We propose a method to quantitatively characterize the fine phase transition processes of Li^(+)/Er^(3+):BaTiO_(3)(BLET)ferroelectric materials by observing fluorescence wavelength shift.A lithium and erbium co-doped ...We propose a method to quantitatively characterize the fine phase transition processes of Li^(+)/Er^(3+):BaTiO_(3)(BLET)ferroelectric materials by observing fluorescence wavelength shift.A lithium and erbium co-doped barium titanate ferroelectric ceramic was fabricated and the down-conversion infrared fluorescence spectra of the transition^(4)I13/2→^(4)I15/2 were measured as a function of temperature.The three structural phase transition processes,namely rhombohedral-orthorhombic,orthorhombic-tetragonal,and tetragonal-cubic transformations,determined by X-ray diffraction results are accompanied by corresponding changes in the position of the fluorescence peaks,yielding an exact consistency.This contactless,non-destructive and spatially-resolved fluorescence method provides a localized quantitative analysis for the phase transition processes of BLET ceramics.As this method is based on the fluorescence peak wavelength dependence on the crystal environment,it may potentially be used to characterize the phase transitions in other ferroelectric materials.展开更多
Autophagy has been extensively studied and occurs in many biological settings.However,a question remains as to whether ischemia enhances Beclin-1/LC3-II-dependent macroautophagy in vascular endothelial cells,as has be...Autophagy has been extensively studied and occurs in many biological settings.However,a question remains as to whether ischemia enhances Beclin-1/LC3-II-dependent macroautophagy in vascular endothelial cells,as has been previously thought.Furthermore,the effect of the level of autophagy on cell or skin flap survival still requires elucidation.We created a lethal ischemia model in human umbilical vascular endothelial cells(HUVECs),performed quantitative proteomics and bioinformatics analyses,and verified the autophagic status and effect both in vitro and in vivo.The significantly upregulated proteins encoded by autophagy-related genes(ATGs)included ATG2A,ATG3,ATG4B,ATG5,ATG7,ATG9A,ATG12,ATG16,and ATG101.The significantly enhanced lysosomal proteins were cathepsin B,cathepsin D,lysosome-associated membrane protein 1(LAMP1),and LAMP2.However,the differentially expressed proteins excluded Beclin-1,microtubule-associated protein light chain 3(LC3)-I,and LC3-II.Western blot analyses verified that the protein expression levels of Beclin-1,LC3-I,and LC3-II were neither upregulated nor downregulated in ischemia-challenged HUVECs.The autophagic status was not enhanced by rapamycin in ischemic HUVECs but appeared to be inhibited by chloroquine.Our in vivo study on rats showed that a downregulation in autophagic status jeopardized skin flap survival.In conclusion,Ischemia neither enhanced nor inhibited Beclin-1/LC3-II-dependent canonical macroautophagy both in vitro and in vivo,in contradiction to previous studies.An appropriate autophagic homeostasis can minimize cell or skin flap damage.展开更多
Titania nanotubes(TNT)generated on titanium implant are emerged as important modification technique to facilitate bone regeneration.Mesenchymal stem cells(MSCs)-derived exosomes are membrane bound extracellular vesicl...Titania nanotubes(TNT)generated on titanium implant are emerged as important modification technique to facilitate bone regeneration.Mesenchymal stem cells(MSCs)-derived exosomes are membrane bound extracellular vesicles(EVs),which play an important role in tissue regeneration.The objective of this study was to generate an EVs hybrid TNT aiming at regulating inflammation,MSCs recruitment and osteogenesis.We isolated EVs from MSCs(MSCs EVs)and 3-day osteogenically differentiated MSCs(3d EVs).MSC EVs and 3d EVs exhibited round morphology under TEM,which also showed robust internalization by human bone marrow derived MSCs(hBMSCs).Next,we fabricated 3d EVs/MSC EVs hybrid TNT.When inflammatory macrophages were co-cultured with EVs hybrid TNT,the gene and protein expression of inflammatory cytokine were significantly reduced.Macrophage morphology was also examined by confocal laser scanning microscopy(CLSM)and scanning electron microscopy(SEM).Further migratory ability study using hBMSCs indicated significant enhancement of MSCs migration in EVs hybrid TNT.In addition,we further demonstrated significant increase of osteogenic differentiation of hBMSCs in EVs hybrid TNT.This study suggests that EVs hybrid TNT may serve as a viable therapeutic approach to enhance osteogenesis and bone regeneration.展开更多
