1.Introduction The world today is strongly interconnected.Numerous interdependent and complex networks have been formed between environmental,economic,and social systems,through which people,resources,materials,goods,...1.Introduction The world today is strongly interconnected.Numerous interdependent and complex networks have been formed between environmental,economic,and social systems,through which people,resources,materials,goods,and information are exchanged at unprecedented speeds[1].At the same time,however,such networks are profoundly changing the global risk landscape and making the whole system more vulnerable[2].In particular,there is a growing concern about cascading and systemic risks.In such cases,a localized initial damaging event(e.g.,the coronavirus disease 2019(COVID-19)pandemic)can spread rapidly and globally,resulting in disruptive influences and countless societal costs[3].展开更多
The magnetic anisotropy manipulation in the Sm_(3)Fe_(5)O_(12)(SmIG)films and its effect on the interfacial spin coupling in the CoFe/SmIG heterostructures were studied carefully.By switching the orientation of the Gd...The magnetic anisotropy manipulation in the Sm_(3)Fe_(5)O_(12)(SmIG)films and its effect on the interfacial spin coupling in the CoFe/SmIG heterostructures were studied carefully.By switching the orientation of the Gd_(3)Ga_(5)O_(12)substrates from(111)to(001),the magnetic anisotropy of obtained SmIG films shifts from in-plane to out-of-plane.Similar results can also be obtained in the films on Gd_(3)Ga_(5)O_(12)substrates,which identifies the universality of such orientation-induced magnetic anisotropy switching.Additionally,the interfacial spin coupling and magnetic anisotropy switching effect on the spin wave in CoFe/SmIG magnetic heterojunctions have also been explored by utilizing the time-resolved magneto-optical Kerr effect technique.It is intriguing to find that both the frequency and effective damping factor of spin precession in CoFe/SmIG heterojunctions can be manipulated by the magnetic anisotropy switching of SmIG films.These findings not only provide a route for the perpendicular magnetic anisotropy acquisition but also give a further path for spin manipulation in magnetic films and heterojunctions.展开更多
With the soaring generation of hazardous waste(HW)during industrialization and urbanization,HW illegal dumping continues to be an intractable global issue.Particularly in developing regions with lax regulations,it has...With the soaring generation of hazardous waste(HW)during industrialization and urbanization,HW illegal dumping continues to be an intractable global issue.Particularly in developing regions with lax regulations,it has become a major source of soil and groundwater contamination.One dominant challenge for HW illegal dumping supervision is the invisibility of dumping sites,which makes HW illegal dumping difficult to be found,thereby causing a long-term adverse impact on the environment.How to utilize the limited historic supervision records to screen the potential dumping sites in the whole region is a key challenge to be addressed.In this study,a novel machine learning model based on the positive-unlabeled(PU)learning algorithm was proposed to resolve this problem through the ensemble method which could iteratively mine the features of limited historic cases.Validation of the random forest-based PU model showed that the predicted top 30%of high-risk areas could cover 68.1%of newly reported cases in the studied region,indicating the reliability of the model prediction.This novel framework will also be promising in other environmental management scenarios to deal with numerous unknown samples based on limited prior experience.展开更多
High-quality epitaxial LaRhO3(LRO) thin films on SrTiO3(110) single-crystalline substrates are fabricated by pulsed laser deposition and their photoconductivity properties are studied. The transient photoconductivity(...High-quality epitaxial LaRhO3(LRO) thin films on SrTiO3(110) single-crystalline substrates are fabricated by pulsed laser deposition and their photoconductivity properties are studied. The transient photoconductivity(TPC) effect is found in this semiconductor LRO film at room temperature. The magnitude of TPC increases almost linearly with the laser power intensities and the photon energies in visible light range. Moreover, the difference in the TPC results under two airflow conditions confirms that both intrinsic photoinduced carrier accumulation and extrinsic photoinduced heating effects contribute to the magnitude of TPC effect.展开更多
