Thermal barrier coatings （TBCs） were developed to protect metallic blades and vanes working in turbo-engines. The two-layered structure TBCs, consisting of NiCoCrAlY bond coat and yttria stabilized zirconia （YSZ）,...Thermal barrier coatings （TBCs） were developed to protect metallic blades and vanes working in turbo-engines. The two-layered structure TBCs, consisting of NiCoCrAlY bond coat and yttria stabilized zirconia （YSZ）, were deposited on a cylinder of superalloy substrate by the electron beam-physical vapor deposition （EB-PVD）. The failure mechanism of the TBCs was investigated with a thermo-mechanical fatigue testing system under the service condition similar to that for turbine blades. Non-destructive evaluation of the coated specimens was conducted through the impedance spectroscopy. It is found that the crack initiation mainly takes place on the top coat at the edge of the heated zones.展开更多
Under combined electro-thermo-mechanical loadings, the nonlinear bending of piezoelectric cylindrical shell reinforced with boron nitride nanotubes (BNNTs) is investigated in this paper. By employing nonlinear strains...Under combined electro-thermo-mechanical loadings, the nonlinear bending of piezoelectric cylindrical shell reinforced with boron nitride nanotubes (BNNTs) is investigated in this paper. By employing nonlinear strains based on Donnell shell theory and utilizing piezoelectric theory including thermal effects, the constitutive relations of the piezoelectric shell reinforced with BNNTs are established. Then the governing equations of the structure are derived through variational principle and resolved by applying the finite difference method. In numerical examples, the effects of geometric nonlinear, voltage, temperature, as well as volume fraction on the deflection and bending moment of axisymmetrical piezoelectric cylindrical shell reinforced with BNNTs are discussed in detail.展开更多
Thermo-mechanical fatigue （TMF） behavior of FGH96, a nickel-base powder metallurgy superalloy, has been studied under tension-tension loading at the temperature range from 550 to 720 ℃. The results show that TMF fr...Thermo-mechanical fatigue （TMF） behavior of FGH96, a nickel-base powder metallurgy superalloy, has been studied under tension-tension loading at the temperature range from 550 to 720 ℃. The results show that TMF fracture mode is intergranular for the in-phase （IP）, but transgranular cleavage-like for the out-of-phase （OP） samples. The total content of Al, Ti and Nb in the γ＇ phases for the IP or OP samples and the partitioning ratio of γ＇/γin these elements for the IP samples are relatively higher at the lower strain amplitude, which is consistent with the case of the γ＇ size that is larger at the lower strain amplitude, the lattice parameter misfit is negative and the absolute value is lower at the lower strain amplitude that is correlative with the change of the γ＇ morphology. The deformation at the lower strain amplitude is mainly dominated by the dislocation lines and dislocation pairs in the matrix channels, at the higher strain amplitude dominated by the large numbers of superlattice stacking faults within the γ＇ phases.展开更多
Novel crystallization behaviors of Zr55Cu30Al10Ni5 bulk metallic glass are investigated. On the one hand, mixed oxides, including CuO, CuAlO2, CuA12O4 and ZrO2, show sequential oxidation process determined by coupling...Novel crystallization behaviors of Zr55Cu30Al10Ni5 bulk metallic glass are investigated. On the one hand, mixed oxides, including CuO, CuAlO2, CuA12O4 and ZrO2, show sequential oxidation process determined by coupling effects of specific cyclic load and temperature. On the other hand, at a temperature (100℃) by far lower than Tg of 412 ℃, under cyclic loading condition, non-oxidized binary alloy CuZr2 is precipitated;the thermo-mechanical coupled effects of temperature below Tg, and fatigue accumulation on the non-oxidized crystallization behaviors are revealed. Meanwhile, at a constant temperature of 400 ℃, by comparing among the XRD patterns, respectively, obtained from tensile, creep and fatigue fractures, the dominating effect of cyclic load on the generation of non-oxidized CuZr2 is verified. Furthermore, the crystallization behavior of amorphous phases under cyclic loading condition is observed through TEM micrograph and diffraction pattern at 100℃.展开更多
In the past studies, it has been discovered that the shape memory effect(SME) in the Fe-Mn-Si shape memory alloy(Fe-SMA)can gradually be enhanced by a pre-process called as shape memory training process under cyclic t...In the past studies, it has been discovered that the shape memory effect(SME) in the Fe-Mn-Si shape memory alloy(Fe-SMA)can gradually be enhanced by a pre-process called as shape memory training process under cyclic thermo-mechanical loading.On the other hand, it has been shown that the SME of Fe-SMA can also be affected by changing the strain rate. Therefore, it is possible to improve the SME by combining the strain rate sensitivity and shape memory training process. However, the improvement of SME caused by the training process under impact condition is still unclear. For the training process under impact condition, it is difficult to interrupt the test at the desired strain level due to many reflections of stress waves, which reload the specimen from the free ends. In this paper, to obtain reliable experimental results of SME after the training process under impact condition, the stress waves after first loading are eliminated by the double momentum-trap structure introduced into the impact tensile testing apparatus based on the split Hopkinson pressure bar method. In order to achieve an optimum design of the structure used in experiments, the finite element simulation of the structure is performed. Then, tensile tests in the training process of Fe-28Mn-6Si-5Cr alloy at different strain rates including the impact level are conducted and temperature change of the specimen is measured during training and heating process. As a result, the improvement of SME in the alloy after the training process under quasi-static and impact loading is compared with that under quasi-static loading through verification processes.展开更多
Geological repository of high-level nuclear waste(HLNW),the most feasible approach for the safe and permanent treatment of HLNW without human intervention,has been investigated for years by many researchers.In some co...Geological repository of high-level nuclear waste(HLNW),the most feasible approach for the safe and permanent treatment of HLNW without human intervention,has been investigated for years by many researchers.In some countries,real facilities for the geo-logical repository are already under construction.In Japan,however,due to complicated geologic conditions,especially underground water and fractured rock masses,and the high risk of natural disasters,ensuring the long-term stability of the method remains a struggle.The influential factors include underground water,heat generation from radioactive waste,and thermal and chemical weathering of the surrounding rock mass as a natural barrier.It is difficult to estimate and verify the long-term stability for up to one hundred thousand years,a complicated thermal-hydraulic-mechanical-chemical coupling behavior,via any field test.The objective of the study is to develop a numerical method for predicting the long-term stability of geological repositories.As the first step toward realizing this objec-tive,heating and loading tests on cave model made of man-made rock specimens that are composed of diatoms,gypsum,and water,which are viscoplastic materials,were conducted,based on which a newly proposed numerical method with finite element method(FEM)was used to describe the thermal,mechanical,and time-dependent behavior of the model tests for a geological repository.To ensure the accuracy of the numerical calculations,all the material parameters in the thermoelasto-viscoplastic model with consideration of overconsolidation,the structure,and the influence of intermediate stress were determined via triaxial compression/creep tests under various temperatures,confining stresses,and loading rates.Finally,the validity of the numerical method was demonstrated by model tests over a limited time span.展开更多
