Quantum interference effect serves as a critical strategy for addressing incorrect energy level alignment between frontier molecular orbitals and electrodes in molecular junctions. Weak-coupling structures offer an ef...Quantum interference effect serves as a critical strategy for addressing incorrect energy level alignment between frontier molecular orbitals and electrodes in molecular junctions. Weak-coupling structures offer an effective approach to suppress phonon thermal conductance. The thermoelectric properties of pure C_(3)N_(4) nanoribbon devices and C_(3)N_(4)-C_(20) molecular junctions are systematically investigated based on density functional theory(DFT) combined with nonequilibrium Green's function(NEGF) formalism. The results show that pure C_(3)N_(4) nanoribbon devices have superior charge transport capabilities and excellent Seebeck coefficients. A remarkable thermoelectric figure of merit(ZT = 0.98)is achieved near 0.09 e V. The pronounced scattering effect induced by embedding a C_(20) molecule in the center of the C_(3)N_(4) nanoribbon significantly suppresses phonon transport. A maximum ZT value of 1.68 is observed at 0.987 e V. The electron mobility of C_(3)N_(4)-C_(20)-par is effectively increased due to quantum interference effect which greatly improves the alignment between the C_(20) molecule's frontier orbital energy level and C_(3)N_(4) electrodes. The C_(3)N_(4)-C_(20)-van der Waals(vd W) molecular junction allows very few phonons to pass through the C_(20) molecule from the left electrode to the right electrode. As a result, the C_(3)N_(4)-C_(20)-vd W junction achieves an excellent ZT value of 3.82 near the Femi level.展开更多
A phase-field model integrated with the thermodynamic databases was constructed to investigate the impact of Ni content on the precipitation kinetics and phase transformation of the Cu-rich phase in Fe-Cu-Ni alloy at ...A phase-field model integrated with the thermodynamic databases was constructed to investigate the impact of Ni content on the precipitation kinetics and phase transformation of the Cu-rich phase in Fe-Cu-Ni alloy at 773 K.The results demonstrated that the Cu core-Ni shell structures form via the decomposition of Cu-Ni co-clusters,which is consistent with previous experimental results.As the Ni content increases,both the volume fraction and number density of Cu-rich precipitates increase,while their size decreases.With the increase in Ni content,the transformation from a Cu to 9R Cu is accelerated,which is the opposite to the result of increasing Mn content.Magnetic energy can increase the nucleation rate of the Cu-rich phase,but it does not affect the phase transformation driving force required for its crystal structure transformation.展开更多
The kinetic behavior of leaching copper from low grade copper oxide ore was investigated. The effects of leaching temperature, H2SO4 concentration, particle size of crude ore and agitation rate on the leaching efficie...The kinetic behavior of leaching copper from low grade copper oxide ore was investigated. The effects of leaching temperature, H2SO4 concentration, particle size of crude ore and agitation rate on the leaching efficiency of copper were also evaluated. And the kinetic equations of the leaching process were obtained. The results show that the leaching process can be described with a reaction model of shrinking core. The reaction can be divided into three stages. The first stage is the dissolution of free copper oxide and copper oxide wrapped by hematite-limonite ore. At this stage, the leaching efficiency is very fast （leaching efficiency is larger than 60%）. The second stage is the leaching of diffiuent copper oxides, whose apparent activation energy is 43.26 kJ/mol. During this process, the chemical reaction is the control step, and the reaction order of H2SO4 is 0.433 84. The third stage is the leaching of copper oxide wrapped by hematite-limonite and silicate ore with apparent activation energy of 16.08 kJ/mol, which belongs to the mixed control.展开更多
Cu2ZnSnS4 (CZTS) thin films were successfully prepared by sulfurization of ion bean sputtered precursors on soda-lime glass substrate. The single phase of stannite-type structure CZTS films were obtained as revealed i...Cu2ZnSnS4 (CZTS) thin films were successfully prepared by sulfurization of ion bean sputtered precursors on soda-lime glass substrate. The single phase of stannite-type structure CZTS films were obtained as revealed in EDS and XRD analysis when the ratios of the constituents of CZTS thin films are close to stoichiometric by optimizing the conditions of precursor preparation and sulfurization. A low sheet resistivity as about 0.156 Ω·cm and a high absorption coefficient as 1×104 cm-1 were achieved in this method by Hall effect measurements and UV-VIS spectrophotometer. The optical band-gap energy of the CZTS sample is about 1.51 eV, which is very close to the optimum value for a solar-cell absorber.展开更多