Aerosol particle size has a crucial impact on the environment and public health.Current satellite-based regression models focus on the total amount of particles and are limited by surface observations.This study propo...Aerosol particle size has a crucial impact on the environment and public health.Current satellite-based regression models focus on the total amount of particles and are limited by surface observations.This study proposes an algorithm to derive the long-term normalized volume size distribution(VSD)of aerosol particles,which is independent of ground measurements.The size distribution and aerosol optical depth of Multi-angle Imaging SpectroRadiometer(MISR)components are employed.We find the estimated MISR VSD is consistent with Aerosol Robotic Network(AERONET)observations,with R=0.56,0.54,0.59,and 0.68 for daily,monthly,seasonal,and annual levels.The stratified validations of radius,stations,and years further confirm the stable performance of derived VSD(R=0.28 to 0.73).The application of the random forest model demonstrates the potential improvements of predicted VSD by 10-fold cross-validation R=0.86 at the monthly level.We apply MISR VSD to quantify the normalized volume of fractional aerosol particles at a resolution of 0.2°×0.2°during 2004 to 2016 in China.We also calculate the proportion of small and medium particles to indicate the contribution of anthropogenic aerosols.The highest ratios are concentrated in the northeastern regions especially during winter while relatively lower in the Taklamakan Desert of western China.The case study demonstrates that the application of MISR data can yield valuable and resolved size distributions of aerosol particles.展开更多
The magneto-optical spectrum, with magnetic fields up to 42 T, of double layered ruthenates Ca_3(Ru_(0.91)Mn_(0.09))_2O_7(CRMO) single crystal is studied. Both the temperature and magnetic field induced insulator-to-m...The magneto-optical spectrum, with magnetic fields up to 42 T, of double layered ruthenates Ca_3(Ru_(0.91)Mn_(0.09))_2O_7(CRMO) single crystal is studied. Both the temperature and magnetic field induced insulator-to-metal transitions(IMTs) are observed via magneto-optical properties of the crystal. The critical magnetic field(H//c) of IMT for CRMO is found to be as large as 35 T at 5 K. The fine structure of optical spectra identified the antiferromagnetic/ferro-orbital-ordering configurations of Ru 4d orbitals at low temperatures. Meanwhile, the configuration of orbital polarization of such double-layer CRMO single crystal is discussed. These results suggest that the orbital degree of freedom plays an important role in the field induced IMT of multi-orbital system.展开更多
Recently discovered magnetic van der Waals(vdW)materials provide an ideal platform to explore low-dimensional magnetism and spin transport.Its vdW interaction nature opens up unprecedented opportunities to build verti...Recently discovered magnetic van der Waals(vdW)materials provide an ideal platform to explore low-dimensional magnetism and spin transport.Its vdW interaction nature opens up unprecedented opportunities to build vertically stacked heterostructures with novel properties and functionalities.By engineering the planar structure as an alternative degree of freedom,herein we demonstrate an antisymmetric magnetoresistance(MR)in a vdW Fe_(3)GeTe_(2)flake with a step terrace that breaks the planar symmetry.This antisymmetric MR originates from a sign change of the anomalous Hall effect and the continuity of the current transport near the boundary of magnetic domains at the step edge.A repeatable domain wall due to the unsynchronized magnetization switching is responsible for this sign change.Such interpretation is supported by the observation of field-dependent domain switching,and the step thickness,temperature,and magnetic field orientation dependent MR.This work opens up new opportunities to encode magnetic information by controlling the planar domain structures in vdW magnets.展开更多
The authors obtain some gradient estimates for positive solutions to the following nonlinear parabolic equation:αu/αt=△u-b(x,t)u~σ on complete noncompact manifolds with Ricci curvature bounded from below,where 0&...The authors obtain some gradient estimates for positive solutions to the following nonlinear parabolic equation:αu/αt=△u-b(x,t)u~σ on complete noncompact manifolds with Ricci curvature bounded from below,where 0<σ<1 is a real constant,and b(x,t) is a function which is C^2 in the x-variable and C^1 in the t-variable.展开更多
