We develop a novel coumarin-all〈yne derivative （NC7-AL）, which can specifically react with Au^3＋ and give a colorimetric and fluorescent ＂turn-on＂ response toward Au3~, Notably, other alkynophilic metal species ...We develop a novel coumarin-all〈yne derivative （NC7-AL）, which can specifically react with Au^3＋ and give a colorimetric and fluorescent ＂turn-on＂ response toward Au3~, Notably, other alkynophilic metal species such as Au^＋, Ag^＋, Pd^2＋, Ni^2＋, Cu^2＋, and Hg^2＋ do not produce an interfering signal. A good linear relationship between emission intensity at 420 nm and Au^3＋ concentration from 0 to 2 equivalent is observed, and the detection limit （3σ/k） is estimated to be ca. 3.58 nmol/L. Harnessing the Au^3＋ .展开更多
The ionization potential （IP） is a basic property of an atom, which has many applications such as in element analysis. With the Dirac-Slater methods （i.e., mean field theory）, IPs of all occupied orbitals for elem...The ionization potential （IP） is a basic property of an atom, which has many applications such as in element analysis. With the Dirac-Slater methods （i.e., mean field theory）, IPs of all occupied orbitals for elements with atomic number （Z ≤ 119） are calculated conveniently and systematically. Compared with available experimental measurements, the theoretical accuracies of IPs for various occupied orbitals are ascertained. The map of the inner orbital IPs with Mood accuracies should be useful to select x-ray energies for element analysis. Based on systematic variations of the first IPs for the outermost orbitals in good agreement with experimental values as well as other IPs, mechanisms of electronic configurations of all atomic elements （Z ≤ 119） along the periodic table are elucidated. It is interesting to note that there exist some deficiencies of the intermediate orbital IPs, which are due to electron correlations and should be treated beyond the mean field theory.展开更多
Based on relativistic channel theory, we have studied the fine structures of n^(2)D Rydberg states for alkali atoms. We explain the abnormal fine structures owing to the competition effect of the spin-orbit interactio...Based on relativistic channel theory, we have studied the fine structures of n^(2)D Rydberg states for alkali atoms. We explain the abnormal fine structures owing to the competition effect of the spin-orbit interaction and the relativistic effect of the exchange interactions between the excited electron and the core electrons.展开更多
The electron-ion scattering processes are very important in various scientific research fields such as astrophysical studies and inertial confinement fusion research.We report our recent development of an efficient me...The electron-ion scattering processes are very important in various scientific research fields such as astrophysical studies and inertial confinement fusion research.We report our recent development of an efficient method for providing such atomic data with spectroscopic precision.Based on the Breit-Pauli and the Dirac R-matrix theory,we develop two eigenchannel R-matrix codes,referred to as R-eigen(non-relelativistic eigenchannel R-matrix)and R-R-eigen(relativistic eigenchannel R-matrix),to directly calculate the physical quantities in multichannel quantum defect theory in the whole energy regions.From such physical quantities,we can obtain all energy levels and the related scattering cross sections with accuracies comparable with spectroscopic precision.The e+Kr+system is used as an illustration example,the degrees of accuracies of scattering matrices are calculated within about 2%,which should be much more accurate than state-of-the-art scattering experiments.展开更多
Scientific research fields for future energies such as inertial confinement fusion researches and astrophysics studies especially with satellite observatories advance into stages of precision physics.The relevant atom...Scientific research fields for future energies such as inertial confinement fusion researches and astrophysics studies especially with satellite observatories advance into stages of precision physics.The relevant atomic data are not only enormous but also of accuracy according to requirements,especially for both energy levels and the collision data.The fine structure of high excited states of atoms and ions can be measured by precision spectroscopy.Such precision measurements can provide not only knowledge about detailed dynamics of electron-ion interactions but also a bench mark examination of the accuracy of electron-ion collision data,especially incorporating theoretical computations.We illustrate that by using theoretical calculation methods which can treat the bound states and the adjacent continua on equal footing.The precision spectroscopic measurements of excited fine structures can be served as stringent tests of electron-ion collision data.展开更多