A novel approach to image hemoglobin concentration（△Dhb） and oxygen saturation （△Doxy） of breast tissue is presented. The scenograph of dual-wavelength （760 and 850 nm） near infrared lights through breast tiss...A novel approach to image hemoglobin concentration（△Dhb） and oxygen saturation （△Doxy） of breast tissue is presented. The scenograph of dual-wavelength （760 and 850 nm） near infrared lights through breast tissue is acquired by high sensitive charge coupled device （CCD） camera. The evaluation criterion of the difference of △Dhh and △Doxy between detected and referenced breast tissue can be obtained by a calculation formula without complicate caculation. This approach is applied to clinic detection in breast tissue. The ongoing clinical experiments indicate that malignant tumor usually exhibits characterize of ＂higher △Dhb and lower △Doxy＂, while benign lesion often shows ＂lower △Dhb and higher △Doxy＂ or other characters. So it is useful to assist the diagnosis of breast disease.展开更多
An approximate Fokker-Planck equation for the logistic growth model which is driven by coloured correlated noises is derived by applying the Novikov theorem and the Fox approximation. The steady-state probability dist...An approximate Fokker-Planck equation for the logistic growth model which is driven by coloured correlated noises is derived by applying the Novikov theorem and the Fox approximation. The steady-state probability distribution （SPD） and the mean of the tumour cell number are analysed. It is found that the SPD is the single extremum configuration when the degree of correlation between the multiplicative and additive noises, λ is in -1 〈λ≤0 and can be the double extrema in 0〈λ〈1. A configuration transition occurs because of the variation of noise parameters. A minimum appears in the curve of the mean of the steady-state tumour cell number, （x）, versus λ The position and the value of the minimum are controlled by the noise-correlated times.展开更多
The Al-Mg-Mn alloy sheets with and without trace Sc and Zr were investigated by means of tensile test,X-ray diffraction,optical microscope,and transmission electron microscope.The indexes of in-plane anisotropy(IIPA)o...The Al-Mg-Mn alloy sheets with and without trace Sc and Zr were investigated by means of tensile test,X-ray diffraction,optical microscope,and transmission electron microscope.The indexes of in-plane anisotropy(IIPA)of their tensile mechanical properties were calculated and their inverse pole figures were obtained by Harris method.The two alloy sheets have the same law of in-plane anisotropy and remarkable in-plane anisotropy of mechanical properties,and the IIPA of the alloy sheet with Sc and Zr is bigger than that of the alloy sheet without Sc and Zr.The relationships of the in-plane anisotropy and the anisotropy of the crystallographic texture were analyzed based on the model of monocrystal.It is the common action of the anisotropy of crystallography and microstructures that causes the in-plane anisotropy of their mechanical properties,but the major cause is the{110}〈112〉crystallographic texture.The trace Sc and Zr can promote the formation and stabilization of the{110}〈112〉texture,inhibit the formation of the{100}〈001〉texture,and increase the in-plane anisotropy of the alloy sheet containing trace Sc and Zr.展开更多
The influence of polyvinylpyrrolidone(PVP)and monoethanolamine(MEA)as surfactants on photoluminescence(PL)of Eu-doped ZnO(ZnO:Eu)has been studied.X-ray diffraction(XRD)results show that there are more Eu3+ions to repl...The influence of polyvinylpyrrolidone(PVP)and monoethanolamine(MEA)as surfactants on photoluminescence(PL)of Eu-doped ZnO(ZnO:Eu)has been studied.X-ray diffraction(XRD)results show that there are more Eu3+ions to replace Zn^2+ ions into ZnO lattice for ZnO:Eu in the presence of surfactant MEA.From the spectral analysis for ZnO:Eu with different surfactants by Gaussian deconvolution,it can be seen that the use of MEA as a surfactant affects the energy transfer from ZnO host to Eu^3+ions and leads to three new emission peaks,including UV emission(389 nm),violet emission(411 nm)and green emission(506 nm).展开更多
This paper proposes a simple scheme to generate a four-atom entangled cluster state in cavity quantum electrodynamics. With the assistantce of a strong classical field the cavity is only virtually excited and no quant...This paper proposes a simple scheme to generate a four-atom entangled cluster state in cavity quantum electrodynamics. With the assistantce of a strong classical field the cavity is only virtually excited and no quantum information will be transferred from the atoms to the cavity during the preparation for a four-atom entangled cluster state, and thus the scheme is insensitive to the cavity field states and cavity decay. Assuming that deviation of laser intensity is 0.01 and that of simultaneity for the interaction is 0.01, it shows that the fidelity of the resulting four-atom entangled cluster state is about 0.9886. The scheme can also be used to generate a four-ion entangled cluster state in a hot trapped-ion system. Assuming that deviation of laser intensity is 0.01, it shows that the fidelity of the resulting four-ion entangled cluster state is about 0.9990. Experimental feasibility for achieving this scheme is also discussed.展开更多