China has experienced rapid urbanization in recent decades along with dramatic economic growth. Previous studies have shown that urbanization has both positive and negative effects on health. However, there is a lack ...China has experienced rapid urbanization in recent decades along with dramatic economic growth. Previous studies have shown that urbanization has both positive and negative effects on health. However, there is a lack of research on the overall effects of urbanization on the epidemic transition of environmental health risks considering various pathways in China. In the present study, we studied the contributions of different aspects of urbanization in China to epidemic transitions using provincial and multi-year （1995, 2000, 2005, and 2010） panel data. Statistical models with fixed and random effects were developed to explore the impacts of different urbanization indicators on the overall epidemic tran- sition of environmental health （general model） and the changes in cause-specific mortality rates of typ- ical diseases （cause-specific models）. The results show that the impacts of non-communicable diseases continue to grow during the urbanization process in China. The ratio of communicable disease-related mortality to non-communicable disease-related mortality continues to decrease over time. The general model shows that the improved medical conditions （coefficient =-0.0011, P= 0.037）, the improved urban infrastructure （e.g., tap water supply） （coefficient = -0.00065, P 〈 0,001）, and the rise in income （coefficient = -0.00027, P = 0.047） during the urbanization process are important factors that promote this overall epidemic transition. The cause-specific models show that the mechanisms behind the general model are complicated. More attention should be paid to non-communicable diseases in urban health management. Specific health policies for different diseases should incorporate the considerations of dif- ferent impact pathwavs of urbanization,展开更多
基金This work was supported by the National Natural Science Foundation of China(71921003 and 71761147002)the Major Consulting Research Project of the Chinese Academy of Engineering(2019-ZD-33).
文摘1.Introduction The world today is strongly interconnected.Numerous interdependent and complex networks have been formed between environmental,economic,and social systems,through which people,resources,materials,goods,and information are exchanged at unprecedented speeds[1].At the same time,however,such networks are profoundly changing the global risk landscape and making the whole system more vulnerable[2].In particular,there is a growing concern about cascading and systemic risks.In such cases,a localized initial damaging event(e.g.,the coronavirus disease 2019(COVID-19)pandemic)can spread rapidly and globally,resulting in disruptive influences and countless societal costs[3].
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0303603 and 2016YFA0401803)the National Natural Science Foundation of China(Grant Nos.U2032218,11574316,11874120,61805256,and 11904367)+1 种基金the Plan for Major Provincial Science&Technology Project(Grant No.202003a05020018)the Key Research Program of Frontier Sciences,CAS(Grant No.QYZDB-SSW-SLH011)。
文摘The magnetic anisotropy manipulation in the Sm_(3)Fe_(5)O_(12)(SmIG)films and its effect on the interfacial spin coupling in the CoFe/SmIG heterostructures were studied carefully.By switching the orientation of the Gd_(3)Ga_(5)O_(12)substrates from(111)to(001),the magnetic anisotropy of obtained SmIG films shifts from in-plane to out-of-plane.Similar results can also be obtained in the films on Gd_(3)Ga_(5)O_(12)substrates,which identifies the universality of such orientation-induced magnetic anisotropy switching.Additionally,the interfacial spin coupling and magnetic anisotropy switching effect on the spin wave in CoFe/SmIG magnetic heterojunctions have also been explored by utilizing the time-resolved magneto-optical Kerr effect technique.It is intriguing to find that both the frequency and effective damping factor of spin precession in CoFe/SmIG heterojunctions can be manipulated by the magnetic anisotropy switching of SmIG films.These findings not only provide a route for the perpendicular magnetic anisotropy acquisition but also give a further path for spin manipulation in magnetic films and heterojunctions.
基金the National Natural Science Foundation of China(71761147002,71921003,and 52270199)Jiangsu R&D Special Fund for Carbon Peaking and Carbon Neutrality(BK20220014)State Key Laboratory of Pollution Control and Resource Reuse(PCRRZZ-202109).
