In random-interaction ensembles, the electric quadrupole moments(Q) and magnetic moments(μ) of the Iπ = 11/2-isomers of the Cd isotopes predominantly exhibit a linear correlation with the neutron numbers,correspondi...In random-interaction ensembles, the electric quadrupole moments(Q) and magnetic moments(μ) of the Iπ = 11/2-isomers of the Cd isotopes predominantly exhibit a linear correlation with the neutron numbers,corresponding to the recently emphasized linear Q and μsystematics in realistic nuclear systems. Although the seniority scheme enhances such predominance(more essentially for μ), the configuration mixing due to quadrupole-like and δ-force-like proton-neutron(pn) interactions is responsible for the linear Q and μ systematics,respectively, in realistic nuclear system, as well as randominteraction ensembles.展开更多
We calculated the structural, elastic, and electronic properties of alkali metal Na atoms doped type-I silicon-clathrate compound（Na8Si46） under pressure using first-principles methods. The obtained dependencies of ...We calculated the structural, elastic, and electronic properties of alkali metal Na atoms doped type-I silicon-clathrate compound（Na8Si46） under pressure using first-principles methods. The obtained dependencies of bond lengths and bond angles on pressure show heterogeneous behaviors which may bring out a structural transition. By using the elastic stability criteria from the calculated elastic constants, we confirm that the Na8Si46 is elastically unstable under high pressure. Some of the mechanical and thermal quantities include bulk modulus, shear modulus,Young＇s modulus, Debye temperature,sound velocity, melting point, and hardness, which are also derived from the elastic constants. The calculated total and partial electron densities of states of Na8Si46 indicate a weak interaction between the encapsulated Na atoms and the silicon framework. Moreover, the effect of pressure on its electronic structure is also investigated, which suggests that pressure is not a good choice to enhance the thermoelectricity performance of Na8Si46.展开更多
Helium effects on dislocation and cavity formation of Fe-11 wt.% Cr model alloy are investigated. Single-beam(electron) and dual-beam(He^+/e^-) irradiations are performed at 350℃ and 400℃ using an ultra-high voltage...Helium effects on dislocation and cavity formation of Fe-11 wt.% Cr model alloy are investigated. Single-beam(electron) and dual-beam(He^+/e^-) irradiations are performed at 350℃ and 400℃ using an ultra-high voltage electron microscope combined with ion accelerators. In-situ observation shows that the growth rate of dislocation loops is reduced in the helium pre-injected specimen. The mean size of cavities decreased in the helium preinjected specimen. The possible mechanisms are discussed.展开更多
To address the hazardous by-product of zinc smelting and resource utilization of jarosite residue,this study applies an electric field-assisted hot acid treatment to completely recycle iron(Fe).This innovative approac...To address the hazardous by-product of zinc smelting and resource utilization of jarosite residue,this study applies an electric field-assisted hot acid treatment to completely recycle iron(Fe).This innovative approach aims to enhance the leaching efficiency of Fe from jarosite residue.The introduction of an electric field changes the charge distribution on the surface of the particles to enhance ions and electrons exchange and promotes the collision between particles to strengthen reaction kinetics.Based on the above,the leaching efficiency of Fe in jarosite under sulfuric acid attack has improved observably.The result shows that Fe leaching efficiency reaches 98.83%,which is increased by 28%under the optimal experimental conditions:current density of 30 mA·cm^(-2),H_(2)SO_(4) concentration of 1.5 mol·L^(-1),solid-liquid ratio of 70 g·L^(-1),temperature of 80℃ and time of 12 h.Leaching kinetics calculations show that the apparent activation energy is 16.97 kJ·mol^(-1) and the leaching of jarosite residue is controlled by a mixture of chemical reaction and diffusion,as well as the temperature and concentration of the leaching solution have an influence on leaching.This work provides a feasible idea for the efficient leaching of Fe from jarosite residue.展开更多
