Plant roots are widely known to provide mechanical reinforcement to soils against shearing and further increase slope stability.However,whether roots provide reinforcement to loess cyclic re-sistance and how various f...Plant roots are widely known to provide mechanical reinforcement to soils against shearing and further increase slope stability.However,whether roots provide reinforcement to loess cyclic re-sistance and how various factors affect roots reinforcement during seismic loading have rarely been studied.The objective is to conduct a series of cyclic direct simple shear tests and DEM numerical simulation to investigate the cyclic behaviour of rooted loess.The effects of initial static shear stress and loading frequency on the cyclic resistance of root-soil composites were first investigated.After that,cyclic direct simple shear simulations at constant volume were carried out based on the discrete element method(PFC^(3D))to investigate the effects of root geome-try,mechanical traits and root-soil bond strength on the cyclic strength of rooted loess.It was discovered that the roots could effectively improve the cyclic resistance of loess.The cyclic resistance of the root-soil composite decreases with the increase of the initial shear stress,then increases,and improves with the increase of the frequency.The simulation result show that increases in root elastic modulus and root-soil interfacial bond strength can all enhance the cyclic resistance of root-soil composites,and the maximum cyclic resistance of the root-soil composite was obtained when the initial inclination angle of the root system was 90°.展开更多
Simple cubic black phosphorus(BP)has been recognized as a strategic material due to its exceptional structural stability under extreme conditions.In this investigation,simple cubic BP was successfully synthesized thro...Simple cubic black phosphorus(BP)has been recognized as a strategic material due to its exceptional structural stability under extreme conditions.In this investigation,simple cubic BP was successfully synthesized through shock-induced phase transformation,utilizing amorphous red phosphorus as the precursor material.The phase evolution process was systematically investigated using plane shock loading apparatus,with shock pressure and temperature parameters being precisely controlled to optimize transformation kinetics.Comprehensive phase characterization revealed the correlation between thermodynamic loading profiles and cubic BP formation efficiency.Precursor modification strategies were implemented through orthorhombic BP utilization,resulting in enhanced cubic phase yield and crystallinity.The synthesized cubic BP variants are considered promising candidates for advanced protective material systems,particularly where combinations of mechanical resilience and thermal stability are required under extreme operational conditions.This research provides critical insights into shock-induced phase transformation mechanics,while establishing foundational protocols for manufacturing non-equilibrium materials with potential applications in next-generation defensive technologies.展开更多
Transparent sand is a special material to realize visualization of concealed work in geotechnical engineering. To investigate the dynamic characteristics of transparent sand, a series of undrained cyclic simple shear ...Transparent sand is a special material to realize visualization of concealed work in geotechnical engineering. To investigate the dynamic characteristics of transparent sand, a series of undrained cyclic simple shear tests were conducted on the saturated transparent sand composed of fused quartz and refractive index-matched oil mixture. The results reveal that an increase in the initial shear stress ratio significantly affects the shape of the hysteresis loop, particularly resulting in more pronounced asymmetrical accumulation. Factors such as lower relative density, higher cyclic stress ratios and higher initial shear stress ratio have been shown to accelerate cyclic deformation, cyclic pore water pressure and stiffness degradation. The cyclic liquefaction resistance curves decrease as the initial shear stress ratio increases or as relative density decreases. Booker model and power law function model were applied to predict the pore water pressure for transparent sand. Both models yielded excellent fits for their respective condition, indicating a similar dynamic liquefaction pattern to that of natural sands. Finally, transparent sand displays similar dynamic characteristics in terms of cyclic liquefaction resistance and Kα correction factor. These comparisons indicate that transparent sand can serve as an effective means to mimic many natural sands in dynamic model tests.展开更多
在基因克隆操作中,由于常用克隆载体多克隆位点的酶切位点数目有限,造成一些DNA片段的克隆、连接受限。为解决这一问题,本文利用pEASY-T1 S imp le载体无酶切位点的特点,通过TA克隆的方法引入多个单一酶切位点,并对所构建的克隆载体进...在基因克隆操作中,由于常用克隆载体多克隆位点的酶切位点数目有限,造成一些DNA片段的克隆、连接受限。为解决这一问题,本文利用pEASY-T1 S imp le载体无酶切位点的特点,通过TA克隆的方法引入多个单一酶切位点,并对所构建的克隆载体进行了验证。最后证明,这种方法可高效构建含有不同多克隆位点的载体,克服了对常用克隆载体的依赖,大大提高了基因操作的灵活性和有效性。展开更多
文摘Plant roots are widely known to provide mechanical reinforcement to soils against shearing and further increase slope stability.However,whether roots provide reinforcement to loess cyclic re-sistance and how various factors affect roots reinforcement during seismic loading have rarely been studied.The objective is to conduct a series of cyclic direct simple shear tests and DEM numerical simulation to investigate the cyclic behaviour of rooted loess.The effects of initial static shear stress and loading frequency on the cyclic resistance of root-soil composites were first investigated.After that,cyclic direct simple shear simulations at constant volume were carried out based on the discrete element method(PFC^(3D))to investigate the effects of root geome-try,mechanical traits and root-soil bond strength on the cyclic strength of rooted loess.It was discovered that the roots could effectively improve the cyclic resistance of loess.The cyclic resistance of the root-soil composite decreases with the increase of the initial shear stress,then increases,and improves with the increase of the frequency.The simulation result show that increases in root elastic modulus and root-soil interfacial bond strength can all enhance the cyclic resistance of root-soil composites,and the maximum cyclic resistance of the root-soil composite was obtained when the initial inclination angle of the root system was 90°.