In order to simulate the stress of turbine rotor in aeroengine, based on the ANSYS, the simplification model of the turbine rotor was built up. By applying the simplification model, the contact stress of turbine rotor...In order to simulate the stress of turbine rotor in aeroengine, based on the ANSYS, the simplification model of the turbine rotor was built up. By applying the simplification model, the contact stress of turbine rotor was computed. The maximum contact stress appears at the chamfer below the flank, which agrees with experiment result. At the same time, the contact stress changing with the flank angle and friction coefficient was calculated, The results show that the contact stress in the flank increases slowly with the increase of flank angle; with the friction coefficient increasing, the contact stress in flank length decreases; the contact stress will not change when the friction coefficient is over 0.25.展开更多
Ta2O5 thin films were deposited by DC reactive magnetron sputtering followed by rapid thermal annealing(RTA). Influence of sputtering pressure and annealing temperature on surface characteristics,microstructure and op...Ta2O5 thin films were deposited by DC reactive magnetron sputtering followed by rapid thermal annealing(RTA). Influence of sputtering pressure and annealing temperature on surface characteristics,microstructure and optical property of Ta2O5 thin films were investigated. As-deposited Ta2O5 thin films are amorphous. It takes hexagonal structure(δ-Ta2O5) after being annealed at 800 ℃. A transition from δ-Ta2O5 to orthorhombic structure(L-Ta2O5) occurs at 900-1 000 ℃. Surface roughness is decreased after annealing at low temperature. Refractive index and extinction coefficient are decreased when annealing temperature is increased.展开更多
The binding energy and Stark effect energy shifts of a shallow donor impurity state in a strained GaN/AlxGa1-xN spherical finite-potential quantum dot (QD) are calculated using a variational method based on the effect...The binding energy and Stark effect energy shifts of a shallow donor impurity state in a strained GaN/AlxGa1-xN spherical finite-potential quantum dot (QD) are calculated using a variational method based on the effective mass approximation. The binding energy is computed as a function of dot size and hydrostatic pressure. The numerical results show that the binding energy of the impurity state increases, attains a maximum value, and then decreases as the QD radius increases for any electric field. Moreover, the binding energy increases with the pressure for any size of dot. The Stark shift of the impurity energy for large dot size is much larger than that for the small dot size, and it is enhanced by the increase of electric field. We compare the binding energy of impurity state with and without strain effects, and the results show that the strain effects enhance the impurity binding energy considerably, especially for the small QD size. We also take the dielectric mismatch into account in our work.展开更多
We investigate the effect of CH-doped and F-doped on dielectric properties of SiCOH films deposited by de- camethylcyclopentasiloxane （DMCPS） electron cyclotron resonance plasma. The dielectric constant k is closely...We investigate the effect of CH-doped and F-doped on dielectric properties of SiCOH films deposited by de- camethylcyclopentasiloxane （DMCPS） electron cyclotron resonance plasma. The dielectric constant k is closely related to the configurations of films. For the films deposited only using DMCPS, the minimum k is as low as 2.88. By adding CH4 in the precursor, the k value can be reduced to 2.45 due to the film density decreasing by incorporating large size CHx groups. By adding CHF3 in the precursor, the k value can also be reduced to 2.48 due to the incorporation of the weak-polarization F atom. Thus the dielectric constant for SiCOH films depends on not only the film density but also the polarization of atoms. By increasing the film density or by reducing the polarization of atoms under the condition of a lower film density, the low dielectric constant SiCOH films can be obtained.展开更多
SiC thin-films were prepared by RF-magnetron sputtering technique(RMS) with the target of single crystalline SiC and then annealed. The surface morphology of thin-films was characterized by AFM. The result shows that ...SiC thin-films were prepared by RF-magnetron sputtering technique(RMS) with the target of single crystalline SiC and then annealed. The surface morphology of thin-films was characterized by AFM. The result shows that the surface of the thin-films is smooth and compact; XRD analysis reveals that the thin-films are amorphous. The thickness, square-resistance and curves of resistance—temperature were measured. The results show that the curves of lnR versus 1/kT both before and after annealing satisfy the expression of lnR∝△W/kT, where ?W is electron excitation energy in the range of 0.014 2-0.018 5 eV, and it has a trend of increasing when the temperature is increased. After synthetical analysis we get the conclusion that the electronic mechanism of the thin-films is short distance transition between the localized states in the temperature range of 25-250 ℃. The resistivity is in the range of 2.4×10-3-4.4×10-3 Ω·cm and it has the same trend as electron excitation energy when annealing temperature is increased, which further confirms the electronic mechanism of thin-films and the trend of electron excitation energy versus annealing temperature.展开更多
