The rise in urbanization has increasingly restricted access to natural environments,posing substantial risks to the physical and mental health of urban populations,including university students and other high-stress g...The rise in urbanization has increasingly restricted access to natural environments,posing substantial risks to the physical and mental health of urban populations,including university students and other high-stress groups.This study examines the comparative effects of outdoor forest meditation(OFM)and indoor nature meditation(INM)in simulated nature environments(SNEs)on the physiological and psychological health of university students.A pretestposttest repeated measures design was employed,with 40students participating in three replicated OFM sessions and three identical INM sessions across varied SNE settings.Key physiological metrics,including heart rate(HR),blood pressure(BP),and salivary amylase concentration(SAC),were measured before and after each session.Psychological well-being was assessed using the Perceived Stress Scale-10(PSS-10)and Profile of Mood States(POMS).Results revealed significant reductions(p<0.05)in most post-intervention outcomes,except in the second indoor session across physiologic al and psychologic al responses,while multi-sensory INM sessions produced comparable benefits.Notably,SNEs with enhanced sensory components were effective,though slightly less impactful than OFM.These findings suggest that both OFM in nature and INM in SNEs can benefit university students'well-being.INM in SNEs offers a promising alternative for those with limited access to natural settings,contributing meaningfully to stress reduction and overall well-being.This study highlights the potential for nature-based strategies for human health in urban centres,advocating for further investigation into the long-term impacts of SNEs and optimal sensory configurations for maximizing therapeutic effects in urban populations.展开更多
Efficient multiple unmanned aerial vehicles(UAVs)path planning is crucial for improving mission completion efficiency in UAV operations.However,during the actual flight of UAVs,the flight time between nodes is always ...Efficient multiple unmanned aerial vehicles(UAVs)path planning is crucial for improving mission completion efficiency in UAV operations.However,during the actual flight of UAVs,the flight time between nodes is always influenced by external factors,making the original path planning solution ineffective.In this paper,the multi-depot multi-UAV path planning problem with uncertain flight time is modeled as a robust optimization model with a budget uncertainty set.Then,the robust optimization model is transformed into a mixed integer linear programming model by the strong duality theorem,which makes the problem easy to solve.To effectively solve large-scale instances,a simulated annealing algorithm with a robust feasibility check(SA-RFC)is developed.The numerical experiment shows that the SA-RFC can find high-quality solutions within a few seconds.Moreover,the effect of the task location distribution,depot counts,and variations in robustness parameters on the robust optimization solution is analyzed by using Monte Carlo experiments.The results demonstrate that the proposed robust model can effectively reduce the risk of the UAV failing to return to the depot without significantly compromising the profit.展开更多
In addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively understood.In this article,we discuss the effects of mesoscale G...In addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively understood.In this article,we discuss the effects of mesoscale GWs on the Es layers determined by using a newly developed model,MISE-1D(one-dimensional Model of Ionospheric Sporadic E),with low numerical dissipation and high resolution.Driven by the wind fields resolved by the high-resolution version of the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension(WACCM-X),the MISE-1D simulation revealed that GWs significantly influence the evolution of the Es layer above 100 km but have a very limited effect at lower altitudes.The effects of GWs are diverse and complex,generally including the generation of fluctuating wavelike structures on the Es layer with frequencies similar to those of the GWs.The mesoscale GWs can also cause increases in the density of Es layers,or they can disperse or diffuse the Es layers and increase their thickness.In addition,the presence of GWs is a key factor in sustaining the Es layers in some cases.展开更多
Based on presumed active fault and corresponding model, this paper predicted the near-fault ground motion filed of a scenario earthquake （Mw=6 3/4 ） in an active fault by the explicit finite element method in combin...Based on presumed active fault and corresponding model, this paper predicted the near-fault ground motion filed of a scenario earthquake （Mw=6 3/4 ） in an active fault by the explicit finite element method in combination with the source time function with improved transmitting artificial boundary and with high-frequency vibration contained. The results indicate that the improved artificial boundary is stable in numerical computation and the predicted strong ground motion has a consistent characteristic with the observed motion.展开更多
BACKGROUND Simulated microgravity environment can lead to gastrointestinal motility disturbance.The pathogenesis of gastrointestinal motility disorders is closely related to the stem cell factor(SCF)/c-kit signaling p...BACKGROUND Simulated microgravity environment can lead to gastrointestinal motility disturbance.The pathogenesis of gastrointestinal motility disorders is closely related to the stem cell factor(SCF)/c-kit signaling pathway associated with intestinal flora and Cajal stromal cells.Moreover,intestinal flora can also affect the regulation of SCF/c-kit signaling pathway,thus affecting the expression of Cajal stromal cells.Cajal cells are the pacemakers of gastrointestinal motility.AIM To investigate the effects of Bifidobacterium lactis(B.lactis)BLa80 on the intestinal flora of rats in simulated microgravity and on the gastrointestinal motility-related SCF/c-kit pathway.METHODS The internationally recognized tail suspension animal model was used to simulate the microgravity environment,and 30 rats were randomly divided into control group,tail suspension group and drug administration tail suspension group with 10 rats in each group for a total of 28 days.The tail group was given B.lactis BLa80 by intragastric administration,and the other two groups were given water intragastric administration,the concentration of intragastric administration was 0.1 g/mL,and each rat was 1 