Excessive concentrations of toxic metals are a global threat to aquatic systems.Taking a typical tributary(Zijiang River,ZR)of the midstream of the Yangtze River as the research area,the concentration distribution and...Excessive concentrations of toxic metals are a global threat to aquatic systems.Taking a typical tributary(Zijiang River,ZR)of the midstream of the Yangtze River as the research area,the concentration distribution and chemical fractions occurrence characteristics of five toxic metals(Cd,Cr,Cu,Pb,and Zn)were analyzed,their potential sources were explored,and their contamination and ecological risk was assessed.In the surface waters and sediments,there were high concentrations of Zn,a low concentration of Cd,and small spatial differences in concentration among the upstream,midstream,and downstream.In terms of speciation,Cd mainly existed in the acid-soluble fraction,Pb mainly existed in the reducible fraction,and Cr,Cu,and Zn mainly existed in the residue fraction.The potential sources in surface waters and sediments were determined to be industrial emissions and agricultural non-point sources through the absolute principal component scores–multiple linear regression model(APCS–MLR).Based on the assessment results of total concentration and speciation,Cd was the typical contamination element in ZR sediments.In addition,the secondary phase enrichment factor(SPEF)based on speciation underestimates the degree of Pb contamination,and the ecological risk of Zn assessed by the ratio of secondary phase and primary phase(RSP)and the risk assessment code(RAC)was higher than that of Cr,which was inconsistent with the results based on total concentrations.SOM and Al/Fe/Mn cycles in sediments influenced the geochemical behavior of toxic metals.展开更多
In this study,different types of small molecular carbon sources such as melamine,dicyandiamine,pyrocatechol,and o-phenylenediamine were used to regulate the surface structures of iron/nitrogen/carbonbased composites(F...In this study,different types of small molecular carbon sources such as melamine,dicyandiamine,pyrocatechol,and o-phenylenediamine were used to regulate the surface structures of iron/nitrogen/carbonbased composites(Fe-N/C),which were used to activate peroxymonosulfate(PMS).The relationship between different small molecular carbon sources and the electronic structure was investigated.The characteristics of metal-carrier interaction in the Fe-N/C were clarified.As a result,there were significant differences in the degradation efficiency of catalysts prepared with different small molecular carbon sources,which was related to the types of active sites.Density functional theory(DFT)and experiments results showed that the catalyst rich in C-O-C and FeN_(x)exhibited better catalytic activity,which may be attributed to the higher adsorption energy for PMS.The main active species for catalytic degradation of ofloxacin were identified as sulfate radical(SO_(4)^(·-))and hydroxyl radical(^(·)OH)by electron paramagnetic resonance(EPR)spectra.The introduction of different small molecular carbon sources can significantly affect the distribution and electronic structure of active sites on the catalyst surface,thereby regulating the generation and migration of radicals.展开更多
Collagen is a class of mammalian extracellular matrix of the main structural proteins,widely present in the skin,bone,muscle and other tissues and it plays a role in supporting,repairing,and protecting tissue cells.Na...Collagen is a class of mammalian extracellular matrix of the main structural proteins,widely present in the skin,bone,muscle and other tissues and it plays a role in supporting,repairing,and protecting tissue cells.Natural source extraction and artificial synthesis provide a rich source of collagen.As a macromolecular material,collagen has good application potential in cosmetics,pharmaceutical,medical and food industries.Collagen has generated a great deal of interest in the cosmetic industry due to its abundance,strength,and direct correlation with skin aging.Collagen is widely used in cosmetics due to its unique structure,good biocompatibility and low antigenicity,as well as rich biological functions.To enhance the youthfulness and health of the user,the cosmetic industry adds collagen to products such as eye creams,face creams,and nutritional supplements,and uses it in medical aesthetic techniques such as tissue fillers,skin replacement,and soft skin enhancement.This paper mainly reviews the sources and types of collagen used in cosmetics industry,then introduces the effects of collagen in cosmetics and prospects the development prospects of collagen in dermatologic and cosmetic fields.展开更多
Heavy metal(loid)(HM)pollution in agricultural soils has become an environmental concern in antimony(Sb)mining areas.However,priority pollution sources identification and deep understanding of environmental risks of H...Heavy metal(loid)(HM)pollution in agricultural soils has become an environmental concern in antimony(Sb)mining areas.However,priority pollution sources identification and deep understanding of environmental risks of HMs face great challenges due to multiple and complex pollution sources coexist.Herein,an integrated approach was conducted to distinguish pollution sources and assess human health risk(HHR)and ecological risk(ER)in a typical Sb mining watershed in Southern China.This approach combines absolute principal component score-multiple linear regression(APCS-MLR)and positivematrix factorization(PMF)models with ER and HHR assessments.Four pollution sources were distinguished for both models,and APCS-MLR model was more accurate and plausible.Predominant HM concentration source was natural source(39.1%),followed by industrial and agricultural activities(23.0%),unknown sources(21.5%)and Sb mining and smelting activities(16.4%).Although natural source contributed the most to HM concentrations,it did not pose a significant ER.Industrial and agricultural activities predominantly contributed to ER,and attention should be paid to Cd and Sb.Sb mining and smelting activities were primary anthropogenic sources of HHR,particularly Sb and As contaminations.Considering ER and HHR assessments,Sb mining and smelting,and industrial and agricultural activities are critical sources,causing serious ecological and health threats.This study showed the advantages of multiple receptor model application in obtaining reliable source identification and providing better source-oriented risk assessments.HM pollution management,such as regulating mining and smelting and implementing soil remediation in polluted agricultural soils,is strongly recommended for protecting ecosystems and humans.展开更多
With the development of integrated power and gas distribution systems(IPGS)incorporating renewable energy sources(RESs),coordinating the restoration processes of the power distribution system(PS)and the gas distributi...With the development of integrated power and gas distribution systems(IPGS)incorporating renewable energy sources(RESs),coordinating the restoration processes of the power distribution system(PS)and the gas distribution system(GS)by utilizing the benefits of RESs enhances service restoration.In this context,this paper proposes a coordinated service restoration framework that considers the uncertainty in RESs and the bi-directional restoration interactions between the PS and GS.Additionally,a coordinated service restoration model is developed considering the two systems’interdependency and the GS’s dynamic characteristics.The objective is to maximize the system resilience index while adhering to operational,dynamic,restoration logic,and interdependency constraints.A method for managing uncertainties in RES output is employed,and convexification techniques are applied to address the nonlinear constraints arising from the physical laws of the IPGS,thereby reducing solution complexity.As a result,the service restoration optimization problem of the IPGS can be formulated as a computationally tractable mixed-integer second-order cone programming problem.The effectiveness and superiority of the proposed framework are demonstrated through numerical simulations conducted on the interdependent IEEE 13-bus PS and 9-node GS.The comparative results show that the proposed framework improves the system resilience index by at least 65.07%compared to traditional methods.展开更多
