework(MOF) core-shell structure catalysts oxygen evolution reaction

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A novel small-signal equivalent circuit model for GaN HEMTs incorporating a dual-field-plate

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Journal of Semiconductors 2024年第5期45卷 61-68页

作者： Jinye Wang Jun liu Zhenxin zhao School of Integrated Circuit Science and Engineering Hangzhou Dianzi UniversityHangzhou 310018China

An accurate and novel small-signal equivalent circuit model for GaN high-electron-mobility transistors(HEMTs)is proposed,which considers a dual-field-plate(FP)made up of a gate-FP and a *** equivalent circuit of the overall model is composed of parasitic elements,intrinsic transistors,gate-FP,and source-FP *** equivalent circuit of the gate-FP is identical to that of the intrinsic *** order to simplify the complexity of the model,a series combination of a resistor and a capacitor is employed to represent the *** analytical extraction procedure of the model parameters is presented based on the proposed equivalent *** verification is carried out on a 4×250μm GaN HEMT device with a gate-FP and a source-FP in a 0.45μm *** with the classic model,the proposed novel small-signal model shows closer agreement with measured S-parameters in the range of 1.0 to 18.0 GHz.

关键词： small-signal model dual field-plate(FP) GaN high-electron-mobility transistors(HEMT) parameter extraction

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publication-level analysis of Journal of Plant Ecology during 2018-2022

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Journal of Plant Ecology 2024年第4期17卷 197-201页

作者： Yu Liao pu Wang Lijuan liu Wen-Hao Zhang National Science Library Chinese Academy of SciencesBeijing 100190China Center for Documentation and Information Institute of BotanyChinese Academy of SciencesBeijing 100093China State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China

Journal of Plant Ecology(JPE)was established in 2008 and is sponsored by the Botanical Society of China and the Institute of Botany,Chinese Academy of *** by Oxford University Press,UK,JPE encompasses a wide range of article types within the expansive field of plant *** of July 2021,JPE has transitioned to fully Open Access,ensuring unrestricted access to the full text for both readers and *** shift enhances the journal’s role as a crucial platform for plant ecologists worldwide to disseminate their research findings.

关键词： Open Plant Access

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Design of digital calibration based on variable step size of sub-binary SAR ADC

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The Journal of China Universities of Posts and Telecommunications 2024年第2期31卷 62-71页

作者： liu Wei zhao Yanke Shang Shiguang School of Electronic Engineering Xi'an University of Posts and TelecommunicationsXi'an 710121China

Addressing the impact of capacitor mismatch on the conversion accuracy of successive approximation register analog-to-digital converter(SAR ADC),a 12-bit 1 MS/s sub-binary SAR ADC designed using variable step size digital calibration was *** least mean square(LMS)calibration algorithm was employed with a ramp signal used as the calibration *** errors,extracted under injected disturbances,underwent iterative training to optimize weight *** address the trade-off between conversion accuracy and speed caused by a fixed step size,a novel variable step size algorithm tailored for SAR ADC calibration was *** core circuit and layout of the SAR ADC were implemented using the Taiwan Semiconductor Manufacturing Company(TSMC)0.35μm complementary metal-oxide-semiconductor(CMOS)commercial *** of the SAR ADC calibration algorithm was conducted using Simulink,demonstrating quick convergence and meeting conversion accuracy requirements compared to fixed step size *** results indicated that the convergence speed of the LMS digital calibration algorithm with variable step size was approximately eight times faster than that with a fixed step size,also yielding a lower mean square error(MSE).After calibration,the simulation results for the SAR ADC exhibited an effective number of bit(ENOB)of 11.79 bit and a signal-to-noise and distortion ratio(SNDR)of 72.72 dB,signifying a notable enhancement in the SAR ADC performance.

关键词： successive approximation register analog-to-digital converter(SAR ADC) variable step size digital calibration disturbance technique

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Differences and similarities in radial growth of Betula species to climate change

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Journal of Forestry Research 2024年第2期35卷 176-187页

作者： Di liu Yang An zhao Li Zhihui Wang Yinghui zhao Xiaochun Wang Center for Ecological Research Key Laboratory of Sustainable Forest Ecosystem ManagementMinistry of EducationCollege of ForestryNortheast Forestry UniversityHarbin 150040People’s Republic of China Changan Park in Shijiazhuang Shijiazhuang 050000People’s Republic of China Shijiazhuang Landscape Greening Engineering Project Construction Center Shijiazhuang 050000People’s Republic of China Heilongjiang Institute of Meteorological Science Harbin 150030People’s Republic of China School of Life Qufu Normal UniversityQufu 273100People’s Republic of China