We present complete next-to-leading-order(NLO)QCD correction and electro-weak(EW)correction to the production cross section of Higgs–Boson in association with two hard quark jets by using Monte-Carlo numerical calcul...We present complete next-to-leading-order(NLO)QCD correction and electro-weak(EW)correction to the production cross section of Higgs–Boson in association with two hard quark jets by using Monte-Carlo numerical calculation program,HAWK,for various photon parton distribution functions at the Large Hadron Collider with center of mass energy 7,8,13,and 14 TeV without and with typical vector-Boson-fusion cuts on the tagging jets.In our calculation we include complete contribution from the full set of t-channel,u-channel and s-channel Feynman diagrams,and corresponding interferences as well as NLO QCD and EW corrections.展开更多
To design a hyperchaotic generator and apply chaos into secure communication, a linear unidirectional coupling control is applied to two identical simplified Lorenz systems. The dynamical evolution process of the coup...To design a hyperchaotic generator and apply chaos into secure communication, a linear unidirectional coupling control is applied to two identical simplified Lorenz systems. The dynamical evolution process of the coupled system is investigated with variations of the system parameter and coupling coefficients. Particularly, the influence of coupling strength on dynamics of the coupled system is analyzed in detail. The range of the coupling strength in which the coupled system can generate hyperchaos or realize synchronization is determined, including phase portraits, Lyapunov exponents, and Poincare section. And the critical value of the system parameter between hyperchaos and synchronization is also found with fixed coupled strength. In addition, abundant dynamical behaviors such as four-wing hyperchaotic, two-wing chaotic, single-wing coexisting attractors and periodic orbits are observed and chaos synchronization error curves are also drawn by varying system parameter c. Numerical simulations are implemented to verify the results of these investigations.展开更多
We investigate the temporal evolution of the current pulses from an ac Fie cold plasma jet at atmospheric pressure and with driving frequency in the range 14.76-15.30 kHz. The driving frequency is used as the plasma s...We investigate the temporal evolution of the current pulses from an ac Fie cold plasma jet at atmospheric pressure and with driving frequency in the range 14.76-15.30 kHz. The driving frequency is used as the plasma system＇s bifurcation parameter in analogy with the evolution in which the current pulses undergoes multiplication and chaos. Such time-domain nonlineaxity is important for controlling instabilities in atmospheric glow discharges. In addition, the observation can provide some data to support the simulation results reported previously [Appl. Phys. Lett. 90 （2007） 071501].展开更多
The spin-reorientation transition of intermetallic compound DyMn6Sn6 was investigated by applying the molecular field theory. The temperature dependence of easy magnetization direction of compound and the magnetic mom...The spin-reorientation transition of intermetallic compound DyMn6Sn6 was investigated by applying the molecular field theory. The temperature dependence of easy magnetization direction of compound and the magnetic moment directions of Dy and Mn ions were theoretically calculated and they have good agreement with the experimental data. In the framework of single ion model, the temperature dependence of magnetocrystalline anisotropic constants K1R and K2R of Dy ion were also calculated. The results show that the fourth-order crystal field parameter, B 40, and the corresponding second-order magnetocrystalline anisotropic constant, K2R, of Dy ion must be taken into account in order to explain the spin-reorientation transition satisfactorily. The competition between K2R and K1R plays a key role in the spin-reorientation transition of DyMn6Sn6.展开更多