mL/day.Hematoxylin&eosin staining was used to observe the histopathological changes in each segment of the intestine of each group,and the expression levels of SCF,c-kit,extracellular signal-regulated kinase(ERK)and p-ERK in the gastric antrum of each group were detected by Western blotting and PCR.The fecal flora and mucosal flora of rats in each group were detected by 16S rRNA.RESULTS Simulated microgravity resulted in severe exfoliation of villi of duodenum,jejunum and ileum in rats,marked damage,increased space between villi,loose arrangement,shortened columnar epithelium of colon,less folds,narrower mucosal thickness,reduced goblet cell number and crypts,and significant improvement after probiotic intervention.Simulated microgravity reduced the expressions of SCF and c-kit,and increased the expressions of ERK and P-ERK in the gastric antrum of rats.However,after probiotic intervention,the expressions of SCF and ckit were increased,while the expressions of ERK and P-ERK were decreased,with statistical significance(P<0.05).In addition,simulated microgravity can reduce the operational taxonomic unit(OTU)of the overall intestinal flora of rats,B.lactis BLa80 can increase the OTU of rats,simulated microgravity can reduce the overall richness and diversity of stool flora of rats,increase the abundance of firmicutes in stool flora of rats,and reduce the abundance of Bacteroides in stool flora of rats,most of which are mainly beneficial bacteria.Simulated microgravity can increase the overall richness and diversity of mucosal flora,increase the abundance of Bacteroides and Desulphurides in the rat mucosal flora,and decrease the abundance of firmicutes,most of which are proteobacteria.After probiotics intervention,the overall Bacteroidetes trend in simulated microgravity rats was increased.CONCLUSION B.lactis BLa80 can ameliorate intestinal mucosal injury,regulate intestinal flora,inhibit ERK expression,and activate the SCF/c-kit signaling pathway,which may have a facilitating effect on gastrointestinal motility in simulated microgravity rats.展开更多
A microgravity environment has been shown to cause ocular damage and affect visual acuity,but the underlying mechanisms remain unclear.Therefore,we established an animal model of weightlessness via tail suspension to ...A microgravity environment has been shown to cause ocular damage and affect visual acuity,but the underlying mechanisms remain unclear.Therefore,we established an animal model of weightlessness via tail suspension to examine the pathological changes and molecular mechanisms of retinal damage under microgravity.After 4 weeks of tail suspension,there were no notable alterations in retinal function and morphology,while after 8 weeks of tail suspension,significant reductions in retinal function were observed,and the outer nuclear layer was thinner,with abundant apoptotic cells.To investigate the mechanism underlying the degenerative changes that occurred in the outer nuclear layer of the retina,proteomics was used to analyze differentially expressed proteins in rat retinas after 8 weeks of tail suspension.The results showed that the expression levels of fibroblast growth factor 2(also known as basic fibroblast growth factor)and glial fibrillary acidic protein,which are closely related to Müller cell activation,were significantly upregulated.In addition,Müller cell regeneration and Müller cell gliosis were observed after 4 and 8 weeks,respectively,of simulated weightlessness.These findings indicate that Müller cells play an important regulatory role in retinal outer nuclear layer degeneration during weightlessness.展开更多
In this manuscript we present a nonlinear site amplification model for ground-motion prediction equations(GMPEs)in Japan,using a site period-based site class and a site impedance ratio as site parameters.We used a lar...In this manuscript we present a nonlinear site amplification model for ground-motion prediction equations(GMPEs)in Japan,using a site period-based site class and a site impedance ratio as site parameters.We used a large number of shear-wave velocity profiles from the Kiban-Kyoshin network(KiK-net)and the Kyoshin network(K-NET)to construct the one-dimensional(1D)numerical models.The strong-motion records from rock-sites in Japan with different earthquake categories and taken from the Pacific Earthquake Engineering Research Center dataset were used in this study.We fit a set of 1D site amplification models using the spectral amplification ratios derived from 1D equivalent linear analyses.Parameters of site impedance ratios for both linear and nonlinear site response were included in the 1D model.The 1D model could be implemented into GMPEs using a new proposed adjustment method.The adjusted site amplification ratios retain the nonlinear characteristics of the 1D model for strong motions and match the linear amplification ratio in GMPE for weak motions.The nonlinearity of the present site model is reasonably similar to that of the historical models,and the present site model could satisfactorily capture the nonlinear site response in empirical data.展开更多
The stochastic finite-fault simulation method was applied to synthesize the horizontal ground acceleration seismograms produced by the MW6.1 Ludian earthquake on August 3,2014.For this purpose,we produced first a tota...The stochastic finite-fault simulation method was applied to synthesize the horizontal ground acceleration seismograms produced by the MW6.1 Ludian earthquake on August 3,2014.For this purpose,we produced first a total of 200 kinematic source models for the Ludian event,which are characterized by the heterogeneous slip on the conjugated ruptured fault and the slip-dependent spreading of the rupture front.The results indicated that the heterogeneous slip and the spatial extent of the ruptured fault play dominant roles in the spatial distribution of ground motions in the near-fault area.The peak ground accelerations(PGAs)and 5%-damped pseudospectral accelerations(PSAs)at periods shorter than 0.5 s estimated on the resulting synthetics generally match well with the observations at stations with Joyner-Boore distances(RJB)greater than 20 km.The synthetic PGVs and PSAs at periods of 0.5 s and 0.75 s are in good agreement with predicted medians by the Yu14 model(Yu et al.,2014).However,the synthetic results are generally much lower than the predicted medians by BSSA14 model(Boore et al.,2014).Moreover,the ground motion variability caused by the randomness in the source rupture process was evaluated by these synthetics.The standard deviations of PSAs on the base-10 logarithmic scale,Sigma[log10(PSA)],are closely dependent on either the spectral period or the RJB.The Sigma[log10(PSA)]remains a constant approximately 0.55 at periods shorter than 0.1 s,and then increase continuously up to^0.13 as the period increases from 0.1 to 2.0 s.The Sigma[log10(PSA)]values at periods of 0.1‒2.0 s show the downward tendency as the RJB values increase.However,the Sigma[log10(PSA)]values at periods shorter than 0.1 s decrease as the RJB values increase up to^50 km,and then increase with the increasing RJB.Furthermore,we found that the ground-motion variability shows the significant dependence on the azimuth.展开更多
