Low-visibility phenomena strongly impact the environment,as well as transportation,aviation and other fields that are closely related to people's livelihoods;thus,they represent important ecological issues of soci...Low-visibility phenomena strongly impact the environment,as well as transportation,aviation and other fields that are closely related to people's livelihoods;thus,they represent important ecological issues of social concern.Based on observation data concerning low-visibility phenomena derived from 105 national meteorological stations in Xinjiang,China over the past 20 years,we systematically analyzed the differences between manual and instrument observations for six types of low-visibility phenomena,with a focus on exploring their spatiotemporal distribution characteristics using instrument data.The results revealed that low-visibility phenomena were dominated by fog-and haze-related events(mist,fog,and haze)in northern Xinjiang and dust-related events(dust storms,blowing sand,and floating dust)in southern Xinjiang,with transitional characteristics observed in eastern Xinjiang.Compared with manual observations,the instrument measurements significantly improved the fine-scale low-visibility phenomenon identification process.On the basis of the instrument observation data,spatial-dimension analysis results indicated that low-visibility phenomena in Xinjiang were significantly influenced by terrain factors.Constrained by the Tianshan Mountains,haze-like phenomena formed a core agglomeration area in northern Xinjiang,whereas dust-and sand-related phenomena radiated outward,with the Taklimakan Desert at the center.Moreover,the gripping effect of the terrain promoted dust transmission along low-altitude channels.Temporally,fog-and haze-related phenomena occurred mainly during autumn and winter,and the proportion of these events decreased from 76.7%to 55.1%.The fog-and haze-related phenomena demonstrated a U-shaped rebound trend,while the proportion of mist phenomena decreased by 34.2%.Dust storms occurred during spring,accounting for 23.3%to 44.9%of all storms.Instrument measurement technology has the advantages of high spatial and temporal resolutions and multiparameter coordination but provides a limited dust-haze mixed-pollution identification capacity.This study provides crucial reference data for enhancing the understanding of low-visibility events in Xinjiang and the potential responses while improving the accuracy of pollution source tracking and meteorological process diagnosis tasks.展开更多
Coking industry is a potential source of heavy metals(HMs)pollution.However,its impacts to the groundwater of surrounding residential areas have not been well understood.This study investigated the pollution character...Coking industry is a potential source of heavy metals(HMs)pollution.However,its impacts to the groundwater of surrounding residential areas have not been well understood.This study investigated the pollution characteristics and health risks of HMs in groundwater nearby a typical coking plant.Nine HMs including Fe,Zn,Mo,As,Cu,Ni,Cr,Pb and Cd were analyzed.The average concentration of total HMswas higher in the nearby area(244.27μg/L)than that of remote area away the coking plant(89.15μg/L).The spatial distribution of pollution indices including heavy metal pollution index(HPI),Nemerow index(NI)and contamination degree(CD),all demonstrated higher values at the nearby residential areas,suggesting coking activity could significantly impact the HMs distribution characteristics.Four sources of HMs were identified by Positive Matrix Factorization(PMF)model,which indicated coal washing and coking emission were the dominant sources,accounted for 40.4%,and 31.0%,respectively.Oral ingestionwas found to be the dominant exposure pathway with higher exposure dose to children than adults.Hazard quotient(HQ)values were below 1.0,suggesting negligible non-carcinogenic health risks,while potential carcinogenic risks were from Pb and Ni with cancer risk(CR)values>10−6.Monte Carlo simulation matched well with the calculated results with HMs concentrations to be the most sensitive parameters.This study provides insights into understanding how the industrial coking activities can impact the HMs pollution characteristics in groundwater,thus facilitating the implement of HMs regulation in coking industries.展开更多
Synthetic phenolic antioxidants(SPAs)are widely used in diverse industries due to their exceptional antioxidant characteristics.However,human exposure to SPAs may cause health problems.In this study,226 dust samples w...Synthetic phenolic antioxidants(SPAs)are widely used in diverse industries due to their exceptional antioxidant characteristics.However,human exposure to SPAs may cause health problems.In this study,226 dust samples were collected from 10 provinces in China,and six SPAs(three parent SPAs and their three transformation products)were analyzed.The concentrations of6SPAs(the sum of six target compounds)ranged from 15.4 to 3210 ng/g(geometric mean(GM):169 ng/g).The highest concentration of6SPAswas found in Sichuan Province(GM:349 ng/g),which was approximately 4 times higher than that in Hubei Province(81.6 ng/g)(p<0.05).The concentrations of butylated hydroxytoluene(BHT),2,2'-methylene bis(4-methyl-6–tert-butylphenol)(AO2246),2,6-di–tert–butyl–1,4-benzoquinone(BHT-Q),2,6-di–tert–butyl–4-(hydroxymethyl)phenol(BHT-OH),and ∑_(p)-SPAs were substantially higher in dust from urban areas than rural areas(p<0.05).AO2246 concentration in dust from homes(GM:0.400 ng/g)was about 4 times higher than that in workplaces(0.116 ng/g)(p<0.01).Significantly higherp-SPAs concentrations were found in dust from homes(GM:17.5 ng/g)than workplaces(11.4 ng/g)(p<0.01).The estimated daily intakes(EDIs)of ∑_(6)SPAs exposed through dust ingestion were 0.582,0.342,0.197,0.076,and 0.080 ng/kg bw/day in different age groups,and exposed through dermal contact was 0.358,0.252,0.174,0.167,and 0.177 ng/kg bw/day.EDIs showed that the exposure risks of SPAs decreased with age.This is the first work to determine SPAs in dust from10 provinces in China and investigate the spatial distribution of SPAs in those regions.展开更多
Since scarce knowledge of soil mercury(Hg)concentrations and risks in the vulnerable Xinjiang,topsoils(0-15 cm)from its typical landscapes were extensively sampled.Topsoil total mercury(THg)concentrations varied broad...Since scarce knowledge of soil mercury(Hg)concentrations and risks in the vulnerable Xinjiang,topsoils(0-15 cm)from its typical landscapes were extensively sampled.Topsoil total mercury(THg)concentrations varied broadly between 0.9 and 35.3 ng/g,of which16.8%exceeded the background value of soil Hg for Xinjiang.Topsoil THg concentrations across various landscapes exhibited a declining order:farmland(11.7±6.0 ng/g)>grassland(10.5±8.5 ng/g)>woodland(10.2±8.2 ng/g)>desert(7.0±5.8 ng/g).The average topsoil THg concentration was higher in northwestern Xinjiang(11.3±7.2 ng/g)than that in southeastern Xinjiang(6.3±6.1 ng/g).Relatively high topsoil THg concentrations were observed near the cities with intensive human activities,followed by a gradual decline to the surroundings.The concentrations of topsoil THg were strongly correlated with the contents of total organic carbon(TOC),clay,silty,and sandy,and the distance from each sampling site to its nearest city,suggesting that the variation of topsoil Hg was significantly influenced by TOC content,soil granularity,and anthropogenic Hg emissions.Silty and TOC were the principal affecting factors,explaining 48.7%and 7.9%of the THg variation,respectively.The contamination and potential ecological risk evaluations revealed that topsoils in regions with dense populations were polluted with Hg and contained higher potential ecological risks.The health risk evaluations indicated that exposure risks of topsoil Hg were higher for children than those for adults.Fortunately,topsoil Hg posed acceptable risks to human health.展开更多
Poyang Lake,China's largest freshwater lake,is a critical wintering ground for most of the global Siberian Grane(Grus leucogeranus)population.However,increasingly prolonged dry seasons have degraded the natural we...Poyang Lake,China's largest freshwater lake,is a critical wintering ground for most of the global Siberian Grane(Grus leucogeranus)population.However,increasingly prolonged dry seasons have degraded the natural wetlands of Poyang Lake,forcing Siberian Cranes to shift to artificial habitats.From 2015 to 2023,field surveys revealed a substantial increase in the number of Siberian Cranes in artificial habitats,with peak counts reaching 3000individuals,accounting for up to 53%of the species'global population.Satellite telemetry of 13 individuals further confirmed the spatial use of these habitats,highlighting their consistent reliance on artificial sites over multiple years.Seven high-use hotspots were identified outside of Poyang Lake,including two artificial provisioning sites that supported dense foraging flocks for extended periods.Satellite telemetry confirmed this trend,with artificial habitats making up to 64.2%of the occurrence sites in some years.This reliance on artificial habitats was closely linked to the reduced tuber biomass in natural wetlands and low winter water levels in Poyang Lake,which collectively explained 83%of the variance in crane abundance in artificial habitats.Artificial habitat use peaked in December and January,indicating marked seasonal variation.Siberian Cranes also exhibited a pronounced circadian rhythm,foraging in artificial habitats during the day and returning to natural wetlands to roost at night.Despite the shift toward artificial habitats,natural wetlands remain critical for nighttime refuge.The continued dependence on artificial habitats raises concerns about disease transmission owing to dense congregations.Conservation strategies should prioritize both the careful management of artificial provisioning sites and the restoration of natural wetlands to improve food and habitat availability within natural ecosystems,ultimately enabling the return of Siberian Cranes to their traditional natural habitats.展开更多