Pedestrian safety evacuation in aircraft cabins has been a challenging problem because of the aircraft’s unique characteristics,such as the diversity of passengers and the restricted evacuation environment.It is diff...Pedestrian safety evacuation in aircraft cabins has been a challenging problem because of the aircraft’s unique characteristics,such as the diversity of passengers and the restricted evacuation environment.It is difficult to reproduce evacuation activities in aircraft cabin due to safety concerns and cost constraints.To fill this gap,an improved cellular automaton model of crowd evacuation for aircraft cabin is established by incorporating the characteristics of cabin space structures and passenger attributes.Passengers are divided into healthy individual passengers and disabled-healthy group passengers,whose movement mechanisms are quantified.Based on the constructed model,simulation experiments are conducted using the configuration cabin layout of B737-800 as an example.The results show that the evacuation time is prolonged with increased passenger density and the number of disabled passengers.Moreover,the overall evacuation time is insignificantly affected by whether disabled-healthy group passengers’seats are close to the aisle or window,and the evacuation efficiency is best when their seats are evenly distributed in the cabin.The evacuation time is the shortest when all cabin doors are open,and pedestrians are evacuated the slowest when the central emergency doors are closed.This study pro-vides valuable insights into effective strategies for pedestrian evacuation and crowd emergency management of civil aircraft.展开更多
Synoptic meteorology is a branch of meteorology that uses synoptic weather observations and charts for the diagnosis,study,and forecasting of weather.Weather refers to the specific state of the atmosphere near the Ea...Synoptic meteorology is a branch of meteorology that uses synoptic weather observations and charts for the diagnosis,study,and forecasting of weather.Weather refers to the specific state of the atmosphere near the Earth’s surface during a short period of time.The spatial distribution of meteorological elements in the atmosphere can be represented by a variety of transient weather phenomena,which are caused by weather systems of different spatial and temporal scales.Weather is closely related to people’s life,and its development and evolution have always been the focus of atmospheric scientific research and operation.The development of synoptic meteorology is closely related to the development of observation systems,dynamical theories and numerical models.In China,observation networks have been built since the early 1950 s.Up to now,a comprehensive meteorological observation systembased on ground,air and space has been established.In particular,the development of a new generation of dense radar networks,the development of the Fengyun satellite series and the implementation of a series of large field experiments have brought our understanding of weather from large-scale environment to thermal dynamics,cloud microphysical structure and evolution characteristics of meso and micro-scale weather systems.The development of observation has also promoted the development of theory,numerical model and simulation.In the early days,China mainly used foreign numerical models.Lately,China has developed numerical model systems with independent intellectual property rights.Based on the results of high-resolution numerical simulations,in-depth understanding of the initiation and evolution mechanism and predictability of weather at different scales has been obtained.Synoptic meteorology has gradually changed from an initially independent development to a multidisciplinary approach,and the interaction between weather and the change of climate and environment has become a hot and frontier topic in atmospheric science.This paper reviews the important scientific and technological achievements made in China over the past 70 years in the fields of synoptic meteorology based on the literatures in China and abroad,from six aspects respectively including atmospheric dynamics,synoptic-scale weather,typhoon and tropical weather,severe convective weather,numerical weather prediction and data assimilation,weather and climate,atmospheric physics and atmospheric environment.展开更多
Dynamic ultra-high pressure homogenization(UHPH)is a novel high-pressure processing technique.In this study,the effects of dynamic UHPH on the structure and functional properties of casein were systematically investig...Dynamic ultra-high pressure homogenization(UHPH)is a novel high-pressure processing technique.In this study,the effects of dynamic UHPH on the structure and functional properties of casein were systematically investigated.It was found that the functional properties of casein changed with dynamic UHPH treatment,and the treatment at 150 MPa could significantly improve casein aqueous solubility,foaming and emulsifying properties.These functional improvements could be attributed to its structural changes,since the dynamic UHPH treatment could change the secondary structure,promote the interchange reaction between the disulfide bond and the sulfhydryl group,and increase the surface hydrophobicity.The obtained results could broaden the application of casein and provide ideas for the non-thermal processing of proteins.展开更多
