Due to the lack of surface dangling bonds in graphene,the direct growth of high-κ films via atomic layer deposition(ALD) technique often produces the dielectrics with a poor quality,which hinders its integration in m...Due to the lack of surface dangling bonds in graphene,the direct growth of high-κ films via atomic layer deposition(ALD) technique often produces the dielectrics with a poor quality,which hinders its integration in modern semiconductor industry.Previous pretreatment approaches,such as chemical functionalization with ozone and plasma treatments,would inevitably degrade the quality of the underlying graphene.Here,we tackled this problem by utilizing an effective and convenient physical method.In detail,the graphene surface was pretreated with the deposition of thermally evaporated ultrathin Al metal layer prior to the Al2O3 growth by ALD.Then the device was placed in a drying oven for 30 min to be naturally oxidized as a seed layer.With the assistance of an Al oxide seed layer,pinhole-free Al2O3 dielectrics growth on graphene was achieved.No detective defects or disorders were introduced into graphene by Raman characterization.Moreover,our fabricated graphene topgated field effect transistor exhibited high mobility(~6200 cm2V-1s-1) and high transconductance(~117 μS).Thin dielectrics demonstrated a relative permittivity of 6.5 over a large area and a leakage current less than1.6 p A/μm2.These results indicate that Al oxide functionalization is a promising pathway to achieve scaled gate dielectrics on graphene with high performance.展开更多
Accurate non-Born-Oppenheimer variational calculations of all bound states of the positive muon molecular ion 4Heμ^+ have been performed using explicitly correlated Gaussian functions in conjunction with the global v...Accurate non-Born-Oppenheimer variational calculations of all bound states of the positive muon molecular ion 4Heμ^+ have been performed using explicitly correlated Gaussian functions in conjunction with the global vectors.All the energies obtained are accurate in the order of 10-6 Hartree(1 Hartree=27.2114 eV).Compared with the binding energies obtained from calculations based on the Born-Oppenheimer potential with the mass-weighted adiabatic corrections(Chem.Phys.Lett.110487(1984)),the largest relative deviation is up to 15%.By analyzing the average interparticle distances and possibility distributions of interparticle distances of this system,it is confirmed that the Born-Oppenheimer approximation is reasonable for this system and that 4Heμ^+ can be regarded as a system of positive muon bound to a slightly distorted helium atom.展开更多
We analyze the transverse momentum dependence of HBT radii in relativistic heavy-ion collisions using several source models.Results indicate that the single-particle space-momentum angle distribution plays an importan...We analyze the transverse momentum dependence of HBT radii in relativistic heavy-ion collisions using several source models.Results indicate that the single-particle space-momentum angle distribution plays an important role in the transverse momentum dependence of HBT radii.In a cylinder source,we use several formulas to describe the transverse momentum dependence of HBT radii and the single-particle space-momentum angle distribution.We also make a numerical connection between them in the transverse plane.展开更多
It is well known that the full compressible Navier-Stokes equations with viscosity and heat conductivity coefficients of order of the Knudsen number ò>0 can be deduced from the Boltzmann equation via the Chapm...It is well known that the full compressible Navier-Stokes equations with viscosity and heat conductivity coefficients of order of the Knudsen number ò>0 can be deduced from the Boltzmann equation via the Chapman-Enskog expansion. In this paper, we carry out the rigorous mathematical study of the compressible Navier-Stokes equation with the initial-boundary value problems. We construct the existence and most importantly obtain the higher regularities of the solutions of the full compressible Navier-Stokes system with weak viscosity and heat conductivity in a general bounded domain.展开更多
We investigate the influence of coating layer on acoustic wave propagation in a dispersed random medium consisting of coa.ted fibers.In the strong-scattering regime, the characteristics of wave scattering resonances a...We investigate the influence of coating layer on acoustic wave propagation in a dispersed random medium consisting of coa.ted fibers.In the strong-scattering regime, the characteristics of wave scattering resonances are found to evolve regularly with the properties of the coating layer.By theoretical calculation,frequency gaps are found in acoustic excitation spectra in a random medium.The scattering cross section results present the evolution of scattering resonances with the properties of the coating layer,which offers a good explanation for the change of the frequency gaps.The velocity of the propagation quasi-mode is also shown to depend on the filling fraction of the coating layer.We use the generalized coherent potential-approximation approach to solve acoustic wave dispersion relations in a complicated random medium consisting of coating-structure scatterers.It is shown that our model reveals subtle changes in the behavior of the acoustic wave propagating quasi-modes.展开更多