Betula platyphylla and Betula costata are important species in mixed broadleaved-Korean pine(Pinus koraiensis)***,the specific ways in which their growth is affected by warm temperatures and drought remain *** address this issue,60 and 62 tree-ring cores of *** and *** were collected in Yichun,*** dendrochronological methods,the response and adaptation of these species to climate change were examined.A“hysteresis effect”was found in the rings of both species,linked to May–September moisture conditions of the previous *** growth of *** was positively correlated with the standardized precipitation-evapotranspiration index(SPEI),the precipitation from September to October of the previous year,and the relative humidity in October of the previous *** of *** is primarily restricted by moisture conditions from September to *** contrast,*** growth is mainly limited by minimum temperatures in May–June of both the previous and current *** droughts,*** had a faster recovery rate compared to *** the context of rising temperatures since 1980,the correlation between *** growth and monthly SPEI became positive and strengthened over time,while the growth of *** showed no conspicuous *** findings suggest that the growth of *** is already affected by warming temperatures,whereas *** may become limited if warming continues or *** change could disrupt the succession of these species,possibly accelerating the succession of pioneer *** results of this research are of great significance for understanding how the growth changes of birch species under warming and drying conditions,and contribute to understanding the structural adaptation of mixed broadleaved-Korean pine(Pinus koraiensis)forests under climate change.

关键词： Tree rings Betula platyphylla Betula costata Climate response Moving correlation Extreme drought

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Cobalt-catalyzed deoxygenative borylation of diaryl ketones

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Chinese Chemical Letters 2024年第3期35卷 277-281页

作者： Longqing liu Bing Zhang Yu liu Jinbo zhao Tao Li Wanxiang zhao College of Chemistry and Life Science Changchun University of TechnologyChangchun 130012China State Key Laboratory of Chemo/Biosensing and Chemometrics College of Chemistry and Chemical EngineeringHunan UniversityChangsha 410082China

Geminal diboronates and diarylmethyl boronates are versatile building blocks in synthetic *** here reported a highly efficient approach for the synthesis of gem-bisborylalkanes and diarylmethyl boronates via cobalt-catalyzed deoxygenative borylation of diaryl *** borylation protocol is compatible with a broad range of functionalized aryl groups,providing access to a wide array of boronic *** resulting boronic esters can be further transformed to various cross-coupling products and TPEs that represent important structural motifs in organic chemistry and materials science.

关键词： Bisborylalkanes Cobalt Deoxygenative borylation Ketones

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Transition metal clusters with precise numbers of atoms anchored on graphdiyne as multifunctional electrocatalysts for OER/ORR/HER:a computational study

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Rare Metals 2024年第7期43卷 3107-3117页

作者： Xin-Yang liu Jing-Wei liu Gang Li Jing-Xiang zhao College of Chemistry and Chemical Engineering Harbin Normal UniversityHarbin 150025China

Subnanometer metal clusters play an increasingly important role in heterogeneous catalysis due to their high catalytic activity and *** this work,by means of the density functional theory(DFT) calculations,the catalytic activities of transition metal clusters with precise numbers of atoms supported on graphdiyne(TM_(1-4)@GDY,TM=V,Cr,Mn,Fe,Co,Ni,Cu,Ru,Rh,Pd,Ir,Pt) were investigated for oxygen evolution reactions(OER),oxygen reduction reactions(ORR) and hydrogen evolution reactions(HER).The computed results reveal that the Pd_(2),Pd_(4) and Pt_(1) anchored graphdiyne can serve as trifunctional catalysts for OER/ORR/HER with the overpotentials of 0.49/0.37/0.06,0.45/0.33/0.12 and 0.37/0.43/0.01 V,respectively,while Pd_(1) and Pt_(2)@graphdiyne can exhibit excellent catalytic performance for water splitting(OER/HER) with the overpotentials of 0.55/0.17 and 0.43/0.03 *** addition,Ni_(1) and Pd_(3) anchored GDY can perform as bifunctional catalysts for metal-air cells(OER/ORR) and fuels cells(ORR/HER) with the overpotentials of 0.34/0.32 and 0.42/0.04 V,***,by precisely controlling the numbers of atoms in clusters,the TM_(1-4) anchored graphdiyne can serve as promising multifunctional electrocatalysts for OER/ORR/HER,which may provide an instructive strategy to design catalysts for the energy conversation and storage devices.