Traditional beamforming techniques may not accurately locate sources in scenarios with both stationary and rotating sound sources.The existence of rotating sound sources can cause blurring in the stationary beamformin...Traditional beamforming techniques may not accurately locate sources in scenarios with both stationary and rotating sound sources.The existence of rotating sound sources can cause blurring in the stationary beamforming map.Current algorithms for separating different moving sound sources have limited effectiveness,leading to significant residual noise,especially when the rotating source is strong enough to mask stationary sources completely.To overcome these challenges,a novel solution utilizing a virtual rotating array in the modal domain combined with robust principal component analysis is proposed to separate sound sources with different rotational speeds.This approach,named Robust Principal Component Analysis in the Modal domain(RPCA-M),investigates the performance of convex nuclear norm and non-convex Schatten-p norm to distinguish stationary and rotating sources.By comparing the errors in Cross-Spectral Matrix(CSM)recovery and acoustic imaging across different algorithms,the effectiveness of RPCA-M in separating stationary and moving sound sources is demonstrated.Importantly,this method effectively separates sound sources,even when there are significant variations in their amplitudes at different rotation speeds.展开更多
Precipitation isotopes(δ^(18)O and δ^(2)H)are closely related to meteorological conditions for precipitation generation and the initial state of water vapor source areas,and are essential to the study of the regiona...Precipitation isotopes(δ^(18)O and δ^(2)H)are closely related to meteorological conditions for precipitation generation and the initial state of water vapor source areas,and are essential to the study of the regional hydrological cycle.The deuterium excess(d-excess)indicates deviation in isotope fractionation during evaporation and can trace water vapor sources.This study analyzed 443 precipitation samples collected from the Gannan Plateau,China in 2022 to assess precipitation isotope variations and their driving factors.Water vapor sources were evaluated using the Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT),Concentration Weighted Trajectory(CWT),and Potential Source Contribution Factor(PSCF)models.Results showed that precipitation isotope values showed significant spatial and temporal variations on the Gannan Plateau.Temporally,precipitation isotope values peaked in June(when evaporation dominated)and minimized in March(depletion effect of air masses in the westerly wind belt).Spatially,the isotope values showed a distribution pattern of"high in the east and low in the west",which was mainly regulated by the differences in altitude and local meteorological conditions.Compared with the global meteoric water line(GMWL)with equation of δ^(2)H=8.00δ^(18)O+10.00,the slope and intercept of local meteoric water line(LMWL)for precipitation on the Gannan Plateau were smaller(7.49 and 7.63,respectively),reflecting the existence of a stronger secondary evaporation effect under the clouds in the region.The sources of water vapor on the Gannan Plateau showed significant seasonality and spatial heterogeneity.Specifically,the westerly belt and monsoon were the main water vapor transport paths at each sampling point,with Central Asian continental water vapor dominating in spring(53.49%),Indian Ocean water vapor dominating in summer(52.53%),Atlantic Ocean water vapor dominating in autumn(46.74%),and Atlantic Ocean and Mediterranean Sea water vapor dominating in winter(42.30%and 33.68%,respectively).Changes in the intensity of convective activity and Outgoing Longwave Radiation(OLR)affected the enrichment of isotopic values,which exhibited the same change trends as δ^(18)O.During the precipitation process,the δ^(18)O value first decreased and then increased.During the initial and final stages of precipitation process,precipitation was mainly influenced by continental air masses,while during the middle stage,it was controlled by marine air masses.The systematic research on precipitation isotopes and water vapor sources is important for climate change research and extreme precipitation prediction on the Gannan Plateau and other similar areas.展开更多
Inhalation of atmospheric PM_(2.5)can induce the generation of excessive reactive oxygen species(ROS)in human alveoli,triggering local and systemic inflammation,which can directly or indirectly result in respiratory a...Inhalation of atmospheric PM_(2.5)can induce the generation of excessive reactive oxygen species(ROS)in human alveoli,triggering local and systemic inflammation,which can directly or indirectly result in respiratory and cardiovascular diseases.In this study,we assessed the oxidative potential(OP)of fresh and O_(3)-aged PM_(2.5)particles from various urban and rural emission sources using the dithiothreitol(DTT)method.Our results revealed variations in the OP of fresh PM_(2.5)among different emission sources,with biomass burning sources exhibiting the highest OP,followed by industrial areas,vehicular emissions,cooking emissions,and suburban areas,respectively.Water-soluble organics and transition metals might potentially exert significant influence on particle OP.O_(3)aging notably decreased the OP of PM_(2.5)particles,possibly due to the oxidation of highly DTT-active components into low redox-active small molecules.Moreover,the evolution of OP in different PM_(2.5)components,including methanol-soluble and insoluble fractions,exhibited distinct responses to O_(3)aging for source-oriented PM_(2.5).Additionally,differences in chemical composition between fresh and aged PM_(2.5)were further elucidated through measurements of component-dependent hygroscopic behaviors and phase transitions.This study systematically delineates variances in the toxic potential of fresh and O_(3)-aged PM_(2.5)from various anthropogenic sources.The findings highlight the intrinsic compositional dependence of particle OP and provide essential insights for assessing the health effects of source-oriented PM_(2.5),as well as for formulating human health protection policies.展开更多
Ultrafast electron sources, which enable high spatiotemporal resolution in time-resolved electron microscopy and scanning probe microscopy, are receiving increased attention. The most widely used method for achieving ...Ultrafast electron sources, which enable high spatiotemporal resolution in time-resolved electron microscopy and scanning probe microscopy, are receiving increased attention. The most widely used method for achieving ultrafast electron sources involves irradiating metal tips by ultrashort laser pulses, causing electron beam emission via the photoelectric effect [including photon-driven(quantum) or field-driven(classical) emission]. However, the thermionic electrons emission process due to the heating effect of ultrashort lasers, particularly its dynamic aspects, has rarely been addressed in previous studies. In this paper, we improved the signal-to-noise ratio of a two-pulse correlation measurement on the tip electron emission by nearly two orders of magnitude using a delay time modulation method. This allowed us to obtain information on the temperature evolution of hot electrons and phonons in a non-equilibrium state, and to extract characteristic time scales for electron-phonon and phonon-phonon scattering. Our findings indicate that the thermionic electrons emission, unlike the instantaneous photoelectric effect, causes electron emission to lag behind the laser pulse by tens of picoseconds, thus significantly affecting the detection of ultrafast dynamics of samples. Furthermore, such a lagging effect was found to be sensitive to the local structure of the metal tip, offering new insights into the improved design of ultrafast electron sources.展开更多