Evacuation signs are a key factor in the effectiveness of occupants'urgent escape from buildings.Different sign features may have disparate impacts on individual and crowd behavior.This study aims to quantitativel...Evacuation signs are a key factor in the effectiveness of occupants'urgent escape from buildings.Different sign features may have disparate impacts on individual and crowd behavior.This study aims to quantitatively inves-tigate the effectiveness of building evacuation signs with different features during pedestrian evacuation using eye-tracking devices.Ten experiments were conducted in a building in T-junction scenarios,and four sets of features related to evacuation signs(color,position,graphics,and flashing)were considered.SMI BeGaze was used to analyze the eye movements of the occupants.The fixation duration of the evacuees and the ratio of signs detected and followed were quantitatively derived and compared for each experiment.The results show that it is easier for evacuees to detect signs at a low sightline,and signs posted at that level of sight can provide better guidance.When signs are posted high up,red signs are easier to detect than green signs.Most evacuees prefer to follow the evacuation signs once they detect them;however,there is no significant difference in the effect of what is posted on the evacuation signs,such as a running man or an arrow.Conversely,flashing of signs is highly helpful in influencing evacuees'behavior,but flashing is not helpful in detecting signs.More importantly,red signs with a running man graphic located in a low position have the best guiding effects on evacuees.The fixa-tion behaviors of evacuees vary according to sign features,particularly in regard to flashing and color.Evacuees stare longer at twinkling signs.Differences in the colors and positions of signs result in significantly different perceptual behaviors among evacuees.Our findings are useful for building designers and provide guidance for developing effective evacuation strategies.展开更多
基金supported in part by the National Key Basic Research Program of China[grant no.2013CB632900]the National Natural Science Foundation of China(NSFC)[grant no.11304061]。
文摘We propose a method to quantitatively characterize the fine phase transition processes of Li^(+)/Er^(3+):BaTiO_(3)(BLET)ferroelectric materials by observing fluorescence wavelength shift.A lithium and erbium co-doped barium titanate ferroelectric ceramic was fabricated and the down-conversion infrared fluorescence spectra of the transition^(4)I13/2→^(4)I15/2 were measured as a function of temperature.The three structural phase transition processes,namely rhombohedral-orthorhombic,orthorhombic-tetragonal,and tetragonal-cubic transformations,determined by X-ray diffraction results are accompanied by corresponding changes in the position of the fluorescence peaks,yielding an exact consistency.This contactless,non-destructive and spatially-resolved fluorescence method provides a localized quantitative analysis for the phase transition processes of BLET ceramics.As this method is based on the fluorescence peak wavelength dependence on the crystal environment,it may potentially be used to characterize the phase transitions in other ferroelectric materials.
基金This work was supported by the National Natural Science Foundation of China(No.81400493)Scientific and Technological Research Program of Chongqing Municipal Education Commission(No.KJQN20200429)Joint Medical Research Project by Chongqing Health Commission and Natural Science Foundation of Chongqing(No.2020GDRC008).
文摘Autophagy has been extensively studied and occurs in many biological settings.However,a question remains as to whether ischemia enhances Beclin-1/LC3-II-dependent macroautophagy in vascular endothelial cells,as has been previously thought.Furthermore,the effect of the level of autophagy on cell or skin flap survival still requires elucidation.We created a lethal ischemia model in human umbilical vascular endothelial cells(HUVECs),performed quantitative proteomics and bioinformatics analyses,and verified the autophagic status and effect both in vitro and in vivo.The significantly upregulated proteins encoded by autophagy-related genes(ATGs)included ATG2A,ATG3,ATG4B,ATG5,ATG7,ATG9A,ATG12,ATG16,and ATG101.The significantly enhanced lysosomal proteins were cathepsin B,cathepsin D,lysosome-associated membrane protein 1(LAMP1),and LAMP2.However,the differentially expressed proteins excluded Beclin-1,microtubule-associated protein light chain 3(LC3)-I,and LC3-II.Western blot analyses verified that the protein expression levels of Beclin-1,LC3-I,and LC3-II were neither upregulated nor downregulated in ischemia-challenged HUVECs.The autophagic status was not enhanced by rapamycin in ischemic HUVECs but appeared to be inhibited by chloroquine.Our in vivo study on rats showed that a downregulation in autophagic status jeopardized skin flap survival.In conclusion,Ischemia neither enhanced nor inhibited Beclin-1/LC3-II-dependent canonical macroautophagy both in vitro and in vivo,in contradiction to previous studies.An appropriate autophagic homeostasis can minimize cell or skin flap damage.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.31960209 and 31760266)the Scientific Innovation Foundation for Returned Overseas Chinese Scholars of Guizhou Province(Grant No.2018-07)+2 种基金Guizhou Science and Technology Fund Project(Grant No.Qian Ke He Ji Chu[2020]1Y093)Qian Wei Ji Ban Han(Grant No.2017-24)Academic New Seedlings Cultivation and Innovation Exploration Project of Zunyi Medical University(Grant No.Qian Ke He Ping Tai Ren Cai[2017]5733-015).