Surface chemistry modification represents a promising strategy to tailor the adsorption and activation of reaction intermediates for enhancing activity.Herein,we designed a surface oxygen-injection strategy to tune th...Surface chemistry modification represents a promising strategy to tailor the adsorption and activation of reaction intermediates for enhancing activity.Herein,we designed a surface oxygen-injection strategy to tune the electronic structure of SnS_(2) nanosheets,which showed effectively enhanced electrocatalytic activity and selectivity of CO_(2) reduction to formate and syngas(CO and H_(2)).The oxygen-injection SnS_(2) nanosheets exhibit a remarkable Faradaic efficiency of 91.6%for carbonaceous products with a current density of 24.1 mA cm^(−2) at−0.9 V vs RHE,including 83.2%for formate production and 16.5%for syngas with the CO/H_(2) ratio of 1:1.By operando X-ray absorption spectroscopy,we unravel the in situ surface oxygen doping into the matrix during reaction,thereby optimizing the Sn local electronic states.Operando synchrotron radiation infrared spectroscopy along with theoretical calculations further reveals that the surface oxygen doping facilitated the CO_(2) activation and enhanced the affinity for HCOO*species.This result demonstrates the potential strategy of surface oxygen injection for the rational design of advanced catalysts for CO_(2) electroreduction.展开更多
Crystal growth of calcium carbonate in biological simulation was investigated via egg white protein with different volume fractions,during which calcium carbonate was synthesized by calcium chloride and sodium carbona...Crystal growth of calcium carbonate in biological simulation was investigated via egg white protein with different volume fractions,during which calcium carbonate was synthesized by calcium chloride and sodium carbonate.The morphology,thermal properties and microstructure of the calcium carbonate micro-to-nanoscale crystals were characterized by scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,Fourier transform infrared spectroscopy（FTIR）,thermogravimetric analysis（TG） and X-ray diffraction（XRD） analysis.The results show that the volume fraction of egg white protein has great influence on the shape,size and morphology of calcium carbonate crystals.The calcium carbonate crystals were the mixtures of calcite-vaterite-like crystals including spherical and rough surface,which are different from that formed in pure water.With the increase of egg white protein concentration,the diameter of calcium carbonate crystals changed,the amount of formed spherical calcium carbonate particles decreased and that of vaterite increased.These results indicate that the coordination and electrostatic interaction between egg white protein and Ca2＋ significantly affect the calcium carbonate crystalization.展开更多
A systematic research on the electron deposition process in the JAEA 10 A ion source is carried out by using a particle-in-cell/Monte Carlo collision simulation, which is based on a full three-dimensional self-develop...A systematic research on the electron deposition process in the JAEA 10 A ion source is carried out by using a particle-in-cell/Monte Carlo collision simulation, which is based on a full three-dimensional self-developed code. Two parts are studied. One is the space and energy distribution of fast and slow electrons, the other is the vibration excitation collisions between electrons and hydrogen moleculars. The results show that the inhomogeneity of electrons comes from the Y direction drift of the fast electrons （Te ≥25 eV） due to the action of the magnetic fields. This drift also increases the number of vibration excitation collisions in the -Y direction, and results in the increase of Ha in the -Y direction, eventually leading to the -Y drift of H^-. It explains the spatial non-uniformity in the JAEA 10 A ion source.展开更多
Systematic calculations of low-lying energy levels,B(E2)transitions,and g factors of even-even tellurium isotopes with mass numbers from 128 to 140 are performed via the nucleon-pair approximation(NPA)of the shell mod...Systematic calculations of low-lying energy levels,B(E2)transitions,and g factors of even-even tellurium isotopes with mass numbers from 128 to 140 are performed via the nucleon-pair approximation(NPA)of the shell model with phenomenological multipole-multipole interactions.An optimal agreement is obtained between the calculated results and experimental data.The yrast band structures of nuclei below and above the N=82 shell closure are compared and discussed.In particular,the evolutionary differences of B(E2;2^(+)_(1)→0^(+)_(1))values and g(2^(+)_(1))factors,with respect to the symmetry of N=82,are attributed to the dominant contribution differences in neutron and proton excitations,respectively.展开更多