In this study,naringin was encapsulated in microspheres and its simulated digestive behavior in vitro was examined.Then naringin microspheres was added in yogurt to investigate the rheology and antioxidant activities....In this study,naringin was encapsulated in microspheres and its simulated digestive behavior in vitro was examined.Then naringin microspheres was added in yogurt to investigate the rheology and antioxidant activities.The results indicated that encapsulating naringin in microspheres delayed its digestion in the stomach,allowing more release in the intestinal part.All kinds of yogurt were solid-like in nature and the addition of microspheres increased the elastic modulus and viscosity.The naringin and microspheres incorporation enhanced the total phenolic content of the yogurt to 6.7 and 8.8 mg of gallic acid equivalent/mL,respectively.All kinds of yogurt demonstrated more than 80%scavenging ability for hydroxyl radicals at 20μL whey/mL.The addition of microspheres improved the DPPH radical scavenging ability of yogurt.This study provides a new idea for the application of polyphenols in food and the development of functional yogurt.展开更多
The air-sea interactions with the submesoscale warm filament of the oceanic mixed layer are simulated by a coupled atmosphere-ocean model of the parallelized lager eddy simulation model.The results show that the warm ...The air-sea interactions with the submesoscale warm filament of the oceanic mixed layer are simulated by a coupled atmosphere-ocean model of the parallelized lager eddy simulation model.The results show that the warm core of the oceanic warm filament heats the bottom air of the atmospheric boundary layer,the rise of the bottom warm air results in the formation of the atmospheric warm filament.The variation in the width of the oceanic warm filament is generated by the change in the direction of the secondary circulations.The variation in the width of the atmospheric warm filament is created by that of the oceanic warm filament,because the direction of the secondary circulations of the atmospheric warm filament is invariable with time.The Coriolis effect results in the change in the direction of the secondary circulations for the oceanic warm filament.The secondary circulations of the atmospheric warm filament are produced by the rise of the bottom warm air caused by the oceanic warm filament,which leads to the unchanged direction of the secondary circulations.The thermal convection turbulence caused by the temperature difference of the ocean and atmosphere gradually weakens the structure of the oceanic and atmospheric warm filaments.展开更多
The prebiotic effects of hyaluronan(HA)are widely recognized,contributing to improved gut health and immune modulation.Despite its extensive use as dietary supplement,the specific interactions between HA oligosacchari...The prebiotic effects of hyaluronan(HA)are widely recognized,contributing to improved gut health and immune modulation.Despite its extensive use as dietary supplement,the specific interactions between HA oligosaccharides(o-HAs)and the gut microbiome remain largely unexplored.To investigate its role and metabolic fate in gut homeostasis,200 mg/day of o-HAs(average molecule weight 1 kDa)were added to an automated computer-controlled SIMulator of the Gastrointestinal tract(SIMGI).The results revealed a significant reshaping of the intestinal flora composition by o-HAs,notably reducing the Firmicutes/Bacteroides ratio.Fermentation of o-HAs by gut microbiota significantly increased the abundance of Bifidobacterium,Prevotellaceae_Prevotella,Dialister,Eubacterium,and Sutterella,but decreased that of Catenibacterium,Oscillospira,Klebsiella,and Citrobacter(P<0.05).This corresponded with significant enhancements in the content of short-chain fatty acids(SCFAs)such as acetic acid,propionic acid and n-butyric acid,highlighting the significant impact of o-HAs at the genus level.Furthermore,analysis of microbial function predicted the downregulation of pathological events in nine human diseases,particularly infectious ones(parasitic and bacterial).Potential inhibitions were observed in metabolic pathways associated with pentose and glucuronate interconversions as well as cationic antimicrobial peptide resistance.These findings underscore the in vitro prebiotic effects of o-HAs and their potential relevance in managing diverticular diseases or preventing metabolic disorders through the regulation of gut microbiota.展开更多
Ingestion of microplastics by various organisms has been widely evidenced.Chemicals associated with microplastics(MPs)may be released to digestive tracts upon ingestion.However,the effect of aging and temperature on t...Ingestion of microplastics by various organisms has been widely evidenced.Chemicals associated with microplastics(MPs)may be released to digestive tracts upon ingestion.However,the effect of aging and temperature on the chemical desorption for MPs remains poorly understood.The exposure of polyethylene(PE)particles to UV radiation in dry air,tap water,and sea water was conducted to mimic the aging process of MPs in different environments.Polychlorinated biphenyls(PCBs),as a typical hydrophobic organic contaminant,were preloaded in these aged and pristine PE.The desorption was performed by exposing preloaded PE particles in simulated gastric and gut fluids at 25℃and 40℃.After UV aging,the average diameter of PE particles decreased rapidly with aging time,indicating continuously fragmentation of PE under UV exposure.The desorption of PCBs from PE particles under different conditions varied from 7%to 40%,and that from aged PE in gut fluid at 37℃was significantly higher than those under other conditions(P<0.05).Furthermore,a clear declining trend was observed as lg K_(ow)(octanol-water partition coefficient)value increased.The aging process,hydrophobicity of chemicals,and incubation temperature were important factors on the desorption of PCBs from PE.The present study helps understand the desorption of PCBs from microplastics and the potential risks of microplastics ingestion by organisms.展开更多
