The effects of auxin polar transport inhibitors, 9-hydroxy-fluorene-9-carboxylic acid (HFCA); 2, 3, 5-triiodobenzoic acid (TIBA) and trans-cinnamic acid (CA)on leaf pattern formation were investigated with shoots form...The effects of auxin polar transport inhibitors, 9-hydroxy-fluorene-9-carboxylic acid (HFCA); 2, 3, 5-triiodobenzoic acid (TIBA) and trans-cinnamic acid (CA)on leaf pattern formation were investigated with shoots formed from cultured leaf explants of tobacco and cultured pedicel explants of Orychophragmus violaceus, and the seedlings of tobacco and Brassica chinensis. Although the effective concentration varies with the inhibitors used, all of the inhibitors induced the formation of trumpet-shaped and/or fused leaves. The frequency of trumpet-shaped leaf formation was related to the concentration of inhibitors in the medium.Histological observation of tobacco seedlings showed that there was only one main vascular bundle and several minor vascular bundles in normal leaves of the control, but there were several vascular bundles of more or less the same size in the trumpet-shaped leaves of treated ones.These results indicated that auxin polar transport played an important role on bilateral symmetry of leaf growth.展开更多
Polar auxin transport (PAT) is critical in plant growth and development, especially polar differentiation and pattern formation. Lots of studies have been performed in dicots while relative less in monocots. Using two...Polar auxin transport (PAT) is critical in plant growth and development, especially polar differentiation and pattern formation. Lots of studies have been performed in dicots while relative less in monocots. Using two kinds of PAT inhibitors, 2, 3, 5-triiodobenzoic acid (TIBA) and 9-hydroxyfluorene-9-carboxylic acid (HFCA), it was shown that PAT is important for rice (Oryza sativa L. cv. Zhonghua 11) root development, including elongation of the primary roots, initiation and elongation of lateral roots, and formation of adventitious roots. Inhibition of PAT resulted in the shortened primary roots, less and shortened lateral and adventitious roots. Exogenously supplemented NAA can partially rescue the formation of adventitious roots but not lateral roots, while low concentration of NAA (0.1 mumol/L) could not rescue either of them, suggesting the possible different mechanisms of lateral and adventitious root initiations. Treatment of 30 mumol/L TIBA did not completely inhibit the initiation of lateral roots, and survival capacities of which were demonstrated through cross section experiments revealing the presence of primordial of lateral roots at different stages. Further studies through localized application of PAT inhibitors indicated that auxin flow, transported from coleoptiles to the base, is not only responsible for the auxin contents in stem nodes but also critical for initiation and elongation of adventitious roots.展开更多
We develop a Monte Carlo （MC） tool incorporated with the three-subband approximation model to investigate the in-plane spln-polarized transport in GaAs/GaAlAs quantum well. Using the tool, the effects of the electro...We develop a Monte Carlo （MC） tool incorporated with the three-subband approximation model to investigate the in-plane spln-polarized transport in GaAs/GaAlAs quantum well. Using the tool, the effects of the electron occupation of higher subbands and the intersuhband scattering on the spin dephasing have been studied. Compared with the corresponding results of the simple one-snbband approximation model, the spin dephasing length is reduced four times under 0.125 kV/cm of driving electric field at 300K by the MC tool incorporated with the three-subband approximation model, indicating that the three-subbarld approximation model predicts significantly shorter spin dephasing length with temperature increasing. Our simulation results suggest that the effects of the electron occupation of higher subbands and the intersubband scattering on the spln-dependent transport of GaAs 2-dhuensional electron gas need to be considered when the driving electric field exceeds the moderate value and the lattice temperature is above 100K. The simulation by using the MC tool incorporated with the three-subband approximation model also indicates that, under a eertain driving electric field and lattice temperature, larger channel widths cause spins to be depolarized faster. Ranges of the three components of the spins are different for three different injected spin polarizations due to the anisotropy of spin-orbit interaction.展开更多
The spin-polarized linear conductance spectrum and current–voltage characteristics in a four-quantum-dot ring embodied into Aharonov–Bohm （AB） interferometer are investigated theoretically by considering a local R...The spin-polarized linear conductance spectrum and current–voltage characteristics in a four-quantum-dot ring embodied into Aharonov–Bohm （AB） interferometer are investigated theoretically by considering a local Rashba spin–orbit interaction. It shows that the spin-polarized linear conductance and the corresponding spin polarization are each a function of magnetic flux phase at zero bias voltage with a period of 2π, and that Hubbard U cannot influence the electron transport properties in this case. When adjusting appropriately the structural parameter of inter-dot coupling and dot-lead coupling strength, the electronic spin polarization can reach a maximum value. Furthermore, by adjusting the bias voltages applied to the leads, the spin-up and spin-down currents move in opposite directions and pure spin current exists in the configuration space in appropriate situations. Based on the numerical results, such a model can be applied to the design of a spin filter device.展开更多