Engineering the electronic properties of catalysts to target intermediate adsorption energy as well as harvest high selectivity represents a promising strategy to design advanced electrocatalysts for efficient CO_(2) ...Engineering the electronic properties of catalysts to target intermediate adsorption energy as well as harvest high selectivity represents a promising strategy to design advanced electrocatalysts for efficient CO_(2) electroreduction.Herein,a synergistical tuning on the electronic structure of the Cd Se nanorods is proposed for boosting electrochemical reduction of CO_(2) .The synergy of Ag doping coupled with Se vacancies tuned the electronic structure of the CdSe nanorods,which shows the metalloid characterization and thereby the accelerated electron transfer of CO_(2) electroreduction.Operando synchrotron radiation Fourier transform infrared spectroscopy and theoretical simulation revealed that the Ag doping and Se vacancies accelerated the CO_(2) activation process and lowered the energy barrier for the conversion from CO_(2) to;COOH;as a result,the performance of CO_(2) electroreduction was enhanced.The as-obtained metalloid Ag-doped CdSe nanorods exhibited a 2.7-fold increment in current density and 1.9-fold Faradaic efficiency of CO compared with the pristine CdSe nanorod.展开更多
For MWPCs used for X-ray position detection, simulation studies of the anode wire modulation effect of the detector were carried out using the Garfield program. Different gas mixtures were used as the working gas in t...For MWPCs used for X-ray position detection, simulation studies of the anode wire modulation effect of the detector were carried out using the Garfield program. Different gas mixtures were used as the working gas in the simulation, so as to obtain the influence of the X-ray cross section and electron diffusion coefficient of the working gases on the anode wire modulation effect of an MWPC with anode wire spacing of 2 mm. Results show that, though a working gas with higher X-ray cross section implies a larger average drift distance for the ionized electrons, such gas mixtures are of little use in improving the anode wire modulation effect of MWPCs. It is found that the transverse electron diffusion coefficient is the determining factor for the extent of the anode wire modulation effect in the detector.展开更多
A simulation study of the parallax effect of gaseous detectors using the Garfield program is reported. A method that mainly uses non-uniform cathode potentials to reduce the parallax error of planar type gas detectors...A simulation study of the parallax effect of gaseous detectors using the Garfield program is reported. A method that mainly uses non-uniform cathode potentials to reduce the parallax error of planar type gas detectors is described. By applying it to MWPC and Micro-pattern gas detectors, the method reduces the parallax broadening with very good results. For a 13° incidence track, the width （FWHM） of the parallax broadening is reduced to less than 20% of the normal one after using the special cathode potentials.展开更多
The electric quadrupole moment Q and the magnetic momentp(or the g factor)of low-lying states in even-even nuclei 72-80Ge and odd-mass nuclei 75-79 Ge are studied in the framework of the nucleon pair approximation(NPA...The electric quadrupole moment Q and the magnetic momentp(or the g factor)of low-lying states in even-even nuclei 72-80Ge and odd-mass nuclei 75-79 Ge are studied in the framework of the nucleon pair approximation(NPA)of the shell model,assuming the monopole and quadrupole pairing plus quadrupole-quadrupole interaction.HA H.Our calculations reproduce well the experimental values of Q(21^+)and g(21^+)for 72,74,76 Ge,as well as the yrast energy levels of these isotopes.The structure of the 21^+states and the contributions of the proton and neutron components in Q(21^+)and g(21^+)are discussed in the SD-pair truncated shell-model subspace.The overall trend of Q(21^+)and g(21^+)as a function of the mass number A,as well as their signs,are found to originate essentially from the proton contribution.The negative value of Q(21^+)in 72,74Ge is suggested to be due to the enhanced quadrupole-quadrupole correlation and configuration mixing.展开更多
Exploiting the intelligent photocatalysts capable of phase separation provides a promising solution to the removal of uranium,which is expected to solve the difficulty in separation and the poor selectivity of traditi...Exploiting the intelligent photocatalysts capable of phase separation provides a promising solution to the removal of uranium,which is expected to solve the difficulty in separation and the poor selectivity of traditional photocatalysts in carbonate-containing uranium wastewater.In this paper,theγ-FeOOH/konjac glucomannan grafted with phenolic hydroxyl groups/poly-N-isopropylacrylamide(γ-FeOOH/KGM(Ga)/PNIPAM)thermosensitive hydrogel is proposed as the photocatalysts for extracting uranium from carbonate-containing uranium wastewater.The dynamic phase transformation is demonstrated to confirm the arbitrary transition ofγ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel from a dispersed state with a high specific surface area at low temperatures to a stable aggregated state at high temperatures.Notably,theγ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel achieves a remarkably high rate of 92.3%in the removal of uranium from the wastewater containing carbonates and maintains the efficiency of uranium removal from uranium mine wastewater at over 90%.Relying on electron spin resonance and free radical capture experiment,we reveal the adsorption-reduction-nucleation-crystalliza tion mechanism of uranium onγ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel.Overall,this strategy provides a promising solution to treating uranium-contaminated wastewater,showing a massive potential in water purification.展开更多