文摘With the soaring generation of hazardous waste(HW)during industrialization and urbanization,HW illegal dumping continues to be an intractable global issue.Particularly in developing regions with lax regulations,it has become a major source of soil and groundwater contamination.One dominant challenge for HW illegal dumping supervision is the invisibility of dumping sites,which makes HW illegal dumping difficult to be found,thereby causing a long-term adverse impact on the environment.How to utilize the limited historic supervision records to screen the potential dumping sites in the whole region is a key challenge to be addressed.In this study,a novel machine learning model based on the positive-unlabeled(PU)learning algorithm was proposed to resolve this problem through the ensemble method which could iteratively mine the features of limited historic cases.Validation of the random forest-based PU model showed that the predicted top 30%of high-risk areas could cover 68.1%of newly reported cases in the studied region,indicating the reliability of the model prediction.This novel framework will also be promising in other environmental management scenarios to deal with numerous unknown samples based on limited prior experience.
基金Supported by the National Key R&D Program of China under Grant Nos 2017YFA0303603 and 2016YFA0401803the National Natural Science Foundation of China under Grant Nos 11574316,U1532155,61805256 and U1832106the Key Research Program of Frontier Sciences of CAS under Grant No QYZDB-SSW-SLH011
文摘High-quality epitaxial LaRhO3(LRO) thin films on SrTiO3(110) single-crystalline substrates are fabricated by pulsed laser deposition and their photoconductivity properties are studied. The transient photoconductivity(TPC) effect is found in this semiconductor LRO film at room temperature. The magnitude of TPC increases almost linearly with the laser power intensities and the photon energies in visible light range. Moreover, the difference in the TPC results under two airflow conditions confirms that both intrinsic photoinduced carrier accumulation and extrinsic photoinduced heating effects contribute to the magnitude of TPC effect.
基金supported by the National Natural Science Foundation of China(72234003,71921003,and 71761147002)the Jiangsu Natural Science Foundation of China(BK20160624).
文摘Aerosol particle size has a crucial impact on the environment and public health.Current satellite-based regression models focus on the total amount of particles and are limited by surface observations.This study proposes an algorithm to derive the long-term normalized volume size distribution(VSD)of aerosol particles,which is independent of ground measurements.The size distribution and aerosol optical depth of Multi-angle Imaging SpectroRadiometer(MISR)components are employed.We find the estimated MISR VSD is consistent with Aerosol Robotic Network(AERONET)observations,with R=0.56,0.54,0.59,and 0.68 for daily,monthly,seasonal,and annual levels.The stratified validations of radius,stations,and years further confirm the stable performance of derived VSD(R=0.28 to 0.73).The application of the random forest model demonstrates the potential improvements of predicted VSD by 10-fold cross-validation R=0.86 at the monthly level.We apply MISR VSD to quantify the normalized volume of fractional aerosol particles at a resolution of 0.2°×0.2°during 2004 to 2016 in China.We also calculate the proportion of small and medium particles to indicate the contribution of anthropogenic aerosols.The highest ratios are concentrated in the northeastern regions especially during winter while relatively lower in the Taklamakan Desert of western China.The case study demonstrates that the application of MISR data can yield valuable and resolved size distributions of aerosol particles.