A novel voltage-withstand substrate with high-K(HK, k > 3.9, k is the relative permittivity) dielectric and low specific on-resistance(Ron,sp) bulk-silicon, high-voltage LDMOS(HKLR LDMOS)is proposed in this paper. ...A novel voltage-withstand substrate with high-K(HK, k > 3.9, k is the relative permittivity) dielectric and low specific on-resistance(Ron,sp) bulk-silicon, high-voltage LDMOS(HKLR LDMOS)is proposed in this paper. The high-K dielectric and highly doped interface N+-layer are made in bulk silicon to reduce the surface field drift region. The high-K dielectric can fully assist in depleting the drift region to increase the drift doping concentration(Nd) and reshape the electric field distribution. The highly doped N+-layer under the high-K dielectric acts as a low resistance path to reduce the Ron,sp. The new device with the high breakdown voltage(BV), the low Ron,sp, and the excellent figure of merit(FOM = BV~2/Ron,sp) is obtained. The BV of HKLR LDMOS is 534 V, Ron,sp is 70.6 m?·cm~2, and FOM is 4.039 MW·cm~(-2).展开更多
Dear Editor,Bacteriophages are powerful tools for investigating and manipulating their hosts(Fernandes et al.,2014).This holds particularly true for mycobacteriophages,which have facilitated the development of mycobac...Dear Editor,Bacteriophages are powerful tools for investigating and manipulating their hosts(Fernandes et al.,2014).This holds particularly true for mycobacteriophages,which have facilitated the development of mycobacterial genetic systems and have generated tools for the clinical展开更多
The novel phage lysin PlySs2, is reported to be highly active against various bacteria, including staphylococci, streptococci and Listeria. However, the molecular mechanisms underlying its broad lytic spectrum remain ...The novel phage lysin PlySs2, is reported to be highly active against various bacteria, including staphylococci, streptococci and Listeria. However, the molecular mechanisms underlying its broad lytic spectrum remain to be established. In the present study, the lytic activity of the catalytic domain(CD, PlySc) and binding specificity of the cell wall binding domain(CBD, PlySb) of PlySs2 were examined. Our results showed that PlySc alone maintains very limited lytic activity. Enhanced green fluorescent protein(EGFP)-fused PlySb displayed high binding affinity to the streptococcal strains tested, including S.suis, S.dysgalactiae, and S.agalactiae, but not staphylococci, supporting its utility as a good CBD donor for streptococcal-targeted lysin engineering. EGFP-fused intact PlySs2 similarly displayed high affinity for streptococci, but not staphylococci. Notably, four truncated PlySb fragments showed no binding capacity. These findings collectively indicate that integrity of the PlySc and PlySb domains is an essential determinant of the broad lytic activity of PlySs2.展开更多
Personal credit risk assessment is an important part of the development of financial enterprises. Big data credit investigation is an inevitable trend of personal credit risk assessment, but some data are missing and ...Personal credit risk assessment is an important part of the development of financial enterprises. Big data credit investigation is an inevitable trend of personal credit risk assessment, but some data are missing and the amount of data is small, so it is difficult to train. At the same time, for different financial platforms, we need to use different models to train according to the characteristics of the current samples, which is time-consuming. <span style="font-family:Verdana;">In view of</span><span style="font-family:Verdana;"> these two problems, this paper uses the idea of transfer learning to build a transferable personal credit risk model based on Instance-based Transfer Learning (Instance-based TL). The model balances the weight of the samples in the source domain, and migrates the existing large dataset samples to the target domain of small samples, and finds out the commonness between them. At the same time, we have done a lot of experiments on the selection of base learners, including traditional machine learning algorithms and ensemble learning algorithms, such as decision tree, logistic regression, </span><span style="font-family:Verdana;">xgboost</span> <span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> so on. The datasets are from P2P platform and bank, the results show that the AUC value of Instance-based TL is 24% higher than that of the traditional machine learning model, which fully proves that the model in this paper has good application value. The model’s evaluation uses AUC, prediction, recall, F1. These criteria prove that this model has good application value from many aspects. At present, we are trying to apply this model to more fields to improve the robustness and applicability of the model;on the other hand, we are trying to do more in-depth research on domain adaptation to enrich the model.</span>展开更多
