Clean energy and a sustainable environment are grand challenges that the world is facing which can be addressed by converting solar energy into transportable and storable fuels(chemical fuel).The main scientific and t...Clean energy and a sustainable environment are grand challenges that the world is facing which can be addressed by converting solar energy into transportable and storable fuels(chemical fuel).The main scientific and technological challenges for efficient solar energy conversion,energy storage,and environmental applications are the stability,durability,and performance of low-cost functional materials.Among different nanomaterials,perovskite type LaFeO_(3)has been extensively investigated as a photocatalyst due to its abundance,high stability,compositional and structural fexibility,high electrocatalytic activity,efficient sunlight absorption,and tunable band gap and band edges.Hence,it is urgent to write a comprehensive review to highlight the trend,challenges,and prospects of LaFeO_(3)in the field of photocatalytic solar energy conversion and environment purification.This critical review summarizes the history and basic principles of photocatalysis.Further,it reviews in detail the LaFeO_(3),applications,shortcomings,and activity enhancement strategies including the design of nanostructures,elemental doping,and heterojunctions construction such as Type-I,Type-II,Z-Type,and uncommon heterojunctions.Besides,the optical and electronic properties,charge carriers separation,electron transport phenomenon and alignment of the band gaps in LaFeO_(3)-based heterostructures are comprehensively discussed.展开更多
A typical Z-scheme system is composed of two photocatalysts which generate two sets of charge carriers and split water into H2 and O2 at different locations.Scientists are struggling to enhance the efficiencies of the...A typical Z-scheme system is composed of two photocatalysts which generate two sets of charge carriers and split water into H2 and O2 at different locations.Scientists are struggling to enhance the efficiencies of these systems by maximizing their light absorption,engineering more stable redox couples,and discovering new O2 and H2 evolutions co-catalysts.In this work,Au decorated WO3/g-C3N4 Z-scheme nanocomposites are fabricated via wet-chemical and photo-deposition methods.The nanocomposites are utilized in photocatalysis for H2 production and 2,4-dichlorophenol(2,4-DCP)degradation.It is investigated that the optimized 4Au/6%WO3/CN nanocomposite is highly efficient for production of 69.9 and 307.3μmol h−1 g−1 H2 gas,respectively,under visible-light(λ>420 nm)and UV–visible illumination.Further,the fabricated 4Au/6%WO3/CN nanocomposite is significant(i.e.,100%degradation in 2 h)for 2,4-DCP degradation under visible light and highly stable in photocatalysis.A significant 4.17%quantum efficiency is recorded for H2 production at wavelength 420 nm.This enhanced performance is attributed to the improved charge separation and the surface plasmon resonance effect of Au nanoparticles.Solid-state density functional theory simulations are performed to countercheck and validate our experimental data.Positive surface formation energy,high charge transfer,and strong non-bonding interaction via electrostatic forces confirm the stability of 4Au/6%WO3/CN interface.展开更多
Soaring bird migration often relies on suitable terrain and airflow;therefore,route selection is vital for successful migration.While age and experience have been identified as key factor influencing migration route s...Soaring bird migration often relies on suitable terrain and airflow;therefore,route selection is vital for successful migration.While age and experience have been identified as key factor influencing migration route selection among soaring raptors in the African-Eurasian Flyway,how they shape the migration route of soaring raptors in East Asia is still largely unknown.In this study,we investigated potential variations in the routes and timing in autumn migration of juvenile and older soaring birds,using count data of Greater Spotted Eagles(Clanga clanga)from two coastal sites and two inland sites in China.From 2020 to 2023,we recorded a total of 340 individuals,with the highest site averaging over 90 individuals per autumn,making it one of the world’s top single-season counts and thus a globally important site for this species.We found that 82% and 61% records from coastal sites were juveniles,significantly higher than inland sites(15% and 24%).Juveniles at all four sites exhibited markedly earlier median passage time than non-juveniles,with brief overlapping in their main migration periods.Both coastal sites are located on the tip of peninsulas stretching southwest,requiring long overwater flights if crossing the Bohai Bay or Beibu Gulf,which would be energetically demanding and increase mortality risk.Experienced individuals may have learned to avoid such terrain and subsequent detour,while juveniles are more prone to enter these peninsulas due to lack of experience and opportunities for social learning,or following other raptor species that are more capable of powered flight.Our findings highlight the importance of age and experience in migration route selection of large soaring birds.展开更多
