Pyrolytic graphite (PG) with highly aligned graphene layers,present anisotropic electrical and thermal transport behavior,which is attractive in electronic,electrocatalyst and energy storage.Such pristine PG could mee...Pyrolytic graphite (PG) with highly aligned graphene layers,present anisotropic electrical and thermal transport behavior,which is attractive in electronic,electrocatalyst and energy storage.Such pristine PG could meeting the limit of electrical conductivity (~2.5×10^(4) S·cm^(−1)),although efforts have been made for achieving high-purity sp^(2) hybridized carbon.For manipulating the electrical conductivity of PG,a facile and efficient electrochemical strategy is demonstrated to enhance electrical transport ability via reversible intercalation/de-intercalation of AlCl_(4)^(-)into the graphitic interlayers.With the stage evolution at different voltages,variable electrical and thermal transport behaviors could be achieved via controlling AlCl_(4)^(-)concentrations in the PG because of substantial variation in the electronic density of states.Such evolution leads to decoupled electrical and thermal transport (opposite variation trend) in the in-plane and out-of-plane directions,and the in-plane electrical conductivity of the pristine PG (1.25×10^(4) S·cm^(−1)) could be massively promoted to 4.09×10^(4) S·cm(AlCl_(4)^(-)intercalated PG),much better than the pristine bulk graphitic papers used for the electrical transport and electromagnetic shielding.The fundamental mechanism of decoupled transport feature and electrochemical strategy here could be extended into other anisotropic conductive bulks for achieving unusual behaviors.展开更多
Aqueous Zn metal batteries(AZMBs)with intrinsic safety,high energy density and low cost have been regarded as promising electrochemical energy storage devices.However,the parasitic reaction on metallic Zn anode and th...Aqueous Zn metal batteries(AZMBs)with intrinsic safety,high energy density and low cost have been regarded as promising electrochemical energy storage devices.However,the parasitic reaction on metallic Zn anode and the incompatibility between electrode and electrolytes lead to the deterioration of electrochemical performance of AZMBs during the cycling.The critical point to achieve the stable cycling of AZMBs is to properly regulate the zinc ion solvated structure and transfer behavior between metallic Zn anode and electrolyte.In recent years,numerous achievements have been made to resolve the formation of Zn dendrite and interface incompatible issues faced by AZMBs via optimizing the sheath structure and transport capability of zinc ions at electrode-electrolyte interface.In this review,the challenges for metallic Zn anode and electrode-electrolyte interface in AZMBs including dendrite formation and interface characteristics are presented.Following the influences of different strategies involving designing advanced electrode structu re,artificial solid electrolyte interphase(SEI)on Zn anode and electrolyte engineering to regulate zinc ion solvated sheath structure and transport behavior are summarized and discussed.Finally,the perspectives for the future development of design strategies for dendrite-free Zn metal anode and long lifespan AZMBs are also given.展开更多
The magnetic behavior and the transport behavior of La0.67-x Smx Sr0.33 MnO3 （x = 0. 00, 0. 10, 0. 20, 0. 30, 0. 40, 0. 50 and 0. 60 ） systems were studied through measuring the M-T curves, electron spin resonance ...The magnetic behavior and the transport behavior of La0.67-x Smx Sr0.33 MnO3 （x = 0. 00, 0. 10, 0. 20, 0. 30, 0. 40, 0. 50 and 0. 60 ） systems were studied through measuring the M-T curves, electron spin resonance （ ESR ） curves and ρ-T curves. The samples exhibit a long-range ferromagnetic order when x = 0. 00, 0. 10, a cluster-spin glass state when x = 0. 20 and 0. 30, and an anti-ferromagnetic state at low temperatures when x = 0. 40, 0. 50 and 0. 60. The samples of x = 0. 30 and 0.40 show phase separation at temperatures above Te. The transport behavior of the sample of x = 0. 60 becomes abnormal when the doping is high, and an insulator-metal transition occurs near To and then a metal-insulator transition occurs, which rarely appears in an ABO3 structure. It is concluded that the magnetic and electric behavior changes of the systems depend on the extra magnetism and lattice distortion effect induced by Sm doping.展开更多
A transient numerical model was established to predict the dispersion,distribution,and circulation behavior of the powder injected through the up snorkel in a Ruhrstahl–Heraeus(RH)degasser.The effects of the powder d...A transient numerical model was established to predict the dispersion,distribution,and circulation behavior of the powder injected through the up snorkel in a Ruhrstahl–Heraeus(RH)degasser.The effects of the powder diameter,the lifting gas flow rate,and the powder injection rate on the powder transport were investigated.Local powder concentration was measured by a cold model.The results showed that the predicted powder concentration agreed well with the measured.The powder injection process is divided into three periods,named dispersion period,aggregation and circulation period,and dynamically stable period according to the powder transport behavior.The powder diameter has a great effect on the particle dispersion.When the particles size changes from 30 to 500μm,the powder dispersion characteristic index changes from 0.110 to 0.741,and the ladle top zone powder mass ratio changes from 0.118 to 0.685.The powder circulation mass flow rate increases to 101.0 kg min^(-1)(150μm)and then decreases to 46.6 kg min^(-1)(500μm).Powders with a diameter of more than 220μm can change the steel flow mode in the RH degasser.Increasing the lifting gas flow could slightly improve the powder dispersion.Variation in the powder injection rate has almost no effect on the powder dispersion.展开更多