In rock drilling and blasting,the misfire of electronic detonators will not only affect the rock fragmentation result but also bring serious potential safety hazards to engineering construction.An accurate and compreh...In rock drilling and blasting,the misfire of electronic detonators will not only affect the rock fragmentation result but also bring serious potential safety hazards to engineering construction.An accurate and comprehensive understanding of the failure mechanisms of electronic detonators subjected to impact loading is of great significance to the reliability design and field safety use of electronic detonators.The spatial distribution characteristics and failure modes of misfired electronic detonators under different application scenarios are statistically analysed.The results show that under high impact loads,electronic detonators will experience failure phenomena such as rupture of the fuse head,fracture of the bridge wire,falling off of the solder joint,chip module damage and insufficient initiation energy after deformation.The lack of impact resistance is the primary cause of misfire of electronic detonators.Combined with the underwater impact resistance test and the impact load test in the adjacent blasthole on site,the formulas of the impact failure probability of the electronic detonator under different stress‒strength distribution curves are deduced.The test and evaluation method of the impact resistance of electronic detonators based on stress‒strength interference theory is proposed.Furthermore,the impact failure model of electronic detonators considering the strength degradation effect under repeated random loads is established.On this basis,the failure mechanism of electronic detonators under different application environments,such as open-pit blasting and underground blasting,is revealed,which provides scientific theory and methods for the reliability analysis,design and type selection of electronic detonators in rock drilling and blasting.展开更多
A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that th...A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that the loading parameters(initial normal stress,normal stiffness,and shear velocity)determine propagation paths of the wing and secondary cracks in rock bridges during the initial shear cycle,creating different morphologies of macroscopic step-path rupture surfaces and asperities on them.The differences in stress state and rupture surface induce different cyclic shear responses.It shows that high initial normal stress accelerates asperity degradation,raises shear resistance,and promotes compression of intermittent joints.In addition,high normal stiffness provides higher normal stress and shear resistance during the initial cycles and inhibits the dilation and compression of intermittent joints.High shear velocity results in a higher shear resistance,greater dilation,and greater compression.Finally,shear strength is most sensitive to initial normal stress,followed by shear velocity and normal stiffness.Moreover,average dilation angle is most sensitive to initial normal stress,followed by normal stiffness and shear velocity.During the shear cycles,frictional coefficient is affected by asperity degradation,backfilling of rock debris,and frictional area,exhibiting a non-monotonic behavior.展开更多
Non-seismically designed(NSD)beam-column joints are susceptible to joint shear failure under seismic loads.Although significant research is available on the seismic behavior of such joints of planar frames,the informa...Non-seismically designed(NSD)beam-column joints are susceptible to joint shear failure under seismic loads.Although significant research is available on the seismic behavior of such joints of planar frames,the information on the seismic behavior of joints of space frames(3D joints)is insufficient.The 3D joints are subjected to bi-directional excitation,which results in an interaction between the shear strength obtained for the joint in the two orthogonal directions separately.The bi-directional seismic behavior of corner reinforced concrete(RC)joints is the focus of this study.First,a detailed finite element(FE)model using the FE software Abaqus,is developed and validated using the test results from the literature.The validated modeling procedure is used to conduct a parametric study to investigate the influence of different parameters such as concrete strength,dimensions of main and transverse beams framing into the joint,presence or absence of a slab,axial load ratio and loading direction on the seismic behavior of joints.By subjecting the models to different combinations of loads on the beams along perpendicular directions,the interaction of the joint shear strength in two orthogonal directions is studied.The comparison of the interaction curves of the joints obtained from the numerical study with a quadratic(circular)interaction curve indicates that in a majority of cases,the quadratic interaction model can represent the strength interaction diagrams of RC beam to column connections with governing joint shear failure reasonably well.展开更多
The current single-atom catalysts(SACs)for medicine still suffer from the limited active site density.Here,we develop a synthetic method capable of increasing both the metal loading and mass-specific activity of SACs ...The current single-atom catalysts(SACs)for medicine still suffer from the limited active site density.Here,we develop a synthetic method capable of increasing both the metal loading and mass-specific activity of SACs by exchanging zinc with iron.The constructed iron SACs(h^(3)-FNC)with a high metal loading of 6.27 wt%and an optimized adjacent Fe distance of~4 A exhibit excellent oxidase-like catalytic performance without significant activity decay after being stored for six months and promising antibacterial effects.Attractively,a“density effect”has been found at a high-enough metal doping amount,at which individual active sites become close enough to interact with each other and alter the electronic structure,resulting in significantly boosted intrinsic activity of single-atomic iron sites in h^(3)-FNCs by 2.3 times compared to low-and medium-loading SACs.Consequently,the overall catalytic activity of h^(3)-FNC is highly improved,with mass activity and metal mass-specific activity that are,respectively,66 and 315 times higher than those of commercial Pt/C.In addition,h^(3)-FNCs demonstrate efficiently enhanced capability in catalyzing oxygen reduction into superoxide anion(O_(2)·^(−))and glutathione(GSH)depletion.Both in vitro and in vivo assays demonstrate the superior antibacterial efficacy of h^(3)-FNCs in promoting wound healing.This work presents an intriguing activity-enhancement effect in catalysts and exhibits impressive therapeutic efficacy in combating bacterial infections.展开更多
Nonlinear variations in the coordinate time series of global navigation satellite system(GNSS) reference stations are strongly correlated with surface displacements caused by environmental loading effects,including at...Nonlinear variations in the coordinate time series of global navigation satellite system(GNSS) reference stations are strongly correlated with surface displacements caused by environmental loading effects,including atmospheric, hydrological, and nontidal ocean loading. Continuous improvements in the accuracy of surface mass loading products, performance of Earth models, and precise data-processing technologies have significantly advanced research on the effects of environmental loading on nonlinear variations in GNSS coordinate time series. However, owing to theoretical limitations, the lack of high spatiotemporal resolution surface mass observations, and the coupling of GNSS technology-related systematic errors, environmental loading and nonlinear GNSS reference station displacements remain inconsistent. The applicability and capability of these loading products across different regions also require further evaluation. This paper outlines methods for modeling environmental loading, surface mass loading products, and service organizations. In addition, it summarizes recent advances in applying environmental loading to address nonlinear variations in global and regional GNSS coordinate time series. Moreover, the scientific questions of existing studies are summarized, and insights into future research directions are provided. The complex nonlinear motion of reference stations is a major factor limiting the accuracy of the current terrestrial reference frame. Further refining the environmental load modeling method, establishing a surface mass distribution model with high spatiotemporal resolution and reliability, exploring other environmental load factors such as ice sheet and artificial mass-change effects, and developing an optimal data-processing model and strategy for reprocessing global reference station data consistently could contribute to the development of a millimeter-level nonlinear motion model for GNSS reference stations with actual physical significance and provide theoretical support for establishing a terrestrial reference frame with 1 mm accuracy by 2050.展开更多