The high melting point element W and the rare earth element Ce were added to 18Cr-Mo(444-type)ferritic stainless steel to improve its high-temperature oxidation resistance in exhaust gas.A simulated exhaust gas was fi...The high melting point element W and the rare earth element Ce were added to 18Cr-Mo(444-type)ferritic stainless steel to improve its high-temperature oxidation resistance in exhaust gas.A simulated exhaust gas was filled in the simultaneous thermal analyzer to simulate the service environment,and the oxidation behavior in high-temperature exhaust gas environment of 444-type ferritic stainless steel alloyed with W and Ce was investigated.The oxide structure and composition formed in this process were analyzed and characterized by scanning electron microscopy/energy-dispersive spectroscopy and electron probe analysis,and the mechanism of W and Ce in the oxidation process was revealed.The results show that 18Cr-Mo ferritic stainless steel containing W and Ce has better oxidation resistance in high-temperature exhaust gas.The element W can promote the precipitation of Laves phase at the matrix/interface,inhibit the interface diffusion of oxidizing elements and prevent the inward growth of the oxide film.The element Ce can suppress the volume of SiO_(2)at the oxide film/interface,reducing the breakaway oxidation caused by cracking of the oxide film.The CeO_(2)provides nucleation sites for oxide particles,promoting the healing of cracks and voids within the oxide film.展开更多
Agile earth observation satellites(AEOSs)represent a new generation of satellites with three degrees of freedom(pitch,roll,and yaw);they possess a long visible time window(VTW)for ground targets and support imaging at...Agile earth observation satellites(AEOSs)represent a new generation of satellites with three degrees of freedom(pitch,roll,and yaw);they possess a long visible time window(VTW)for ground targets and support imaging at any moment within the VTW.However,different observation times demonstrate different cloud cover distributions,which exhibit different effects on the AEOS observation.Previous studies ignored pitch angles,discretized VTWs,or fixed cloud cover for every VTW,which led to the loss of intermediate observation states,thus these studies are not suitable for AEOS scheduling considering cloud cover distribution.In this study,a relationship formula between the cloud cover and observation time is proposed to calculate the cloud cover for every observation time,and a relationship formula between the observation time and pitch angle is designed to calculate the pitch angle for every observation time in the VTW.A refined model including the pitch angle,roll angle,and cloud cover distribution is established,which can make the scheme closer to the actual application of AEOSs.A hybrid genetic simulated annealing(HGSA)algorithm for AEOS scheduling is proposed,which integrates the advantages of genetic and simulated annealing algorithms and can effectively avoid falling into a local optimal solution.The experiments are conducted to compare the proposed algorithm with the traditional algorithms,the results verify that the proposed model and algorithm are efficient and effective for AEOS scheduling considering cloud cover distribution.展开更多
Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing addit...Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.展开更多
Inferring phylogenetic trees from molecular sequences is a cornerstone of evolutionary biology.Many standard phylogenetic methods(such as maximum-likelihood[ML])rely on explicit models of sequence evolution and thus o...Inferring phylogenetic trees from molecular sequences is a cornerstone of evolutionary biology.Many standard phylogenetic methods(such as maximum-likelihood[ML])rely on explicit models of sequence evolution and thus often suffer from model misspecification or inadequacy.The on-rising deep learning(DL)techniques offer a powerful alternative.Deep learning employs multi-layered artificial neural networks to progressively transform input data into more abstract and complex representations.DL methods can autonomously uncover meaningful patterns from data,thereby bypassing potential biases introduced by predefined features(Franklin,2005;Murphy,2012).Recent efforts have aimed to apply deep neural networks(DNNs)to phylogenetics,with a growing number of applications in tree reconstruction(Suvorov et al.,2020;Zou et al.,2020;Nesterenko et al.,2022;Smith and Hahn,2023;Wang et al.,2023),substitution model selection(Abadi et al.,2020;Burgstaller-Muehlbacher et al.,2023),and diversification rate inference(Voznica et al.,2022;Lajaaiti et al.,2023;Lambert et al.,2023).In phylogenetic tree reconstruction,PhyDL(Zou et al.,2020)and Tree_learning(Suvorov et al.,2020)are two notable DNN-based programs designed to infer unrooted quartet trees directly from alignments of four amino acid(AA)and DNA sequences,respectively.展开更多
基金funded by UBC Forest and Human Wellbeing Research(Grant No.GR020223)。
文摘The rise in urbanization has increasingly restricted access to natural environments,posing substantial risks to the physical and mental health of urban populations,including university students and other high-stress groups.This study examines the comparative effects of outdoor forest meditation(OFM)and indoor nature meditation(INM)in simulated nature environments(SNEs)on the physiological and psychological health of university students.A pretestposttest repeated measures design was employed,with 40students participating in three replicated OFM sessions and three identical INM sessions across varied SNE settings.Key physiological metrics,including heart rate(HR),blood pressure(BP),and salivary amylase concentration(SAC),were measured before and after each session.Psychological well-being was assessed using the Perceived Stress Scale-10(PSS-10)and Profile of Mood States(POMS).Results revealed significant reductions(p<0.05)in most post-intervention outcomes,except in the second indoor session across physiologic al and psychologic al responses,while multi-sensory INM sessions produced comparable benefits.Notably,SNEs with enhanced sensory components were effective,though slightly less impactful than OFM.These findings suggest that both OFM in nature and INM in SNEs can benefit university students'well-being.INM in SNEs offers a promising alternative for those with limited access to natural settings,contributing meaningfully to stress reduction and overall well-being.This study highlights the potential for nature-based strategies for human health in urban centres,advocating for further investigation into the long-term impacts of SNEs and optimal sensory configurations for maximizing therapeutic effects in urban populations.