The photocatalytic performance of g-C_(3)N_(4) for CO_(2) conversion is still inadequate by several shortfalls including the instability,insu cient solar light absorption and rapid charge carrier's recombination r...The photocatalytic performance of g-C_(3)N_(4) for CO_(2) conversion is still inadequate by several shortfalls including the instability,insu cient solar light absorption and rapid charge carrier's recombination rate. To solve these problems,herein,noble metals(Pt and Au)decorated Sr-incorporated g-C_(3)N_(4) photocatalysts are fabricated via the simple calcination and photo-deposition methods. The Sr-incorporation remarkably reduced the g-C_(3)N_(4) band gap from 2.7 to 2.54 eV,as evidenced by the UV–visible absorption spectra and the density functional theory results. The CO_(2) conversion performance of the catalysts was evaluated under visible light irradiation. The Pt/0.15 Sr-CN sample produced 48.55 and 74.54 μmol h-1 g-1 of CH_(4) and CO,respectively.These amounts are far greater than that produced by the Au/0.15 Sr-CN,0.15 Sr-CN,and CN samples. A high quantum e ciency of 2.92% is predicted for the Pt/0.15 Sr-CN sample. Further,the stability of the photocatalyst is confirmed via the photocatalytic recyclable test. The improved CO_(2) conversion performance of the catalyst is accredited to the promoted light absorption and remarkably enhanced charge separation via the Sr-incorporated mid gap states and the localized surface plasmon resonance e ect induced by noble metal nanoparticles.This work will provide a new approach for promoting the catalytic e ciency of g-C_(3)N_(4) for e cient solar fuel production.展开更多
Global climate changes have significantly affected tree growth and forest structures and functions in some arid and semi-arid regions,which are becoming warmer and wetter.Due to natural factors such as climate and ter...Global climate changes have significantly affected tree growth and forest structures and functions in some arid and semi-arid regions,which are becoming warmer and wetter.Due to natural factors such as climate and terrain,some tree species may form different forest patches at the edges of their distribution areas.However,how forest patches of various sizes respond to climate change is unclear.In this study,we collected 203 tree cores from six different sizes of forest patches at the edge of the distribution area of Picea crassifolia Kom.in the northeast Tibetan Plateau.And we used the dendrochronology method to study the response of tree growth and resilience in different forest patches to climate change from 1961 to 2020.We simultaneously measured the contents of nonstructural carbohydrates(NSC),total nitrogen and total phosphorus of tree needles.Our results showed that the growth of trees in small-and medium-size forest patches(0.8–18.6 ha)has increased significantly.The early growing season(May–July)minimum temperature was the most important climate factor driving the growth of small-and medium-sized patch trees.The early growing season maximum temperature was the most important climate factor that inhibited the growth of trees in the largest patches(362.8 ha).The growth of individual trees in medium forest patches was better and the correlation with annual minimum temperature,maximum temperature,precipitation,actual evapotranspiration,and palmer drought severity index was stronger.The higher NSC content,stronger photosynthesis,and higher nitrogen utilization efficiency in leaves might be one of the reasons for the better growth of trees in moderate forest patches.In extreme drought years,as the forest patch area increased,the overall trend of tree growth resistance showed a unimodal pattern,with the highest at a forest patch area of 7.1 ha,while the overall trend of tree growth recovery was opposite.Therefore,we should strengthen the management of trees in large forest patches to cope with climate change.展开更多
Lake-level changes can significantly affect paleoenvironmental evolution,resource occurrence,terrestrial carbon budget,and biodiversity in continental basins.Climate is one of the most critical factors controlling lak...Lake-level changes can significantly affect paleoenvironmental evolution,resource occurrence,terrestrial carbon budget,and biodiversity in continental basins.Climate is one of the most critical factors controlling lake-level changes.Paleoclimate of the Early Jurassic has been evidenced by oscillating icehouses to(super)greenhouses with interrupted intermittent extreme climatic events(hyperthermal and cooling),e.g.,the Toarcian oceanic anoxic event(~183 Ma)and the late Pliensbachian cooling event(~185 Ma).Lake-level evolution and hydrologic cycling on Earth’s surface during the Early Jurassic icehouses-to-(super)greenhouses are thus far poorly understood due to a lack of continuous high-resolution nonmarine evidence.Here we present a super-long nonmarine lake level record for this pivotal interval from the early Pliensbachian to Toarcian by sedimentary noise modeling,and construct a 16.7-Myr-long astronomical time scale(174.2 Ma to 190.9 Ma)based on cyclostratigraphy analysis of rock color datasets(CIE b*)of the Qaidam Basin.Our results document lake-level oscillations on a 5-to 10-million-year(Myr)scale which shows a pronounced correlation with long-term climate variation and extreme climatic events,and 1-to 2.5-Myr-scale lake-level changes that are prominently paced by the 2.4-Myr long-eccentricity forcing and the 1.2-Myr obliquity forcing.At the Pliensbachian Stage,the 1.2-Myr-scale lake-level changes are in phase with the coeval sealevel variations.Orbitally forced growth and decay of the ephemeral or permanent ice sheets in polar regions are interpreted to control the synchronous ups-and-downs of continental lake level and global sea level.However,during the Toarcian ice-free greenhouses to(super)greenhouses,the 1.2-Myr-scale lake-level variations show an anti-phase relationship with global sea level,indicating a‘seesaw’interaction between continental reservoirs(lakes and groundwater)and global oceans.The 2.4-Myr longeccentricity cycles mainly regulate variations of lake level and sea level by controlling the growth and decay of small-scale continental ice sheets,which is especially notable during the Pliensbachian Stage.These findings indicate a remarkable transition of hydrological cycling pattern during the Pliensbachian-Toarcian icehouses to(super)greenhouses,which provides new perspectives and evidence for investigating the hypothesis of global sea-level changes(e.g.,glacio-eustasy and aquifer-eustasy)and long-period astronomical forcing in nonmarine stratigraphy.展开更多
