This work focus on the mechanical behaviors,which are related to the size effect,functionally graded(FG)effect and Poisson effect,of an axially functionally graded(AFG)micro-beam whose elastic modulus varies according...This work focus on the mechanical behaviors,which are related to the size effect,functionally graded(FG)effect and Poisson effect,of an axially functionally graded(AFG)micro-beam whose elastic modulus varies according to sinusoidal law along its axial direction.The displacement field of the AFG micro-beam is set according to the Bernoulli-Euler beam theory.Employing the modified couple stress theory(MCST),the components of strain,curvature,stress and couple stress are expressed by the second derivative of the deflection of the AFG micro-beam.A size-dependent model related to FG effect and Poisson effect,which includes the formulations of bending stiffness,deflection,normal stress and couple stress,is developed to predict the mechanical behaviors of the AFG microbeam by employing the principle of minimum potential energy.The mechanical behaviors of a simply supported AFG micro-beam are numerically investigated using the developed model for demonstrating the size effects,FG effects and Poisson effects of the AFG micro-beam.Results show that the mechanical behaviors of AFG micro-beams are distinctly size-dependent only when the ratio of micro-beam height to material length-scale parameter is small enough.The FG parameter is an important factor that determines and regulates the size-dependent behaviors of AFG micro-beams.The influences of Poisson’s ratio on the mechanical behaviors of AFG micro-beams are not negligible,and should be also considered in the design and analysis of an AFG micro-beam.This work supplies a theoretical basis and a technical reference for the design and analysis of AFG micro-beams in the related regions.展开更多
Plant architecture is a critical agronomic trait directly affecting planting density and crop yield.Phosphate(Pi)starvation in rice(Oryza sativa)leads to a significant reduction in tiller number and a more upright lea...Plant architecture is a critical agronomic trait directly affecting planting density and crop yield.Phosphate(Pi)starvation in rice(Oryza sativa)leads to a significant reduction in tiller number and a more upright leaf angle.Insensitivity to brassinosteroid(BR)signaling can lead to similar phenotypes.However,the molecular mechanisms underlying how Piaffects plant architecture through brassinosteroid signaling remain obscure.In this study,we demonstrate that the Pi starvation-induced E3 ligase OsPUB77 regulates rice shoot architecture by affecting leaf angle and tiller number.We further revealed that the Pi-signalingrelated transcription factor RLl1a releases its repression of the expression of OsPUB77 under Pi deficiency.Subsequently,the accumulated OsPUB77 influences shoot architecture by ubiquitinating OsBZR3 to inhibit BR signaling.Furthermore,we found that natural variation in two single-nucleotide polymorphisms within the OsPUB77 U-box domain coding OsPUB77^(R530) results in higher ubiquitin transfer activity than OsPUB77^(1530) due to a strongerinteraction with E2.Introducing the OsPUB77pro::OsPUB77^(R530I) transgene into the ospub77-1 background confirmed that OsPUB77^(R530) results in more upright leaves.Collectively,our work identifies an RLI1a-OsPUB77-OsBZR3 module that mediates the crosstalk between Pi and BR signaling to shape shoot architecture in response to Pi starvation in rice.展开更多
The epoxy shape memory polymer(SMP)with adjustable phase transition temperature is a kind of high-performance shape mem-ory polymer,which can change its phase transition temperature and improve its mechanical properti...The epoxy shape memory polymer(SMP)with adjustable phase transition temperature is a kind of high-performance shape mem-ory polymer,which can change its phase transition temperature and improve its mechanical properties through the process of photo curing.An epoxy SMP constitutive model combining phase transition and viscoelasticity is established by discretizing the epoxy SMP into several glass phase units and rubbery phase units in this paper.The model includes the viscoelastic constitutive equa-tions of glass phase units and rubber phase units,the parameter expression during shape memory process,and material parameter equation during photocuring process.And the stress relaxation behavior of epoxy SMP at different temperatures and the change of material parameters during the photo-curing process are simu-lated numerically,and the simulation results perform consistency with the experimental data.The model can not only relate shape memory effect and phase transformation in physics but also better characterize the viscoelastic properties of SMP and predict the shape memory response of SMP.展开更多