Piper (1944) diagram has been the basis for several important interpretations of the hydrogeochemical data. As seen in this diagram, most natural waters contain relatively few dissolved constituents, with cations (met...Piper (1944) diagram has been the basis for several important interpretations of the hydrogeochemical data. As seen in this diagram, most natural waters contain relatively few dissolved constituents, with cations (metals or bases) and anions (acid radicles) in chemical equilibrium with one another. Apart from the facies representation, the composition of the mixed sample can be identified in terms of the composition of the parental solution. To bring out this advantage of the Piper diagram, a study was conducted in the Kalpakkam region of Tamilnadu, South India. By taking the geology and water table into consideration, two sample locations were selected as parent solution and third one as the mixture sample. All three samples were analyzed for calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), chloride (Cl), sulphate (SO4) and phosphate (PO4) by Ion Chromatograph (Metrohm IC 861). HCO3 was determined by volumetric titration. The Piper diagram shows that parent solutions clustered towards Na-Mg-Ca-HCO3-Cl and Na-HCO3 facies, and the mixing sample belongs to Na-Mg-HCO3 facies. Phreeqc interac-tive (Ver 2.8) along with the original composition of the mixture sample was used to correlate the mixing proportion identified by the Piper diagram.展开更多
Mitochondria and lysosomes are essential cellular organelles in most eukaryotic cells by playing the physiological roles to support the normal functions of cells, as well as the life of the whole body. To date,small-m...Mitochondria and lysosomes are essential cellular organelles in most eukaryotic cells by playing the physiological roles to support the normal functions of cells, as well as the life of the whole body. To date,small-molecule fluorescent probes have been considered as one of the vital tools for monitoring and visualizing multiple biological analytes. This review summarized the recent advances in small-molecule two-photon fluorescent probes for metal ions, reactive oxygen species（ROS） and reactive sulfur species（RSS）, and changes inside micro-environment（e.g., p H, viscosity and polarity） in mitochondria and lysosomes, or served as mitotracker and lysotracker with the assistance of two-photon microscopy.展开更多
The armour grade quenched and tempered steel joints fabricated using low hydrogen ferritic steel （LHF） filler exhibited superior joint efficiency owing to preferential ferrite microstructure in the welds and also th...The armour grade quenched and tempered steel joints fabricated using low hydrogen ferritic steel （LHF） filler exhibited superior joint efficiency owing to preferential ferrite microstructure in the welds and also they offered required resistance to HIC. However, the combat vehicles used in military operations will be required to operate under a wide range of road conditions ranging from first class to cross country. Structural components in combat vehicles are subjected to dynamic loading with high strain rates during operation. Stress loadings within the vehicle hull of these vehicles are expected to fluctuate considerably and structural cracking especially in welds during the service life of these vehicles can lead to catastrophic failures. Under these conditions, fracture behaviour of high strain rate sensitive structural steels can be better understood by dynamic fracture toughness （K1d）. Hence, an attempt was made to study dynamic fracture toughness of the armour grade quenched and tempered steel and their welds fabricated using LHF consumables. The experimental results indicate that the K1d values of the joints fabricated by shielded metal arc welding （SMAW） are higher than those of the joints fabricated using flux cored arc welding （FCAW） process.展开更多
Two kinds of M-particle d-dimensional Schmidt-form entangled state teleportation protocols are presented.In the first protocol, the teleportation is achieved by d-dimensional Bell-basis measurements, while in the seco...Two kinds of M-particle d-dimensional Schmidt-form entangled state teleportation protocols are presented.In the first protocol, the teleportation is achieved by d-dimensional Bell-basis measurements, while in the second protocolit is realized by d-dimensional GHZ-basis measurement.展开更多
The electonic transition rates in low-energy ion-surface interaction were studied by emplaying tilted-foil and grazing incidence geometries, and the linear and circular polarizations of light emitted were observed, re...The electonic transition rates in low-energy ion-surface interaction were studied by emplaying tilted-foil and grazing incidence geometries, and the linear and circular polarizations of light emitted were observed, respectively. The theoretical understanding of the dynamics is still expected.展开更多