Phase change materials(PCMs)have remarkable energy storage capacity and promising applications in the field of thermal control of electronic products.The problem of thermal property improvement and heat transfer of PC...Phase change materials(PCMs)have remarkable energy storage capacity and promising applications in the field of thermal control of electronic products.The problem of thermal property improvement and heat transfer of PCMs in metal-foam heatsinks is an important task for thermal management of electronic components.Mixed paraffin samples were prepared by mixing appropriate proportions of paraffin(mass)at various temperatures.Differential scanning calorimetry analysis revealed that the maximum enthalpy of 206.3 J/g is obtained by mixing 20%of 17°C liquid paraffin and 80%of 29℃ solid paraffin.Heating and cooling cycling tests revealed that mixed paraffin exhibits excellent thermal stability and that the regulation method marginally affects thermal stability.Moreover,composites were prepared by embedding PCM into a copper foam by melt impregnation.The thermal conductivity of the composites increased to 4.35 W/(m K),corresponding to 20 times its original value.In addition,density functional theory and experimental results were in good agreement,indicating that the regulation method is practical and effective.展开更多
The silver Y moth Autographa gamma undertakes windbome spring and fall migrations between winter breeding re- gions around the Mediterranean and summer breeding regions in northern Europe. Flight behaviors facilitatin...The silver Y moth Autographa gamma undertakes windbome spring and fall migrations between winter breeding re- gions around the Mediterranean and summer breeding regions in northern Europe. Flight behaviors facilitating these migrations include: (i) selection of seasonally-favorable tailwinds; (ii) flying at the altitude of the fastest winds; (iii) adopting flight headings that partially counteract crosswind drift; and (iv) seasonal reversal of preferred directions between spring and fall. In the UK, ra- dar measurements indicate that migratory activity is pronounced during the spring and fall, but is usually very low during mid- summer (July). However, an atypically intense period of high-altitude flight was recorded during July 2006, and in this study we compare the flight behavior of A. gamma during these midsummer movements with the more typical spring and fall migrations. During July 2006, activity was most intense at significantly lower altitudes than occurred in spring or fall, and was not associated with the height of the fastest winds; consequently displacement speeds were significantly slower. The most striking difference was an absence of tailwind selectivity in July with windborne movements occurring on almost every night of the month and on tailwinds from all directions. Finally, orientation behavior was quantitatively different during July, with significantly greater dis- persion of flight headings and displacements than observed in spring and fall. We discuss mechanisms which could have caused these differences, and conclude that a lack of appropriate photopcriod cues during development of the summer generation resulted in randomly-oriented 'dispersive' movements that were strikingly different from typical seasonal migrations .展开更多
Accurately quantifying rates of soil erosion requires capturing both the volumetric nature of the visible,convergent fluvial pathways(also known as rills)and the subtle nature of the less-visible,diffuse pathways(inte...Accurately quantifying rates of soil erosion requires capturing both the volumetric nature of the visible,convergent fluvial pathways(also known as rills)and the subtle nature of the less-visible,diffuse pathways(interrill areas).The aim of this study was to use Rare Earth Oxide(REO)tracers and Structure-from-Motion(SfM)photogrammetry to elucidate retrospective information about soil erosion rates and sediment sources during different soil erosion conditions,within a controlled laboratory environment.The experimental conditions created erosion events consistent with diffuse and convergent erosion processes.REO tracers allowed the sediment transport distances of over 2 m to be described,and helped resolved the relative contribution of diffuse and convergent soil erosion;interrill areas were also iden-tified as a significant sediment sources soil loss under convergent erosion conditions.While the potential for SfM photogrammetry to resolve sub-millimetre elevations changes was demonstrated,under some conditions non-erosional changes in surface elevation,such as compaction,exceeded volumes of soil loss via diffuse erosion.The discrepancies between SfM Photogrammetry calculations and REO tagged sediment export were beneficial,identifying that during soil erosion events sediment in both aggregate and particle form is deposited within the convergent features,even when the rill extended the full length of the soil surface.The combination of SfM photogrammetry and REO tracers has provided a novel platform for building a spatial understanding of patterns of soil loss and source apportionment between rill and interrill erosion.展开更多