The presence of background classical sources affects quantum field theory significantly in different ways.Neutrino oscillation is a phenomenon that confirms that neutrinos are massive fermions in nature,a celebrated r...The presence of background classical sources affects quantum field theory significantly in different ways.Neutrino oscillation is a phenomenon that confirms that neutrinos are massive fermions in nature,a celebrated result in modern physics.Neutrino oscillation plays an important role in many astrophysical observations.However,the interactions between the background classical sources with neutrinos are not often considered.In the present article,we show the effect of some classical sources,namely matter currents,electromagnetic waves,torsion,and gravitational waves on neutrino oscillation.It is shown explicitly that the above sources can change the helicity state of neutrinos during neutrino oscillation.展开更多
Lead(Pb)plays a significant role in the nuclear industry and is extensively used in radiation shielding,radiation protection,neutron moderation,radiation measurements,and various other critical functions.Consequently,...Lead(Pb)plays a significant role in the nuclear industry and is extensively used in radiation shielding,radiation protection,neutron moderation,radiation measurements,and various other critical functions.Consequently,the measurement and evaluation of Pb nuclear data are highly regarded in nuclear scientific research,emphasizing its crucial role in the field.Using the time-of-flight(ToF)method,the neutron leakage spectra from three^(nat)Pb samples were measured at 60°and 120°based on the neutronics integral experimental facility at the China Institute of Atomic Energy(CIAE).The^(nat)Pb sample sizes were30 cm×30 cm×5 cm,30 cm×30 cm×10 cm,and 30 cm×30 cm×15 cm.Neutron sources were generated by the Cockcroft-Walton accelerator,producing approximately 14.5 MeV and 3.5 MeV neutrons through the T(d,n)^(4)He and D(d,n)^(3)He reactions,respectively.Leakage neutron spectra were also calculated by employing the Monte Carlo code of MCNP-4C,and the nuclear data of Pb isotopes from four libraries:CENDL-3.2,JEFF-3.3,JENDL-5,and ENDF/B-Ⅷ.0 were used individually.By comparing the simulation and experimental results,improvements and deficiencies in the evaluated nuclear data of the Pb isotopes were analyzed.Most of the calculated results were consistent with the experimental results;however,a few areas did not fit well.In the(n,el)energy range,the simulated results from CENDL-3.2 were significantly overestimated;in the(n,inl)D and the(n,inl)C energy regions,the results from CENDL-3.2 and ENDF/B-Ⅷ.0 were significantly overestimated at 120°,and the results from JENDL-5 and JEFF-3.3 are underestimated at 60°in the(n,inl)D energy region.The calculated spectra were analyzed by comparing them with the experimental spectra in terms of the neutron spectrum shape and C/E values.The results indicate that the theoretical simulations,using different data libraries,overestimated or underestimated the measured values in certain energy ranges.Secondary neutron energies and angular distributions in the data files have been presented to explain these discrepancies.展开更多
Microring resonators(MRRs)are extensively utilized in photonic chips for generating quantum light sources and enabling high-efficiency nonlinear frequency conversion.However,conventional microrings are typically optim...Microring resonators(MRRs)are extensively utilized in photonic chips for generating quantum light sources and enabling high-efficiency nonlinear frequency conversion.However,conventional microrings are typically optimized for a single specific function,limiting their versatility in multifunctional applications.In this work,we propose a reconfigurable microring resonator architecture designed to accommodate diverse application requirements.By integrating a cascaded Mach–Zehnder interferometer(MZI)as the microring coupler,the design enables independent control of the quality factors for pump,signal and idler photons through two tunable phase shifters.This capability allows for dynamic tuning and optimization of critical performance parameters,including photon-pair generation rate(PGR),spectral purity and single photon heralding efficiency(HE).The proposed structure is implemented on a silicon photonic chip,and experimental results exhibit a wide range of tunability for these parameters,with excellent agreement with theoretical predictions.This flexible and multi-functional design offers a promising pathway for high-performance,highly integrated on-chip quantum information processing systems.展开更多
VOCs(Volatile organic compounds)exert a vital role in ozone and secondary organic aerosol production,necessitating investigations into their concentration,chemical characteristics,and source apportionment for the effe...VOCs(Volatile organic compounds)exert a vital role in ozone and secondary organic aerosol production,necessitating investigations into their concentration,chemical characteristics,and source apportionment for the effective implementation of measures aimed at preventing and controlling atmospheric pollution.FromJuly to October 2020,onlinemonitoringwas conducted in the main urban area of Shijiazhuang to collect data on VOCs and analyze their concentrations and reactivity.Additionally,the PMF(positive matrix factorization)method was utilized to identify the VOCs sources.Results indicated that the TVOCs(total VOCs)concentration was(96.7±63.4μg/m^3),with alkanes exhibiting the highest concentration of(36.1±26.4μg/m^3),followed by OVOCs(16.4±14.4μg/m^3).The key active components were alkenes and aromatics,among which xylene,propylene,toluene,propionaldehyde,acetaldehyde,ethylene,and styrene played crucial roles as reactive species.The sources derived from PMF analysis encompassed vehicle emissions,solvent and coating sources,combustion sources,industrial emissions sources,as well as plant sources,the contribution of which were 37.80%,27.93%,16.57%,15.24%,and 2.46%,respectively.Hence,reducing vehicular exhaust emissions and encouraging neighboring industries to adopt low-volatile organic solvents and coatings should be prioritized to mitigate VOCs levels.展开更多
Nitrogen removal from domestic sewage is usually limited by insufficient carbon source and electron donor.An economical solid carbon source was developed by composition of polyvinyl alcohol,sodium alginate,and corncob...Nitrogen removal from domestic sewage is usually limited by insufficient carbon source and electron donor.An economical solid carbon source was developed by composition of polyvinyl alcohol,sodium alginate,and corncob,which was utilized as external carbon source in the anaerobic anoxic oxic(AAO)-biofilter for the treatment of low carbon-to-nitrogen ratio domestic sewage,and the nitrogen removal was remarkably improved from 63.2%to 96.5%.Furthermore,the effluent chemical oxygen demand maintained at 35 mg/L or even lower,and the total nitrogenwas reduced to less than 2mg/L.Metagenomic analysis demonstrated that the microbial communities responsible for potential denitrification and organic matter degradation in both AAO and the biofilter reactors were mainly composed of Proteobacteria and Bacteroides,respectively.The solid carbon source addition resulted in relatively high abundance of functional enzymes responsible for NO_(3)^(−)-N to NO_(2)^(−)-N con-version in both AAO and the biofilter reactors,thus enabled stable reaction.The carbon source addition during glycolysis primarily led to the increase of genes associated with the metabolic conversion of fructose 1.6P2 to glycerol-3P The reactor maintained high abun-dance of genes related to the tricarboxylic acid cycle,and then guaranteed efficient carbon metabolism.The results indicate that the composite carbon source is feasible for denitri-fication enhancement of AAO-biofilter,which contribute to the theoretical foundation for practical nitrogen removal application.展开更多
Lake Baiyangdian is one of China’s largest macrophyte-derived lakes,facing severe challenges related to water quality maintenance and eutrophication prevention.Dissolved organic matter(DOM)was a huge carbon pool and ...Lake Baiyangdian is one of China’s largest macrophyte-derived lakes,facing severe challenges related to water quality maintenance and eutrophication prevention.Dissolved organic matter(DOM)was a huge carbon pool and its abundance,property,and transformation played important roles in the biogeochemical cycle and energy flow in lake ecosystems.In this study,Lake Baiyangdian was divided into four distinct areas:Unartificial Area(UA),Village Area(VA),Tourism Area(TA),and Breeding Area(BA).We examined the diversity of DOM properties and sources across these functional areas.Our findings reveal that DOM in this lake is predominantly composed of protein-like substances,as determined by excitation-emission matrix and parallel factor analysis(EEM-PARAFAC).Notably,the exogenous tyrosine-like component C1 showed a stronger presence in VA and BA compared to UA and TA.Ultrahigh-resolution mass spectrometry(FT-ICR MS)unveiled a similar DOM molecular composition pattern across different functional areas due to the high relative abundances of lignan compounds,suggesting that macrophytes significantly influence the material structure of DOM.DOM properties exhibited specific associations with water quality indicators in various functional areas,as indicated by the Mantel test.The connections between DOM properties and NO_(3)-N andNH3-Nwere more pronounced in VA and BA than in UA and TA.Our results underscore the viability of using DOM as an indicator for more precise and scientific water quality management.展开更多