This paper proposes a novel cargo loading algorithm applicable to automated conveyor-type loading systems.The algorithm offers improvements in computational efficiency and robustness by utilizing the concept of discre...This paper proposes a novel cargo loading algorithm applicable to automated conveyor-type loading systems.The algorithm offers improvements in computational efficiency and robustness by utilizing the concept of discrete derivatives and introducing logistics-related constraints.Optional consideration of the rotation of the cargoes was made to further enhance the optimality of the solutions,if possible to be physically implemented.Evaluation metrics were developed for accurate evaluation and enhancement of the algorithm’s ability to efficiently utilize the loading space and provide a high level of dynamic stability.Experimental results demonstrate the extensive robustness of the proposed algorithm to the diversity of cargoes present in Business-to-Consumer environments.This study contributes practical advancements in both cargo loading optimization and automation of the logistics industry,with potential applications in last-mile delivery services,warehousing,and supply chain management.展开更多
This work aims to reveal the mechanical responses and energy evolution characteristics of skarn rock under constant amplitude-varied frequency loading paths.Testing results show that the fatigue lifetime,stress−strain...This work aims to reveal the mechanical responses and energy evolution characteristics of skarn rock under constant amplitude-varied frequency loading paths.Testing results show that the fatigue lifetime,stress−strain responses,deformation,energy dissipation and fracture morphology are all impacted by the loading rate.A pronounced influence of the loading rate on rock deformation is found,with slower loading rate eliciting enhanced strain development,alongside augmented energy absorption and dissipation.In addition,it is revealed that the loading rate and cyclic loading amplitude jointly influence the phase shift distribution,with accelerated rates leading to a narrower phase shift duration.It is suggested that lower loading rate leads to more significant energy dissipation.Finally,the tensile or shear failure modes were intrinsically linked to loading strategy,with cyclic loading predominantly instigating shear damage,as manifest in the increased presence of pulverized grain particles.This work would give new insights into the fortification of mining structures and the optimization of mining methodologies.展开更多
The structure optimization design under thermo-mechanical coupling is a difficult problem in the topology optimization field.An adaptive growth algorithm has become a more effective approach for structural topology op...The structure optimization design under thermo-mechanical coupling is a difficult problem in the topology optimization field.An adaptive growth algorithm has become a more effective approach for structural topology optimization.This paper proposed a topology optimization method by an adaptive growth algorithm for the stiffener layout design of box type load-bearing components under thermo-mechanical coupling.Based on the stiffness diffusion theory,both the load stiffness matrix and the heat conduction stiffness matrix of the stiffener are spread at the same time to make sure the stiffener grows freely and obtain an optimal stiffener layout design.Meanwhile,the objectives of optimization are the minimization of strain energy and thermal compliance of the whole structure,and thermo-mechanical coupling is considered.Numerical studies for square shells clearly show the effectiveness of the proposed method for stiffener layout optimization under thermo-mechanical coupling.Finally,the method is applied to optimize the stiffener layout of box type load-bearing component of themachining center.The optimization results show that both the structural deformation and temperature of the load-bearing component with the growth stiffener layout,which are optimized by the adaptive growth algorithm,are less than the stiffener layout of shape‘#’stiffener layout.It provides a new solution approach for stiffener layout optimization design of box type load-bearing components under thermo-mechanical coupling.展开更多
This paper presents an improved level set method for topology optimization of geometrically nonlinear structures accounting for the effect of thermo-mechanical couplings.It derives a new expression for element couplin...This paper presents an improved level set method for topology optimization of geometrically nonlinear structures accounting for the effect of thermo-mechanical couplings.It derives a new expression for element coupling stress resulting from the combination of mechanical and thermal loading,using geometric nonlinear finite element analysis.A topological model is then developed to minimize compliance while meeting displacement and frequency constraints to fulfill design requirements of structural members.Since the conventional Lagrange multiplier search method is unable to handle convergence instability arising from large deformation,a novel Lagrange multiplier search method is proposed.Additionally,the proposed method can be extended to multi-constrained geometrically nonlinear topology optimization,accommodating multiple physical field couplings.展开更多
In this study,a uniaxial cyclic compression test is conducted on coal-rock composite structures under two cyclic loads using MTSE45.104 testing apparatus to investigate the macro-mesoscopic deformation,damage behavior...In this study,a uniaxial cyclic compression test is conducted on coal-rock composite structures under two cyclic loads using MTSE45.104 testing apparatus to investigate the macro-mesoscopic deformation,damage behavior,and energy evolution characteristics of these structures under different cyclic stress disturbances.Three loading and unloading rates(LURs)are tested to examine the damage behaviors and energy-driven characteristics of the composites.The findings reveal that the energy-driven behavior,mechanical properties,and macro-micro degradation characteristics of the composites are significantly influenced by the loading rate.Under the gradual cyclic loading and unloading(CLU)path with a constant lower limit(path I)and the CLU path with variable upper and lower boundaries(path II),an increase in LURs from 0.05 to 0.15 mm/min reduces the average loading time by 32.39%and 48.60%,respectively.Consequently,the total number of cracks in the samples increases by 1.66-fold for path I and 1.41-fold for path II.As LURs further increase,the energy storage limit of samples expands,leading to a higher proportion of transmatrix and shear cracks.Under both cyclic loading conditions,a broader cyclic stress range promotes energy dissipation and the formation of internal fractures.Notably,at higher loading rates,cracks tend to propagate along primary weak surfaces,leading to an increased incidence of intermatrix fractures.This behavior indicates a microscopic feature of the failure mechanisms in composite structures.These results provide a theoretical basis for elucidating the damage and failure characteristics of coal-rock composite structures under cyclic stress disturbances.展开更多
