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Underground Space 2024年第6期19卷 26-46页

作者： Yiwei liu Quansheng liu Zhijun Wu Shimin liu Yong Kang Xuhai Tang School of Civil Engineering Wuhan UniversityWuhan 430072China Department of Energy and Mineral Engineering G3 Center and EMS Energy InstituteThe Pennsylvania State UniversityUniversity ParkPA 16802USA School of Power and Mechanical Engineering Wuhan UniversityWuhan 430072China

Mechanical softening behaviors of shale in CO_(2)-water–rock interaction are critical for shale gas exploitation and CO_(2)*** work investigated the cross-scale mechanical softening of shale triggered by CO_(2)-water–rock ***,the mechanical softening of shale following 30 d of exposure to CO_(2)and water was assessed at the rock-forming mineral scale using *** mechanical alterations of rock-forming minerals,including quartz,muscovite,chlorite,and kaolinite,were analyzed and ***,an accurate grain-based modeling(AGBM)was proposed to upscale the nanoindentation *** models were generated based on the real microstructure of shale derived from TESCAN integrated minerals analyzer(TIMA)digital *** parameters of shale minerals determined by nanoindentation served as input material properties for ***,numerical simulations of uniaxial compression tests were conducted to investigate the impact of mineral softening on the macroscopic Young’s modulus and uniaxial compressive strength(UCS)of *** results present direct evidence of shale mineral softening during CO_(2)-water–rock interaction and explore its influence on the upscale mechanical properties of *** paper offers a microscopic perspective for comprehending CO_(2)-water-shale interactions and contributes to the development of a cross-scale mechanical model for shale.

关键词： Shale Cross-scale modeling Nanoindentation CO_(2)-water-rock interaction Mechanical softening

Modulation mechanism of electron energy dissipation on superlubricity based on fluorinated 2D ZIFs

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Nano Research 2024年第4期17卷 3198-3209页

作者： Yuxin Li Lei liu Kunpeng Wang Yuhong liu State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China School of Mechatronic Engineering Shanghai UniversityShanghai 200444China

Electron energy dissipation is an important energy dissipation pathway that cannot be ignored in friction ***-dimensional zeolite imidazole frameworks(2D ZIFs)and fluorine doping strategies give 2D Zn-ZIF and 2D Co-ZIF unique electrical properties,making them ideal materials for studying electron energy dissipation *** this paper,based on the superlubricity modulation of 2D fluoridated ZIFs,the optimal tribological properties are obtained on the 2D F-Co-ZIF surface,with the friction coefficient as low as *** experiments,density functional theory(DFT)simulation,and fluorescence detection are used to explain the mechanism of fluorine doping regulation of tribological properties from the two stages,namely energy transfer and energy ***,the energy will transfer into the friction system through the generation of electron–hole pairs under an external excitation,and release by radiation and non-radiation energy dissipation *** reduces energy transfer by altering the electronic properties and band structures of ZIFs,and slows down the charge transfer by enhancing the shielding efficiency,thus slowing the non-radiative energy dissipation rate during the energy release *** insights not only help us better understand the role of fluorine doping in improving tribological properties,but also provide a new way to further explore the electron energy dissipation pathway during friction.

关键词： superlubricity electron energy dissipation modulation two-dimensional zeolite imidazole frameworks(2D ZIFs) fluorination

Performance analysis and multi-objective optimization based on a modified irreversible Stirling cycle

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Science China(Technological Sciences) 2024年第6期67卷 1668-1684页

作者： XU Lei YU MinJie liu ZhiChun liu Wei School of Energy and Power Engineering Huazhong University of Science and TechnologyWuhan430074China