Water-soluble organic nitrogen(WSON)affects the formation,hygroscopicity,acidity of organic aerosols,and nitrogen biogeochemical cycles.However,qualitative and quantitative characterizations of WSON remain limited due...Water-soluble organic nitrogen(WSON)affects the formation,hygroscopicity,acidity of organic aerosols,and nitrogen biogeochemical cycles.However,qualitative and quantitative characterizations of WSON remain limited due to its chemical complexity.In the study,1-year field samples of particulate matter 2.5(PM_(2.5))were collected fromJune 2022 to May 2023 to analyze the WSON concentration in PM_(2.5),and correlation analysis,positive matrix factor(PMF),and potential source contribution function(PSCF)modelswere employed to elucidate WSON source apportionment and transport pathways.The results revealed that the mean WSON concentrations reached 1.98±2.64μg/m^(3) with a mean WSON to water-soluble total nitrogen(WSTN)ratio of 21%.Further,WSON concentration exhibited a seasonal variation trend,with higher values in winter and lower in summer.Five sources were identified as contributors to WSON in PM_(2.5) within the reservoir area through a comprehensive analysis including correlation analysis,PSCF and concentration weighted trajectory(CWT),and PMF analyses.These sources were agricultural,dust,combustion,traffic,and industrial sources,of which agricultural source emerged as the primary contributor(76.69%).The atmosphere in the reservoir area were primarily influenced by the transport of northeastern air masses,local agricultural activities,industrial cities along the trajectory,and coastal regions,exerting significant influences on the concentration of WSON in the reservoir area.The findings of this study addressed the research gap concerning organic nitrogen in PM_(2.5) within the reservoir area,thereby offering a theoretical foundation and data support in controlling nitrogen pollution in the Danjiangkou Reservoir area.展开更多
In this study,the occurrence,sources,and ecological risk of microplastics(>60μm)in the surface and bottom seawater were investigated in the Beibu Gulf,the northern South China Sea.The average abundance of micropla...In this study,the occurrence,sources,and ecological risk of microplastics(>60μm)in the surface and bottom seawater were investigated in the Beibu Gulf,the northern South China Sea.The average abundance of microplastics in surface and bottom waters was 1.35±0.93 and 0.79±0.50 items/m~3,respectively.Microplastics in both surface and bottom waters were predominantly in the form of fragments,and mostly in green.The composition of microplastics in surface water was primarily poly(methyl methacrylate)(PMA),whereas in bottom water,polyethylene(PE)dominated.Positive matrix factorization(PMF)modeling revealed that the primary sources of microplastics were pipeline abrasion,fishing activities,plastic waste,landfill disposal,transportation,aquaculture,and construction activities.The pollution load index(PLI)indicated that the overall risk of microplastic pollution in the Beibu Gulf was low.Conversely,the polymer hazard index(PHI)for microplastics was relatively high.These data underscore the importance of timely and effective reduction of human-intensive activities contributing to microplastic pollution and provide valuable information for further research in microplastic ecotoxicology and biogeochemistry.展开更多
Microwave digestion-inductively coupled plasma mass spectrometry(ICP-MS)was used to analyze the sources of lead in farmland soil and rice in the Jiulongjiang River Basin.The results suggested that the source of lead i...Microwave digestion-inductively coupled plasma mass spectrometry(ICP-MS)was used to analyze the sources of lead in farmland soil and rice in the Jiulongjiang River Basin.The results suggested that the source of lead in rice was differ from that in soil.There were four main sources of lead in farmland soil:natural source,agricultural source,industrial source and fossil fuel source,among which natural source,agricultural source and industrial source contributed more.There were four main sources of lead in rice:natural,agricultural,industrial and fossil fuel sources,and more importantly,fossil fuel sources.The comparison of lead isotope composition with potential sources(^(206)Pb/^(207)Pb,^(208)Pb/^(206)Pb,^(208)Pb/^(207)Pb)can provide a scientific basis for the identification and treatment of heavy metal lead pollution sources in farmland soil and rice in the Jiulong River Basin.展开更多
To explore the multicenter characteristics of endocrine-like phthalate esters(PAEs)in household dust and propose effective control strategies for global indoor public health.An on-site observational investigation was ...To explore the multicenter characteristics of endocrine-like phthalate esters(PAEs)in household dust and propose effective control strategies for global indoor public health.An on-site observational investigation was conducted in nine Chinese cities from 2018 to 2019.A total of 246 household dust sampleswere collected and analyzed for ten PAE congeners using Gas Chromatography-Mass Spectrometry(GC-MS).Questionnaires were used to gather information on building conditions,indoor behaviors,and ventilation habits.In residential dust from the nine cities,the total concentrations of the ten PAE congeners(PAEs)ranged from 0.921 to 29097.297μg/g.Dicyclohexyl phthalate(DCHP)and di(2-ethylhexyl)phthalate(DEHP)were the dominant congeners inPAEs.Childhood exposure to PAEs through dust ingestion was four orders of magnitude higher than through inhalation,with a carcinogenic risk of 5.47×10^(−6) for DEHP exposure in household dust.HigherPAEs concentrations were associated with higher temperature,double glazing,wall paint usage,television and computer use,and indoor plant growth.This multicenter on-site investigation confirmed PAE pollution characteristics and uncovered the inacceptable risk of daily DEHP exposure in household dust under real living conditions.Effective mitigation measures based on household-related information,residential characteristics,decoration materials,and lifestyle should be taken to build a healthy household environment.展开更多
This study investigates the surface effects on the operation of double-ended dislocation sources in single-crystal micropillars under compression.A comprehensive theoretical framework is formulated to derive the stres...This study investigates the surface effects on the operation of double-ended dislocation sources in single-crystal micropillars under compression.A comprehensive theoretical framework is formulated to derive the stress field of the source segment and the corresponding Peach-Koehler(PK)forces acting on this segment near the free surfaces.An analytical formulation is then developed to compare the source strength with and without the influence of the surface stress.The results reveal that the surface effects on the dislocation source strength are highly sensitive to the interplay between the source length and its distance from the free surface.These surface effects can either enhance or reduce the critical stress required for the source operation by up to 50%,leading to significant fluctuations in yield strength,as commonly observed in discrete dislocation dynamics simulations and experimental studies.These findings provide different interpretations for the size-dependent and stochastic yield stress behavior in face-centered cubic(FCC)micropillars.展开更多
基金supported by the National Natural Science Foundation of China(No.42030706).
