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Earth and Planetary Physics 2024年第2期8卷 368-374页

作者： LuHuai Jiao Xin Ma YuanNong Zhang TaiFeng Jin song fu BinBin Ni Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China

The energy spectrum of energetic electrons is a key factor representing the dynamic variations of Earth’s Van Allen radiation belts.Increased measurements have indicated that the commonly used Maxwellian and Kappa distributions are inadequate for capturing the realistic spectral distributions of radiation belt electrons.Here we adopt the Kappa-type(KT)distribution as the fitting function and perform a statistical analysis to investigate the radiation belt electron flux spectra observed by the Van Allen Probes.By calculating the optimal values of the key KT distribution parameters(i.e.,κandθ2)from the observed spectral shapes,we fit the radiation belt electron fluxes at different L-shells under different geomagnetic conditions.In this manner,we obtain typical values of the KT distribution parameters,which are statistically feasible for modeling the radiation belt electron flux profiles during either geomagnetically quiet or active periods.A comparison of the KT distribution model results with those using the Maxwellian or Kappa distribution reveals the advantage of the KT distribution for studying the overall properties of the radiation belt electron spectral distribution,which has important implications for deepening the current understanding of the radiation belt electron dynamics under evolving geomagnetic conditions.

关键词： radiation belt electron Kappa-type distribution fitting geomagnetic storm

Low Selenium and Low Protein Exacerbate Myocardial Damage in Keshan Disease by Affecting the PINK1/Parkin-mediated Mitochondrial Autophagy Pathway

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Current Medical Science 2024年第1期44卷 93-101页

作者： Li-wei ZHANG Hong-qi FENG song-bo fu Dian-jun SUN Center for Endemic Disease Control Chinese Center for Disease Control and PreventionHarbin Medical UniversityNHC Key Laboratory of Etiology and Epidemiology(Harbin Medical University)Key Lab of Etiology and EpidemiologyEducation Bureau of Heilongjiang ProvinceHarbin 150086China

Objective Keshan disease(KD)is a myocardial mitochondrial disease closely related to insufficient selenium(Se)and protein intake.PTEN induced putative kinase 1(PINK1)/Parkin mediated mitochondrial autophagy regulates various physiological and pathological processes in the body.This study aimed to elucidate the relationship between PINK1/Parkin-regulated mitochondrial autophagy and KD-related myocardial injury.Methods A low Se and low protein animal model was established.One hundred Wistar rats were randomly divided into 5 groups(control group,low Se group,low protein group,low Se+low protein group,and corn from KD area group).The JC-1 method was used to detect the mitochondrial membrane potential(MMP).ELISA was used to detect serum creatine kinase MB(CK-MB),cardiac troponin I(cTnI),and mitochondrial-glutamicoxalacetic transaminase(M-GOT)levels.RT-PCR and Western blot analysis were used to detect the expression of PINK1,Parkin,sequestome 1(P62),and microtubule-associated proteins1A/1B light chain 3B(MAP1LC3B).Results The MMP was significantly decreased and the activity of CK-MB,cTnI,and M-GOT significantly increased in each experimental group(low Se group,low protein group,low Se+low protein group and corn from KD area group)compared with the control group(P<0.05 for all).The mRNA and protein expression levels of PINK1,Parkin and MAP1LC3B were profoundly increased,and those of P62 markedly decreased in the experimental groups compared with the control group(P<0.05 for all).Conclusion Low Se and low protein levels exacerbate myocardial damage in KD by affecting the PINK1/Parkin-mediated mitochondrial autophagy pathway.