The Si3N4-based nanocomposites reinforced with micro ZrO2 and nano SiC particles were prepared by polarity dispersant and vacuum-sintering technology. The mechanical properties and microstructures were tested. The res...The Si3N4-based nanocomposites reinforced with micro ZrO2 and nano SiC particles were prepared by polarity dispersant and vacuum-sintering technology. The mechanical properties and microstructures were tested. The results show that appropriate amount of micro ZrO2 and nano SiC particles, not only enhance the microhardness, but also block the excessively growth of β-Si3N4 and β-Si3N4 grains, so they finally all grow up to uniformly pole-shaped grains. This process is similar to the strengthening and toughening mechanism of grain whiskers and makes a remarkable improvement on the toughness. Compared with Si3N4 ceramic, the toughness of Si3N4/SiC/ZrO2 nanocomposites are increased from 6.2 MPa·m1/2 to 11 MPa·m1/2.展开更多
In this work, BaWO4 nanospheres were successfully prepared by hydrothermal process. The bipolar resistive switching behavior of Ag/BaWO4/FTO device is observed. Moreover, this resistive switching behavior can be modul...In this work, BaWO4 nanospheres were successfully prepared by hydrothermal process. The bipolar resistive switching behavior of Ag/BaWO4/FTO device is observed. Moreover, this resistive switching behavior can be modulated by white light. The device can maintain superior stability in the dark and under white-light illumination. This study is useful for developing the light-controlled nonvolatile memory devices.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 12164046)。
文摘Quantum interference effect serves as a critical strategy for addressing incorrect energy level alignment between frontier molecular orbitals and electrodes in molecular junctions. Weak-coupling structures offer an effective approach to suppress phonon thermal conductance. The thermoelectric properties of pure C_(3)N_(4) nanoribbon devices and C_(3)N_(4)-C_(20) molecular junctions are systematically investigated based on density functional theory(DFT) combined with nonequilibrium Green's function(NEGF) formalism. The results show that pure C_(3)N_(4) nanoribbon devices have superior charge transport capabilities and excellent Seebeck coefficients. A remarkable thermoelectric figure of merit(ZT = 0.98)is achieved near 0.09 e V. The pronounced scattering effect induced by embedding a C_(20) molecule in the center of the C_(3)N_(4) nanoribbon significantly suppresses phonon transport. A maximum ZT value of 1.68 is observed at 0.987 e V. The electron mobility of C_(3)N_(4)-C_(20)-par is effectively increased due to quantum interference effect which greatly improves the alignment between the C_(20) molecule's frontier orbital energy level and C_(3)N_(4) electrodes. The C_(3)N_(4)-C_(20)-van der Waals(vd W) molecular junction allows very few phonons to pass through the C_(20) molecule from the left electrode to the right electrode. As a result, the C_(3)N_(4)-C_(20)-vd W junction achieves an excellent ZT value of 3.82 near the Femi level.
基金supported by the National Natural Science Foundation of China(Grant No.51871086).
文摘A phase-field model integrated with the thermodynamic databases was constructed to investigate the impact of Ni content on the precipitation kinetics and phase transformation of the Cu-rich phase in Fe-Cu-Ni alloy at 773 K.The results demonstrated that the Cu core-Ni shell structures form via the decomposition of Cu-Ni co-clusters,which is consistent with previous experimental results.As the Ni content increases,both the volume fraction and number density of Cu-rich precipitates increase,while their size decreases.With the increase in Ni content,the transformation from a Cu to 9R Cu is accelerated,which is the opposite to the result of increasing Mn content.Magnetic energy can increase the nucleation rate of the Cu-rich phase,but it does not affect the phase transformation driving force required for its crystal structure transformation.
基金Project(2005BA639C) supported by the National Science and Technology Development of China
文摘The kinetic behavior of leaching copper from low grade copper oxide ore was investigated. The effects of leaching temperature, H2SO4 concentration, particle size of crude ore and agitation rate on the leaching efficiency of copper were also evaluated. And the kinetic equations of the leaching process were obtained. The results show that the leaching process can be described with a reaction model of shrinking core. The reaction can be divided into three stages. The first stage is the dissolution of free copper oxide and copper oxide wrapped by hematite-limonite ore. At this stage, the leaching efficiency is very fast （leaching efficiency is larger than 60%）. The second stage is the leaching of diffiuent copper oxides, whose apparent activation energy is 43.26 kJ/mol. During this process, the chemical reaction is the control step, and the reaction order of H2SO4 is 0.433 84. The third stage is the leaching of copper oxide wrapped by hematite-limonite and silicate ore with apparent activation energy of 16.08 kJ/mol, which belongs to the mixed control.
基金This work was financially supported by the National Natural Science Foundation (No.10574106), the Science & Technology Plan of Guangdong Province (No.2003C105005) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars of Chinese State Education Ministry (No.(2004)176).