文摘Titania nanotubes(TNT)generated on titanium implant are emerged as important modification technique to facilitate bone regeneration.Mesenchymal stem cells(MSCs)-derived exosomes are membrane bound extracellular vesicles(EVs),which play an important role in tissue regeneration.The objective of this study was to generate an EVs hybrid TNT aiming at regulating inflammation,MSCs recruitment and osteogenesis.We isolated EVs from MSCs(MSCs EVs)and 3-day osteogenically differentiated MSCs(3d EVs).MSC EVs and 3d EVs exhibited round morphology under TEM,which also showed robust internalization by human bone marrow derived MSCs(hBMSCs).Next,we fabricated 3d EVs/MSC EVs hybrid TNT.When inflammatory macrophages were co-cultured with EVs hybrid TNT,the gene and protein expression of inflammatory cytokine were significantly reduced.Macrophage morphology was also examined by confocal laser scanning microscopy(CLSM)and scanning electron microscopy(SEM).Further migratory ability study using hBMSCs indicated significant enhancement of MSCs migration in EVs hybrid TNT.In addition,we further demonstrated significant increase of osteogenic differentiation of hBMSCs in EVs hybrid TNT.This study suggests that EVs hybrid TNT may serve as a viable therapeutic approach to enhance osteogenesis and bone regeneration.
基金supported by Civil Aircraft Fire Science and Safety Engineering Key Laboratory of Sichuan Province(MZ2022KF07)the National Natural Science Foundation of China(Grant No22042333)the Fundamental Research Funds for the Central Universities(2021III053JC,2021III052JC).
文摘Pedestrian safety evacuation in aircraft cabins has been a challenging problem because of the aircraft’s unique characteristics,such as the diversity of passengers and the restricted evacuation environment.It is difficult to reproduce evacuation activities in aircraft cabin due to safety concerns and cost constraints.To fill this gap,an improved cellular automaton model of crowd evacuation for aircraft cabin is established by incorporating the characteristics of cabin space structures and passenger attributes.Passengers are divided into healthy individual passengers and disabled-healthy group passengers,whose movement mechanisms are quantified.Based on the constructed model,simulation experiments are conducted using the configuration cabin layout of B737-800 as an example.The results show that the evacuation time is prolonged with increased passenger density and the number of disabled passengers.Moreover,the overall evacuation time is insignificantly affected by whether disabled-healthy group passengers’seats are close to the aisle or window,and the evacuation efficiency is best when their seats are evenly distributed in the cabin.The evacuation time is the shortest when all cabin doors are open,and pedestrians are evacuated the slowest when the central emergency doors are closed.This study pro-vides valuable insights into effective strategies for pedestrian evacuation and crowd emergency management of civil aircraft.
