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| 1 | The YDA-MKK4/MKK5-MPK3/MPK6 Cascade Functions Downstream of the RGF1-RGI Ligand-Receptor Pair in Regulating Mitotic Activity in Root Apical Meristem显示文摘The mitotic activity of root apical meristem(RAM)is critical to primary root growth and development.Previous studies have identified the roles of ROOT GROWTH FACTOR 1(RGF1),a peptide ligand,and its receptors,RGF1 INSENSITIVEs(RGIs),a clade of five leucine-rich-repeat receptor-like kinases,in promoting cell division in the RAM,which determines the primary root length.However,the downstream signaling components remain elusive.In this study,we identify a complete mitogen-activated protein kinase(MAPK or MPK)cascade,composed of YDA,MKK4/MKK5,and MPK3/MPK6,that functions downstream of the RGF1-RGI ligand-receptor pair.Similar to the rgi1/2/3/4/5 quintuple mutant,loss-of-function mutants of MPK3 and MPK6,MKK4 and MKK5,or YDA show a short-root phenotype,which is associated with reduced mitotic activity and lower expression of PLETHORA 1(PLT1)/PLT2 in the RAM.Furthermore,MPK3/MPK6 activation in response to exogenous RGF1 treatment is impaired in the rgi1/2/3/4/5 quintuple,yda single,and mkk4 m kk5 double mutants.Epistatic analyses demonstrated that the expression of constitutively active MKK4,MKK5,or YDA driven by the RGI2 promoter can rescue the short-root phenotype of the rgi1/2/3/4/5 mutant.Taken together,these results suggest that the YDA-MKK4/MKK5-MPK3/MPK6 cascade functions downstream of the RGF1-RGI ligand-receptor pair and upstream of PLT1/PLT2 to modulate the stem cell population and primary root growth in Arabidopsis. | Yiming Shao Xinxing Yu Xuwen Xu Yong Li Wenxin Yuan Yan Xu Chuanzao Mao Shuqun Zhang Juan Xu | 2020 | Molecular Plant2020，13，11： | 6 |
| 2 | Integrated design of topology and material for composite morphing trailing edge based compliant mechanism显示文摘The morphing trailing edge based compliant mechanism is a developing technology which can increase lift-drag ratio for variable flight modes by bending down the trailing edge.Composite material design is integrated into topology optimization for the morphing trailing edge based compliant mechanism in the paper.A two-step optimization strategy is established to solve the integrated design problem.Initially,lamination parameters are introduced and viewed as a bridge between structure stiffness and fiber angles for composite material.Design variables include the lamination parameters and element density.The least-squares between actual and desired displacements at output points along trailing edge is adopted to evaluate the deformed capability of the trailing edge.An integrated optimization model for the composite morphing trailing edge is established with the volume constraints.The optimal topologic shape and lamination parameters are initially obtained.Subsequently,a least-squares optimization between fiber angles and the optimal lamination parameters is implemented to obtain optimal fiber angles.Finally,morphing capability of composites trailing edge based compliant mechanism is investigated by simulation and experiments.The results indicate the composites trailing edge based compliant mechanism can approximately bend down 8 degrees and satisfies the design requirement. | Xinxing TONG Wenjie GE Zhenyi YUAN Dajing GAO Xinqin GAO | 2021 | Chinese Journal of Aeronautics2021，34，5： | 2 |
| 3 | Breakdown of effective-medium theory by a photonic spin Hall effect显示文摘Effective-medium theory pertains to the theoretical modelling of homogenization,which aims to replace an inhomogeneous structure of subwavelength-scale constituents with a homogeneous effective medium.The effective-medium theory is fundamental to various realms,including electromagnetics and material science,since it can largely decrease the complexity in the exploration of light-matter interactions by providing simple acceptable approximation.Generally,the effective-medium theory is thought to be applicable to any all-dielectric system with deep-subwavelength constituents,under the condition that the effective medium does not have a critical angle,at which the total internal reflection occurs.Here we reveal a fundamental breakdown of the effective-medium theory that can be applied in very general conditions:showing it for deep-subwavelength all-dielectric multilayers even without a critical angle.Our finding relies on an exotic photonic spin Hall effect,which is shown to be ultrasensitive to the stacking order of deep-subwavelength dielectric layers,since the spin-orbit interaction of light is dependent on slight phase accumulations during the wave propagation.Our results indicate that the photonic spin Hall effect could provide a promising and powerful tool for measuring structural defects for all-dielectric systems even in the extreme nanometer scale. | Shuaijie Yuan Xinxing Zhou Yu Chen Yuhan Zhong Lijuan Sheng Hao Hu Hongsheng Chen Ido Kaminer Xiao Lin | 2023 | Science China(Physics,Mechanics & Astronomy)2023，66，11： | 0 |
| 4 | Over-height truck collisions with railway bridges:attenuation of damage using crash beams显示文摘Railway bridges are susceptible to over-height truck collisions and to address this issue,it is necessary to attenuate the effect of these impacts to ensure the safety of transportation operations.This study experimentally investigates the effectiveness of crash beams as a cushioning mechanism for railway bridges against collisions.Over-height truck and railway bridge impact events were simulated in a 1:5 scale experiment.The design parameters such as the stiffness of the crash beam and the bridge supports were scaled to evaluate different levels of attenuation.Seventeen experiments were conducted with five configurations consisting of four different types of crash beams and one no-crash beam arrangement.The results show that crash beams attenuate bridge total peak dynamic displacement responses between 14.5%and 35.7%,depending on the intensity of the impact and crash beam type.In addition,the results show that the average effectiveness in attenuating residual deformation for all four crash beams ranges from 43.03%to 83.40%.Finally,various designs and their effectiveness against lateral impacts with different speeds are discussed.The overall scope of this research is to provide objective information about the design of crash beams for railway bridges based on their response to over-height truck collisions at various speeds. | Dan Xu Xinxing Yuan Ali Irmak Ozdagli Marlon Agüero Roya Nasimi Tao Wang Fernando Moreu | 2022 | Earthquake Engineering and Engineering Vibration2022，21，1： | 0 |
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