Due to its unique layered structure and excellent electrochemical properties,molybdenum disulfide(MoS_(2))demonstrates significant potential for applications in the energy storage field,particularly in supercapacitors...Due to its unique layered structure and excellent electrochemical properties,molybdenum disulfide(MoS_(2))demonstrates significant potential for applications in the energy storage field,particularly in supercapacitors.It is widely regarded as one of the most representative transition metal dichalcogenides.MoS_(2)possesses a high theoretical specific capacitance,abundant edge active sites,and favorable tunability and structural diversity,which provide it with a distinct advantage in the construction of advanced electrode structures.Additionally,the anisotropic characteristics of MoS_(2)concerning electron and ion transport offer more dimensions for regulating its electrochemical behavior.This work will systematically review various synthesis strategies for MoS_(2)and its recent advancements in energy storage,with a particular focus on the mechanisms by which interlayer spacing modulation affects energy storage behavior in supercapacitor configurations.The discussion will encompass a comprehensive logical framework that spans material structure modifications,electronic configuration evolution,and enhancements in macroscopic device performance.This review aims to provide theoretical support and practical guidance for the application of MoS_(2)in the next generation of highperformance energy storage devices.展开更多
Hot flow anomalies(HFAs)are not only a terrestrial phenomenon,but also a solar-system-wide phenomenon,one that can cause significant perturbations in planetary magnetospheres and ionospheres.In this study,based on the...Hot flow anomalies(HFAs)are not only a terrestrial phenomenon,but also a solar-system-wide phenomenon,one that can cause significant perturbations in planetary magnetospheres and ionospheres.In this study,based on the observations of Mars Atmosphere and Volatile EvolutioN(MAVEN)mission in the region upstream of the Martian bow shock from the year 2014 to 2020,we have investigated the statistical properties of HFAs around Mars.Our results show that HFAs can be found in a wide region of Mars,from the dayside to the terminator region.On average,these HFAs last 63 seconds,with a thickness of 28 local proton gyroradii.They are more prevalent when the ambient solar wind is denser and faster,and usually occur when the interplanetary magnetic field magnitude is between 1-4 nT.Martian HFAs can also lead to solar wind dynamics multiplying in pressure by factors of ten within only tens of seconds,which could significantly influence the heights of the Martian ionopause and induced magnetosphere boundary.By comparing HFAs around Earth,we suggest that these phenomena are primarily governed by solar wind dynamics rather than local planetary conditions.展开更多
Evidence indicates that metabolic reprogramming characterized by the changes in cellular metabolic patterns contributes to the pathogenesis of pulmonary fibrosis (PF). It is considered as a promising therapeutic targe...Evidence indicates that metabolic reprogramming characterized by the changes in cellular metabolic patterns contributes to the pathogenesis of pulmonary fibrosis (PF). It is considered as a promising therapeutic target anti-PF. The well-documented against PF properties of Tanshinone IIA (Tan IIA) have been primarily attributed to its antioxidant and anti-inflammatory potency. Emerging evidence suggests that Tan IIA may target energy metabolism pathways, including glycolysis and tricarboxylic acid (TCA) cycle. However, the detailed and advanced mechanisms underlying the anti-PF activities remain obscure. In this study, we applied [U-13C]-glucose metabolic flux analysis (MFA) to examine metabolism flux disruption and modulation nodes of Tan IIA in PF. We identified that Tan IIA inhibited the glycolysis and TCA flux, thereby suppressing the production of transforming growth factor-β1 (TGF-β1)-dependent extracellular matrix and the differentiation and proliferation of myofibroblasts in vitro. We further revealed that Tan IIA inhibited the expression of key metabolic enzyme hexokinase 2 (HK2) by inhibiting phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR)/hypoxia-inducible factor 1α (HIF-1α) pathway activities, which decreased the accumulation of abnormal metabolites. Notably, we demonstrated that Tan IIA inhibited ATP citrate lyase (ACLY) activity, which reduced the collagen synthesis pathway caused by cytosol citrate consumption. Further, these results were validated in a mouse model of bleomycin-induced PF. This study was novel in exploring the mechanism of the occurrence and development of Tan IIA in treating PF using 13C-MFA technology. It provided a novel understanding of the mechanism of Tan IIA against PF from the perspective of metabolic reprogramming.展开更多