文摘Cu2ZnSnS4 (CZTS) thin films were successfully prepared by sulfurization of ion bean sputtered precursors on soda-lime glass substrate. The single phase of stannite-type structure CZTS films were obtained as revealed in EDS and XRD analysis when the ratios of the constituents of CZTS thin films are close to stoichiometric by optimizing the conditions of precursor preparation and sulfurization. A low sheet resistivity as about 0.156 Ω·cm and a high absorption coefficient as 1×104 cm-1 were achieved in this method by Hall effect measurements and UV-VIS spectrophotometer. The optical band-gap energy of the CZTS sample is about 1.51 eV, which is very close to the optimum value for a solar-cell absorber.
文摘A novel approach to image hemoglobin concentration（△Dhb） and oxygen saturation （△Doxy） of breast tissue is presented. The scenograph of dual-wavelength （760 and 850 nm） near infrared lights through breast tissue is acquired by high sensitive charge coupled device （CCD） camera. The evaluation criterion of the difference of △Dhh and △Doxy between detected and referenced breast tissue can be obtained by a calculation formula without complicate caculation. This approach is applied to clinic detection in breast tissue. The ongoing clinical experiments indicate that malignant tumor usually exhibits characterize of ＂higher △Dhb and lower △Doxy＂, while benign lesion often shows ＂lower △Dhb and higher △Doxy＂ or other characters. So it is useful to assist the diagnosis of breast disease.
基金Supported by the National Natural Science Foundation of China under Grant No 10275025, and the Key Project of Education Bureau of Hubei Province under Grant No Z200612001.
文摘An approximate Fokker-Planck equation for the logistic growth model which is driven by coloured correlated noises is derived by applying the Novikov theorem and the Fox approximation. The steady-state probability distribution （SPD） and the mean of the tumour cell number are analysed. It is found that the SPD is the single extremum configuration when the degree of correlation between the multiplicative and additive noises, λ is in -1 〈λ≤0 and can be the double extrema in 0〈λ〈1. A configuration transition occurs because of the variation of noise parameters. A minimum appears in the curve of the mean of the steady-state tumour cell number, （x）, versus λ The position and the value of the minimum are controlled by the noise-correlated times.
基金This work was financially supported by the National Key Fundamental Research Development Program(No.G1999064911).
文摘The Al-Mg-Mn alloy sheets with and without trace Sc and Zr were investigated by means of tensile test,X-ray diffraction,optical microscope,and transmission electron microscope.The indexes of in-plane anisotropy(IIPA)of their tensile mechanical properties were calculated and their inverse pole figures were obtained by Harris method.The two alloy sheets have the same law of in-plane anisotropy and remarkable in-plane anisotropy of mechanical properties,and the IIPA of the alloy sheet with Sc and Zr is bigger than that of the alloy sheet without Sc and Zr.The relationships of the in-plane anisotropy and the anisotropy of the crystallographic texture were analyzed based on the model of monocrystal.It is the common action of the anisotropy of crystallography and microstructures that causes the in-plane anisotropy of their mechanical properties,but the major cause is the{110}〈112〉crystallographic texture.The trace Sc and Zr can promote the formation and stabilization of the{110}〈112〉texture,inhibit the formation of the{100}〈001〉texture,and increase the in-plane anisotropy of the alloy sheet containing trace Sc and Zr.
基金supported by the National Natural Science Foundation of China(No.61665011)the Xinjiang Science and Technology Project(No.2019D01C036)the Xinjiang University Doctoral Research Initiation Project(No.62008010)。
文摘The influence of polyvinylpyrrolidone(PVP)and monoethanolamine(MEA)as surfactants on photoluminescence(PL)of Eu-doped ZnO(ZnO:Eu)has been studied.X-ray diffraction(XRD)results show that there are more Eu3+ions to replace Zn^2+ ions into ZnO lattice for ZnO:Eu in the presence of surfactant MEA.From the spectral analysis for ZnO:Eu with different surfactants by Gaussian deconvolution,it can be seen that the use of MEA as a surfactant affects the energy transfer from ZnO host to Eu^3+ions and leads to three new emission peaks,including UV emission(389 nm),violet emission(411 nm)and green emission(506 nm).