The efficiency of the actual Stirling engine is much lower than the ideal Carnot cycle *** obtain more precise efficiency for Stirling engines,this paper proposes a modified Stirling cycle with a more accurate heat transfer process in Stirling engines based on a thermodynamic function called available *** finite-time thermodynamic method is used to analyze the model performance under constant heat source temperature,finite temperature difference heat transfer,and incomplete regenerative processes.A new polytropic process is introduced to model the heat transfer between the working fluid and external heat sources in which only heat above ambient temperature is converted into technical *** regenerator is divided into numerous smaller heat reservoirs with individual temperature to analyze the incomplete regenerative *** expressions of the output power and thermal efficiency are obtained based on the modified irreversible Stirling cycle,and the effects of irreversible losses are analyzed to evaluate the performance of the proposed *** indicate that the efficiency of the modified cycle is much lower than that of the ideal Stirling cycle with an isothermal *** the increase of the average heat transfer temperature difference,there exists an optimum value for the power of the irreversible *** optimum power of the model was obtained for varying thermodynamic parameters by optimizing the average heat transfer temperature difference between the hot and cold *** optimize the irreversible model,the multi-objective optimization analysis is carried out based on NSGA-Ⅱ,which results in an optimized output power of 40.87 kW and an optimized thermal efficiency of 44%.

关键词： stirling cycle regenerative processes isopotential processes multi-objective optimization finite time thermodynamics

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双级加速离子光学系统几何参数研究

激光与光电子学进展 2017年第4期54卷 196-203页

作者：贾连军张天平陈娟娟贾艳辉刘明正兰州空间技术物理研究所真空技术与物理重点实验室甘肃兰州730000

针对双级加速离子光学系统的设计,开展了栅极几何参数对离子光学系统性能影响的研究。采用质点网格法和蒙特卡罗碰撞法开展栅极关键几何参数对束流引出能力、束流发散角、交换电荷(CEX)离子的截获影响规律研究;另外,还开展了不同比冲下... 详细信息

针对双级加速离子光学系统的设计,开展了栅极几何参数对离子光学系统性能影响的研究。采用质点网格法和蒙特卡罗碰撞法开展栅极关键几何参数对束流引出能力、束流发散角、交换电荷(CEX)离子的截获影响规律研究;另外,还开展了不同比冲下束流发散角、碰撞交换电荷离子的变化趋势研究。研究结果表明,屏栅孔径对束流引出能力、束流发散角、CEX离子截获电流以及鞍点电势都有影响,随着屏栅孔径的增加,束流引出能力、束流发散角和鞍点电势呈上升趋势。加速栅孔径的变化对CEX离子得能量分布有影响,随着加速栅孔径的增大,截获的高能CEX离子逐渐减少,而随着加速栅厚度的增加,束流发散角、CEX离子的截获数量和能量呈上升趋势。在8000s比冲下,加速级间距的改变对束流引出能力影响较小。另外,比冲对离子光学系统性能也有影响,比冲越高,束流发散角越小,且加速栅截获的CEX离子也越少。

关键词：测量离子推力器双级加速离子光学系统质点网格法和蒙特卡罗碰撞法交换电荷离子数值模拟

Design and synthesis of thiol-terminated imidothioether oligomer as thermally latent hardener and modifier for high-performance epoxy/thiol thermosets

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Science China Chemistry 2024年第2期67卷 632-641页

作者： Xing liu Jianjun Zhou Shumei liu Jianqing Zhao School of Materials Science and Engineering South China University of TechnologyGuangzhou510640China Key Lab Guangdong High Property&Functional Polymer Materials Key Laboratory of Polymer Processing EngineeringMinistry of EducationGuangzhou510640China

Conventional base-catalyzed epoxy/aliphatic thiol systems have a poor storage stability,and are impossible to be one-pot systems.A widely accepted solution is to use the latent catalysts,which are usually insoluble anionic initiators sensitive to impurities and moisture,and have many limitations in practical *** this work,a soluble thiol-terminated imidothioether oligomer(TPI) was synthesized and used as a latent hardener and modifier to prepare one-pot epoxy/thiol systems without the latent *** latent behavior and curing mechanism of epoxy systems(EP/TPI series),consisted of bisphenol A diglycidyl ether(DGEBA),pentaerythritol tetrakis(mercaptoacetate)(PETMP) and TPI,were *** thiol exchange reaction between TPI and PETMP preceded the curing reaction of DGEBA,and produced aromatic thiols,which were unreactive at ambient conditions and reacted with DGEBA to form the thermosets at temperatures above 130 ℃.At the loading of 24.4 wt%TPI,the epoxy system(EP/TPI-3) had a shelf life of 13 days and was completely cured within 20 min at 180 ℃.Meanwhile,the catalyst-free curing process of EP/TPI-3 system was insensitive to impurities and ***,the thermal and mechanical properties of EP/TPI-3 thermoset were simultaneously improved,thereinto,the glass transition temperature,Young's modulus and ultimate tensile strength were increased by 16.7 ℃,12.9%,and 13.6%,respectively,compared with those of the commercial DGEBA/PETMP *** work shows that TPI has the potential to be a powerful alternative to commercial latent catalysts,and EP/TPI thermosets with high performance have broad application prospects.