文摘Excessive concentrations of toxic metals are a global threat to aquatic systems.Taking a typical tributary(Zijiang River,ZR)of the midstream of the Yangtze River as the research area,the concentration distribution and chemical fractions occurrence characteristics of five toxic metals(Cd,Cr,Cu,Pb,and Zn)were analyzed,their potential sources were explored,and their contamination and ecological risk was assessed.In the surface waters and sediments,there were high concentrations of Zn,a low concentration of Cd,and small spatial differences in concentration among the upstream,midstream,and downstream.In terms of speciation,Cd mainly existed in the acid-soluble fraction,Pb mainly existed in the reducible fraction,and Cr,Cu,and Zn mainly existed in the residue fraction.The potential sources in surface waters and sediments were determined to be industrial emissions and agricultural non-point sources through the absolute principal component scores–multiple linear regression model(APCS–MLR).Based on the assessment results of total concentration and speciation,Cd was the typical contamination element in ZR sediments.In addition,the secondary phase enrichment factor(SPEF)based on speciation underestimates the degree of Pb contamination,and the ecological risk of Zn assessed by the ratio of secondary phase and primary phase(RSP)and the risk assessment code(RAC)was higher than that of Cr,which was inconsistent with the results based on total concentrations.SOM and Al/Fe/Mn cycles in sediments influenced the geochemical behavior of toxic metals.
基金supported by National Natural Science Foundation of China(Nos.52170086,52300056)Natural Science Foundation of Shandong Province(Nos.ZR2021ME013,ZR202211280298)。
文摘In this study,different types of small molecular carbon sources such as melamine,dicyandiamine,pyrocatechol,and o-phenylenediamine were used to regulate the surface structures of iron/nitrogen/carbonbased composites(Fe-N/C),which were used to activate peroxymonosulfate(PMS).The relationship between different small molecular carbon sources and the electronic structure was investigated.The characteristics of metal-carrier interaction in the Fe-N/C were clarified.As a result,there were significant differences in the degradation efficiency of catalysts prepared with different small molecular carbon sources,which was related to the types of active sites.Density functional theory(DFT)and experiments results showed that the catalyst rich in C-O-C and FeN_(x)exhibited better catalytic activity,which may be attributed to the higher adsorption energy for PMS.The main active species for catalytic degradation of ofloxacin were identified as sulfate radical(SO_(4)^(·-))and hydroxyl radical(^(·)OH)by electron paramagnetic resonance(EPR)spectra.The introduction of different small molecular carbon sources can significantly affect the distribution and electronic structure of active sites on the catalyst surface,thereby regulating the generation and migration of radicals.
文摘Collagen is a class of mammalian extracellular matrix of the main structural proteins,widely present in the skin,bone,muscle and other tissues and it plays a role in supporting,repairing,and protecting tissue cells.Natural source extraction and artificial synthesis provide a rich source of collagen.As a macromolecular material,collagen has good application potential in cosmetics,pharmaceutical,medical and food industries.Collagen has generated a great deal of interest in the cosmetic industry due to its abundance,strength,and direct correlation with skin aging.Collagen is widely used in cosmetics due to its unique structure,good biocompatibility and low antigenicity,as well as rich biological functions.To enhance the youthfulness and health of the user,the cosmetic industry adds collagen to products such as eye creams,face creams,and nutritional supplements,and uses it in medical aesthetic techniques such as tissue fillers,skin replacement,and soft skin enhancement.This paper mainly reviews the sources and types of collagen used in cosmetics industry,then introduces the effects of collagen in cosmetics and prospects the development prospects of collagen in dermatologic and cosmetic fields.
基金supported by the National Natural Science Foundation of China(No.42107394)the Major Project of the National Natural Science Foundation of China(No.71991483)the Central Public-interest Scientific Institution Basal Research Fund(No.BSRF202309).
文摘Heavy metal(loid)(HM)pollution in agricultural soils has become an environmental concern in antimony(Sb)mining areas.However,priority pollution sources identification and deep understanding of environmental risks of HMs face great challenges due to multiple and complex pollution sources coexist.Herein,an integrated approach was conducted to distinguish pollution sources and assess human health risk(HHR)and ecological risk(ER)in a typical Sb mining watershed in Southern China.This approach combines absolute principal component score-multiple linear regression(APCS-MLR)and positivematrix factorization(PMF)models with ER and HHR assessments.Four pollution sources were distinguished for both models,and APCS-MLR model was more accurate and plausible.Predominant HM concentration source was natural source(39.1%),followed by industrial and agricultural activities(23.0%),unknown sources(21.5%)and Sb mining and smelting activities(16.4%).Although natural source contributed the most to HM concentrations,it did not pose a significant ER.Industrial and agricultural activities predominantly contributed to ER,and attention should be paid to Cd and Sb.Sb mining and smelting activities were primary anthropogenic sources of HHR,particularly Sb and As contaminations.Considering ER and HHR assessments,Sb mining and smelting,and industrial and agricultural activities are critical sources,causing serious ecological and health threats.This study showed the advantages of multiple receptor model application in obtaining reliable source identification and providing better source-oriented risk assessments.HM pollution management,such as regulating mining and smelting and implementing soil remediation in polluted agricultural soils,is strongly recommended for protecting ecosystems and humans.
基金funded by the Science and Technology Project of State Grid Shanxi Electric Power Company(5205E0230001).
文摘With the development of integrated power and gas distribution systems(IPGS)incorporating renewable energy sources(RESs),coordinating the restoration processes of the power distribution system(PS)and the gas distribution system(GS)by utilizing the benefits of RESs enhances service restoration.In this context,this paper proposes a coordinated service restoration framework that considers the uncertainty in RESs and the bi-directional restoration interactions between the PS and GS.Additionally,a coordinated service restoration model is developed considering the two systems’interdependency and the GS’s dynamic characteristics.The objective is to maximize the system resilience index while adhering to operational,dynamic,restoration logic,and interdependency constraints.A method for managing uncertainties in RES output is employed,and convexification techniques are applied to address the nonlinear constraints arising from the physical laws of the IPGS,thereby reducing solution complexity.As a result,the service restoration optimization problem of the IPGS can be formulated as a computationally tractable mixed-integer second-order cone programming problem.The effectiveness and superiority of the proposed framework are demonstrated through numerical simulations conducted on the interdependent IEEE 13-bus PS and 9-node GS.The comparative results show that the proposed framework improves the system resilience index by at least 65.07%compared to traditional methods.