基金Project supported by the Postdoctal Foundation of Central South University of Chinathe Important Program of Hunan Provincial Education Department of China (Grant No. 06A038)+1 种基金Department of Education of Hunan Province of China (Grant No. 06C080)Hunan Provincial Natural Science Foundation,China (Grant No. 07JJ3013)
文摘This paper proposes a simple scheme to generate a four-atom entangled cluster state in cavity quantum electrodynamics. With the assistantce of a strong classical field the cavity is only virtually excited and no quantum information will be transferred from the atoms to the cavity during the preparation for a four-atom entangled cluster state, and thus the scheme is insensitive to the cavity field states and cavity decay. Assuming that deviation of laser intensity is 0.01 and that of simultaneity for the interaction is 0.01, it shows that the fidelity of the resulting four-atom entangled cluster state is about 0.9886. The scheme can also be used to generate a four-ion entangled cluster state in a hot trapped-ion system. Assuming that deviation of laser intensity is 0.01, it shows that the fidelity of the resulting four-ion entangled cluster state is about 0.9990. Experimental feasibility for achieving this scheme is also discussed.
基金Foundation item： Project（1774-107101027） supported by the National Defense Fund of China Project（1343-74236000006） supported by the Graduate Foundation of Flunan Province, China
文摘In order to simulate the stress of turbine rotor in aeroengine, based on the ANSYS, the simplification model of the turbine rotor was built up. By applying the simplification model, the contact stress of turbine rotor was computed. The maximum contact stress appears at the chamfer below the flank, which agrees with experiment result. At the same time, the contact stress changing with the flank angle and friction coefficient was calculated, The results show that the contact stress in the flank increases slowly with the increase of flank angle; with the friction coefficient increasing, the contact stress in flank length decreases; the contact stress will not change when the friction coefficient is over 0.25.
基金Project(60371046) supported by the National Natural Science Foundation of China
文摘Ta2O5 thin films were deposited by DC reactive magnetron sputtering followed by rapid thermal annealing(RTA). Influence of sputtering pressure and annealing temperature on surface characteristics,microstructure and optical property of Ta2O5 thin films were investigated. As-deposited Ta2O5 thin films are amorphous. It takes hexagonal structure(δ-Ta2O5) after being annealed at 800 ℃. A transition from δ-Ta2O5 to orthorhombic structure(L-Ta2O5) occurs at 900-1 000 ℃. Surface roughness is decreased after annealing at low temperature. Refractive index and extinction coefficient are decreased when annealing temperature is increased.
基金supported by the National Natural Science Foundation of China (No.10964006)the Research Funds for the Science and Technology Innovation Team of Inner Mongolia Agricultural University (No. NDPYTD2010-7)
文摘The binding energy and Stark effect energy shifts of a shallow donor impurity state in a strained GaN/AlxGa1-xN spherical finite-potential quantum dot (QD) are calculated using a variational method based on the effective mass approximation. The binding energy is computed as a function of dot size and hydrostatic pressure. The numerical results show that the binding energy of the impurity state increases, attains a maximum value, and then decreases as the QD radius increases for any electric field. Moreover, the binding energy increases with the pressure for any size of dot. The Stark shift of the impurity energy for large dot size is much larger than that for the small dot size, and it is enhanced by the increase of electric field. We compare the binding energy of impurity state with and without strain effects, and the results show that the strain effects enhance the impurity binding energy considerably, especially for the small QD size. We also take the dielectric mismatch into account in our work.
文摘We investigate the effect of CH-doped and F-doped on dielectric properties of SiCOH films deposited by de- camethylcyclopentasiloxane （DMCPS） electron cyclotron resonance plasma. The dielectric constant k is closely related to the configurations of films. For the films deposited only using DMCPS, the minimum k is as low as 2.88. By adding CH4 in the precursor, the k value can be reduced to 2.45 due to the film density decreasing by incorporating large size CHx groups. By adding CHF3 in the precursor, the k value can also be reduced to 2.48 due to the incorporation of the weak-polarization F atom. Thus the dielectric constant for SiCOH films depends on not only the film density but also the polarization of atoms. By increasing the film density or by reducing the polarization of atoms under the condition of a lower film density, the low dielectric constant SiCOH films can be obtained.
基金Project(60371046) supported by the National Natural Science Foundation of China
文摘SiC thin-films were prepared by RF-magnetron sputtering technique(RMS) with the target of single crystalline SiC and then annealed. The surface morphology of thin-films was characterized by AFM. The result shows that the surface of the thin-films is smooth and compact; XRD analysis reveals that the thin-films are amorphous. The thickness, square-resistance and curves of resistance—temperature were measured. The results show that the curves of lnR versus 1/kT both before and after annealing satisfy the expression of lnR∝△W/kT, where ?W is electron excitation energy in the range of 0.014 2-0.018 5 eV, and it has a trend of increasing when the temperature is increased. After synthetical analysis we get the conclusion that the electronic mechanism of the thin-films is short distance transition between the localized states in the temperature range of 25-250 ℃. The resistivity is in the range of 2.4×10-3-4.4×10-3 Ω·cm and it has the same trend as electron excitation energy when annealing temperature is increased, which further confirms the electronic mechanism of thin-films and the trend of electron excitation energy versus annealing temperature.
