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Rebuilding the theory of isotope fractionation for evaporation of silicate melts under vacuum condition

Acta Geochimica 2024年第4期43卷 661-676页

作者： Jie Wang Yun Liu research Center for Planetary Science College of Earth and Planetary SciencesChengdu University of TechnologyChengdu 610059China State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China CAS Center for Excellence in Comparative Planetology Hefei 230026China

Isotope eff ects are pivotal in understanding silicate melt evaporation and planetary accretion *** on the Hertz-Knudsen equation,the current theory often fails to predict observed isotope fractionations of laboratory experiments due to its oversimplified ***,we point out that the Hertz-Knudsen-equation-based theory is incomplete for silicate melt evaporation cases and can only be used for situations where the vaporized species is identical to the one in the *** propose a new model designed for silicate melt evaporation under *** model considers multiple steps including mass transfer,chemical reaction,and *** derivations reveal a kinetic isotopic fractionation factor(KIFF orα)αour model=[m(^(1)species)/m(^(2)species)]^(0.5),where m(species)is the mass of the reactant of reaction/nucleation-limiting step or species of diffusion-limiting step and superscript 1 and 2 represent light and heavy isotopes,*** model can eff ectively reproduce most reported KIFFs of laboratory experiments for various elements,i.e.,Mg,Si,K,Rb,Fe,Ca,and ***,the KIFF-mixing model referring that an overall rate of evaporation can be determined by two steps jointly can account for the eff ects of low P_(H2)pressure,composition,and *** addition,we find that chemical reactions,diffusion,and nucleation can control the overall rate of evaporation of silicate melts by using the fitting slope in ln(−ln f)versus ln(t).Notably,our model allows for the theoretical calculations of parameters like activation energy(E_(a)),providing a novel approach to studying compositional and environmental eff ects on evaporation processes,and shedding light on the formation and evolution of the proto-solar and Earth-Moon systems.

关键词： Evaporation Kinetic isotopic fractionation Chemical kinetics Hertz-Knudsen equation CAIS

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Mechanism analysis of regulating Turing instability and Hopf bifurcation of malware propagation in mobile wireless sensor networks

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Chinese Physics B 2024年第6期33卷 125-140页

作者：黄习习肖敏 Leszek Rutkowski 包海波黄霞曹进德 College of Automation&College of Artificial Intelligence Nanjing University of Posts and TelecommunicationsNanjing 210023China Systems research institute of the Polish Academy of Sciences 01-447 WarsawPoland College of Electrical Engineering and Automation Shandong University of Science and TechnologyQingdao 266590China School of Mathematics Southeast UniversityNanjing 210096China

A dynamical model is constructed to depict the spatial-temporal evolution of malware in mobile wireless sensor networks(MWSNs). Based on such a model, we design a hybrid control scheme combining parameter perturbation and state feedback to effectively manipulate the spatiotemporal dynamics of malware propagation. The hybrid control can not only suppress the Turing instability caused by diffusion factor but can also adjust the occurrence of Hopf bifurcation induced by time delay. Numerical simulation results show that the hybrid control strategy can efficiently manipulate the transmission dynamics to achieve our expected desired properties, thus reducing the harm of malware propagation to MWSNs.

关键词： mobile wireless sensor networks reaction-diffusion Hopf bifurcation hybrid control

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Enhanced stability of nitrogen-doped carbon-supported palladium catalyst for oxidative carbonylation of phenol

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Chinese Journal of Chemical Engineering 2024年第1期65卷 19-28页

作者： Xiaojing Liu Ruohan Zhao Hao Zhao Zhimiao Wang Fang Li Wei Xue Yanji Wang Hebei Provincial Key Laboratory of Green Chemical Technology and High Efficient Energy Saving School of Chemical Engineering and TechnologyHebei University of TechnologyTianjin 300130China Tianjin Key Laboratory of Chemical Process Safety Tianjin 300130China Hebei Industrial Technology research institute of Green Chemical Industry Huanghua 061100China

Enhancing the stability of supported noble metal catalysts emerges is a major challenge in both science and ***,a heterogeneous Pd catalyst(Pd/NCF)was prepared by supporting Pd ultrafine metal nanoparticles(NPs)on nitrogen-doped carbon;synthesized by using F127 as a stabilizer,as well as chitosan as a carbon and nitrogen *** Pd/NCF catalyst was efficient and recyclable for oxidative carbonylation of phenol to diphenyl carbonate,exhibiting higher stability than Pd/NC prepared without F127 *** hydrogen bond between chitosan(CTS)and F127 was enhanced by F127,which anchored the N in the free amino group,increasing the N content of the carbon material and ensuring that the support could provide sufficient N sites for the deposition of Pd *** process helped to improve metal *** increased metal-support interaction,which limits the leaching and coarsening of Pd NPs,improves the stability of the Pd/NCF ***,density functional theory calculations indicated that pyridine N stabilized the Pd^(2+)species,significantly inhibiting the loss of Pd^(2+)in Pd/NCF during the reaction *** work provides a promising avenue towards enhancing the stability of nitrogen-doped carbon-supported metal catalysts.