The synergy of metal/oxygen vacancy(O_(v))pairs is critical in catalyzing activation of C-H,C=C,and C-O bonds.However,gaining fundamental understanding on spatial distance of metallic and O_(v)sites on catalyst surfac...The synergy of metal/oxygen vacancy(O_(v))pairs is critical in catalyzing activation of C-H,C=C,and C-O bonds.However,gaining fundamental understanding on spatial distance of metallic and O_(v)sites on catalyst surface would lead to unexpected chemoselectivity toward important and challenging reactions.In this work,we have proposed and validated unique Ni-O-Ce-O_(v)enriched Ni/CeO_(2)catalysts prepared by a deposition-precipitation method,for the transfer hydrogenation of lignin-derived guaiacol toward cyclohexanol rather than benzene derivatives.The counter-intuitively designed high Ni loading Ni_(2)0/CeO_(2)catalyst(20 wt%Ni content)displays a distance of 0.5 nm for Ni/O_(v)pairs with a remarkable activity(TOF:166.5 h^(-1))and 90%+selectivity for C_(Ar)=C_(Ar)bond saturation,outperforming better metal-dispersed Ni_(5)/CeO_(2)catalyst with limited presence of Ni-O-Ce-O_(v)sites.The high hydrogenation activity against hydrogenolysis reactions on Ni_(2)0/CeO_(2)catalyst is attributed to tunable Ni/O_(v)distances,which constrain the cleavage of CAr-OH bond and deep deoxygenation.Such spatial distribution effect has also facilitated tandem dehydrogenation(O-H bond cleavage)and hydrogenation(C_(Ar)=C_(Ar)hydrogenation)reactions,leading to cyclohexanol as the target product in the absence of externally added H_(2).Insights into spatial distribution of O_(v)sites open an alternative perspective in designing efficient catalysts toward producing value-added cyclic oxygenates through upgrading of lignin compounds.展开更多
This paper selects sampling sections for the mainstream and tributaries of the middle and lower reaches of the Yellow River,collects river water and sediment samples during the flood season for pollen analysis,and use...This paper selects sampling sections for the mainstream and tributaries of the middle and lower reaches of the Yellow River,collects river water and sediment samples during the flood season for pollen analysis,and uses methods such as Geodetector to explore the distribution characteristics and influencing factors of pollen.The results show significant variations in vegetation composition across different watersheds,leading to notable differences in both the percentage and concentration of pollen types.Pollen concentration in river water is generally higher in the mainstream compared to tributaries,while sediment pollen percentage and concentration are typically lower in the mainstream than in tributaries.The concentration of suspended solids is the most significant factor affecting pollen concentration in the Yellow River,with this effect being particularly prominent outside the Shanxi-Shaanxi Gorge.Abundant coarse sand and rapid flow velocities are likely responsible for the high suspended solids concentration and lower pollen concentration observed in the mainstream of the Shanxi-Shaanxi Gorge.In sediments,clay content is the primary factor influencing pollen concentration,and its interaction with silt and flow velocity has a more prominent influence on pollen concentration.At the Yellow River section below the Shanxi-Shaanxi Gorge,sediment pollen and clay concentrations significantly increase.The changes in pollen concentration in the river water before and after the reservoir are consistent with the suspended solids concentration,while the changes in sediment pollen concentration are consistent with the clay content.Notably,pollen concentrations in sediments decrease more significantly after passing through a reservoir compared to changes observed in river water samples.Overall,there is a strong correlation between river pollen and topsoil pollen,which can provide a reliable reflection of the broader vegetation landscape of the watershed.The findings can provide support for paleoenvironmental reconstruction using pollen from alluvial sediments or lakes with river inflows.展开更多
The space-air-ground integrated network(SAGIN)is an important sixth-generation(6G)scenario that is enabled by dynamic spot beam forming by a phased array antenna(PAA).The extremely high mobility of satellites and more...The space-air-ground integrated network(SAGIN)is an important sixth-generation(6G)scenario that is enabled by dynamic spot beam forming by a phased array antenna(PAA).The extremely high mobility of satellites and more complicated radio resource control(RRC)have brought introduced a new challenge,and the issue of determining appropriate moments and procedures for executing handover(HO)for all users in a coverage area is urgent.The existing research considers the users as an entirety,and it determines the HO moment under the assumption that all of the satellite subpoints(SSP)pass through the centre of the cell.However,when using this scheme,the HO failure ratio(HOFR)would experience great degradation caused by the imbalance between the unified HO moments and the uncertain spatial distribution of users’(SDU)spatial-temporal variation.This paper proposes a novel HO moment determination method for a low-orbit satellite internet network(LEO-SIN).The rules of SDU variance under SSP motion are first proposed,and they calculate dynamic UE requests within the constraints of the footprint boundary and with SSP motions.Then,we first formulate the problems of multiuser-directed graphs for HO moment determination and prove that it is a nondeterministic polynomial-time(NP)hard problem.An animal survival algorithm based on the Dingo of algorithm(DOA)is proposed to solve the above problems.Multiuser fused directed graphs are first designed to determine HO moments based on the rules of SDU variation and the animal survival algorithm.The simulations show that the proposed method has a better HO performance for LEO-SIN.展开更多
Based on the monitoring data of PM 10 concentration from six environmental monitoring stations and the ground meteorological observation data in Yantai City from 2019 to 2021,the spatial and temporal variation of PM 1...Based on the monitoring data of PM 10 concentration from six environmental monitoring stations and the ground meteorological observation data in Yantai City from 2019 to 2021,the spatial and temporal variation of PM 10 concentration and its relationship with meteorological factors were studied.The results show that from the perspective of temporal variation,the annual average of PM 10 concentration in Yantai City tended to decrease year by year.It was high in winter and spring and low in summer and autumn.In terms of monthly variation,the changing curve is U-shaped,and it was high in December and January but low in July and August.During a day,PM 10 concentration had two peaks.The first peak appeared approximately from 09:00 to 11:00,and the second peak can be found from 21:00 to 23:00.From the perspective of spatial distribution,PM 10 concentration was the highest in the development area and Fushan District.It was the highest in the west,followed by the east,while it was the lowest in the middle.The spatial difference rate was the highest in summer.Average temperature,relative humidity,wind speed and precipitation were the main meteorological factors influencing PM 10 concentration in Yantai area.PM 10 concentration was negatively correlated with average temperature and relative humidity,and the correlation was the most significant from June to October.It was negatively correlated with wind speed and precipitation,and the correlation was different in various months.The negative correlation was significant in summer and winter.展开更多
