Bridge deformation monitoring usually adopts contact sensors,and the implementation process is often limited by the environment and observation conditions,resulting in unsatisfactory monitoring accuracy and effect.Gro...Bridge deformation monitoring usually adopts contact sensors,and the implementation process is often limited by the environment and observation conditions,resulting in unsatisfactory monitoring accuracy and effect.Ground-Based Synthetic Aperture Radar(GBSAR)combined with corner reflectors was used to perform static load-loaded deformation destruction experiments on solid model bridges in a non-contact manner.The semi parametric spline filtering and its optimization method were used to obtain the monitoring results of the GBSAR radar’s line of sight deformation,and the relative position of the corner reflector and the millimeter level deformation signals under different loading conditions were successfully extracted.The deformation transformation model from the radar line of sight direction to the vertical vibration direction was deduced.The transformation results of deformation monitoring and the measurement data such as the dial indicator were compared and analyzed.The occurrence and development process of bridge deformation and failure were successfully monitored,and the deformation characteristics of the bridge from continuous loading to eccentric loading until bridge failure were obtained.The experimental results show that GBSAR combined with corner reflector can be used for deformation feature acquisition,damage identification and health monitoring of bridges and other structures,and can provide a useful reference for design,construction and safety evaluation.展开更多
A novel robust controller is proposed in this study to realize the precise motion control of a cell puncture mechanism(CPM)driven by piezoelectric ceramics(PEAs).The entire dynamic model of CPM is constructed based on...A novel robust controller is proposed in this study to realize the precise motion control of a cell puncture mechanism(CPM)driven by piezoelectric ceramics(PEAs).The entire dynamic model of CPM is constructed based on the Bouc–Wen model,and the nonlinear part of the dynamic model is optimized locally to facilitate the construction of a robust controller.A model-based,nonlinear robust controller is constructed using time-delay estimation(TDE)and fractional-order nonsingular terminal sliding mode(FONTSM).The proposed controller does not require prior knowledge of unknown disturbances due to its real-time online estimation and compensation of unknown terms by using the TDE technology.The controller also has finite-time convergence and high-precision trajectory tracking capabilities due to FONTSM manifold and fast terminal sliding mode-type reaching law.The stability of the closed-loop system is proved by Lyapunov stability theory.Computer simulation and hardware-in-loop simulation experiments of CPM verify that the proposed controller outperforms traditional terminal sliding mode controllers,such as the integer-order or model-free controller.The proposed controller can also continuously output without chattering and has high control accuracy.Zebrafish embryo is used as a verification target to complete the cell puncture experiment.From the engineering application perspective,the proposed control strategy can be effectively applied in a PEA-driven CPM.展开更多
Chitosan and its degradation product,oligosaccharides,have been shown to facilitate peripheral nerve regeneration.However,the underlying mechanisms are not well understood.In this study,we analyzed the protein express...Chitosan and its degradation product,oligosaccharides,have been shown to facilitate peripheral nerve regeneration.However,the underlying mechanisms are not well understood.In this study,we analyzed the protein expression profiles in sciatic nerves after injury using proteomics.A group of proteins related to exosome packaging and transport is up-regulated by chitosan oligosaccharides(COS),implying that exosomes are involved in COS-induced peripheral nerve regeneration.In fact,exosomes derived from fibroblasts(f-EXOs)treated with COS significantly promoted axon extension and regeneration.Exosomal protein identification and functional studies,revealed that TFAP2C is a key factor in neurite outgrowth induced by COS-f-EXOs.Furthermore,we showed that TFAP2C targets the pri-miRNA-132 gene and represses miR-132-5p expression in dorsal root ganglion neurons.Camkk1 is a downstream substrate of miR-132-5p that positively affects axon extension.In rats,miR-132-5p antagomir stimulates CAMKK1 expression and improves axon regeneration and functional recovery in sciatic nerves after injury.Our data reveal the mechanism for COS in axon regeneration,that is COS induce fibroblasts to produce TFAP2C-enriched EXOs,which are then transferred into axons to promote axon regeneration via miR-132-5p/CAMKK1.Moreover,these results show a new facet of fibroblasts in axon regeneration in peripheral nerves.展开更多
Mg-12 Li, Mg-12 Li-3（Al-Si）, Mg-12 Li-7（Al-Si） and Mg-12 Li-9（Al-Si） alloys（all in wt%） were fabricated by high frequency vacuum induction melting in a water cooled copper crucible. After subsequently hotrolli...Mg-12 Li, Mg-12 Li-3（Al-Si）, Mg-12 Li-7（Al-Si） and Mg-12 Li-9（Al-Si） alloys（all in wt%） were fabricated by high frequency vacuum induction melting in a water cooled copper crucible. After subsequently hotrolling and annealing, their microstructure and mechanical properties were investigated. Experimental results show that mechanical properties of Mg-12 Li alloy were significantly improved by the addition of Al-Si eutectic alloy. Mg-12 Li-7（Al-Si） alloy shows the highest strength of 196 MPa of the investigated alloys, which is about 1.8 times of the strength of Mg-12 Li alloy, and maintains high elongation of 27%.The improved mechanical property with addition of Al and Si in the eutectic proportion into Mg-12 Li alloy was attributed to the solution strengthening effect of A1 and precipitation hardening effect from AlLi and Mg_2 Si precipitates.展开更多
Dear Editor,Cognitive impairment is a hallmark of neurodegenerative disorders such as Alzheimer’s disease（AD）and Parkinson’s disease.Growing evidence has demonstrated that cognitive impairment is closely associate...Dear Editor,Cognitive impairment is a hallmark of neurodegenerative disorders such as Alzheimer’s disease（AD）and Parkinson’s disease.Growing evidence has demonstrated that cognitive impairment is closely associated with insulin resistance.展开更多
基金Science and Technology Innovation Program of Hunan Province(No.2021RC4037)National Natural Science Foundation of China:Deformation Monitoring Key Technology and Damage Mechanism Research on Data Fusion among GB-SAR and Multi-sensors(No.41877283)Scientific Research Project of Hunan Provincial Department of Natural Resources(No.2021-18)
文摘Bridge deformation monitoring usually adopts contact sensors,and the implementation process is often limited by the environment and observation conditions,resulting in unsatisfactory monitoring accuracy and effect.Ground-Based Synthetic Aperture Radar(GBSAR)combined with corner reflectors was used to perform static load-loaded deformation destruction experiments on solid model bridges in a non-contact manner.The semi parametric spline filtering and its optimization method were used to obtain the monitoring results of the GBSAR radar’s line of sight deformation,and the relative position of the corner reflector and the millimeter level deformation signals under different loading conditions were successfully extracted.The deformation transformation model from the radar line of sight direction to the vertical vibration direction was deduced.The transformation results of deformation monitoring and the measurement data such as the dial indicator were compared and analyzed.The occurrence and development process of bridge deformation and failure were successfully monitored,and the deformation characteristics of the bridge from continuous loading to eccentric loading until bridge failure were obtained.The experimental results show that GBSAR combined with corner reflector can be used for deformation feature acquisition,damage identification and health monitoring of bridges and other structures,and can provide a useful reference for design,construction and safety evaluation.