The particle velocity distribution in space plasma usually exhibits a non-Maxwellian high-energy tail that can be well modeled by kappa distributions.In this study,we focus on the growth rates of the Alfvén-cyclo...The particle velocity distribution in space plasma usually exhibits a non-Maxwellian high-energy tail that can be well modeled by kappa distributions.In this study,we focus on the growth rates of the Alfvén-cyclotron instability driven by ion temperature anisotropy in a kappa plasma.By solving the kinetic linear dispersion equation,we explore the sensitivity of growth rates to the spectral indexκof a bi-kappa distribution under different plasma conditions,including a variety of plasma beta β_(hp) and temperature anisotropy A_(hp) values of hot protons.Furthermore,a concise,analytic scaling formula is derived that relates the dimensionless maximum growth rate to three independent variables:the spectral index and the plasma beta and temperature anisotropy of hot protons.Our results show that as theκ-value increases,the instability bandwidth narrows and the maximum growth rate increases significantly.For higherβ_(hp)and A_(hp)′the maximum instability undergoes a sharp increase as well.When our fits of dimensionless maximum growth rates are compared with solutions to kinetic linear dispersion theory,the results generally exhibit good agreement between them.Especially under the circumstances of largeκ-values and highβ_(hp)and A_(hp)′the scalings of maximum growth rates primarily accurately model the numerical solutions.Our analytic expressions can readily be used in large-scale models of the Earth’s magnetosphere to understand wave generation due to the Alfvén-cyclotron instability.展开更多
With Venus Express magnetic field measurements at 32 Hz from 2006 to 2012, we investigate statistically the magnetic fluctuations in the near-Venusian space. The global spatial distribution of their spectral scaling f...With Venus Express magnetic field measurements at 32 Hz from 2006 to 2012, we investigate statistically the magnetic fluctuations in the near-Venusian space. The global spatial distribution of their spectral scaling features is presented in MHD and kinetic regimes. It can be observed that turbulence is a common phenomenon in the solar wind in both regimes. The solar wind MHD turbulence is modified at the Venusian bow shock;MHD turbulence is absent in the Venusian magnetosheath but present at the magnetosheath boundary layer. Pre-existing kinetic turbulence from the far upstream solar wind is modified in the near solar wind region, while kinetic turbulence can be extensively observed throughout the Venusian magnetosheath and in some regions of the induced magnetosphere. Our results reveal that, in the near-Venusian space, energy cascade can be developed at the boundary between magnetosheath and wake, and the turbulence-related dissipation of magnetic energy occurs extensively in the magnetosheath and the induced magnetosphere.展开更多
Geomagnetic storms can result in large magnetic field disturbances and intense currents in the magnetosphere and even on the ground.As an important medium of momentum and energy transport among the solar wind,magnetos...Geomagnetic storms can result in large magnetic field disturbances and intense currents in the magnetosphere and even on the ground.As an important medium of momentum and energy transport among the solar wind,magnetosphere,and ionosphere,field-aligned currents(FACs)can also be strengthened in storm times.This study shows the responses of FACs in the plasma sheet boundary layer(PSBL)observed by the Magnetospheric Multiscale(MMS)spacecraft in different phases of a large storm that lasted from May 27,2017,to May 29,2017.Most of the FACs were carried by electrons,and several FACs in the storm time also contained sufficient ion FACs.The FAC magnitudes were larger in the storm than in the quiet period,and those in the main phase were the strongest.In this case,the direction of the FACs in the main phase showed no preference for tailward or earthward,whereas the direction of the FACs in the recovery phase was mostly tailward.The results suggest that the FACs in the PSBL are closely related to the storm and could be driven by activities in the tail region,where the energy transported from the solar wind to the magnetosphere is stored and released as the storm is evolving.Thus,the FACs are an important medium of energy transport between the tail and the ionosphere,and the PSBL is a significant magnetosphere–ionosphere coupling region in the nightside.展开更多
This paper has analyzed allelopathic effects ofNerium indicum on Oncomelania hupensis through triterpene sapogenins, a potential molluscicide. The snails were treated under six various concentrations （0, 20, 40, 60, ...This paper has analyzed allelopathic effects ofNerium indicum on Oncomelania hupensis through triterpene sapogenins, a potential molluscicide. The snails were treated under six various concentrations （0, 20, 40, 60, 80, 100 mg/L） of triterpene sapogenins and five periods （1, 2, 3, 4, 5 days）. The mortality of snails was positively correlated with the concentration of triterpene sapogenins and exposure time. The results ofprobit analysis showed that the LD50 （Lethal Dose, 50%） oftriterpenoid saponins from N. indicum by immersion for 2, 3, 4, 5 days were 78.31, 30.26, 20.50, 14.19 mg/L, respectively. And the corresponding 95% confidence intervals were 63.60-108.19, 9.49-44.42, 2.86-30.90, 0.23-22.79 mg/L, respectively. The observations of both scanning electron microscope and transmission electron microscope proved that 40 mg/L triterpene sapogenins could cause apparent damage to the structure of soft tissue, liver and intestine of O. hupensis. The esterase （EST） isozyme electrophoresis in liver of O. hupensis treated by 40 mg/L of the concentrations lixivium of the triterpene sapogenins from N. indicum was analyzed for 24, 48, 72, 96, 120 h, respectively. The activity of enzyme was higher than control water group after been treated up to 24-48 h, and then lowered and disappeared after 72 h. It was implicated that the extracted triterpene sapogenin from N. indicum were promising for controlling the snail, which were also providing the foundation for constructing plant community of oleander to control O. hupensis.展开更多