Using the multi-configuration Dirac-Fock self-consistent field method and the relativistic configuration-interaction method, calculations of transition energies, oscillator strengths and rates are performed for the 3s...Using the multi-configuration Dirac-Fock self-consistent field method and the relativistic configuration-interaction method, calculations of transition energies, oscillator strengths and rates are performed for the 3s2 1S0-3s3p 1P1 spinallowed transition, 3s2 1S0-3s3p 3P1,2 intercombination and magnetic quadrupole transition in the Mg isoelectronic sequence （Mg I, A1 II, Si III, P IV and S V）. Electron correlations are treated adequately, including intravalence electron correlations. The influence of the Breit interaction on oscillator strengths and transition energies are investigated. Quantum eleetrodynamics corrections are added as corrections. The calculation results are found to be in good agreement with the experimental data and other theoretical calculations.展开更多
Bimetallic nanocluster with atomic precision has gained widespread attention due to its unique synergism.The coreless Au_(4)Cu_(5)bimetallic nanoclusters were selected as models to explore the relationship between the...Bimetallic nanocluster with atomic precision has gained widespread attention due to its unique synergism.The coreless Au_(4)Cu_(5)bimetallic nanoclusters were selected as models to explore the relationship between their microstructure and performance,and compare with the coreless monometallic nanoclusters,core–shell nanoclusters,and single atom catalyst(SAC).The experimental results show that the coreless bimetallic nanocluster catalyst Au_(4)Cu_(5)/activated carbon(AC)exhibits high activity and stability in the Ullmann C–O coupling reaction,much higher than coreless monometallic nanoclusters(Au_(11)/AC and Cu_(11)/AC),core–shell nanoclusters(Au_(25)/AC,Cu_(25)/AC,and Au_(1)Cu_(24)/AC),and single atom catalysts(Au SAC and Cu SAC).Moreover,the coreless Au_(4)Cu_(5)/AC catalyst efficiently catalyzed the Ullmann C–O coupling of benzyl alcohol for the first time.This structure–activity relationship was successfully extended to other coreless bimetallic systems,such as Au_(4)Cu_(4)/AC nanocluster,and it is expected to provide new insights for the design of bimetallic catalysts with well-defined performance.展开更多
Diamond particle dispersed copper (Cu) matrix composites were fabricated from the powder mixture composed of diamond, pure-Cu and boron (B) by spark plasma sintering (SPS). The composites were consolidated at 1173 K f...Diamond particle dispersed copper (Cu) matrix composites were fabricated from the powder mixture composed of diamond, pure-Cu and boron (B) by spark plasma sintering (SPS). The composites were consolidated at 1173 K for 600 s by SPS. The reaction between the diamond particle and the Cu matrix in the composite was not confirmed by SEM observation and X-ray diffraction (XRD) analysis. The relative packing density of the Cu/diamond composites increased with B addition and attained 93.2% - 95.8% at the B content range between 1.8 vol.% and 13.8 vol.%. The thermal conductivity of the diamond-dispersed Cu composite drastically increased with B addition and reached the maximum value of 689 W/mK at 7.2 vol% B. Numerous transgranular fractures of diamond particles were observed on bending fracture surfaces of Cu-B/diamond composites. This indicates strong bonding between the diamond particle and the Cu matrix in the composite. The coefficient of thermal expansion of the composite falls in the upper line of Kerner’s model.展开更多
The quantum nature of bulk ensemble NMR quantum computing the center of recent heated debate,is addressed. Concepts of the mixed state and entanglement are examined, and the data in a two-qubit liquid NMRquantum compu...The quantum nature of bulk ensemble NMR quantum computing the center of recent heated debate,is addressed. Concepts of the mixed state and entanglement are examined, and the data in a two-qubit liquid NMRquantum computation are analyzed. The main points in this paper are: i) Density matrix describes the "state" of anaverage particle in an ensemble. It does not describe the state of an individual particle in an ensemble; ii) Entanglementis a property of the wave function of a microscopic particle (such as a molecule in a liquid NMR sample), and separabilityof the density matrix cannot be used to measure the entanglement of mixed ensemble; iii) The state evolution in bulk-ensemble NMRquantum computation is quantum-mechanical; iv) The coefficient before the effective pure state densitymatrix, e, is a measure of the simultaneity of the molecules in an ensemble. It reflects the intensity of the NMR signaland has no significance in quantifying the entanglement in the bulk ensemble NMR system. The decomposition of thedensity matrix into product states is only an indication that the ensemble can be prepared by an ensemble with theparticles unentangled. We conclude that effective-pure-state NMR quantum computation is genuine, not just classicalsimulations.展开更多
