The safety and reliability of space connection and separation device has become a key issue due to the increasing service span of deep space exploration mission.The long-term preload relaxation(a key failure mode)of c...The safety and reliability of space connection and separation device has become a key issue due to the increasing service span of deep space exploration mission.The long-term preload relaxation(a key failure mode)of connection and separation devices is focused in this paper.A series of tests have been designed and implemented to investigate the preload relaxation regulation and a comprehensive method has been constructed to analyze and predict the reliable lifetime of the device.The two-stage preload relaxation law of the device is found and reasonably considered.Due to the different relaxation mechanism,the first-stage preload relaxation is assessed based on the working-condition test results,and the second-stage preload relaxation is characterized by accelerated test results.Finally,the service reliability and reliable life are evaluated.The experiment and assessment results demonstrate the reasonability and effectiveness of the proposed method which can achieve long-service reliability analysis for space connection and separation device within limited time.展开更多
As one of the main areas of tropical storm action in the northwestern Pacific Ocean,South China experiences several typhoons each year,and coastal erosion is a problem,making the area a natural testing ground for stud...As one of the main areas of tropical storm action in the northwestern Pacific Ocean,South China experiences several typhoons each year,and coastal erosion is a problem,making the area a natural testing ground for studying the dynamic geomorphological processes and storm response of promontory-straight coasts.This study is based on three years of topographic data and remote sensing imagery of Gulei Beach and uses topographic profile morphology,single width erosion-accretion and mean change,combined with the Coastsat model to quantify the seasonal and interannual variability and storm response of the beach and to explain the evolution of shoreline change and beach dynamics geomorphology in the last decade.Gulei Beach has been in a state of overall erosion and local accretion for a long time,with relatively obvious cyclical changes;seasonal changes are also obvious,which are mainly characterized by summer accretion and winter erosion,with accretion at the top of the bay and accretion and erosion on the north and south sides of the bay corner,respectively;the seasonal erosion-accretion volume of the beach profile ranges from-80 m3/m to 95.52 m3/m,and the interannual erosion-accretion volume ranges from-69.09 m3/m to 87.31 m3/m.The response of beaches to typhoons with different paths varies greatly depending on the length,slope,orientation and scale of beach development.The large and gently developing Futou beach is less responsive to storms,while the less developed headlands in the southern Gulei Peninsula are more susceptible to disturbance by external factors and respond more strongly to typhoons.Storm distance is more influential than storm intensity.Under the influence of human activities,obvious erosion hotspots develop during normal weather,but storm processes produce redistribution of beach material patterns,and erosion hotspots disappear after storms.The results of this study enrich the theory of beach dynamics geomorphology and provide technical support for disaster prevention and mitigation,as well as ecological restoration of coastal zones.展开更多
Fast and high-throughput determination of drugs is a key trend in clinical medicine.Single particles have increasingly been adopted in a variety of photoanalytical and electroanalytical applications,and microscopic an...Fast and high-throughput determination of drugs is a key trend in clinical medicine.Single particles have increasingly been adopted in a variety of photoanalytical and electroanalytical applications,and microscopic analysis has been a hot topic in recent years,especially for electrochemiluminescence(ECL).This paper describes a simple ECL method based on single gold microbeads to image lecithin.Lecithin reacts to produce hydrogen peroxide under the successive enzymatic reaction of phospholipase D and choline oxidase.ECL was generated by the electrochemical reaction between a luminol analog and hydrogen peroxide,and ECL signals were imaged by a camera.Despite the heterogeneity of single gold microbeads,their luminescence obeyed statistical regularity.The average luminescence of 30 gold microbeads is correlated with the lecithin concentration,and thus,a visualization method for analyzing lecithin was established.Calibration curves were constructed for ECL intensity and lecithin concentration,achieving detection limits of 0.05 m M lecithin.This ECL imaging platform based on single gold microbeads exhibits outstanding advantages,such as high throughput,versatility and low cost,and holds great potential in disease diagnostics,environmental monitoring and food safety.展开更多
