The high-affinity K＋ （HAK） transporter gene family is the largest family in plant that functions as potassium transporter and is important for various aspects of plant life. In the present study, we identified 27 m...The high-affinity K＋ （HAK） transporter gene family is the largest family in plant that functions as potassium transporter and is important for various aspects of plant life. In the present study, we identified 27 members of this family in rice genome. The phylogenetic tree divided the land plant HAK transporter proteins into 6 distinct groups. Although the main characteristic of this family was established before the origin of seed plants, they also showed some differences between the members of non-seed and seed plants. The HAK genes in rice were found to have expanded in lineage-specific manner after the split of monocots and dicots, and both segmental duplication events and tandem duplication events contributed to the expansion of this family. Functional divergence analysis for this family provided statistical evidence for shifted evolutionary rate after gene duplication. Further analysis indicated that both point mutant with positive selection and gene conversion events contributed to the evolution of this family in rice.展开更多
We propose a new flame index for the transported probability density function(PDF) method. The flame index uses mixing flux projections of Lagrangian particles on mixture fraction and progress variable directions as t...We propose a new flame index for the transported probability density function(PDF) method. The flame index uses mixing flux projections of Lagrangian particles on mixture fraction and progress variable directions as the metrics to identify the combustion mode, with the Burke-Schumann solution as a reference. A priori validation of the flame index is conducted with a series of constructed turbulent partially premixed reactors. It indicates that the proposed flame index is able to identify the combustion mode based on the subgrid mixing information. The flame index is then applied the large eddy simulation/PDF datasets of turbulent partially premixed jet flames. Results show that the flame index separate different combustion modes and extinction correctly. The proposed flame index provides a promising tool to analyze and model the partially premixed flames adaptively.展开更多
In present paper, the non-equilibrium Green function(NEGF) method along with the density functional theory(DFT) are used to investigate the effect of width on transport and electronic properties of armchair graphyne(...In present paper, the non-equilibrium Green function(NEGF) method along with the density functional theory(DFT) are used to investigate the effect of width on transport and electronic properties of armchair graphyne(γ-graphyne) nanoribbons. The results show that all the studied nanoribbons are semiconductor and their band gaps decrease as the widths of nanoribbons increase, which will result in increasing current at a certain voltage. Also our results show the promising application of armchair graphyne nanoribbons in nano-electrical devices.展开更多
In the present work, firstly, a first-principles study of the structural, electronic, and electron transport properties of the HgxMg1-xTe（HMT） ternary compound is performed using the ABINIT package and the results a...In the present work, firstly, a first-principles study of the structural, electronic, and electron transport properties of the HgxMg1-xTe（HMT） ternary compound is performed using the ABINIT package and the results are compared with Cd0.9Zn0.1 Te（CZT） as a current room-temperature photodetector. Next, the response functions of Hg0.6Mg0.4Te and Cd0.9Zn0.1Te under electromagnetic irradiation with 0.05 Me V, 0.2 MeV, 0.661 MeV and 1.33 MeV energies are simulated by using the MCNP code. According to these simulations, the Hg0.6Mg0.4Te ternary compound is suggested as a good semiconductor photodetector for use at room temperature.展开更多
Electroosmotic water vapor transport (WVT) across very thin, flexible, functionalized conducting polymer (CP) microporous (μP) membranes at a very high rate is reported. Both passive and active (6 VDC applied) WVT ar...Electroosmotic water vapor transport (WVT) across very thin, flexible, functionalized conducting polymer (CP) microporous (μP) membranes at a very high rate is reported. Both passive and active (6 VDC applied) WVT are reported, the latter for the first time ever. WVT occurs with concomitant, effective blocking of chemical warfare (CW) agents, again demonstrated for the first time ever. Initial active liquid||membrane||liquid interface studies demonstrated WVT rates of >1.7 × 10-5g .mm-2s-1, >3 × the highest prior reported values of 5 × 10-6g.mm-2s-1. Subsequent vapor||membrane|| vapor interface studies using industry-standard methods (including ASTM E96B Upright Cup (“WVT”), ASTM F2298 (“Dynamic Moisture Permeation Cell”) and ASTM F1868 (“Sweating Guard