基金supported by the National Key Research and Development Plan of China(No.2023YFB3406500)the National Natural Science Foundation of China(No.52475132)+2 种基金the Aeronautical Science Foundation of China(No.20200015053001)the Shaanxi Key Research Program Project,China(No.2024GX-ZDCYL-01–16)the Xi’an Key Industrial Chain Technology Research Project,China(No.2023JH-RGZNGG-0033)。
文摘Traditional beamforming techniques may not accurately locate sources in scenarios with both stationary and rotating sound sources.The existence of rotating sound sources can cause blurring in the stationary beamforming map.Current algorithms for separating different moving sound sources have limited effectiveness,leading to significant residual noise,especially when the rotating source is strong enough to mask stationary sources completely.To overcome these challenges,a novel solution utilizing a virtual rotating array in the modal domain combined with robust principal component analysis is proposed to separate sound sources with different rotational speeds.This approach,named Robust Principal Component Analysis in the Modal domain(RPCA-M),investigates the performance of convex nuclear norm and non-convex Schatten-p norm to distinguish stationary and rotating sources.By comparing the errors in Cross-Spectral Matrix(CSM)recovery and acoustic imaging across different algorithms,the effectiveness of RPCA-M in separating stationary and moving sound sources is demonstrated.Importantly,this method effectively separates sound sources,even when there are significant variations in their amplitudes at different rotation speeds.
基金supported by the National Natural Science Foundation of China(42161007)the Innovation Foundation of Higher Education Institutions of Gansu Province(2021B-081)the Foundation for Distinguished Young Scholars of Gansu Province(20JR10RA112).
文摘Precipitation isotopes(δ^(18)O and δ^(2)H)are closely related to meteorological conditions for precipitation generation and the initial state of water vapor source areas,and are essential to the study of the regional hydrological cycle.The deuterium excess(d-excess)indicates deviation in isotope fractionation during evaporation and can trace water vapor sources.This study analyzed 443 precipitation samples collected from the Gannan Plateau,China in 2022 to assess precipitation isotope variations and their driving factors.Water vapor sources were evaluated using the Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT),Concentration Weighted Trajectory(CWT),and Potential Source Contribution Factor(PSCF)models.Results showed that precipitation isotope values showed significant spatial and temporal variations on the Gannan Plateau.Temporally,precipitation isotope values peaked in June(when evaporation dominated)and minimized in March(depletion effect of air masses in the westerly wind belt).Spatially,the isotope values showed a distribution pattern of"high in the east and low in the west",which was mainly regulated by the differences in altitude and local meteorological conditions.Compared with the global meteoric water line(GMWL)with equation of δ^(2)H=8.00δ^(18)O+10.00,the slope and intercept of local meteoric water line(LMWL)for precipitation on the Gannan Plateau were smaller(7.49 and 7.63,respectively),reflecting the existence of a stronger secondary evaporation effect under the clouds in the region.The sources of water vapor on the Gannan Plateau showed significant seasonality and spatial heterogeneity.Specifically,the westerly belt and monsoon were the main water vapor transport paths at each sampling point,with Central Asian continental water vapor dominating in spring(53.49%),Indian Ocean water vapor dominating in summer(52.53%),Atlantic Ocean water vapor dominating in autumn(46.74%),and Atlantic Ocean and Mediterranean Sea water vapor dominating in winter(42.30%and 33.68%,respectively).Changes in the intensity of convective activity and Outgoing Longwave Radiation(OLR)affected the enrichment of isotopic values,which exhibited the same change trends as δ^(18)O.During the precipitation process,the δ^(18)O value first decreased and then increased.During the initial and final stages of precipitation process,precipitation was mainly influenced by continental air masses,while during the middle stage,it was controlled by marine air masses.The systematic research on precipitation isotopes and water vapor sources is important for climate change research and extreme precipitation prediction on the Gannan Plateau and other similar areas.
基金supported by the National Natural Science Foundation of China(No.42305109)Quzhou Municipal Science and Technology Bureau(No.2023K222).
文摘Inhalation of atmospheric PM_(2.5)can induce the generation of excessive reactive oxygen species(ROS)in human alveoli,triggering local and systemic inflammation,which can directly or indirectly result in respiratory and cardiovascular diseases.In this study,we assessed the oxidative potential(OP)of fresh and O_(3)-aged PM_(2.5)particles from various urban and rural emission sources using the dithiothreitol(DTT)method.Our results revealed variations in the OP of fresh PM_(2.5)among different emission sources,with biomass burning sources exhibiting the highest OP,followed by industrial areas,vehicular emissions,cooking emissions,and suburban areas,respectively.Water-soluble organics and transition metals might potentially exert significant influence on particle OP.O_(3)aging notably decreased the OP of PM_(2.5)particles,possibly due to the oxidation of highly DTT-active components into low redox-active small molecules.Moreover,the evolution of OP in different PM_(2.5)components,including methanol-soluble and insoluble fractions,exhibited distinct responses to O_(3)aging for source-oriented PM_(2.5).Additionally,differences in chemical composition between fresh and aged PM_(2.5)were further elucidated through measurements of component-dependent hygroscopic behaviors and phase transitions.This study systematically delineates variances in the toxic potential of fresh and O_(3)-aged PM_(2.5)from various anthropogenic sources.The findings highlight the intrinsic compositional dependence of particle OP and provide essential insights for assessing the health effects of source-oriented PM_(2.5),as well as for formulating human health protection policies.
基金supported by the National Key R&D Program under Grant No.2021YFA1400500the National Natural Science Foundation of China under Grant No.22273029+1 种基金the New Cornerstone Science Foundation through the New Cornerstone Investigator Program under Grant No.NCI202303 and the XPLORER PRIZEthe Beijing Outstanding Young Scientist Program under Grant No.JWZQ20240101002。
文摘Ultrafast electron sources, which enable high spatiotemporal resolution in time-resolved electron microscopy and scanning probe microscopy, are receiving increased attention. The most widely used method for achieving ultrafast electron sources involves irradiating metal tips by ultrashort laser pulses, causing electron beam emission via the photoelectric effect [including photon-driven(quantum) or field-driven(classical) emission]. However, the thermionic electrons emission process due to the heating effect of ultrashort lasers, particularly its dynamic aspects, has rarely been addressed in previous studies. In this paper, we improved the signal-to-noise ratio of a two-pulse correlation measurement on the tip electron emission by nearly two orders of magnitude using a delay time modulation method. This allowed us to obtain information on the temperature evolution of hot electrons and phonons in a non-equilibrium state, and to extract characteristic time scales for electron-phonon and phonon-phonon scattering. Our findings indicate that the thermionic electrons emission, unlike the instantaneous photoelectric effect, causes electron emission to lag behind the laser pulse by tens of picoseconds, thus significantly affecting the detection of ultrafast dynamics of samples. Furthermore, such a lagging effect was found to be sensitive to the local structure of the metal tip, offering new insights into the improved design of ultrafast electron sources.
基金supported by the SERB-Core Research Grant(Project RD/0122-SERB000-044)。
文摘The presence of background classical sources affects quantum field theory significantly in different ways.Neutrino oscillation is a phenomenon that confirms that neutrinos are massive fermions in nature,a celebrated result in modern physics.Neutrino oscillation plays an important role in many astrophysical observations.However,the interactions between the background classical sources with neutrinos are not often considered.In the present article,we show the effect of some classical sources,namely matter currents,electromagnetic waves,torsion,and gravitational waves on neutrino oscillation.It is shown explicitly that the above sources can change the helicity state of neutrinos during neutrino oscillation.