As a significant city in the Yangtze River Delta regions,Hefei has experienced rapid changes in the sources of air pollution due to its high-speed economic development and urban expansion.However,there has been limite...As a significant city in the Yangtze River Delta regions,Hefei has experienced rapid changes in the sources of air pollution due to its high-speed economic development and urban expansion.However,there has been limited research in recent years on the spatial-temporal distribution and emission of its atmospheric pollutants.To address this,this study conducted mobile observations of urban roads using the Mobile-DOAS instrument from June 2021 to May 2022.The monitoring results exhibit a favourable consistent with TROPOMI satellite data and ground monitoring station data.Temporally,there were pronounced seasonal variations in air pollutants.Spatially,high concentration of HCHO and NO_(2)were closely associated with traffic congestion on roadways,while heightened SO_(2)levels were attributed to winter heating and industrial emissions.The study also revealed that with the implementation of road policies,the average vehicle speed increased by 95.4%,while the NO concentration decreased by 54.4%.In the estimation of urban NO_(x)emission flux,it was observed that in temporal terms,compared with inventory data,the emissions calculated viamobile measurements exhibitedmore distinct seasonal patterns,with the highest emission rate of 349 g/sec in winter and the lowest of 142 g/sec in summer.In spatial terms,the significant difference in emissions between the inner and outer ring roads also suggests the presence of the city’s primary NO_(x)emission sources in the area between these two rings.This study offers data support for formulating the next phase of air pollution control measures in urban areas.展开更多
Antarctic krill(Euphausia superba),widely distributes around Antarctica,is a key species supporting the biodiversity of the Southern Ocean ecosystem.The Commission for the Conservation of Antarctic Marine Living Resou...Antarctic krill(Euphausia superba),widely distributes around Antarctica,is a key species supporting the biodiversity of the Southern Ocean ecosystem.The Commission for the Conservation of Antarctic Marine Living Resources(CCAMLR)has thus managed the krill fishery according to a precautionary way.Currently,CCAMLR is making effort to develop a refined krill fishery management approach based on more solid science,which requires accurate predictions of krill distribution.To address this need,this study investigated the effects of algorithm and spatial resolution on the performance of Antarctic krill distribution modelling.We integrated acoustic data from 4 surveys conducted in the waters adjacent to the Antarctic Peninsula with 11 environmental variables characterizing krill prey conditions,water mass properties,and seafloor topography.These data were processed at 4 spatial resolutions(5,10,15,and 20 km)to fit distribution models using 4 algorithms:Random Forests(RF),Generalized Additive Models(GAM),Extreme Gradient Boosting(XGBoost),and Artificial Neural Networks(ANN).Model performance was assessed and compared in terms of goodness-of-fit and predictive accuracy.The results showed that RF achieved the highest predictive performance at most resolutions,whereas GAM performed best at the coarsest resolution(20 km).XGBoost closely following RF in accuracy and demonstrated robustness as evidenced by the highly consistent partial dependence curves across resolutions.In contrast,ANN exhibited limitations with smaller sample sizes,resulting in comparatively poorer predictive performance.The analysis revealed a trade-off whereby reducing spatial resolution improved model fit and mitigated zero-inflation at the expense of fine-scale information and overall predictive accuracy.Ensemble models,integrating RF,GAM,and XGBoost,are proposed as potential balanced solutions to improve predictive stability,offering a more robust scientific basis for the refinement of krill management.展开更多
Medicinal plant diversity(MPD)is an indispensable part of global plant diversity,serving as the foundation for human survival by offering remedies and preventive measures against diseases.However,factors such as overe...Medicinal plant diversity(MPD)is an indispensable part of global plant diversity,serving as the foundation for human survival by offering remedies and preventive measures against diseases.However,factors such as overexploitation,competition from invasive alien species,and climate change,threaten the habitats of medicinal plants,necessitating a comprehensive understanding of their spatial distribution and suitable habitats.We leveraged a decade of field survey data on medicinal plant distribution in the Yinshan Mountains,combined with spatial analysis,species distribution modeling,and the Carnegie Ames Stanford Approach(CASA)to explore the MPD spatial distribution and suitable habitats.Spatial analysis revealed that the central and eastern parts of Yinshan Mountains were the primary MPD hotspots,with no cold spots evident at various spatial scales.As the spatial scale decreased,previous non-significant regions transformed into hotspots,with instances where large-scale hotspots became insignificant.These findings offer valuable guidance for safeguarding and nurturing MPD across diverse spatial scales.In future climate change scenarios within the shared socioeconomic pathways(SSP),the habitat suitability for MPD in the Yinshan Mountains predominantly remains concentrated in the central and eastern regions.Notably,areas with high net primary productivity(NPP)values and abundant vegetation coverage align closely with MPD habitat suitability areas,potentially contributing to the region's rich MPD.展开更多
Located in Nanhai Town,Songzi City,Hubei Province,Xiaonanhai Lake is the largest natural lake in Songzi.It was once severely polluted due to the discharge of urban and rural domestic sewage,disorderly development of a...Located in Nanhai Town,Songzi City,Hubei Province,Xiaonanhai Lake is the largest natural lake in Songzi.It was once severely polluted due to the discharge of urban and rural domestic sewage,disorderly development of agricultural planting,unregulated aquaculture,and poultry farming.However,relevant esti-mations of the pollutant content in its sediment have not been carried out.This study analyzed the spatial patterns of heavy metal pollution and eutrophication at 36 water sampling sites in the Xiaonanhai Lake area,focusing on eight heavy metals:Cd,Cr,Cu,Ni,As,Pb,Hg,and Zn.The nutrient status of the lake area was evaluated using the nitrogen-phosphorus comprehensive pollution index,and heavy metal pollution status of the lake area was evaluated using geo-accumulation and the potential ecological risk index.Spatial autocorrelation analysis revealed the spatial correlation and aggregation of eutrophication levels in Xiaonanhai Lake.The results showed that the overall trophic state of the Xiaonanhai Lake area was moderate eutrophication,with a gradually decreasing eutrophication level from north to south.The Chengnan Wastewater Treatment Plant in the northern part of the lake area and surface source pollution from aquaculture were the main nitrogen and phosphorus sources.The overall eco-logical risk index of heavy metal pollution was medium and gradually weakened from north to south,consistent with the thickness of the bottom mud.The heavy metal pollution load was mainly precipitated from the bottom mud in the lake area.The eutrophication and heavy metal pollution levels in the lake area showed significant positive spatial autocorrelation,the influence range of the regional eutrophication level was small,and the spatial heterogeneity of the eutrophication and heavy metal pollution levels in Xiaonanhai Lake was relatively high.The northern part of the lake was a hotspot(high/high aggregation)of eutrophication(p<0.01)while the southern part was a cold spot(low/low concentration;p<0.05).The middle and northern part of the lake area was the hot spot(high/high concentration)of heavy metal pollution level(p<0.1)while the southern part was the cold spot(low/low concentration;p<0.1).Therefore,when carrying out water environment management in Xiaonanhai Lake,the northern area and the middle area should be prioritized for eutrophication prevention and control and dredging.展开更多
Compared with Zn^(2+),the current mainly reported charge carrier for zinc hybrid capacitors,small-hydrated-sized and light-weight NH_(4)^(+)is expected as a better one to mediate cathodic interfacial electrochemical b...Compared with Zn^(2+),the current mainly reported charge carrier for zinc hybrid capacitors,small-hydrated-sized and light-weight NH_(4)^(+)is expected as a better one to mediate cathodic interfacial electrochemical behaviors,yet has not been unraveled.Here we propose an NH_(4)^(+)-modulated cationic solvation strategy to optimize cathodic spatial charge distribution and achieve dynamic Zn^(2+)/NH_(4)^(+)co-storage for boosting Zinc hybrid capacitors.Owing to the hierarchical cationic solvated structure in hybrid Zn(CF_(3)SO_(3))_(2)–NH_4CF_(3)SO_(3)electrolyte,high-reactive Zn^(2+)and small-hydrate-sized NH_4(H_(2)O))(4)^(+)induce cathodic interfacial Helmholtz plane reconfiguration,thus effectively enhancing the spatial charge density to activate 20%capacity enhancement.Furthermore,cathodic interfacial adsorbed hydrated NH_(4)^(+)ions afford high-kinetics and ultrastable C···H(NH_(4)^(+))charge storage process due to a much lower desolvation energy barrier compared with heavy and rigid Zn(H_(2)O)_6^(2+)(5.81 vs.14.90 eV).Consequently,physical uptake and multielectron redox of Zn^(2+)/NH_(4)^(+)in carbon cathode enable the zinc capacitor to deliver high capacity(240 mAh g^(-1)at 0.5 A g^(-1)),large-current tolerance(130 mAh g^(-1)at 50 A g^(-1))and ultralong lifespan(400,000cycles).This study gives new insights into the design of cathode–electrolyte interfaces toward advanced zinc-based energy storage.展开更多
