In this paper, we study the dynamics of the synchronous totally asymmetric simple exclusion process （TASEP） on lattices with two consecutive junctions in a multiple-input-multiple-output （MIMO） traffic system, whi...In this paper, we study the dynamics of the synchronous totally asymmetric simple exclusion process （TASEP） on lattices with two consecutive junctions in a multiple-input-multiple-output （MIMO） traffic system, which consists of m sub-chains for the input and the output, respectively. In the middle of the system, there are n （n 〈 m） sub-chains via two consecutive junctions linking m sub-chains of input and m sub-chains of output, respectively. This configuration is a type of complex geometry that is relevant to many biological processes as well as to vehicular traffic flow. We use a mean-field approach to calculate this typical geometry and obtain the theoretical results for stationary particle currents, density profiles, and a phase diagram. With the values of m and n synchronously increasing, the vertical phase boundary moves toward the right and the horizontal phase boundary moves toward the upside in the phase diagram. The boundary conditions of the system as well as the numbers of input and output determine the no-equilibrium stationary states, stationary-states phases, and phase boundaries. We use the results to compare with computer simulations and find that they are in very good agreement with each other.展开更多
With an extensive range of distinctive features at nano meter-scale thicknesses,two-dimensional(2D)materials drawn the attention of the scientific community.Despite tremendous advancements in exploratory research on 2...With an extensive range of distinctive features at nano meter-scale thicknesses,two-dimensional(2D)materials drawn the attention of the scientific community.Despite tremendous advancements in exploratory research on 2D materials,knowledge of 2D electrical transport and carrier dynamics still in its infancy.Thus,here we highlighted the electrical characteristics of 2D materials with electronic band structure,electronic transport,dielectric constant,carriers mobility.The atomic thinness of 2D materials makes substantially scaled field-effect transistors(FETs)with reduced short-channel effects conceivable,even though strong carrier mobility required for high performance,low-voltage device operations.We also discussed here about factors affecting 2D materials which easily enhanced the activity of those materials for various applications.Presently,Those 2D materials used in state-of-the-art electrical and optoelectronic devices because of the extensive nature of their electronic band structure.2D materials offer unprecedented freedom for the design of novel p-n junction device topologies in contrast to conventional bulk semiconductors.We also,describe the numerous 2D p-n junctions,such as homo junction and hetero junction including mixed dimensional junctions.Finally,we talked about the problems and potential for the future.展开更多
We study theoretically the electrical shot noise properties of tunnel junctions between a normal metal and a superconductor with the mixture of singlet s-wave and chiral triplet p-wave pairing due to broken inversion ...We study theoretically the electrical shot noise properties of tunnel junctions between a normal metal and a superconductor with the mixture of singlet s-wave and chiral triplet p-wave pairing due to broken inversion symmetry. We investigate how the shot noise properties vary as the relative amplitude between the two parity components in the pairing potential is changed. It is demonstrated that some characteristics of the electrical shot noise properties of such tunnel junctions may depend sensitively on the relative amplitude between the two parity components in the pairing potential, and some significant changes may occur in the electrical shot noise properties when the relative amplitude between the two parity components is varied from the singlet s-wave pairing dominated regime to the chiral triplet p-wave pairing dominated regime. In the chiral triplet p-wave pairing dominated regime, the ratio of noise power to electric current is close to 2e both in the in-gap and in the out-gap region. In the singlet s-wave pairing dominated regime, the value of this ratio is close to 4e in the inner gap region but may reduce to about 2e in the outer gap region as the relative amplitude of the chiral triplet pairing component is increased. The variations of the differential shot noise with the bias voltage also exhibit some significantly different features in different regimes. Such different features can serve as useful diagnostic tools for the determination of the relative magnitude of the two parity components in the pairing potential.展开更多
This paper studies two-dimensional analysis of the surface state effect on current gain for a 4H-SiC bipolar junction transistor （BJT）. Simulation results indicate the mechanism of current gain degradation, which is...This paper studies two-dimensional analysis of the surface state effect on current gain for a 4H-SiC bipolar junction transistor （BJT）. Simulation results indicate the mechanism of current gain degradation, which is surface Fermi level pinning leading to a strong downward bending of the energy bands to form the channel of surface electron recombination current. The experimental results are well-matched with the simulation, which is modeled by exponential distributions of the interface state density replacing the single interface state trap. Furthermore, the simulation reveals that the oxide quality of the base emitter junction interface is very important for 4H-SiC BJT performance.展开更多
The influence of low-vacuum helium cold plasma treatment on the rooting percentage,root growth and physiochemical properties of zoysiagrass stolon cuttings was studied.Zoysiagrass stolon cuttings were pre-treated with...The influence of low-vacuum helium cold plasma treatment on the rooting percentage,root growth and physiochemical properties of zoysiagrass stolon cuttings was studied.Zoysiagrass stolon cuttings were pre-treated with 0,100,200,300 and 400 W of cold plasma for 15 s.The cold plasma positively stimulated rooting and improved the root growth of the zoysiagrass stolon cuttings,and the 300 W treatment produced the best effect.The rooting percentage and root growth parameters,including the root length,total root surface area,total root volume,average root diameter,and root dry weight,significantly improved in response to the cold plasma treatment.In addition,the water uptake and relative conductivity of the stolon cuttings increased significantly in response to the cold plasma treatment.The results revealed that cold plasma-stimulated rooting and root growth appear to be a consequence of the improvement in permeability and water absorbing capacity of zoysiagrass stolon cuttings.The results of the present study will provide inspiration and support for the application of cold plasma in the vegetative propagation of plants.展开更多