Based on the results of the optimum metallic-bond scheme for sodium clusters, we present a quantitative analysis of the detailed features of the mass spectra of sodium clusters. We find that, in the generation of sodi...Based on the results of the optimum metallic-bond scheme for sodium clusters, we present a quantitative analysis of the detailed features of the mass spectra of sodium clusters. We find that, in the generation of sodium clusters with various abundances, the quasi-steady processes through adding or losing a sodium atom dominate. The quasi-steady processes through adding or losing a sodium dimer are also important to understand the detailed features of mass spectra for small clusters.展开更多
A method to deal with the electron impact excitation cross sections of an atom from low to high incident energies are presented. This method combines the partial wave method and the first Born approximation(FBA), i.e....A method to deal with the electron impact excitation cross sections of an atom from low to high incident energies are presented. This method combines the partial wave method and the first Born approximation(FBA), i.e., replacing the several lowest partial wave cross sections of the total cross sections within FBA by the corresponding exact partial wave cross sections. A new set of codes are developed to calculate the FBA partial wave cross sections. Using this method,the convergent e–He collision cross sections of optical-forbidden and optical-allowed transitions at low to high incident energies are obtained. The calculation results demonstrate the validity and efficiency of the method.展开更多
We present a nonlinear theory of light velocity reduction in a three-levelΛsystem based on electromagnetically induced transparency.Analysis shows that probe field propagates with a velocity that is quite strongly de...We present a nonlinear theory of light velocity reduction in a three-levelΛsystem based on electromagnetically induced transparency.Analysis shows that probe field propagates with a velocity that is quite strongly dependent on its intensity instead of being merely approximately dependent on the coupling intensity.Moreover,the minimum group velocity of the probe field is analytically given for a given input power.展开更多
The electron impact excitation(EIE) cross sections of an atom/ion in the whole energy region are needed in many research fields, such as astrophysics studies, inertial confinement fusion researches and so on. In the p...The electron impact excitation(EIE) cross sections of an atom/ion in the whole energy region are needed in many research fields, such as astrophysics studies, inertial confinement fusion researches and so on. In the present work, an effective method to calculate the EIE cross sections of an atom/ion in the whole energy region is presented. We use the EIE cross sections of helium as an illustration example. The optical forbidden 1^(1)S–n^(1)S(n = 2–4) and optical allowed 1^(1)S–n^(1)P(n = 2–4) excitation cross sections are calculated in the whole energy region using the scheme that combines the partial wave R-matrix method and the first Born approximation. The calculated cross sections are in good agreement with the available experimental measurements. Based on these accurate cross sections of our calculation, we find that the ratios between the accurate cross sections and Born cross sections are nearly the same for different excitation final states in the same channel. According to this interesting property, a universal correction function is proposed and given to calculate the accurate EIE cross sections with the same computational efforts of the widely used Born cross sections,which should be very useful in the related application fields. The datasets presented in this paper are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00142.展开更多
Carbon nanotubes with finite lengths should be natural components of future“nano devices”.Based on orthogonal tight-binding molecular dynamics simulations,we report our study of formation energies,optimal geometrica...Carbon nanotubes with finite lengths should be natural components of future“nano devices”.Based on orthogonal tight-binding molecular dynamics simulations,we report our study of formation energies,optimal geometrical structures and active sites of carbon nanotubes with finite lengths.This should be useful to understand the properties of such natural components.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 21102001, 21271035 and 21372005)Anhui Provincial Natural Science Foundation (No. 1608085MB39)+1 种基金Natural Science Foundation of Education Department of Anhui Province (Nos. KJ2015A047, KJ2014A013)211 Project of Anhui University
文摘We develop a novel coumarin-all〈yne derivative （NC7-AL）, which can specifically react with Au^3＋ and give a colorimetric and fluorescent ＂turn-on＂ response toward Au3~, Notably, other alkynophilic metal species such as Au^＋, Ag^＋, Pd^2＋, Ni^2＋, Cu^2＋, and Hg^2＋ do not produce an interfering signal. A good linear relationship between emission intensity at 420 nm and Au^3＋ concentration from 0 to 2 equivalent is observed, and the detection limit （3σ/k） is estimated to be ca. 3.58 nmol/L. Harnessing the Au^3＋ .