To generate a neutron beam exhibiting a Maxwellian energy distribution with narrow emission angles for measuring the neutron capture reaction rates of the s-process nuclides,a monoenergetic 3.4 MeV proton beam produce...To generate a neutron beam exhibiting a Maxwellian energy distribution with narrow emission angles for measuring the neutron capture reaction rates of the s-process nuclides,a monoenergetic 3.4 MeV proton beam produced by the tandem-accelerator in the China Institute of Atomic Energy was utilized.The proton beam was first transmitted through a 60.5μm aluminum foil and then impinged on a natural LiF target to produce neutron beam via^(7)Li(p,n)7Be reaction.The quasi-Gaussian energy distribution of protons in the LiF target resulted in neutron energy spectra that agreed with a Maxwellian energy distribution at kT=(22±2)keV,which was achieved by integrating neutrons detected within an emission angle of 65.0°±2.6°using a ^(6)Li glass detector positioned at 65°relative to the proton beam direction.The narrow angular spread of the Maxwelliandistributed neutron beam enables direct measurement of neutron capture cross-sections for most s-process nuclides,overcoming previous experimental limitations associated with broad angular distributions.展开更多
Species distribution patterns is one of the important topics in ecology and biological conservation.Although species distribution models have been intensively used in the research,the effects of spatial associations a...Species distribution patterns is one of the important topics in ecology and biological conservation.Although species distribution models have been intensively used in the research,the effects of spatial associations and spatial dependence have been rarely taken into account in the modeling processes.Recently,Joint Species Distribution Models(JSDMs)offer the opportunity to consider both environmental factors and interspecific relationships as well as the role of spatial structures.This study uses the HMSC(Hierarchical Modelling of Species Communities)framework to model the multispecies distribution of a marine fish assemblage,in which spatial associations and spatial dependence is deliberately accounted for.Three HMSC models were implemented with different structures of random effects to address the existence of spatial associations and spatial dependence,and the predictive performances at different levels of sample sizes were analyzed in the assessment.The results showed that the models with random effects could account for a larger proportion of explainable variance(32.8%),and particularly the spatial random effect model provided the best predictive performances(R_(mean)^(2)=0.31),indicating that spatial random effects could substantially influence the results of the joint species distribution.Increasing sample size had a strong effect(R_(mean)^(2)=0.24-0.31)on the predictive accuracy of the spatially-structured model than on the other models,suggesting that optimal model selection should be dependent on sample size.This study highlights the importance of incorporating spatial random effects for JSDM predictions and suggests that the choice of model structures should consider the data quality across species.展开更多
The concentrations of V,Cr,Mn,Fe,Co,Ni,Cu,Zn,As,Mo,Cd,and Pb were determined in Doulonggang River,Xinyanggang River,Huangshagang River,Sheyanghe River,Guangaizongqu River,and Linhonghe River at the North of Jiangsu Pr...The concentrations of V,Cr,Mn,Fe,Co,Ni,Cu,Zn,As,Mo,Cd,and Pb were determined in Doulonggang River,Xinyanggang River,Huangshagang River,Sheyanghe River,Guangaizongqu River,and Linhonghe River at the North of Jiangsu Province in 2019.The annual average concentrations of V,Cr,Mn,Fe,Co,Ni,Cu,Zn,As,Mo,Cd and Pb in the six rivers were 2.20,1.22,4.53,21.9,0.13,2.79,1.77,4.00,2.97,3.87,0.01,0.19μg L^(-1)respectively.The highest concentration of most trace metals were found in Guangaizongqu River and Linhonghe River,and the lowest concentration were found in Xinyanggang River and Huangshagang River.The principal component analysis(PCA)resulted of two factors together explained 91.2%of the variance with>1initial eigenvalue,indicating that both natural and anthropogenic activities were contributing factors as the source of metal abundance in rivers of northern Jiangsu Province.The first major component represented the influence of anthropogenic activities,including industry and agriculture,with a contribution rate of 54.1%,affected Cr,Fe,Cu,Zn,Mo,Cd and Pb.The second(such as V,Mn,Co,Ni,As)was a mixed source,including the natural processes such as precipitation,erosion and weathering and anthropogenic action like industry and agriculture,with a contribution rate of 37.1%.Seasonal variations in trace metal concentrations were influenced by temperature,salinity,water discharge,and input of external pollutants.The highest concentrations were found in wet season and were strongly influenced by rainfall and seasonal industrial and agricultural activities.展开更多
Recurring Slope Lineae(RSL)are seasonally observed dark streaks on the Martian surface that exhibit distinct spatial and temporal distribution characteristics.Exploring their formation mechanisms can deepen our unders...Recurring Slope Lineae(RSL)are seasonally observed dark streaks on the Martian surface that exhibit distinct spatial and temporal distribution characteristics.Exploring their formation mechanisms can deepen our understanding of surface activity on Mars and provide scientific basis for future Mars exploration.This study aims to gain a comprehensive understanding of the spatial and temporal distribution characteristics and formation mechanisms of RSL by reviewing relevant literature and synthesizing various viewpoints and experimental results.RSL typically appear during warm seasons,disappear during cold seasons,and repeat over multiple Martian years.The formation mechanisms can be broadly categorized into three types:dry mode,wet mode,and mixed mode.However,a definitive explanation for the formation of RSL is still lacking,and both the dry and wet models have their respective limitations.It is likely that the formation of RSL is the result of the combined action of multiple mechanisms.The next step should be to search for terrestrial analogs of RSL and conduct research at high spatial and temporal resolutions to understand the forming processes of RSL.展开更多
We study a finite number of independent random walks with subexponentially distributed increments and negative drifts.We extend the one-dimensional results to finite and fully general stopping times.Assuming that the ...We study a finite number of independent random walks with subexponentially distributed increments and negative drifts.We extend the one-dimensional results to finite and fully general stopping times.Assuming that the distribution of the lengths of these intervals is relatively light compared to the distribution of the increments of the random walks,we derive the asymptotic tail distribution of the partial maximum sum over the random time interval.展开更多
Introducing a stoichiometric excess of lead iodide(PbI_(2))in perovskite films has been demonstrated as an effective passivation strategy that can improve the power conversion efficiency(PCE)of perovskite solar cells(...Introducing a stoichiometric excess of lead iodide(PbI_(2))in perovskite films has been demonstrated as an effective passivation strategy that can improve the power conversion efficiency(PCE)of perovskite solar cells(PSCs),However,excess PbI_(2)is also known to accelerate the degradation of the perovskite layer.In this study,we show that this degradation primarily stems from the decomposition of PbI_(2)at the bottom of the perovskite film which is exposed to light We further show that when using a two-step spin coating deposition procedure,the excess PbI_(2)results from the decomposition of the perovskite during the annealing process rather than the presence of non-reacted PbI_(2).Finally,we demonstrate that the spatial distribution of PbI_(2)within the perovskite films can be controlled in a way that mitigates the PbI_(2)induced perovskite decomposition.In this manner,we produced devices exhibiting initial power conversion efficiencies over 25%,maintaining 98.6% after 1000 h of maximum power point tracking under continuous illumination.These findings offer valuable insights into achieving high performance PSCs through judicious process control using a two-step spin-coating procedure.展开更多
基金supported by the Central Government Guidance Funds for Local Science and Technology Development Program(grant no.ZYYD2025ZY21)the Science and Technology Plan Project of the Xinjiang Production and Construction Corps(2023AB036)+1 种基金the Xinjiang Meteorological Bureau High-Level Key Talent Programthe Natural Science Foundation of the Xinjiang Uygur Autonomous Region(2023D01A17 and 2025D01A109).