Establishing highly effective charge transfer channels in carbon nitride(g-C_(3)N_(4)) to enhance its photocatalytic activity is still a challenging issue.Herein,the delaminated 2D Ti_(3)C_(2) MXene nanosheets were em...Establishing highly effective charge transfer channels in carbon nitride(g-C_(3)N_(4)) to enhance its photocatalytic activity is still a challenging issue.Herein,the delaminated 2D Ti_(3)C_(2) MXene nanosheets were employed to decorate the P-doped tubular g-C_(3)N_(4)(PTCN)for engineering 1D/2D Schottky heterojunction(PTCN/TC)through electrostatic self-assembly.The optimized PTCN/TC exhibited the highest hydrogen evolution rate(565 μmol h^(-1)g^(-1)),which was 4.3 and 2.0-fold higher than pristine bulk g-C_(3)N_(4) and PTCN,respectively.Such enhancement may be primarily attributed to the phosphorus heteroatom doped and unique structure of 1D/2D g-C_(3)N_(4)/Ti_(3)C_(2) Schottky heterojunction,enhancing the light-harvesting and charges’separation.One-dimensional pathway of g-C_(3)N_(4) tube and built-in electric field of interfacial Schottky effect can significantly facilitate the spatial separation of photogenerated charge carriers,and simultaneously inhibit their recombination via Schottky barrier.In this composite,metallic Ti_(3)C_(2) was served as electrons sink and photons collector.Moreover,ultrathin Ti_(3)C_(2) flake with exposed terminal metal sites as a co-catalyst exhibited higher photocatalytic reactivity in H2 evolution compared to carbon materials(such as reduced graphene oxide).This work not only proposed the mechanism of tubular g-C_(3)N_(4)/Ti_(3)C_(2) Schottky junction in photocatalysis,but also provided a feasible way to load ultrathin Ti_(3)C_(2) as a co-catalyst for designing highly efficient photocatalysts.展开更多
In machining the particle reinforced aluminum based composite material with high Si content using the cobalt-cemented tungsten carbide micro cutting tools, diamond like carbon （DLC） films are deposited on cobalt-cem...In machining the particle reinforced aluminum based composite material with high Si content using the cobalt-cemented tungsten carbide micro cutting tools, diamond like carbon （DLC） films are deposited on cobalt-cemented tungsten carbide micro-drills with two-step pretreatment method. Characteristics of DLC coated tools are investigated in bias-enhanced HFCVD system with the optimized hot filament arrangement. The optimization deposition technology is obtained and the wear mechanism of cutting tools is analyzed. The drilling performance of DLC coated tools is verified by the experiments of cutting particle reinforced aluminum based composite material （Si 15% in volume） compared with uncoated ones. Experimental results show that the two-step pretreatment method is appropriate for complex shaped cemented carbide substrates and ensures the good adhesive strength between the diamond film and the substrate. The cutting performance of DLC coated tool is enhanced 10 times when machining the Si particle reinforced aluminum based metal matrix composite compared with that of uncoated ones under the same cutting conditions.展开更多
Rational engineering of semiconductor photocatalysts for efficient hydrogen production is of great significance but still challenging,primarily due to the limitations in charge transfer kinetics.Herein,a fascinating p...Rational engineering of semiconductor photocatalysts for efficient hydrogen production is of great significance but still challenging,primarily due to the limitations in charge transfer kinetics.Herein,a fascinating plasmonic tandem heterojunction with the hc-CdS/Mo_(2)C@C heterostructure is aimfully prepared for effectively promoting the charge separation kinetics of the CdS photocatalyst via the synergistic strategy of phase junction,Schottky junction,and photothermal effect.The difference in atomic configuration between cubic-CdS (c-CdS) and hexagonal-CdS (h-CdS) leads to effective charge separation through a typical Ⅱ charge transfer mechanism,and plasmonic Schottky junction further extracts the electrons in the hc-CdS phase junction to realize gradient charge transfer.Besides,the photothermal effect of Mo_(2)C@C helps to expand the light absorption,accelerate charge transfer kinetics,and reduce the hydrogen evolution energy barrier.The carbon layer provides a fast channel for charge transfer and protects the photocatalyst from photocorrosion.As a result,the optimized hc-CMC photocatalyst exhibits a significantly high photocatalytic H_(2)production activity of 28.63 mmol/g/h and apparent quantum efficiency of 61.8%,surpassing most of the reported photocatalysts.This study provides a feasible strategy to enhance the charge transfer kinetics and photocatalytic activity of CdS by constructing plasmonic tandem heterogeneous junctions.展开更多
We consider the effects of interface bound states on the electrical shot noise in tunnel junctions formed between normal metals and one-dimensional(1 D) or two-dimensional(2 D) Rashba semiconductors with proximity-ind...We consider the effects of interface bound states on the electrical shot noise in tunnel junctions formed between normal metals and one-dimensional(1 D) or two-dimensional(2 D) Rashba semiconductors with proximity-induced s-wave pairing potential. We investigate how the shot noise properties vary as the interface bound state is evolved from a non-zero energy bound state to a zero-energy bound state. We show that in both 1 D and 2 D tunnel junctions, the ratio of the noise power to the charge current in the vicinity of zero bias voltage may be enhanced significantly due to the induction of the midgap interface bound state. But as the interface bound state evolves from a non-zero energy bound state to a zero-energy bound state, this ratio tends to vanish completely at zero bias voltage in 1 D tunnel junctions, while in 2 D tunnel junctions it decreases smoothly to the usual classical Schottky value for the normal state. Some other important aspects of the shot noise properties in such tunnel junctions are also clarified.展开更多