Extreme storm events in coastal zones play significant roles in shaping the morphology of boulder beaches.However,boulder displacement and the geomorphological evolution of boulder beaches driven by different extreme ...Extreme storm events in coastal zones play significant roles in shaping the morphology of boulder beaches.However,boulder displacement and the geomorphological evolution of boulder beaches driven by different extreme storm events,especially typhoon events,remain poorly understood.Thus,boulder displacement and the geomorphic response on a boulder beach in Fujian,southeastern China,were explored before,during and after a cold wave event(Dec.1–7,2020)and before and after Typhoon In-Fa(Jul.19–27,2021),a large tropical storm.This was achieved by tracking 42 tagged boulders distributed in the intertidal and supratidal zones using Radio Frequency Identification(RFID)and topographic surveys using real-time kinematic techniques,respectively.The results showed obvious disparities in boulder displacement in different geomorphic zones due to cold wave and typhoon events that were mainly characterized by migration magnitude,range,direction,and mode of transport.The typhoon event led to rapid and substantial changes in the overall morphology of the boulder beach,while the cold wave event impacted the intertidal morphology of the boulder beach to only a small extent.The surrounding structure of boulders,beach slope and beach elevation had a combined dominant effect on boulder displacement under the same extreme event.Hydrodynamic factors(effective wave energy fluxes,incident wave direction,storm surge and water level)had dominant effects on boulder displacement during different extreme events.In terms of a single event,the magnitude of the boulder displacement driven by the typhoon was much greater than that driven by the cold wave.However,considering the frequency and duration of cold waves in winter,the impact of multiple consecutive cold waves on the geomorphology of the boulder beach cannot be ignored in this study area.Alternating and repeated interactions between these two processes constitute the complete geomorphic evolution of the boulder beach.This study contributes to improved predictions of the morphodynamic response of boulder beaches to future storms,especially large tropical storms,and facilitates better coastal management.展开更多
The clay mineralogy of 28 sandy-muddy transitional beach(SMT-Beach)sediments and surrounding mountain river sediments along the coasts of southeastern China was systematically investigated to reveal the sediment sourc...The clay mineralogy of 28 sandy-muddy transitional beach(SMT-Beach)sediments and surrounding mountain river sediments along the coasts of southeastern China was systematically investigated to reveal the sediment source-to-sink process variations of such beaches and their morphological indications.The results show that the clay mineral assemblages of these SMT-Beaches mainly comprise of almost equal illite(~30%),kaolinite(~28%),chlorite(~22%),and smectite(~20%)contents.From the surrounding mountain rivers to the SMT-Beaches,clay mineral assemblages show distinct spatial changes characterized by a large decrease(~40%)in kaolinite,whereas the other three clay minerals present relative increases,especially clear for smectite.The muddy sediment sources of SMT-Beaches inferred from the clay mineralogy are mainly derived from nearby mountain rivers coupled with long-distance transport and penetration of the Changjiang River.The sandy sediments of these beaches are predominantly sourced from nearby mountain rivers,the weathering products of surrounding rocks in both mainland and island environments,and erosion of the“Old Red Sand”and“Red Soil Platform”.However,the sandy sediment sources of the SMT-Beaches are largely reduced because of the remarkable decrease in the river fluvial supply associated with intensive human activities such as dam construction and coastal reclamation.Subsequently,the sandy sections of SMT-Beaches present clear erosion and have revealed by both time series remote sensing images and a compilation of published literature.In contrast,the muddy sediment supply of SMT-Beaches is temporarily stable and relatively constant,resulting in the landward migration of the mudflats with relative transgression or accumulation.These findings highlight that the natural evolution processes of SMT-Beaches have been greatly reshaped by intensive human activities.展开更多
The cross-shore variation in wind speeds influenced by beach nourishment,especially the dramatic changes at the nourished berm,is important for understanding the aeolian sand transport processes that occur after beach...The cross-shore variation in wind speeds influenced by beach nourishment,especially the dramatic changes at the nourished berm,is important for understanding the aeolian sand transport processes that occur after beach nourishment,which will contribute to better beach nourishment project design on windy coasts.In this paper,the influencing factors and potential mechanism of wind speed variation at the edge of a nourished berm were studied.Field observations,together with the Duna model,were used to study the cross-shore wind speed distribution for different nourishment schemes.The results show that the nourished berm elevation and beachface slope are the main factors controlling the increase in wind speed at the berm edge.When the upper beach slope is constant,the wind speed at the berm edge has a positive linear correlation with the berm elevation.When the berm elevation remains constant,the wind speed at the berm edge is also proportional to the upper beach slope.Considering the coupling effects of nourished berm elevation and beachface slope,a model for predicting the wind speed amplification rate at the nourished berm edge was established,and the underlying coupling mechanism was illustrated.展开更多