文摘Low-visibility phenomena strongly impact the environment,as well as transportation,aviation and other fields that are closely related to people's livelihoods;thus,they represent important ecological issues of social concern.Based on observation data concerning low-visibility phenomena derived from 105 national meteorological stations in Xinjiang,China over the past 20 years,we systematically analyzed the differences between manual and instrument observations for six types of low-visibility phenomena,with a focus on exploring their spatiotemporal distribution characteristics using instrument data.The results revealed that low-visibility phenomena were dominated by fog-and haze-related events(mist,fog,and haze)in northern Xinjiang and dust-related events(dust storms,blowing sand,and floating dust)in southern Xinjiang,with transitional characteristics observed in eastern Xinjiang.Compared with manual observations,the instrument measurements significantly improved the fine-scale low-visibility phenomenon identification process.On the basis of the instrument observation data,spatial-dimension analysis results indicated that low-visibility phenomena in Xinjiang were significantly influenced by terrain factors.Constrained by the Tianshan Mountains,haze-like phenomena formed a core agglomeration area in northern Xinjiang,whereas dust-and sand-related phenomena radiated outward,with the Taklimakan Desert at the center.Moreover,the gripping effect of the terrain promoted dust transmission along low-altitude channels.Temporally,fog-and haze-related phenomena occurred mainly during autumn and winter,and the proportion of these events decreased from 76.7%to 55.1%.The fog-and haze-related phenomena demonstrated a U-shaped rebound trend,while the proportion of mist phenomena decreased by 34.2%.Dust storms occurred during spring,accounting for 23.3%to 44.9%of all storms.Instrument measurement technology has the advantages of high spatial and temporal resolutions and multiparameter coordination but provides a limited dust-haze mixed-pollution identification capacity.This study provides crucial reference data for enhancing the understanding of low-visibility events in Xinjiang and the potential responses while improving the accuracy of pollution source tracking and meteorological process diagnosis tasks.
基金supported by the National Key Research and Development Program of China(No.2019YFC1804501)the National Natural Science Foundation of China(Nos.42122056 and U1901210)+2 种基金Guangdong Basic and Applied Basic Research Foundation(No.2021B1515020063)the Key Research and Development Program of Guangdong Province(No.2021B1111380003)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01Z032).
文摘Coking industry is a potential source of heavy metals(HMs)pollution.However,its impacts to the groundwater of surrounding residential areas have not been well understood.This study investigated the pollution characteristics and health risks of HMs in groundwater nearby a typical coking plant.Nine HMs including Fe,Zn,Mo,As,Cu,Ni,Cr,Pb and Cd were analyzed.The average concentration of total HMswas higher in the nearby area(244.27μg/L)than that of remote area away the coking plant(89.15μg/L).The spatial distribution of pollution indices including heavy metal pollution index(HPI),Nemerow index(NI)and contamination degree(CD),all demonstrated higher values at the nearby residential areas,suggesting coking activity could significantly impact the HMs distribution characteristics.Four sources of HMs were identified by Positive Matrix Factorization(PMF)model,which indicated coal washing and coking emission were the dominant sources,accounted for 40.4%,and 31.0%,respectively.Oral ingestionwas found to be the dominant exposure pathway with higher exposure dose to children than adults.Hazard quotient(HQ)values were below 1.0,suggesting negligible non-carcinogenic health risks,while potential carcinogenic risks were from Pb and Ni with cancer risk(CR)values>10−6.Monte Carlo simulation matched well with the calculated results with HMs concentrations to be the most sensitive parameters.This study provides insights into understanding how the industrial coking activities can impact the HMs pollution characteristics in groundwater,thus facilitating the implement of HMs regulation in coking industries.
基金supported by the National Key Research and Development Program of China(No.2023YFC3706602)the National Natural Science Foundation of China(Nos.22225605 and 22193051)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0750200).
文摘Synthetic phenolic antioxidants(SPAs)are widely used in diverse industries due to their exceptional antioxidant characteristics.However,human exposure to SPAs may cause health problems.In this study,226 dust samples were collected from 10 provinces in China,and six SPAs(three parent SPAs and their three transformation products)were analyzed.The concentrations of6SPAs(the sum of six target compounds)ranged from 15.4 to 3210 ng/g(geometric mean(GM):169 ng/g).The highest concentration of6SPAswas found in Sichuan Province(GM:349 ng/g),which was approximately 4 times higher than that in Hubei Province(81.6 ng/g)(p<0.05).The concentrations of butylated hydroxytoluene(BHT),2,2'-methylene bis(4-methyl-6–tert-butylphenol)(AO2246),2,6-di–tert–butyl–1,4-benzoquinone(BHT-Q),2,6-di–tert–butyl–4-(hydroxymethyl)phenol(BHT-OH),and ∑_(p)-SPAs were substantially higher in dust from urban areas than rural areas(p<0.05).AO2246 concentration in dust from homes(GM:0.400 ng/g)was about 4 times higher than that in workplaces(0.116 ng/g)(p<0.01).Significantly higherp-SPAs concentrations were found in dust from homes(GM:17.5 ng/g)than workplaces(11.4 ng/g)(p<0.01).The estimated daily intakes(EDIs)of ∑_(6)SPAs exposed through dust ingestion were 0.582,0.342,0.197,0.076,and 0.080 ng/kg bw/day in different age groups,and exposed through dermal contact was 0.358,0.252,0.174,0.167,and 0.177 ng/kg bw/day.EDIs showed that the exposure risks of SPAs decreased with age.This is the first work to determine SPAs in dust from10 provinces in China and investigate the spatial distribution of SPAs in those regions.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(No.2019QZKK0605)the National Natural Science Foundation of China(No.42201161)the Startup Foundation for Introducing Talent of NUIST(No.2022r024)。
文摘Since scarce knowledge of soil mercury(Hg)concentrations and risks in the vulnerable Xinjiang,topsoils(0-15 cm)from its typical landscapes were extensively sampled.Topsoil total mercury(THg)concentrations varied broadly between 0.9 and 35.3 ng/g,of which16.8%exceeded the background value of soil Hg for Xinjiang.Topsoil THg concentrations across various landscapes exhibited a declining order:farmland(11.7±6.0 ng/g)>grassland(10.5±8.5 ng/g)>woodland(10.2±8.2 ng/g)>desert(7.0±5.8 ng/g).The average topsoil THg concentration was higher in northwestern Xinjiang(11.3±7.2 ng/g)than that in southeastern Xinjiang(6.3±6.1 ng/g).Relatively high topsoil THg concentrations were observed near the cities with intensive human activities,followed by a gradual decline to the surroundings.The concentrations of topsoil THg were strongly correlated with the contents of total organic carbon(TOC),clay,silty,and sandy,and the distance from each sampling site to its nearest city,suggesting that the variation of topsoil Hg was significantly influenced by TOC content,soil granularity,and anthropogenic Hg emissions.Silty and TOC were the principal affecting factors,explaining 48.7%and 7.9%of the THg variation,respectively.The contamination and potential ecological risk evaluations revealed that topsoils in regions with dense populations were polluted with Hg and contained higher potential ecological risks.The health risk evaluations indicated that exposure risks of topsoil Hg were higher for children than those for adults.Fortunately,topsoil Hg posed acceptable risks to human health.