The rapid advancement of machine learning(ML)technology across diverse domains has provided a framework for discovering and rationalising materials and photovoltaic devices.This study introduces a five-step methodolog...The rapid advancement of machine learning(ML)technology across diverse domains has provided a framework for discovering and rationalising materials and photovoltaic devices.This study introduces a five-step methodology for implementing ML models in fabricating hole transport layer(HTL)free carbon-based PSCs(C-PSC).Our approach leverages various prevalentMLmodels,andwe curated a comprehensive dataset of 700 data points using SCAPS-1D simulation,encompassing variations in the thickness of the electron transport layer(ETL)and perovskite layers,along with bandgap characteristics.Our results indicate that the ANN-based ML model exhibits superior predictive accuracy for C-PSC device parameters,achieving a low root mean square error(RMSE)of 0.028 and a high R-squared value of 0.954.The novelty of this work lies in its systematic use ofMLto streamline the optimisation process,reducing the reliance on traditional trial-and-error methods and providing a deeper understanding of the interdependence of key device parameters.展开更多
In addition to sperm,some accessory substances transferred to females during copulation act as nuptial gifts by passing on valuable nutrients in many insect species.The nutritional status of the males can thus have a ...In addition to sperm,some accessory substances transferred to females during copulation act as nuptial gifts by passing on valuable nutrients in many insect species.The nutritional status of the males can thus have a great effect on the mating behavior,fecundity and even the longevity of females.However,little is known about the effect of male nutritional status on the female reproductive traits in migratory insect species,particularly when females experience nutrient shortage and have to choose between reproduction and migration.Here,Cnaphalocrocis medinalis,a migratory rice pest in Asia,was studied to explore this issue.Our results showed that in male moths fed with honey solution,their gonads had higher energy content than gonads of starved males,resulting in increased energy content of the bursa copulatrix of females after mating with fed males.Such females showed increased mating frequency,fecundity and longevity compared to females mating with starved males,indicating that male moths deliver nuptial gifts to females and improve their reproductive performance.However,when females were starved,only about 45%mated,with just a single copulation,regardless of male nutritional status.Starved females showed lower fecundity,and a longer pre-oviposition period(indicating a greater propensity to migrate),compared to fed females.However,copulation still significantly extended their longevity.These results suggest that starved females invest in migration to escape deteriorating habitats,rather than investing the nuptial gift to increased fecundity.Our results further our understanding of the reproductive adaptability of migratory insects under conditions of food stress.展开更多
The problem of repeated immersion-induced fatigue damage in engineering coal measures sedimentary rock,including coal-rock pillars,reservoir bank slopes,and water-rich tunnels at the boundary of coal mine underground ...The problem of repeated immersion-induced fatigue damage in engineering coal measures sedimentary rock,including coal-rock pillars,reservoir bank slopes,and water-rich tunnels at the boundary of coal mine underground reservoirs,has profound implications for their stability,safety,and operation,and can even lead to geological disasters.To address this issue,this paper aims to construct a constitutive model that accurately captures the comprehensive process of deformation and failure in water-bearing coal measures sedimentary rock.It explores the deformation characteristics of these formations and provides a theoretical foundation for numerical simulations of geological disasters induced by water-rock interaction.This study integrates the deformation mechanisms of void and matrix deformation in coal seam sedimentary rocks,while considering the influence of immersion cycles.Subsequently,it formulates a segmented constitutive model to depict the entire process of deformation and failure in cyclically immersed water-bearing coal measures sedimentary rock under uniaxial compression.The proposed model's accuracy and rationality are validated through comparisons with experimental research findings and existing theoretical curves from similar models.The results demonstrate the model's effectiveness in describing the deformation behavior of non-dense water-bearing coal measures sedimentary rock under uniaxial compression or low confining pressure before reaching peak stress,although further refinements may be necessary to precisely capture post-peak deformation characteristics.Model parameters,including the deformation caused by voids(γ0)between voids,increase exponentially with immersion times,while the elastic modulus(Ev)of voids and the parameter(F0)related to the average strength of microelements decrease exponentially.The homogeneity degree(m)exhibits no discernible pattern.These research outcomes provide valuable insights for the stability control of engineering coal measures sedimentary rock under water-rock interaction and the mitigation of related geological disasters.展开更多
基金financially supported by the Ministry of Science and Technology of China(Grant No.2018YFA0702100)the National Natural Science Foundation of China(Grant Nos.11874169,51972129)+3 种基金the National Key R&D Program of China(Grant No.2017YFE0120500)the Key Research and Development Program of Hubei(Grant No.2020BAB079)the South Xinjiang Innovation and Development Program of Key Industries of Xinjiang Production and Construction Corps(Grants No.2020DB002)the Hubei‘‘Chu-Tian Young Scholar”program.