A junction composed of ultrathin La0.9Ca0.1MnO3＋δ （LCMO） film and 1 wt.% Nb-doped SrTiO3 was fabricated and its magnetoresistance （MR） was studied and compared with LCMO film. It was found that the resistance of...A junction composed of ultrathin La0.9Ca0.1MnO3＋δ （LCMO） film and 1 wt.% Nb-doped SrTiO3 was fabricated and its magnetoresistance （MR） was studied and compared with LCMO film. It was found that the resistance of the junction has a similar dependence on magnetic field as that of the LCMO film： the curvature of R-H curves is upward above Curie temperature （Tc） and downward below TC. These behaviours strongly suggest that the rotation of ferromagnetic clusters in manganite also causes MR in the corresponding junction. This MR can be qualitatively understood by the change of the width of the barrier induced by the rotation of ferromagnetic clusters. These results suggest a possibility to obtain junctions with large low-field MR.展开更多
Application of the first junction condition to a highly symmetric spacetime was investigated recently in Chin. Phys. Left. B 546 189 2006, where a partial differential equation arising from the connection of the Rober...Application of the first junction condition to a highly symmetric spacetime was investigated recently in Chin. Phys. Left. B 546 189 2006, where a partial differential equation arising from the connection of the Robertson-Walker and the Schwarzschild-de Sitter metrics was presented, but no solutions of the equation were provided. Here we provide a proof to the statement that there exist solutions of the equation. In addition, an example of the solution and some analyses associated with this issue are presented. We find that in connecting the two metrics, there are three conditions which should be satisfied. Of these conditions, one condition constrains the place where the two metrics can take the same value for a local system whose mass is provided which marks the boundary of the system, and the other two constrain the transformation form. In realizing the connection of the two metrics, the latter two conditions are required to be satisfied only at the boundary defined by the former condition.展开更多
The magnetoresistance effect of a p-n junction under an electric field which is introduced by the gate voltage at room temperature is investigated by simulation. As auxiliary models, the Lombardi CVT model and carrier...The magnetoresistance effect of a p-n junction under an electric field which is introduced by the gate voltage at room temperature is investigated by simulation. As auxiliary models, the Lombardi CVT model and carrier generation- recombination model are introduced into a drift-diffusion transport model and carrier continuity equations. All the equa- tions are discretized by the finite-difference method and the box integration method and then solved by Newton iteration. Taking advantage of those models and methods, an abrupt junction with uniform doping is studied systematically, and the magnetoresistance as a function of doping concentration, SiO2 thickness and geometrical size is also investigated. The simulation results show that the magnetoresistance （MR） can be controlled substantially by the gate and is dependent on the polarity of the magnetic field.展开更多
In order to consider quantum transport under the influence of an electron-electron （e-e） interaction in a mesoscopic conductor,the Boltzmann equation and Poisson equation are investigated jointly.The analytical expr...In order to consider quantum transport under the influence of an electron-electron （e-e） interaction in a mesoscopic conductor,the Boltzmann equation and Poisson equation are investigated jointly.The analytical expressions of the distribution function for the Boltzmann equation and the self-consistent average potential concerned with e-e interaction are obtained,and the dielectric function appearing in the self-consistent average potential is naturally generalized beyond the Thomas-Fermi approximation.Then we apply these results to the tunneling junctions of a metal-insulator-semiconductor （MIS） in which the electrons are accumulated near the interface of the semiconductor,and we find that the e-e interaction plays an important role in the transport procedure of this system. The electronic density,electric current as well as screening Coulombic potential in this case are studied,and we reveal the time and position dependence of these physical quantities explicitly affected by the e-e interaction.展开更多
The scarcity,high cost and susceptibility to CO of Platinum severely restrict its application in alkaline hydrogen oxidation reaction(HOR).Hybridizing Pt with other transition metals provides an effective strategy to ...The scarcity,high cost and susceptibility to CO of Platinum severely restrict its application in alkaline hydrogen oxidation reaction(HOR).Hybridizing Pt with other transition metals provides an effective strategy to modulate its catalytic HOR performance,but at the cost of mass activity due to the coverage of modifiers on Pt surface.Herein,we constructed dual junctions'Pt/nitrogen-doped carbon(Pt/NC)andδ-MoC/NC to modify electronic structure of Pt via interfacial electron transfer to acquire Pt-MoC@NC catalyst with electron-deficient Pt nanoparticles,simultaneously endowing it with high mass activity and durability of alkaline HOR.Moreover,the unique structure of Pt-MoC@NC endows Pt with a high COtolerance at 1,000 ppm CO/H_(2),a quality that commercial Pt-C catalyst lacks.The theoretical calculations not only confirm the diffusion of electrons from Pt/NC to Mo C/NC could occur,but also demonstrate the negative shift of Pt d-band center for the optimized binding energies of*H,*OH and CO.展开更多
This paper proposes a thermal analytical model of current gain for bipolar junction transistor-bipolar static induction transistor （BJT-BSIT） compound device in the low current operation. It also proposes a best the...This paper proposes a thermal analytical model of current gain for bipolar junction transistor-bipolar static induction transistor （BJT-BSIT） compound device in the low current operation. It also proposes a best thermal compensating factor to the compound device that indicates the relationship between the thermal variation rate of current gain and device structure. This is important for the design of compound device to be optimized. Finally, the analytical model is found to be in good agreement with numerical simulation and experimental results. The test results demonstrate that thermal variation rate of current gain is below 10% in 25 ℃-85 ℃ and 20% in -55 ℃-25 ℃.展开更多