The N-H methylsulfoxidation of sulfoximines using DMso as a methylsulfinyl source,induced by electrochemistry,has been developed.This method is the first example of an electrochemical reaction in which DMso serves as ...The N-H methylsulfoxidation of sulfoximines using DMso as a methylsulfinyl source,induced by electrochemistry,has been developed.This method is the first example of an electrochemical reaction in which DMso serves as a methylsulfinyl source.Unlike previous electrochemical reactions involving DMsO as a substrate,which exclusively proceed via radical mechanisms,this reaction follows an S-cation pathway.A wide range of N-methylsulfinyl sulfoximines were successfully obtained.展开更多
Recent evidence highlights multifaceted biological needs to recapitulate the bone microenvironment for bone regeneration.Neurotization has great potential for realizing multi-system modulations in bone tissue engineer...Recent evidence highlights multifaceted biological needs to recapitulate the bone microenvironment for bone regeneration.Neurotization has great potential for realizing multi-system modulations in bone tissue engineering(BTE).However,a neural strategy involving all the key bone repair steps temporally has not yet been reported.In this study,we reported the neural tissue engineering hydrogel-encapsulated Schwann cell-derived exosomes(SC Exo).This sustained-release SC Exo system prominently enhanced bone regeneration by promoting innervation,immunoregulation,vascularization,and osteogenesis in vivo.Moreover,the in vitro results further confirmed that this system significantly induced M2 polarization of macrophages,tube formation of HUVECs,and BMSCs osteogenic differentiation.Furthermore,BMSCs osteogenesis was promoted by upregulating the TGF-β1/SMAD2/3 signaling pathway.In summary,a novel cell-free and easily prepared SC Exo neural engineering was successfully developed to promote bone regeneration by orchestrating the entire bone healing microenvironment,which may provide a new strategy for tissue engineering and clinical treatment of bone defects.展开更多
Background:Digital twin requires virtual reality mapping and optimization iteration between physical devices and virtual models.The mechanical movement data collection of physical equipment is essential for the implem...Background:Digital twin requires virtual reality mapping and optimization iteration between physical devices and virtual models.The mechanical movement data collection of physical equipment is essential for the implementation of accurate virtual and physical synchronization in a digital twin environment.However,the traditional approach relying on PLC(programmable logic control)fails to collect various mechanical motion state data.Additionally,few investigations have used machine visions for the virtual and physical synchronization of equipment.Thus,this paper presents a mechanical movement data acquisition method based on multilayer neural networks and machine vision.Methods:Firstly,various visual marks with different colors and shapes are designed for marking physical devices.Secondly,a recognition method based on the Hough transform and histogram feature is proposed to realize the recognition of shape and color features respectively.Then,the multilayer neural network model is introduced in the visual mark location.The neural network is trained by the dropout algorithm to realize the tracking and location of the visual mark.To test the proposed method,1000 samples were selected.Results:The experiment results shows that when the size of the visual mark is larger than 6mm,the recognition success rate of the recognition algorithm can reach more than 95%.In the actual operation environment with multiple cameras,the identification points can be located more accurately.Moreover,the camera calibration process of binocular and multi-eye vision can be simplified by the multilayer neural networks.Conclusions:This study proposes an effective method in the collection of mechanical motion data of physical equipment in a digital twin environment. Further studies are needed to perceive posture and shape data of physical entities under the multi-camera redundant shooting.展开更多
基金supported by the National Natural Science Foundation of China(No.11872085)。
文摘The safety and reliability of space connection and separation device has become a key issue due to the increasing service span of deep space exploration mission.The long-term preload relaxation(a key failure mode)of connection and separation devices is focused in this paper.A series of tests have been designed and implemented to investigate the preload relaxation regulation and a comprehensive method has been constructed to analyze and predict the reliable lifetime of the device.The two-stage preload relaxation law of the device is found and reasonably considered.Due to the different relaxation mechanism,the first-stage preload relaxation is assessed based on the working-condition test results,and the second-stage preload relaxation is characterized by accelerated test results.Finally,the service reliability and reliable life are evaluated.The experiment and assessment results demonstrate the reasonability and effectiveness of the proposed method which can achieve long-service reliability analysis for space connection and separation device within limited time.