Hotplate”) were done at independent, external labs for independent corroboration. These yielded, e.g., WVT values of2564.4 g.m2.d-1 (passive) and3706.7 g.m2d-1 (active), to be compared with the highest (passive) value ever reported previously,984.8 g.m2.d-1 for a μP-Nylon membrane. More than 15 different membrane configurations, porosities and types were studied, including membranes with CP + organophosphate hydrolase (OPH), an enzyme reactive to CW agents. Efficient blocking of the actual CW agents GB, HD, VX is also reported, using the TOP-8-2-501standard. Membranes also passed all Industry-standard durability tests, e.g. ASTM D2261 (Tearing), ASTM D5034 (Breaking), ASTM D3886 (Abrasion), ASTM F392 (Gelbo Flex). Incorporation into smart soldiers’ garments was demonstrated;power consumption was -2. Mechanisms of enhanced WVT and CW agent blocking in the membranes are discussed.展开更多
Background： Cinnamicaldehyde（CA） is a key flavor compound in cinnamon essential oil possessing various bioactivities. Tight junction（TJ） proteins are vital for the maintenance of intestinal epithelial barrier fun...Background： Cinnamicaldehyde（CA） is a key flavor compound in cinnamon essential oil possessing various bioactivities. Tight junction（TJ） proteins are vital for the maintenance of intestinal epithelial barrier function,transport, absorption and utilization of dietary amino acids and other nutrients. In this study, we tested the hypothesis that CA may regulate the expression of TJ proteins and amino acid transporters in intestinal porcine epithelial cells（IPEC-1） isolated from neonatal pigs.Results： Compared with the control, cells incubated with 25 μmol/L CA had increased transepithelial electrical resistance（TEER） and decreased paracellular intestinal permeability. The beneficial effect of CA on mucosal barrier function was associated with enhanced protein abundance for claudin-4, zonula occludens（ZO）-1, ZO-2, and ZO-3. Immunofluorescence staining showed that 25 μmol/L CA promoted the localization of claudin-1 and claudin-3 to the plasma membrane without affecting the localization of other TJ proteins, including claudin-4, occludin,ZO-1, ZO-2, and ZO-3, compared with the control cells. Moreover, protein abundances for rBAT, xCT and LAT2 in IPEC-1 cells were enhanced by 25 μmol/L CA, while that for EAAT3 was not affected.Conclusions： CA improves intestinal mucosal barrier function by regulating the distribution of claudin-1 and claudin-3 in enterocytes, as well as enhancing protein abundance for amino acid transporters rBAT, xCT and LAT2 in enterocytes. Supplementation with CA may provide an effective nutritional strategy to improve intestinal integrity and amino acid transport and absorption in piglets.展开更多
Exploring, designing, and synthesizing novel organic field-effect transistor （OFET） materials have kept an important and hot issue in organic electronics. In the current work, the charge transport properties for 2,5...Exploring, designing, and synthesizing novel organic field-effect transistor （OFET） materials have kept an important and hot issue in organic electronics. In the current work, the charge transport properties for 2,5-di（cyanovinyl）thiophene/furan crystal associating two pentafluorophenyl units linked via the azomethine bond, CTE and CFE have been theoretically investigated by means of density functional theory （DFT） calculations coupled with the incoherent charge-hopping mechanism and the kinetic Monte Carlo simulation. Results show that these two compounds possess remarkably low-lying HOMO （-7.0 eV） and LUMO （-4.0 eV） levels, as well as large electron affinities （〉 3.0 eV）, which indicate their high stability exposed to air as promising OFET materials. However, the ph value at room temperature （T = 300 K） is predicted to be 2.058x10^7 cm26Vl·s-1, and the is as low as 9.834^10-8 cm2-V-l.s-1 for CFT crystal. Meanwhile, these two values are 7.561 x 10-8 and 8.437 x 10-8 cm2.V-I.s-1 for the CFE crystal, respectively. Furthermore, the simulation of angle-dependent mobility in the a-b, a-c, and b-c crystal planes shows that the charge transport in CTE and CFE crystals is remarkably anisotropic, which maybe is helpful for the fabrication of high-performance OFET devices.展开更多
Humic acid is a key component of extracellular electron acceptor. Experimental study elucidates that humic acid molecular ligand with different metal elements has different abilities to accept electrons. By using dens...Humic acid is a key component of extracellular electron acceptor. Experimental study elucidates that humic acid molecular ligand with different metal elements has different abilities to accept electrons. By using density functional theory, this article selected the leonardite humic acid(LHA) organic macromolecule as ligand to study interactions between the ligand and different metals. At the same time, the calculation of binding energy, the analysis of characteristics for the complex structure and the distribution of frontier molecular orbital were also completed. On the basis of Marcus theory, the reorganization energy, matrix element and charge transport rate constant were calculated. The results show that the order of the charge transfer rates is Fe^(3+)>Cu^(2+)>Al^(3+) for different metal complexes, and are in good agreement with the experimental ones.展开更多