基金Supported by Strengthening Project of Science and Technology Commission Foundation under Grant No.2019JCJQZD。
文摘Due to the lack of surface dangling bonds in graphene,the direct growth of high-κ films via atomic layer deposition(ALD) technique often produces the dielectrics with a poor quality,which hinders its integration in modern semiconductor industry.Previous pretreatment approaches,such as chemical functionalization with ozone and plasma treatments,would inevitably degrade the quality of the underlying graphene.Here,we tackled this problem by utilizing an effective and convenient physical method.In detail,the graphene surface was pretreated with the deposition of thermally evaporated ultrathin Al metal layer prior to the Al2O3 growth by ALD.Then the device was placed in a drying oven for 30 min to be naturally oxidized as a seed layer.With the assistance of an Al oxide seed layer,pinhole-free Al2O3 dielectrics growth on graphene was achieved.No detective defects or disorders were introduced into graphene by Raman characterization.Moreover,our fabricated graphene topgated field effect transistor exhibited high mobility(~6200 cm2V-1s-1) and high transconductance(~117 μS).Thin dielectrics demonstrated a relative permittivity of 6.5 over a large area and a leakage current less than1.6 p A/μm2.These results indicate that Al oxide functionalization is a promising pathway to achieve scaled gate dielectrics on graphene with high performance.
基金Project supported by the National Natural Science Foundation of China(Grant No.11704399)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB21030300)the National Key Research and Development Program of China(Grant No.2017YFA0304402)。
文摘Accurate non-Born-Oppenheimer variational calculations of all bound states of the positive muon molecular ion 4Heμ^+ have been performed using explicitly correlated Gaussian functions in conjunction with the global vectors.All the energies obtained are accurate in the order of 10-6 Hartree(1 Hartree=27.2114 eV).Compared with the binding energies obtained from calculations based on the Born-Oppenheimer potential with the mass-weighted adiabatic corrections(Chem.Phys.Lett.110487(1984)),the largest relative deviation is up to 15%.By analyzing the average interparticle distances and possibility distributions of interparticle distances of this system,it is confirmed that the Born-Oppenheimer approximation is reasonable for this system and that 4Heμ^+ can be regarded as a system of positive muon bound to a slightly distorted helium atom.
文摘We analyze the transverse momentum dependence of HBT radii in relativistic heavy-ion collisions using several source models.Results indicate that the single-particle space-momentum angle distribution plays an important role in the transverse momentum dependence of HBT radii.In a cylinder source,we use several formulas to describe the transverse momentum dependence of HBT radii and the single-particle space-momentum angle distribution.We also make a numerical connection between them in the transverse plane.
文摘It is well known that the full compressible Navier-Stokes equations with viscosity and heat conductivity coefficients of order of the Knudsen number ò>0 can be deduced from the Boltzmann equation via the Chapman-Enskog expansion. In this paper, we carry out the rigorous mathematical study of the compressible Navier-Stokes equation with the initial-boundary value problems. We construct the existence and most importantly obtain the higher regularities of the solutions of the full compressible Navier-Stokes system with weak viscosity and heat conductivity in a general bounded domain.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11374066 and 11374068the High-Level Personnel Training Project in Guangdong Provincethe Natural Science Foundation of Guangdong Province under Grant No S2012020010885.
文摘We investigate the influence of coating layer on acoustic wave propagation in a dispersed random medium consisting of coa.ted fibers.In the strong-scattering regime, the characteristics of wave scattering resonances are found to evolve regularly with the properties of the coating layer.By theoretical calculation,frequency gaps are found in acoustic excitation spectra in a random medium.The scattering cross section results present the evolution of scattering resonances with the properties of the coating layer,which offers a good explanation for the change of the frequency gaps.The velocity of the propagation quasi-mode is also shown to depend on the filling fraction of the coating layer.We use the generalized coherent potential-approximation approach to solve acoustic wave dispersion relations in a complicated random medium consisting of coating-structure scatterers.It is shown that our model reveals subtle changes in the behavior of the acoustic wave propagating quasi-modes.