基金The National Natural Science Foundation of China under contract Nos 42076058 and 41930538the National Key Research and Development Program of China under contract No.2022YFC3106104the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources under contract Nos 2023023 and 2019017。
文摘As one of the main areas of tropical storm action in the northwestern Pacific Ocean,South China experiences several typhoons each year,and coastal erosion is a problem,making the area a natural testing ground for studying the dynamic geomorphological processes and storm response of promontory-straight coasts.This study is based on three years of topographic data and remote sensing imagery of Gulei Beach and uses topographic profile morphology,single width erosion-accretion and mean change,combined with the Coastsat model to quantify the seasonal and interannual variability and storm response of the beach and to explain the evolution of shoreline change and beach dynamics geomorphology in the last decade.Gulei Beach has been in a state of overall erosion and local accretion for a long time,with relatively obvious cyclical changes;seasonal changes are also obvious,which are mainly characterized by summer accretion and winter erosion,with accretion at the top of the bay and accretion and erosion on the north and south sides of the bay corner,respectively;the seasonal erosion-accretion volume of the beach profile ranges from-80 m3/m to 95.52 m3/m,and the interannual erosion-accretion volume ranges from-69.09 m3/m to 87.31 m3/m.The response of beaches to typhoons with different paths varies greatly depending on the length,slope,orientation and scale of beach development.The large and gently developing Futou beach is less responsive to storms,while the less developed headlands in the southern Gulei Peninsula are more susceptible to disturbance by external factors and respond more strongly to typhoons.Storm distance is more influential than storm intensity.Under the influence of human activities,obvious erosion hotspots develop during normal weather,but storm processes produce redistribution of beach material patterns,and erosion hotspots disappear after storms.The results of this study enrich the theory of beach dynamics geomorphology and provide technical support for disaster prevention and mitigation,as well as ecological restoration of coastal zones.
基金supported by Anhui Provincial Natural Science Foundation(Grant Nos.2008085QB68 and 1808085QB29)Key Project of Provincial Natural Science Research Foundation of Anhui Universities(Grant Nos.KJ2018A0675 and KJ2018A0389)+1 种基金Foundation of State Key Laboratory of Analytical Chemistry for Life Science(Grant No.SKLACLS2003)Foundation of Henan Key Laboratory of Biomolecular Recognition and Sensing(Grant No.HKLBRSK1905)。
文摘Fast and high-throughput determination of drugs is a key trend in clinical medicine.Single particles have increasingly been adopted in a variety of photoanalytical and electroanalytical applications,and microscopic analysis has been a hot topic in recent years,especially for electrochemiluminescence(ECL).This paper describes a simple ECL method based on single gold microbeads to image lecithin.Lecithin reacts to produce hydrogen peroxide under the successive enzymatic reaction of phospholipase D and choline oxidase.ECL was generated by the electrochemical reaction between a luminol analog and hydrogen peroxide,and ECL signals were imaged by a camera.Despite the heterogeneity of single gold microbeads,their luminescence obeyed statistical regularity.The average luminescence of 30 gold microbeads is correlated with the lecithin concentration,and thus,a visualization method for analyzing lecithin was established.Calibration curves were constructed for ECL intensity and lecithin concentration,achieving detection limits of 0.05 m M lecithin.This ECL imaging platform based on single gold microbeads exhibits outstanding advantages,such as high throughput,versatility and low cost,and holds great potential in disease diagnostics,environmental monitoring and food safety.
基金The National Natural Science Foundation of China under contract No.41930538the Scientific Research Foundation of the Third Institute of Oceanography,Ministry of Natural Resources under contract No.2019029.