基金Supported by the Ministry of Science and Technology and Ministry of Education of Chinathe Key Grant Project of Chinese Ministry of Education under Grant No 306020+2 种基金the National Natural Science Foundation of China under Grant Nos 11274035 and 11328401the National High-Tech ICF Committee in China,the Yin-He Super-computer Center,Institute of Applied Physics and Mathematicsthe National Basic Research Program of China under Grant No 2011CB921501
文摘The ionization potential （IP） is a basic property of an atom, which has many applications such as in element analysis. With the Dirac-Slater methods （i.e., mean field theory）, IPs of all occupied orbitals for elements with atomic number （Z ≤ 119） are calculated conveniently and systematically. Compared with available experimental measurements, the theoretical accuracies of IPs for various occupied orbitals are ascertained. The map of the inner orbital IPs with Mood accuracies should be useful to select x-ray energies for element analysis. Based on systematic variations of the first IPs for the outermost orbitals in good agreement with experimental values as well as other IPs, mechanisms of electronic configurations of all atomic elements （Z ≤ 119） along the periodic table are elucidated. It is interesting to note that there exist some deficiencies of the intermediate orbital IPs, which are due to electron correlations and should be treated beyond the mean field theory.
基金Supported in part by National High-Tech ICF Commit tee in Chinathe National Natural Science Foundation of China under Grant No.19734003the Ministry of Science and Technology and the Ministry of Education,PRC.
文摘Based on relativistic channel theory, we have studied the fine structures of n^(2)D Rydberg states for alkali atoms. We explain the abnormal fine structures owing to the competition effect of the spin-orbit interaction and the relativistic effect of the exchange interactions between the excited electron and the core electrons.
基金Supported by the Ministry of Science and Technology and Ministry of Education of China,the Key Project of the Ministry of Education of China(No 306020)the National Natural Science Foundation of China under Grant No 10734040+1 种基金the National High-Tech ICF Committee in China and the Yin-He Super-computer Center,Institute of Applied Physics and Mathematics,Beijing,Chinathe National Basic Research Program of China under Grant Nos 2010CB922900 and 2011CB921501.
文摘The electron-ion scattering processes are very important in various scientific research fields such as astrophysical studies and inertial confinement fusion research.We report our recent development of an efficient method for providing such atomic data with spectroscopic precision.Based on the Breit-Pauli and the Dirac R-matrix theory,we develop two eigenchannel R-matrix codes,referred to as R-eigen(non-relelativistic eigenchannel R-matrix)and R-R-eigen(relativistic eigenchannel R-matrix),to directly calculate the physical quantities in multichannel quantum defect theory in the whole energy regions.From such physical quantities,we can obtain all energy levels and the related scattering cross sections with accuracies comparable with spectroscopic precision.The e+Kr+system is used as an illustration example,the degrees of accuracies of scattering matrices are calculated within about 2%,which should be much more accurate than state-of-the-art scattering experiments.
基金Supported by the Ministry of Science and Technology and Ministry of Education of China,the Key Project of the Ministry of Education of China(No 306020)the National Natural Science Foundation of China(Nos 10734040 and 10905040)the National High-Tech ICF Committee in China,the Yin-He Super-computer Center,Institute of Applied Physics and Mathematics,Beijing,China,and the National Basic Research Program of China(Nos 2010CB922900 and 2011CB921501).
文摘Scientific research fields for future energies such as inertial confinement fusion researches and astrophysics studies especially with satellite observatories advance into stages of precision physics.The relevant atomic data are not only enormous but also of accuracy according to requirements,especially for both energy levels and the collision data.The fine structure of high excited states of atoms and ions can be measured by precision spectroscopy.Such precision measurements can provide not only knowledge about detailed dynamics of electron-ion interactions but also a bench mark examination of the accuracy of electron-ion collision data,especially incorporating theoretical computations.We illustrate that by using theoretical calculation methods which can treat the bound states and the adjacent continua on equal footing.The precision spectroscopic measurements of excited fine structures can be served as stringent tests of electron-ion collision data.