基金supported by the National Natural Science Foundation of China(72571094,72271076,71871079)。
文摘Efficient multiple unmanned aerial vehicles(UAVs)path planning is crucial for improving mission completion efficiency in UAV operations.However,during the actual flight of UAVs,the flight time between nodes is always influenced by external factors,making the original path planning solution ineffective.In this paper,the multi-depot multi-UAV path planning problem with uncertain flight time is modeled as a robust optimization model with a budget uncertainty set.Then,the robust optimization model is transformed into a mixed integer linear programming model by the strong duality theorem,which makes the problem easy to solve.To effectively solve large-scale instances,a simulated annealing algorithm with a robust feasibility check(SA-RFC)is developed.The numerical experiment shows that the SA-RFC can find high-quality solutions within a few seconds.Moreover,the effect of the task location distribution,depot counts,and variations in robustness parameters on the robust optimization solution is analyzed by using Monte Carlo experiments.The results demonstrate that the proposed robust model can effectively reduce the risk of the UAV failing to return to the depot without significantly compromising the profit.
基金supported by the Project of Stable Support for Youth Teams in Basic Research Field,Chinese Academy of Sciences(CASGrant No.YSBR-018)+2 种基金the B-type Strategic Priority Program of CAS(Grant No.XDB41000000)the National Natural Science Foundation of China(Grant No.42204165)the National Key Research and Development Program(Grant No.2022YFF0504400).
文摘In addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively understood.In this article,we discuss the effects of mesoscale GWs on the Es layers determined by using a newly developed model,MISE-1D(one-dimensional Model of Ionospheric Sporadic E),with low numerical dissipation and high resolution.Driven by the wind fields resolved by the high-resolution version of the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension(WACCM-X),the MISE-1D simulation revealed that GWs significantly influence the evolution of the Es layer above 100 km but have a very limited effect at lower altitudes.The effects of GWs are diverse and complex,generally including the generation of fluctuating wavelike structures on the Es layer with frequencies similar to those of the GWs.The mesoscale GWs can also cause increases in the density of Es layers,or they can disperse or diffuse the Es layers and increase their thickness.In addition,the presence of GWs is a key factor in sustaining the Es layers in some cases.
基金Heilongjiang Province Postdoctoral Science Foundation and China Earthquake Administration’s Tenth Five-year Plan Project
文摘Based on presumed active fault and corresponding model, this paper predicted the near-fault ground motion filed of a scenario earthquake （Mw=6 3/4 ） in an active fault by the explicit finite element method in combination with the source time function with improved transmitting artificial boundary and with high-frequency vibration contained. The results indicate that the improved artificial boundary is stable in numerical computation and the predicted strong ground motion has a consistent characteristic with the observed motion.