文摘Clean energy and a sustainable environment are grand challenges that the world is facing which can be addressed by converting solar energy into transportable and storable fuels(chemical fuel).The main scientific and technological challenges for efficient solar energy conversion,energy storage,and environmental applications are the stability,durability,and performance of low-cost functional materials.Among different nanomaterials,perovskite type LaFeO_(3)has been extensively investigated as a photocatalyst due to its abundance,high stability,compositional and structural fexibility,high electrocatalytic activity,efficient sunlight absorption,and tunable band gap and band edges.Hence,it is urgent to write a comprehensive review to highlight the trend,challenges,and prospects of LaFeO_(3)in the field of photocatalytic solar energy conversion and environment purification.This critical review summarizes the history and basic principles of photocatalysis.Further,it reviews in detail the LaFeO_(3),applications,shortcomings,and activity enhancement strategies including the design of nanostructures,elemental doping,and heterojunctions construction such as Type-I,Type-II,Z-Type,and uncommon heterojunctions.Besides,the optical and electronic properties,charge carriers separation,electron transport phenomenon and alignment of the band gaps in LaFeO_(3)-based heterostructures are comprehensively discussed.
基金the National Natural Science Foundation of China (Nos. 11874169, 11574106, 61771448, and 51635007)the Double first-class research funding of China-EU Institute for Clean and Renewable Energy (ICARE-RP-2018-SOLAR-003)+1 种基金the Engineering and Physical Science Research Council, UK (EPSRC grant No EP/ P510956/1 and EP/R512801/1the China Postdoctoral Science Foundation under Grant No. 2017M622404
文摘A typical Z-scheme system is composed of two photocatalysts which generate two sets of charge carriers and split water into H2 and O2 at different locations.Scientists are struggling to enhance the efficiencies of these systems by maximizing their light absorption,engineering more stable redox couples,and discovering new O2 and H2 evolutions co-catalysts.In this work,Au decorated WO3/g-C3N4 Z-scheme nanocomposites are fabricated via wet-chemical and photo-deposition methods.The nanocomposites are utilized in photocatalysis for H2 production and 2,4-dichlorophenol(2,4-DCP)degradation.It is investigated that the optimized 4Au/6%WO3/CN nanocomposite is highly efficient for production of 69.9 and 307.3μmol h−1 g−1 H2 gas,respectively,under visible-light(λ>420 nm)and UV–visible illumination.Further,the fabricated 4Au/6%WO3/CN nanocomposite is significant(i.e.,100%degradation in 2 h)for 2,4-DCP degradation under visible light and highly stable in photocatalysis.A significant 4.17%quantum efficiency is recorded for H2 production at wavelength 420 nm.This enhanced performance is attributed to the improved charge separation and the surface plasmon resonance effect of Au nanoparticles.Solid-state density functional theory simulations are performed to countercheck and validate our experimental data.Positive surface formation energy,high charge transfer,and strong non-bonding interaction via electrostatic forces confirm the stability of 4Au/6%WO3/CN interface.
基金Counting at GTL funded by the Shenzhen Zhilan FoundationAlashan SEE Ecological Association+1 种基金Beijing Xianfeng FoundationCounting at PXL was funded by the Alashan SEE Chongqing Center
文摘Soaring bird migration often relies on suitable terrain and airflow;therefore,route selection is vital for successful migration.While age and experience have been identified as key factor influencing migration route selection among soaring raptors in the African-Eurasian Flyway,how they shape the migration route of soaring raptors in East Asia is still largely unknown.In this study,we investigated potential variations in the routes and timing in autumn migration of juvenile and older soaring birds,using count data of Greater Spotted Eagles(Clanga clanga)from two coastal sites and two inland sites in China.From 2020 to 2023,we recorded a total of 340 individuals,with the highest site averaging over 90 individuals per autumn,making it one of the world’s top single-season counts and thus a globally important site for this species.We found that 82% and 61% records from coastal sites were juveniles,significantly higher than inland sites(15% and 24%).Juveniles at all four sites exhibited markedly earlier median passage time than non-juveniles,with brief overlapping in their main migration periods.Both coastal sites are located on the tip of peninsulas stretching southwest,requiring long overwater flights if crossing the Bohai Bay or Beibu Gulf,which would be energetically demanding and increase mortality risk.Experienced individuals may have learned to avoid such terrain and subsequent detour,while juveniles are more prone to enter these peninsulas due to lack of experience and opportunities for social learning,or following other raptor species that are more capable of powered flight.Our findings highlight the importance of age and experience in migration route selection of large soaring birds.