关键词： Density functional theory Graphdiyne Single-cluster catalysts Multifunctional electrocatalysts Overpotential

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Chemodivergent Synthesis of Benzofurans and 2,3-Dihydrobenzofurans via Tandem Oxidative Annulation of Enaminones and Salicylaldehydes

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Chinese Journal of Chemistry 2024年第15期42卷 1727-1733页

作者： Xiyan Duan Hui Li Junqi Wang Kun liu Meixin Shi Weidong Lian Ran Chen pu liu School of Chemistry&Chemical Engineering Henan University of Science and TechnologyLuoyangHenan 471003China

Chemodivergent synthesis of benzofurans and 2,3-dihydrobenzofurans has been *** a reaction system consisting of DBDMH and K_(2)CO_(3) as promotors,controlled conditions enabled the formation of two sets of valuable heterocycles from the tandem transformation of enaminones and *** key to success was the identification of the reaction parameters,in which the imine intermediate which was formed by transient halogenation coupling and substitution processes underwent either aldol condensation/annulation or imine hydrolysis/aldol *** additives NH_(4)Cl or Fe_(2)(SO_(4))_(3) controlled the unique selectivity of this reaction.A broad substrate scope of enaminones and salicylaldehydes has been employed in this reaction,demonstrating excellent functional group tolerance and versatility.

关键词： Cross-coupling Umpolung Domino reactions Enaminone Benzofurans 2,3-Dihydrobenzofurans

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Elucidating the enhancement of kaolinite flotation by iron content through density functional theory: A study on sodium oleate adsorption efficiency

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International Journal of Mining Science and Technology 2024年第6期34卷 855-866页

作者： Lingyun liu Chuilei Kong Hongyu zhao Fangqin Lu Joint National-Local Engineering Research Centre for Safe and Precise Coal Mining Huainan 232001China Department of Materials Science and Engineering Anhui University of Science and TechnologyHuainan 232001China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China

This study delves into the intricate relationship between iron(Fe)content in kaolinite and its impact on the adsorption behavior of sodium *** effects of different iron concentrations on adsorption energy,hydrogen bond kinetics and adsorption efficiency were studied through simulation and experimental *** results show that the presence of iron in the kaolinite structure significantly improves the adsorption capacity of sodium *** samples with high iron content have better adsorption properties,lower adsorption energy levels and shorter and stronger hydrogen bonds than pure *** optimal concentration of oleic acid ions for achieving maximum adsorption efficiency was identified as 1.2 mmol/L across different kaolinite *** this concentration,the adsorption rates and capacities reach their peak,with Fe-enriched kaolinite samples exhibiting notably higher flotation recovery *** optimal concentration represents a balance between sufficient oleic acid ion availability for surface interactions and the prevention of self-aggregation phenomena that could hinder *** study offers promising avenues for optimizing the flotation process in mineral processing applications.

关键词： Iron Influence Sodium Oleate Adsorption Kaolinite Surfaces Molecular Interaction Analysis Flotation Efficiency Optimization

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Singularity analysis and avoidance for an SSRMS-type reconfigurable space manipulator with a non-spherical wrist and two lockable passive telescopic links

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Chinese Journal of Aeronautics 2024年第8期37卷 435-459页

作者： Zhiyuan zhao Xiaohang YANG Yuntao LI Zichun XU Jingdong zhao Hong liu State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China

This study focuses on addressing kinematic singularity analysis and avoidance issues for a space station remote manipulator system(SSRMS)-type reconfigurable space *** manipulator is equipped with a non-spherical wrist and two lockable passive telescopic links(LPTLs),which enable it to have both active revolute and passive prismatic joints and operate in two distinct *** begin with the kinematic singularity analysis,the study derives the differential kinematic equations for the manipulator and identifies the dominant Jacobian matrix that causes ***,an in-depth analysis of singularities from multiple perspectives is ***,a kinematic singularity map method is proposed to capture the distribution of singularities within the reachable ***,the influence of the two LPTLs on singularities is thoroughly ***,a new method based on the matrix rank equivalence principle is introduced to determine singularity conditions,enabling the identification of all the singular configurations for the SSRMS-type reconfigurable ***,this method significantly reduces computational complexity,and the singularity conditions obtained have more concise *** the singularity avoidance problem,a novel method is developed,which simultaneously addresses the requirements of real-time performance,high precision,and the avoidance of both kinematic singularities and joint limit *** from these excellent properties,the proposed method can effectively resolve the singularity issues encountered separately by the SSRMS-type reconfigurable manipulator in its two operational *** typical simulations validate the utility of all the proposed methods.

关键词： Reconfigurable space manipulator Redundant manipulator Kinematics Singularity analysis Singularity avoidance

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