关键词： Supported Pd catalyst N-doped carbon Amphiphilic triblock copolymer Pyridinic nitrogen Stability

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Sparse convolutional model with semantic expression for waste electrical appliances recognition

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Science China(Technological Sciences) 2024年第9期67卷 2881-2893页

作者： HAN HongGui LIU YiMing LI FangYu DU YongPing Faculty of Information Technology Beijing University of TechnologyBeijing 100124China Beijing Key Laboratory of Computational Intelligence and Intelligent System Beijing 100124China Engineering research Center of Digital Community Ministry of EducationBeijing 100124China Beijing Artificial Intelligence institute and Beijing Laboratory for Intelligent Environmental Protection Beijing 100124China

Deep neural networks play an important role in the recognition of waste electrical appliances. However, deep neural network components still lack reliability in decision-making features. To address this problem, a sparse convolutional model with semantic expression(SCMSE) is proposed. First, a low-rank sparse semantic expression component, combining the benefits of residual networks and sparse representation, is adapted to enhance sparse feature extraction and semantic expression. Second, a reliable network architecture is obtained by iterating the optimal sparse solution, enhancing semantic expression. Finally, the results of visualization experiments on the waste electrical appliances dataset demonstrate that the proposed SCMSE can obtain excellent semantic performance.

关键词： sparse convolutional model deep neural network semantic expression visualization computer vision

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Structure and 2p decay mechanism of^(18)Mg

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Nuclear Science and Techniques 2024年第6期35卷 145-154页

作者： Long Zhou De-Qing Fang Si-Min Wang Hui Hua Key Laboratory of Nuclear Physics and Ion-beam Application(MOE) Institute of Modern PhysicsFudan UniversityShanghai 200433China Shanghai research Center for Theoretical Nuclear Physics NSFC and Fudan UniversityShanghai 200438China School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking UniversityBeijing 100871China

The recently discovered,extremely proton-rich nuclide 18 Mg exhibits ground-state decay via two sequential two-proton(2p)emissions through the intermediate nucleus,*** study investigates the structure and the initial 2p decay mechanism of^(18)Mgby examining the density and correlations of the valence protons using a three-body Gamow coupled-channel *** results show that the ground state of^(18)Mgis significantly influenced by the continuum,resulting in a significant s-wave ***,based on the current framework,this does not lead to a significant deviation in mirror symmetry in either the structure or spectroscopy of the 18Mg-18C ***,the time evolution analysis of the^(18)Mgground state suggests a simultaneous 2p emission during the first step of *** observed nucleon-nucleon correlations align with those of the light-mass 2p emitters,indicating a consistent decay behavior within this nuclear region.

关键词： Structure of^(18)Mg Two-proton decay Proton-proton correlation

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STGNN-LMR:A Spatial–Temporal Graph Neural Network Approach Based on sEMG Lower Limb Motion Recognition

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Journal of Bionic Engineering 2024年第1期21卷 256-269页

作者： Weifan Mao Bin Ma Zhao Li Jianxing Zhang Yizhou Lu Zhuting Yu Feng Zhang Shanghai Advanced research institute Chinese Academy of SciencesShanghai 201210China University of Chinese Academy of Sciences Beijing 101408China University of Science and Technology of China Hefei 230026China Shanghai Zhongyan Jiuyi Technology Co. Ltd.Shanghai 201821China Academy of Military Science Bejing 100091China