Using density functional theory and quantum transport calculations based on nonequilibum Green＇s function formalism, we investigate the charge transport properties of endohedral M@C20（M = Na and K） metallofullerene...Using density functional theory and quantum transport calculations based on nonequilibum Green＇s function formalism, we investigate the charge transport properties of endohedral M@C20（M = Na and K） metallofullerenes. Our results show that the conductance of C20 fullerene can be obviously improved by insertion of alkali atom at its centre. Both linear and nonlinear sections are found on the Ⅰ-Ⅴ curves of the Au-M@C20-Au two-probe systems. The novel negative differential resistance behaviour is also observed in Na@C20 molecule but not in K@C20.展开更多
We investigate atomic and electronic structures of boron nanotubes （BNTs） by using the density functional theory （DFT）. The transport properties of BNTs with different diameters and chiralities are studied by the ...We investigate atomic and electronic structures of boron nanotubes （BNTs） by using the density functional theory （DFT）. The transport properties of BNTs with different diameters and chiralities are studied by the Keldysh nonequilibrium Green function （NEGF） method. It is found that the cohesive energies and conductances of BNTs decrease as their diameters decrease. It is more difficult to form （N, 0） tubes than （M, M） tubes when the diameters of the two kinds of tubes are comparable. However, the （N, 0） tubes have a higher conductance than the （M, M） tubes. When the BNTs are connected to gold electrodes, the coupling between the BNTs and the electrodes will affect the transport properties of tubes significantly.展开更多
The Chinese air transport system has witnessed an important evolution in the last decade,with a strong increase in the number of flights operated and a consequent reduction of their punctuality.In this contribution,we...The Chinese air transport system has witnessed an important evolution in the last decade,with a strong increase in the number of flights operated and a consequent reduction of their punctuality.In this contribution,we propose modelling the process of delay propagation by using complex networks,in which nodes are associated to airports,and links between pairs of them are assigned when a delay propagation is detected.Delay time series are analysed through the wellknown Granger Causality,which allows detecting if one time series is causing the dynamics observed in a second one.Results indicate that delays are mostly propagated from small and regional airports,and through flights operated by turbo-prop aircraft,These insights can be used to design strategies for delay propagation dampening,as for instance by including small airports into the system＇s Collaborative Decision Making.展开更多
We present a direct analytical algorithm for solving transportation problems with quadratic function cost coefficients. The algorithm uses the concept of absolute points developed by the authors in earlier works. The ...We present a direct analytical algorithm for solving transportation problems with quadratic function cost coefficients. The algorithm uses the concept of absolute points developed by the authors in earlier works. The versatility of the proposed algorithm is evidenced by the fact that quadratic functions are often used as approximations for other functions, as in, for example, regression analysis. As compared with the earlier international methods for quadratic transportation problem (QTP) which are based on the Lagrangian relaxation approach, the proposed algorithm helps to understand the structure of the QTP better and can guide in managerial decisions. We present a numerical example to illustrate the application of the proposed method.展开更多
The full-potential linear augmented plane wave method based on density functional theory is employed to investigate the electronic structure of BaSi2. With the constant relaxation time and rigid band approximation, th...The full-potential linear augmented plane wave method based on density functional theory is employed to investigate the electronic structure of BaSi2. With the constant relaxation time and rigid band approximation, the electrical conductivity, Seebeck coefficient and figure of merit are calculated by using Boltzmann transport theory, further eval- uated as a function of carrier concentration. We find that the Seebeck coefficient is more anisotropic than electrical conductivity. The figure of merit of BaSi2 is predicted to be quite high at room temperature, implying that optimal doping may be an effective way to improve thermoelectric properties.展开更多