关键词： thiol-terminated imidothioether oligomer epoxy systems thiol exchange reaction thermal latency high performance

How to Construct a Lower Risk FOF Based on Correlation Network? The Method of Principal Component Risk Parity Asset Allocation

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Journal of Systems Science & Complexity 2024年第3期37卷 1052-1079页

作者： BAI Wei ZHANG Junting liu Haifei liu Kai School of Management and Engineering Nanjing UniversityNanjing 210093China Postdoctoral Workstation of Bank of Jiangsu Co. LtdNanjing 210006China College of Finance Nanjing Agricultural UniversityNanjing 210095China University of Prince Edward Island 550 University AveCharlottetownPE C1A4P3Canada

In order to build a low-risk Fund of Funds(FOF), from the perspective of correlation, the principal component factor is used to improve the traditional risk parity model. Principal component analysis is used to decompose the underlying assets and generate unrelated principal component factors,and then the authors can construct a principal component risk parity portfolio. The proposed empirical results based on China’s mutual fund market show that the performance of principal component risk parity portfolio(PCRPP) is better than that of equal weight portfolio(EWP) and traditional risk parity portfolio(RPP). That is to say, not only the PCRPP in this paper has much lower risk than EWP and RPP, but also slightly better than EWP and RPP in terms of average return. Moreover, the study of dividing the underlying assets shows that the PCRPP in this paper is not sensitive to the underlying assets. The PCRPP in this paper is better than EWP and RPP for both the better performing funds and the worse performing funds. In addition, the empirical results on dynamic portfolio adjustments show that it is not appropriate to adjust asset allocation too frequently when the expected rate of return is calculated using the arithmetic mean.

关键词： Fund of funds(FOF) mutual funds portfolio risk principal component analysis risk parity portfolio

Lanthanide-based microlasers:Synthesis,structures,and biomedical applications

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Nano Research 2024年第1期17卷 97-111页

作者： Qian Zhang Yawei liu Kai liu Hongjie Zhang Engineering Research Center of Advanced Rare Earth Materials(Ministry of Education) Department of ChemistryTsinghua UniversityBeijing 100084China State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Xiangfu Laboratory Jiaxing 314102China

The large size of lasers limits their applications in confined spaces,such as in biosensing and in vivo brain tissue *** this regard,micron-sized lasers have been *** exhibit great potential for biological detecting,remote sensing,and depth tracking due to their small sizes,sensitive properties of their spectral fingerprints,and flexible positional modulation in the ***-based luminescent materials that possess long excited-state lifetime,narrow emission bandwidth,and upconversion behaviors are promising as gain mediums for novel *** addition,lanthanide-based microlasers could be generated under natural ambient conditions with pumped or continuous light sources,which significantly promotes the practical applications of *** progress in the design,synthesis,and biomedical applications of lanthanide-based microlasers has been outlined in this *** ions doped and upconverted lanthanide-based microlasers are highlighted,which exhibit advantageous structures,miniaturized dimensions,and high lasing *** applications of lanthanide-based microlasers are further discussed,the upconverted microlasers show great advantages for biological applications owing to their tunable excitation and emission characteristics and excellent environmental ***,perspectives and challenges in the field of lanthanide-based microlasers are presented.