The ambiguity of etiology makes temporomandibular joint osteoarthritis(TMJOA)“difficult-to-treat”.Emerging evidence underscores the therapeutic promise of exosomes in osteoarthritis management.Nonetheless,challenges...The ambiguity of etiology makes temporomandibular joint osteoarthritis(TMJOA)“difficult-to-treat”.Emerging evidence underscores the therapeutic promise of exosomes in osteoarthritis management.Nonetheless,challenges such as low yields and insignificant efficacy of current exosome therapies necessitate significant advances.Addressing lower strontium(Sr)levels in arthritic synovial microenvironment,we studied the effect of Sr element on exosomes and miRNA selectively loading in synovial mesenchymal stem cells(SMSCs).Here,we developed an optimized system that boosts the yield of SMSC-derived exosomes(SMSCEXOs)and improves their miRNA profiles with an elevated proportion of beneficial miRNAs,while reducing harmful ones by pretreating SMSCs with Sr.Compared to untreated SMSC-EXOs,Sr-pretreated SMSC-derived exosomes(Sr-SMSC-EXOs)demonstrated superior therapeutic efficacy by mitigating chondrocyte ferroptosis and reducing osteoclast-mediated joint pain in TMJOA.Our results illustrate Alix’s crucial role in Sr-triggered miRNA loading,identifying miR-143-3p as a key anti-TMJOA exosomal component.Interestingly,this system is specifically oriented towards synovium-derived stem cells.The insight into trace elementdriven,site-specific miRNA selectively loading in SMSC-EXOs proposes a promising therapeutic enhancement strategy for TMJOA.展开更多
Surface deformation calculations due to environmental loading typically rely on the Preliminary Reference Earth Model(PREM),which assumes a homogeneous and isotropic Earth structure,leading to noticeable errors.To enh...Surface deformation calculations due to environmental loading typically rely on the Preliminary Reference Earth Model(PREM),which assumes a homogeneous and isotropic Earth structure,leading to noticeable errors.To enhance accuracy,the high-precision crustal model CRUST 1.0 is used to refine calculations of regional surface deformation caused by hydrological and non-tidal atmospheric loading.The improved model is applied to 27 Global Navigation Satellite System(GNSS)reference stations in the first phase of the Crustal Movement Observation Network of China(CMONOC),considering their geographical locations.Green's functions are employed to compute surface deformation at each site.Results indicate relative discrepancies of 11.78%and 14.14%for non-tidal atmospheric and hydrological loading compared to PREM,with vertical deformation differences reaching an average of 18.95%.Additionally,the distinct spatial distribution characteristics of the relative differences in each direction indicate that the improved RPREM model is more responsive to the mass variations derived from Gravity Recovery and Climate Experiment(GRACE).The results suggest that the improved PRREM model demonstrates higher sensitivity to loading variations than the PREM model.Utilizing the enhanced method of calculating surface deformation through the utilization of Green's function at the site could effectively reduce the calculation error caused by regional structure,leading to enhanced uniformity and isotropy of PREM.展开更多
Background:Trunk lean angle is an underrepre sented biomechanical variable for modulating and redistributing lower extremity joint loading and potentially reducing the risk of running-related overuse injuries.The purp...Background:Trunk lean angle is an underrepre sented biomechanical variable for modulating and redistributing lower extremity joint loading and potentially reducing the risk of running-related overuse injuries.The purpose of this study was to systematically alter the trunk lean angle in distance running using an auditory real-time feedback approach and to derive dose-response relationships between sagittal plane trunk lean angle and lower extremity(cumulative)joint loading to guide overuse load management in clinical practice.Methods:Thirty recreational runners(15 males and 15 females)ran at a constant speed of 2.5 m/s at 5 systematically varied trunk lean conditions on a force-instrumented treadmill while kinematic and kinetic data were captured.Results:A change in trunk lean angle from-2°(extension)to 28°(flexion)resulted in a systematic increase in stance phase angular impulse,cumulative impulse,and peak moment at the hip joint in the sagittal and transversal plane.In contrast,a systematic decrease in these parameters at the knee j oint in the sagittal plane and the hip joint in the frontal plane was found(p<0.001).Linear fitting revealed that with every degree of anterior trunk leaning,the cumulative hip joint extension loading increases by 3.26 Nm·s/kg/1000 m,while simultaneously decreasing knee joint extension loading by 1.08 Nm·s/kg/1000 m.Conclusion:Trunk leaning can reduce knee joint loading and hip joint abduction loading,at the cost of hip joint loading in the sagittal and transversal planes during distance running.Modulating lower extremity joint loading by altering trunk lean angle is an effective strategy to redistribute joint load between/within the knee and hip joints.When implementing anterior trunk leaning in clinical practice,the increased demands on the hip musculature,dynamic stability,and the potential trade-off with running economy should be considered.展开更多
The research on metal dimer clusters is of great importance,owing to the potential in modulating the adsorption behavior towards reaction intermediates.Here,we develop a loading heightening strategy to obtain a 32.5wt...The research on metal dimer clusters is of great importance,owing to the potential in modulating the adsorption behavior towards reaction intermediates.Here,we develop a loading heightening strategy to obtain a 32.5wt%Fe-dimer catalyst(Fe-32.5).The co-anchoring of two Fe atoms in a single triazine ring of carbon nitride with an atomic spacing of∼0.23nm is proved.Fe atoms occupy the pores of the triazine ring in the lower iron content sample(Fe-12.9 and Fe-17.1).However,with the increase of iron content to 32.5wt%,two Fe atoms simultaneously occupy one triazine ring.For Fe-32.5,besides the main peak located at∼1.5Åcorresponding to the Fe–N interaction,a peak attributed to Fe–Fe bonding is observed at∼2.2Åin Fourier-transformed k3-weithted extended X-ray absorption fine structure.Density functional theoretical calculations reveal that Fe-dimer in Fe-32.5 induces a charge redistribution compared with that in Fe-12.9 and Fe-17.1.H_(2)O^(∗)is adsorbed on O^(∗)via hydrogen bonding in Fe-12.9 and Fe-17.1.However,H_(2)O^(∗)and O^(∗)in Fe-32.5 are adsorbed on Fe–Fe dimer,resulting in a decrease in the total energy of the reaction process.For the two former,O_(2)^(-)∗adsorbs on individual Fe atoms.Fe-dimer in Fe-32.5 adsorbs O_(2)^(-)∗in the form of bridge bonds,which facilitates the·O_(2)^(-)release.Furthermore,an enhanced affinity for the substrate 3,3′,5,5′-tetramethylbenzidine and higher peroxidase-like activity were displayed.This work provides an effective mean to synthesize metal dimer clusters through high loading.展开更多
基金National Natural Science Foundation of China (50571005)
文摘Thermal barrier coatings （TBCs） were developed to protect metallic blades and vanes working in turbo-engines. The two-layered structure TBCs, consisting of NiCoCrAlY bond coat and yttria stabilized zirconia （YSZ）, were deposited on a cylinder of superalloy substrate by the electron beam-physical vapor deposition （EB-PVD）. The failure mechanism of the TBCs was investigated with a thermo-mechanical fatigue testing system under the service condition similar to that for turbine blades. Non-destructive evaluation of the coated specimens was conducted through the impedance spectroscopy. It is found that the crack initiation mainly takes place on the top coat at the edge of the heated zones.