文摘Piper (1944) diagram has been the basis for several important interpretations of the hydrogeochemical data. As seen in this diagram, most natural waters contain relatively few dissolved constituents, with cations (metals or bases) and anions (acid radicles) in chemical equilibrium with one another. Apart from the facies representation, the composition of the mixed sample can be identified in terms of the composition of the parental solution. To bring out this advantage of the Piper diagram, a study was conducted in the Kalpakkam region of Tamilnadu, South India. By taking the geology and water table into consideration, two sample locations were selected as parent solution and third one as the mixture sample. All three samples were analyzed for calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), chloride (Cl), sulphate (SO4) and phosphate (PO4) by Ion Chromatograph (Metrohm IC 861). HCO3 was determined by volumetric titration. The Piper diagram shows that parent solutions clustered towards Na-Mg-Ca-HCO3-Cl and Na-HCO3 facies, and the mixing sample belongs to Na-Mg-HCO3 facies. Phreeqc interac-tive (Ver 2.8) along with the original composition of the mixture sample was used to correlate the mixing proportion identified by the Piper diagram.
基金supported by the National Natural Science Foundation of China (Nos. 21778001, 21372005)the Anhui Provincial Natural Science Foundation (No. 1608085MB39)+1 种基金the Natural Science Foundation of Education Department of Anhui Province (No. KJ2015A047)the 211 Project of Anhui University
文摘Mitochondria and lysosomes are essential cellular organelles in most eukaryotic cells by playing the physiological roles to support the normal functions of cells, as well as the life of the whole body. To date,small-molecule fluorescent probes have been considered as one of the vital tools for monitoring and visualizing multiple biological analytes. This review summarized the recent advances in small-molecule two-photon fluorescent probes for metal ions, reactive oxygen species（ROS） and reactive sulfur species（RSS）, and changes inside micro-environment（e.g., p H, viscosity and polarity） in mitochondria and lysosomes, or served as mitotracker and lysotracker with the assistance of two-photon microscopy.
基金Armament Research Board (ARMREB),New Delhi for funding this project work (Project No MAA/03/41)
文摘The armour grade quenched and tempered steel joints fabricated using low hydrogen ferritic steel （LHF） filler exhibited superior joint efficiency owing to preferential ferrite microstructure in the welds and also they offered required resistance to HIC. However, the combat vehicles used in military operations will be required to operate under a wide range of road conditions ranging from first class to cross country. Structural components in combat vehicles are subjected to dynamic loading with high strain rates during operation. Stress loadings within the vehicle hull of these vehicles are expected to fluctuate considerably and structural cracking especially in welds during the service life of these vehicles can lead to catastrophic failures. Under these conditions, fracture behaviour of high strain rate sensitive structural steels can be better understood by dynamic fracture toughness （K1d）. Hence, an attempt was made to study dynamic fracture toughness of the armour grade quenched and tempered steel and their welds fabricated using LHF consumables. The experimental results indicate that the K1d values of the joints fabricated by shielded metal arc welding （SMAW） are higher than those of the joints fabricated using flux cored arc welding （FCAW） process.
基金The project supported by the Major State Basic Research Development Program under Grant No. G200077400, National NaturalScience Foundation of China under Grant No. 60073009, the Fok Ying Tung Education Foundation, and the Excellent Young UniversityTeachers' Fund of Education Ministry of China
文摘Two kinds of M-particle d-dimensional Schmidt-form entangled state teleportation protocols are presented.In the first protocol, the teleportation is achieved by d-dimensional Bell-basis measurements, while in the second protocolit is realized by d-dimensional GHZ-basis measurement.
文摘The electonic transition rates in low-energy ion-surface interaction were studied by emplaying tilted-foil and grazing incidence geometries, and the linear and circular polarizations of light emitted were observed, respectively. The theoretical understanding of the dynamics is still expected.