Lower limb motion recognition techniques commonly employ Surface Electromyographic Signal(sEMG)as input and apply a machine learning classifier or Back Propagation Neural Network(BPNN)for ***,this artificial feature engineering technique is not generalizable to similar tasks and is heavily reliant on the researcher’s subject *** contrast,neural networks such as Convolutional Neural Network(CNN)and Long Short-term Memory Neural Network(LSTM)can automatically extract features,providing a more generalized and adaptable approach to lower limb motion *** this approach overcomes the limitations of human feature engineering,it may ignore the potential correlation among the sEMG *** paper proposes a spatial–temporal graph neural network model,STGNN-LMR,designed to address the problem of recognizing lower limb motion from multi-channel ***-LMR transforms multi-channel sEMG into a graph structure and uses graph learning to model spatial–temporal *** 8-channel sEMG dataset is constructed for the experimental stage,and the results show that the STGNN-LMR model achieves a recognition accuracy of 99.71%.Moreover,this paper simulates two unexpected scenarios,including sEMG sensors affected by sweat noise and sudden failure,and evaluates the testing results using hypothesis *** to the experimental results,the STGNN-LMR model exhibits a significant advantage over the control models in noise scenarios and failure *** experimental results confirm the effectiveness of the STGNN-LMR model for addressing the challenges associated with sEMG-based lower limb motion recognition in practical scenarios.

关键词： Lower limb motion recognition Exoskeleton sEMG.Graph neural network Noise Sensor failure

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Biaxial tensile behavior of CoCrFeNi high-entropy alloy under dynamic and proportional loadings

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Chinese Journal of Aeronautics 2024年第9期37卷 475-489页

作者： Haoyang LI Liqiang GAO Lin QI Yajing FENG Jingyu WANG Yulong LI Qifeng YU School of Aeronautics.Nort/western Polytechnical University Xiana 710072China Shaanxi Key Laboratory of Impact Dynamics and Engineering Applications Northwestern Polytechnical UniversityXian 710072 China School of Civil Aviation Northwestern Polytechnical UniversitySuzhou 215699China NPU Yangzi River Delta research institute Suzhou 215400China

The dynamic failure behavior of CoCrFeNi High-Entropy Alloy(HEA)under plane biaxial stress was investigated in *** dynamic biaxial tensile tests were conducted using an Electromagnetic Biaxial Split Hopkinson Tensile Bar(EBSHTB)*** comparison,the quasi-static uniaxial and biaxial tensile tests,as well as dynamic uniaxial tensile tests,were per-formed respectively.A cruciform specimen suitable for large plastic deformation was designed and employed in the *** Finite Element Method(FEM)verified that the improved cruciform specimen could satisfy the basic *** feasibility of the proposed specimen was further confirmed through loading ***,the quasi-static and dynamic yield loci of the HEA in the first quadrant of the principal stress space were *** results indicate that the alloy exhibits obvious strain hardening effect and strain rate strengthening effect,the yield locus and plastic work contours can be accurately described by Hill'48 criterion.

关键词： High-entropy alloys Biaxial tensile test Cruciform specimen Electromagnetic split Hop-kinson bar Digital image correlation

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Loading capacity and emulsification phenomena of HREE extraction by dialkylphosphinic acids with different β,γ,δ-substituents

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Journal of Rare Earths 2024年第1期42卷 191-199,I0007页

作者： Junlian Wang Guodong Xu Wen Xu Jianguo Cui Yufu Chen Ziyong Chang School of Civil and Resource Engineering University of Science and Technology BeijingBeijing100083China Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mines Beijing100083China State Key Laboratory of Baiyunobo Rare Earth Resource researches and Comprehensive Utilization Baotou Research Institute of Rare EarthsBaotou014030China

The relationship between dialkylphosphinic acid structure and their loading capacity for HREEs and emulsification phenomena has rarely been *** this paper,we took Lu extraction as an example to study the effect of β,γ,δ-substituents of dialkylphosphinic acids on their loading capacity and anti-emulsification performance for *** discuss conveniently,the dialkylphosphinic acids were classified into two groups:β-substituent group(P208,INET-1,P218,USTB-1 and P227)and γ,δ-substituent group(P218,P2132 and Cyanex 272).For β-substituent group extractants,their loading capacities are in the order P208(299.7 mg/L)≈INET-1(299.5 mg/L)>P218(270.8 mg/L)>>USTB-1(163.1 mg/L)>P227(151.4 mg/L),while their anti-emulsification/gelation performances are just in the opposite order P227>USTB-1>P218>P208≈INET-1 under the studied *** γ,δ-substituent group extractants,their loading capacities are in the order P218(270.8 mg/L)>P2132(192.3 mg/L)>Cyanex272(131.7 mg/L),while the anti-emulsification performance of P218 is better than those of P2132 and Cyanex *** loading capacity data given in the parentheses are obtained through repeatedly extracting Lu from ~4×10^(-4)mol/L of Lu aqueous feed solution with initial pH of 2.40 by 0.01 mol/L extractant at phase ratio A/O of 1:1.