Actinide-based catalysts have been regarded as promising candidates for N_(2) fixation owing to their unique 5f orbital with flexible oxidation states.Herein,we report for the first time the dispersion of uranium(U)si...Actinide-based catalysts have been regarded as promising candidates for N_(2) fixation owing to their unique 5f orbital with flexible oxidation states.Herein,we report for the first time the dispersion of uranium(U)single atoms on TiO_(2) nanosheets via oxygen vacancy confinement for N_(2) electroreduction.The single-atom U catalyst exhibited a high NH_(3) yield of 40.57μg h^(-1) mg^(-1),with a reasonably high Faraday efficiency of 25.77%,ranking first among the reported nitrogen-free catalysts.Isotope-labeling operando synchrotron infrared spectroscopy verifies that the key*N_(2)H_(y) intermediate species was derived from the N_(2) gas of the feed.By using operando X-ray absorption spectroscopy,we found enhanced metal-support interaction between U single atoms and TiO_(2) lattice with more U-O_(latt) coordination under working conditions.Theoretical simulations suggest that the evolved 1O_(ads)-U-4O_(latt) moieties act as a critical electronfeedback center,lowering the thermodynamic energy barrier for the N_(2) dissociation and the first hydrogenation step.This work provides the possibility of tailoring the interaction between metal active sites and supports for designing high-performance actinide-based single-atom catalysts.展开更多
Single-atom catalysts(SACs)have shown unexpected catalytic activity due to their unique electronic structure and coordination environment.Nonetheless,the synthesis of an atomically precise low-coordination single-atom...Single-atom catalysts(SACs)have shown unexpected catalytic activity due to their unique electronic structure and coordination environment.Nonetheless,the synthesis of an atomically precise low-coordination single-atom catalyst remains a grand challenge.Herein,we report a coordinately unsaturated Ni-N_(3)single-atom electrocatalyst using a metal-organic framework(MOF)derived N-C support with abundant exposed N for excellent electrochemical CO_(2)reduction.The obtained Ni-N_(3)/NC active site exhibited highly efficient CO_(2)-to-CO conversion with a Faradaic efficiency of 94.6%at the current density of 100 mA/cm^(2).In situ X-ray absorption spectroscopy(XAS)measurement suggested that the Ni atomic center with unsaturated coordination had the lower initial chemical state and higher charge transfer ability.In situ Fourier transform infrared(FT-IR)and theoretical calculation results revealed that the unsaturated catalytically active center could facilitate activation of CO_(2)and thus heighten CO_(2)electroreduction activity.These findings provided insights into the rational design of definitive coordination structure of SACs for boosting activity and selectivity.展开更多
In this paper,we propose an approach to nucleon-pair approximation(NPA)with m-scheme bases,in which the collective nucleon pairs are represented in terms of antisymmetric matrices,and commutations between nucleon pair...In this paper,we propose an approach to nucleon-pair approximation(NPA)with m-scheme bases,in which the collective nucleon pairs are represented in terms of antisymmetric matrices,and commutations between nucleon pairs are given using a matrix multiplication that avoids angular-momentum couplings and recouplings.Therefore the present approach significantly simplifies the NPA computation.Furthermore,it is formulated on the same footing with and without isospin.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11647059 and 11305151)Research Fund for the Doctoral Program of the Southwest University of Science and Technology(No.14zx7102)Education Reform Project of the Southwest University of Science and Technology(No.17xn0102)
文摘In random-interaction ensembles, the electric quadrupole moments(Q) and magnetic moments(μ) of the Iπ = 11/2-isomers of the Cd isotopes predominantly exhibit a linear correlation with the neutron numbers,corresponding to the recently emphasized linear Q and μsystematics in realistic nuclear systems. Although the seniority scheme enhances such predominance(more essentially for μ), the configuration mixing due to quadrupole-like and δ-force-like proton-neutron(pn) interactions is responsible for the linear Q and μ systematics,respectively, in realistic nuclear system, as well as randominteraction ensembles.