Photosystem Ⅱ(PSⅡ)is a multi-subunit protein complex of the photosynthetic electron transport chain that is vital to photosynthesis.Although the structure,composition,and function of PSⅡ have been extensively studi...Photosystem Ⅱ(PSⅡ)is a multi-subunit protein complex of the photosynthetic electron transport chain that is vital to photosynthesis.Although the structure,composition,and function of PSⅡ have been extensively studied,its biogenesis mechanism remains less understood.Thylakoid rhodanese-like(TROL)provides an anchor for leaf-type ferredoxin:NADP^(+)oxidoreductase.Here,we report the chacterizaton of a second type of TROL protein,TROL2,encoded by seed plant genomes whose function has not previously been reported.We show that TROL2 is a PSⅡ assembly cofactor with essential roles in the establishment of photoautotrophy.TROL2 contains a 45-amino-acid domain,termed the chlorotic lethal seedling(CLS)domain,that is both necessary and sufficient for TROL2 function in PSⅡ assembly and photoautotrophic growth.Phylogenetic analyses suggest that TROL2 may have arisen from ancestral TROL1 via gene duplication before the emergence of seed plants and acquired the CLS domain via evolution of the sequence encoding its N-terminal portion.We further reveal that TROL2(or CLS)forms an assembly cofactor complex with the intrinsic thylakoid membrane protein LOW PSⅡ ACCUMULATION2 and interacts with small PSⅡ subunits to facilitate PSⅡ complex assembly.Collectively,our study not only shows that TROL2(CLS)is essential for photoautotrophy in angiosperms but also reveals its mechanistic role in PSⅡ complex assembly,shedding light on the molecular and evolutionary mechanisms of photosynthetic complex assemblyin angiosperms.展开更多
基金The authors of this paper acknowledge the supports from the National Key Research and Development Program of China(Grant No.2017YFC0307604)the Talent Foundation of China University of Petroleum(Grant No.Y1215042).
文摘This work focus on the mechanical behaviors,which are related to the size effect,functionally graded(FG)effect and Poisson effect,of an axially functionally graded(AFG)micro-beam whose elastic modulus varies according to sinusoidal law along its axial direction.The displacement field of the AFG micro-beam is set according to the Bernoulli-Euler beam theory.Employing the modified couple stress theory(MCST),the components of strain,curvature,stress and couple stress are expressed by the second derivative of the deflection of the AFG micro-beam.A size-dependent model related to FG effect and Poisson effect,which includes the formulations of bending stiffness,deflection,normal stress and couple stress,is developed to predict the mechanical behaviors of the AFG microbeam by employing the principle of minimum potential energy.The mechanical behaviors of a simply supported AFG micro-beam are numerically investigated using the developed model for demonstrating the size effects,FG effects and Poisson effects of the AFG micro-beam.Results show that the mechanical behaviors of AFG micro-beams are distinctly size-dependent only when the ratio of micro-beam height to material length-scale parameter is small enough.The FG parameter is an important factor that determines and regulates the size-dependent behaviors of AFG micro-beams.The influences of Poisson’s ratio on the mechanical behaviors of AFG micro-beams are not negligible,and should be also considered in the design and analysis of an AFG micro-beam.This work supplies a theoretical basis and a technical reference for the design and analysis of AFG micro-beams in the related regions.
基金supported by the National Key Research and Development Program of China(2021YFF1000400)the National Natural Science Foundation of China(32472028)the Natural Science Foundation of Zhejiang Province,China(grant no.LZ25C150003).