The influence of electron-phonon （EP） scattering on spin polarization of current output from a mesoscopic ring with Rashba spin-orbit （SO） interaction is numerically investigated. There are three leads connecting ...The influence of electron-phonon （EP） scattering on spin polarization of current output from a mesoscopic ring with Rashba spin-orbit （SO） interaction is numerically investigated. There are three leads connecting to the ring at different positionsl unpolarized current is injected to one of them, and the other two are output channels with different bias voltages. The spin polarization of current in the outgoing leads shows oscillations as a function of EP coupling strength owing to the quantum interference of EP states in the ring region. As temperature increases, the oscillations are evidently suppressed, implying decoherence of the EP states. The simulation shows that the magnitude of polarized current is sensitive to the location of the lead. The polarized current depends on the connecting position of the lead in a complicated way due to the spin-sensitive quantum interference effects caused by different phases accumulated by transmitting electrons with opposite spin states along different paths.展开更多
Using the Keldysh nonequilibrium Green function and equation-of-motion technique, this paper investigates the spin-polarized transport properties of the T-shaped double quantum dots （DQD） coupled to two ferromagneti...Using the Keldysh nonequilibrium Green function and equation-of-motion technique, this paper investigates the spin-polarized transport properties of the T-shaped double quantum dots （DQD） coupled to two ferromagnetic leads. There are both Fano effect and Kondo effect in the system, and due to their mutual interaction, the density of states, the current, and the differential conductance of the system depend sensitively on the spin-polarized strength. Thus the obtained results show that this system is provided with excellent spin filtering property, which indicates that this system may be a candidate for spin valve transistors in the spintronics.展开更多
Influence of spin–orbit coupling on spin-polarized electronic transport in magnetic semiconductor nanowires with nanosized sharp domain walls is investigated theoretically.It is shown that the Rashba spin–orbit coup...Influence of spin–orbit coupling on spin-polarized electronic transport in magnetic semiconductor nanowires with nanosized sharp domain walls is investigated theoretically.It is shown that the Rashba spin–orbit coupling can enhance significantly the spin-flip scattering of charge carriers from a nanosized sharp domain wall whose extension is much smaller than the carrier＇s Fermi wavelength.When there are more than one domain wall presented in a magnetic semiconductor nanowire,not only the spin-flip scattering of charge carriers from the domain walls but the quantum interference of charge carriers in the intermediate domain regions between neighboring domain walls may play important roles on spin-polarized electronic transport,and in such cases the influences of the Rashba spin–orbit coupling will depend sensitively both on the domain walls＇ width and the domain walls＇ separation.展开更多
Study on the role of quereentin in polar auxin transportation. Arabidopsis was cultured on medium supplemented with quereetin to observe the growth of hypoeotyls, ^14C-IAA transport assays were conducted to measure th...Study on the role of quereentin in polar auxin transportation. Arabidopsis was cultured on medium supplemented with quereetin to observe the growth of hypoeotyls, ^14C-IAA transport assays were conducted to measure the auxin transport activity. The results showed that Arabidopsis mutant auxl which had been deficient in auxin influx transportion obviously recovered the ability after eultured on the medium with quercetin. The polar auxin transport was promoted by the addition of quereetin. These results indicated that quereetin could promote polar auxin transport in vivo.展开更多
A generalized finite element formulation is proposed for the study of the spin-dependent ballistic transport of electron through the two-dimensional quantum structures with Rashba spin-orbit interactions （SOI）. The ...A generalized finite element formulation is proposed for the study of the spin-dependent ballistic transport of electron through the two-dimensional quantum structures with Rashba spin-orbit interactions （SOI）. The transmission coefficient, conductance, the total and local polarization are numerically calculated and discussed as the Rashba eoefficient, the geometric sizes, and incident energy are changed in the T-shaped devices. Some interesting features are found in the proper parameter regime. The polarization has an enhancement as the Rashba coefficient becomes stronger. The polarization valley is rigid in the regime of the conductance plateaus since the local interference among the polarized multi-wave modes. The Rashba interactions coupling to geometry in sizes could form the structure-induced Fano-Rashba resonance. In the wider stub, the localized spin lattice of electron could be produced. The conductance plateaus correspond to weak polarizations. Strong polarizations appear when the stub sizes, incident energy, and the Rashba coupling coefficient are matched. The resonances are formed in a wide Fermi energy segment easily.展开更多