A Monte Carlo simulation technique has been used to model the electron transport' behavior, especially the electron density and energy distributions under the influence of a mirror magnetic field and a uniform ele...A Monte Carlo simulation technique has been used to model the electron transport' behavior, especially the electron density and energy distributions under the influence of a mirror magnetic field and a uniform electric field in a positive column of helium direct current(DC) gas discharge Graphs showing the electron density and energy distributions, and the percentage of electrons that reach the wall and the end of the positive column are presented. The results indicate that the mirror magnetic field can control the electron transport behavior in the positive column which are in good agreement with experimental results.展开更多
Perovskite BiMnO_3 samples are successfully synthesized by the co-precipitation method at relatively low pressure and moderate temperature.The temperature dependences of resistivity are measured and systematically inv...Perovskite BiMnO_3 samples are successfully synthesized by the co-precipitation method at relatively low pressure and moderate temperature.The temperature dependences of resistivity are measured and systematically investigated.It is shown that the electrical resistivity increases sharply with the decrease of temperature above 210 K and the fitted results demonstrate that the thermally activated conduction model is the dominant conduction mechanism for the electron transport behaviors in this temperature region.A dual conducting mechanism,i.e.,the variable range hopping and thermal activated conduction,is suggested to be responsible for the transport behaviors of BiMnO_3 in the region of 180-200 K.Moreover,the resistivity increases slightly with the decrease of temperature below 180 K and the transport is governed by the variable range hopping mechanism.展开更多
Van der Waals heterostructures are acknowledged as a decent platform for electronic and optoelectronic applications owing to their atomically flat interfaces,unprecedented flexibility and unique physical characteristi...Van der Waals heterostructures are acknowledged as a decent platform for electronic and optoelectronic applications owing to their atomically flat interfaces,unprecedented flexibility and unique physical characteristics.A twist angle between neighboring layers of two-dimensional materials renders with an additional mediator for flexible modulation of interlayer coupling and electrical structure.In this work,the carrier transport behavior of twisted moirésuperlattices based onγ-graphdiyne,which is represented as the emerging category of carbon material family,is theoretically investigated for the first time.By probing a sequence of twistedγ-graphdiyne/graphene moirésuperlattices,the sp-C is figured out to play a dominant role in manipulating the distribution of electron localization in the moirésystem.The line and ring regions are identified as the primary geometric contributors to the density of states near the Fermi level in twistedγ-graphdiyne/graphene moirésuperlattices.This twist engineering also enables to expedite quantum transport ofγ-graphdiyne/graphene heterostructures according to the nonequilibrium Green’s function.This work unambiguously decodes the twist angle dependence of interlayer coupling forγ-graphdiyne/graphene heterobilayers and highlights the considerable enhancement of transport performance subtly triggered by a small twist angle(1°),benefiting a more in-depth understanding and rational design of emerging graphyne-based quantum devices.展开更多
We have previously developed bare narrow-bore capillary chromatography. In this work, high-performance DNA separation was realized for a size range of 10–800 base pairs(bp) utilizing bare narrow-bore capillary chroma...We have previously developed bare narrow-bore capillary chromatography. In this work, high-performance DNA separation was realized for a size range of 10–800 base pairs(bp) utilizing bare narrow-bore capillary chromatography with 750 nm- radius capillaries. Separation behavior of double-stranded DNA(ds DNA) fragments was investigated over a range of eluent concentrations and elution pressures. DNA molecules were hydrodynamically separated in a size-dependent manner in free solution without any sieving matrices, with the longer fragments being eluted out from the capillary earlier. It was found that the eluent concentration variously influenced the transport behavior for different-sized DNA fragments depending upon the configuration of DNA molecules and the association of counterions. Ionic strength of the solutions strongly impacted DNA persistence length. Enhanced elution pressure could shorten analysis time with a slight loss in resolution. Excellent efficiency of two million theoretical plates per meter was achieved, which indicates the enormous potential of bare narrow-bore capillary chromatography for the analysis of DNA fragments. These findings would be useful in understanding the transport behavior of DNA fragments in confined dimensions for chromatography in free solution.展开更多
In order to describe quantitatively the cation exchange action between water and rockand the transport behavior of exchange cations in the process of sea water intrusion, a newthree-dimensional mathematical model, whi...In order to describe quantitatively the cation exchange action between water and rockand the transport behavior of exchange cations in the process of sea water intrusion, a newthree-dimensional mathematical model, which can simulte simultaneously the transport be-havior of exchange cations Na<sup>+</sup>, Mg<sup>2+</sup> and Ca<sup>2+</sup> is set up. This model is applied in prac-tice and the simulated values agree very well with the field data.展开更多
In this article, the global existence and the large time behavior of smooth solutions to the initial boundary value problem for a degenerate compressible energy transport model are established.