Magnetic holes are magnetic depression structures that exist widely in many plasma environments.The magnetic holes with durations of>1 s in the solar wind at Mercury’s orbit have drawn much attention,but the prope...Magnetic holes are magnetic depression structures that exist widely in many plasma environments.The magnetic holes with durations of>1 s in the solar wind at Mercury’s orbit have drawn much attention,but the properties of the magnetic holes with shorter durations are still unclear.Here,we investigate the magnetic holes with durations of 0.1-100 s in the upstream region of Mercury’s bow shock based on observations by the MESSENGER(MErcury Surface,Space ENvironment,GEochemistry,and Ranging)spacecraft.They can be divided into two groups according to the distribution of their duration:small-duration magnetic holes(SDMHs,<0.6 s)and large-duration magnetic holes(LDMHs,>0.6 s).The duration of each group approximately obeys a log-normal distribution with a median of~0.25 s and 3 s,respectively.Approximately 1.7%(32.6%)of the SDMHs(LDMHs)reduce the magnetic field strength by more than 50%.For both groups,some structures have a linear or quasi-linear polarization,whereas others have an elliptical polarization.The magnetic hole events in both groups tend to have a higher rate of occurrence when the interplanetary magnetic field strength is weaker.Their occurrence rates are also affected by Mercury’s foreshock,which can increase(decrease)the occurrence rate of the SDMHs(LDMHs).This finding suggests that Mercury’s foreshock might be one source of the SDMHs and that the foreshock can destroy some LDMHs.These observations suggest that a new group of magnetic holes with durations of<0.6 s exist in the upstream region of Mercury’s bow shock.展开更多
This paper considers the regularity of solutions to mixed boundary value problems in small-angle regions for elliptic equations. By constructing a specific barrier function, we proved that under the assumption of suff...This paper considers the regularity of solutions to mixed boundary value problems in small-angle regions for elliptic equations. By constructing a specific barrier function, we proved that under the assumption of sufficient regularity of boundary conditions and coefficients, as long as the angle is sufficiently small, the regularity of the solution to the mixed boundary value problem of the second-order elliptic equation can reach any order.展开更多
CO_(2)photoreduction to high-valued CH_(4)is highly attractive,whereas the CH_(4)selectivity and activity,especially under atmospheric CO_(2),is still unsatisfying.Here,we design spatially-separated redox sites on two...CO_(2)photoreduction to high-valued CH_(4)is highly attractive,whereas the CH_(4)selectivity and activity,especially under atmospheric CO_(2),is still unsatisfying.Here,we design spatially-separated redox sites on two-dimensional heterostructured nanosheets with loaded metal oxides,thus achieving high reactivity and selectivity of photocatalytic atmospheric CO_(2)reduction to CH_(4).Taking the synthetic In_(2)O_(3)/In_(2)S_(3)nanosheets with loaded PdO quantum dots as a prototype,quasi in-situ X-ray photoelectron spectra reveal the Pd sites accumulate photogenerated holes for dissociating H_(2)O and the In sites accept photoexcited electrons to activate CO_(2).Moreover,the Pd-OD bond is confirmed by in-situ Fourier-transform infrared spectra during the D2O labeling experiment,indicating the PdO quantum dots participate in H_(2)O oxidation to supply hydrogen species for CO_(2)methanation.As a result,in a simulated air atmosphere,the PdO-In_(2)O_(3)/In_(2)S_(3)nanosheets enable favorable atmospheric CO_(2)-to CH_(4)photoreduction with nearly 100%selectivity and ultralong stability of 240 h as well as CO_(2)conversion of 48.2%.This study opens an approach towards designing photocatalysts with spatially-separated redox sites to achieve efficient oxidation and reduction of CO_(2)photocatalysis to CH_(4).展开更多
Image super-resolution (SR) is one of the classic computer vision tasks. This paper proposes a super-resolution network based on adaptive frequency component upsampling, named SR-AFU. The network is composed of multip...Image super-resolution (SR) is one of the classic computer vision tasks. This paper proposes a super-resolution network based on adaptive frequency component upsampling, named SR-AFU. The network is composed of multiple cascaded dilated convolution residual blocks (CDCRB) to extract multi-resolution features representing image semantics, and multiple multi-size convolutional upsampling blocks (MCUB) to adaptively upsample different frequency components using CDCRB features. The paper also defines a new loss function based on the discrete wavelet transform, making the reconstructed SR images closer to human perception. Experiments on the benchmark datasets show that SR-AFU has higher peak signal to noise ratio (PSNR), significantly faster training speed and more realistic visual effects compared with the existing methods.展开更多