基金Project supported by National Natural Science Foundation of China(Grant Nos.11347134 and 11304254)the Doctor Foundation of Southwest University of Science and Technology,China(Grant No.13zx7125)
文摘We calculated the structural, elastic, and electronic properties of alkali metal Na atoms doped type-I silicon-clathrate compound（Na8Si46） under pressure using first-principles methods. The obtained dependencies of bond lengths and bond angles on pressure show heterogeneous behaviors which may bring out a structural transition. By using the elastic stability criteria from the calculated elastic constants, we confirm that the Na8Si46 is elastically unstable under high pressure. Some of the mechanical and thermal quantities include bulk modulus, shear modulus,Young＇s modulus, Debye temperature,sound velocity, melting point, and hardness, which are also derived from the elastic constants. The calculated total and partial electron densities of states of Na8Si46 indicate a weak interaction between the encapsulated Na atoms and the silicon framework. Moreover, the effect of pressure on its electronic structure is also investigated, which suggests that pressure is not a good choice to enhance the thermoelectricity performance of Na8Si46.
基金the National Natural Science Foundation of China under Grant Nos U1832133,11475229 and 91426301
文摘Helium effects on dislocation and cavity formation of Fe-11 wt.% Cr model alloy are investigated. Single-beam(electron) and dual-beam(He^+/e^-) irradiations are performed at 350℃ and 400℃ using an ultra-high voltage electron microscope combined with ion accelerators. In-situ observation shows that the growth rate of dislocation loops is reduced in the helium pre-injected specimen. The mean size of cavities decreased in the helium preinjected specimen. The possible mechanisms are discussed.
基金The National Natural Science Foundation of China(22276153,51974262)funded this work。
文摘To address the hazardous by-product of zinc smelting and resource utilization of jarosite residue,this study applies an electric field-assisted hot acid treatment to completely recycle iron(Fe).This innovative approach aims to enhance the leaching efficiency of Fe from jarosite residue.The introduction of an electric field changes the charge distribution on the surface of the particles to enhance ions and electrons exchange and promotes the collision between particles to strengthen reaction kinetics.Based on the above,the leaching efficiency of Fe in jarosite under sulfuric acid attack has improved observably.The result shows that Fe leaching efficiency reaches 98.83%,which is increased by 28%under the optimal experimental conditions:current density of 30 mA·cm^(-2),H_(2)SO_(4) concentration of 1.5 mol·L^(-1),solid-liquid ratio of 70 g·L^(-1),temperature of 80℃ and time of 12 h.Leaching kinetics calculations show that the apparent activation energy is 16.97 kJ·mol^(-1) and the leaching of jarosite residue is controlled by a mixture of chemical reaction and diffusion,as well as the temperature and concentration of the leaching solution have an influence on leaching.This work provides a feasible idea for the efficient leaching of Fe from jarosite residue.
基金This work was supported by National Natural Science Foundation of China(Grants No.12025505)China Ministry of Science and Technology(2017YFA0208300)+2 种基金Youth Innovation Promotion Association CAS(CX2310007007 and CX2310000091)Open Fund Project of State Key Laboratory of Environmentally Friendly Energy Materials(20kfhg08)We would thank NSRL and SSRF for the synchrotron beam time.The calculations were performed on the supercomputing system in the Supercomputing Center of University of Science and Technology of China.
文摘Surface chemistry modification represents a promising strategy to tailor the adsorption and activation of reaction intermediates for enhancing activity.Herein,we designed a surface oxygen-injection strategy to tune the electronic structure of SnS_(2) nanosheets,which showed effectively enhanced electrocatalytic activity and selectivity of CO_(2) reduction to formate and syngas(CO and H_(2)).The oxygen-injection SnS_(2) nanosheets exhibit a remarkable Faradaic efficiency of 91.6%for carbonaceous products with a current density of 24.1 mA cm^(−2) at−0.9 V vs RHE,including 83.2%for formate production and 16.5%for syngas with the CO/H_(2) ratio of 1:1.By operando X-ray absorption spectroscopy,we unravel the in situ surface oxygen doping into the matrix during reaction,thereby optimizing the Sn local electronic states.Operando synchrotron radiation infrared spectroscopy along with theoretical calculations further reveals that the surface oxygen doping facilitated the CO_(2) activation and enhanced the affinity for HCOO*species.This result demonstrates the potential strategy of surface oxygen injection for the rational design of advanced catalysts for CO_(2) electroreduction.