With their widespread utilization, cut-to-length harvesters have become a major source of ‘‘big data’’ for forest management as they constantly capture, and provide a daily flow of, information on log production a...With their widespread utilization, cut-to-length harvesters have become a major source of ‘‘big data’’ for forest management as they constantly capture, and provide a daily flow of, information on log production and assortment over large operational areas. Harvester data afford the calculation of the total log length between the stump and the last cut but not the total height of trees. They also contain the length and end diameters of individual logs but not always the diameter at breast height overbark（DBHOB） of harvested stems largely because of time lapse, operating and processing issues and other system deficiencies. Even when DBHOB is extracted from harvester data, errors and/or bias of the machine measurements due to the variation in the stump height of harvested stems from that specified for the harvester head prior to harvesting and diameter measurement errors may need to be corrected. This study developed（1） a system of equations for estimating DBHOB of trees from diameter overbark（DOB） measured by a harvester head at any height up to 3 m above ground level and（2） an equation to predict the total height of harvested stems in P. radiata plantations from harvester data. To generate the data required for this purpose, cut-to-length simulations of more than 3000 trees with detailed taper measurements were carried out in the computer using the cutting patterns extracted from the harvester data and stump height survey data from clearfall operations. The equation predicted total tree height from DBHOB, total log length and the small end diameter of the top log. Prediction accuracy for total tree height was evaluated both globally over the entire data space and locally within partitioned subspaces through benchmarking statistics. These statistics were better than that of the conventional height-diameter equations for P. radiata found in the literature, even when they incorporated stand age and the average height and diameter of dominant trees in the stand as predictors. So this equation when used with harvester data would outperform the conventional equations in tree height prediction. Tree and stand reconstructions of the harvested forest is the necessary first step to provide the essential link of harvester data to conventional inventory, remote sensing imagery and Li DAR data. The equations developed in this study will provide such a linkage for the most effective combined use of harvester data in predicting the attributes of individual trees, stands and forests, and product recovery for the management and planning of P. radiata plantations in New South Wales, Australia.展开更多
EuS is one of typical ferromagnetic semiconductor using as spin filter in spintronic devices,and the doped one could be a good spin injector.Herein,we fabricate a spin-functional tunnel junction by epitaxially growing...EuS is one of typical ferromagnetic semiconductor using as spin filter in spintronic devices,and the doped one could be a good spin injector.Herein,we fabricate a spin-functional tunnel junction by epitaxially growing the ferromagnetic EuS film on Nb-doped SrTiO3.The improvement of Curie temperature up to 35 K is associated with indirect exchange through additional charge carriers at the interface of EuS/Nb:STO junction.Its magnetic field controlled current-voltage curves indicate the large magnetoresistance(MR)effect in EuS barriers as a highly spin-polarized injector.The negative MR is up to 60%in 10-nm EuS/Nb:STO at 4 T and 30 K.The MR is enhanced with increasing thickness of EuS barrier.The large negative MR effect over a wide temperature range makes this junction into a potential candidate for spintronic devices.展开更多
The photoassociation dynamics of ultracold lithium atoms controlled by a cut-off pulse has been investigated theoretically by solving numerically the time-dependent Schr6dinger equation using the mapped Fourier grid m...The photoassociation dynamics of ultracold lithium atoms controlled by a cut-off pulse has been investigated theoretically by solving numerically the time-dependent Schr6dinger equation using the mapped Fourier grid method. The frequency components of the laser pulse close to the atomic resonance are partly cut off. Compared with the typical Gauss-type pulses, the cut-off pulse is helpful to suppress efficiently the weakly bound states and prepare the associated molecules in the lower vibrational states. Especially, the dependence of photoassociation probability on the cut-off position of the laser pulse is explored.展开更多
The community characteristics of natural secondary forests on the north slope of Changbai Mountain after selective cutting were investigated, and the dynamics of arborous species diversity during the restoration perio...The community characteristics of natural secondary forests on the north slope of Changbai Mountain after selective cutting were investigated, and the dynamics of arborous species diversity during the restoration period of 28 years were studied. The results showed that the arborous species richness (S) had little change and kept the range of 18-22 all along, the Simpson index (D) of the secondary layer and regeneration layer and whole stand had similar trends of change, but that of the canopy layer descended slowly in initial 15 years and had little change later, and the change of diversity index was not obvious and the Shannon-Wiener index (H? fluctuated in a very small scopes (H±10%).展开更多
Dalbergia sissoo Roxb. is one of the promising multipurpose tree species of South Asia. Most of the plantations of D. sissoo from seeds are facing severe threats due to the die-back disease, which ultimately causes de...Dalbergia sissoo Roxb. is one of the promising multipurpose tree species of South Asia. Most of the plantations of D. sissoo from seeds are facing severe threats due to the die-back disease, which ultimately causes death of this potential tree-species within a few months. Vegetative propagation could avoid the die-back disease. Thirty mother trees of different age-groups of D. sissoo were selected for evaluating the rooting behaviour of branch cuttings from D. sissoo as influenced by auxins （IAA or IBA at 100, 200, 500 mg·L^-1）, ages of mother trees （10, 4 and 2 years old） and different environment conditions, i.e., different mediums （soil and sand） or light conditions （in shade and open condition）. The results show that application of IAA and IBA induced more numbers of cuttings （collected from 10-year-old mother trees） to root compared to control. Branch cuttings of D. sissoo collected from 10-year-old mother trees and planted in soil bed in open conditions had 100.0% of cuttings to root in IAA （100 mg·L^-1） and IBA （200 mg·L^-1） treatments. Both rooting medium （Soil and sand） influenced significantly （p〈0.05） on rooting response of branch cuttings. Soil medium was found to achieve maximum no. of branch cuttings to root, compared to sand medium.展开更多