Photocatalytic CH_(4) coupling into high-valued C_(2)H_(6) is highly attractive,whereas the photosynthetic rate,especially under oxygen-free system,is still unsatisfying.Here,we designed the negatively charged metal s...Photocatalytic CH_(4) coupling into high-valued C_(2)H_(6) is highly attractive,whereas the photosynthetic rate,especially under oxygen-free system,is still unsatisfying.Here,we designed the negatively charged metal supported on metal oxide nanosheets to activate the inert C-H bond in CH_(4)and hence accelerate CH_(4) coupling performance.As an example,the synthetic Au/ZnO porous nanosheets exhibit the C_(2)H_(6) photosynthetic rate of 1,121.6μmol g^(-1)_(cat)h^(-1)and the CH_(4) conversion rate of 2,374.6μmol g^(-1)_(cat)h^(-1) under oxygen-free system,2 orders of magnitude higher than those of previously reported photocatalysts.By virtue of several in situ spectroscopic techniques,it is established that the generated Au^(δ-)and O^-species together polarized the C-H bond,while the Au^(δ-)and O^-species jointly stabilized the CH_(3) intermediates,which favored the coupling of CH_(3) intermediate to photosynthesize C_(2)H_(6) instead of overoxidation into CO_(x).Thus,the design of dual active species is beneficial for achieving high-efficient CH_(4)-to-C_(2)H_(6) photoconversion.展开更多
The CO_(2)reduction into carbon-contained fuel via solar energy offers the powerful tools to realize the zero-emission carbon cycle.Owing to the intriguing features of the two-dimensional(2D)heterostructures,it is sus...The CO_(2)reduction into carbon-contained fuel via solar energy offers the powerful tools to realize the zero-emission carbon cycle.Owing to the intriguing features of the two-dimensional(2D)heterostructures,it is susceptible to modulate the electronic structure as well as the surface geometry for optimizing the photocatalytic CO_(2)reactivity.From this perspective,we surveyed the fundamental insights of 2D semiconductor heterostructures,involving the fabrication strategies and classification of the 2D semiconductor heterostructure.Also,we have detailly discussed the overview of 2D semiconductor heterostructure for optimizing CO_(2)photocatalytic influenced factors,including the solar energy utilization,photogenerated carriers separation,and redox reaction kinetics.Afterwards,we showed the significant advantages of 2D heterostructures in elevating CO_(2)photoreduction performance,focusing on activity,selectivity and photostability.By analyzing the limitations and developments,we ended by putting forward insights into the further researches about the CO_(2)photocatalysts and reactor design,even industrial applications.展开更多
High-rate CO_(2)-to-CH_(4)photoreduction with high selectivity is highly attractive,which is a win-win strategy for mitigating the greenhouse effect and the energy crisis.However,the poor photocatalytic activity and l...High-rate CO_(2)-to-CH_(4)photoreduction with high selectivity is highly attractive,which is a win-win strategy for mitigating the greenhouse effect and the energy crisis.However,the poor photocatalytic activity and low product selectivity hinder the practical application.To precisely tailor the product selectivity and realize high-rate CO_(2)photoreduction,we design atomically precise Pd species supported on In_(2)O_(3)nanosheets.Taking the synthetic 1.30Pd/In_(2)O_(3)nanosheets as an example,the aberration-correction high-angle annular dark-field scanning transmission electron microscopy image displayed the Pd species atomically dispersed on the In_(2)O_(3)nanosheets.Raman spectra and X-ray photoelectron spectra established that the strong interaction between the Pd species and the In_(2)O_(3)substrate drove electron transfer from In to Pd species,resulting in electron-enriched Pd sites for CO_(2)activation.Synchrotronradiation photoemission spectroscopy demonstrated that the Pd species can tailor the conduction band edge of In_(2)O_(3)nanosheets to match the CO_(2)-to-CH_(4)pathway,instead of the CO_(2)-to-CO pathway,which theoretically accounts for the high CH_(4)selectivity.Moreover,in situ X-ray photoelectron spectroscopy unveiled that the catalytically active sites had a change from In species to Pd species over the 1.30Pd/In_(2)O_(3)nanosheets.In situ FTIR and EPR spectra reveal the atomically precise Pd species with rich electrons prefer to adsorb the electrophilic protons for accelerating the*COOH intermediates hydrogenation into CH_(4).Consequently,the 1.30Pd/In_(2)O_(3)nanosheets reached CO_(2)-to-CH_(4)photoconversion with 100%selectivity and 81.2μmol g^(−1)h^(−1)productivity.展开更多
文摘Due to its unique layered structure and excellent electrochemical properties,molybdenum disulfide(MoS_(2))demonstrates significant potential for applications in the energy storage field,particularly in supercapacitors.It is widely regarded as one of the most representative transition metal dichalcogenides.MoS_(2)possesses a high theoretical specific capacitance,abundant edge active sites,and favorable tunability and structural diversity,which provide it with a distinct advantage in the construction of advanced electrode structures.Additionally,the anisotropic characteristics of MoS_(2)concerning electron and ion transport offer more dimensions for regulating its electrochemical behavior.This work will systematically review various synthesis strategies for MoS_(2)and its recent advancements in energy storage,with a particular focus on the mechanisms by which interlayer spacing modulation affects energy storage behavior in supercapacitor configurations.The discussion will encompass a comprehensive logical framework that spans material structure modifications,electronic configuration evolution,and enhancements in macroscopic device performance.This review aims to provide theoretical support and practical guidance for the application of MoS_(2)in the next generation of highperformance energy storage devices.