基金supported by the Key Program of Science and Technology Research of Ministry of Education of China (Grant No. 306020)the National Natural Science Foundation of China (Grant Nos. 10905040 and 10734040)+2 种基金the National High-Tech ICF Committee in Chinathe Yin-He Super-computer Center,Institute of Applied Physics and Mathematics,Beijing,Chinathe National Basic Research Program of China (Grant Nos. 2010CB922900 and 2011CB921501)
文摘Using the multi-configuration Dirac-Fock self-consistent field method and the relativistic configuration-interaction method, calculations of transition energies, oscillator strengths and rates are performed for the 3s2 1S0-3s3p 1P1 spinallowed transition, 3s2 1S0-3s3p 3P1,2 intercombination and magnetic quadrupole transition in the Mg isoelectronic sequence （Mg I, A1 II, Si III, P IV and S V）. Electron correlations are treated adequately, including intravalence electron correlations. The influence of the Breit interaction on oscillator strengths and transition energies are investigated. Quantum eleetrodynamics corrections are added as corrections. The calculation results are found to be in good agreement with the experimental data and other theoretical calculations.
基金We acknowledge financial support by the National Natural Science Foundation of China(Nos.21972001 and 21871001)Natural Science Foundation of Anhui Province(No.2008085MB37)Anhui University.
文摘Bimetallic nanocluster with atomic precision has gained widespread attention due to its unique synergism.The coreless Au_(4)Cu_(5)bimetallic nanoclusters were selected as models to explore the relationship between their microstructure and performance,and compare with the coreless monometallic nanoclusters,core–shell nanoclusters,and single atom catalyst(SAC).The experimental results show that the coreless bimetallic nanocluster catalyst Au_(4)Cu_(5)/activated carbon(AC)exhibits high activity and stability in the Ullmann C–O coupling reaction,much higher than coreless monometallic nanoclusters(Au_(11)/AC and Cu_(11)/AC),core–shell nanoclusters(Au_(25)/AC,Cu_(25)/AC,and Au_(1)Cu_(24)/AC),and single atom catalysts(Au SAC and Cu SAC).Moreover,the coreless Au_(4)Cu_(5)/AC catalyst efficiently catalyzed the Ullmann C–O coupling of benzyl alcohol for the first time.This structure–activity relationship was successfully extended to other coreless bimetallic systems,such as Au_(4)Cu_(4)/AC nanocluster,and it is expected to provide new insights for the design of bimetallic catalysts with well-defined performance.
文摘Diamond particle dispersed copper (Cu) matrix composites were fabricated from the powder mixture composed of diamond, pure-Cu and boron (B) by spark plasma sintering (SPS). The composites were consolidated at 1173 K for 600 s by SPS. The reaction between the diamond particle and the Cu matrix in the composite was not confirmed by SEM observation and X-ray diffraction (XRD) analysis. The relative packing density of the Cu/diamond composites increased with B addition and attained 93.2% - 95.8% at the B content range between 1.8 vol.% and 13.8 vol.%. The thermal conductivity of the diamond-dispersed Cu composite drastically increased with B addition and reached the maximum value of 689 W/mK at 7.2 vol% B. Numerous transgranular fractures of diamond particles were observed on bending fracture surfaces of Cu-B/diamond composites. This indicates strong bonding between the diamond particle and the Cu matrix in the composite. The coefficient of thermal expansion of the composite falls in the upper line of Kerner’s model.
基金The project supported by National Fundamental Research Program under Grant No. 001CB309308, and National Natural Science Foundation of China under Grant No. 60073009, the Hang Tian Science Fund, and the Excellent Young University Teachers' Fund of the Education Ministry of Chnia
文摘The quantum nature of bulk ensemble NMR quantum computing the center of recent heated debate,is addressed. Concepts of the mixed state and entanglement are examined, and the data in a two-qubit liquid NMRquantum computation are analyzed. The main points in this paper are: i) Density matrix describes the "state" of anaverage particle in an ensemble. It does not describe the state of an individual particle in an ensemble; ii) Entanglementis a property of the wave function of a microscopic particle (such as a molecule in a liquid NMR sample), and separabilityof the density matrix cannot be used to measure the entanglement of mixed ensemble; iii) The state evolution in bulk-ensemble NMRquantum computation is quantum-mechanical; iv) The coefficient before the effective pure state densitymatrix, e, is a measure of the simultaneity of the molecules in an ensemble. It reflects the intensity of the NMR signaland has no significance in quantifying the entanglement in the bulk ensemble NMR system. The decomposition of thedensity matrix into product states is only an indication that the ensemble can be prepared by an ensemble with theparticles unentangled. We conclude that effective-pure-state NMR quantum computation is genuine, not just classicalsimulations.