基金financially supported by the Ministry of Science and Technology of China (Grant No. 2018YFA0702100)the National Natural Science Foundation of China (Grant No. 11874169,51972129)+4 种基金the National Key R&D Program of China (Grant No. 2017YFE0120500)the Key Research and Development Program of Hubei (Grant No. 2020BAB079)the South Xinjiang Innovation and Development Program of Key Industries of Xinjiang Production and Construction Corps (Grants No. 2020DB002)Engineering and Physical Sciences Research Council (EP/T025875/1)the Hubei “ChuTian Young Scholar” program。
文摘The photocatalytic performance of g-C_(3)N_(4) for CO_(2) conversion is still inadequate by several shortfalls including the instability,insu cient solar light absorption and rapid charge carrier's recombination rate. To solve these problems,herein,noble metals(Pt and Au)decorated Sr-incorporated g-C_(3)N_(4) photocatalysts are fabricated via the simple calcination and photo-deposition methods. The Sr-incorporation remarkably reduced the g-C_(3)N_(4) band gap from 2.7 to 2.54 eV,as evidenced by the UV–visible absorption spectra and the density functional theory results. The CO_(2) conversion performance of the catalysts was evaluated under visible light irradiation. The Pt/0.15 Sr-CN sample produced 48.55 and 74.54 μmol h-1 g-1 of CH_(4) and CO,respectively.These amounts are far greater than that produced by the Au/0.15 Sr-CN,0.15 Sr-CN,and CN samples. A high quantum e ciency of 2.92% is predicted for the Pt/0.15 Sr-CN sample. Further,the stability of the photocatalyst is confirmed via the photocatalytic recyclable test. The improved CO_(2) conversion performance of the catalyst is accredited to the promoted light absorption and remarkably enhanced charge separation via the Sr-incorporated mid gap states and the localized surface plasmon resonance e ect induced by noble metal nanoparticles.This work will provide a new approach for promoting the catalytic e ciency of g-C_(3)N_(4) for e cient solar fuel production.
基金supported by the National Natural Science Foundation of China(Nos.31971460 and 32271646s).
文摘Global climate changes have significantly affected tree growth and forest structures and functions in some arid and semi-arid regions,which are becoming warmer and wetter.Due to natural factors such as climate and terrain,some tree species may form different forest patches at the edges of their distribution areas.However,how forest patches of various sizes respond to climate change is unclear.In this study,we collected 203 tree cores from six different sizes of forest patches at the edge of the distribution area of Picea crassifolia Kom.in the northeast Tibetan Plateau.And we used the dendrochronology method to study the response of tree growth and resilience in different forest patches to climate change from 1961 to 2020.We simultaneously measured the contents of nonstructural carbohydrates(NSC),total nitrogen and total phosphorus of tree needles.Our results showed that the growth of trees in small-and medium-size forest patches(0.8–18.6 ha)has increased significantly.The early growing season(May–July)minimum temperature was the most important climate factor driving the growth of small-and medium-sized patch trees.The early growing season maximum temperature was the most important climate factor that inhibited the growth of trees in the largest patches(362.8 ha).The growth of individual trees in medium forest patches was better and the correlation with annual minimum temperature,maximum temperature,precipitation,actual evapotranspiration,and palmer drought severity index was stronger.The higher NSC content,stronger photosynthesis,and higher nitrogen utilization efficiency in leaves might be one of the reasons for the better growth of trees in moderate forest patches.In extreme drought years,as the forest patch area increased,the overall trend of tree growth resistance showed a unimodal pattern,with the highest at a forest patch area of 7.1 ha,while the overall trend of tree growth recovery was opposite.Therefore,we should strengthen the management of trees in large forest patches to cope with climate change.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.41502108,42372206&41602123)the China Postdoctoral Science Foundation(Grant No.2016T90667)+1 种基金the China Scholarship Council Project(Grant No.201907770004)the Fundamental Research Funds for the Universities of Henan Province(Grant No.NSFRF220401).