The mechanical properties of a superconducting composite cylinder with transport current are investigated. By adopting the exponent model, the nonlinear differential equations for flux distributions are derived. The e...The mechanical properties of a superconducting composite cylinder with transport current are investigated. By adopting the exponent model, the nonlinear differential equations for flux distributions are derived. The elastic solutions to stress, displacement and magnetostriction are analytically given. Some typical numerical results are displayed. Numerical results show that in the process of transport current reduction, tensile stress generally occurs in the outer region of the composite, and that displacement is always negative in the composite. In addition, as the applied maximal transport current exceeds the outer-cylinder critical current, a hysteresis loop of the magnetostriction exists for the full cycle of the transport current.展开更多
This paper analyzes a class of first order partial differential equations with delay (a model for the blood production system). The asymptotic behavior of solutions are studied.
The influence of heavy samarion （Sm） doping （0.40≤x≤0.60） on magnetic and electric properties of La0.67-xSmxSr0.33MnO3 was investigated by measuring the magnetization-temperature （M - T） curves, magnetization-...The influence of heavy samarion （Sm） doping （0.40≤x≤0.60） on magnetic and electric properties of La0.67-xSmxSr0.33MnO3 was investigated by measuring the magnetization-temperature （M - T） curves, magnetization-magnetic density （ M - H） curves, resistivity-temperature （ρ- T） curves and magnetoresistivity-temperature （ MR - T） curves of the samples under different temperatures. It is found that, form from long-range ferromagnetic order to spin-cluster glass with the increase of Sm doping amount, the samples transstate and anti-ferromagnetic state; and when x = 0.60, the transport property becomes abnormal under magnetic background; and the magnetic structure changes and extra magnetic coupling induced by doping leads to colossal magnetoresistance effect. The transport mechanism of metallic conduction at low temperature is mainly electron-magneton interaction and can be fitted by the formula ρ = ρ0 ＋ AT^4.5, and the insulatorlike transport mechanism on high temperature range is mainly the function of variable-range hopping and can be fitted by the formula ρ = ρ0exp（T0/T）^1/4. In the formulas above, p is resistivity, T is temperature, and A, ρ0, T0 are constants.展开更多
The polycrystalline samples La_(0.67-x)Nd_(x)Sr_(0.33)MnO_(3)(x=0.1,0.2,0.3,0.4,0.5)were prepared by standard solid-state reaction method,and the M–T curves,electron spin resonance(ESR)curves,infrared spectra,Raman s...The polycrystalline samples La_(0.67-x)Nd_(x)Sr_(0.33)MnO_(3)(x=0.1,0.2,0.3,0.4,0.5)were prepared by standard solid-state reaction method,and the M–T curves,electron spin resonance(ESR)curves,infrared spectra,Raman spectra,ρ–T curves and MR–T curves of the compounds above were measured.The results show that single phase can be obtained at different Nd substitution ratios,and with the increase in Nd doping,the magnetic structure of the system transforms from long-range ferro-magnetic order to spin cluster glass state and antiferro-magnetic state;and the phase separation appears in the samples with x=0.3 and 0.4.The transport property exhibits variation with the increase in Nd doping,and the electric behavior of the sample transforms(from metal state to insulator–metal transition,and then insulator state)is accompanied by colossal magnetoresistance(CMR)effect,which can be attributed to the different couplings of sublattices induced by Nd doping and the interface tun-neling effect related to the spin.展开更多
China Fusion Engineering Test Reactor(CFETR)is China's self-designed and ongoing next-generation fusion reactor project.Tritium confinement systems in CFETR guarantee that the radiation level remains below the saf...China Fusion Engineering Test Reactor(CFETR)is China's self-designed and ongoing next-generation fusion reactor project.Tritium confinement systems in CFETR guarantee that the radiation level remains below the safety limit during tritium handling and operation in the fuel cycle system.Our tritium technology team is responsible for studying tritium transport behavior in the CFETR tritium safety confinement systems of the National Key R&D Program of China launched in 2017,and we are conducting CFETR tritium plant safety analysis by using CFD software.In this paper,the tritium migration and removal behavior were studied under a postulated accident condition for the Tokamak Exhaust Processing system of CFETR.The quantitative results of the transport behavior of tritium in the process room and glove box during the whole accident sequence(e.g.,tritium release,alarm,isolation,and tritium removal)have been presented.The results support the detailed design and engineering demonstration-related research of CFETR tritium plant.展开更多