关键词： Heavy rare earth element Dialkylphosphinic acid Extraction Loading capacity Emulsification

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Mechanical robust and self-healing flexible perovskite solar cells with efficiency exceeding 23%

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Science China Chemistry 2024年第8期67卷 2670-2678页

作者： Yaohua Wang Ruikun Cao Yuanyuan Meng Bin Han Ruijia Tian Xiaoyi Lu Zhenhua Song Shuncheng Yang Congda Lu Chang Liu Ziyi Ge College of Mechanical Engineering Zhejiang University of TechnologyHangzhou 310014China Zhejiang Provincial Engineering research Center of Energy Optoelectronic Materials and Devices Ningbo Institute of Materials TechnologyEngineeringChinese Academy of SciencesNingbo 315201China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049China

Flexible perovskite solar cells(f-PSCs) have experienced rapid advancements due to the light-weight, flexibility, and solution processability of the perovskite materials, which prompted the power conversion efficiency(PCE) to 24.08%. However, f-PSCs still face challenges in terms of mechanical and environmental stability. This is primarily due to their inherent brittleness, the presence of residual tensile strain, and the high density of defects along the boundaries of perovskite grains. To this end, we carefully developed a cross-linkable elastomers 3-[(3-acrylamidopropyl)dimethylammonium] propanoate(ADP) with electrostatic dynamic bond, which could be in-situ cross-linked and coordinate with [Pb I6]4-to regulate the crystallization process of perovskite. The cross-linked elastomers attached to the perovskite grain boundaries could release the remaining tensile strains and mechanical stresses, leading to enhanced stability and flexibility of the f-PSCs. More importantly, the electrostatic interaction between positive and negative groups of cross-linked elastomers and hydrogen bond formation between N–H and C=O accelerate the cross-linking of ADP, endowing the flexible perovskite films with self-healing ability under mild treating conditions(60 °C for 30 min). As a result, the device achieves a remarkable PCE of 23.53%(certified 23.16%). Additionally, the device exhibits impressive mechanical sustainability and durability, retaining over 90% of initial PCE even after undergoing8,000 bending cycles.

关键词： Mechanical robust and self-healing flexible perovskite solar cells with efficiency exceeding 23

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A high Li-ion diffusion kinetics in multidimensional and compact-structured electrodes via vacuum filtration casting

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Journal of Energy Chemistry 2024年第6期93卷 368-376,I0010页

作者： Jieqiong Li Ting Ouyang Lu Liu Shu Jiang Yongchao Huang M.-Sadeeq Balogun College of Materials Science and Engineering Hunan Joint International Laboratory of Advanced Materials and Technology for Clean EnergyHunan UniversityChangsha 410082HunanChina institute of Environmental research at Greater Bay Key Laboratory for Water Quality and Conservation of the Pearl River DeltaMinistry of EducationGuangzhou UniversityGuangzhou 510006GuangdongChina

Manufacturing process,diffusion co-efficient and areal capacity are the three main criteria for regulating thick electrodes for lithium-ion batteries(LIBs).However,simultaneously regulating these criteria for LIBs is desirable but remains a significant *** this work,niobium pentoxide(Nb_(2)O_(5))anode and lithium iron phosphate(LiFePO_(4))cathode materials were chosen as the model materials and demonstrate that these three parameters can be simultaneously modulated by incorporation of micro-carbon fibers(MCF)and carbon nanotubes(CNT)with both Nb_(2)O_(5) and LFP via vacuum filtration *** as-prepared MNC-20 anode and MLC-20 cathode achieves high reversible areal capacity of≈5.4 m A h cm^(-2)@0.1 C and outstanding Li-ion diffusion coefficients of≈10~(-8)cm~2 s~(-1)in the half-cell *** assembled MNC-20‖MLC-20 full cell LIB delivers maximum energy and power densities of244.04 W h kg^(-1)and 108.86 W kg^(-1),*** excellent electrochemical properties of the asprepared thick electrodes can be attributed to the highly conductive,mechanical compactness and multidimensional mutual effects of the MCF,CNT and active materials that facilitates rapid Li-ion diffusion ***,electrochemical impedance spectroscopy(EIS),symmetric cells analysis,and insitu Raman techniques clearly validates the enhanced Li-ion diffusion kinetics in the present architecture.

关键词： Thick electrodes Carbon nanotubes Li-ion diffusion co-efficient Vacuum filtration technique High areal capacity Lithium-ion batteries

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