基金Supported by the Key Projects in the National Science & Technology Pillar Program During the Eleventh Five-year Plan Period,China(No.2007BAB18B08)
文摘Crystal growth of calcium carbonate in biological simulation was investigated via egg white protein with different volume fractions,during which calcium carbonate was synthesized by calcium chloride and sodium carbonate.The morphology,thermal properties and microstructure of the calcium carbonate micro-to-nanoscale crystals were characterized by scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,Fourier transform infrared spectroscopy（FTIR）,thermogravimetric analysis（TG） and X-ray diffraction（XRD） analysis.The results show that the volume fraction of egg white protein has great influence on the shape,size and morphology of calcium carbonate crystals.The calcium carbonate crystals were the mixtures of calcite-vaterite-like crystals including spherical and rough surface,which are different from that formed in pure water.With the increase of egg white protein concentration,the diameter of calcium carbonate crystals changed,the amount of formed spherical calcium carbonate particles decreased and that of vaterite increased.These results indicate that the coordination and electrostatic interaction between egg white protein and Ca2＋ significantly affect the calcium carbonate crystalization.
基金supported by the National Natural Science Foundation of China(Grant No.11176032)the China Academy of Engineering Physics(CAEP)THz Science and Technology Foundation(Grant No.CAEPTHZ201209)+1 种基金the Scientific Reserch Fund of Sichuan Provincial Education Department,China(GrantNo.12ZA183)the Southwest University of Science and Technology Doctor Fund,China(Grant No.13zx7106)
文摘A systematic research on the electron deposition process in the JAEA 10 A ion source is carried out by using a particle-in-cell/Monte Carlo collision simulation, which is based on a full three-dimensional self-developed code. Two parts are studied. One is the space and energy distribution of fast and slow electrons, the other is the vibration excitation collisions between electrons and hydrogen moleculars. The results show that the inhomogeneity of electrons comes from the Y direction drift of the fast electrons （Te ≥25 eV） due to the action of the magnetic fields. This drift also increases the number of vibration excitation collisions in the -Y direction, and results in the increase of Ha in the -Y direction, eventually leading to the -Y drift of H^-. It explains the spatial non-uniformity in the JAEA 10 A ion source.
基金Supported by National Natural Science Foundation of China (11875188, 11905130 and 12075169)Sichuan Science and Technology Program (2019JDRC0017)+1 种基金the Doctoral Program of Southwest University of Science and Technology (18zx7147)Shanghai Sailing Program (19YF1434200)。
文摘Systematic calculations of low-lying energy levels,B(E2)transitions,and g factors of even-even tellurium isotopes with mass numbers from 128 to 140 are performed via the nucleon-pair approximation(NPA)of the shell model with phenomenological multipole-multipole interactions.An optimal agreement is obtained between the calculated results and experimental data.The yrast band structures of nuclei below and above the N=82 shell closure are compared and discussed.In particular,the evolutionary differences of B(E2;2^(+)_(1)→0^(+)_(1))values and g(2^(+)_(1))factors,with respect to the symmetry of N=82,are attributed to the dominant contribution differences in neutron and proton excitations,respectively.
基金supported by the National Natural Science Foundation of China(12025505 and 21873050)China Ministry of Science and Technology(2017YFA0208300)+1 种基金the Open Fund Project of State Key Laboratory of Environmentally Friendly Energy Materials(20KFHG08)the Youth Innovation Promotion Association CAS(CX2310007007 and CX2310000091)。
文摘Engineering the electronic properties of catalysts to target intermediate adsorption energy as well as harvest high selectivity represents a promising strategy to design advanced electrocatalysts for efficient CO_(2) electroreduction.Herein,a synergistical tuning on the electronic structure of the Cd Se nanorods is proposed for boosting electrochemical reduction of CO_(2) .The synergy of Ag doping coupled with Se vacancies tuned the electronic structure of the CdSe nanorods,which shows the metalloid characterization and thereby the accelerated electron transfer of CO_(2) electroreduction.Operando synchrotron radiation Fourier transform infrared spectroscopy and theoretical simulation revealed that the Ag doping and Se vacancies accelerated the CO_(2) activation process and lowered the energy barrier for the conversion from CO_(2) to;COOH;as a result,the performance of CO_(2) electroreduction was enhanced.The as-obtained metalloid Ag-doped CdSe nanorods exhibited a 2.7-fold increment in current density and 1.9-fold Faradaic efficiency of CO compared with the pristine CdSe nanorod.
