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Resolving aging dynamics of a 3D colloidal glass

Science China(Physics,mechanics & Astronomy) 2024年第3期67卷 110-118页

作者： XiaoJuan Wang Jun Duan Gan Ding YunZhuo Lu Xing Lu LanHong Dai MinQiang Jiang State Key laboratory of Nonlinear mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of materials Science and Engineering Dalian Jiaotong UniversityDalian 116028China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

Physical aging is an inherent property of glassy matter, but understanding its microscopic mechanism remains a challenge particularly at the particle level. In this work, we use a confocal microscope to in-situ trace the particle trajectories in a 3D colloidal glass for 73000 s, aiming at resolving the aging dynamics. By calculating the mean square displacement of particle motions, we find that the glass aging with time can be divided into three stages: β relaxation, α relaxation and free diffusion. The system's mean square displacement at each aging state is quantitatively resolved into three contributions of particle dynamics modes: vibration within the nearest-neighbor cages, hopping between cages and cooperative rearrangement. We further calculate the particle's free volume and find that the β-to-α transition is accompanied by the temporary increase of the system-averaged free volume due to pronounced hops of particles. Nevertheless, the temporal autocorrelation of the free volume spatial distribution still obeys a monotonically stretched exponential decay with an exponent of 0.76, which is related to the sub-diffusion dynamics of cooperative rearrangements and hops mixed in α relaxation. According to the resolved vibrational displacements,we calculate the vibrational density of states of this 3D glass, and the characteristic boson peak is reproduced at low *** findings shed insight into the particle-level aging dynamics of a real glass under purely thermal activation.

关键词： colloidal glass physical aging particle dynamics free volume boson peak

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Closed-Form Solution for a Circular Nanohole with Surface Effects Under Uniform Heat Flux

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Acta Mechanica Solida Sinica 2024年第1期37卷 43-52页

作者： Jieyao Tang Jieyan Zhao Haibing Yang Cunfa Gao State Key laboratory of mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China School of Civil Engineering and Transportation South China University of TechnologyGuangzhou 510641China College of mechanics and materials Hohai UniversityNanjing 211100China

This paper investigates the steady-state thermoelastic problem of a circular nanohole embedded in an infinitely large elastic plane subjected to a uniform far-field heat flux.A lowly conductive surface model is used to account for the effects of surface phonon scattering,while the complete Gurtin–Murdoch model is utilized to characterize the effects of surface tension and surface *** closed-form solution to the temperature and stress field surrounding the hole is derived in the context of complex variable *** numerical examples are presented to analyze the influence of surface effects on thermal stress *** is shown that surface effects induce notable increases in normal and shear stresses around the ***,all three stress components(hoop,normal,and shear)in the vicinity of the hole exhibit substantial augmentation with increasing surface tension and surface *** particular,it is found that the presence of surface effects amplifies the variation in stress gradients and intensifies stress concentration around the hole.

关键词： Circular nanohole Surface effect Thermal stress Heat flux

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轻质层对提高陶瓷复合装甲弹道阻力影响的理论与数值分析

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Acta Mechanica Sinica 2024年第3期40卷 1-9页

作者：杨尚霖王毅刚张逸之柳占立 applied mechanics laboratory Department of Engineering MechanicsSchool of Aerospace EngineeringTsinghua UniversityBeijing100084China

陶瓷复合装甲主要由陶瓷层和背板层组成,广泛应用于冲击防护.然而,目前仍缺乏背板层在提高陶瓷复合装甲系统防弹性能方面的定量认识和分析.本文以B4C/UHMWPE双层装甲体系为例,从理论上系统地研究了UHMWPE层在提高陶瓷复合装甲弹道阻力... 详细信息

陶瓷复合装甲主要由陶瓷层和背板层组成,广泛应用于冲击防护.然而,目前仍缺乏背板层在提高陶瓷复合装甲系统防弹性能方面的定量认识和分析.本文以B4C/UHMWPE双层装甲体系为例,从理论上系统地研究了UHMWPE层在提高陶瓷复合装甲弹道阻力方面的增强机理和适合UHMWPE厚度的选取.开发并验证了预测双层装甲系统剩余速度的理论模型.具体而言,分别从理论上获得与塑性、断裂和摩擦相关的耗散能以及由弹性应变能和动能组成的储存能.理论结果表明,随着UHMWPE层厚度的增加,耗散能单调增加,而储存能则先增加后减少,并会出现一个转折点,这是由于储存能的主导机制由系统固有的最大储存能转变为剩余动能.此外,对于给定的弹道阻力,根据存储能的转变提出了为降低面密度的最佳UHMWPE厚度的参考值,这与陶瓷厚度、冲击速度和弹丸质量有关.本文的研究有助于指导陶瓷复合装甲的轻量化设计.