文摘BACKGROUND Simulated microgravity environment can lead to gastrointestinal motility disturbance.The pathogenesis of gastrointestinal motility disorders is closely related to the stem cell factor(SCF)/c-kit signaling pathway associated with intestinal flora and Cajal stromal cells.Moreover,intestinal flora can also affect the regulation of SCF/c-kit signaling pathway,thus affecting the expression of Cajal stromal cells.Cajal cells are the pacemakers of gastrointestinal motility.AIM To investigate the effects of Bifidobacterium lactis(B.lactis)BLa80 on the intestinal flora of rats in simulated microgravity and on the gastrointestinal motility-related SCF/c-kit pathway.METHODS The internationally recognized tail suspension animal model was used to simulate the microgravity environment,and 30 rats were randomly divided into control group,tail suspension group and drug administration tail suspension group with 10 rats in each group for a total of 28 days.The tail group was given B.lactis BLa80 by intragastric administration,and the other two groups were given water intragastric administration,the concentration of intragastric administration was 0.1 g/mL,and each rat was 1 mL/day.Hematoxylin&eosin staining was used to observe the histopathological changes in each segment of the intestine of each group,and the expression levels of SCF,c-kit,extracellular signal-regulated kinase(ERK)and p-ERK in the gastric antrum of each group were detected by Western blotting and PCR.The fecal flora and mucosal flora of rats in each group were detected by 16S rRNA.RESULTS Simulated microgravity resulted in severe exfoliation of villi of duodenum,jejunum and ileum in rats,marked damage,increased space between villi,loose arrangement,shortened columnar epithelium of colon,less folds,narrower mucosal thickness,reduced goblet cell number and crypts,and significant improvement after probiotic intervention.Simulated microgravity reduced the expressions of SCF and c-kit,and increased the expressions of ERK and P-ERK in the gastric antrum of rats.However,after probiotic intervention,the expressions of SCF and ckit were increased,while the expressions of ERK and P-ERK were decreased,with statistical significance(P<0.05).In addition,simulated microgravity can reduce the operational taxonomic unit(OTU)of the overall intestinal flora of rats,B.lactis BLa80 can increase the OTU of rats,simulated microgravity can reduce the overall richness and diversity of stool flora of rats,increase the abundance of firmicutes in stool flora of rats,and reduce the abundance of Bacteroides in stool flora of rats,most of which are mainly beneficial bacteria.Simulated microgravity can increase the overall richness and diversity of mucosal flora,increase the abundance of Bacteroides and Desulphurides in the rat mucosal flora,and decrease the abundance of firmicutes,most of which are proteobacteria.After probiotics intervention,the overall Bacteroidetes trend in simulated microgravity rats was increased.CONCLUSION B.lactis BLa80 can ameliorate intestinal mucosal injury,regulate intestinal flora,inhibit ERK expression,and activate the SCF/c-kit signaling pathway,which may have a facilitating effect on gastrointestinal motility in simulated microgravity rats.
基金supported by the Army Laboratory Animal Foundation of China,No.SYDW[2020]22(to TC)the Shaanxi Provincial Key R&D Plan General Project of China,No.2022SF-236(to YM)the National Natural Science Foundation of China,No.82202070(to TC)。
文摘A microgravity environment has been shown to cause ocular damage and affect visual acuity,but the underlying mechanisms remain unclear.Therefore,we established an animal model of weightlessness via tail suspension to examine the pathological changes and molecular mechanisms of retinal damage under microgravity.After 4 weeks of tail suspension,there were no notable alterations in retinal function and morphology,while after 8 weeks of tail suspension,significant reductions in retinal function were observed,and the outer nuclear layer was thinner,with abundant apoptotic cells.To investigate the mechanism underlying the degenerative changes that occurred in the outer nuclear layer of the retina,proteomics was used to analyze differentially expressed proteins in rat retinas after 8 weeks of tail suspension.The results showed that the expression levels of fibroblast growth factor 2(also known as basic fibroblast growth factor)and glial fibrillary acidic protein,which are closely related to Müller cell activation,were significantly upregulated.In addition,Müller cell regeneration and Müller cell gliosis were observed after 4 and 8 weeks,respectively,of simulated weightlessness.These findings indicate that Müller cells play an important regulatory role in retinal outer nuclear layer degeneration during weightlessness.
基金National Science Foundation of China under Grant No.51578470。
文摘In this manuscript we present a nonlinear site amplification model for ground-motion prediction equations(GMPEs)in Japan,using a site period-based site class and a site impedance ratio as site parameters.We used a large number of shear-wave velocity profiles from the Kiban-Kyoshin network(KiK-net)and the Kyoshin network(K-NET)to construct the one-dimensional(1D)numerical models.The strong-motion records from rock-sites in Japan with different earthquake categories and taken from the Pacific Earthquake Engineering Research Center dataset were used in this study.We fit a set of 1D site amplification models using the spectral amplification ratios derived from 1D equivalent linear analyses.Parameters of site impedance ratios for both linear and nonlinear site response were included in the 1D model.The 1D model could be implemented into GMPEs using a new proposed adjustment method.The adjusted site amplification ratios retain the nonlinear characteristics of the 1D model for strong motions and match the linear amplification ratio in GMPE for weak motions.The nonlinearity of the present site model is reasonably similar to that of the historical models,and the present site model could satisfactorily capture the nonlinear site response in empirical data.
基金supported by the Science Foundation of the Institute of Engineering Mechanics,China Earthquake Administration(No.2018B03)National Natural Science Foundation of China(No.51808514).
文摘The stochastic finite-fault simulation method was applied to synthesize the horizontal ground acceleration seismograms produced by the MW6.1 Ludian earthquake on August 3,2014.For this purpose,we produced first a total of 200 kinematic source models for the Ludian event,which are characterized by the heterogeneous slip on the conjugated ruptured fault and the slip-dependent spreading of the rupture front.The results indicated that the heterogeneous slip and the spatial extent of the ruptured fault play dominant roles in the spatial distribution of ground motions in the near-fault area.The peak ground accelerations(PGAs)and 5%-damped pseudospectral accelerations(PSAs)at periods shorter than 0.5 s estimated on the resulting synthetics generally match well with the observations at stations with Joyner-Boore distances(RJB)greater than 20 km.The synthetic PGVs and PSAs at periods of 0.5 s and 0.75 s are in good agreement with predicted medians by the Yu14 model(Yu et al.,2014).However,the synthetic results are generally much lower than the predicted medians by BSSA14 model(Boore et al.,2014).Moreover,the ground motion variability caused by the randomness in the source rupture process was evaluated by these synthetics.The standard deviations of PSAs on the base-10 logarithmic scale,Sigma[log10(PSA)],are closely dependent on either the spectral period or the RJB.The Sigma[log10(PSA)]remains a constant approximately 0.55 at periods shorter than 0.1 s,and then increase continuously up to^0.13 as the period increases from 0.1 to 2.0 s.The Sigma[log10(PSA)]values at periods of 0.1‒2.0 s show the downward tendency as the RJB values increase.However,the Sigma[log10(PSA)]values at periods shorter than 0.1 s decrease as the RJB values increase up to^50 km,and then increase with the increasing RJB.Furthermore,we found that the ground-motion variability shows the significant dependence on the azimuth.