基金Project supported by the State Key Program for Basic Research of China(Grant No 2005CB724206)
文摘In this paper, we study the dynamics of the synchronous totally asymmetric simple exclusion process （TASEP） on lattices with two consecutive junctions in a multiple-input-multiple-output （MIMO） traffic system, which consists of m sub-chains for the input and the output, respectively. In the middle of the system, there are n （n 〈 m） sub-chains via two consecutive junctions linking m sub-chains of input and m sub-chains of output, respectively. This configuration is a type of complex geometry that is relevant to many biological processes as well as to vehicular traffic flow. We use a mean-field approach to calculate this typical geometry and obtain the theoretical results for stationary particle currents, density profiles, and a phase diagram. With the values of m and n synchronously increasing, the vertical phase boundary moves toward the right and the horizontal phase boundary moves toward the upside in the phase diagram. The boundary conditions of the system as well as the numbers of input and output determine the no-equilibrium stationary states, stationary-states phases, and phase boundaries. We use the results to compare with computer simulations and find that they are in very good agreement with each other.
文摘With an extensive range of distinctive features at nano meter-scale thicknesses,two-dimensional(2D)materials drawn the attention of the scientific community.Despite tremendous advancements in exploratory research on 2D materials,knowledge of 2D electrical transport and carrier dynamics still in its infancy.Thus,here we highlighted the electrical characteristics of 2D materials with electronic band structure,electronic transport,dielectric constant,carriers mobility.The atomic thinness of 2D materials makes substantially scaled field-effect transistors(FETs)with reduced short-channel effects conceivable,even though strong carrier mobility required for high performance,low-voltage device operations.We also discussed here about factors affecting 2D materials which easily enhanced the activity of those materials for various applications.Presently,Those 2D materials used in state-of-the-art electrical and optoelectronic devices because of the extensive nature of their electronic band structure.2D materials offer unprecedented freedom for the design of novel p-n junction device topologies in contrast to conventional bulk semiconductors.We also,describe the numerous 2D p-n junctions,such as homo junction and hetero junction including mixed dimensional junctions.Finally,we talked about the problems and potential for the future.
文摘We study theoretically the electrical shot noise properties of tunnel junctions between a normal metal and a superconductor with the mixture of singlet s-wave and chiral triplet p-wave pairing due to broken inversion symmetry. We investigate how the shot noise properties vary as the relative amplitude between the two parity components in the pairing potential is changed. It is demonstrated that some characteristics of the electrical shot noise properties of such tunnel junctions may depend sensitively on the relative amplitude between the two parity components in the pairing potential, and some significant changes may occur in the electrical shot noise properties when the relative amplitude between the two parity components is varied from the singlet s-wave pairing dominated regime to the chiral triplet p-wave pairing dominated regime. In the chiral triplet p-wave pairing dominated regime, the ratio of noise power to electric current is close to 2e both in the in-gap and in the out-gap region. In the singlet s-wave pairing dominated regime, the value of this ratio is close to 4e in the inner gap region but may reduce to about 2e in the outer gap region as the relative amplitude of the chiral triplet pairing component is increased. The variations of the differential shot noise with the bias voltage also exhibit some significantly different features in different regimes. Such different features can serve as useful diagnostic tools for the determination of the relative magnitude of the two parity components in the pairing potential.
文摘This paper studies two-dimensional analysis of the surface state effect on current gain for a 4H-SiC bipolar junction transistor （BJT）. Simulation results indicate the mechanism of current gain degradation, which is surface Fermi level pinning leading to a strong downward bending of the energy bands to form the channel of surface electron recombination current. The experimental results are well-matched with the simulation, which is modeled by exponential distributions of the interface state density replacing the single interface state trap. Furthermore, the simulation reveals that the oxide quality of the base emitter junction interface is very important for 4H-SiC BJT performance.
基金supported by the Jiangsu Provincial Public Institutions Program for Research Conditions and Building Capacity(No.BM2015019)the Foundation of Jiangsu Key Laboratory for the Research and Utilization of Plant Resources(Institute of Botany,Jiangsu Province and Chinese Academy of Sciences,No.JSPKLB201606)National Natural Science Foundation of China(No.31572155)
文摘The influence of low-vacuum helium cold plasma treatment on the rooting percentage,root growth and physiochemical properties of zoysiagrass stolon cuttings was studied.Zoysiagrass stolon cuttings were pre-treated with 0,100,200,300 and 400 W of cold plasma for 15 s.The cold plasma positively stimulated rooting and improved the root growth of the zoysiagrass stolon cuttings,and the 300 W treatment produced the best effect.The rooting percentage and root growth parameters,including the root length,total root surface area,total root volume,average root diameter,and root dry weight,significantly improved in response to the cold plasma treatment.In addition,the water uptake and relative conductivity of the stolon cuttings increased significantly in response to the cold plasma treatment.The results revealed that cold plasma-stimulated rooting and root growth appear to be a consequence of the improvement in permeability and water absorbing capacity of zoysiagrass stolon cuttings.The results of the present study will provide inspiration and support for the application of cold plasma in the vegetative propagation of plants.