关键词： Ballistic resistance Bi-layer armor Theoretical analysis Optimal UHMWPE thickness

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Waste acid recovery utilizing monovalent cation permselective membranes through selective electrodialysis

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Chinese Journal of Chemical Engineering 2024年第7期71卷 45-57页

作者： Yanran Zhu Yue Zhou Qian Chen Rongqiang Fu Zhaoming Liu Liang Ge Tongwen Xu Anhui Provincial Engineering laboratory of Functional Membrane materials and Technology Department of Applied ChemistrySchool of Chemistry and Materials ScienceUniversity of Science and Technology of ChinaHefei 230026China Key laboratory of Charged Polymeric Membrane materials of Shandong Province Shandong Tianwei Membrane Technology Co.Ltd.Weifang 261000China

Selective electrodialysis(SED)has surfaced as a highly promising membrane separation technique in the realm of acid recovery owing to its ability to effectively separate monovalent ions through the utilization of a potential ***,the current SED process is limited by conventional commercial monovalent cation permselective membranes(MCPMs).This study systematically investigates the use of an independently developed MCPM in the SED process for acid *** factors such as current density,volume ratio,initial ion concentration,and waste acid systems are *** independently developed MCPM offers several advantages over the commercial monovalent selective cation-exchange membrane(CIMS),including higher recovered acid concentration,better ion flux ratio,improved acid recovery efficiency,increased recovered acid purity,and higher current *** SED process with the MCPM achieves a recovered acid of 95.9%and a concentration of 2.3 mol·L^(–1) in the HCl/FeCl_(2) system,when a current density of 20 mA·cm^(-2) and a volume ratio of 1:2 are ***,in the H_(2)SO_(4)/FeSO_(4) system,a purity of over 99%and a concentration of 2.1 mol·L^(–1) can be achieved in the recovered *** study thoroughly examines the impact of operation conditions on acid recovery performance in the SED *** independently developed MCPM demonstrates outstanding acid recovery performance,highlighting its potential for future commercial utilization.

关键词： Selective electrodialysis Wastewater Monovalent cation permselective membranes Separation Recovery

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Dynamic response of sandwich panel attached with a double mass-spring-damping system to shallow-buried explosion:Analytical modeling

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Science China(Technological Sciences) 2024年第2期67卷 568-586页

作者： ZHANG DuJiang ZHAO ZhenYu GAO HuiYao LU TianJian State Key laboratory of mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China MIIT Key laboratory of Multifunctional Lightweight materials and Structures(MLMS) Nanjing University of Aeronautics and AstronauticsNanjing 210016China

How to ensure the safety of occupants has become a challenge for protective design of armored vehicles against intensive blast *** this study,for armored vehicles subjected to shallow-buried explosions,an analytical model was established to characterize the dynamic performance of an all-metallic sandwich floorboard attached with a double mass-spring-damping system(mimicking seat and occupant),with the former consisting of a front face,a core and a rear *** validation,numerical simulations with the method of finite elements(FE)were *** agreement between analytical predictions and numerical results was *** analytical model was then employed to quantify the effects of explosive mass,yield stress of material make,configurational parameters of sandwich panel,spring stiffness,and damping coefficient on dynamic response of the sandwich panel and double mass-spring-damping *** increasing explosive mass and decreasing yield stress of material make,the peak displacements of rear face,seat and occupant were all found to *** core relative density was increased,these peak displacements also increased when the ratio of face thickness to core height was relatively *** the ratio of face thickness to core height led to increased peak accelerations of seat and *** peak displacement of rear face was insensitive to the increase of either spring stiffness or damping coefficient,while the peak acceleration of occupant increased with increasing spring *** increasing the damping coefficient between the rear face and seat or that between the seat and occupant or both,the peak acceleration of occupant *** occupant safety duly considered,the proposed analytical model provides useful guidance for designing high-performance protective structures for armored vehicles subjected to intensive blast loadings.