In this work,the electronic transport properties of Z-shaped silicene nanoribbon（ZsSiNR） structure are investigated.The calculations are based on the tight-binding model and Green＇s function method in Landauer-Biit...In this work,the electronic transport properties of Z-shaped silicene nanoribbon（ZsSiNR） structure are investigated.The calculations are based on the tight-binding model and Green＇s function method in Landauer-Biittiker formalism,in which the electronic density of states（DOS）,transmission probability,and current-voltage characteristics of the system are calculated,numerically.It is shown that the geometry of the ZsSiNR structure can play an important role to control the electron transport through the system.It is observed that the intensity of electron localization at the edges of the ZsSiNR decreases with the increase of the spin-orbit interaction（SOI） strength.Also,the semiconductor to metallic transition occurs by increasing the SOI strength.The present theoretical results may be useful to design silicene-based devices in nanoelectronics.展开更多
The structure of a heterojunction made up of an （8, 0） carbon nanotube and an （8, 0） boron nitride nanotube is achieved through geometry optimization implemented in the CASTEP package. Based on the optimized geome...The structure of a heterojunction made up of an （8, 0） carbon nanotube and an （8, 0） boron nitride nanotube is achieved through geometry optimization implemented in the CASTEP package. Based on the optimized geometry, the model of the heterojunction is established. Its transport properties are investigated by combining the nonequilibrium Green＇s function with density functional theory. Results show that both the lowest unoccupied molecular orbital and the highest occupied molecular orbital mainly locate on the carbon nanotube section. In the current-voltage characteristic of the heterojunction, a rectification feature is revealed.展开更多
We investigate the time-modulated electronic and spin transport properties through two T-shaped three-quantum-dot molecules embedded in an Aharonov-Bohm（A-B） interferometer. By using the Keldysh non-equilibrium Gree...We investigate the time-modulated electronic and spin transport properties through two T-shaped three-quantum-dot molecules embedded in an Aharonov-Bohm（A-B） interferometer. By using the Keldysh non-equilibrium Green＇s function technique, the photon-assisted spin-dependent average current is analyzed. The T-shaped three-quantum-dot molecule A-B interferometer exhibits excellent controllability in the average current resonance spectra by adjusting the interdot coupling strength, Rashba spin-orbit coupling strength, magnetic flux, and amplitude of the time-dependent external field.Efficient spin filtering and multiple electron-photon pump functions are exploited in the multi-quantum-dot molecule A-B interferometer by a time-modulated external field.展开更多
In this review, we highlight the recent development of organic π-functional materials as buffer layers in constructing efficient perovskite solar cells（PVSCs）. By following a brief introduction on the PVSC developm...In this review, we highlight the recent development of organic π-functional materials as buffer layers in constructing efficient perovskite solar cells（PVSCs）. By following a brief introduction on the PVSC development, device architecture and material design features, we exemplified the exciting progresses made in field by exploiting organic π-functional materials based hole and electron transport layers（HTLs and ETLs） to enable high-performance PVSCs.展开更多
The transport properties of hexagonal boron-nitride nanoribbons under the uniaxial strain are investigated by the Green＇s function method. We find that the transport properties of armchair boron-nitride nanoribbon st...The transport properties of hexagonal boron-nitride nanoribbons under the uniaxial strain are investigated by the Green＇s function method. We find that the transport properties of armchair boron-nitride nanoribbon strongly depend on the strain. In particular, the features of the conductance steps such as position and width are significantly changed by strain. As a strong tensile strain is exerted on the nanoribbon, the highest conductance step disappears and subsequently a dip emerges instead. The energy band structure and the local current density of armchair boron nitride nanoribbon under strain are calculated and analysed in detail to explain these characteristics. In addition, the effect of strain on the conductance of zigzag boron-nitride nanoribbon is weaker than that of armchair boron nitride nanoribbon.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
基金supported by the National Basic Research Program of China (No. 2006CB101700)the National High- tech Research and Development Program (No. 2006AA10Z165)the Program for New Century Excellent Talents in Uni-versity of China (No. NCET2005-05- 0502).