基金supported by the National Natural Science Foundation of China (Grant No. 41425018)the National Key Research and Development Program of China (Grant No. 2017YFC1501601)+3 种基金the National Natural Science Foundation of China (Grant No. 41675045)the National Key Research and Development Program of China (Grant No. 2017YFC1501904)the National Natural Science Foundation of China (Grant Nos. 41875066, 41675108 & 41875051)the Special Program on the Monitoring, Warning and Prevention of Major Natural Disasters (Grant No. 2018YFC1506702)
文摘Synoptic meteorology is a branch of meteorology that uses synoptic weather observations and charts for the diagnosis,study,and forecasting of weather.Weather refers to the specific state of the atmosphere near the Earth’s surface during a short period of time.The spatial distribution of meteorological elements in the atmosphere can be represented by a variety of transient weather phenomena,which are caused by weather systems of different spatial and temporal scales.Weather is closely related to people’s life,and its development and evolution have always been the focus of atmospheric scientific research and operation.The development of synoptic meteorology is closely related to the development of observation systems,dynamical theories and numerical models.In China,observation networks have been built since the early 1950 s.Up to now,a comprehensive meteorological observation systembased on ground,air and space has been established.In particular,the development of a new generation of dense radar networks,the development of the Fengyun satellite series and the implementation of a series of large field experiments have brought our understanding of weather from large-scale environment to thermal dynamics,cloud microphysical structure and evolution characteristics of meso and micro-scale weather systems.The development of observation has also promoted the development of theory,numerical model and simulation.In the early days,China mainly used foreign numerical models.Lately,China has developed numerical model systems with independent intellectual property rights.Based on the results of high-resolution numerical simulations,in-depth understanding of the initiation and evolution mechanism and predictability of weather at different scales has been obtained.Synoptic meteorology has gradually changed from an initially independent development to a multidisciplinary approach,and the interaction between weather and the change of climate and environment has become a hot and frontier topic in atmospheric science.This paper reviews the important scientific and technological achievements made in China over the past 70 years in the fields of synoptic meteorology based on the literatures in China and abroad,from six aspects respectively including atmospheric dynamics,synoptic-scale weather,typhoon and tropical weather,severe convective weather,numerical weather prediction and data assimilation,weather and climate,atmospheric physics and atmospheric environment.
基金This research was supported by the National Natural Science Foundation of China(No.31571912)the Major Science and Technology Project in Henan(No.161100110600).
文摘Dynamic ultra-high pressure homogenization(UHPH)is a novel high-pressure processing technique.In this study,the effects of dynamic UHPH on the structure and functional properties of casein were systematically investigated.It was found that the functional properties of casein changed with dynamic UHPH treatment,and the treatment at 150 MPa could significantly improve casein aqueous solubility,foaming and emulsifying properties.These functional improvements could be attributed to its structural changes,since the dynamic UHPH treatment could change the secondary structure,promote the interchange reaction between the disulfide bond and the sulfhydryl group,and increase the surface hydrophobicity.The obtained results could broaden the application of casein and provide ideas for the non-thermal processing of proteins.
基金supported by National Natural Science Foundation of China(Grant No.72274208,71904194 and 52204233),Basic Research Foundation of People's Public Security University of China(2022JKF02010)and Public Security Behavior Science and Engineering Action Project of People's Public Security University of China(2022KXGCKJ02).
文摘Evacuation signs are a key factor in the effectiveness of occupants'urgent escape from buildings.Different sign features may have disparate impacts on individual and crowd behavior.This study aims to quantitatively inves-tigate the effectiveness of building evacuation signs with different features during pedestrian evacuation using eye-tracking devices.Ten experiments were conducted in a building in T-junction scenarios,and four sets of features related to evacuation signs(color,position,graphics,and flashing)were considered.SMI BeGaze was used to analyze the eye movements of the occupants.The fixation duration of the evacuees and the ratio of signs detected and followed were quantitatively derived and compared for each experiment.The results show that it is easier for evacuees to detect signs at a low sightline,and signs posted at that level of sight can provide better guidance.When signs are posted high up,red signs are easier to detect than green signs.Most evacuees prefer to follow the evacuation signs once they detect them;however,there is no significant difference in the effect of what is posted on the evacuation signs,such as a running man or an arrow.Conversely,flashing of signs is highly helpful in influencing evacuees'behavior,but flashing is not helpful in detecting signs.More importantly,red signs with a running man graphic located in a low position have the best guiding effects on evacuees.The fixa-tion behaviors of evacuees vary according to sign features,particularly in regard to flashing and color.Evacuees stare longer at twinkling signs.Differences in the colors and positions of signs result in significantly different perceptual behaviors among evacuees.Our findings are useful for building designers and provide guidance for developing effective evacuation strategies.