关键词： analytical model shallow-buried explosion sandwich panel occupant safety mass-spring-damping system

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Analysis of natural vibration of truncated conical shells partially filled with fluid

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International Journal of Mechanical System Dynamics 2024年第2期4卷 142-152页

作者： Sergey A.Bochkarev Sergey V.Lekomtsev laboratory of Functional materials Institute of Continuous Media MechanicsUral Branch of Russian Academy of SciencesPermRussian Federation

In this paper,we study the vibrational behavior of shells in the form of truncated cones containing an ideal compressible *** sloshing effect on the free surface of the fluid is *** dynamic behavior of the elastic structure is investigated based on the classical shell theory,the constitutive relations of which represent a system of ordinary differential equations written for new *** fluid vibrations are described in terms of acoustic approximation using the wave equation for hydrodynamic pressure written in spherical *** transformation into the system of ordinary differential equations is carried out by applying the generalized differential quadrature *** formulated boundary value problem is solved by Godunov's orthogonal sweep *** frequencies of shell vibrations are calculated using the stepwise procedure and the Muller *** accuracy and reliability of the obtained results are estimated by making a comparison with the known numerical and analytical *** dependencies of the lowest frequency on the fluid level and cone angle of shells under different combinations of boundary conditions(simply supported,rigidly clamped,and cantilevered shells)have been studied *** conical straight and inverted shells,a numerical analysis has been performed to estimate the possibility of finding configurations at which the lowest natural frequencies exceed the corresponding values of the equivalent cylindrical shell.

关键词： classical shell theory conical shell Godunov's orthogonal sweep method ideal compressible fluid generalized differential quadrature method natural vibrations

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Unravelling the anisotropic light-matter interaction in strainengineered trihalide MoCl_(3)

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Nano Research 2024年第4期17卷 2981-2987页

作者： Yuxuan Sun Ziang Liu Zeya Li Feng Qin Junwei Huang Caiyu Qiu Hongtao Yuan National laboratory of Solid State Microstructures Jiangsu Key Laboratory of Artificial Functional MaterialsCollege of Engineering and Applied Sciencesand Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210000China

Layered trihalides exhibit distinctive band structures and physical properties due to the sixfold coordinated 3d or 4d transition metal site and partially occupied d orbitals,holding great potential in condensed matter physics and advanced electronic *** research focused on trihalides with highly symmetric honeycomb-like structures,such as CrI3 andα-RuCl_(3),while the role of crystal anisotropy in trihalides remains *** particular,the trihalide MoCl_(3) manifests strong in-plane crystal anisotropy with the largest difference in Mo–Mo interatomic *** on such material is imperative to address the lack of investigations on the effect of anisotropy on the properties of ***,we demonstrated the anisotropy of MoCl_(3) through polarized Raman spectroscopy and further tuned the phonon frequency via strain *** showed the Raman intensity exhibits twofold symmetry under parallel configuration and fourfold symmetry under perpendicular configuration with changing the polarization angle of incident ***,we found that the phonon frequencies of MoCl_(3) decrease gradually and linearly with applying uniaxial tensile strain along the axis of symmetry in the MoCl_(3) crystal,while those frequencies increase with uniaxial tensile strain applied *** results shed light on the manipulation of anisotropic light-matter interactions via strain engineering,and lay a foundation for further exploration of the anisotropy of trihalides and the modulation of their electronic,optical,and magnetic properties.

关键词： layered trihalide MoCl_(3) polarized Raman spectroscopy strain engineering anisotropy

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Highly elastic 2D covalent organic framework films of interwoven single crystals

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National Science Review 2024年第7期11卷 71-72页

作者： Tongwen Xu Key laboratory of Precision and Intelligent Chemistry Department of Applied ChemistrySchool of Chemistry and Materials ScienceUniversity of Science and Technology of China

Two-dimensional(2D) materials feature angstrom-scale pores and tunable pore chemistry, demonstrating great potential for applications including flexible electronics and *** ion/molecule transport in the sub-nanometer-sized pore confinement often reveals phenomena not seen in bulk materials [1]. Yet, the practical application of 2D materials is hindered by their poor mechanical properties.