文摘The high-affinity K＋ （HAK） transporter gene family is the largest family in plant that functions as potassium transporter and is important for various aspects of plant life. In the present study, we identified 27 members of this family in rice genome. The phylogenetic tree divided the land plant HAK transporter proteins into 6 distinct groups. Although the main characteristic of this family was established before the origin of seed plants, they also showed some differences between the members of non-seed and seed plants. The HAK genes in rice were found to have expanded in lineage-specific manner after the split of monocots and dicots, and both segmental duplication events and tandem duplication events contributed to the expansion of this family. Functional divergence analysis for this family provided statistical evidence for shifted evolutionary rate after gene duplication. Further analysis indicated that both point mutant with positive selection and gene conversion events contributed to the evolution of this family in rice.
基金sponsored by King Abdullah University of Science and Technology(KAUST)the National Natural Science Foundation of China(Grant No.91841302)。
文摘We propose a new flame index for the transported probability density function(PDF) method. The flame index uses mixing flux projections of Lagrangian particles on mixture fraction and progress variable directions as the metrics to identify the combustion mode, with the Burke-Schumann solution as a reference. A priori validation of the flame index is conducted with a series of constructed turbulent partially premixed reactors. It indicates that the proposed flame index is able to identify the combustion mode based on the subgrid mixing information. The flame index is then applied the large eddy simulation/PDF datasets of turbulent partially premixed jet flames. Results show that the flame index separate different combustion modes and extinction correctly. The proposed flame index provides a promising tool to analyze and model the partially premixed flames adaptively.
文摘In present paper, the non-equilibrium Green function(NEGF) method along with the density functional theory(DFT) are used to investigate the effect of width on transport and electronic properties of armchair graphyne(γ-graphyne) nanoribbons. The results show that all the studied nanoribbons are semiconductor and their band gaps decrease as the widths of nanoribbons increase, which will result in increasing current at a certain voltage. Also our results show the promising application of armchair graphyne nanoribbons in nano-electrical devices.
基金the support of Shahrekord University under project number 230689
文摘In the present work, firstly, a first-principles study of the structural, electronic, and electron transport properties of the HgxMg1-xTe（HMT） ternary compound is performed using the ABINIT package and the results are compared with Cd0.9Zn0.1 Te（CZT） as a current room-temperature photodetector. Next, the response functions of Hg0.6Mg0.4Te and Cd0.9Zn0.1Te under electromagnetic irradiation with 0.05 Me V, 0.2 MeV, 0.661 MeV and 1.33 MeV energies are simulated by using the MCNP code. According to these simulations, the Hg0.6Mg0.4Te ternary compound is suggested as a good semiconductor photodetector for use at room temperature.
文摘Electroosmotic water vapor transport (WVT) across very thin, flexible, functionalized conducting polymer (CP) microporous (μP) membranes at a very high rate is reported. Both passive and active (6 VDC applied) WVT are reported, the latter for the first time ever. WVT occurs with concomitant, effective blocking of chemical warfare (CW) agents, again demonstrated for the first time ever. Initial active liquid||membrane||liquid interface studies demonstrated WVT rates of >1.7 × 10-5g .mm-2s-1, >3 × the highest prior reported values of 5 × 10-6g.mm-2s-1. Subsequent vapor||membrane|| vapor interface studies using industry-standard methods (including ASTM E96B Upright Cup (“WVT”), ASTM F2298 (“Dynamic Moisture Permeation Cell”) and ASTM F1868 (“Sweating Guard Hotplate”) were done at independent, external labs for independent corroboration. These yielded, e.g., WVT values of2564.4 g.m2.d-1 (passive) and3706.7 g.m2d-1 (active), to be compared with the highest (passive) value ever reported previously,984.8 g.m2.d-1 for a μP-Nylon membrane. More than 15 different membrane configurations, porosities and types were studied, including membranes with CP + organophosphate hydrolase (OPH), an enzyme reactive to CW agents. Efficient blocking of the actual CW agents GB, HD, VX is also reported, using the TOP-8-2-501standard. Membranes also passed all Industry-standard durability tests, e.g. ASTM D2261 (Tearing), ASTM D5034 (Breaking), ASTM D3886 (Abrasion), ASTM F392 (Gelbo Flex). Incorporation into smart soldiers’ garments was demonstrated;power consumption was -2. Mechanisms of enhanced WVT and CW agent blocking in the membranes are discussed.