关键词： microlasers lanthanide-based luminescent materials upconversion nanoparticles biological applications

A combinatorial synthesis method for identification of orally bioavailable cyclic peptide

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Science China Chemistry 2024年第8期67卷 2429-2430页

作者： Zhenzhen liu Li liu Bo Tang College of Chemistry Chemical Engineering and Materials ScienceKey Laboratory of Molecular and Nano ProbesMinistry of EducationCollaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of ShandongInstitutes of Biomedical SciencesShandong Normal UniversityJinan 250014China Laoshan Laboratory Qingdao 266237China

Cyclic peptides are a type of polypeptide with macrocyclic structure formed by canonical and non-canonical amino *** to their rigid conformation and large surface area,cyclic peptides typically exhibit high binding affinity and specificity with target proteins,particularly those considered undruggable by traditional small molecule drugs,such as protein-protein interactions[1].Additionally,they are convenient to be chemical modified to improve the pharmacological or pharmacokinetic properties.

关键词： properties. canonical synthesis

Lattice Boltzmann simulation study of anode degradation in solid oxide fuel cells during the initial aging process

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International Journal of Minerals,Metallurgy and Materials 2024年第2期31卷 405-411页

作者： Shixue liu Zhijing liu Shuxing Zhang Hao Wu Hydrogen Energy Industrial Technology Innovation Center China Nuclear Power Technology Research InstituteShenzhen 518031China Shenzhen Engineering Research Center for Hydrogen Safety Shenzhen 518031China

For present solid oxide fuel cells(SOFCs),rapid performance degradation is observed in the initial aging process,and the dis-cussion of the degradation mechanism necessitates quantitative ***,focused ion beam-scanning electron microscopy was em-ployed to characterize and reconstruct the ceramic microstructures of SOFC *** lattice Boltzmann method(LBM)simulation of multiphysical and electrochemical processes in the reconstructed models was *** samples collected from industrial-size cells were characterized,including a reduced reference cell and a cell with an initial aging *** parameters of the reconstructed microstructures revealed a significant decrease in the active triple-phase boundary and Ni connectivity in the aged cell compared with the reference *** LBM simulation revealed that activity degradation is dominant compared with microstructural degradation during the initial aging process,and the electrochemical reactions spread to the support layer in the aged *** microstructural and activity de-gradations are attributed to Ni migration and coarsening.

关键词： solid oxide fuel cell anode degradation focused ion beam-scanning electron microscopy lattice Boltzmann method

Enlarged interlayer of separator coating enabling high-performance lithiumsulfur batteries

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Frontiers of Chemical Science and Engineering 2024年第2期18卷 103-112页

作者： Yanqi Feng Hui liu Xiaoting liu Qiongqiong Lu School of Materials&Environment Engineering Chengdu Technological UniversityChengdu 611730China School of Materials Science and Engineering Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic MaterialsShaanxi University of Science and TechnologyXi’an 710021China Green Catalysis Center and College of ChemistryZhengzhou UniversityZhengzhou 450001China Institute of Materials Henan Key Laboratory of Advanced Conductor MaterialsHenan Academy of SciencesZhengzhou 450046China Leibniz Institute for Solid State and Materials Research(IFW) Dresden e.V.Dresden 01069Germany

Lithiumsulfur batteries have been intensively studied due to their high theoretical energy density and abundant sulfur resources. However, their commercial application is hindered by the low redox kinetics and high sulfur losses. In principle, in the design of cathodes and separators, the adsorption toward lithium-polysulfides should be enhanced and the conversion of soluble high-order lithium-polysulfides should be catalyzed. Herein, a KV_(3)O_(8)·0.75H_(2)O separator is designed as an effective lithium-polysulfides mediator in lithiumsulfur batteries. The intercalated K+ would enlarge the interlayer spacing of vanadium oxides, preventing the collapse of the layer structure and improving the electrical/ion conductivity of the interface. Moreover, the KV_(3)O_(8)·0.75H_(2)O modified separator possess a prior adsorption and high redox kinetics toward lithium-polysulfides due to the enhanced diffusion kinetics, which guarantees the high-rate capability and efficient utilization of sulfur. As a result, lithiumsulfur batteries exhibit a high capacity of 1362 mAh·g^(-1) and a long lifespan with a low capacity loss of 0.073% per cycle. This work may provide an alternative way to establish a functional separator to balance the adsorption and conversion of polysulfides during the redox back and forth.

关键词： lithium kinetics adsorption