Hanoi’s rapid urbanization has led to a surge in private vehicle ownership, particularly motorcycles, amidst inadequate public transportation infrastructure. Despite government efforts, many still prefer motorized tr...Hanoi’s rapid urbanization has led to a surge in private vehicle ownership, particularly motorcycles, amidst inadequate public transportation infrastructure. Despite government efforts, many still prefer motorized transport, citing mobility and safety concerns, exacerbated by insufficient pedestrian infrastructure. This study examines the motivations behind this reliance on motorized vehicles, particularly motorcycles, in Hanoi. Findings reveal safety and convenience as primary factors driving motorized transport use, especially for accessing bus stations. Economic incentives could promote non-motorized travel and public transport adoption. Policy implications highlight the importance of addressing economic factors and improving access infrastructure to manage motorized vehicle reliance and foster sustainable urban mobility in Hanoi.展开更多
Previous studies have shown that electroacupuncture（EA） promotes recovery of motor function in Parkinson＇s disease（PD）. However the mechanisms are not completely understood. Clinically, the subthalamic nucleus（...Previous studies have shown that electroacupuncture（EA） promotes recovery of motor function in Parkinson＇s disease（PD）. However the mechanisms are not completely understood. Clinically, the subthalamic nucleus（STN） is a critical target for deep brain stimulation treatment of PD, and vesicular glutamate transporter 1（VGlu T1） plays an important role in the modulation of glutamate in the STN derived from the cortex. In this study,a 6-hydroxydopamine（6-OHDA）-lesioned rat model of PD was treated with 100 Hz EA for 4 weeks. Immunohistochemical analysis of tyrosine hydroxylase（TH） showed that EA treatment had no effect on TH expression in the ipsilateral striatum or substantia nigra pars compacta,though it alleviated several of the parkinsonian motor symptoms. Compared with the hemi-parkinsonian rats without EA treatment, the 100 Hz EA treatment significantly decreased apomorphine-induced rotation and increased the latency in the Rotarod test. Notably, the EA treatment reversed the 6-OHDA-induced down-regulation of VGlu T1 in the STN. The results demonstrated that EA alleviated motor symptoms and up-regulated VGlu T1 in the ipsilateral STN of hemi-parkinsonian rats, suggesting that up-regulation of VGlu T1 in the STN may be related to the effects of EA on parkinsonian motor symptoms via restoration of function in the cortico-STN pathway.展开更多
The electrical transport behavior and magnetoresistance (MR) of a polycrystalline double layered manganite La1.2Sr1.4Ba0.4Mn2O7, synthesized by the sol-gel method, are investigated in the temperature range 4.2 K - 300...The electrical transport behavior and magnetoresistance (MR) of a polycrystalline double layered manganite La1.2Sr1.4Ba0.4Mn2O7, synthesized by the sol-gel method, are investigated in the temperature range 4.2 K - 300 K. The sample exhibits an insulator-to-metal transition at 87 K (TIM) and the spin-glass (SG)-like behavior is observed below 50 K (TSG). The transport behavior is analyzed in the entire temperature range considering three different regions: paramagnetic insulating region (T>TIM), ferromagnetic metallic region (TSG IM) and antiferromagnetic insulating region (TSG) by fitting the temperature dependent resistivity data to the equations governing the conduction process in the respective temperature regions. The results show that the conduction at T>TIM follows Mott variable range hopping (VRH) process, while the two-magnon scattering process is evidenced at TSG IM which is suppressed with the applied magnetic field of 4 T. The low temperature conductivity data are also fitted with Mott VRH equation. The sample exhibits a large MR (≈45%) over a temperature range???? 5 K – 50 K and it shows ≈32% MR at 5 K with a magnetic field of 0.5 T.展开更多
基金financially supported by the National Key R&D Program of China (No. 2018YFB0104400)the National Natural Science Foundation of China (Nos. 52074036, 51725401, and 51874019)Beijing Municipal Science and Technology Commission (No. Z191100002719007)