基金supported by NSFC grants 42274219,42330207,42374213 and 42130204Shenzhen Key Laboratory Launching Project(No.ZDSYS20210702140800001)+1 种基金supported by Frontier Science Center of matter behave in space environmentthe support of the National Key Research and Development Program of China(No.2022YFA1604600).
文摘Hot flow anomalies(HFAs)are not only a terrestrial phenomenon,but also a solar-system-wide phenomenon,one that can cause significant perturbations in planetary magnetospheres and ionospheres.In this study,based on the observations of Mars Atmosphere and Volatile EvolutioN(MAVEN)mission in the region upstream of the Martian bow shock from the year 2014 to 2020,we have investigated the statistical properties of HFAs around Mars.Our results show that HFAs can be found in a wide region of Mars,from the dayside to the terminator region.On average,these HFAs last 63 seconds,with a thickness of 28 local proton gyroradii.They are more prevalent when the ambient solar wind is denser and faster,and usually occur when the interplanetary magnetic field magnitude is between 1-4 nT.Martian HFAs can also lead to solar wind dynamics multiplying in pressure by factors of ten within only tens of seconds,which could significantly influence the heights of the Martian ionopause and induced magnetosphere boundary.By comparing HFAs around Earth,we suggest that these phenomena are primarily governed by solar wind dynamics rather than local planetary conditions.
基金supported by the National Natural Science Foundation of China(Grant No.:82174100).
文摘Evidence indicates that metabolic reprogramming characterized by the changes in cellular metabolic patterns contributes to the pathogenesis of pulmonary fibrosis (PF). It is considered as a promising therapeutic target anti-PF. The well-documented against PF properties of Tanshinone IIA (Tan IIA) have been primarily attributed to its antioxidant and anti-inflammatory potency. Emerging evidence suggests that Tan IIA may target energy metabolism pathways, including glycolysis and tricarboxylic acid (TCA) cycle. However, the detailed and advanced mechanisms underlying the anti-PF activities remain obscure. In this study, we applied [U-13C]-glucose metabolic flux analysis (MFA) to examine metabolism flux disruption and modulation nodes of Tan IIA in PF. We identified that Tan IIA inhibited the glycolysis and TCA flux, thereby suppressing the production of transforming growth factor-β1 (TGF-β1)-dependent extracellular matrix and the differentiation and proliferation of myofibroblasts in vitro. We further revealed that Tan IIA inhibited the expression of key metabolic enzyme hexokinase 2 (HK2) by inhibiting phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR)/hypoxia-inducible factor 1α (HIF-1α) pathway activities, which decreased the accumulation of abnormal metabolites. Notably, we demonstrated that Tan IIA inhibited ATP citrate lyase (ACLY) activity, which reduced the collagen synthesis pathway caused by cytosol citrate consumption. Further, these results were validated in a mouse model of bleomycin-induced PF. This study was novel in exploring the mechanism of the occurrence and development of Tan IIA in treating PF using 13C-MFA technology. It provided a novel understanding of the mechanism of Tan IIA against PF from the perspective of metabolic reprogramming.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.42204163,42188101,42025404,42241143,41774167,41774171,41974205,41804157,41904156,42130204,and 42241133)the B-type Strategic Priority Program of the Chinese Academy of Sciences(Grant No.XDB41000000)+3 种基金the National Key R&D Program of China(Grant Nos.2022YFF0503700 and 2022YFF0503900)the pre-research projects on Civil Aerospace Technologies(Grant No.D020103)funded by the China National Space Administrationthe Macao Foundation,the Fundamental Research Funds for the Central Universities(Grant No.2042022kf1012the Shenzhen Key Laboratory Launching Project(Grant No.ZDSYS20210702140800001).TieLong Zhang was supported by the Chinese Academy of Sciences Center for Excellence in Comparative Planetology.
文摘The particle velocity distribution in space plasma usually exhibits a non-Maxwellian high-energy tail that can be well modeled by kappa distributions.In this study,we focus on the growth rates of the Alfvén-cyclotron instability driven by ion temperature anisotropy in a kappa plasma.By solving the kinetic linear dispersion equation,we explore the sensitivity of growth rates to the spectral indexκof a bi-kappa distribution under different plasma conditions,including a variety of plasma beta β_(hp) and temperature anisotropy A_(hp) values of hot protons.Furthermore,a concise,analytic scaling formula is derived that relates the dimensionless maximum growth rate to three independent variables:the spectral index and the plasma beta and temperature anisotropy of hot protons.Our results show that as theκ-value increases,the instability bandwidth narrows and the maximum growth rate increases significantly.For higherβ_(hp)and A_(hp)′the maximum instability undergoes a sharp increase as well.When our fits of dimensionless maximum growth rates are compared with solutions to kinetic linear dispersion theory,the results generally exhibit good agreement between them.Especially under the circumstances of largeκ-values and highβ_(hp)and A_(hp)′the scalings of maximum growth rates primarily accurately model the numerical solutions.Our analytic expressions can readily be used in large-scale models of the Earth’s magnetosphere to understand wave generation due to the Alfvén-cyclotron instability.