We investigate theoretically the electron transport for a two-level quantum channel （wire） with Rashba spinorbit coupling under the irradiation of a longitudinally-polarized external laser field at low temperatures....We investigate theoretically the electron transport for a two-level quantum channel （wire） with Rashba spinorbit coupling under the irradiation of a longitudinally-polarized external laser field at low temperatures. Using the method of equation of motion for Keldysh nonequilibrium Green function, we examine the time-averaged spin polarized conductance for the system with photon polarization parallel to the wire direction. By analytical analysis and a few numerical examples, the interplay effects of the external laser field and the Rashba spin-orbit coupling on the spinpolarized conductance for the system are demonstrated and discussed. It is found that the longitudinally-polarized laser field can adjust the spin polarization rate and produce some photon sideband resonances of the conductance for the system.展开更多
Electronic transport through a vibrating double quantum dot （DQD） in contact with noncollinear ferromagnetic （FM） leads is investigated. The state transition between the two dots of the DQD is excited by an AC mic...Electronic transport through a vibrating double quantum dot （DQD） in contact with noncollinear ferromagnetic （FM） leads is investigated. The state transition between the two dots of the DQD is excited by an AC microwave driving field. The corresponding currents and differential conductance are calculated in the Coulomb blockade regime by means of the Born-Markov master equation. It is shown that the interplay between electrons and phonons gives rise to phonon-assisted tunneling resonances and Franck-Condon blockade under certain conditions. In noncollinear magnetic configurations, spin-blockade effects are also observed, and the angle of polarization has some influence on the transport characteristics.展开更多
Nonequilibrium electronic transports through a system hosting three quantum dots hybridized with superconductors are investigated. By tuning the relative positions of the dot levels, we illustrate the existence of Maj...Nonequilibrium electronic transports through a system hosting three quantum dots hybridized with superconductors are investigated. By tuning the relative positions of the dot levels, we illustrate the existence of Majorana fermions and show that the Majorana feimions will either survive separately on single dots or distribute themselves among different dots with tunable probabilities. As a result, different physical mechanisms appear, including local Andreev reflection（LAR）,cross Andreev reflection（CAR）, and cross resonant tunneling（CRT）. The resulting characteristics may be used to reveal the unique properties of Majorana fermions. In addition, we discuss the spin-polarized transports and find a pure spin current and a spin filter effect due to the joint effect of CRT and CAR, which is important for designing spintronic devices.展开更多
文摘The effects of auxin polar transport inhibitors, 9-hydroxy-fluorene-9-carboxylic acid (HFCA); 2, 3, 5-triiodobenzoic acid (TIBA) and trans-cinnamic acid (CA)on leaf pattern formation were investigated with shoots formed from cultured leaf explants of tobacco and cultured pedicel explants of Orychophragmus violaceus, and the seedlings of tobacco and Brassica chinensis. Although the effective concentration varies with the inhibitors used, all of the inhibitors induced the formation of trumpet-shaped and/or fused leaves. The frequency of trumpet-shaped leaf formation was related to the concentration of inhibitors in the medium.Histological observation of tobacco seedlings showed that there was only one main vascular bundle and several minor vascular bundles in normal leaves of the control, but there were several vascular bundles of more or less the same size in the trumpet-shaped leaves of treated ones.These results indicated that auxin polar transport played an important role on bilateral symmetry of leaf growth.
文摘Polar auxin transport (PAT) is critical in plant growth and development, especially polar differentiation and pattern formation. Lots of studies have been performed in dicots while relative less in monocots. Using two kinds of PAT inhibitors, 2, 3, 5-triiodobenzoic acid (TIBA) and 9-hydroxyfluorene-9-carboxylic acid (HFCA), it was shown that PAT is important for rice (Oryza sativa L. cv. Zhonghua 11) root development, including elongation of the primary roots, initiation and elongation of lateral roots, and formation of adventitious roots. Inhibition of PAT resulted in the shortened primary roots, less and shortened lateral and adventitious roots. Exogenously supplemented NAA can partially rescue the formation of adventitious roots but not lateral roots, while low concentration of NAA (0.1 mumol/L) could not rescue either of them, suggesting the possible different mechanisms of lateral and adventitious root initiations. Treatment of 30 mumol/L TIBA did not completely inhibit the initiation of lateral roots, and survival capacities of which were demonstrated through cross section experiments revealing the presence of primordial of lateral roots at different stages. Further studies through localized application of PAT inhibitors indicated that auxin flow, transported from coleoptiles to the base, is not only responsible for the auxin contents in stem nodes but also critical for initiation and elongation of adventitious roots.