基金the financial supports from the National Natural Science Foundation of China(No.:22002146)Taishan Scholars Foundation of Shandong province(No.:tsqn201909058).
文摘Establishing highly effective charge transfer channels in carbon nitride(g-C_(3)N_(4)) to enhance its photocatalytic activity is still a challenging issue.Herein,the delaminated 2D Ti_(3)C_(2) MXene nanosheets were employed to decorate the P-doped tubular g-C_(3)N_(4)(PTCN)for engineering 1D/2D Schottky heterojunction(PTCN/TC)through electrostatic self-assembly.The optimized PTCN/TC exhibited the highest hydrogen evolution rate(565 μmol h^(-1)g^(-1)),which was 4.3 and 2.0-fold higher than pristine bulk g-C_(3)N_(4) and PTCN,respectively.Such enhancement may be primarily attributed to the phosphorus heteroatom doped and unique structure of 1D/2D g-C_(3)N_(4)/Ti_(3)C_(2) Schottky heterojunction,enhancing the light-harvesting and charges’separation.One-dimensional pathway of g-C_(3)N_(4) tube and built-in electric field of interfacial Schottky effect can significantly facilitate the spatial separation of photogenerated charge carriers,and simultaneously inhibit their recombination via Schottky barrier.In this composite,metallic Ti_(3)C_(2) was served as electrons sink and photons collector.Moreover,ultrathin Ti_(3)C_(2) flake with exposed terminal metal sites as a co-catalyst exhibited higher photocatalytic reactivity in H2 evolution compared to carbon materials(such as reduced graphene oxide).This work not only proposed the mechanism of tubular g-C_(3)N_(4)/Ti_(3)C_(2) Schottky junction in photocatalysis,but also provided a feasible way to load ultrathin Ti_(3)C_(2) as a co-catalyst for designing highly efficient photocatalysts.
文摘In machining the particle reinforced aluminum based composite material with high Si content using the cobalt-cemented tungsten carbide micro cutting tools, diamond like carbon （DLC） films are deposited on cobalt-cemented tungsten carbide micro-drills with two-step pretreatment method. Characteristics of DLC coated tools are investigated in bias-enhanced HFCVD system with the optimized hot filament arrangement. The optimization deposition technology is obtained and the wear mechanism of cutting tools is analyzed. The drilling performance of DLC coated tools is verified by the experiments of cutting particle reinforced aluminum based composite material （Si 15% in volume） compared with uncoated ones. Experimental results show that the two-step pretreatment method is appropriate for complex shaped cemented carbide substrates and ensures the good adhesive strength between the diamond film and the substrate. The cutting performance of DLC coated tool is enhanced 10 times when machining the Si particle reinforced aluminum based metal matrix composite compared with that of uncoated ones under the same cutting conditions.
基金National Natural Science Foundation of China (Nos. 22371165, 22209098 and 21971143)111 Project (D20015)Opening Found of Hubei Three Gorges Laboratory (SC232001, SK213002)。
文摘Rational engineering of semiconductor photocatalysts for efficient hydrogen production is of great significance but still challenging,primarily due to the limitations in charge transfer kinetics.Herein,a fascinating plasmonic tandem heterojunction with the hc-CdS/Mo_(2)C@C heterostructure is aimfully prepared for effectively promoting the charge separation kinetics of the CdS photocatalyst via the synergistic strategy of phase junction,Schottky junction,and photothermal effect.The difference in atomic configuration between cubic-CdS (c-CdS) and hexagonal-CdS (h-CdS) leads to effective charge separation through a typical Ⅱ charge transfer mechanism,and plasmonic Schottky junction further extracts the electrons in the hc-CdS phase junction to realize gradient charge transfer.Besides,the photothermal effect of Mo_(2)C@C helps to expand the light absorption,accelerate charge transfer kinetics,and reduce the hydrogen evolution energy barrier.The carbon layer provides a fast channel for charge transfer and protects the photocatalyst from photocorrosion.As a result,the optimized hc-CMC photocatalyst exhibits a significantly high photocatalytic H_(2)production activity of 28.63 mmol/g/h and apparent quantum efficiency of 61.8%,surpassing most of the reported photocatalysts.This study provides a feasible strategy to enhance the charge transfer kinetics and photocatalytic activity of CdS by constructing plasmonic tandem heterogeneous junctions.
文摘We consider the effects of interface bound states on the electrical shot noise in tunnel junctions formed between normal metals and one-dimensional(1 D) or two-dimensional(2 D) Rashba semiconductors with proximity-induced s-wave pairing potential. We investigate how the shot noise properties vary as the interface bound state is evolved from a non-zero energy bound state to a zero-energy bound state. We show that in both 1 D and 2 D tunnel junctions, the ratio of the noise power to the charge current in the vicinity of zero bias voltage may be enhanced significantly due to the induction of the midgap interface bound state. But as the interface bound state evolves from a non-zero energy bound state to a zero-energy bound state, this ratio tends to vanish completely at zero bias voltage in 1 D tunnel junctions, while in 2 D tunnel junctions it decreases smoothly to the usual classical Schottky value for the normal state. Some other important aspects of the shot noise properties in such tunnel junctions are also clarified.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10474133 and 10674169）.