关键词： Keshan disease low selenium and low protein myocardial mitochondrial injury PTEN induced putative kinase 1(PINK1)/Parkin mitochondrial autophagy

Distribution and geochemical significance of alkylbenzenes for crude oil with different depositional environments and thermal maturities

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Petroleum Science 2024年第2期21卷 777-790页

作者： Bing-Kun Meng Dao-fu song Yuan Chen Sheng-Bao Shi School of Petroleum Engineering and Environmental Engineering Yan©an UniversityYan©an716000ShaanxiChina State Key Laboratory of Petroleum Resources and Prospecting College of GeosciencesChina University of PetroleumBeijing102249China

A total of 45 alkylbenzenes were detected and identified in crude oils with different depositional environments and thermal maturities from the Tarim Basin,Beibuwan Basin,and songliao Basin using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry(GC×GCTOFMS).By analyzing the distribution characteristics of C0-C5alkylbenzenes,it is found that the content of some alkylbenzenes varies greatly in crude oils.Based on the distribution characteristics of 1,2,4,5-tetramethylbenzene(Te MB)and 1,2,3,4-Te MB,the ratio of 1,2,4,5-Te MB to 1,2,3,4-Te MB is proposed to indicate the organic matter origin and depositional environment of ancient sediments.Oil samples originated mainly from lower hydrobiont,algae,bacteria and source rocks deposited under reducing/anoxic conditions have low 1,2,4,5-/1,2,3,4-Te MB values(less than 0.6),while oil samples originated mainly from terrestrial higher plants and source rocks deposited under oxic/sub-oxic conditions have higher 1,2,4,5-/1,2,3,4-Te MB values(greater than 1.0).The significant difference of 1,2,4,5-/1,2,3,4-Te MB values is controlled by 1,2,4,5-Te MB content.1,2,4,5-Te MB content in oils derived from source rocks deposited in oxidized sedimentary environment(greater than 1.0 mg/g whole oil)is higher than that in oils from source rocks deposited in reduced sedimentary environment(less than 1.0 mg/g whole oil).1,2,4,5-/1,2,3,4-Te MB ratio might not or slightly be affected by evaporative fractionation,biodegradation and thermal maturity.1,2,4,5-/1,2,3,4-Te MB ratio and 1,2,4,5-Te MB content can be used as supplementary parameter for the identification of sedimentary environment and organic matter input.It should be noted that compared to the identification of organic matter sources,the 1,2,4,5-/1,2,3,4-Te MB parameter is more effective in identifying sedimentary environments.

关键词： 1 2 4 5-Tetramethylbenzene GC×GC-TOFMS Organic matter origin Depositional environment

A data assimilation-based forecast model of outer radiation belt electron fluxes

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Earth and Planetary Physics 2023年第6期7卷 620-630页

作者： Yuan Lei Xing Cao BinBin Ni song fu TaoRong Luo XiaoYu Wang Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China Chinese Academy of Sciences Center for Excellence in Comparative Planetology Hefei 230026China

Because radiation belt electrons can pose a potential threat to the safety of satellites orbiting in space,it is of great importance to develop a reliable model that can predict the highly dynamic variations in outer radiation belt electron fluxes.In the present study,we develop a forecast model of radiation belt electron fluxes based on the data assimilation method,in terms of Van Allen Probe measurements combined with three-dimensional radiation belt numerical simulations.Our forecast model can cover the entire outer radiation belt with a high temporal resolution(1 hour)and a spatial resolution of 0.25 L over a wide range of both electron energy(0.1-5.0 MeV)and pitch angle(5°-90°).On the basis of this model,we forecast hourly electron fluxes for the next 1,2,and 3 days during an intense geomagnetic storm and evaluate the corresponding prediction performance.Our model can reasonably predict the stormtime evolution of radiation belt electrons with high prediction efficiency(up to~0.8-1).The best prediction performance is found for~0.3-3 MeV electrons at L=~3.25-4.5,which extends to higher L and lower energies with increasing pitch angle.Our results demonstrate that the forecast model developed can be a powerful tool to predict the spatiotemporal changes in outer radiation belt electron fluxes,and the model has both scientific significance and practical implications.