文摘Pyrolytic graphite (PG) with highly aligned graphene layers,present anisotropic electrical and thermal transport behavior,which is attractive in electronic,electrocatalyst and energy storage.Such pristine PG could meeting the limit of electrical conductivity (~2.5×10^(4) S·cm^(−1)),although efforts have been made for achieving high-purity sp^(2) hybridized carbon.For manipulating the electrical conductivity of PG,a facile and efficient electrochemical strategy is demonstrated to enhance electrical transport ability via reversible intercalation/de-intercalation of AlCl_(4)^(-)into the graphitic interlayers.With the stage evolution at different voltages,variable electrical and thermal transport behaviors could be achieved via controlling AlCl_(4)^(-)concentrations in the PG because of substantial variation in the electronic density of states.Such evolution leads to decoupled electrical and thermal transport (opposite variation trend) in the in-plane and out-of-plane directions,and the in-plane electrical conductivity of the pristine PG (1.25×10^(4) S·cm^(−1)) could be massively promoted to 4.09×10^(4) S·cm(AlCl_(4)^(-)intercalated PG),much better than the pristine bulk graphitic papers used for the electrical transport and electromagnetic shielding.The fundamental mechanism of decoupled transport feature and electrochemical strategy here could be extended into other anisotropic conductive bulks for achieving unusual behaviors.
基金supported by the National Key Research and Development Programs(2021YFB2400400)Major Science and Technology Innovation Project of Hunan Province(2020GK10102020GK1014-4)+7 种基金National Natural Science Foundation of China(32201162)the 70th general grant of China Postdoctoral Science Foundation(2021M702947)Natural Science Foundation of Henan(232300420404)Key Scientific and Technological Project of Henan Province(232102320290,232102311156)Key Research Project Plan for Higher Education Institutions in Henan Province(24A150009,23B430011)Doctor Foundation of Henan University of Engineering(D2022002)the Science and Technology Innovation Program of Hunan Province(2023RC3154)the scientific research projects of Education Department of Hunan Province(23A0188)。
文摘Aqueous Zn metal batteries(AZMBs)with intrinsic safety,high energy density and low cost have been regarded as promising electrochemical energy storage devices.However,the parasitic reaction on metallic Zn anode and the incompatibility between electrode and electrolytes lead to the deterioration of electrochemical performance of AZMBs during the cycling.The critical point to achieve the stable cycling of AZMBs is to properly regulate the zinc ion solvated structure and transfer behavior between metallic Zn anode and electrolyte.In recent years,numerous achievements have been made to resolve the formation of Zn dendrite and interface incompatible issues faced by AZMBs via optimizing the sheath structure and transport capability of zinc ions at electrode-electrolyte interface.In this review,the challenges for metallic Zn anode and electrode-electrolyte interface in AZMBs including dendrite formation and interface characteristics are presented.Following the influences of different strategies involving designing advanced electrode structu re,artificial solid electrolyte interphase(SEI)on Zn anode and electrolyte engineering to regulate zinc ion solvated sheath structure and transport behavior are summarized and discussed.Finally,the perspectives for the future development of design strategies for dendrite-free Zn metal anode and long lifespan AZMBs are also given.
文摘The magnetic behavior and the transport behavior of La0.67-x Smx Sr0.33 MnO3 （x = 0. 00, 0. 10, 0. 20, 0. 30, 0. 40, 0. 50 and 0. 60 ） systems were studied through measuring the M-T curves, electron spin resonance （ ESR ） curves and ρ-T curves. The samples exhibit a long-range ferromagnetic order when x = 0. 00, 0. 10, a cluster-spin glass state when x = 0. 20 and 0. 30, and an anti-ferromagnetic state at low temperatures when x = 0. 40, 0. 50 and 0. 60. The samples of x = 0. 30 and 0.40 show phase separation at temperatures above Te. The transport behavior of the sample of x = 0. 60 becomes abnormal when the doping is high, and an insulator-metal transition occurs near To and then a metal-insulator transition occurs, which rarely appears in an ABO3 structure. It is concluded that the magnetic and electric behavior changes of the systems depend on the extra magnetism and lattice distortion effect induced by Sm doping.
基金supported by the National Natural Science Foundation of China(Grant No.U20A20272)the Fundamental Research Funds for the Central Universities,NEU(No.N2025017).