文摘A junction composed of ultrathin La0.9Ca0.1MnO3＋δ （LCMO） film and 1 wt.% Nb-doped SrTiO3 was fabricated and its magnetoresistance （MR） was studied and compared with LCMO film. It was found that the resistance of the junction has a similar dependence on magnetic field as that of the LCMO film： the curvature of R-H curves is upward above Curie temperature （Tc） and downward below TC. These behaviours strongly suggest that the rotation of ferromagnetic clusters in manganite also causes MR in the corresponding junction. This MR can be qualitatively understood by the change of the width of the barrier induced by the rotation of ferromagnetic clusters. These results suggest a possibility to obtain junctions with large low-field MR.
基金Project supported by the National Science Fund for Distinguished Young Scholars （Grant No 10125313）, the National Natural Science Foundation of China （Grant Nos 10573005 and 10273019）, and the Fund for Top Scholars of Guangdong Province （Grant No Q02114） and the Guangzhou Education Bureau and Guangzhou Science and Technology Bureau, China.
文摘Application of the first junction condition to a highly symmetric spacetime was investigated recently in Chin. Phys. Left. B 546 189 2006, where a partial differential equation arising from the connection of the Robertson-Walker and the Schwarzschild-de Sitter metrics was presented, but no solutions of the equation were provided. Here we provide a proof to the statement that there exist solutions of the equation. In addition, an example of the solution and some analyses associated with this issue are presented. We find that in connecting the two metrics, there are three conditions which should be satisfied. Of these conditions, one condition constrains the place where the two metrics can take the same value for a local system whose mass is provided which marks the boundary of the system, and the other two constrain the transformation form. In realizing the connection of the two metrics, the latter two conditions are required to be satisfied only at the boundary defined by the former condition.
文摘The magnetoresistance effect of a p-n junction under an electric field which is introduced by the gate voltage at room temperature is investigated by simulation. As auxiliary models, the Lombardi CVT model and carrier generation- recombination model are introduced into a drift-diffusion transport model and carrier continuity equations. All the equa- tions are discretized by the finite-difference method and the box integration method and then solved by Newton iteration. Taking advantage of those models and methods, an abrupt junction with uniform doping is studied systematically, and the magnetoresistance as a function of doping concentration, SiO2 thickness and geometrical size is also investigated. The simulation results show that the magnetoresistance （MR） can be controlled substantially by the gate and is dependent on the polarity of the magnetic field.
基金Project supported by the National Natural Science Foundation of China (Grant No 10404037)
文摘In order to consider quantum transport under the influence of an electron-electron （e-e） interaction in a mesoscopic conductor,the Boltzmann equation and Poisson equation are investigated jointly.The analytical expressions of the distribution function for the Boltzmann equation and the self-consistent average potential concerned with e-e interaction are obtained,and the dielectric function appearing in the self-consistent average potential is naturally generalized beyond the Thomas-Fermi approximation.Then we apply these results to the tunneling junctions of a metal-insulator-semiconductor （MIS） in which the electrons are accumulated near the interface of the semiconductor,and we find that the e-e interaction plays an important role in the transport procedure of this system. The electronic density,electric current as well as screening Coulombic potential in this case are studied,and we reveal the time and position dependence of these physical quantities explicitly affected by the e-e interaction.
基金supported by the National Natural Science Foundation of China (Grant Nos.52072272,52171145 and 22109120)the Zhejiang Provincial Natural Science Foundation of China (LQ21B030002)+1 种基金the Zhejiang Provincial Special Support Program for High-level Talents (2019R52042)the Key programs for Science and Technology Innovation of Wenzhou (ZG2022037)。
文摘The scarcity,high cost and susceptibility to CO of Platinum severely restrict its application in alkaline hydrogen oxidation reaction(HOR).Hybridizing Pt with other transition metals provides an effective strategy to modulate its catalytic HOR performance,but at the cost of mass activity due to the coverage of modifiers on Pt surface.Herein,we constructed dual junctions'Pt/nitrogen-doped carbon(Pt/NC)andδ-MoC/NC to modify electronic structure of Pt via interfacial electron transfer to acquire Pt-MoC@NC catalyst with electron-deficient Pt nanoparticles,simultaneously endowing it with high mass activity and durability of alkaline HOR.Moreover,the unique structure of Pt-MoC@NC endows Pt with a high COtolerance at 1,000 ppm CO/H_(2),a quality that commercial Pt-C catalyst lacks.The theoretical calculations not only confirm the diffusion of electrons from Pt/NC to Mo C/NC could occur,but also demonstrate the negative shift of Pt d-band center for the optimized binding energies of*H,*OH and CO.
文摘This paper proposes a thermal analytical model of current gain for bipolar junction transistor-bipolar static induction transistor （BJT-BSIT） compound device in the low current operation. It also proposes a best thermal compensating factor to the compound device that indicates the relationship between the thermal variation rate of current gain and device structure. This is important for the design of compound device to be optimized. Finally, the analytical model is found to be in good agreement with numerical simulation and experimental results. The test results demonstrate that thermal variation rate of current gain is below 10% in 25 ℃-85 ℃ and 20% in -55 ℃-25 ℃.