文摘Under combined electro-thermo-mechanical loadings, the nonlinear bending of piezoelectric cylindrical shell reinforced with boron nitride nanotubes (BNNTs) is investigated in this paper. By employing nonlinear strains based on Donnell shell theory and utilizing piezoelectric theory including thermal effects, the constitutive relations of the piezoelectric shell reinforced with BNNTs are established. Then the governing equations of the structure are derived through variational principle and resolved by applying the finite difference method. In numerical examples, the effects of geometric nonlinear, voltage, temperature, as well as volume fraction on the deflection and bending moment of axisymmetrical piezoelectric cylindrical shell reinforced with BNNTs are discussed in detail.
基金supported by National Science and Technology Pillar Program in the 11th Five Year Plan of China
文摘Thermo-mechanical fatigue （TMF） behavior of FGH96, a nickel-base powder metallurgy superalloy, has been studied under tension-tension loading at the temperature range from 550 to 720 ℃. The results show that TMF fracture mode is intergranular for the in-phase （IP）, but transgranular cleavage-like for the out-of-phase （OP） samples. The total content of Al, Ti and Nb in the γ＇ phases for the IP or OP samples and the partitioning ratio of γ＇/γin these elements for the IP samples are relatively higher at the lower strain amplitude, which is consistent with the case of the γ＇ size that is larger at the lower strain amplitude, the lattice parameter misfit is negative and the absolute value is lower at the lower strain amplitude that is correlative with the change of the γ＇ morphology. The deformation at the lower strain amplitude is mainly dominated by the dislocation lines and dislocation pairs in the matrix channels, at the higher strain amplitude dominated by the large numbers of superlattice stacking faults within the γ＇ phases.
基金funded by the National Natural Science Foundation of China (51875241,51505180, U1601203)the Jilin Province Science and Technology Development Plan(20180201126GX, 20170101134JC)the China Postdoctoral Science Foundation Funded Project (2017T100205)
文摘Novel crystallization behaviors of Zr55Cu30Al10Ni5 bulk metallic glass are investigated. On the one hand, mixed oxides, including CuO, CuAlO2, CuA12O4 and ZrO2, show sequential oxidation process determined by coupling effects of specific cyclic load and temperature. On the other hand, at a temperature (100℃) by far lower than Tg of 412 ℃, under cyclic loading condition, non-oxidized binary alloy CuZr2 is precipitated;the thermo-mechanical coupled effects of temperature below Tg, and fatigue accumulation on the non-oxidized crystallization behaviors are revealed. Meanwhile, at a constant temperature of 400 ℃, by comparing among the XRD patterns, respectively, obtained from tensile, creep and fatigue fractures, the dominating effect of cyclic load on the generation of non-oxidized CuZr2 is verified. Furthermore, the crystallization behavior of amorphous phases under cyclic loading condition is observed through TEM micrograph and diffraction pattern at 100℃.
基金supported by the Amada Foundation and the 26th ISIJ Research Promotion Grant, Japan。
文摘In the past studies, it has been discovered that the shape memory effect(SME) in the Fe-Mn-Si shape memory alloy(Fe-SMA)can gradually be enhanced by a pre-process called as shape memory training process under cyclic thermo-mechanical loading.On the other hand, it has been shown that the SME of Fe-SMA can also be affected by changing the strain rate. Therefore, it is possible to improve the SME by combining the strain rate sensitivity and shape memory training process. However, the improvement of SME caused by the training process under impact condition is still unclear. For the training process under impact condition, it is difficult to interrupt the test at the desired strain level due to many reflections of stress waves, which reload the specimen from the free ends. In this paper, to obtain reliable experimental results of SME after the training process under impact condition, the stress waves after first loading are eliminated by the double momentum-trap structure introduced into the impact tensile testing apparatus based on the split Hopkinson pressure bar method. In order to achieve an optimum design of the structure used in experiments, the finite element simulation of the structure is performed. Then, tensile tests in the training process of Fe-28Mn-6Si-5Cr alloy at different strain rates including the impact level are conducted and temperature change of the specimen is measured during training and heating process. As a result, the improvement of SME in the alloy after the training process under quasi-static and impact loading is compared with that under quasi-static loading through verification processes.
基金substantially supported by financial support from Grant-in-Aid Scientific Research(B)(Grant No.17H03304)JSPS,and JSPS KAKENHI(Grant No.JP20K14823).
文摘Geological repository of high-level nuclear waste(HLNW),the most feasible approach for the safe and permanent treatment of HLNW without human intervention,has been investigated for years by many researchers.In some countries,real facilities for the geo-logical repository are already under construction.In Japan,however,due to complicated geologic conditions,especially underground water and fractured rock masses,and the high risk of natural disasters,ensuring the long-term stability of the method remains a struggle.The influential factors include underground water,heat generation from radioactive waste,and thermal and chemical weathering of the surrounding rock mass as a natural barrier.It is difficult to estimate and verify the long-term stability for up to one hundred thousand years,a complicated thermal-hydraulic-mechanical-chemical coupling behavior,via any field test.The objective of the study is to develop a numerical method for predicting the long-term stability of geological repositories.As the first step toward realizing this objec-tive,heating and loading tests on cave model made of man-made rock specimens that are composed of diatoms,gypsum,and water,which are viscoplastic materials,were conducted,based on which a newly proposed numerical method with finite element method(FEM)was used to describe the thermal,mechanical,and time-dependent behavior of the model tests for a geological repository.To ensure the accuracy of the numerical calculations,all the material parameters in the thermoelasto-viscoplastic model with consideration of overconsolidation,the structure,and the influence of intermediate stress were determined via triaxial compression/creep tests under various temperatures,confining stresses,and loading rates.Finally,the validity of the numerical method was demonstrated by model tests over a limited time span.
基金supported by the Chongqing Youth Talent Support Program(Cstc2022ycjh-bgzxm0079)the Chinese National Natural Science Foundation(52379128,51979152)+2 种基金Science Fund for Distinguished Young Scholars of Hubei Proivnce(2023AFA048)Educational Commission of Hubei Province of China(T2020005)the Young Top-notch Talent Cultivation Program of Hubei Province.