文摘Extreme storm events in coastal zones play significant roles in shaping the morphology of boulder beaches.However,boulder displacement and the geomorphological evolution of boulder beaches driven by different extreme storm events,especially typhoon events,remain poorly understood.Thus,boulder displacement and the geomorphic response on a boulder beach in Fujian,southeastern China,were explored before,during and after a cold wave event(Dec.1–7,2020)and before and after Typhoon In-Fa(Jul.19–27,2021),a large tropical storm.This was achieved by tracking 42 tagged boulders distributed in the intertidal and supratidal zones using Radio Frequency Identification(RFID)and topographic surveys using real-time kinematic techniques,respectively.The results showed obvious disparities in boulder displacement in different geomorphic zones due to cold wave and typhoon events that were mainly characterized by migration magnitude,range,direction,and mode of transport.The typhoon event led to rapid and substantial changes in the overall morphology of the boulder beach,while the cold wave event impacted the intertidal morphology of the boulder beach to only a small extent.The surrounding structure of boulders,beach slope and beach elevation had a combined dominant effect on boulder displacement under the same extreme event.Hydrodynamic factors(effective wave energy fluxes,incident wave direction,storm surge and water level)had dominant effects on boulder displacement during different extreme events.In terms of a single event,the magnitude of the boulder displacement driven by the typhoon was much greater than that driven by the cold wave.However,considering the frequency and duration of cold waves in winter,the impact of multiple consecutive cold waves on the geomorphology of the boulder beach cannot be ignored in this study area.Alternating and repeated interactions between these two processes constitute the complete geomorphic evolution of the boulder beach.This study contributes to improved predictions of the morphodynamic response of boulder beaches to future storms,especially large tropical storms,and facilitates better coastal management.
基金The National Natural Science Foundation of China under contract Nos 41930538,42076211 and 42076058the Scientific Research Foundation of the Third Institute of Oceanography,Ministry of Natural Resources under contract Nos 2022017 and 2019006the China Postdoctoral Science Foundation under contract No.2019M652248.
文摘The clay mineralogy of 28 sandy-muddy transitional beach(SMT-Beach)sediments and surrounding mountain river sediments along the coasts of southeastern China was systematically investigated to reveal the sediment source-to-sink process variations of such beaches and their morphological indications.The results show that the clay mineral assemblages of these SMT-Beaches mainly comprise of almost equal illite(~30%),kaolinite(~28%),chlorite(~22%),and smectite(~20%)contents.From the surrounding mountain rivers to the SMT-Beaches,clay mineral assemblages show distinct spatial changes characterized by a large decrease(~40%)in kaolinite,whereas the other three clay minerals present relative increases,especially clear for smectite.The muddy sediment sources of SMT-Beaches inferred from the clay mineralogy are mainly derived from nearby mountain rivers coupled with long-distance transport and penetration of the Changjiang River.The sandy sediments of these beaches are predominantly sourced from nearby mountain rivers,the weathering products of surrounding rocks in both mainland and island environments,and erosion of the“Old Red Sand”and“Red Soil Platform”.However,the sandy sediment sources of the SMT-Beaches are largely reduced because of the remarkable decrease in the river fluvial supply associated with intensive human activities such as dam construction and coastal reclamation.Subsequently,the sandy sections of SMT-Beaches present clear erosion and have revealed by both time series remote sensing images and a compilation of published literature.In contrast,the muddy sediment supply of SMT-Beaches is temporarily stable and relatively constant,resulting in the landward migration of the mudflats with relative transgression or accumulation.These findings highlight that the natural evolution processes of SMT-Beaches have been greatly reshaped by intensive human activities.
基金The National Natural Science Foundation of China under contract Nos 42076211 and 41930538.
文摘The cross-shore variation in wind speeds influenced by beach nourishment,especially the dramatic changes at the nourished berm,is important for understanding the aeolian sand transport processes that occur after beach nourishment,which will contribute to better beach nourishment project design on windy coasts.In this paper,the influencing factors and potential mechanism of wind speed variation at the edge of a nourished berm were studied.Field observations,together with the Duna model,were used to study the cross-shore wind speed distribution for different nourishment schemes.The results show that the nourished berm elevation and beachface slope are the main factors controlling the increase in wind speed at the berm edge.When the upper beach slope is constant,the wind speed at the berm edge has a positive linear correlation with the berm elevation.When the berm elevation remains constant,the wind speed at the berm edge is also proportional to the upper beach slope.Considering the coupling effects of nourished berm elevation and beachface slope,a model for predicting the wind speed amplification rate at the nourished berm edge was established,and the underlying coupling mechanism was illustrated.