基金Project supported in part by the National Natural Science Foundation of China （Grant Nos 90307006 and 10234010）, and the Research Fund for the Datoral Program of Higher Education of China （Grant Nos 20040001026 and 20020001018）.
文摘We develop a Monte Carlo （MC） tool incorporated with the three-subband approximation model to investigate the in-plane spln-polarized transport in GaAs/GaAlAs quantum well. Using the tool, the effects of the electron occupation of higher subbands and the intersuhband scattering on the spin dephasing have been studied. Compared with the corresponding results of the simple one-snbband approximation model, the spin dephasing length is reduced four times under 0.125 kV/cm of driving electric field at 300K by the MC tool incorporated with the three-subband approximation model, indicating that the three-subbarld approximation model predicts significantly shorter spin dephasing length with temperature increasing. Our simulation results suggest that the effects of the electron occupation of higher subbands and the intersubband scattering on the spln-dependent transport of GaAs 2-dhuensional electron gas need to be considered when the driving electric field exceeds the moderate value and the lattice temperature is above 100K. The simulation by using the MC tool incorporated with the three-subband approximation model also indicates that, under a eertain driving electric field and lattice temperature, larger channel widths cause spins to be depolarized faster. Ranges of the three components of the spins are different for three different injected spin polarizations due to the anisotropy of spin-orbit interaction.
基金Project supported by the Natural Science Foundation of Liaoning Province, China (Grant No. 201202085)the National Natural Science Foundation of China(Grant No. 11004138)+1 种基金the Excellent Young Scientists Fund of Liaoning Provence, China (Grant No. LJQ2011020)the Young Scientists Fund of Shenyang Ligong University (Grant No. 2011QN-04-11)
文摘The spin-polarized linear conductance spectrum and current–voltage characteristics in a four-quantum-dot ring embodied into Aharonov–Bohm （AB） interferometer are investigated theoretically by considering a local Rashba spin–orbit interaction. It shows that the spin-polarized linear conductance and the corresponding spin polarization are each a function of magnetic flux phase at zero bias voltage with a period of 2π, and that Hubbard U cannot influence the electron transport properties in this case. When adjusting appropriately the structural parameter of inter-dot coupling and dot-lead coupling strength, the electronic spin polarization can reach a maximum value. Furthermore, by adjusting the bias voltages applied to the leads, the spin-up and spin-down currents move in opposite directions and pure spin current exists in the configuration space in appropriate situations. Based on the numerical results, such a model can be applied to the design of a spin filter device.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10474033 and 60676056)the State Key Projects of Basic Research of China (Grant Nos 2006CB0L1000 and 2005CB623605)
文摘The influence of electron-phonon （EP） scattering on spin polarization of current output from a mesoscopic ring with Rashba spin-orbit （SO） interaction is numerically investigated. There are three leads connecting to the ring at different positionsl unpolarized current is injected to one of them, and the other two are output channels with different bias voltages. The spin polarization of current in the outgoing leads shows oscillations as a function of EP coupling strength owing to the quantum interference of EP states in the ring region. As temperature increases, the oscillations are evidently suppressed, implying decoherence of the EP states. The simulation shows that the magnitude of polarized current is sensitive to the location of the lead. The polarized current depends on the connecting position of the lead in a complicated way due to the spin-sensitive quantum interference effects caused by different phases accumulated by transmitting electrons with opposite spin states along different paths.
基金Project supported by the Scientific Research Foundation of Sichuan Provincial Education,China (Grant No 2006A069)Sichuan Provincial Research Foundation for Basic Research,China (Grant No 2006J13-155)
文摘Using the Keldysh nonequilibrium Green function and equation-of-motion technique, this paper investigates the spin-polarized transport properties of the T-shaped double quantum dots （DQD） coupled to two ferromagnetic leads. There are both Fano effect and Kondo effect in the system, and due to their mutual interaction, the density of states, the current, and the differential conductance of the system depend sensitively on the spin-polarized strength. Thus the obtained results show that this system is provided with excellent spin filtering property, which indicates that this system may be a candidate for spin valve transistors in the spintronics.