文摘A transient numerical model was established to predict the dispersion,distribution,and circulation behavior of the powder injected through the up snorkel in a Ruhrstahl–Heraeus(RH)degasser.The effects of the powder diameter,the lifting gas flow rate,and the powder injection rate on the powder transport were investigated.Local powder concentration was measured by a cold model.The results showed that the predicted powder concentration agreed well with the measured.The powder injection process is divided into three periods,named dispersion period,aggregation and circulation period,and dynamically stable period according to the powder transport behavior.The powder diameter has a great effect on the particle dispersion.When the particles size changes from 30 to 500μm,the powder dispersion characteristic index changes from 0.110 to 0.741,and the ladle top zone powder mass ratio changes from 0.118 to 0.685.The powder circulation mass flow rate increases to 101.0 kg min^(-1)(150μm)and then decreases to 46.6 kg min^(-1)(500μm).Powders with a diameter of more than 220μm can change the steel flow mode in the RH degasser.Increasing the lifting gas flow could slightly improve the powder dispersion.Variation in the powder injection rate has almost no effect on the powder dispersion.
文摘A Monte Carlo simulation technique has been used to model the electron transport' behavior, especially the electron density and energy distributions under the influence of a mirror magnetic field and a uniform electric field in a positive column of helium direct current(DC) gas discharge Graphs showing the electron density and energy distributions, and the percentage of electrons that reach the wall and the end of the positive column are presented. The results indicate that the mirror magnetic field can control the electron transport behavior in the positive column which are in good agreement with experimental results.
基金Supported by the Key Research Project of Shaanxi University of Science and Technology under Grant Nos 2016GBJ-12 and2016BJ-59
文摘Perovskite BiMnO_3 samples are successfully synthesized by the co-precipitation method at relatively low pressure and moderate temperature.The temperature dependences of resistivity are measured and systematically investigated.It is shown that the electrical resistivity increases sharply with the decrease of temperature above 210 K and the fitted results demonstrate that the thermally activated conduction model is the dominant conduction mechanism for the electron transport behaviors in this temperature region.A dual conducting mechanism,i.e.,the variable range hopping and thermal activated conduction,is suggested to be responsible for the transport behaviors of BiMnO_3 in the region of 180-200 K.Moreover,the resistivity increases slightly with the decrease of temperature below 180 K and the transport is governed by the variable range hopping mechanism.
基金supported by the National Key Research and Development Program of China(2022YFA1204502,2021YFA1200196 and 2018YFA0703503)the National Natural Science Foundation of China(52122208,52188101,52072031,51991340,51991342 and 51702014)+2 种基金the Overseas Expertise Introduction Projects for Discipline Innovation(111 Project,B14003)the State Key Laboratory for Advanced Metals and Materials(2018Z-03 and 2019Z-04)the Fundamental Research Funds for the Central Universities(QNXM20210013,FRF-TP-2021-03C1 and FRF-TP-20-008A3).
文摘Van der Waals heterostructures are acknowledged as a decent platform for electronic and optoelectronic applications owing to their atomically flat interfaces,unprecedented flexibility and unique physical characteristics.A twist angle between neighboring layers of two-dimensional materials renders with an additional mediator for flexible modulation of interlayer coupling and electrical structure.In this work,the carrier transport behavior of twisted moirésuperlattices based onγ-graphdiyne,which is represented as the emerging category of carbon material family,is theoretically investigated for the first time.By probing a sequence of twistedγ-graphdiyne/graphene moirésuperlattices,the sp-C is figured out to play a dominant role in manipulating the distribution of electron localization in the moirésystem.The line and ring regions are identified as the primary geometric contributors to the density of states near the Fermi level in twistedγ-graphdiyne/graphene moirésuperlattices.This twist engineering also enables to expedite quantum transport ofγ-graphdiyne/graphene heterostructures according to the nonequilibrium Green’s function.This work unambiguously decodes the twist angle dependence of interlayer coupling forγ-graphdiyne/graphene heterobilayers and highlights the considerable enhancement of transport performance subtly triggered by a small twist angle(1°),benefiting a more in-depth understanding and rational design of emerging graphyne-based quantum devices.