文摘Plant architecture is a critical agronomic trait directly affecting planting density and crop yield.Phosphate(Pi)starvation in rice(Oryza sativa)leads to a significant reduction in tiller number and a more upright leaf angle.Insensitivity to brassinosteroid(BR)signaling can lead to similar phenotypes.However,the molecular mechanisms underlying how Piaffects plant architecture through brassinosteroid signaling remain obscure.In this study,we demonstrate that the Pi starvation-induced E3 ligase OsPUB77 regulates rice shoot architecture by affecting leaf angle and tiller number.We further revealed that the Pi-signalingrelated transcription factor RLl1a releases its repression of the expression of OsPUB77 under Pi deficiency.Subsequently,the accumulated OsPUB77 influences shoot architecture by ubiquitinating OsBZR3 to inhibit BR signaling.Furthermore,we found that natural variation in two single-nucleotide polymorphisms within the OsPUB77 U-box domain coding OsPUB77^(R530) results in higher ubiquitin transfer activity than OsPUB77^(1530) due to a strongerinteraction with E2.Introducing the OsPUB77pro::OsPUB77^(R530I) transgene into the ospub77-1 background confirmed that OsPUB77^(R530) results in more upright leaves.Collectively,our work identifies an RLI1a-OsPUB77-OsBZR3 module that mediates the crosstalk between Pi and BR signaling to shape shoot architecture in response to Pi starvation in rice.
基金This work was supported by the National Key Research and Development Program of China[2017YFC0307604].
文摘The epoxy shape memory polymer(SMP)with adjustable phase transition temperature is a kind of high-performance shape mem-ory polymer,which can change its phase transition temperature and improve its mechanical properties through the process of photo curing.An epoxy SMP constitutive model combining phase transition and viscoelasticity is established by discretizing the epoxy SMP into several glass phase units and rubbery phase units in this paper.The model includes the viscoelastic constitutive equa-tions of glass phase units and rubber phase units,the parameter expression during shape memory process,and material parameter equation during photocuring process.And the stress relaxation behavior of epoxy SMP at different temperatures and the change of material parameters during the photo-curing process are simu-lated numerically,and the simulation results perform consistency with the experimental data.The model can not only relate shape memory effect and phase transformation in physics but also better characterize the viscoelastic properties of SMP and predict the shape memory response of SMP.
基金supported by the National Key Research and Development Program of China(2021YFF1000403)the Natural Science Foundation of Zhejiang Province,China(grant no.LZ21C020002).
文摘Photosystem Ⅱ(PSⅡ)is a multi-subunit protein complex of the photosynthetic electron transport chain that is vital to photosynthesis.Although the structure,composition,and function of PSⅡ have been extensively studied,its biogenesis mechanism remains less understood.Thylakoid rhodanese-like(TROL)provides an anchor for leaf-type ferredoxin:NADP^(+)oxidoreductase.Here,we report the chacterizaton of a second type of TROL protein,TROL2,encoded by seed plant genomes whose function has not previously been reported.We show that TROL2 is a PSⅡ assembly cofactor with essential roles in the establishment of photoautotrophy.TROL2 contains a 45-amino-acid domain,termed the chlorotic lethal seedling(CLS)domain,that is both necessary and sufficient for TROL2 function in PSⅡ assembly and photoautotrophic growth.Phylogenetic analyses suggest that TROL2 may have arisen from ancestral TROL1 via gene duplication before the emergence of seed plants and acquired the CLS domain via evolution of the sequence encoding its N-terminal portion.We further reveal that TROL2(or CLS)forms an assembly cofactor complex with the intrinsic thylakoid membrane protein LOW PSⅡ ACCUMULATION2 and interacts with small PSⅡ subunits to facilitate PSⅡ complex assembly.Collectively,our study not only shows that TROL2(CLS)is essential for photoautotrophy in angiosperms but also reveals its mechanistic role in PSⅡ complex assembly,shedding light on the molecular and evolutionary mechanisms of photosynthetic complex assemblyin angiosperms.