关键词： Earth’s outer radiation belt data assimilation electron flux forecast model performance evaluation

Artificial modification of Earth's radiation belts by ground-based very-low-frequency(VLF)transmitters

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Science China Earth Sciences 2022年第3期65卷 391-413页

作者： Binbin NI Man HUA Xudong GU song fu Zheng XIANG Xing CAO Xin MA Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China Chinese Academy of Sciences Center for Excellence in Comparative Planetology Hefei 230026China

Wave-particle interactions play a fundamental role in the dynamic variability of Earth’s donut-shaped radiation belts that are highly populated by magnetically trapped energetic particles and characteristically separated by the slot devoid of high energetic electrons.Owing to the continuous accumulation of high-quality wave and particle measurements from multiple satellites in geospace,the important contribution of ground-based very-low-frequency(VLF)transmitter waves to the electron dynamics in the near-Earth space has been unprecedently advanced,in addition to those established findings of the significant effects of a variety of naturally occurring magnetospheric waves.This paper focuses on the artificial modification of Earth’s inner radiation belt and slot by artificial VLF transmitter emissions.We review the global distributions of VLF transmitter waves in geospace,their scattering effects on radiation belt electrons in terms of both theoretical and observational analyses,and diffusion simulation results of wave-particle interactions along with data-model comparisons.We start with a brief review of the radiation belt electron dynamics and an introduction of anthropogenic VLF transmitter waves.Subsequently,we review the global morphology of in situ VLF transmitter waves corresponding to different transmitter locations,including their day-night asymmetry,geographic distributions,seasonal and geomagnetic activity dependence,and wave propagation features.Existed theoretical and observational analyses of electron scattering effects by VLF transmitter waves are then reviewed to approach the underlying physics that can modulate the spatio-temporal variations of the electron radiation belts.further Fokker-Planck electron diffusion simulations and their comparisons with realistic satellite observations clearly indicate that VLF transmitter emissions can effectively remove energetic electrons to produce a radially bifurcated electron belt,thereby quantitatively confirming the direct link between operations of VLF tran

关键词： VLF transmitters Wave-particle interactions Electron precipitation Earth’s radiation belts Flux bifurcation

Distribution of O^(+)and O_(2)^(+) fluxes and their escape rates in the near-Mars magnetotail:A survey of MAVEN observations

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Earth and Planetary Physics 2022年第6期6卷 536-545页

作者： HengLe Du Xing Cao BinBin Ni song fu Xin Ma XiaoTong Yun MinYi Long Qiong Luo Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China Chinese Academy of Sciences Center for Excellence in Comparative PlanetologyHefei 230026China

Tailward ion outflows in the Martian-induced magnetotail are known to be one of the major channels for Martian atmospheric escape.On the basis of nearly 6.5 years of observations from the Mars Atmosphere and Volatile EvolutioN(MAVEN)mission,we investigate the statistical distribution of tailward and Marsward fluxes of heavy ions(i.e.,O^(+),and O_(2)^(+))in the near-Mars magnetotail and explore their characteristic responses to the corotating interaction region(CIR),solar wind dynamic pressure,and local magnetic field intensity.Our results show that the tailward fluxes of oxygen ions and molecular oxygen ions in the magnetotail are significantly greater than their Marsward fluxes and that the tailward flux of molecular oxygen ions is generally larger than that of oxygen ions.furthermore,the tailward ion flux distribution exhibits dependence on the CIR,solar wind dynamic pressure,and local magnetic field strength in a manner stronger than the Marsward ion flux distribution.According to the distribution of tailward ion fluxes,we calculate the corresponding escape rates of heavy ions and show that when the CIR occurs,the total escape rates of oxygen ions and molecular oxygen ions increase by a factor of~2 and~1.2,respectively.We also find that the escape rates of heavy ions increase with the enhancement of solar wind dynamic pressure,whereas the overall effect of the local magnetic field is relatively weak.Our study has important implications for improved understanding of the underlying mechanisms responsible for the Martian atmospheric escape and the evolution of the Martian atmospheric climate.

关键词： Martian-induced magnetotail atmospheric heavy ion outflow corotating interaction region escape rate

Investigations of an enclosed annular rotor-stator system with LES method

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Science China(Physics,Mechanics & Astronomy) 2018年第11期61卷 50-60页

作者： Zhe Jiao song fu School of Aerospace Engineering Tsinghua University

In this study, the flows in an enclosed annular rotor-stator system with the Reynolds number ranging from 0.75×105 to 3.75×105 and an aspect ratio of 36.5 are investigated using the LES method. Few studies have explored such a rotor-stator system with this aspect ratio and the flow structure on the rotor side. The mean flow structure varies from a torsional Couette type to a Batchelor type as the Reynolds number increases. The onset of the instability in the B?dewadt layer adjacent to the stator is delayed,whereas it is promoted in the Ekman layer adjacent to the rotor. Both the layers demonstrate rich spiral structures. Turbulent spirals are observed to occur at the rotor disk side that also generates TS-wave-like(Tollmien-Schlichting) structures between adjacent spiral arms. further, the turbulence at the stator is complex and interesting. Statistically, the turbulence is highly anisotropic near both the rotating and nonrotating disks, which is depicted by the Reynolds stresses.

