This study employs a linear inversion algorithm to retrieve volume emission rates(VERs)of molecular O_(2) nightglow at 1.27μm,utilizing Limb-Viewed spectra obtained from the SCanning Imaging Absorption spectroMeter f...This study employs a linear inversion algorithm to retrieve volume emission rates(VERs)of molecular O_(2) nightglow at 1.27μm,utilizing Limb-Viewed spectra obtained from the SCanning Imaging Absorption spectroMeter for Atmospheric for CHartographY(SCIAMACHY)payload on board the Envisat satellite.The retrieved results are compared with VERs data from the SABER payload on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics(TIMED)satellite,exhibiting consistency.This will help to facilitate accurate revelation of spatial distribution and periodic variation in O_(2) nightglow.VERs are extracted monthly within the altitude range of 75-110 km from 2002 to 2012,yielding a climatology of spatial and temporal distributions.The meridional structure exhibits two maxima,at the equator and at 45°N.Between August and October,the VERs exhibit a meridional bimodal structure,with the weaker one above the equator and the stronger one above 45°N.In April,the VERs reach their annual maximum.Additionally,harmonic analysis reveals significant temporal variations on different scales.The emission shows characteristics of annual and semi-annual variation,and a non-linear long-term trend associated with solar cycle activity.展开更多
Amyotrophic lateral sclerosis(ALS)is a progressive neurodegenerative disease affecting both upper and lower motor neurons(MNs)with large unmet medical needs.Multiple pathological mechanisms are considered to contribut...Amyotrophic lateral sclerosis(ALS)is a progressive neurodegenerative disease affecting both upper and lower motor neurons(MNs)with large unmet medical needs.Multiple pathological mechanisms are considered to contribute to the progression of ALS,including neuronal oxidative stress and mitochondrial dysfunction.Honokiol(HNK)has been reported to exert therapeutic effects in several neurologic disease models including ischemia stroke,Alzheimer’s disease and Parkinson’s disease.Here we found that honokiol also exhibited protective effects in ALS disease models both in vitro and in vivo.Honokiol improved the viability of NSC-34 motor neuron-like cells that expressed the mutant G93A SOD1 proteins(SOD1-G93A cells for short).Mechanistical studies revealed that honokiol alleviated cellular oxidative stress by enhancing glutathione(GSH)synthesis and activating the nuclear factor erythroid 2-related factor 2(NRF2)-antioxidant response element(ARE)pathway.Also,honokiol improved both mitochondrial function and morphology via fine-tuning mitochondrial dynamics in SOD1-G93A cells.Importantly,honokiol extended the lifespan of the SOD1-G93A transgenic mice and improved the motor function.The improvement of antioxidant capacity and mitochondrial function was further confirmed in the spinal cord and gastrocnemius muscle in mice.Overall,honokiol showed promising preclinical potential as a multiple target drug for ALS treatment.展开更多
LZ91 Mg-Li alloy plates with three types of initial texture were rolled by 70%reduction at both room temperature and 200℃to explore the rolling texture formation ofα-Mg phase.The results showed that the rolling text...LZ91 Mg-Li alloy plates with three types of initial texture were rolled by 70%reduction at both room temperature and 200℃to explore the rolling texture formation ofα-Mg phase.The results showed that the rolling texture is largely affected by the initial texture.All the samples exhibited two main texture components as RD-split double peaks texture and TD-split double peaks texture after large strain rolling.The intensity of the two texture components was strongly influenced by the initial orientation and rolling temperature.Extension twinning altered the large-split non-basal orientation to a near basal one at low rolling strain.The basal orientation induced by twinning is unstable,which finally transmitted to the RD-split texture.The strong TD-split texture formed due to slip-induced orientation transition from its initial orientation.The competition between prismatic <a>and basal slip determined the intensity and tilt angle of the TD-split texture.By increasing the rolling temperature,the TD-split texture component was enhanced in all three samples.Limitation of extension twinning behavior and the promotion of prismatic slip at elevated temperature are the main reasons for the difference in hot and cold rolling texture.展开更多