基金the Key Project of Provincial Natural Science Research Foundation of Anhui Universities,China(Nos.2022AH050406,2023AH050346)Anhui Province Research Funding for Outstanding Young Talents in Colleges and Universities,China(No.gxyq2022021)+3 种基金the Autonomous Project of Key Laboratory of Green and Precise Synthetic Chemistry and Applications,Ministry of Education(KLGPSCA202307,KLGPSCA202111)the Project of Graduate Innovation Fund(CX2024016)the Laboratory Open Project of Huaibei Normal University(Nos.2023syskf017,2023syskf027)the Industry-University-Research Horizontal Project(Nos.2023340603000039,22100370)forfinancial support.
文摘The N-H methylsulfoxidation of sulfoximines using DMso as a methylsulfinyl source,induced by electrochemistry,has been developed.This method is the first example of an electrochemical reaction in which DMso serves as a methylsulfinyl source.Unlike previous electrochemical reactions involving DMsO as a substrate,which exclusively proceed via radical mechanisms,this reaction follows an S-cation pathway.A wide range of N-methylsulfinyl sulfoximines were successfully obtained.
基金This work was supported by National Natural Science Foundation of China.(No.82170960,81870769,51973243,52173150 and 82201098)Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110379 and 2021A1515010782)the Shenzhen Basic Research Project(JCYJ20190807155801657).
文摘Recent evidence highlights multifaceted biological needs to recapitulate the bone microenvironment for bone regeneration.Neurotization has great potential for realizing multi-system modulations in bone tissue engineering(BTE).However,a neural strategy involving all the key bone repair steps temporally has not yet been reported.In this study,we reported the neural tissue engineering hydrogel-encapsulated Schwann cell-derived exosomes(SC Exo).This sustained-release SC Exo system prominently enhanced bone regeneration by promoting innervation,immunoregulation,vascularization,and osteogenesis in vivo.Moreover,the in vitro results further confirmed that this system significantly induced M2 polarization of macrophages,tube formation of HUVECs,and BMSCs osteogenic differentiation.Furthermore,BMSCs osteogenesis was promoted by upregulating the TGF-β1/SMAD2/3 signaling pathway.In summary,a novel cell-free and easily prepared SC Exo neural engineering was successfully developed to promote bone regeneration by orchestrating the entire bone healing microenvironment,which may provide a new strategy for tissue engineering and clinical treatment of bone defects.
基金This work was supported by the National Natural Science Foundation of China(grant nos.51775517 and 51905493)the Henan Provincial Science and Technology Research Project(nos.212102210074,202102210070,and 202102210396).
文摘Background:Digital twin requires virtual reality mapping and optimization iteration between physical devices and virtual models.The mechanical movement data collection of physical equipment is essential for the implementation of accurate virtual and physical synchronization in a digital twin environment.However,the traditional approach relying on PLC(programmable logic control)fails to collect various mechanical motion state data.Additionally,few investigations have used machine visions for the virtual and physical synchronization of equipment.Thus,this paper presents a mechanical movement data acquisition method based on multilayer neural networks and machine vision.Methods:Firstly,various visual marks with different colors and shapes are designed for marking physical devices.Secondly,a recognition method based on the Hough transform and histogram feature is proposed to realize the recognition of shape and color features respectively.Then,the multilayer neural network model is introduced in the visual mark location.The neural network is trained by the dropout algorithm to realize the tracking and location of the visual mark.To test the proposed method,1000 samples were selected.Results:The experiment results shows that when the size of the visual mark is larger than 6mm,the recognition success rate of the recognition algorithm can reach more than 95%.In the actual operation environment with multiple cameras,the identification points can be located more accurately.Moreover,the camera calibration process of binocular and multi-eye vision can be simplified by the multilayer neural networks.Conclusions:This study proposes an effective method in the collection of mechanical motion data of physical equipment in a digital twin environment. Further studies are needed to perceive posture and shape data of physical entities under the multi-camera redundant shooting.