文摘A novel robust controller is proposed in this study to realize the precise motion control of a cell puncture mechanism(CPM)driven by piezoelectric ceramics(PEAs).The entire dynamic model of CPM is constructed based on the Bouc–Wen model,and the nonlinear part of the dynamic model is optimized locally to facilitate the construction of a robust controller.A model-based,nonlinear robust controller is constructed using time-delay estimation(TDE)and fractional-order nonsingular terminal sliding mode(FONTSM).The proposed controller does not require prior knowledge of unknown disturbances due to its real-time online estimation and compensation of unknown terms by using the TDE technology.The controller also has finite-time convergence and high-precision trajectory tracking capabilities due to FONTSM manifold and fast terminal sliding mode-type reaching law.The stability of the closed-loop system is proved by Lyapunov stability theory.Computer simulation and hardware-in-loop simulation experiments of CPM verify that the proposed controller outperforms traditional terminal sliding mode controllers,such as the integer-order or model-free controller.The proposed controller can also continuously output without chattering and has high control accuracy.Zebrafish embryo is used as a verification target to complete the cell puncture experiment.From the engineering application perspective,the proposed control strategy can be effectively applied in a PEA-driven CPM.
基金supported by the National Natural Science Foundation of China(Nos.32230057,81970747,32271193)the National Key Research and Development Program of China(No.2017YFA0701304)the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions.
文摘Chitosan and its degradation product,oligosaccharides,have been shown to facilitate peripheral nerve regeneration.However,the underlying mechanisms are not well understood.In this study,we analyzed the protein expression profiles in sciatic nerves after injury using proteomics.A group of proteins related to exosome packaging and transport is up-regulated by chitosan oligosaccharides(COS),implying that exosomes are involved in COS-induced peripheral nerve regeneration.In fact,exosomes derived from fibroblasts(f-EXOs)treated with COS significantly promoted axon extension and regeneration.Exosomal protein identification and functional studies,revealed that TFAP2C is a key factor in neurite outgrowth induced by COS-f-EXOs.Furthermore,we showed that TFAP2C targets the pri-miRNA-132 gene and represses miR-132-5p expression in dorsal root ganglion neurons.Camkk1 is a downstream substrate of miR-132-5p that positively affects axon extension.In rats,miR-132-5p antagomir stimulates CAMKK1 expression and improves axon regeneration and functional recovery in sciatic nerves after injury.Our data reveal the mechanism for COS in axon regeneration,that is COS induce fibroblasts to produce TFAP2C-enriched EXOs,which are then transferred into axons to promote axon regeneration via miR-132-5p/CAMKK1.Moreover,these results show a new facet of fibroblasts in axon regeneration in peripheral nerves.
基金supported by the Shanxi Scholarship Council of China (No.2014-029)the National Natural Science Foundation of China (Nos. 51474152, 51401143 and 51274149)
文摘Mg-12 Li, Mg-12 Li-3（Al-Si）, Mg-12 Li-7（Al-Si） and Mg-12 Li-9（Al-Si） alloys（all in wt%） were fabricated by high frequency vacuum induction melting in a water cooled copper crucible. After subsequently hotrolling and annealing, their microstructure and mechanical properties were investigated. Experimental results show that mechanical properties of Mg-12 Li alloy were significantly improved by the addition of Al-Si eutectic alloy. Mg-12 Li-7（Al-Si） alloy shows the highest strength of 196 MPa of the investigated alloys, which is about 1.8 times of the strength of Mg-12 Li alloy, and maintains high elongation of 27%.The improved mechanical property with addition of Al and Si in the eutectic proportion into Mg-12 Li alloy was attributed to the solution strengthening effect of A1 and precipitation hardening effect from AlLi and Mg_2 Si precipitates.
基金supported by the National Natural Science Foundation of China (81471037 and 81770841)the "Six Kinds of Talents Summit" of Jiangsu Province, China (SWYY-051)+1 种基金Basic Research Program of Education Department of Jiangsu Province, China (14KJA180006)the Program for New Technology of Clinical Diagnosis and Treatment at Nantong (MS22016024)
文摘Dear Editor,Cognitive impairment is a hallmark of neurodegenerative disorders such as Alzheimer’s disease（AD）and Parkinson’s disease.Growing evidence has demonstrated that cognitive impairment is closely associated with insulin resistance.