基金supported by NSFC grants 41904156, 41974205, 41774171, 41574173, 41774167 and 41804157the Science and Technology Development Fund of Macao SAR (008/2016/A1 and 039/2013/A2)+3 种基金the China Postdoctoral Science Foundation (2019M651271)the financial support of the Shenzhen Science and Technology Research Program (JCYJ20170811154933612 and JCYJ20180306171918617)the 111 Project (B18017)supported by CAS Center for Excellence in Comparative Planetology
文摘With Venus Express magnetic field measurements at 32 Hz from 2006 to 2012, we investigate statistically the magnetic fluctuations in the near-Venusian space. The global spatial distribution of their spectral scaling features is presented in MHD and kinetic regimes. It can be observed that turbulence is a common phenomenon in the solar wind in both regimes. The solar wind MHD turbulence is modified at the Venusian bow shock;MHD turbulence is absent in the Venusian magnetosheath but present at the magnetosheath boundary layer. Pre-existing kinetic turbulence from the far upstream solar wind is modified in the near solar wind region, while kinetic turbulence can be extensively observed throughout the Venusian magnetosheath and in some regions of the induced magnetosphere. Our results reveal that, in the near-Venusian space, energy cascade can be developed at the boundary between magnetosheath and wake, and the turbulence-related dissipation of magnetic energy occurs extensively in the magnetosheath and the induced magnetosphere.
基金funded by the National Natural Science Foundation of China(NSFCGrant Nos.42204177,42274219,41974205,42130204,42241155,and 42241133)+5 种基金the Guangdong Basic and Applied Basic Research Foundation-Natural Science Foundation of Guangdong(Grant Nos.2022A1515010257,2022A1515011698,and 2023A1515030132)the Shenzhen Science and Technology Research Program(Grant Nos.JCYJ20210324121403009 and JCYJ20210324121412034)the Macao foundation,the Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2022041)the Shenzhen Key Laboratory Launching Project(Grant No.ZDSYS20210702140800001)the pre-research project on Civil Aerospace Technologies(Grant No.D020103)funded by the China National Space Administration.YuanQiang Chen was also funded by China Postdoctoral Science Foundation(Grant No.2022M720944)supported by the Chinese Academy of Sciences Center for Excellence in Comparative Planetology.
文摘Geomagnetic storms can result in large magnetic field disturbances and intense currents in the magnetosphere and even on the ground.As an important medium of momentum and energy transport among the solar wind,magnetosphere,and ionosphere,field-aligned currents(FACs)can also be strengthened in storm times.This study shows the responses of FACs in the plasma sheet boundary layer(PSBL)observed by the Magnetospheric Multiscale(MMS)spacecraft in different phases of a large storm that lasted from May 27,2017,to May 29,2017.Most of the FACs were carried by electrons,and several FACs in the storm time also contained sufficient ion FACs.The FAC magnitudes were larger in the storm than in the quiet period,and those in the main phase were the strongest.In this case,the direction of the FACs in the main phase showed no preference for tailward or earthward,whereas the direction of the FACs in the recovery phase was mostly tailward.The results suggest that the FACs in the PSBL are closely related to the storm and could be driven by activities in the tail region,where the energy transported from the solar wind to the magnetosphere is stored and released as the storm is evolving.Thus,the FACs are an important medium of energy transport between the tail and the ionosphere,and the PSBL is a significant magnetosphere–ionosphere coupling region in the nightside.
基金Acknowledgments The authors would like to thank the National Natural Science Foundation of China （grant No. 30471506, 30570322, 39670654, 30671818） and the Science and Technology Foundation of Forest （No. 2006BAD03AI 5） for providing funds to the research.
文摘This paper has analyzed allelopathic effects ofNerium indicum on Oncomelania hupensis through triterpene sapogenins, a potential molluscicide. The snails were treated under six various concentrations （0, 20, 40, 60, 80, 100 mg/L） of triterpene sapogenins and five periods （1, 2, 3, 4, 5 days）. The mortality of snails was positively correlated with the concentration of triterpene sapogenins and exposure time. The results ofprobit analysis showed that the LD50 （Lethal Dose, 50%） oftriterpenoid saponins from N. indicum by immersion for 2, 3, 4, 5 days were 78.31, 30.26, 20.50, 14.19 mg/L, respectively. And the corresponding 95% confidence intervals were 63.60-108.19, 9.49-44.42, 2.86-30.90, 0.23-22.79 mg/L, respectively. The observations of both scanning electron microscope and transmission electron microscope proved that 40 mg/L triterpene sapogenins could cause apparent damage to the structure of soft tissue, liver and intestine of O. hupensis. The esterase （EST） isozyme electrophoresis in liver of O. hupensis treated by 40 mg/L of the concentrations lixivium of the triterpene sapogenins from N. indicum was analyzed for 24, 48, 72, 96, 120 h, respectively. The activity of enzyme was higher than control water group after been treated up to 24-48 h, and then lowered and disappeared after 72 h. It was implicated that the extracted triterpene sapogenin from N. indicum were promising for controlling the snail, which were also providing the foundation for constructing plant community of oleander to control O. hupensis.