Artificial ageing above 165℃directly after quenching induces the formation of^50 nm wide precipitatefree zone(PFZ)and^100 nm wide precipitate-sparse zone(PSZ)consisting of coarse precipitates with a gradient in size ...Artificial ageing above 165℃directly after quenching induces the formation of^50 nm wide precipitatefree zone(PFZ)and^100 nm wide precipitate-sparse zone(PSZ)consisting of coarse precipitates with a gradient in size and density toward the grain center in a commercial Al-Zn-Mg-Cu alloy.With the grain size decreasing,the fraction of PFZ and PSZ in a grain becomes larger and could even occupy the entire volume of the grain.This undesirable microstructure near the grain boundary is mitigated substantially by natural pre-ageing,leading to an exceptional enhancement of the age hardening potential at elevated temperatures.Natural ageing could fundamentally alter the precipitation near grain boundary,and is a promising method to optimize the precipitation hardening in high strength aluminum alloys with unconventionally small grains.展开更多
Preheating is the first step for thermal-mechanical processing of the materials. Several preheating schedules were designed based on industrial manufacturing to explore their effect on the microstructure and mechanica...Preheating is the first step for thermal-mechanical processing of the materials. Several preheating schedules were designed based on industrial manufacturing to explore their effect on the microstructure and mechanical properties of AA2099 Al-Li alloy during the following hot rolling. The results show that the mechanical properties of as-rolled sheets are quite sensitive to preheating. Various types of secondary phases, including δ', T1 and T2 phases, were precipitated during the heating process. The difference among precipitates is the main reason to induce the variation of mechanical properties for as-rolled sheets. A rapid heating rate gave rise to the precipitation of δ' phase, which largely promoted yield stress and ultimate tensile strength in as-rolled sheets. T1 phase was more favorable in the preheating with a holding period at 150–250 °C, which caused a moderated strain hardening behavior. Precipitates formed during preheating induced different slip behaviors in the following deformation. The coexistence of T1 and δ' phase could restrict planar slip, which inhibited the formation of the shear band. The difference in the activity of non-octahedral slips and planar slips determined the strain hardening effect, which should be the reason for the variation of mechanical properties of as-rolled sheets.展开更多
For aeronautical composite materials,the appearance of internal delamination has a fatal impact on their mechanical properties and may even seriously threaten aircraft flight safety.In this study,the effect of interna...For aeronautical composite materials,the appearance of internal delamination has a fatal impact on their mechanical properties and may even seriously threaten aircraft flight safety.In this study,the effect of internal delamination damage with different sizes and depths on the tensile strength of aeronautical composites was investigated.Firstly,based on carbon-fiber-reinforced composites commonly used in aircraft,laminate specimens with internal delamination damages of different depths and diameters were fabricated,and tensile tests of composite materials were carried out.Then,the finite element model for the carbon-fiber-reinforced laminate specimens was established,and the validity of the model was verified by comparing its simulation results with the experimental data.Furthermore,by changing the geometric parameters of the internal delamination damage model,the influence of delamination damage on the tensile strength of carbon-fiber-reinforced composites was analyzed and summarized.The results show that,on the one hand,for the internal delamination damages of the same area,the closer is the delamination damage to the surface layer,the lower is the tensile strength.In particular,the closer is the delamination damage to the surface layer,the greater is the decrease in tensile strength,which exhibits an obvious nonlinear relationship.On the other hand,for the internal delamination defects of the same depth,the difference in delamination area has little effect on the tensile strength.This law provides a reference for the damage detection and maintenance focus of aeronautical composite structures,which is of great significance to ensure the safe use of aeronautical composites.展开更多
基金supported by the National Key R&D program of China(2021YFE0110200)the Project of Stable Support for Youth Team in Basic Research Field,CAS(YSBR-018)+3 种基金the National Natural Science Foundation of China(41831073,42174196 and 42174212)the Chinese Meridian Projectthe Specialized Research Fund for State Key Laboratoriesthe International Partnership Program of Chinese Academy of Sciences.Grant No.183311KYSB20200003.