基金funded by the People’s Livelihood Plan Project of Department of Science and Technology of Liaoning Province(2021JH2/10300069,2019-ZD-0845)the Department of Education of Liaoning Province(Natural Science,Strategic Industrialization Project,LJ212410163061)the Liaoning Province College Students Innovation and Entrepreneurship Training Program(S202410163077).
文摘In this study,naringin was encapsulated in microspheres and its simulated digestive behavior in vitro was examined.Then naringin microspheres was added in yogurt to investigate the rheology and antioxidant activities.The results indicated that encapsulating naringin in microspheres delayed its digestion in the stomach,allowing more release in the intestinal part.All kinds of yogurt were solid-like in nature and the addition of microspheres increased the elastic modulus and viscosity.The naringin and microspheres incorporation enhanced the total phenolic content of the yogurt to 6.7 and 8.8 mg of gallic acid equivalent/mL,respectively.All kinds of yogurt demonstrated more than 80%scavenging ability for hydroxyl radicals at 20μL whey/mL.The addition of microspheres improved the DPPH radical scavenging ability of yogurt.This study provides a new idea for the application of polyphenols in food and the development of functional yogurt.
基金The Scientific Research Fund for Doctor/Professor of Hezhou University under contract No.2024BSQD01the National Natural Science Foundation of China under contract No.42466001the project supported by Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)under contract No.SML2023SP240。
文摘The air-sea interactions with the submesoscale warm filament of the oceanic mixed layer are simulated by a coupled atmosphere-ocean model of the parallelized lager eddy simulation model.The results show that the warm core of the oceanic warm filament heats the bottom air of the atmospheric boundary layer,the rise of the bottom warm air results in the formation of the atmospheric warm filament.The variation in the width of the oceanic warm filament is generated by the change in the direction of the secondary circulations.The variation in the width of the atmospheric warm filament is created by that of the oceanic warm filament,because the direction of the secondary circulations of the atmospheric warm filament is invariable with time.The Coriolis effect results in the change in the direction of the secondary circulations for the oceanic warm filament.The secondary circulations of the atmospheric warm filament are produced by the rise of the bottom warm air caused by the oceanic warm filament,which leads to the unchanged direction of the secondary circulations.The thermal convection turbulence caused by the temperature difference of the ocean and atmosphere gradually weakens the structure of the oceanic and atmospheric warm filaments.
基金financially supported by the National Natural Science Foundation of China(32000058)the Fundamental Research Funds for the Central Universities(JUSRP622003)。
文摘The prebiotic effects of hyaluronan(HA)are widely recognized,contributing to improved gut health and immune modulation.Despite its extensive use as dietary supplement,the specific interactions between HA oligosaccharides(o-HAs)and the gut microbiome remain largely unexplored.To investigate its role and metabolic fate in gut homeostasis,200 mg/day of o-HAs(average molecule weight 1 kDa)were added to an automated computer-controlled SIMulator of the Gastrointestinal tract(SIMGI).The results revealed a significant reshaping of the intestinal flora composition by o-HAs,notably reducing the Firmicutes/Bacteroides ratio.Fermentation of o-HAs by gut microbiota significantly increased the abundance of Bifidobacterium,Prevotellaceae_Prevotella,Dialister,Eubacterium,and Sutterella,but decreased that of Catenibacterium,Oscillospira,Klebsiella,and Citrobacter(P<0.05).This corresponded with significant enhancements in the content of short-chain fatty acids(SCFAs)such as acetic acid,propionic acid and n-butyric acid,highlighting the significant impact of o-HAs at the genus level.Furthermore,analysis of microbial function predicted the downregulation of pathological events in nine human diseases,particularly infectious ones(parasitic and bacterial).Potential inhibitions were observed in metabolic pathways associated with pentose and glucuronate interconversions as well as cationic antimicrobial peptide resistance.These findings underscore the in vitro prebiotic effects of o-HAs and their potential relevance in managing diverticular diseases or preventing metabolic disorders through the regulation of gut microbiota.