文摘Lake-level changes can significantly affect paleoenvironmental evolution,resource occurrence,terrestrial carbon budget,and biodiversity in continental basins.Climate is one of the most critical factors controlling lake-level changes.Paleoclimate of the Early Jurassic has been evidenced by oscillating icehouses to(super)greenhouses with interrupted intermittent extreme climatic events(hyperthermal and cooling),e.g.,the Toarcian oceanic anoxic event(~183 Ma)and the late Pliensbachian cooling event(~185 Ma).Lake-level evolution and hydrologic cycling on Earth’s surface during the Early Jurassic icehouses-to-(super)greenhouses are thus far poorly understood due to a lack of continuous high-resolution nonmarine evidence.Here we present a super-long nonmarine lake level record for this pivotal interval from the early Pliensbachian to Toarcian by sedimentary noise modeling,and construct a 16.7-Myr-long astronomical time scale(174.2 Ma to 190.9 Ma)based on cyclostratigraphy analysis of rock color datasets(CIE b*)of the Qaidam Basin.Our results document lake-level oscillations on a 5-to 10-million-year(Myr)scale which shows a pronounced correlation with long-term climate variation and extreme climatic events,and 1-to 2.5-Myr-scale lake-level changes that are prominently paced by the 2.4-Myr long-eccentricity forcing and the 1.2-Myr obliquity forcing.At the Pliensbachian Stage,the 1.2-Myr-scale lake-level changes are in phase with the coeval sealevel variations.Orbitally forced growth and decay of the ephemeral or permanent ice sheets in polar regions are interpreted to control the synchronous ups-and-downs of continental lake level and global sea level.However,during the Toarcian ice-free greenhouses to(super)greenhouses,the 1.2-Myr-scale lake-level variations show an anti-phase relationship with global sea level,indicating a‘seesaw’interaction between continental reservoirs(lakes and groundwater)and global oceans.The 2.4-Myr longeccentricity cycles mainly regulate variations of lake level and sea level by controlling the growth and decay of small-scale continental ice sheets,which is especially notable during the Pliensbachian Stage.These findings indicate a remarkable transition of hydrological cycling pattern during the Pliensbachian-Toarcian icehouses to(super)greenhouses,which provides new perspectives and evidence for investigating the hypothesis of global sea-level changes(e.g.,glacio-eustasy and aquifer-eustasy)and long-period astronomical forcing in nonmarine stratigraphy.
基金supported by the National Natural Science Foundation of China(Grant No.51976126)the Natural Science Foundation of Shanghai(Grant Nos.22ZR1442700,22WZ2503100,and 20ZR1438600)Shanghai Municipal Science and Technology Committee of Shanghai Outstanding Academic Leaders Plan(Grant No.21XD1402400)。
文摘Phase change materials(PCMs)have remarkable energy storage capacity and promising applications in the field of thermal control of electronic products.The problem of thermal property improvement and heat transfer of PCMs in metal-foam heatsinks is an important task for thermal management of electronic components.Mixed paraffin samples were prepared by mixing appropriate proportions of paraffin(mass)at various temperatures.Differential scanning calorimetry analysis revealed that the maximum enthalpy of 206.3 J/g is obtained by mixing 20%of 17°C liquid paraffin and 80%of 29℃ solid paraffin.Heating and cooling cycling tests revealed that mixed paraffin exhibits excellent thermal stability and that the regulation method marginally affects thermal stability.Moreover,composites were prepared by embedding PCM into a copper foam by melt impregnation.The thermal conductivity of the composites increased to 4.35 W/(m K),corresponding to 20 times its original value.In addition,density functional theory and experimental results were in good agreement,indicating that the regulation method is practical and effective.
文摘The silver Y moth Autographa gamma undertakes windbome spring and fall migrations between winter breeding re- gions around the Mediterranean and summer breeding regions in northern Europe. Flight behaviors facilitating these migrations include: (i) selection of seasonally-favorable tailwinds; (ii) flying at the altitude of the fastest winds; (iii) adopting flight headings that partially counteract crosswind drift; and (iv) seasonal reversal of preferred directions between spring and fall. In the UK, ra- dar measurements indicate that migratory activity is pronounced during the spring and fall, but is usually very low during mid- summer (July). However, an atypically intense period of high-altitude flight was recorded during July 2006, and in this study we compare the flight behavior of A. gamma during these midsummer movements with the more typical spring and fall migrations. During July 2006, activity was most intense at significantly lower altitudes than occurred in spring or fall, and was not associated with the height of the fastest winds; consequently displacement speeds were significantly slower. The most striking difference was an absence of tailwind selectivity in July with windborne movements occurring on almost every night of the month and on tailwinds from all directions. Finally, orientation behavior was quantitatively different during July, with significantly greater dis- persion of flight headings and displacements than observed in spring and fall. We discuss mechanisms which could have caused these differences, and conclude that a lack of appropriate photopcriod cues during development of the summer generation resulted in randomly-oriented 'dispersive' movements that were strikingly different from typical seasonal migrations .
文摘Accurately quantifying rates of soil erosion requires capturing both the volumetric nature of the visible,convergent fluvial pathways(also known as rills)and the subtle nature of the less-visible,diffuse pathways(interrill areas).The aim of this study was to use Rare Earth Oxide(REO)tracers and Structure-from-Motion(SfM)photogrammetry to elucidate retrospective information about soil erosion rates and sediment sources during different soil erosion conditions,within a controlled laboratory environment.The experimental conditions created erosion events consistent with diffuse and convergent erosion processes.REO tracers allowed the sediment transport distances of over 2 m to be described,and helped resolved the relative contribution of diffuse and convergent soil erosion;interrill areas were also iden-tified as a significant sediment sources soil loss under convergent erosion conditions.While the potential for SfM photogrammetry to resolve sub-millimetre elevations changes was demonstrated,under some conditions non-erosional changes in surface elevation,such as compaction,exceeded volumes of soil loss via diffuse erosion.The discrepancies between SfM Photogrammetry calculations and REO tagged sediment export were beneficial,identifying that during soil erosion events sediment in both aggregate and particle form is deposited within the convergent features,even when the rill extended the full length of the soil surface.The combination of SfM photogrammetry and REO tracers has provided a novel platform for building a spatial understanding of patterns of soil loss and source apportionment between rill and interrill erosion.