基金supported by the National Natural Science Foundation of China(No.32260275)Fundamental Research Funds of CAF(CAFYBB2024ZA033)。
文摘Poyang Lake,China's largest freshwater lake,is a critical wintering ground for most of the global Siberian Grane(Grus leucogeranus)population.However,increasingly prolonged dry seasons have degraded the natural wetlands of Poyang Lake,forcing Siberian Cranes to shift to artificial habitats.From 2015 to 2023,field surveys revealed a substantial increase in the number of Siberian Cranes in artificial habitats,with peak counts reaching 3000individuals,accounting for up to 53%of the species'global population.Satellite telemetry of 13 individuals further confirmed the spatial use of these habitats,highlighting their consistent reliance on artificial sites over multiple years.Seven high-use hotspots were identified outside of Poyang Lake,including two artificial provisioning sites that supported dense foraging flocks for extended periods.Satellite telemetry confirmed this trend,with artificial habitats making up to 64.2%of the occurrence sites in some years.This reliance on artificial habitats was closely linked to the reduced tuber biomass in natural wetlands and low winter water levels in Poyang Lake,which collectively explained 83%of the variance in crane abundance in artificial habitats.Artificial habitat use peaked in December and January,indicating marked seasonal variation.Siberian Cranes also exhibited a pronounced circadian rhythm,foraging in artificial habitats during the day and returning to natural wetlands to roost at night.Despite the shift toward artificial habitats,natural wetlands remain critical for nighttime refuge.The continued dependence on artificial habitats raises concerns about disease transmission owing to dense congregations.Conservation strategies should prioritize both the careful management of artificial provisioning sites and the restoration of natural wetlands to improve food and habitat availability within natural ecosystems,ultimately enabling the return of Siberian Cranes to their traditional natural habitats.
基金supported by the National Natural Science Foundation of China(22078365,22478437)the Natural Science Foundation of Shandong Province(ZR2023MB076)。
文摘The synergy of metal/oxygen vacancy(O_(v))pairs is critical in catalyzing activation of C-H,C=C,and C-O bonds.However,gaining fundamental understanding on spatial distance of metallic and O_(v)sites on catalyst surface would lead to unexpected chemoselectivity toward important and challenging reactions.In this work,we have proposed and validated unique Ni-O-Ce-O_(v)enriched Ni/CeO_(2)catalysts prepared by a deposition-precipitation method,for the transfer hydrogenation of lignin-derived guaiacol toward cyclohexanol rather than benzene derivatives.The counter-intuitively designed high Ni loading Ni_(2)0/CeO_(2)catalyst(20 wt%Ni content)displays a distance of 0.5 nm for Ni/O_(v)pairs with a remarkable activity(TOF:166.5 h^(-1))and 90%+selectivity for C_(Ar)=C_(Ar)bond saturation,outperforming better metal-dispersed Ni_(5)/CeO_(2)catalyst with limited presence of Ni-O-Ce-O_(v)sites.The high hydrogenation activity against hydrogenolysis reactions on Ni_(2)0/CeO_(2)catalyst is attributed to tunable Ni/O_(v)distances,which constrain the cleavage of CAr-OH bond and deep deoxygenation.Such spatial distribution effect has also facilitated tandem dehydrogenation(O-H bond cleavage)and hydrogenation(C_(Ar)=C_(Ar)hydrogenation)reactions,leading to cyclohexanol as the target product in the absence of externally added H_(2).Insights into spatial distribution of O_(v)sites open an alternative perspective in designing efficient catalysts toward producing value-added cyclic oxygenates through upgrading of lignin compounds.
基金National Natural Science Foundation of China,No.41907382China Postdoctoral Science Foundation,No.2019M652520Henan Postdoctoral Science Foundation,No.201902025。
文摘This paper selects sampling sections for the mainstream and tributaries of the middle and lower reaches of the Yellow River,collects river water and sediment samples during the flood season for pollen analysis,and uses methods such as Geodetector to explore the distribution characteristics and influencing factors of pollen.The results show significant variations in vegetation composition across different watersheds,leading to notable differences in both the percentage and concentration of pollen types.Pollen concentration in river water is generally higher in the mainstream compared to tributaries,while sediment pollen percentage and concentration are typically lower in the mainstream than in tributaries.The concentration of suspended solids is the most significant factor affecting pollen concentration in the Yellow River,with this effect being particularly prominent outside the Shanxi-Shaanxi Gorge.Abundant coarse sand and rapid flow velocities are likely responsible for the high suspended solids concentration and lower pollen concentration observed in the mainstream of the Shanxi-Shaanxi Gorge.In sediments,clay content is the primary factor influencing pollen concentration,and its interaction with silt and flow velocity has a more prominent influence on pollen concentration.At the Yellow River section below the Shanxi-Shaanxi Gorge,sediment pollen and clay concentrations significantly increase.The changes in pollen concentration in the river water before and after the reservoir are consistent with the suspended solids concentration,while the changes in sediment pollen concentration are consistent with the clay content.Notably,pollen concentrations in sediments decrease more significantly after passing through a reservoir compared to changes observed in river water samples.Overall,there is a strong correlation between river pollen and topsoil pollen,which can provide a reliable reflection of the broader vegetation landscape of the watershed.The findings can provide support for paleoenvironmental reconstruction using pollen from alluvial sediments or lakes with river inflows.
基金supported by the China National Key Research and Development Plan(2022YFB2902605)the Beijing Natural Science Foundation(4252008)+2 种基金the 13th 5-Year Plan Civil Aerospace Technology Advance Research Project(D030301)the Hebei Province High-level Talent Funding Project(B2021003032)the New Technology Research University Cooperation Project(SKX212010010).
文摘The space-air-ground integrated network(SAGIN)is an important sixth-generation(6G)scenario that is enabled by dynamic spot beam forming by a phased array antenna(PAA).The extremely high mobility of satellites and more complicated radio resource control(RRC)have brought introduced a new challenge,and the issue of determining appropriate moments and procedures for executing handover(HO)for all users in a coverage area is urgent.The existing research considers the users as an entirety,and it determines the HO moment under the assumption that all of the satellite subpoints(SSP)pass through the centre of the cell.However,when using this scheme,the HO failure ratio(HOFR)would experience great degradation caused by the imbalance between the unified HO moments and the uncertain spatial distribution of users’(SDU)spatial-temporal variation.This paper proposes a novel HO moment determination method for a low-orbit satellite internet network(LEO-SIN).The rules of SDU variance under SSP motion are first proposed,and they calculate dynamic UE requests within the constraints of the footprint boundary and with SSP motions.Then,we first formulate the problems of multiuser-directed graphs for HO moment determination and prove that it is a nondeterministic polynomial-time(NP)hard problem.An animal survival algorithm based on the Dingo of algorithm(DOA)is proposed to solve the above problems.Multiuser fused directed graphs are first designed to determine HO moments based on the rules of SDU variation and the animal survival algorithm.The simulations show that the proposed method has a better HO performance for LEO-SIN.
基金the Science and Technology Research Project of Shandong Meteorological Bureau(2022SDQN11)Science and Technology Research Project of Yantai Meteorological Bureau(2024ytcx07).
文摘Based on the monitoring data of PM 10 concentration from six environmental monitoring stations and the ground meteorological observation data in Yantai City from 2019 to 2021,the spatial and temporal variation of PM 10 concentration and its relationship with meteorological factors were studied.The results show that from the perspective of temporal variation,the annual average of PM 10 concentration in Yantai City tended to decrease year by year.It was high in winter and spring and low in summer and autumn.In terms of monthly variation,the changing curve is U-shaped,and it was high in December and January but low in July and August.During a day,PM 10 concentration had two peaks.The first peak appeared approximately from 09:00 to 11:00,and the second peak can be found from 21:00 to 23:00.From the perspective of spatial distribution,PM 10 concentration was the highest in the development area and Fushan District.It was the highest in the west,followed by the east,while it was the lowest in the middle.The spatial difference rate was the highest in summer.Average temperature,relative humidity,wind speed and precipitation were the main meteorological factors influencing PM 10 concentration in Yantai area.PM 10 concentration was negatively correlated with average temperature and relative humidity,and the correlation was the most significant from June to October.It was negatively correlated with wind speed and precipitation,and the correlation was different in various months.The negative correlation was significant in summer and winter.
基金supported by the National Natural Science Foundation of China(Nos.U19A2044,42105132,42030609,41975037,and 42105133)the National Key Research and Development Program of China(No.2022YFC3703502)+1 种基金the Plan for Anhui Major Provincial Science&Technology Project(No.202203a07020003)Hefei Ecological Environment Bureau Project(No.2020BFFFD01804).