文摘In rock drilling and blasting,the misfire of electronic detonators will not only affect the rock fragmentation result but also bring serious potential safety hazards to engineering construction.An accurate and comprehensive understanding of the failure mechanisms of electronic detonators subjected to impact loading is of great significance to the reliability design and field safety use of electronic detonators.The spatial distribution characteristics and failure modes of misfired electronic detonators under different application scenarios are statistically analysed.The results show that under high impact loads,electronic detonators will experience failure phenomena such as rupture of the fuse head,fracture of the bridge wire,falling off of the solder joint,chip module damage and insufficient initiation energy after deformation.The lack of impact resistance is the primary cause of misfire of electronic detonators.Combined with the underwater impact resistance test and the impact load test in the adjacent blasthole on site,the formulas of the impact failure probability of the electronic detonator under different stress‒strength distribution curves are deduced.The test and evaluation method of the impact resistance of electronic detonators based on stress‒strength interference theory is proposed.Furthermore,the impact failure model of electronic detonators considering the strength degradation effect under repeated random loads is established.On this basis,the failure mechanism of electronic detonators under different application environments,such as open-pit blasting and underground blasting,is revealed,which provides scientific theory and methods for the reliability analysis,design and type selection of electronic detonators in rock drilling and blasting.
基金financially supported by the National Natural Science Foundation of China(Grant No.42172292)Taishan Scholars Project Special Funding,and Shandong Energy Group(Grant No.SNKJ 2022A01-R26).
文摘A conceptual model of intermittent joints is introduced to the cyclic shear test in the laboratory to explore the effects of loading parameters on its shear behavior under cyclic shear loading.The results show that the loading parameters(initial normal stress,normal stiffness,and shear velocity)determine propagation paths of the wing and secondary cracks in rock bridges during the initial shear cycle,creating different morphologies of macroscopic step-path rupture surfaces and asperities on them.The differences in stress state and rupture surface induce different cyclic shear responses.It shows that high initial normal stress accelerates asperity degradation,raises shear resistance,and promotes compression of intermittent joints.In addition,high normal stiffness provides higher normal stress and shear resistance during the initial cycles and inhibits the dilation and compression of intermittent joints.High shear velocity results in a higher shear resistance,greater dilation,and greater compression.Finally,shear strength is most sensitive to initial normal stress,followed by shear velocity and normal stiffness.Moreover,average dilation angle is most sensitive to initial normal stress,followed by normal stiffness and shear velocity.During the shear cycles,frictional coefficient is affected by asperity degradation,backfilling of rock debris,and frictional area,exhibiting a non-monotonic behavior.
文摘Non-seismically designed(NSD)beam-column joints are susceptible to joint shear failure under seismic loads.Although significant research is available on the seismic behavior of such joints of planar frames,the information on the seismic behavior of joints of space frames(3D joints)is insufficient.The 3D joints are subjected to bi-directional excitation,which results in an interaction between the shear strength obtained for the joint in the two orthogonal directions separately.The bi-directional seismic behavior of corner reinforced concrete(RC)joints is the focus of this study.First,a detailed finite element(FE)model using the FE software Abaqus,is developed and validated using the test results from the literature.The validated modeling procedure is used to conduct a parametric study to investigate the influence of different parameters such as concrete strength,dimensions of main and transverse beams framing into the joint,presence or absence of a slab,axial load ratio and loading direction on the seismic behavior of joints.By subjecting the models to different combinations of loads on the beams along perpendicular directions,the interaction of the joint shear strength in two orthogonal directions is studied.The comparison of the interaction curves of the joints obtained from the numerical study with a quadratic(circular)interaction curve indicates that in a majority of cases,the quadratic interaction model can represent the strength interaction diagrams of RC beam to column connections with governing joint shear failure reasonably well.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB3804500)the National Natural Science Foundation of China(Grant No.52202352,22335006)+4 种基金the Shanghai Municipal Health Commission(Grant No.20224Y0010)the CAMS Innovation Fund for Medical Sciences(Grant No.2021-I2M-5-012)the Basic Research Program of Shanghai Municipal Government(Grant No.21JC1406000)the Fundamental Research Funds for the Central Universities(Grant No.22120230237,2023-3-YB-11,22120220618)the Basic Research Program of Shanghai Municipal Government(23DX1900200).
文摘The current single-atom catalysts(SACs)for medicine still suffer from the limited active site density.Here,we develop a synthetic method capable of increasing both the metal loading and mass-specific activity of SACs by exchanging zinc with iron.The constructed iron SACs(h^(3)-FNC)with a high metal loading of 6.27 wt%and an optimized adjacent Fe distance of~4 A exhibit excellent oxidase-like catalytic performance without significant activity decay after being stored for six months and promising antibacterial effects.Attractively,a“density effect”has been found at a high-enough metal doping amount,at which individual active sites become close enough to interact with each other and alter the electronic structure,resulting in significantly boosted intrinsic activity of single-atomic iron sites in h^(3)-FNCs by 2.3 times compared to low-and medium-loading SACs.Consequently,the overall catalytic activity of h^(3)-FNC is highly improved,with mass activity and metal mass-specific activity that are,respectively,66 and 315 times higher than those of commercial Pt/C.In addition,h^(3)-FNCs demonstrate efficiently enhanced capability in catalyzing oxygen reduction into superoxide anion(O_(2)·^(−))and glutathione(GSH)depletion.Both in vitro and in vivo assays demonstrate the superior antibacterial efficacy of h^(3)-FNCs in promoting wound healing.This work presents an intriguing activity-enhancement effect in catalysts and exhibits impressive therapeutic efficacy in combating bacterial infections.
基金supported by the Basic Science Center Project of the National Natural Science Foundation of China(42388102)the National Natural Science Foundation of China(42174030)+2 种基金the Special Fund of Hubei Luojia Laboratory(220100020)the Major Science and Technology Program for Hubei Province(2022AAA002)the Fundamental Research Funds for the Central Universities of China(2042022dx0001 and 2042023kfyq01)。
文摘Nonlinear variations in the coordinate time series of global navigation satellite system(GNSS) reference stations are strongly correlated with surface displacements caused by environmental loading effects,including atmospheric, hydrological, and nontidal ocean loading. Continuous improvements in the accuracy of surface mass loading products, performance of Earth models, and precise data-processing technologies have significantly advanced research on the effects of environmental loading on nonlinear variations in GNSS coordinate time series. However, owing to theoretical limitations, the lack of high spatiotemporal resolution surface mass observations, and the coupling of GNSS technology-related systematic errors, environmental loading and nonlinear GNSS reference station displacements remain inconsistent. The applicability and capability of these loading products across different regions also require further evaluation. This paper outlines methods for modeling environmental loading, surface mass loading products, and service organizations. In addition, it summarizes recent advances in applying environmental loading to address nonlinear variations in global and regional GNSS coordinate time series. Moreover, the scientific questions of existing studies are summarized, and insights into future research directions are provided. The complex nonlinear motion of reference stations is a major factor limiting the accuracy of the current terrestrial reference frame. Further refining the environmental load modeling method, establishing a surface mass distribution model with high spatiotemporal resolution and reliability, exploring other environmental load factors such as ice sheet and artificial mass-change effects, and developing an optimal data-processing model and strategy for reprocessing global reference station data consistently could contribute to the development of a millimeter-level nonlinear motion model for GNSS reference stations with actual physical significance and provide theoretical support for establishing a terrestrial reference frame with 1 mm accuracy by 2050.