基金supported by the National Natural Science Foundation of China(21275014)the Excellent Young Scientists Fund of NSFC(21322501)+3 种基金the Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions(CIT&TCD20140309)the Program for New Century Excellent Talents in University(NCET-12-0603)the Beijing Natural Science Foundation ProgramScientific Research Key Program of Beijing Municipal Commission of Education(KZ201310005001)
文摘We have previously developed bare narrow-bore capillary chromatography. In this work, high-performance DNA separation was realized for a size range of 10–800 base pairs(bp) utilizing bare narrow-bore capillary chromatography with 750 nm- radius capillaries. Separation behavior of double-stranded DNA(ds DNA) fragments was investigated over a range of eluent concentrations and elution pressures. DNA molecules were hydrodynamically separated in a size-dependent manner in free solution without any sieving matrices, with the longer fragments being eluted out from the capillary earlier. It was found that the eluent concentration variously influenced the transport behavior for different-sized DNA fragments depending upon the configuration of DNA molecules and the association of counterions. Ionic strength of the solutions strongly impacted DNA persistence length. Enhanced elution pressure could shorten analysis time with a slight loss in resolution. Excellent efficiency of two million theoretical plates per meter was achieved, which indicates the enormous potential of bare narrow-bore capillary chromatography for the analysis of DNA fragments. These findings would be useful in understanding the transport behavior of DNA fragments in confined dimensions for chromatography in free solution.
基金Project supported by the National Natural Science Foundation of China.
文摘In order to describe quantitatively the cation exchange action between water and rockand the transport behavior of exchange cations in the process of sea water intrusion, a newthree-dimensional mathematical model, which can simulte simultaneously the transport be-havior of exchange cations Na<sup>+</sup>, Mg<sup>2+</sup> and Ca<sup>2+</sup> is set up. This model is applied in prac-tice and the simulated values agree very well with the field data.
基金Supported by the Foundation for Talents of Beijing (20081D0501500171)the Funds of Beijing University of Technology
文摘In this article, the global existence and the large time behavior of smooth solutions to the initial boundary value problem for a degenerate compressible energy transport model are established.
基金Support from the National Natural Science Foundation of China(Grant Nos.11272223 and 11072160)the Program for Changjiang Scholars and Innovative Research Team in University(IRT0971)
文摘The mechanical properties of a superconducting composite cylinder with transport current are investigated. By adopting the exponent model, the nonlinear differential equations for flux distributions are derived. The elastic solutions to stress, displacement and magnetostriction are analytically given. Some typical numerical results are displayed. Numerical results show that in the process of transport current reduction, tensile stress generally occurs in the outer region of the composite, and that displacement is always negative in the composite. In addition, as the applied maximal transport current exceeds the outer-cylinder critical current, a hysteresis loop of the magnetostriction exists for the full cycle of the transport current.
文摘This paper analyzes a class of first order partial differential equations with delay (a model for the blood production system). The asymptotic behavior of solutions are studied.
文摘The influence of heavy samarion （Sm） doping （0.40≤x≤0.60） on magnetic and electric properties of La0.67-xSmxSr0.33MnO3 was investigated by measuring the magnetization-temperature （M - T） curves, magnetization-magnetic density （ M - H） curves, resistivity-temperature （ρ- T） curves and magnetoresistivity-temperature （ MR - T） curves of the samples under different temperatures. It is found that, form from long-range ferromagnetic order to spin-cluster glass with the increase of Sm doping amount, the samples transstate and anti-ferromagnetic state; and when x = 0.60, the transport property becomes abnormal under magnetic background; and the magnetic structure changes and extra magnetic coupling induced by doping leads to colossal magnetoresistance effect. The transport mechanism of metallic conduction at low temperature is mainly electron-magneton interaction and can be fitted by the formula ρ = ρ0 ＋ AT^4.5, and the insulatorlike transport mechanism on high temperature range is mainly the function of variable-range hopping and can be fitted by the formula ρ = ρ0exp（T0/T）^1/4. In the formulas above, p is resistivity, T is temperature, and A, ρ0, T0 are constants.
基金the Key Programme of Grand Basic Research Programme of China(No.2007CB925001)the National Key Basic Research Programme of China(No.001CB610604)+1 种基金the Grand Natural Science Research Programme of Anhui Education Department(Nos.ZD2007003-1 and KJ2010A074)the Anhui Provincial Natural Science Foundation(No.1308085MA11)。
文摘The polycrystalline samples La_(0.67-x)Nd_(x)Sr_(0.33)MnO_(3)(x=0.1,0.2,0.3,0.4,0.5)were prepared by standard solid-state reaction method,and the M–T curves,electron spin resonance(ESR)curves,infrared spectra,Raman spectra,ρ–T curves and MR–T curves of the compounds above were measured.The results show that single phase can be obtained at different Nd substitution ratios,and with the increase in Nd doping,the magnetic structure of the system transforms from long-range ferro-magnetic order to spin cluster glass state and antiferro-magnetic state;and the phase separation appears in the samples with x=0.3 and 0.4.The transport property exhibits variation with the increase in Nd doping,and the electric behavior of the sample transforms(from metal state to insulator–metal transition,and then insulator state)is accompanied by colossal magnetoresistance(CMR)effect,which can be attributed to the different couplings of sublattices induced by Nd doping and the interface tun-neling effect related to the spin.