文摘As a significant city in the Yangtze River Delta regions,Hefei has experienced rapid changes in the sources of air pollution due to its high-speed economic development and urban expansion.However,there has been limited research in recent years on the spatial-temporal distribution and emission of its atmospheric pollutants.To address this,this study conducted mobile observations of urban roads using the Mobile-DOAS instrument from June 2021 to May 2022.The monitoring results exhibit a favourable consistent with TROPOMI satellite data and ground monitoring station data.Temporally,there were pronounced seasonal variations in air pollutants.Spatially,high concentration of HCHO and NO_(2)were closely associated with traffic congestion on roadways,while heightened SO_(2)levels were attributed to winter heating and industrial emissions.The study also revealed that with the implementation of road policies,the average vehicle speed increased by 95.4%,while the NO concentration decreased by 54.4%.In the estimation of urban NO_(x)emission flux,it was observed that in temporal terms,compared with inventory data,the emissions calculated viamobile measurements exhibitedmore distinct seasonal patterns,with the highest emission rate of 349 g/sec in winter and the lowest of 142 g/sec in summer.In spatial terms,the significant difference in emissions between the inner and outer ring roads also suggests the presence of the city’s primary NO_(x)emission sources in the area between these two rings.This study offers data support for formulating the next phase of air pollution control measures in urban areas.
基金funded by the National Key R&D Program of China(Grant no.2022YFC2807504)the Marine S&T Fund of Shandong Province for Qingdao Marine Science and Technology Center(Grant no.2022QNLM030002-1)the Central Public-interest Scientific Institution Basal Research(Grant no.2023TD02).
文摘Antarctic krill(Euphausia superba),widely distributes around Antarctica,is a key species supporting the biodiversity of the Southern Ocean ecosystem.The Commission for the Conservation of Antarctic Marine Living Resources(CCAMLR)has thus managed the krill fishery according to a precautionary way.Currently,CCAMLR is making effort to develop a refined krill fishery management approach based on more solid science,which requires accurate predictions of krill distribution.To address this need,this study investigated the effects of algorithm and spatial resolution on the performance of Antarctic krill distribution modelling.We integrated acoustic data from 4 surveys conducted in the waters adjacent to the Antarctic Peninsula with 11 environmental variables characterizing krill prey conditions,water mass properties,and seafloor topography.These data were processed at 4 spatial resolutions(5,10,15,and 20 km)to fit distribution models using 4 algorithms:Random Forests(RF),Generalized Additive Models(GAM),Extreme Gradient Boosting(XGBoost),and Artificial Neural Networks(ANN).Model performance was assessed and compared in terms of goodness-of-fit and predictive accuracy.The results showed that RF achieved the highest predictive performance at most resolutions,whereas GAM performed best at the coarsest resolution(20 km).XGBoost closely following RF in accuracy and demonstrated robustness as evidenced by the highly consistent partial dependence curves across resolutions.In contrast,ANN exhibited limitations with smaller sample sizes,resulting in comparatively poorer predictive performance.The analysis revealed a trade-off whereby reducing spatial resolution improved model fit and mitigated zero-inflation at the expense of fine-scale information and overall predictive accuracy.Ensemble models,integrating RF,GAM,and XGBoost,are proposed as potential balanced solutions to improve predictive stability,offering a more robust scientific basis for the refinement of krill management.
基金The National Key Research and Development Program of China,No.2021YFE0190100Inner Mongolia Autonomous Region Mongolian Medicine Standardization Project,No.2023-[MB023]The Earmarked Fund for CARS,No.CARS-21。
文摘Medicinal plant diversity(MPD)is an indispensable part of global plant diversity,serving as the foundation for human survival by offering remedies and preventive measures against diseases.However,factors such as overexploitation,competition from invasive alien species,and climate change,threaten the habitats of medicinal plants,necessitating a comprehensive understanding of their spatial distribution and suitable habitats.We leveraged a decade of field survey data on medicinal plant distribution in the Yinshan Mountains,combined with spatial analysis,species distribution modeling,and the Carnegie Ames Stanford Approach(CASA)to explore the MPD spatial distribution and suitable habitats.Spatial analysis revealed that the central and eastern parts of Yinshan Mountains were the primary MPD hotspots,with no cold spots evident at various spatial scales.As the spatial scale decreased,previous non-significant regions transformed into hotspots,with instances where large-scale hotspots became insignificant.These findings offer valuable guidance for safeguarding and nurturing MPD across diverse spatial scales.In future climate change scenarios within the shared socioeconomic pathways(SSP),the habitat suitability for MPD in the Yinshan Mountains predominantly remains concentrated in the central and eastern regions.Notably,areas with high net primary productivity(NPP)values and abundant vegetation coverage align closely with MPD habitat suitability areas,potentially contributing to the region's rich MPD.
基金China Institute of Water Resources and HydropowerResearch(IWHR)Innovative Team for Theoreticaland Technological Research on EcologicalLandscape Construction of Urban and Rural WaterSystems,Grant/Award Number:WE0145B042021。
文摘Located in Nanhai Town,Songzi City,Hubei Province,Xiaonanhai Lake is the largest natural lake in Songzi.It was once severely polluted due to the discharge of urban and rural domestic sewage,disorderly development of agricultural planting,unregulated aquaculture,and poultry farming.However,relevant esti-mations of the pollutant content in its sediment have not been carried out.This study analyzed the spatial patterns of heavy metal pollution and eutrophication at 36 water sampling sites in the Xiaonanhai Lake area,focusing on eight heavy metals:Cd,Cr,Cu,Ni,As,Pb,Hg,and Zn.The nutrient status of the lake area was evaluated using the nitrogen-phosphorus comprehensive pollution index,and heavy metal pollution status of the lake area was evaluated using geo-accumulation and the potential ecological risk index.Spatial autocorrelation analysis revealed the spatial correlation and aggregation of eutrophication levels in Xiaonanhai Lake.The results showed that the overall trophic state of the Xiaonanhai Lake area was moderate eutrophication,with a gradually decreasing eutrophication level from north to south.The Chengnan Wastewater Treatment Plant in the northern part of the lake area and surface source pollution from aquaculture were the main nitrogen and phosphorus sources.The overall eco-logical risk index of heavy metal pollution was medium and gradually weakened from north to south,consistent with the thickness of the bottom mud.The heavy metal pollution load was mainly precipitated from the bottom mud in the lake area.The eutrophication and heavy metal pollution levels in the lake area showed significant positive spatial autocorrelation,the influence range of the regional eutrophication level was small,and the spatial heterogeneity of the eutrophication and heavy metal pollution levels in Xiaonanhai Lake was relatively high.The northern part of the lake was a hotspot(high/high aggregation)of eutrophication(p<0.01)while the southern part was a cold spot(low/low concentration;p<0.05).The middle and northern part of the lake area was the hot spot(high/high concentration)of heavy metal pollution level(p<0.1)while the southern part was the cold spot(low/low concentration;p<0.1).Therefore,when carrying out water environment management in Xiaonanhai Lake,the northern area and the middle area should be prioritized for eutrophication prevention and control and dredging.