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Wearable ultrasensitive and rapid human physiological monitoring based on microfiber Sagnac interferometer

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Science China(Information Sciences) 2024年第3期67卷 281-290页

作者： Xin WANG Hongyou ZHOU Meihua CHEN Yongcheng HE Zhishen ZHANG Jiulin GAN Zhongmin YANG State Key laboratory Luminescent materials and Devices Institute of Optical Communication MaterialsSpecial Glass Fiber and Device Engineering Technology Research and Development Center of Guangdong ProvinceGuangdong Provincial Key Laboratory of Fiber Laser Materials and Applied TechniquesSouth China University of Technology Guangdong-Hong Kong-Macao Joint laboratory for Intelligent Micro-Nano Optoelectronic Technology Foshan University

High-sensitive and fast-responding flexible strain sensors are essential for the smart wearable devices that precisely and dynamically perceive the weak deformations induced by human physiological signals. Here, a flexible strain sensor via polydimethylsiloxane(PDMS)-encapsulated microfiber Sagnac interferometer was designed and prepared for monitoring the human pulse signals and sound vibrations. The sensor achieved a record-breaking sensitivity(gauge factor, GF = 9977) and an extremely low detection limit(0.00025%) due to the strong polarization-dependent coupling effect in the microfiber coupler and the polarization-mixing effect in the Sagnac loop. The relative intensity demodulation method also enabled a fast response time of 10 μs. The wearable pulse measurements were implemented by attaching this flexible strain sensor directly to human skin at various locations and the waveform details were accurately captured. Taking advantage of the ultra-high sensitivity and fast response performance of the prepared sensor, the real-time dynamic acquisition of the underwater weak signal, such as the hydro-acoustic waves with a wide range of 20 Hz–16.86 k Hz, has been demonstrated. These initial results pave the way for a new and innovative category of underwater wearable devices with rapid detection of human physiological signals and weak environmental vibrations.

关键词： flexible strain sensor microfiber Sagnac interferometer underwater detection

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Magnetic behaviors and magnetocaloric effects in rare earth high-entropy amorphous/nanocrystalline alloys

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Journal of Rare Earths 2024年第1期42卷 129-136,I0005页

作者： Lin Xue Liliang Shao Baosen Zhang Zongzhen Li Jiangbo Cheng Baolong Shen College of mechanics and materials Hohai UniversityNanjing211106China School of materials Science and Engineering Jiangsu Key Laboratory of Advanced Metallic MaterialsSoutheast UniversityNanjing211189China School of materials Science and Engineering Nanjing Institute of TechnologyNanjing211167China Jiangsu JITRI Advanced Energy materials Research Institute Co. Ltd.Changzhou213000China

Rare earth high-entropy alloys(RE-HEAs)exhibit great potential to be applied as refrigerants due to their good comprehensive magnetocaloric *** this work,octary GdTbDyHoErTmCoAl and GdTbDyHoErTmCoNi RE-HEAs with amorphous/nanocrystalline structure exhibiting comparable magnetocaloric effect were *** RE-HEAs show a second-order magnetic phase transition in the temperature range of hydrogen *** to the complex magnetic interactions,a spin glasslike behavior at low temperatures is observed in the RE-HEAs.A superior magnetocaloric effect is obtained in the nanocrystalline GdTbDyHoErTmCoNi high-entropy alloy that is multiphase attributed to a stronger magnetic exchange interaction when compared with the other that exhibits single amorphous *** heterogeneous microstructure,homogeneous chemical distributions are observed in the partially crystallized high-entropy *** addition,the magnetocaloric effect and magnetic transition behavior of rare earth medium-and high-entropy alloys,including the RE-HEAs in this study,are summarized and *** results in this work provide a helpful guide for the design of RE-HEAs for hydrogen liquefaction applications with excellent magnetocaloric effects.

关键词： Rare earths High-entropy alloy Metallic glass Magnetocaloric effect

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