关键词：定子系统 LES 转子环形流动结构不稳定性各向异性邻近

Forward-facing steps induced transition in a subsonic boundary layer

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Science China(Physics,Mechanics & Astronomy) 2017年第10期60卷 34-44页

作者： Hui Zhu song fu School of Aerospace Engineering Tsinghua University Beijing 100084 China

A forward-facing step (FFS) immersed in a subsonic boundary layer is studied through a high-order flux reconstruction (FR) method to highlight the flow transition induced by the step. The step height is a third of the local boundary-layer thickness. The Reynolds number based on the step height is 720. Inlet disturbances are introduced giving rise to streamwise vortices upstream of the step. It is observed that these small-scale streamwise structures interact with the step and hairpin vortices are quickly developed after the step leading to flow transition in the boundary layer.

关键词：边界层厚度台阶高度亚音速跃迁诱导前向边界层转捩雷诺兹数

Numerical investigation of separation-induced transition in a lowpressure turbine cascade in a low-disturbance environment

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Science China(Physics,Mechanics & Astronomy) 2020年第6期63卷 66-82页

作者： Si-Ya Jiang song fu School of Aerospace Engineering Tsinghua UniversityBeijing 100084China

In this paper,the separation-induced transition in an LPT(low-pressure turbine)cascade is investigated at low Reynolds number with DNS(direct numerical simulation).The transition process is accurately predicted giving good agreements between the DNS and experimental results.To illustrate the secondary instability of separation-induced transition in a low-disturbance environment,the results are comprehensively analyzed in both Fourier space and physical space.It is illustrated that the effect of hyperbolic instability dominates around the saddle point of hyperbolic streamlines.This instability mechanism is responsible for the emergence of the streamwise vortices in the braid region.Elongated and intensified because of the“stretching”effect of the background flow,these vortices become the most noticeable characteristic of the flow field.fundamental modes of small spanwise wavelength are excited in the braid region,so as some low-frequency modes.The elliptical instability plays a minor role than hyperbolic instability.It is also observed that the fundamental mode with a larger spanwise wavelength is unstable in the vortex core which is associated with the deformation of the vortex core via elliptical instability.There is no convincing evidence for the existence of subharmonic instability.

关键词： separation direct numerical simulation transition to turbulence

Modeling the energetic electron fluxes in the inner radiation belt based on a drift-source model

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Earth and Planetary Physics 2023年第1期7卷 100-108页

作者： Zheng Xiang BinBin Ni YangXiZi Liu XuDong Gu song fu Wei Xu Xing Cao Xin Ma DeYu Guo JunHu Dong JingLe Hu Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China

The Macao Science Satellite-1(MSS-1),designed by the Macao University of Science and Technology and the National Space Science Center(NSSC)of China,is equipped to detect the fine structure of the magnetic field over the South Atlantic Anomaly(SAA)region,monitoring geomagnetic field variations,and obtaining the energetic electron spectrum distributions in the Earth’s inner radiation belt.In this study,we simulate the distributions of trapped,quasi-trapped,and untrapped electrons along the orbit of MSS-1 based on a drift-source model.The simulation results show that the particle detector with 90°looking direction can observe trapped electrons in the SAA region,untrapped electrons in the regions conjugated with the SAA region at the north hemisphere,and quasitrapped electrons in all other regions.In contrast,the detectors with<60°looking directions can measure only untrapped electrons.Generally,quasi-trapped electron fluxes accumulate along the drift trajectory and are due primarily to CRAND,until reaching the SAA region where quasi-trapped electrons are all lost into the atmosphere.

关键词： Earth’s inner belt drift-source model quasi-trapped electron CRAND