基金funded by the Engineering and Physical Sciences Research Council,UK:PhD Fellowship and Engineering and Physical Sciences Research Council,UK:EP/T025875/1.
文摘The rapid advancement of machine learning(ML)technology across diverse domains has provided a framework for discovering and rationalising materials and photovoltaic devices.This study introduces a five-step methodology for implementing ML models in fabricating hole transport layer(HTL)free carbon-based PSCs(C-PSC).Our approach leverages various prevalentMLmodels,andwe curated a comprehensive dataset of 700 data points using SCAPS-1D simulation,encompassing variations in the thickness of the electron transport layer(ETL)and perovskite layers,along with bandgap characteristics.Our results indicate that the ANN-based ML model exhibits superior predictive accuracy for C-PSC device parameters,achieving a low root mean square error(RMSE)of 0.028 and a high R-squared value of 0.954.The novelty of this work lies in its systematic use ofMLto streamline the optimisation process,reducing the reliance on traditional trial-and-error methods and providing a deeper understanding of the interdependence of key device parameters.
基金supported by the National Key Research and Development Program of China(2016YFD0300702)the Fundamental Research Funds for the Central Universities(China)(KJYQ201902,KJJQ201803).
文摘In addition to sperm,some accessory substances transferred to females during copulation act as nuptial gifts by passing on valuable nutrients in many insect species.The nutritional status of the males can thus have a great effect on the mating behavior,fecundity and even the longevity of females.However,little is known about the effect of male nutritional status on the female reproductive traits in migratory insect species,particularly when females experience nutrient shortage and have to choose between reproduction and migration.Here,Cnaphalocrocis medinalis,a migratory rice pest in Asia,was studied to explore this issue.Our results showed that in male moths fed with honey solution,their gonads had higher energy content than gonads of starved males,resulting in increased energy content of the bursa copulatrix of females after mating with fed males.Such females showed increased mating frequency,fecundity and longevity compared to females mating with starved males,indicating that male moths deliver nuptial gifts to females and improve their reproductive performance.However,when females were starved,only about 45%mated,with just a single copulation,regardless of male nutritional status.Starved females showed lower fecundity,and a longer pre-oviposition period(indicating a greater propensity to migrate),compared to fed females.However,copulation still significantly extended their longevity.These results suggest that starved females invest in migration to escape deteriorating habitats,rather than investing the nuptial gift to increased fecundity.Our results further our understanding of the reproductive adaptability of migratory insects under conditions of food stress.
基金financially supported by National Natural Science Foundation of China(51874283)Youth Fund of the National Natural Science Foundation of China(52304133)Department of Science and Technology of Liaoning province(2023-BS-083).
文摘The problem of repeated immersion-induced fatigue damage in engineering coal measures sedimentary rock,including coal-rock pillars,reservoir bank slopes,and water-rich tunnels at the boundary of coal mine underground reservoirs,has profound implications for their stability,safety,and operation,and can even lead to geological disasters.To address this issue,this paper aims to construct a constitutive model that accurately captures the comprehensive process of deformation and failure in water-bearing coal measures sedimentary rock.It explores the deformation characteristics of these formations and provides a theoretical foundation for numerical simulations of geological disasters induced by water-rock interaction.This study integrates the deformation mechanisms of void and matrix deformation in coal seam sedimentary rocks,while considering the influence of immersion cycles.Subsequently,it formulates a segmented constitutive model to depict the entire process of deformation and failure in cyclically immersed water-bearing coal measures sedimentary rock under uniaxial compression.The proposed model's accuracy and rationality are validated through comparisons with experimental research findings and existing theoretical curves from similar models.The results demonstrate the model's effectiveness in describing the deformation behavior of non-dense water-bearing coal measures sedimentary rock under uniaxial compression or low confining pressure before reaching peak stress,although further refinements may be necessary to precisely capture post-peak deformation characteristics.Model parameters,including the deformation caused by voids(γ0)between voids,increase exponentially with immersion times,while the elastic modulus(Ev)of voids and the parameter(F0)related to the average strength of microelements decrease exponentially.The homogeneity degree(m)exhibits no discernible pattern.These research outcomes provide valuable insights for the stability control of engineering coal measures sedimentary rock under water-rock interaction and the mitigation of related geological disasters.