文摘This study employs a linear inversion algorithm to retrieve volume emission rates(VERs)of molecular O_(2) nightglow at 1.27μm,utilizing Limb-Viewed spectra obtained from the SCanning Imaging Absorption spectroMeter for Atmospheric for CHartographY(SCIAMACHY)payload on board the Envisat satellite.The retrieved results are compared with VERs data from the SABER payload on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics(TIMED)satellite,exhibiting consistency.This will help to facilitate accurate revelation of spatial distribution and periodic variation in O_(2) nightglow.VERs are extracted monthly within the altitude range of 75-110 km from 2002 to 2012,yielding a climatology of spatial and temporal distributions.The meridional structure exhibits two maxima,at the equator and at 45°N.Between August and October,the VERs exhibit a meridional bimodal structure,with the weaker one above the equator and the stronger one above 45°N.In April,the VERs reach their annual maximum.Additionally,harmonic analysis reveals significant temporal variations on different scales.The emission shows characteristics of annual and semi-annual variation,and a non-linear long-term trend associated with solar cycle activity.
基金supported by the National Natural Science Foundation of China(21871079,21501052)the Outstanding Youth Project of Natural Science Foundation of Heilongjiang Province(YQ2019B006)~~
基金supported by the grants from National Natural Science Foundation of China(Nos.82073835 and 81872855)National Key R&D Program of China(No.2019YFC1708901)+2 种基金CAMS Innovation Fund for Medical Sciences(No.2021-I2M-1028)Beijing Key Laboratory of New Drug Mechanisms and Pharmacological Evaluation Study(BZ0150,China)Disciplines construction project(201920200802,China)。
文摘Amyotrophic lateral sclerosis(ALS)is a progressive neurodegenerative disease affecting both upper and lower motor neurons(MNs)with large unmet medical needs.Multiple pathological mechanisms are considered to contribute to the progression of ALS,including neuronal oxidative stress and mitochondrial dysfunction.Honokiol(HNK)has been reported to exert therapeutic effects in several neurologic disease models including ischemia stroke,Alzheimer’s disease and Parkinson’s disease.Here we found that honokiol also exhibited protective effects in ALS disease models both in vitro and in vivo.Honokiol improved the viability of NSC-34 motor neuron-like cells that expressed the mutant G93A SOD1 proteins(SOD1-G93A cells for short).Mechanistical studies revealed that honokiol alleviated cellular oxidative stress by enhancing glutathione(GSH)synthesis and activating the nuclear factor erythroid 2-related factor 2(NRF2)-antioxidant response element(ARE)pathway.Also,honokiol improved both mitochondrial function and morphology via fine-tuning mitochondrial dynamics in SOD1-G93A cells.Importantly,honokiol extended the lifespan of the SOD1-G93A transgenic mice and improved the motor function.The improvement of antioxidant capacity and mitochondrial function was further confirmed in the spinal cord and gastrocnemius muscle in mice.Overall,honokiol showed promising preclinical potential as a multiple target drug for ALS treatment.
基金supported by Research Program of Chongqing Municipal Education Commission(KJQN201901127)University Innovation Research Group of Chongqing(CXQT20023)+2 种基金Natural Science Foundation of Chongqing(cstc2021ycjh-bgzxm0184)support by the Research Program of Chongqing Municipal Education Commission(KJQN202201151)National Natural Science Foundation of China(52201107).
文摘LZ91 Mg-Li alloy plates with three types of initial texture were rolled by 70%reduction at both room temperature and 200℃to explore the rolling texture formation ofα-Mg phase.The results showed that the rolling texture is largely affected by the initial texture.All the samples exhibited two main texture components as RD-split double peaks texture and TD-split double peaks texture after large strain rolling.The intensity of the two texture components was strongly influenced by the initial orientation and rolling temperature.Extension twinning altered the large-split non-basal orientation to a near basal one at low rolling strain.The basal orientation induced by twinning is unstable,which finally transmitted to the RD-split texture.The strong TD-split texture formed due to slip-induced orientation transition from its initial orientation.The competition between prismatic <a>and basal slip determined the intensity and tilt angle of the TD-split texture.By increasing the rolling temperature,the TD-split texture component was enhanced in all three samples.Limitation of extension twinning behavior and the promotion of prismatic slip at elevated temperature are the main reasons for the difference in hot and cold rolling texture.