基金supported the National Natural Science Foundation of China(31572410,31572412,31625025)the 111 Project(B16044)+2 种基金the Program for New Century Excellent Talents in University(NCET-12-0522)the Agriculture and Food Research Initiative Competitive Grant from the USDA National Institute of Food and Agriculture(No.2014-6701521770)Texas A&M Agri Life Research(H-8200)
文摘Background： Cinnamicaldehyde（CA） is a key flavor compound in cinnamon essential oil possessing various bioactivities. Tight junction（TJ） proteins are vital for the maintenance of intestinal epithelial barrier function,transport, absorption and utilization of dietary amino acids and other nutrients. In this study, we tested the hypothesis that CA may regulate the expression of TJ proteins and amino acid transporters in intestinal porcine epithelial cells（IPEC-1） isolated from neonatal pigs.Results： Compared with the control, cells incubated with 25 μmol/L CA had increased transepithelial electrical resistance（TEER） and decreased paracellular intestinal permeability. The beneficial effect of CA on mucosal barrier function was associated with enhanced protein abundance for claudin-4, zonula occludens（ZO）-1, ZO-2, and ZO-3. Immunofluorescence staining showed that 25 μmol/L CA promoted the localization of claudin-1 and claudin-3 to the plasma membrane without affecting the localization of other TJ proteins, including claudin-4, occludin,ZO-1, ZO-2, and ZO-3, compared with the control cells. Moreover, protein abundances for rBAT, xCT and LAT2 in IPEC-1 cells were enhanced by 25 μmol/L CA, while that for EAAT3 was not affected.Conclusions： CA improves intestinal mucosal barrier function by regulating the distribution of claudin-1 and claudin-3 in enterocytes, as well as enhancing protein abundance for amino acid transporters rBAT, xCT and LAT2 in enterocytes. Supplementation with CA may provide an effective nutritional strategy to improve intestinal integrity and amino acid transport and absorption in piglets.
基金supported by the National Natural Science Foundation of China(No.21373132,21173138,21502109)the Doctor Research start foundation of Shaanxi University of Technology(No.SLGKYQD2-13,SLGKYQD2-10,SLGQD14-10)
文摘Exploring, designing, and synthesizing novel organic field-effect transistor （OFET） materials have kept an important and hot issue in organic electronics. In the current work, the charge transport properties for 2,5-di（cyanovinyl）thiophene/furan crystal associating two pentafluorophenyl units linked via the azomethine bond, CTE and CFE have been theoretically investigated by means of density functional theory （DFT） calculations coupled with the incoherent charge-hopping mechanism and the kinetic Monte Carlo simulation. Results show that these two compounds possess remarkably low-lying HOMO （-7.0 eV） and LUMO （-4.0 eV） levels, as well as large electron affinities （〉 3.0 eV）, which indicate their high stability exposed to air as promising OFET materials. However, the ph value at room temperature （T = 300 K） is predicted to be 2.058x10^7 cm26Vl·s-1, and the is as low as 9.834^10-8 cm2-V-l.s-1 for CFT crystal. Meanwhile, these two values are 7.561 x 10-8 and 8.437 x 10-8 cm2.V-I.s-1 for the CFE crystal, respectively. Furthermore, the simulation of angle-dependent mobility in the a-b, a-c, and b-c crystal planes shows that the charge transport in CTE and CFE crystals is remarkably anisotropic, which maybe is helpful for the fabrication of high-performance OFET devices.