文摘Influence of spin–orbit coupling on spin-polarized electronic transport in magnetic semiconductor nanowires with nanosized sharp domain walls is investigated theoretically.It is shown that the Rashba spin–orbit coupling can enhance significantly the spin-flip scattering of charge carriers from a nanosized sharp domain wall whose extension is much smaller than the carrier＇s Fermi wavelength.When there are more than one domain wall presented in a magnetic semiconductor nanowire,not only the spin-flip scattering of charge carriers from the domain walls but the quantum interference of charge carriers in the intermediate domain regions between neighboring domain walls may play important roles on spin-polarized electronic transport,and in such cases the influences of the Rashba spin–orbit coupling will depend sensitively both on the domain walls＇ width and the domain walls＇ separation.
基金Key Project of Conditions Platform of National Science and Technology (2005DKA21002-15)~~
文摘Study on the role of quereentin in polar auxin transportation. Arabidopsis was cultured on medium supplemented with quereetin to observe the growth of hypoeotyls, ^14C-IAA transport assays were conducted to measure the auxin transport activity. The results showed that Arabidopsis mutant auxl which had been deficient in auxin influx transportion obviously recovered the ability after eultured on the medium with quercetin. The polar auxin transport was promoted by the addition of quereetin. These results indicated that quereetin could promote polar auxin transport in vivo.
基金Supported by the National Science Foundation of China under Grant No.2006CB921605
文摘A generalized finite element formulation is proposed for the study of the spin-dependent ballistic transport of electron through the two-dimensional quantum structures with Rashba spin-orbit interactions （SOI）. The transmission coefficient, conductance, the total and local polarization are numerically calculated and discussed as the Rashba eoefficient, the geometric sizes, and incident energy are changed in the T-shaped devices. Some interesting features are found in the proper parameter regime. The polarization has an enhancement as the Rashba coefficient becomes stronger. The polarization valley is rigid in the regime of the conductance plateaus since the local interference among the polarized multi-wave modes. The Rashba interactions coupling to geometry in sizes could form the structure-induced Fano-Rashba resonance. In the wider stub, the localized spin lattice of electron could be produced. The conductance plateaus correspond to weak polarizations. Strong polarizations appear when the stub sizes, incident energy, and the Rashba coupling coefficient are matched. The resonances are formed in a wide Fermi energy segment easily.
基金Project supported by the National Natural Science Foundation of China （Grant No 10574042）, and the Hunan Provincial Natural Science Foundation of China （Grant No 06JJ2097）.
文摘We investigate theoretically the electron transport for a two-level quantum channel （wire） with Rashba spinorbit coupling under the irradiation of a longitudinally-polarized external laser field at low temperatures. Using the method of equation of motion for Keldysh nonequilibrium Green function, we examine the time-averaged spin polarized conductance for the system with photon polarization parallel to the wire direction. By analytical analysis and a few numerical examples, the interplay effects of the external laser field and the Rashba spin-orbit coupling on the spinpolarized conductance for the system are demonstrated and discussed. It is found that the longitudinally-polarized laser field can adjust the spin polarization rate and produce some photon sideband resonances of the conductance for the system.
基金Project supported by the National Natural Science Foundation of China(Grant No.61275059)
文摘Electronic transport through a vibrating double quantum dot （DQD） in contact with noncollinear ferromagnetic （FM） leads is investigated. The state transition between the two dots of the DQD is excited by an AC microwave driving field. The corresponding currents and differential conductance are calculated in the Coulomb blockade regime by means of the Born-Markov master equation. It is shown that the interplay between electrons and phonons gives rise to phonon-assisted tunneling resonances and Franck-Condon blockade under certain conditions. In noncollinear magnetic configurations, spin-blockade effects are also observed, and the angle of polarization has some influence on the transport characteristics.
基金supported by the New Century Excellent Talents in University of China(Grant No.NCET-10-0090)the National Natural Science Foundation of China(Grant Nos.11474106,11174088,and 11274124)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in University of China(Grant No.IRT1243)the Natural Science Foundation of Guangdong Province,China(Grant No.S2012010010681)
文摘Nonequilibrium electronic transports through a system hosting three quantum dots hybridized with superconductors are investigated. By tuning the relative positions of the dot levels, we illustrate the existence of Majorana fermions and show that the Majorana feimions will either survive separately on single dots or distribute themselves among different dots with tunable probabilities. As a result, different physical mechanisms appear, including local Andreev reflection（LAR）,cross Andreev reflection（CAR）, and cross resonant tunneling（CRT）. The resulting characteristics may be used to reveal the unique properties of Majorana fermions. In addition, we discuss the spin-polarized transports and find a pure spin current and a spin filter effect due to the joint effect of CRT and CAR, which is important for designing spintronic devices.