基金the National Natural Science Foundation of China(Nos.51601060,51675538 and 11872380)the Natural Science Foundation of Hunan Province(No.2018JJ3655)+3 种基金the National Key R&D Program of China(No.2017YFB0306300)the Innovation-driven Plan in Central South University(No.2015CX002)the Science and Technology Plan in Hunan Province(No.2016RS2015)the Fundamental Research Funds for the Central Universities of Central South University(No.2018zzts154)。
文摘Artificial ageing above 165℃directly after quenching induces the formation of^50 nm wide precipitatefree zone(PFZ)and^100 nm wide precipitate-sparse zone(PSZ)consisting of coarse precipitates with a gradient in size and density toward the grain center in a commercial Al-Zn-Mg-Cu alloy.With the grain size decreasing,the fraction of PFZ and PSZ in a grain becomes larger and could even occupy the entire volume of the grain.This undesirable microstructure near the grain boundary is mitigated substantially by natural pre-ageing,leading to an exceptional enhancement of the age hardening potential at elevated temperatures.Natural ageing could fundamentally alter the precipitation near grain boundary,and is a promising method to optimize the precipitation hardening in high strength aluminum alloys with unconventionally small grains.
基金financially supported by the National Natural Science Foundation of China (Grant No. 51871038)the Chongqing Key Project of Technology Innovation and Application Development (Grant No. cstc2019jscx-mbdx X0025)the support from the University Innovation Research Group of Chongqing (Grant No. CXQT20023)。
文摘Preheating is the first step for thermal-mechanical processing of the materials. Several preheating schedules were designed based on industrial manufacturing to explore their effect on the microstructure and mechanical properties of AA2099 Al-Li alloy during the following hot rolling. The results show that the mechanical properties of as-rolled sheets are quite sensitive to preheating. Various types of secondary phases, including δ', T1 and T2 phases, were precipitated during the heating process. The difference among precipitates is the main reason to induce the variation of mechanical properties for as-rolled sheets. A rapid heating rate gave rise to the precipitation of δ' phase, which largely promoted yield stress and ultimate tensile strength in as-rolled sheets. T1 phase was more favorable in the preheating with a holding period at 150–250 °C, which caused a moderated strain hardening behavior. Precipitates formed during preheating induced different slip behaviors in the following deformation. The coexistence of T1 and δ' phase could restrict planar slip, which inhibited the formation of the shear band. The difference in the activity of non-octahedral slips and planar slips determined the strain hardening effect, which should be the reason for the variation of mechanical properties of as-rolled sheets.
文摘For aeronautical composite materials,the appearance of internal delamination has a fatal impact on their mechanical properties and may even seriously threaten aircraft flight safety.In this study,the effect of internal delamination damage with different sizes and depths on the tensile strength of aeronautical composites was investigated.Firstly,based on carbon-fiber-reinforced composites commonly used in aircraft,laminate specimens with internal delamination damages of different depths and diameters were fabricated,and tensile tests of composite materials were carried out.Then,the finite element model for the carbon-fiber-reinforced laminate specimens was established,and the validity of the model was verified by comparing its simulation results with the experimental data.Furthermore,by changing the geometric parameters of the internal delamination damage model,the influence of delamination damage on the tensile strength of carbon-fiber-reinforced composites was analyzed and summarized.The results show that,on the one hand,for the internal delamination damages of the same area,the closer is the delamination damage to the surface layer,the lower is the tensile strength.In particular,the closer is the delamination damage to the surface layer,the greater is the decrease in tensile strength,which exhibits an obvious nonlinear relationship.On the other hand,for the internal delamination defects of the same depth,the difference in delamination area has little effect on the tensile strength.This law provides a reference for the damage detection and maintenance focus of aeronautical composite structures,which is of great significance to ensure the safe use of aeronautical composites.