基金financially supported by the National Natural Science Foundation of China(Nos.22272118,22172111 and 22309134)the Science and Technology Commission of Shanghai Municipality,China(Nos.22ZR1464100,20ZR1460300 and 19DZ2271500)+3 种基金China Postdoctoral Science Foundation(2022M712402)Shanghai Rising-Star Program(23YF1449200)Zhejiang Provincial Science and Technology Project(2022C01182)the Fundamental Research Funds for the Central Universities(22120210529 and 2023-3-YB-07)。
文摘Compared with Zn^(2+),the current mainly reported charge carrier for zinc hybrid capacitors,small-hydrated-sized and light-weight NH_(4)^(+)is expected as a better one to mediate cathodic interfacial electrochemical behaviors,yet has not been unraveled.Here we propose an NH_(4)^(+)-modulated cationic solvation strategy to optimize cathodic spatial charge distribution and achieve dynamic Zn^(2+)/NH_(4)^(+)co-storage for boosting Zinc hybrid capacitors.Owing to the hierarchical cationic solvated structure in hybrid Zn(CF_(3)SO_(3))_(2)–NH_4CF_(3)SO_(3)electrolyte,high-reactive Zn^(2+)and small-hydrate-sized NH_4(H_(2)O))(4)^(+)induce cathodic interfacial Helmholtz plane reconfiguration,thus effectively enhancing the spatial charge density to activate 20%capacity enhancement.Furthermore,cathodic interfacial adsorbed hydrated NH_(4)^(+)ions afford high-kinetics and ultrastable C···H(NH_(4)^(+))charge storage process due to a much lower desolvation energy barrier compared with heavy and rigid Zn(H_(2)O)_6^(2+)(5.81 vs.14.90 eV).Consequently,physical uptake and multielectron redox of Zn^(2+)/NH_(4)^(+)in carbon cathode enable the zinc capacitor to deliver high capacity(240 mAh g^(-1)at 0.5 A g^(-1)),large-current tolerance(130 mAh g^(-1)at 50 A g^(-1))and ultralong lifespan(400,000cycles).This study gives new insights into the design of cathode–electrolyte interfaces toward advanced zinc-based energy storage.
基金National Natural Science Foundation of China(12125509,11961141003,12275361,U2267205,12175152,12175121)National Key Research and Development Project(2022YFA1602301)Continuous-support Basic Scientific Research Project。
文摘To generate a neutron beam exhibiting a Maxwellian energy distribution with narrow emission angles for measuring the neutron capture reaction rates of the s-process nuclides,a monoenergetic 3.4 MeV proton beam produced by the tandem-accelerator in the China Institute of Atomic Energy was utilized.The proton beam was first transmitted through a 60.5μm aluminum foil and then impinged on a natural LiF target to produce neutron beam via^(7)Li(p,n)7Be reaction.The quasi-Gaussian energy distribution of protons in the LiF target resulted in neutron energy spectra that agreed with a Maxwellian energy distribution at kT=(22±2)keV,which was achieved by integrating neutrons detected within an emission angle of 65.0°±2.6°using a ^(6)Li glass detector positioned at 65°relative to the proton beam direction.The narrow angular spread of the Maxwelliandistributed neutron beam enables direct measurement of neutron capture cross-sections for most s-process nuclides,overcoming previous experimental limitations associated with broad angular distributions.
基金supported by the National Key R&D Program of China(No.2022YFD2401301)。
文摘Species distribution patterns is one of the important topics in ecology and biological conservation.Although species distribution models have been intensively used in the research,the effects of spatial associations and spatial dependence have been rarely taken into account in the modeling processes.Recently,Joint Species Distribution Models(JSDMs)offer the opportunity to consider both environmental factors and interspecific relationships as well as the role of spatial structures.This study uses the HMSC(Hierarchical Modelling of Species Communities)framework to model the multispecies distribution of a marine fish assemblage,in which spatial associations and spatial dependence is deliberately accounted for.Three HMSC models were implemented with different structures of random effects to address the existence of spatial associations and spatial dependence,and the predictive performances at different levels of sample sizes were analyzed in the assessment.The results showed that the models with random effects could account for a larger proportion of explainable variance(32.8%),and particularly the spatial random effect model provided the best predictive performances(R_(mean)^(2)=0.31),indicating that spatial random effects could substantially influence the results of the joint species distribution.Increasing sample size had a strong effect(R_(mean)^(2)=0.24-0.31)on the predictive accuracy of the spatially-structured model than on the other models,suggesting that optimal model selection should be dependent on sample size.This study highlights the importance of incorporating spatial random effects for JSDM predictions and suggests that the choice of model structures should consider the data quality across species.
基金funded by the National Natural Science Foundation of China(Nos.42130410)the Joint Fund between NSFC and Shandong Province(No.U1906210)。
文摘The concentrations of V,Cr,Mn,Fe,Co,Ni,Cu,Zn,As,Mo,Cd,and Pb were determined in Doulonggang River,Xinyanggang River,Huangshagang River,Sheyanghe River,Guangaizongqu River,and Linhonghe River at the North of Jiangsu Province in 2019.The annual average concentrations of V,Cr,Mn,Fe,Co,Ni,Cu,Zn,As,Mo,Cd and Pb in the six rivers were 2.20,1.22,4.53,21.9,0.13,2.79,1.77,4.00,2.97,3.87,0.01,0.19μg L^(-1)respectively.The highest concentration of most trace metals were found in Guangaizongqu River and Linhonghe River,and the lowest concentration were found in Xinyanggang River and Huangshagang River.The principal component analysis(PCA)resulted of two factors together explained 91.2%of the variance with>1initial eigenvalue,indicating that both natural and anthropogenic activities were contributing factors as the source of metal abundance in rivers of northern Jiangsu Province.The first major component represented the influence of anthropogenic activities,including industry and agriculture,with a contribution rate of 54.1%,affected Cr,Fe,Cu,Zn,Mo,Cd and Pb.The second(such as V,Mn,Co,Ni,As)was a mixed source,including the natural processes such as precipitation,erosion and weathering and anthropogenic action like industry and agriculture,with a contribution rate of 37.1%.Seasonal variations in trace metal concentrations were influenced by temperature,salinity,water discharge,and input of external pollutants.The highest concentrations were found in wet season and were strongly influenced by rainfall and seasonal industrial and agricultural activities.
基金Supported by the National Natural Science Foundation(No.42272340).
文摘Recurring Slope Lineae(RSL)are seasonally observed dark streaks on the Martian surface that exhibit distinct spatial and temporal distribution characteristics.Exploring their formation mechanisms can deepen our understanding of surface activity on Mars and provide scientific basis for future Mars exploration.This study aims to gain a comprehensive understanding of the spatial and temporal distribution characteristics and formation mechanisms of RSL by reviewing relevant literature and synthesizing various viewpoints and experimental results.RSL typically appear during warm seasons,disappear during cold seasons,and repeat over multiple Martian years.The formation mechanisms can be broadly categorized into three types:dry mode,wet mode,and mixed mode.However,a definitive explanation for the formation of RSL is still lacking,and both the dry and wet models have their respective limitations.It is likely that the formation of RSL is the result of the combined action of multiple mechanisms.The next step should be to search for terrestrial analogs of RSL and conduct research at high spatial and temporal resolutions to understand the forming processes of RSL.
基金supported by Xinjiang Normal University Outstanding Young Teacher Research Launch Fund Project(Grant No.XJNU202116)。
文摘We study a finite number of independent random walks with subexponentially distributed increments and negative drifts.We extend the one-dimensional results to finite and fully general stopping times.Assuming that the distribution of the lengths of these intervals is relatively light compared to the distribution of the increments of the random walks,we derive the asymptotic tail distribution of the partial maximum sum over the random time interval.
基金funding support from the National Key R&D Program of China(2021YFF0501900)the Excellent Young Scholar Fund from the National Natural Science Foundation of China(22122903)+1 种基金the Tianjin Distinguished Young Scholar Fund(20JCJQJC00260)support from the Tianchi Talent Program of Xinjiang Uygur Autonomous Region。
文摘Introducing a stoichiometric excess of lead iodide(PbI_(2))in perovskite films has been demonstrated as an effective passivation strategy that can improve the power conversion efficiency(PCE)of perovskite solar cells(PSCs),However,excess PbI_(2)is also known to accelerate the degradation of the perovskite layer.In this study,we show that this degradation primarily stems from the decomposition of PbI_(2)at the bottom of the perovskite film which is exposed to light We further show that when using a two-step spin coating deposition procedure,the excess PbI_(2)results from the decomposition of the perovskite during the annealing process rather than the presence of non-reacted PbI_(2).Finally,we demonstrate that the spatial distribution of PbI_(2)within the perovskite films can be controlled in a way that mitigates the PbI_(2)induced perovskite decomposition.In this manner,we produced devices exhibiting initial power conversion efficiencies over 25%,maintaining 98.6% after 1000 h of maximum power point tracking under continuous illumination.These findings offer valuable insights into achieving high performance PSCs through judicious process control using a two-step spin-coating procedure.