基金supported by the National Key R&D Program of China (2017YFA0303603 and 2016YFA0401803)the National Natural Science Foundation of China (U1532153, U1532155, 11574316 and 11774352)+5 种基金the Key Research Program of Frontier Sciences, CAS (QYZDB-SSW-SLH011)Innovative Program of Hefei Science Center CAS (2016FXCX002 and 2016HSC-IU006)the Major Program of Development Foundation of Hefei Center for Physical Science and Technology (2016FXZY001)the One Thousand Youth Talents Program of ChinaWork at Nanjing University was supported by the National Natural Science Foundation of China (11304149 and U1332205)was supported by the Fundamental Research Funds for the Central Universities of China
文摘The magneto-optical spectrum, with magnetic fields up to 42 T, of double layered ruthenates Ca_3(Ru_(0.91)Mn_(0.09))_2O_7(CRMO) single crystal is studied. Both the temperature and magnetic field induced insulator-to-metal transitions(IMTs) are observed via magneto-optical properties of the crystal. The critical magnetic field(H//c) of IMT for CRMO is found to be as large as 35 T at 5 K. The fine structure of optical spectra identified the antiferromagnetic/ferro-orbital-ordering configurations of Ru 4d orbitals at low temperatures. Meanwhile, the configuration of orbital polarization of such double-layer CRMO single crystal is discussed. These results suggest that the orbital degree of freedom plays an important role in the field induced IMT of multi-orbital system.
基金the National Key Research and Development Program of China(No.2017YFA0402902)the National Natural Science Foundation of China(No.1210041089)+1 种基金National Synchrotron Radiation Laboratory(No.KY2060000177),NJUPT-SF(No.NY220163)the US NSF(No.DMR-2005108).
文摘Recently discovered magnetic van der Waals(vdW)materials provide an ideal platform to explore low-dimensional magnetism and spin transport.Its vdW interaction nature opens up unprecedented opportunities to build vertically stacked heterostructures with novel properties and functionalities.By engineering the planar structure as an alternative degree of freedom,herein we demonstrate an antisymmetric magnetoresistance(MR)in a vdW Fe_(3)GeTe_(2)flake with a step terrace that breaks the planar symmetry.This antisymmetric MR originates from a sign change of the anomalous Hall effect and the continuity of the current transport near the boundary of magnetic domains at the step edge.A repeatable domain wall due to the unsynchronized magnetization switching is responsible for this sign change.Such interpretation is supported by the observation of field-dependent domain switching,and the step thickness,temperature,and magnetic field orientation dependent MR.This work opens up new opportunities to encode magnetic information by controlling the planar domain structures in vdW magnets.
基金supported by the Jiangsu Provincial Natural Science Foundation of China(No.BK20140804)the Fundamental Research Funds of the Central Universities(No.NS2014076)
文摘The authors obtain some gradient estimates for positive solutions to the following nonlinear parabolic equation:αu/αt=△u-b(x,t)u~σ on complete noncompact manifolds with Ricci curvature bounded from below,where 0<σ<1 is a real constant,and b(x,t) is a function which is C^2 in the x-variable and C^1 in the t-variable.
基金supported by the National Natural Science Foundation of China(71433007)the National Key Research and Development Program of China(2016YFC0207603)supported by China Scholarship Council(CSC)under the State Scholarship Fund
文摘China has experienced rapid urbanization in recent decades along with dramatic economic growth. Previous studies have shown that urbanization has both positive and negative effects on health. However, there is a lack of research on the overall effects of urbanization on the epidemic transition of environmental health risks considering various pathways in China. In the present study, we studied the contributions of different aspects of urbanization in China to epidemic transitions using provincial and multi-year （1995, 2000, 2005, and 2010） panel data. Statistical models with fixed and random effects were developed to explore the impacts of different urbanization indicators on the overall epidemic tran- sition of environmental health （general model） and the changes in cause-specific mortality rates of typ- ical diseases （cause-specific models）. The results show that the impacts of non-communicable diseases continue to grow during the urbanization process in China. The ratio of communicable disease-related mortality to non-communicable disease-related mortality continues to decrease over time. The general model shows that the improved medical conditions （coefficient =-0.0011, P= 0.037）, the improved urban infrastructure （e.g., tap water supply） （coefficient = -0.00065, P 〈 0,001）, and the rise in income （coefficient = -0.00027, P = 0.047） during the urbanization process are important factors that promote this overall epidemic transition. The cause-specific models show that the mechanisms behind the general model are complicated. More attention should be paid to non-communicable diseases in urban health management. Specific health policies for different diseases should incorporate the considerations of dif- ferent impact pathwavs of urbanization,