基金supported by the BK21 FOUR funded by the Ministry of Education of Korea and National Research Foundation of Korea,a Korea Agency for Infrastructure Technology Advancement(KAIA)grant funded by the Ministry of Land,Infrastructure,and Transport(Grant 1615013176)IITP(Institute of Information&Coummunications Technology Planning&Evaluation)-ICAN(ICT Challenge and Advanced Network of HRD)grant funded by the Korea government(Ministry of Science and ICT)(RS-2024-00438411).
文摘This paper proposes a novel cargo loading algorithm applicable to automated conveyor-type loading systems.The algorithm offers improvements in computational efficiency and robustness by utilizing the concept of discrete derivatives and introducing logistics-related constraints.Optional consideration of the rotation of the cargoes was made to further enhance the optimality of the solutions,if possible to be physically implemented.Evaluation metrics were developed for accurate evaluation and enhancement of the algorithm’s ability to efficiently utilize the loading space and provide a high level of dynamic stability.Experimental results demonstrate the extensive robustness of the proposed algorithm to the diversity of cargoes present in Business-to-Consumer environments.This study contributes practical advancements in both cargo loading optimization and automation of the logistics industry,with potential applications in last-mile delivery services,warehousing,and supply chain management.
基金Project(52174069) supported by the National Natural Science Foundation of ChinaProject(8202033) supported by the Beijing Natural Science Foundation,ChinaProject(KCF2203) supported by the Henan Key Laboratory for Green and Efficient Mining&Comprehensive Utilization of Mineral Resources (Henan Polytechnic University),China。
文摘This work aims to reveal the mechanical responses and energy evolution characteristics of skarn rock under constant amplitude-varied frequency loading paths.Testing results show that the fatigue lifetime,stress−strain responses,deformation,energy dissipation and fracture morphology are all impacted by the loading rate.A pronounced influence of the loading rate on rock deformation is found,with slower loading rate eliciting enhanced strain development,alongside augmented energy absorption and dissipation.In addition,it is revealed that the loading rate and cyclic loading amplitude jointly influence the phase shift distribution,with accelerated rates leading to a narrower phase shift duration.It is suggested that lower loading rate leads to more significant energy dissipation.Finally,the tensile or shear failure modes were intrinsically linked to loading strategy,with cyclic loading predominantly instigating shear damage,as manifest in the increased presence of pulverized grain particles.This work would give new insights into the fortification of mining structures and the optimization of mining methodologies.
基金supported by National Natural Science Foundation of China (No.52075445)Science,Technology and Innovation Commission of Shenzhen Municipality (No.JCYJ20190806151013025).
文摘The structure optimization design under thermo-mechanical coupling is a difficult problem in the topology optimization field.An adaptive growth algorithm has become a more effective approach for structural topology optimization.This paper proposed a topology optimization method by an adaptive growth algorithm for the stiffener layout design of box type load-bearing components under thermo-mechanical coupling.Based on the stiffness diffusion theory,both the load stiffness matrix and the heat conduction stiffness matrix of the stiffener are spread at the same time to make sure the stiffener grows freely and obtain an optimal stiffener layout design.Meanwhile,the objectives of optimization are the minimization of strain energy and thermal compliance of the whole structure,and thermo-mechanical coupling is considered.Numerical studies for square shells clearly show the effectiveness of the proposed method for stiffener layout optimization under thermo-mechanical coupling.Finally,the method is applied to optimize the stiffener layout of box type load-bearing component of themachining center.The optimization results show that both the structural deformation and temperature of the load-bearing component with the growth stiffener layout,which are optimized by the adaptive growth algorithm,are less than the stiffener layout of shape‘#’stiffener layout.It provides a new solution approach for stiffener layout optimization design of box type load-bearing components under thermo-mechanical coupling.
基金supported by grants from the National Natural Science Foundation of China (51478130)the Guangzhou Municipal Education Bureau’s Scientific Research Project, China (2024312217)+1 种基金the China Scholarship Council (201808440070)the 111 Project of China (D21021).
文摘This paper presents an improved level set method for topology optimization of geometrically nonlinear structures accounting for the effect of thermo-mechanical couplings.It derives a new expression for element coupling stress resulting from the combination of mechanical and thermal loading,using geometric nonlinear finite element analysis.A topological model is then developed to minimize compliance while meeting displacement and frequency constraints to fulfill design requirements of structural members.Since the conventional Lagrange multiplier search method is unable to handle convergence instability arising from large deformation,a novel Lagrange multiplier search method is proposed.Additionally,the proposed method can be extended to multi-constrained geometrically nonlinear topology optimization,accommodating multiple physical field couplings.
基金Project(2023YFC3009003) supported by the National Key R&D Program of ChinaProjects(52130409, 52121003, 52374249, 52204220) supported by the National Natural Science Foundation of ChinaProject(2024JCCXAQ01) supported by the Fundamental Research Funds for the Central Universities,China。
文摘In this study,a uniaxial cyclic compression test is conducted on coal-rock composite structures under two cyclic loads using MTSE45.104 testing apparatus to investigate the macro-mesoscopic deformation,damage behavior,and energy evolution characteristics of these structures under different cyclic stress disturbances.Three loading and unloading rates(LURs)are tested to examine the damage behaviors and energy-driven characteristics of the composites.The findings reveal that the energy-driven behavior,mechanical properties,and macro-micro degradation characteristics of the composites are significantly influenced by the loading rate.Under the gradual cyclic loading and unloading(CLU)path with a constant lower limit(path I)and the CLU path with variable upper and lower boundaries(path II),an increase in LURs from 0.05 to 0.15 mm/min reduces the average loading time by 32.39%and 48.60%,respectively.Consequently,the total number of cracks in the samples increases by 1.66-fold for path I and 1.41-fold for path II.As LURs further increase,the energy storage limit of samples expands,leading to a higher proportion of transmatrix and shear cracks.Under both cyclic loading conditions,a broader cyclic stress range promotes energy dissipation and the formation of internal fractures.Notably,at higher loading rates,cracks tend to propagate along primary weak surfaces,leading to an increased incidence of intermatrix fractures.This behavior indicates a microscopic feature of the failure mechanisms in composite structures.These results provide a theoretical basis for elucidating the damage and failure characteristics of coal-rock composite structures under cyclic stress disturbances.