基金Supported by Scientific Research Fund of Sichuan Provincial Education Department(11ZA140)
文摘For MWPCs used for X-ray position detection, simulation studies of the anode wire modulation effect of the detector were carried out using the Garfield program. Different gas mixtures were used as the working gas in the simulation, so as to obtain the influence of the X-ray cross section and electron diffusion coefficient of the working gases on the anode wire modulation effect of an MWPC with anode wire spacing of 2 mm. Results show that, though a working gas with higher X-ray cross section implies a larger average drift distance for the ionized electrons, such gas mixtures are of little use in improving the anode wire modulation effect of MWPCs. It is found that the transverse electron diffusion coefficient is the determining factor for the extent of the anode wire modulation effect in the detector.
基金Supported by Scientific Research Fund of the Sichuan Provincial Education Department(11ZA140)Scientific Research Fund of Southwest University of Science and Technology(10zx7123)
文摘A simulation study of the parallax effect of gaseous detectors using the Garfield program is reported. A method that mainly uses non-uniform cathode potentials to reduce the parallax error of planar type gas detectors is described. By applying it to MWPC and Micro-pattern gas detectors, the method reduces the parallax broadening with very good results. For a 13° incidence track, the width （FWHM） of the parallax broadening is reduced to less than 20% of the normal one after using the special cathode potentials.
基金Supported by National Natural Science Foundation of China(11875188)Open Project Fund of Shanghai Key Laboratory of Particle Physics and Cosmology(18DZ2271500-2)+1 种基金Sichuan Science and Technology Program(2019JDRC0017)the Doctoral Program of Southwest University of Science and Technology(18zx7147)
文摘The electric quadrupole moment Q and the magnetic momentp(or the g factor)of low-lying states in even-even nuclei 72-80Ge and odd-mass nuclei 75-79 Ge are studied in the framework of the nucleon pair approximation(NPA)of the shell model,assuming the monopole and quadrupole pairing plus quadrupole-quadrupole interaction.HA H.Our calculations reproduce well the experimental values of Q(21^+)and g(21^+)for 72,74,76 Ge,as well as the yrast energy levels of these isotopes.The structure of the 21^+states and the contributions of the proton and neutron components in Q(21^+)and g(21^+)are discussed in the SD-pair truncated shell-model subspace.The overall trend of Q(21^+)and g(21^+)as a function of the mass number A,as well as their signs,are found to originate essentially from the proton contribution.The negative value of Q(21^+)in 72,74Ge is suggested to be due to the enhanced quadrupole-quadrupole correlation and configuration mixing.
基金supported by the National Natural Science Foundation of China(21976147,U2267224,and 22106126)the Sichuan Science and Technology Program(2021YFG0096,2024NSFSC1148,2022YFG0371,and 2024NSFTD0012)+2 种基金the Project of State Key Laboratory of Environmentfriendly Energy Materials in Southwest University of Science and Technology(21fksy22)the Research Fund of Southwest University of Science and Technology for PhD(23zx7103)the Open Fund of China National Nuclear Corporation Key Laboratory for Uranium Extraction from Seawater(KLUES202201).
文摘Exploiting the intelligent photocatalysts capable of phase separation provides a promising solution to the removal of uranium,which is expected to solve the difficulty in separation and the poor selectivity of traditional photocatalysts in carbonate-containing uranium wastewater.In this paper,theγ-FeOOH/konjac glucomannan grafted with phenolic hydroxyl groups/poly-N-isopropylacrylamide(γ-FeOOH/KGM(Ga)/PNIPAM)thermosensitive hydrogel is proposed as the photocatalysts for extracting uranium from carbonate-containing uranium wastewater.The dynamic phase transformation is demonstrated to confirm the arbitrary transition ofγ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel from a dispersed state with a high specific surface area at low temperatures to a stable aggregated state at high temperatures.Notably,theγ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel achieves a remarkably high rate of 92.3%in the removal of uranium from the wastewater containing carbonates and maintains the efficiency of uranium removal from uranium mine wastewater at over 90%.Relying on electron spin resonance and free radical capture experiment,we reveal the adsorption-reduction-nucleation-crystalliza tion mechanism of uranium onγ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel.Overall,this strategy provides a promising solution to treating uranium-contaminated wastewater,showing a massive potential in water purification.