基金the Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2022041)the National Natural Science Foundation of China(Grant Nos.42241155,41974205,42130204,and 42241133)+4 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2022A1515011698,2023A1515030132,and 2022A1515010257)the Shenzhen Science and Technology Research Program(Grant Nos.JCYJ20210324121412034 and JCYJ20210324121403009)the Shenzhen Key Laboratory Launching Project(Grant No.ZDSYS20210702140800001)the Joint Open Fund of Mengcheng National Geophysical Observatory(Grant No.MENGO-202315)the Macao Foundation,the pre-research Project on Civil Aerospace Technologies(Grant No.D020103)funded by the China National Space Administration,and the Chinese Academy of Sciences Center for Excellence in Comparative Planetology。
文摘Magnetic holes are magnetic depression structures that exist widely in many plasma environments.The magnetic holes with durations of>1 s in the solar wind at Mercury’s orbit have drawn much attention,but the properties of the magnetic holes with shorter durations are still unclear.Here,we investigate the magnetic holes with durations of 0.1-100 s in the upstream region of Mercury’s bow shock based on observations by the MESSENGER(MErcury Surface,Space ENvironment,GEochemistry,and Ranging)spacecraft.They can be divided into two groups according to the distribution of their duration:small-duration magnetic holes(SDMHs,<0.6 s)and large-duration magnetic holes(LDMHs,>0.6 s).The duration of each group approximately obeys a log-normal distribution with a median of~0.25 s and 3 s,respectively.Approximately 1.7%(32.6%)of the SDMHs(LDMHs)reduce the magnetic field strength by more than 50%.For both groups,some structures have a linear or quasi-linear polarization,whereas others have an elliptical polarization.The magnetic hole events in both groups tend to have a higher rate of occurrence when the interplanetary magnetic field strength is weaker.Their occurrence rates are also affected by Mercury’s foreshock,which can increase(decrease)the occurrence rate of the SDMHs(LDMHs).This finding suggests that Mercury’s foreshock might be one source of the SDMHs and that the foreshock can destroy some LDMHs.These observations suggest that a new group of magnetic holes with durations of<0.6 s exist in the upstream region of Mercury’s bow shock.
文摘This paper considers the regularity of solutions to mixed boundary value problems in small-angle regions for elliptic equations. By constructing a specific barrier function, we proved that under the assumption of sufficient regularity of boundary conditions and coefficients, as long as the angle is sufficiently small, the regularity of the solution to the mixed boundary value problem of the second-order elliptic equation can reach any order.
基金supported by the National Key Research and Development Program of China(2022YFA1502904,2019YFA0210004,2021YFA1501502)the National Natural Science Foundation of China(22125503,21975242,U2032212,21890754,22002148)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB36000000)the Youth Innovation Promotion Association of Chinese Academy of Sciences(CX2340007003)the University Synergy Innovation Program of Anhui Province(GXXT-2020-001)
文摘CO_(2)photoreduction to high-valued CH_(4)is highly attractive,whereas the CH_(4)selectivity and activity,especially under atmospheric CO_(2),is still unsatisfying.Here,we design spatially-separated redox sites on two-dimensional heterostructured nanosheets with loaded metal oxides,thus achieving high reactivity and selectivity of photocatalytic atmospheric CO_(2)reduction to CH_(4).Taking the synthetic In_(2)O_(3)/In_(2)S_(3)nanosheets with loaded PdO quantum dots as a prototype,quasi in-situ X-ray photoelectron spectra reveal the Pd sites accumulate photogenerated holes for dissociating H_(2)O and the In sites accept photoexcited electrons to activate CO_(2).Moreover,the Pd-OD bond is confirmed by in-situ Fourier-transform infrared spectra during the D2O labeling experiment,indicating the PdO quantum dots participate in H_(2)O oxidation to supply hydrogen species for CO_(2)methanation.As a result,in a simulated air atmosphere,the PdO-In_(2)O_(3)/In_(2)S_(3)nanosheets enable favorable atmospheric CO_(2)-to CH_(4)photoreduction with nearly 100%selectivity and ultralong stability of 240 h as well as CO_(2)conversion of 48.2%.This study opens an approach towards designing photocatalysts with spatially-separated redox sites to achieve efficient oxidation and reduction of CO_(2)photocatalysis to CH_(4).
基金supported by the National Natural Science Foundation of China(Grant Nos.61603197 and 61772284)Natural Science Foundation of Nanjing University of Posts and Telecommunications(NY221071).
文摘Image super-resolution (SR) is one of the classic computer vision tasks. This paper proposes a super-resolution network based on adaptive frequency component upsampling, named SR-AFU. The network is composed of multiple cascaded dilated convolution residual blocks (CDCRB) to extract multi-resolution features representing image semantics, and multiple multi-size convolutional upsampling blocks (MCUB) to adaptively upsample different frequency components using CDCRB features. The paper also defines a new loss function based on the discrete wavelet transform, making the reconstructed SR images closer to human perception. Experiments on the benchmark datasets show that SR-AFU has higher peak signal to noise ratio (PSNR), significantly faster training speed and more realistic visual effects compared with the existing methods.