基金supported by the Forestry Corporation of New South Wales
文摘With their widespread utilization, cut-to-length harvesters have become a major source of ‘‘big data’’ for forest management as they constantly capture, and provide a daily flow of, information on log production and assortment over large operational areas. Harvester data afford the calculation of the total log length between the stump and the last cut but not the total height of trees. They also contain the length and end diameters of individual logs but not always the diameter at breast height overbark（DBHOB） of harvested stems largely because of time lapse, operating and processing issues and other system deficiencies. Even when DBHOB is extracted from harvester data, errors and/or bias of the machine measurements due to the variation in the stump height of harvested stems from that specified for the harvester head prior to harvesting and diameter measurement errors may need to be corrected. This study developed（1） a system of equations for estimating DBHOB of trees from diameter overbark（DOB） measured by a harvester head at any height up to 3 m above ground level and（2） an equation to predict the total height of harvested stems in P. radiata plantations from harvester data. To generate the data required for this purpose, cut-to-length simulations of more than 3000 trees with detailed taper measurements were carried out in the computer using the cutting patterns extracted from the harvester data and stump height survey data from clearfall operations. The equation predicted total tree height from DBHOB, total log length and the small end diameter of the top log. Prediction accuracy for total tree height was evaluated both globally over the entire data space and locally within partitioned subspaces through benchmarking statistics. These statistics were better than that of the conventional height-diameter equations for P. radiata found in the literature, even when they incorporated stand age and the average height and diameter of dominant trees in the stand as predictors. So this equation when used with harvester data would outperform the conventional equations in tree height prediction. Tree and stand reconstructions of the harvested forest is the necessary first step to provide the essential link of harvester data to conventional inventory, remote sensing imagery and Li DAR data. The equations developed in this study will provide such a linkage for the most effective combined use of harvester data in predicting the attributes of individual trees, stands and forests, and product recovery for the management and planning of P. radiata plantations in New South Wales, Australia.
基金Project supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB28000000 and XDB07000000)the National Key Research and Development Program of China(Grant No.2016YFA0300600)the Fund from the Beijing Municipal Science&Technology Commission(Grant No.Z191100007219012).
文摘EuS is one of typical ferromagnetic semiconductor using as spin filter in spintronic devices,and the doped one could be a good spin injector.Herein,we fabricate a spin-functional tunnel junction by epitaxially growing the ferromagnetic EuS film on Nb-doped SrTiO3.The improvement of Curie temperature up to 35 K is associated with indirect exchange through additional charge carriers at the interface of EuS/Nb:STO junction.Its magnetic field controlled current-voltage curves indicate the large magnetoresistance(MR)effect in EuS barriers as a highly spin-polarized injector.The negative MR is up to 60%in 10-nm EuS/Nb:STO at 4 T and 30 K.The MR is enhanced with increasing thickness of EuS barrier.The large negative MR effect over a wide temperature range makes this junction into a potential candidate for spintronic devices.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10974024)the SRFDP, China (Grant No. 20090041110025)
文摘The photoassociation dynamics of ultracold lithium atoms controlled by a cut-off pulse has been investigated theoretically by solving numerically the time-dependent Schr6dinger equation using the mapped Fourier grid method. The frequency components of the laser pulse close to the atomic resonance are partly cut off. Compared with the typical Gauss-type pulses, the cut-off pulse is helpful to suppress efficiently the weakly bound states and prepare the associated molecules in the lower vibrational states. Especially, the dependence of photoassociation probability on the cut-off position of the laser pulse is explored.
基金This research was supported by Institute of Shenyang Applied Ecology CAS (SCXMS0101),National Key Technologies R&D Program (NKTRDP. 2002BA516A20) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, Ministry of Education
文摘The community characteristics of natural secondary forests on the north slope of Changbai Mountain after selective cutting were investigated, and the dynamics of arborous species diversity during the restoration period of 28 years were studied. The results showed that the arborous species richness (S) had little change and kept the range of 18-22 all along, the Simpson index (D) of the secondary layer and regeneration layer and whole stand had similar trends of change, but that of the canopy layer descended slowly in initial 15 years and had little change later, and the change of diversity index was not obvious and the Shannon-Wiener index (H? fluctuated in a very small scopes (H±10%).
基金supported by Indian Council ofForestry Research and Education (ICFRE), Dehradun, 248 006, Uttarakhand, India
文摘Dalbergia sissoo Roxb. is one of the promising multipurpose tree species of South Asia. Most of the plantations of D. sissoo from seeds are facing severe threats due to the die-back disease, which ultimately causes death of this potential tree-species within a few months. Vegetative propagation could avoid the die-back disease. Thirty mother trees of different age-groups of D. sissoo were selected for evaluating the rooting behaviour of branch cuttings from D. sissoo as influenced by auxins （IAA or IBA at 100, 200, 500 mg·L^-1）, ages of mother trees （10, 4 and 2 years old） and different environment conditions, i.e., different mediums （soil and sand） or light conditions （in shade and open condition）. The results show that application of IAA and IBA induced more numbers of cuttings （collected from 10-year-old mother trees） to root compared to control. Branch cuttings of D. sissoo collected from 10-year-old mother trees and planted in soil bed in open conditions had 100.0% of cuttings to root in IAA （100 mg·L^-1） and IBA （200 mg·L^-1） treatments. Both rooting medium （Soil and sand） influenced significantly （p〈0.05） on rooting response of branch cuttings. Soil medium was found to achieve maximum no. of branch cuttings to root, compared to sand medium.