基金supported by the National Key R&D Program of China(2021YFA1600800)the National Natural Science Foundation of China(12025505,21976147,and 22106126)+3 种基金the University of China Innovation Program of Anhui Province(GXXT-2020-053)the Youth Innovation Promotion Association CAS(2015366)Open Fund Project of State Key Laboratory of Environmentally Friendly Energy Materials(20kfhg08)Collaborative Innovation Program of Hefei Science Center(2021HSC-CIP006)。
文摘Actinide-based catalysts have been regarded as promising candidates for N_(2) fixation owing to their unique 5f orbital with flexible oxidation states.Herein,we report for the first time the dispersion of uranium(U)single atoms on TiO_(2) nanosheets via oxygen vacancy confinement for N_(2) electroreduction.The single-atom U catalyst exhibited a high NH_(3) yield of 40.57μg h^(-1) mg^(-1),with a reasonably high Faraday efficiency of 25.77%,ranking first among the reported nitrogen-free catalysts.Isotope-labeling operando synchrotron infrared spectroscopy verifies that the key*N_(2)H_(y) intermediate species was derived from the N_(2) gas of the feed.By using operando X-ray absorption spectroscopy,we found enhanced metal-support interaction between U single atoms and TiO_(2) lattice with more U-O_(latt) coordination under working conditions.Theoretical simulations suggest that the evolved 1O_(ads)-U-4O_(latt) moieties act as a critical electronfeedback center,lowering the thermodynamic energy barrier for the N_(2) dissociation and the first hydrogenation step.This work provides the possibility of tailoring the interaction between metal active sites and supports for designing high-performance actinide-based single-atom catalysts.
基金supported by Guangdong Basic and Applied Basic Research Foundation(No.2022A1515011828)Natural Science Foundation of Guangdong Province(No.2022A1515012661)+4 种基金the National Key R&D Program of China(Nos.2021YFA1600800 and 2020YFA0710203)the National Natural Science Foundation of China(Nos.12025505,22179125,22002147,22106126,and 12205304)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0450200)the Youth Innovation Promotion Association CAS(Nos.2015366 and 2022458)the Collaborative Innovation Program of Hefei Science Center,CAS(No.2021HSC-CIP006).
文摘Single-atom catalysts(SACs)have shown unexpected catalytic activity due to their unique electronic structure and coordination environment.Nonetheless,the synthesis of an atomically precise low-coordination single-atom catalyst remains a grand challenge.Herein,we report a coordinately unsaturated Ni-N_(3)single-atom electrocatalyst using a metal-organic framework(MOF)derived N-C support with abundant exposed N for excellent electrochemical CO_(2)reduction.The obtained Ni-N_(3)/NC active site exhibited highly efficient CO_(2)-to-CO conversion with a Faradaic efficiency of 94.6%at the current density of 100 mA/cm^(2).In situ X-ray absorption spectroscopy(XAS)measurement suggested that the Ni atomic center with unsaturated coordination had the lower initial chemical state and higher charge transfer ability.In situ Fourier transform infrared(FT-IR)and theoretical calculation results revealed that the unsaturated catalytically active center could facilitate activation of CO_(2)and thus heighten CO_(2)electroreduction activity.These findings provided insights into the rational design of definitive coordination structure of SACs for boosting activity and selectivity.
基金the Sichuan Science and Technology Program(2019JDRC0017)Doctoral Program of Southwest University of Science and Technology(18zx7147)+4 种基金National Natural Science Foundation of China(11705100)Youth Innovations and Talents Project of Shandong Provincial Colleges,and Universities(201909118)Higher Educational Youth Innovation Science and Technology Program Shandong Province(2020KJJ004)National Natural Science Foundation of China(11975151,11675101,11961141003)MOE Key Lab for Particle Physics,Astrophysics and Cosmology for financial support。
文摘In this paper,we propose an approach to nucleon-pair approximation(NPA)with m-scheme bases,in which the collective nucleon pairs are represented in terms of antisymmetric matrices,and commutations between nucleon pairs are given using a matrix multiplication that avoids angular-momentum couplings and recouplings.Therefore the present approach significantly simplifies the NPA computation.Furthermore,it is formulated on the same footing with and without isospin.