基金Supported by the National Natural Science Foundation of China(No.21936004)the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(No.SML2021SP208)the Fundamental Research Funds for the Central Universities(No.21623118)。
文摘Ingestion of microplastics by various organisms has been widely evidenced.Chemicals associated with microplastics(MPs)may be released to digestive tracts upon ingestion.However,the effect of aging and temperature on the chemical desorption for MPs remains poorly understood.The exposure of polyethylene(PE)particles to UV radiation in dry air,tap water,and sea water was conducted to mimic the aging process of MPs in different environments.Polychlorinated biphenyls(PCBs),as a typical hydrophobic organic contaminant,were preloaded in these aged and pristine PE.The desorption was performed by exposing preloaded PE particles in simulated gastric and gut fluids at 25℃and 40℃.After UV aging,the average diameter of PE particles decreased rapidly with aging time,indicating continuously fragmentation of PE under UV exposure.The desorption of PCBs from PE particles under different conditions varied from 7%to 40%,and that from aged PE in gut fluid at 37℃was significantly higher than those under other conditions(P<0.05).Furthermore,a clear declining trend was observed as lg K_(ow)(octanol-water partition coefficient)value increased.The aging process,hydrophobicity of chemicals,and incubation temperature were important factors on the desorption of PCBs from PE.The present study helps understand the desorption of PCBs from microplastics and the potential risks of microplastics ingestion by organisms.
基金the joint financial support from the National Natural Science Foundation of China and Baowu Group Co.,Ltd.(Grant No.U1660205)the Fundamental Research Funds for the Central Universities(Grant No.N2007001).
文摘The high melting point element W and the rare earth element Ce were added to 18Cr-Mo(444-type)ferritic stainless steel to improve its high-temperature oxidation resistance in exhaust gas.A simulated exhaust gas was filled in the simultaneous thermal analyzer to simulate the service environment,and the oxidation behavior in high-temperature exhaust gas environment of 444-type ferritic stainless steel alloyed with W and Ce was investigated.The oxide structure and composition formed in this process were analyzed and characterized by scanning electron microscopy/energy-dispersive spectroscopy and electron probe analysis,and the mechanism of W and Ce in the oxidation process was revealed.The results show that 18Cr-Mo ferritic stainless steel containing W and Ce has better oxidation resistance in high-temperature exhaust gas.The element W can promote the precipitation of Laves phase at the matrix/interface,inhibit the interface diffusion of oxidizing elements and prevent the inward growth of the oxide film.The element Ce can suppress the volume of SiO_(2)at the oxide film/interface,reducing the breakaway oxidation caused by cracking of the oxide film.The CeO_(2)provides nucleation sites for oxide particles,promoting the healing of cracks and voids within the oxide film.
基金supported by the National Natural Science Foundation of China(72071064,72271074,72001004)the Anhui Provincial Natural Science Foundation(2408085QG221).
文摘Agile earth observation satellites(AEOSs)represent a new generation of satellites with three degrees of freedom(pitch,roll,and yaw);they possess a long visible time window(VTW)for ground targets and support imaging at any moment within the VTW.However,different observation times demonstrate different cloud cover distributions,which exhibit different effects on the AEOS observation.Previous studies ignored pitch angles,discretized VTWs,or fixed cloud cover for every VTW,which led to the loss of intermediate observation states,thus these studies are not suitable for AEOS scheduling considering cloud cover distribution.In this study,a relationship formula between the cloud cover and observation time is proposed to calculate the cloud cover for every observation time,and a relationship formula between the observation time and pitch angle is designed to calculate the pitch angle for every observation time in the VTW.A refined model including the pitch angle,roll angle,and cloud cover distribution is established,which can make the scheme closer to the actual application of AEOSs.A hybrid genetic simulated annealing(HGSA)algorithm for AEOS scheduling is proposed,which integrates the advantages of genetic and simulated annealing algorithms and can effectively avoid falling into a local optimal solution.The experiments are conducted to compare the proposed algorithm with the traditional algorithms,the results verify that the proposed model and algorithm are efficient and effective for AEOS scheduling considering cloud cover distribution.
基金National Key Research and Development Program of China(2022YFB4600902)Shandong Provincial Science Foundation for Outstanding Young Scholars(ZR2024YQ020)。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.
基金supported by the National Key R&D Program of China(2022YFD1401600)the National Science Foundation for Distinguished Young Scholars of Zhejang Province,China(LR23C140001)supported by the Key Area Research and Development Program of Guangdong Province,China(2018B020205003 and 2020B0202090001).
文摘Inferring phylogenetic trees from molecular sequences is a cornerstone of evolutionary biology.Many standard phylogenetic methods(such as maximum-likelihood[ML])rely on explicit models of sequence evolution and thus often suffer from model misspecification or inadequacy.The on-rising deep learning(DL)techniques offer a powerful alternative.Deep learning employs multi-layered artificial neural networks to progressively transform input data into more abstract and complex representations.DL methods can autonomously uncover meaningful patterns from data,thereby bypassing potential biases introduced by predefined features(Franklin,2005;Murphy,2012).Recent efforts have aimed to apply deep neural networks(DNNs)to phylogenetics,with a growing number of applications in tree reconstruction(Suvorov et al.,2020;Zou et al.,2020;Nesterenko et al.,2022;Smith and Hahn,2023;Wang et al.,2023),substitution model selection(Abadi et al.,2020;Burgstaller-Muehlbacher et al.,2023),and diversification rate inference(Voznica et al.,2022;Lajaaiti et al.,2023;Lambert et al.,2023).In phylogenetic tree reconstruction,PhyDL(Zou et al.,2020)and Tree_learning(Suvorov et al.,2020)are two notable DNN-based programs designed to infer unrooted quartet trees directly from alignments of four amino acid(AA)and DNA sequences,respectively.