基金supported by National Natural Science Foundation of China(Nos.82271019,82472149,82471024)Sichuan Science and Technology Program(No.24ZDYF0099)Research and Develop Program,West China Hospital of Stomatology Sichuan University(RD-03-202101)to J.W.
文摘The ambiguity of etiology makes temporomandibular joint osteoarthritis(TMJOA)“difficult-to-treat”.Emerging evidence underscores the therapeutic promise of exosomes in osteoarthritis management.Nonetheless,challenges such as low yields and insignificant efficacy of current exosome therapies necessitate significant advances.Addressing lower strontium(Sr)levels in arthritic synovial microenvironment,we studied the effect of Sr element on exosomes and miRNA selectively loading in synovial mesenchymal stem cells(SMSCs).Here,we developed an optimized system that boosts the yield of SMSC-derived exosomes(SMSCEXOs)and improves their miRNA profiles with an elevated proportion of beneficial miRNAs,while reducing harmful ones by pretreating SMSCs with Sr.Compared to untreated SMSC-EXOs,Sr-pretreated SMSC-derived exosomes(Sr-SMSC-EXOs)demonstrated superior therapeutic efficacy by mitigating chondrocyte ferroptosis and reducing osteoclast-mediated joint pain in TMJOA.Our results illustrate Alix’s crucial role in Sr-triggered miRNA loading,identifying miR-143-3p as a key anti-TMJOA exosomal component.Interestingly,this system is specifically oriented towards synovium-derived stem cells.The insight into trace elementdriven,site-specific miRNA selectively loading in SMSC-EXOs proposes a promising therapeutic enhancement strategy for TMJOA.
基金supported by the National Natural Science Foundation of China(Grant 42204006)the Education Commission of Hubei Province of China(Grant D20232802)+1 种基金the Open Fund of Wuhan,Gravitationand Solid EarthTides,National Observationand Research Station(Grant WHYWZ202407)the Open Fund of Hubei Luojia Laboratory(Grant 230100020,230100019).
文摘Surface deformation calculations due to environmental loading typically rely on the Preliminary Reference Earth Model(PREM),which assumes a homogeneous and isotropic Earth structure,leading to noticeable errors.To enhance accuracy,the high-precision crustal model CRUST 1.0 is used to refine calculations of regional surface deformation caused by hydrological and non-tidal atmospheric loading.The improved model is applied to 27 Global Navigation Satellite System(GNSS)reference stations in the first phase of the Crustal Movement Observation Network of China(CMONOC),considering their geographical locations.Green's functions are employed to compute surface deformation at each site.Results indicate relative discrepancies of 11.78%and 14.14%for non-tidal atmospheric and hydrological loading compared to PREM,with vertical deformation differences reaching an average of 18.95%.Additionally,the distinct spatial distribution characteristics of the relative differences in each direction indicate that the improved RPREM model is more responsive to the mass variations derived from Gravity Recovery and Climate Experiment(GRACE).The results suggest that the improved PRREM model demonstrates higher sensitivity to loading variations than the PREM model.Utilizing the enhanced method of calculating surface deformation through the utilization of Green's function at the site could effectively reduce the calculation error caused by regional structure,leading to enhanced uniformity and isotropy of PREM.
文摘Background:Trunk lean angle is an underrepre sented biomechanical variable for modulating and redistributing lower extremity joint loading and potentially reducing the risk of running-related overuse injuries.The purpose of this study was to systematically alter the trunk lean angle in distance running using an auditory real-time feedback approach and to derive dose-response relationships between sagittal plane trunk lean angle and lower extremity(cumulative)joint loading to guide overuse load management in clinical practice.Methods:Thirty recreational runners(15 males and 15 females)ran at a constant speed of 2.5 m/s at 5 systematically varied trunk lean conditions on a force-instrumented treadmill while kinematic and kinetic data were captured.Results:A change in trunk lean angle from-2°(extension)to 28°(flexion)resulted in a systematic increase in stance phase angular impulse,cumulative impulse,and peak moment at the hip joint in the sagittal and transversal plane.In contrast,a systematic decrease in these parameters at the knee j oint in the sagittal plane and the hip joint in the frontal plane was found(p<0.001).Linear fitting revealed that with every degree of anterior trunk leaning,the cumulative hip joint extension loading increases by 3.26 Nm·s/kg/1000 m,while simultaneously decreasing knee joint extension loading by 1.08 Nm·s/kg/1000 m.Conclusion:Trunk leaning can reduce knee joint loading and hip joint abduction loading,at the cost of hip joint loading in the sagittal and transversal planes during distance running.Modulating lower extremity joint loading by altering trunk lean angle is an effective strategy to redistribute joint load between/within the knee and hip joints.When implementing anterior trunk leaning in clinical practice,the increased demands on the hip musculature,dynamic stability,and the potential trade-off with running economy should be considered.
基金financially supported by National Natural Science Foundation of China(No.52301011)Hainan Provincial Natural Science Foundation of China(No.524QN226)the Opening Project of Key Laboratory of Optoelectronic Chemical Materials and Devices,Ministry of Education,Jianghan University(No.JDGD-202315).
文摘The research on metal dimer clusters is of great importance,owing to the potential in modulating the adsorption behavior towards reaction intermediates.Here,we develop a loading heightening strategy to obtain a 32.5wt%Fe-dimer catalyst(Fe-32.5).The co-anchoring of two Fe atoms in a single triazine ring of carbon nitride with an atomic spacing of∼0.23nm is proved.Fe atoms occupy the pores of the triazine ring in the lower iron content sample(Fe-12.9 and Fe-17.1).However,with the increase of iron content to 32.5wt%,two Fe atoms simultaneously occupy one triazine ring.For Fe-32.5,besides the main peak located at∼1.5Åcorresponding to the Fe–N interaction,a peak attributed to Fe–Fe bonding is observed at∼2.2Åin Fourier-transformed k3-weithted extended X-ray absorption fine structure.Density functional theoretical calculations reveal that Fe-dimer in Fe-32.5 induces a charge redistribution compared with that in Fe-12.9 and Fe-17.1.H_(2)O^(∗)is adsorbed on O^(∗)via hydrogen bonding in Fe-12.9 and Fe-17.1.However,H_(2)O^(∗)and O^(∗)in Fe-32.5 are adsorbed on Fe–Fe dimer,resulting in a decrease in the total energy of the reaction process.For the two former,O_(2)^(-)∗adsorbs on individual Fe atoms.Fe-dimer in Fe-32.5 adsorbs O_(2)^(-)∗in the form of bridge bonds,which facilitates the·O_(2)^(-)release.Furthermore,an enhanced affinity for the substrate 3,3′,5,5′-tetramethylbenzidine and higher peroxidase-like activity were displayed.This work provides an effective mean to synthesize metal dimer clusters through high loading.