基金supported by the Sichuan Province Department Education(13ZA0150)the Sichuan Province(2014JY0099)
文摘Humic acid is a key component of extracellular electron acceptor. Experimental study elucidates that humic acid molecular ligand with different metal elements has different abilities to accept electrons. By using density functional theory, this article selected the leonardite humic acid(LHA) organic macromolecule as ligand to study interactions between the ligand and different metals. At the same time, the calculation of binding energy, the analysis of characteristics for the complex structure and the distribution of frontier molecular orbital were also completed. On the basis of Marcus theory, the reorganization energy, matrix element and charge transport rate constant were calculated. The results show that the order of the charge transfer rates is Fe^(3+)>Cu^(2+)>Al^(3+) for different metal complexes, and are in good agreement with the experimental ones.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10674114 and 10974078)
文摘Using density functional theory and quantum transport calculations based on nonequilibum Green＇s function formalism, we investigate the charge transport properties of endohedral M@C20（M = Na and K） metallofullerenes. Our results show that the conductance of C20 fullerene can be obviously improved by insertion of alkali atom at its centre. Both linear and nonlinear sections are found on the Ⅰ-Ⅴ curves of the Au-M@C20-Au two-probe systems. The novel negative differential resistance behaviour is also observed in Na@C20 molecule but not in K@C20.
基金Project supported by the National Natural Science Foundation of China (Grant No 10774176)the National Basic Research Program of China (Grant Nos 2006CB806202 and 2006CB921305)the Shanghai Supercomputing Center,Chinese Academyof Sciences
文摘We investigate atomic and electronic structures of boron nanotubes （BNTs） by using the density functional theory （DFT）. The transport properties of BNTs with different diameters and chiralities are studied by the Keldysh nonequilibrium Green function （NEGF） method. It is found that the cohesive energies and conductances of BNTs decrease as their diameters decrease. It is more difficult to form （N, 0） tubes than （M, M） tubes when the diameters of the two kinds of tubes are comparable. However, the （N, 0） tubes have a higher conductance than the （M, M） tubes. When the BNTs are connected to gold electrodes, the coupling between the BNTs and the electrodes will affect the transport properties of tubes significantly.
文摘The Chinese air transport system has witnessed an important evolution in the last decade,with a strong increase in the number of flights operated and a consequent reduction of their punctuality.In this contribution,we propose modelling the process of delay propagation by using complex networks,in which nodes are associated to airports,and links between pairs of them are assigned when a delay propagation is detected.Delay time series are analysed through the wellknown Granger Causality,which allows detecting if one time series is causing the dynamics observed in a second one.Results indicate that delays are mostly propagated from small and regional airports,and through flights operated by turbo-prop aircraft,These insights can be used to design strategies for delay propagation dampening,as for instance by including small airports into the system＇s Collaborative Decision Making.
文摘We present a direct analytical algorithm for solving transportation problems with quadratic function cost coefficients. The algorithm uses the concept of absolute points developed by the authors in earlier works. The versatility of the proposed algorithm is evidenced by the fact that quadratic functions are often used as approximations for other functions, as in, for example, regression analysis. As compared with the earlier international methods for quadratic transportation problem (QTP) which are based on the Lagrangian relaxation approach, the proposed algorithm helps to understand the structure of the QTP better and can guide in managerial decisions. We present a numerical example to illustrate the application of the proposed method.
基金supported by the National Basic Research Program of China (Grant No.2007CB607504)Graduate Independent Innovation Foundation of Shandong University (Grant No.yzc09076)
文摘The full-potential linear augmented plane wave method based on density functional theory is employed to investigate the electronic structure of BaSi2. With the constant relaxation time and rigid band approximation, the electrical conductivity, Seebeck coefficient and figure of merit are calculated by using Boltzmann transport theory, further eval- uated as a function of carrier concentration. We find that the Seebeck coefficient is more anisotropic than electrical conductivity. The figure of merit of BaSi2 is predicted to be quite high at room temperature, implying that optimal doping may be an effective way to improve thermoelectric properties.