基金supported by the National Natural Science Foundation of China(Nos.11775311 and U2067205)the Stable Support Basic Research Program Grant(BJ010261223282)the Research and Development Project of China National Nuclear Corporation。
文摘Lead(Pb)plays a significant role in the nuclear industry and is extensively used in radiation shielding,radiation protection,neutron moderation,radiation measurements,and various other critical functions.Consequently,the measurement and evaluation of Pb nuclear data are highly regarded in nuclear scientific research,emphasizing its crucial role in the field.Using the time-of-flight(ToF)method,the neutron leakage spectra from three^(nat)Pb samples were measured at 60°and 120°based on the neutronics integral experimental facility at the China Institute of Atomic Energy(CIAE).The^(nat)Pb sample sizes were30 cm×30 cm×5 cm,30 cm×30 cm×10 cm,and 30 cm×30 cm×15 cm.Neutron sources were generated by the Cockcroft-Walton accelerator,producing approximately 14.5 MeV and 3.5 MeV neutrons through the T(d,n)^(4)He and D(d,n)^(3)He reactions,respectively.Leakage neutron spectra were also calculated by employing the Monte Carlo code of MCNP-4C,and the nuclear data of Pb isotopes from four libraries:CENDL-3.2,JEFF-3.3,JENDL-5,and ENDF/B-Ⅷ.0 were used individually.By comparing the simulation and experimental results,improvements and deficiencies in the evaluated nuclear data of the Pb isotopes were analyzed.Most of the calculated results were consistent with the experimental results;however,a few areas did not fit well.In the(n,el)energy range,the simulated results from CENDL-3.2 were significantly overestimated;in the(n,inl)D and the(n,inl)C energy regions,the results from CENDL-3.2 and ENDF/B-Ⅷ.0 were significantly overestimated at 120°,and the results from JENDL-5 and JEFF-3.3 are underestimated at 60°in the(n,inl)D energy region.The calculated spectra were analyzed by comparing them with the experimental spectra in terms of the neutron spectrum shape and C/E values.The results indicate that the theoretical simulations,using different data libraries,overestimated or underestimated the measured values in certain energy ranges.Secondary neutron energies and angular distributions in the data files have been presented to explain these discrepancies.
基金Project supported by the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301500)the National Natural Science Foundation of China(Grant No.62105366)。
文摘Microring resonators(MRRs)are extensively utilized in photonic chips for generating quantum light sources and enabling high-efficiency nonlinear frequency conversion.However,conventional microrings are typically optimized for a single specific function,limiting their versatility in multifunctional applications.In this work,we propose a reconfigurable microring resonator architecture designed to accommodate diverse application requirements.By integrating a cascaded Mach–Zehnder interferometer(MZI)as the microring coupler,the design enables independent control of the quality factors for pump,signal and idler photons through two tunable phase shifters.This capability allows for dynamic tuning and optimization of critical performance parameters,including photon-pair generation rate(PGR),spectral purity and single photon heralding efficiency(HE).The proposed structure is implemented on a silicon photonic chip,and experimental results exhibit a wide range of tunability for these parameters,with excellent agreement with theoretical predictions.This flexible and multi-functional design offers a promising pathway for high-performance,highly integrated on-chip quantum information processing systems.
基金supported by the Natural Science Foundation of Hebei Province(Nos.D2019106042,D2020304038,and D2021106002)the National Natural Science Foundation of China(No.22276099)+1 种基金the State Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex(No.2021080544)the Environmental Monitoring Research Foundation of Jiangsu Province(No.2211).
文摘VOCs(Volatile organic compounds)exert a vital role in ozone and secondary organic aerosol production,necessitating investigations into their concentration,chemical characteristics,and source apportionment for the effective implementation of measures aimed at preventing and controlling atmospheric pollution.FromJuly to October 2020,onlinemonitoringwas conducted in the main urban area of Shijiazhuang to collect data on VOCs and analyze their concentrations and reactivity.Additionally,the PMF(positive matrix factorization)method was utilized to identify the VOCs sources.Results indicated that the TVOCs(total VOCs)concentration was(96.7±63.4μg/m^3),with alkanes exhibiting the highest concentration of(36.1±26.4μg/m^3),followed by OVOCs(16.4±14.4μg/m^3).The key active components were alkenes and aromatics,among which xylene,propylene,toluene,propionaldehyde,acetaldehyde,ethylene,and styrene played crucial roles as reactive species.The sources derived from PMF analysis encompassed vehicle emissions,solvent and coating sources,combustion sources,industrial emissions sources,as well as plant sources,the contribution of which were 37.80%,27.93%,16.57%,15.24%,and 2.46%,respectively.Hence,reducing vehicular exhaust emissions and encouraging neighboring industries to adopt low-volatile organic solvents and coatings should be prioritized to mitigate VOCs levels.
基金supported by the Special Funds for Chengde national innovation demonstration area construction of science and technology special project sustainable development agenda(No.202104F001)the National Basic Research Program of China(No.2019YFC0408602).
文摘Nitrogen removal from domestic sewage is usually limited by insufficient carbon source and electron donor.An economical solid carbon source was developed by composition of polyvinyl alcohol,sodium alginate,and corncob,which was utilized as external carbon source in the anaerobic anoxic oxic(AAO)-biofilter for the treatment of low carbon-to-nitrogen ratio domestic sewage,and the nitrogen removal was remarkably improved from 63.2%to 96.5%.Furthermore,the effluent chemical oxygen demand maintained at 35 mg/L or even lower,and the total nitrogenwas reduced to less than 2mg/L.Metagenomic analysis demonstrated that the microbial communities responsible for potential denitrification and organic matter degradation in both AAO and the biofilter reactors were mainly composed of Proteobacteria and Bacteroides,respectively.The solid carbon source addition resulted in relatively high abundance of functional enzymes responsible for NO_(3)^(−)-N to NO_(2)^(−)-N con-version in both AAO and the biofilter reactors,thus enabled stable reaction.The carbon source addition during glycolysis primarily led to the increase of genes associated with the metabolic conversion of fructose 1.6P2 to glycerol-3P The reactor maintained high abun-dance of genes related to the tricarboxylic acid cycle,and then guaranteed efficient carbon metabolism.The results indicate that the composite carbon source is feasible for denitri-fication enhancement of AAO-biofilter,which contribute to the theoretical foundation for practical nitrogen removal application.
基金supported by the National Key Research and Development Program of China(No.2022YFC3204000).