基金Project supported by the National Natural Science Foundation of China(Grant No.61306094) the Project of Hunan Provincial Education Department,China(Grant No.13ZA0089)+1 种基金 the Introduction of Talents Project of Changsha University of Science&Technology,China(Grant No.1198023) the Construct Program of the Key Discipline in Hunan Province,China
文摘A novel voltage-withstand substrate with high-K(HK, k > 3.9, k is the relative permittivity) dielectric and low specific on-resistance(Ron,sp) bulk-silicon, high-voltage LDMOS(HKLR LDMOS)is proposed in this paper. The high-K dielectric and highly doped interface N+-layer are made in bulk silicon to reduce the surface field drift region. The high-K dielectric can fully assist in depleting the drift region to increase the drift doping concentration(Nd) and reshape the electric field distribution. The highly doped N+-layer under the high-K dielectric acts as a low resistance path to reduce the Ron,sp. The new device with the high breakdown voltage(BV), the low Ron,sp, and the excellent figure of merit(FOM = BV~2/Ron,sp) is obtained. The BV of HKLR LDMOS is 534 V, Ron,sp is 70.6 m?·cm~2, and FOM is 4.039 MW·cm~(-2).
基金supported by a grant from the State Key Laboratory of Virology(PR China); Chinese Academy of Sciences(No.KJZD-EW-L02)
文摘Dear Editor,Bacteriophages are powerful tools for investigating and manipulating their hosts(Fernandes et al.,2014).This holds particularly true for mycobacteriophages,which have facilitated the development of mycobacterial genetic systems and have generated tools for the clinical
基金supported by the National Natural Science Foundation of China (No. 31400126); Basic Research Program of the Ministry of Science and Technology of China (No. 2012CB721102); Chinese Academy of Sciences (No. KJZD-EW-L02); Open Research Fund Program of the State Key Laboratory of Virology of China (No. 2014IOV002); Key Laboratory of Emerging Infectious Diseases and Biosafety, Wuhan
文摘The novel phage lysin PlySs2, is reported to be highly active against various bacteria, including staphylococci, streptococci and Listeria. However, the molecular mechanisms underlying its broad lytic spectrum remain to be established. In the present study, the lytic activity of the catalytic domain(CD, PlySc) and binding specificity of the cell wall binding domain(CBD, PlySb) of PlySs2 were examined. Our results showed that PlySc alone maintains very limited lytic activity. Enhanced green fluorescent protein(EGFP)-fused PlySb displayed high binding affinity to the streptococcal strains tested, including S.suis, S.dysgalactiae, and S.agalactiae, but not staphylococci, supporting its utility as a good CBD donor for streptococcal-targeted lysin engineering. EGFP-fused intact PlySs2 similarly displayed high affinity for streptococci, but not staphylococci. Notably, four truncated PlySb fragments showed no binding capacity. These findings collectively indicate that integrity of the PlySc and PlySb domains is an essential determinant of the broad lytic activity of PlySs2.
文摘Personal credit risk assessment is an important part of the development of financial enterprises. Big data credit investigation is an inevitable trend of personal credit risk assessment, but some data are missing and the amount of data is small, so it is difficult to train. At the same time, for different financial platforms, we need to use different models to train according to the characteristics of the current samples, which is time-consuming. <span style="font-family:Verdana;">In view of</span><span style="font-family:Verdana;"> these two problems, this paper uses the idea of transfer learning to build a transferable personal credit risk model based on Instance-based Transfer Learning (Instance-based TL). The model balances the weight of the samples in the source domain, and migrates the existing large dataset samples to the target domain of small samples, and finds out the commonness between them. At the same time, we have done a lot of experiments on the selection of base learners, including traditional machine learning algorithms and ensemble learning algorithms, such as decision tree, logistic regression, </span><span style="font-family:Verdana;">xgboost</span> <span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> so on. The datasets are from P2P platform and bank, the results show that the AUC value of Instance-based TL is 24% higher than that of the traditional machine learning model, which fully proves that the model in this paper has good application value. The model’s evaluation uses AUC, prediction, recall, F1. These criteria prove that this model has good application value from many aspects. At present, we are trying to apply this model to more fields to improve the robustness and applicability of the model;on the other hand, we are trying to do more in-depth research on domain adaptation to enrich the model.</span>