基金supported by the National Key R&D Program of China(2019YFA0210004,2022YFA1502904,2021YFA1501502)the National Natural Science Foundation of China(22125503,21975242,U2032212,21890754,22002148)+1 种基金2023 Synchrotron Radiation Joint Fund of USTCthe Youth Innovation Promotion Association of CAS(CX2340007003)。
文摘Photocatalytic CH_(4) coupling into high-valued C_(2)H_(6) is highly attractive,whereas the photosynthetic rate,especially under oxygen-free system,is still unsatisfying.Here,we designed the negatively charged metal supported on metal oxide nanosheets to activate the inert C-H bond in CH_(4)and hence accelerate CH_(4) coupling performance.As an example,the synthetic Au/ZnO porous nanosheets exhibit the C_(2)H_(6) photosynthetic rate of 1,121.6μmol g^(-1)_(cat)h^(-1)and the CH_(4) conversion rate of 2,374.6μmol g^(-1)_(cat)h^(-1) under oxygen-free system,2 orders of magnitude higher than those of previously reported photocatalysts.By virtue of several in situ spectroscopic techniques,it is established that the generated Au^(δ-)and O^-species together polarized the C-H bond,while the Au^(δ-)and O^-species jointly stabilized the CH_(3) intermediates,which favored the coupling of CH_(3) intermediate to photosynthesize C_(2)H_(6) instead of overoxidation into CO_(x).Thus,the design of dual active species is beneficial for achieving high-efficient CH_(4)-to-C_(2)H_(6) photoconversion.
基金financially supported by the National Key R&D Program of China(2019YFA0210004,2022YFA1502904,2022YFA1203600)National Natural Science Foundation of China(22125503,52394201,22321001,U2032212)。
文摘The CO_(2)reduction into carbon-contained fuel via solar energy offers the powerful tools to realize the zero-emission carbon cycle.Owing to the intriguing features of the two-dimensional(2D)heterostructures,it is susceptible to modulate the electronic structure as well as the surface geometry for optimizing the photocatalytic CO_(2)reactivity.From this perspective,we surveyed the fundamental insights of 2D semiconductor heterostructures,involving the fabrication strategies and classification of the 2D semiconductor heterostructure.Also,we have detailly discussed the overview of 2D semiconductor heterostructure for optimizing CO_(2)photocatalytic influenced factors,including the solar energy utilization,photogenerated carriers separation,and redox reaction kinetics.Afterwards,we showed the significant advantages of 2D heterostructures in elevating CO_(2)photoreduction performance,focusing on activity,selectivity and photostability.By analyzing the limitations and developments,we ended by putting forward insights into the further researches about the CO_(2)photocatalysts and reactor design,even industrial applications.
基金the National Key R&D Program of China(2022YFA1502904,2019YFA0210004,2021YFA1501502)National Natural Science Foundation of China(22125503,21975242,U2032212,21890754)+1 种基金Youth Innovation Promotion Association of CAS(CX2340007003)Technical Talent Promotion Plan(TS2021002).
文摘High-rate CO_(2)-to-CH_(4)photoreduction with high selectivity is highly attractive,which is a win-win strategy for mitigating the greenhouse effect and the energy crisis.However,the poor photocatalytic activity and low product selectivity hinder the practical application.To precisely tailor the product selectivity and realize high-rate CO_(2)photoreduction,we design atomically precise Pd species supported on In_(2)O_(3)nanosheets.Taking the synthetic 1.30Pd/In_(2)O_(3)nanosheets as an example,the aberration-correction high-angle annular dark-field scanning transmission electron microscopy image displayed the Pd species atomically dispersed on the In_(2)O_(3)nanosheets.Raman spectra and X-ray photoelectron spectra established that the strong interaction between the Pd species and the In_(2)O_(3)substrate drove electron transfer from In to Pd species,resulting in electron-enriched Pd sites for CO_(2)activation.Synchrotronradiation photoemission spectroscopy demonstrated that the Pd species can tailor the conduction band edge of In_(2)O_(3)nanosheets to match the CO_(2)-to-CH_(4)pathway,instead of the CO_(2)-to-CO pathway,which theoretically accounts for the high CH_(4)selectivity.Moreover,in situ X-ray photoelectron spectroscopy unveiled that the catalytically active sites had a change from In species to Pd species over the 1.30Pd/In_(2)O_(3)nanosheets.In situ FTIR and EPR spectra reveal the atomically precise Pd species with rich electrons prefer to adsorb the electrophilic protons for accelerating the*COOH intermediates hydrogenation into CH_(4).Consequently,the 1.30Pd/In_(2)O_(3)nanosheets reached CO_(2)-to-CH_(4)photoconversion with 100%selectivity and 81.2μmol g^(−1)h^(−1)productivity.