文摘Lake Baiyangdian is one of China’s largest macrophyte-derived lakes,facing severe challenges related to water quality maintenance and eutrophication prevention.Dissolved organic matter(DOM)was a huge carbon pool and its abundance,property,and transformation played important roles in the biogeochemical cycle and energy flow in lake ecosystems.In this study,Lake Baiyangdian was divided into four distinct areas:Unartificial Area(UA),Village Area(VA),Tourism Area(TA),and Breeding Area(BA).We examined the diversity of DOM properties and sources across these functional areas.Our findings reveal that DOM in this lake is predominantly composed of protein-like substances,as determined by excitation-emission matrix and parallel factor analysis(EEM-PARAFAC).Notably,the exogenous tyrosine-like component C1 showed a stronger presence in VA and BA compared to UA and TA.Ultrahigh-resolution mass spectrometry(FT-ICR MS)unveiled a similar DOM molecular composition pattern across different functional areas due to the high relative abundances of lignan compounds,suggesting that macrophytes significantly influence the material structure of DOM.DOM properties exhibited specific associations with water quality indicators in various functional areas,as indicated by the Mantel test.The connections between DOM properties and NO_(3)-N andNH3-Nwere more pronounced in VA and BA than in UA and TA.Our results underscore the viability of using DOM as an indicator for more precise and scientific water quality management.
基金supported by the National Natural Science Foundation of China(Nos.U23A2016,U1704241,and 42007175).
文摘Water-soluble organic nitrogen(WSON)affects the formation,hygroscopicity,acidity of organic aerosols,and nitrogen biogeochemical cycles.However,qualitative and quantitative characterizations of WSON remain limited due to its chemical complexity.In the study,1-year field samples of particulate matter 2.5(PM_(2.5))were collected fromJune 2022 to May 2023 to analyze the WSON concentration in PM_(2.5),and correlation analysis,positive matrix factor(PMF),and potential source contribution function(PSCF)modelswere employed to elucidate WSON source apportionment and transport pathways.The results revealed that the mean WSON concentrations reached 1.98±2.64μg/m^(3) with a mean WSON to water-soluble total nitrogen(WSTN)ratio of 21%.Further,WSON concentration exhibited a seasonal variation trend,with higher values in winter and lower in summer.Five sources were identified as contributors to WSON in PM_(2.5) within the reservoir area through a comprehensive analysis including correlation analysis,PSCF and concentration weighted trajectory(CWT),and PMF analyses.These sources were agricultural,dust,combustion,traffic,and industrial sources,of which agricultural source emerged as the primary contributor(76.69%).The atmosphere in the reservoir area were primarily influenced by the transport of northeastern air masses,local agricultural activities,industrial cities along the trajectory,and coastal regions,exerting significant influences on the concentration of WSON in the reservoir area.The findings of this study addressed the research gap concerning organic nitrogen in PM_(2.5) within the reservoir area,thereby offering a theoretical foundation and data support in controlling nitrogen pollution in the Danjiangkou Reservoir area.
基金Supported by the National Natural Science Foundation of China(No.U20A20103)the Scientific Research Fund of the Fourth Institute of Oceanography+1 种基金Guangxi Funding Project(No.304024XM20N0006)the Guangxi Talent Science and Technology Project(No.2019AC17008)。
文摘In this study,the occurrence,sources,and ecological risk of microplastics(>60μm)in the surface and bottom seawater were investigated in the Beibu Gulf,the northern South China Sea.The average abundance of microplastics in surface and bottom waters was 1.35±0.93 and 0.79±0.50 items/m~3,respectively.Microplastics in both surface and bottom waters were predominantly in the form of fragments,and mostly in green.The composition of microplastics in surface water was primarily poly(methyl methacrylate)(PMA),whereas in bottom water,polyethylene(PE)dominated.Positive matrix factorization(PMF)modeling revealed that the primary sources of microplastics were pipeline abrasion,fishing activities,plastic waste,landfill disposal,transportation,aquaculture,and construction activities.The pollution load index(PLI)indicated that the overall risk of microplastic pollution in the Beibu Gulf was low.Conversely,the polymer hazard index(PHI)for microplastics was relatively high.These data underscore the importance of timely and effective reduction of human-intensive activities contributing to microplastic pollution and provide valuable information for further research in microplastic ecotoxicology and biogeochemistry.
基金Supported by Natural Science Foundation of Fujian Province(2023J011667)Natural Science Foundation of Xiamen(3502Z202374084).
文摘Microwave digestion-inductively coupled plasma mass spectrometry(ICP-MS)was used to analyze the sources of lead in farmland soil and rice in the Jiulongjiang River Basin.The results suggested that the source of lead in rice was differ from that in soil.There were four main sources of lead in farmland soil:natural source,agricultural source,industrial source and fossil fuel source,among which natural source,agricultural source and industrial source contributed more.There were four main sources of lead in rice:natural,agricultural,industrial and fossil fuel sources,and more importantly,fossil fuel sources.The comparison of lead isotope composition with potential sources(^(206)Pb/^(207)Pb,^(208)Pb/^(206)Pb,^(208)Pb/^(207)Pb)can provide a scientific basis for the identification and treatment of heavy metal lead pollution sources in farmland soil and rice in the Jiulong River Basin.
基金supported by the National Natural Science Foundation of China(No.21976169)the National Key Research and Development Program of China(No.2022YFC3702800).
文摘To explore the multicenter characteristics of endocrine-like phthalate esters(PAEs)in household dust and propose effective control strategies for global indoor public health.An on-site observational investigation was conducted in nine Chinese cities from 2018 to 2019.A total of 246 household dust sampleswere collected and analyzed for ten PAE congeners using Gas Chromatography-Mass Spectrometry(GC-MS).Questionnaires were used to gather information on building conditions,indoor behaviors,and ventilation habits.In residential dust from the nine cities,the total concentrations of the ten PAE congeners(PAEs)ranged from 0.921 to 29097.297μg/g.Dicyclohexyl phthalate(DCHP)and di(2-ethylhexyl)phthalate(DEHP)were the dominant congeners inPAEs.Childhood exposure to PAEs through dust ingestion was four orders of magnitude higher than through inhalation,with a carcinogenic risk of 5.47×10^(−6) for DEHP exposure in household dust.HigherPAEs concentrations were associated with higher temperature,double glazing,wall paint usage,television and computer use,and indoor plant growth.This multicenter on-site investigation confirmed PAE pollution characteristics and uncovered the inacceptable risk of daily DEHP exposure in household dust under real living conditions.Effective mitigation measures based on household-related information,residential characteristics,decoration materials,and lifestyle should be taken to build a healthy household environment.
基金supported by the Henan International Science and Technology Cooperation Program(No.242102521055)the Japan Science and Technology Agency(No.JPMJCR2092)the Japan Society for the Promotion of Science(Nos.JP24H00283,JP24K21575,and JP22K18754)。
文摘This study investigates the surface effects on the operation of double-ended dislocation sources in single-crystal micropillars under compression.A comprehensive theoretical framework is formulated to derive the stress field of the source segment and the corresponding Peach-Koehler(PK)forces acting on this segment near the free surfaces.An analytical formulation is then developed to compare the source strength with and without the influence of the surface stress.The results reveal that the surface effects on the dislocation source strength are highly sensitive to the interplay between the source length and its distance from the free surface.These surface effects can either enhance or reduce the critical stress required for the source operation by up to 50%,leading to significant fluctuations in yield strength,as commonly observed in discrete dislocation dynamics simulations and experimental studies.These findings provide different interpretations for the size-dependent and stochastic yield stress behavior in face-centered cubic(FCC)micropillars.