基金supported by the Youth Project of the Independent Subject of the State Key Laboratory of Explosion Science and Safety Protection,Beijing Institute of Technology(Grant Nos.QNKT25-13 and QNKT24-02)the 76th batch of Project funded by China Postdoctoral Science Foundation(Grant No.2024M764116)+3 种基金the National Natural Science Foundation of China(Grant Nos.12002048,12072037,12102050,and 12202067)the Science and Technology Commission,China(Grant No.2019-jcjc-zd-011-00)the Project supported by the Open Funds of Kui Yuan Laboratory(Grant No.KY202431)the State Key Laboratory of Explosion Science and Safety Protection(Grant No.KFJJ25-21M)。
文摘Simple cubic black phosphorus(BP)has been recognized as a strategic material due to its exceptional structural stability under extreme conditions.In this investigation,simple cubic BP was successfully synthesized through shock-induced phase transformation,utilizing amorphous red phosphorus as the precursor material.The phase evolution process was systematically investigated using plane shock loading apparatus,with shock pressure and temperature parameters being precisely controlled to optimize transformation kinetics.Comprehensive phase characterization revealed the correlation between thermodynamic loading profiles and cubic BP formation efficiency.Precursor modification strategies were implemented through orthorhombic BP utilization,resulting in enhanced cubic phase yield and crystallinity.The synthesized cubic BP variants are considered promising candidates for advanced protective material systems,particularly where combinations of mechanical resilience and thermal stability are required under extreme operational conditions.This research provides critical insights into shock-induced phase transformation mechanics,while establishing foundational protocols for manufacturing non-equilibrium materials with potential applications in next-generation defensive technologies.
基金Project(U2268213) supported by the National Natural Science Foundation of ChinaProject(2024YFHZ0121) supported by the Sichuan Science and Technology Program,China。
文摘Transparent sand is a special material to realize visualization of concealed work in geotechnical engineering. To investigate the dynamic characteristics of transparent sand, a series of undrained cyclic simple shear tests were conducted on the saturated transparent sand composed of fused quartz and refractive index-matched oil mixture. The results reveal that an increase in the initial shear stress ratio significantly affects the shape of the hysteresis loop, particularly resulting in more pronounced asymmetrical accumulation. Factors such as lower relative density, higher cyclic stress ratios and higher initial shear stress ratio have been shown to accelerate cyclic deformation, cyclic pore water pressure and stiffness degradation. The cyclic liquefaction resistance curves decrease as the initial shear stress ratio increases or as relative density decreases. Booker model and power law function model were applied to predict the pore water pressure for transparent sand. Both models yielded excellent fits for their respective condition, indicating a similar dynamic liquefaction pattern to that of natural sands. Finally, transparent sand displays similar dynamic characteristics in terms of cyclic liquefaction resistance and Kα correction factor. These comparisons indicate that transparent sand can serve as an effective means to mimic many natural sands in dynamic model tests.
文摘在基因克隆操作中,由于常用克隆载体多克隆位点的酶切位点数目有限,造成一些DNA片段的克隆、连接受限。为解决这一问题,本文利用pEASY-T1 S imp le载体无酶切位点的特点,通过TA克隆的方法引入多个单一酶切位点,并对所构建的克隆载体进行了验证。最后证明,这种方法可高效构建含有不同多克隆位点的载体,克服了对常用克隆载体的依赖,大大提高了基因操作的灵活性和有效性。