基金the National Key R&D Program of China-National Magnetic Confinement Fusion Science Program(No.2017YFE0300305).
文摘China Fusion Engineering Test Reactor(CFETR)is China's self-designed and ongoing next-generation fusion reactor project.Tritium confinement systems in CFETR guarantee that the radiation level remains below the safety limit during tritium handling and operation in the fuel cycle system.Our tritium technology team is responsible for studying tritium transport behavior in the CFETR tritium safety confinement systems of the National Key R&D Program of China launched in 2017,and we are conducting CFETR tritium plant safety analysis by using CFD software.In this paper,the tritium migration and removal behavior were studied under a postulated accident condition for the Tokamak Exhaust Processing system of CFETR.The quantitative results of the transport behavior of tritium in the process room and glove box during the whole accident sequence(e.g.,tritium release,alarm,isolation,and tritium removal)have been presented.The results support the detailed design and engineering demonstration-related research of CFETR tritium plant.
文摘Hanoi’s rapid urbanization has led to a surge in private vehicle ownership, particularly motorcycles, amidst inadequate public transportation infrastructure. Despite government efforts, many still prefer motorized transport, citing mobility and safety concerns, exacerbated by insufficient pedestrian infrastructure. This study examines the motivations behind this reliance on motorized vehicles, particularly motorcycles, in Hanoi. Findings reveal safety and convenience as primary factors driving motorized transport use, especially for accessing bus stations. Economic incentives could promote non-motorized travel and public transport adoption. Policy implications highlight the importance of addressing economic factors and improving access infrastructure to manage motorized vehicle reliance and foster sustainable urban mobility in Hanoi.
基金supported by the Beijing Municipal Science and Technology Commission (Z161100002616007)National Key Research and Development Program (2016YFC1306300)+1 种基金the Major Program of the National Natural Science Foundation of China (81527901)the Natural Science Foundation of Beijing Municipality (7082008)
文摘Previous studies have shown that electroacupuncture（EA） promotes recovery of motor function in Parkinson＇s disease（PD）. However the mechanisms are not completely understood. Clinically, the subthalamic nucleus（STN） is a critical target for deep brain stimulation treatment of PD, and vesicular glutamate transporter 1（VGlu T1） plays an important role in the modulation of glutamate in the STN derived from the cortex. In this study,a 6-hydroxydopamine（6-OHDA）-lesioned rat model of PD was treated with 100 Hz EA for 4 weeks. Immunohistochemical analysis of tyrosine hydroxylase（TH） showed that EA treatment had no effect on TH expression in the ipsilateral striatum or substantia nigra pars compacta,though it alleviated several of the parkinsonian motor symptoms. Compared with the hemi-parkinsonian rats without EA treatment, the 100 Hz EA treatment significantly decreased apomorphine-induced rotation and increased the latency in the Rotarod test. Notably, the EA treatment reversed the 6-OHDA-induced down-regulation of VGlu T1 in the STN. The results demonstrated that EA alleviated motor symptoms and up-regulated VGlu T1 in the ipsilateral STN of hemi-parkinsonian rats, suggesting that up-regulation of VGlu T1 in the STN may be related to the effects of EA on parkinsonian motor symptoms via restoration of function in the cortico-STN pathway.
文摘The electrical transport behavior and magnetoresistance (MR) of a polycrystalline double layered manganite La1.2Sr1.4Ba0.4Mn2O7, synthesized by the sol-gel method, are investigated in the temperature range 4.2 K - 300 K. The sample exhibits an insulator-to-metal transition at 87 K (TIM) and the spin-glass (SG)-like behavior is observed below 50 K (TSG). The transport behavior is analyzed in the entire temperature range considering three different regions: paramagnetic insulating region (T>TIM), ferromagnetic metallic region (TSG IM) and antiferromagnetic insulating region (TSG) by fitting the temperature dependent resistivity data to the equations governing the conduction process in the respective temperature regions. The results show that the conduction at T>TIM follows Mott variable range hopping (VRH) process, while the two-magnon scattering process is evidenced at TSG IM which is suppressed with the applied magnetic field of 4 T. The low temperature conductivity data are also fitted with Mott VRH equation. The sample exhibits a large MR (≈45%) over a temperature range???? 5 K – 50 K and it shows ≈32% MR at 5 K with a magnetic field of 0.5 T.