基金Project supported by the Sari Branch,Islamic Azad University,Iran Grant No.1-24850
文摘In this work,the electronic transport properties of Z-shaped silicene nanoribbon（ZsSiNR） structure are investigated.The calculations are based on the tight-binding model and Green＇s function method in Landauer-Biittiker formalism,in which the electronic density of states（DOS）,transmission probability,and current-voltage characteristics of the system are calculated,numerically.It is shown that the geometry of the ZsSiNR structure can play an important role to control the electron transport through the system.It is observed that the intensity of electron localization at the edges of the ZsSiNR decreases with the increase of the spin-orbit interaction（SOI） strength.Also,the semiconductor to metallic transition occurs by increasing the SOI strength.The present theoretical results may be useful to design silicene-based devices in nanoelectronics.
基金Project supported by the Chinese Defence Advance Research Program of Science and Technology,China (GrantNo. 9140A08060407DZ0103)
文摘The structure of a heterojunction made up of an （8, 0） carbon nanotube and an （8, 0） boron nitride nanotube is achieved through geometry optimization implemented in the CASTEP package. Based on the optimized geometry, the model of the heterojunction is established. Its transport properties are investigated by combining the nonequilibrium Green＇s function with density functional theory. Results show that both the lowest unoccupied molecular orbital and the highest occupied molecular orbital mainly locate on the carbon nanotube section. In the current-voltage characteristic of the heterojunction, a rectification feature is revealed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11447132 and 11504042)the Natural Science Foundation of Heilongjiang,China(Grant No.A201405)+2 种基金111 Project to Harbin Engineering University,China(Grant No.B13015)Chongqing Science and Technology Commission Project,China(Grant Nos.cstc2014jcyj A00032 and cstc2016jcyj A1158)Scientific Research Project for Advanced Talents of Yangtze Normal University,China(Grant No.2017KYQD09)
文摘We investigate the time-modulated electronic and spin transport properties through two T-shaped three-quantum-dot molecules embedded in an Aharonov-Bohm（A-B） interferometer. By using the Keldysh non-equilibrium Green＇s function technique, the photon-assisted spin-dependent average current is analyzed. The T-shaped three-quantum-dot molecule A-B interferometer exhibits excellent controllability in the average current resonance spectra by adjusting the interdot coupling strength, Rashba spin-orbit coupling strength, magnetic flux, and amplitude of the time-dependent external field.Efficient spin filtering and multiple electron-photon pump functions are exploited in the multi-quantum-dot molecule A-B interferometer by a time-modulated external field.
基金financial support from the 973 program(No.2014CB643503)the National Natural Science Foundation of China(No.21474088)+2 种基金financial support from NSFC(No.21674093)the National 1000 Young Talents Program hosted by China100 Talents Program by Zhejiang University
文摘In this review, we highlight the recent development of organic π-functional materials as buffer layers in constructing efficient perovskite solar cells（PVSCs）. By following a brief introduction on the PVSC development, device architecture and material design features, we exemplified the exciting progresses made in field by exploiting organic π-functional materials based hole and electron transport layers（HTLs and ETLs） to enable high-performance PVSCs.
基金Project supported by the Cultivation Fund of the Key Scientific and Technical Innovation Project,Ministry of Education of China(Grant No.708068)the Specialized Research Fund for the Doctoral Program of Higher Education,Ministry of Education of China(Grant No.200805301001)the Open Fund based on Innovation Platform of Hunan Colleges and Universities,China (Grant No.09K034)
文摘The transport properties of hexagonal boron-nitride nanoribbons under the uniaxial strain are investigated by the Green＇s function method. We find that the transport properties of armchair boron-nitride nanoribbon strongly depend on the strain. In particular, the features of the conductance steps such as position and width are significantly changed by strain. As a strong tensile strain is exerted on the nanoribbon, the highest conductance step disappears and subsequently a dip emerges instead. The energy band structure and the local current density of armchair boron nitride nanoribbon under strain are calculated and analysed in detail to explain these characteristics. In addition, the effect of strain on the conductance of zigzag boron-nitride nanoribbon is weaker than that of armchair boron nitride nanoribbon.
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.