基金the National Natural Science Foundation of China，the Natural Science Foundation of Anhui University，the Doctor Research Foundation of Anhui University
基金Supported partially by the National Natural Science Foundation of China under Grant No.19734003the National High-Tech ICF Committee in China,Ministry of Science and Technology and the Ministry of Education of China.
文摘Based on the results of the optimum metallic-bond scheme for sodium clusters, we present a quantitative analysis of the detailed features of the mass spectra of sodium clusters. We find that, in the generation of sodium clusters with various abundances, the quasi-steady processes through adding or losing a sodium atom dominate. The quasi-steady processes through adding or losing a sodium dimer are also important to understand the detailed features of mass spectra for small clusters.
基金supported by the National Basic Research Program of China(Grant Nos.2011CB921501 and 2013CB922200)the National Natural Science Foundation of China(Grant Nos.11274035,11275029,11328401,11371218,11474031,11474032,and 11474034)the Foundation of Development of Science and Technology of Chinese Academy of Engineering Physics(Grant Nos.2013A0102005 and 2014A0102005)
文摘A method to deal with the electron impact excitation cross sections of an atom from low to high incident energies are presented. This method combines the partial wave method and the first Born approximation(FBA), i.e., replacing the several lowest partial wave cross sections of the total cross sections within FBA by the corresponding exact partial wave cross sections. A new set of codes are developed to calculate the FBA partial wave cross sections. Using this method,the convergent e–He collision cross sections of optical-forbidden and optical-allowed transitions at low to high incident energies are obtained. The calculation results demonstrate the validity and efficiency of the method.
基金Supported in part by the National Natural Science Foundation of China under Grant Nos.19834060 and 19975027.
文摘We present a nonlinear theory of light velocity reduction in a three-levelΛsystem based on electromagnetically induced transparency.Analysis shows that probe field propagates with a velocity that is quite strongly dependent on its intensity instead of being merely approximately dependent on the coupling intensity.Moreover,the minimum group velocity of the probe field is analytically given for a given input power.
基金Project supported by the National Natural Science Foundation of China (Grant No. 12241410)。
文摘The electron impact excitation(EIE) cross sections of an atom/ion in the whole energy region are needed in many research fields, such as astrophysics studies, inertial confinement fusion researches and so on. In the present work, an effective method to calculate the EIE cross sections of an atom/ion in the whole energy region is presented. We use the EIE cross sections of helium as an illustration example. The optical forbidden 1^(1)S–n^(1)S(n = 2–4) and optical allowed 1^(1)S–n^(1)P(n = 2–4) excitation cross sections are calculated in the whole energy region using the scheme that combines the partial wave R-matrix method and the first Born approximation. The calculated cross sections are in good agreement with the available experimental measurements. Based on these accurate cross sections of our calculation, we find that the ratios between the accurate cross sections and Born cross sections are nearly the same for different excitation final states in the same channel. According to this interesting property, a universal correction function is proposed and given to calculate the accurate EIE cross sections with the same computational efforts of the widely used Born cross sections,which should be very useful in the related application fields. The datasets presented in this paper are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00142.
基金Supported in part by Ministry of Education,PRC,the National PAN-DENG Project(95-YU-41)the National Natural Science Foundation of China under Grant No.69876035National High-Tech ICF Committee in China.
文摘Carbon nanotubes with finite lengths should be natural components of future“nano devices”.Based on orthogonal tight-binding molecular dynamics simulations,we report our study of formation energies,optimal geometrical structures and active sites of carbon nanotubes with finite lengths.This should be useful to understand the properties of such natural components.