基金supported by the National Natural Science Foundation of China under the Grant No.11965020。
文摘We present complete next-to-leading-order(NLO)QCD correction and electro-weak(EW)correction to the production cross section of Higgs–Boson in association with two hard quark jets by using Monte-Carlo numerical calculation program,HAWK,for various photon parton distribution functions at the Large Hadron Collider with center of mass energy 7,8,13,and 14 TeV without and with typical vector-Boson-fusion cuts on the tagging jets.In our calculation we include complete contribution from the full set of t-channel,u-channel and s-channel Feynman diagrams,and corresponding interferences as well as NLO QCD and EW corrections.
基金Projects(61073187,61161006) supported by the National Nature Science Foundation of ChinaProject supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,China
文摘To design a hyperchaotic generator and apply chaos into secure communication, a linear unidirectional coupling control is applied to two identical simplified Lorenz systems. The dynamical evolution process of the coupled system is investigated with variations of the system parameter and coupling coefficients. Particularly, the influence of coupling strength on dynamics of the coupled system is analyzed in detail. The range of the coupling strength in which the coupled system can generate hyperchaos or realize synchronization is determined, including phase portraits, Lyapunov exponents, and Poincare section. And the critical value of the system parameter between hyperchaos and synchronization is also found with fixed coupled strength. In addition, abundant dynamical behaviors such as four-wing hyperchaotic, two-wing chaotic, single-wing coexisting attractors and periodic orbits are observed and chaos synchronization error curves are also drawn by varying system parameter c. Numerical simulations are implemented to verify the results of these investigations.
文摘We investigate the temporal evolution of the current pulses from an ac Fie cold plasma jet at atmospheric pressure and with driving frequency in the range 14.76-15.30 kHz. The driving frequency is used as the plasma system＇s bifurcation parameter in analogy with the evolution in which the current pulses undergoes multiplication and chaos. Such time-domain nonlineaxity is important for controlling instabilities in atmospheric glow discharges. In addition, the observation can provide some data to support the simulation results reported previously [Appl. Phys. Lett. 90 （2007） 071501].
基金Project(60571043) supported by the National Natural Science Foundation of ChinaProject(03JJY4044) supported by the Natural Science Foundation of Hunan Province, China
文摘The spin-reorientation transition of intermetallic compound DyMn6Sn6 was investigated by applying the molecular field theory. The temperature dependence of easy magnetization direction of compound and the magnetic moment directions of Dy and Mn ions were theoretically calculated and they have good agreement with the experimental data. In the framework of single ion model, the temperature dependence of magnetocrystalline anisotropic constants K1R and K2R of Dy ion were also calculated. The results show that the fourth-order crystal field parameter, B 40, and the corresponding second-order magnetocrystalline anisotropic constant, K2R, of Dy ion must be taken into account in order to explain the spin-reorientation transition satisfactorily. The competition between K2R and K1R plays a key role in the spin-reorientation transition of DyMn6Sn6.
文摘The Si3N4-based nanocomposites reinforced with micro ZrO2 and nano SiC particles were prepared by polarity dispersant and vacuum-sintering technology. The mechanical properties and microstructures were tested. The results show that appropriate amount of micro ZrO2 and nano SiC particles, not only enhance the microhardness, but also block the excessively growth of β-Si3N4 and β-Si3N4 grains, so they finally all grow up to uniformly pole-shaped grains. This process is similar to the strengthening and toughening mechanism of grain whiskers and makes a remarkable improvement on the toughness. Compared with Si3N4 ceramic, the toughness of Si3N4/SiC/ZrO2 nanocomposites are increased from 6.2 MPa·m1/2 to 11 MPa·m1/2.
基金supported by the National Nature Science Foundation of China (Grant No. 51372209)
文摘In this work, BaWO4 nanospheres were successfully prepared by hydrothermal process. The bipolar resistive switching behavior of Ag/BaWO4/FTO device is observed. Moreover, this resistive switching behavior can be modulated by white light. The device can maintain superior stability in the dark and under white-light illumination. This study is useful for developing the light-controlled nonvolatile memory devices.
