With the rapid development of machine learning,the prediction of the performance of acoustic meta-materials using neural networks is replacing the traditional experiment-based testing methods.In this paper,a Gini impu...With the rapid development of machine learning,the prediction of the performance of acoustic meta-materials using neural networks is replacing the traditional experiment-based testing methods.In this paper,a Gini impurity-based artificial neural network structural optimizer(GIASO)is proposed to optimize the neural network structure,and the effects of five different initialization algorithms on the model performance and struc-ture optimization are investigated.Two physically guided models with additional resonant frequencies and sound transmission loss formula are achieved to further improve the prediction accuracy of the model.The results show that GIASO utilizing the gray wolf optimizer as the initialization method can significantly improve the prediction performance of the model.Simultaneously,the physical guidance model with additional resonant frequencies has the best performance and can better predict the edge data points.Eventually,the effect of each input parameter on the sound transmission loss is explained by combining sensitivity analysis and theoretical formulation.展开更多
Clothianidin(CLO)is an insecticide with a high prevalence in environment and food samples.The identification of structural impurities is of great importance for the development of certified reference materials.Here,a ...Clothianidin(CLO)is an insecticide with a high prevalence in environment and food samples.The identification of structural impurities is of great importance for the development of certified reference materials.Here,a heuristic method for CLO impurity analysis combining liquid chromatography-high resolution mass spectrometry(Orbitrap)and a molecular annotation platform(SIRIUS)was applied.Precursor and product ion mass data was used to predict candidate chemical formulas,and SIRIUS,isotopes,fragmentation trees and ZODIAC scores were calculated for ranking.The chemical structures of the impurities were inferred based on the characteristic fragments of the main component CLO.Finally,25 impurities were identified and classified into four groups based on their structural differences.Among them,3 impurities had CAS registration numbers and 1 impurity was validated with a standard by HPLC-UV and mass spectrum.This work successfully combines ab initio identification tools with intellect in the analysis of structural related impurities.展开更多
In past decades,ABX_(3) halide perovskites have attracted great interest in solar cells due to excellent opto-electronic properties,such as high carrier mobility.However,instability and toxicity are obstacles on the c...In past decades,ABX_(3) halide perovskites have attracted great interest in solar cells due to excellent opto-electronic properties,such as high carrier mobility.However,instability and toxicity are obstacles on the commercial route for perovskites.Many studies have turned to exploring A_(2) BX_(6) and A_(3) B_(2) X_(9) for better stability.Unfortunately,the carrier mobilities of these two types are inferior to ABX_(3),lower by an order of magnitude.Furthermore,the mobility of ABX_(3) is distributed over a large range of 1.78-4500 cm^(2) V^(−1) s^(−1) in experiments,which contributes to another diversity of mobilities.In this paper,we aim at reveal-ing the physical origin of the above-mentioned diversities by theoretical studies on CsBX_(3),Cs_(2) BX_(6),and Cs_(3) B_(2) X_(9)(B=Sn,Pb,Sb,Bi,X=Br,Cl).The difference in group velocities is the major reason responsible for the variation in these types.The unique three-dimensional connected conductive network of CsBX_(3) determines its large group velocity.As for carrier scattering,ionized impurity scattering dominates at low carrier and high ionized impurity concentrations.Detailed analysis reveals that band degeneracy is strongly related to the impurity scattering rate,while dielectric constant is almost immune.Our study provides a better understanding of the relationship between electronic structures and mobilities for po-tential applications in photovoltaics.展开更多
During the EAST radiative divertor experiments,one of the key challenges was how to avoid the occurrence of disruptive events caused by excessive impurity seeding.To estimate the required impurity fraction for diverto...During the EAST radiative divertor experiments,one of the key challenges was how to avoid the occurrence of disruptive events caused by excessive impurity seeding.To estimate the required impurity fraction for divertor detachment,we introduce a reduced edge plasma radiation model.In the model,based on the momentum conservation along the magnetic field line,the upstream pressure is determined by the plasma density and temperature at the divertor target,and then the impurity radiation loss is obtained by the balance of the heat and particle fluxes.It is found that the required impurity fraction shows a non-monotonic variation with divertor electron temperature(T_(d))when 0.1 eV<T_(d)<10 eV.In the range of 0.1 eV<T_(d)<1 e V,the position near the valley of required impurity fraction corresponds to strong plasma recombination.Due to the dependence of the volumetric momentum loss effect on the T_(d)in the range of 1 eV<T_(d)<10 eV,the required impurity fraction peaks and then decreases as T_(d)is increased.Compared to neon,the usage of argon reduces the impurity fraction by about twice.In addition,for the various fitting parameters in the pressure-momentum loss model,it is shown that the tendency of required impurity fraction with T_(d)always increases first and then decreases in the range of 1 eV<T_(d)<10 eV,but the required impurity fraction decreases when the model that characterizes the strong loss in pressure momentum is used.展开更多
High purity magnesium is not only an important basic raw material for semiconductor and electronics industries,but also a promising new generation of electrochemical energy storage materials and biomedical materials.I...High purity magnesium is not only an important basic raw material for semiconductor and electronics industries,but also a promising new generation of electrochemical energy storage materials and biomedical materials.Impurities in high-purity magnesium affect material properties,which has become the most critical factor restricting its application.However,accurate analysis of multiple ultra-trace impurity elements in high-purity magnesium is extremely challenging.In this paper,based on the synergistic effect of N_(2)O/H_(2) reaction gas mixture to eliminate spectral interference of inductively coupled plasma tandem mass spectrometry(ICP-MS/MS),a new strategy for the quantification of 45 ultra-trace impurity elements in high-purity magnesium was proposed.The results indicated that the limits of detection(LOD)were in the range of 0.02–18.5 ng L^(−1);the LODs of the challenging non-metallic elements Si and S were 18.5 and 12.2 ng L^(−1),respectively;and the LODs of all the other analytes were less than 10 ng L^(−1).Even under hot plasma conditions,LODs of alkali metal elements were also less than 5 ng L^(−1).The spike recovery of each analyte was 93.6%–107%,and the relative standard deviation(RSD)was 3.2%–6.9%,respectively.At a 95%level of confidence,no significant differences were found between the results obtained under the optimal conditions for the analyte with the developed method and the measurement results of SF-ICP-MS.The developed method indicated low LOD,high sample throughput,and complete interference elimination,demonstrating a new avenue for the rapid determination of ultra-trace elements in high-purity magnesium.展开更多
Tearing modes may play an important role in the density limit disruption.The Magnetohydrodynamic(MHD)code CLT with impurity modules is used to study the tearing mode excited and driven by impurity radiation.The impuri...Tearing modes may play an important role in the density limit disruption.The Magnetohydrodynamic(MHD)code CLT with impurity modules is used to study the tearing mode excited and driven by impurity radiation.The impurity radiation can lead to plasma contraction and local enhancement of the current density.When the locally enhanced region of the current density approaches to the resonance surface,the tearing mode can be excited,even if the tearing mode is stable in the initial equilibrium.Through a scan of the initial atomic number(Z)and impurity concentrations,it is found that impurities with different Z values exhibit similar behaviors in the radiation-driven tearing mode.The impurity radiation can drive tearing mode growth through temperature cooling near the resonance surface,and there exists a linear relationship between the temperature perturbation caused by impurity radiation and the linear growth rate of the tearing mode.Additionally,the impurity can promote the growth of magnetic islands through the radiation cooling inside the magnetic island,and there exists a correlation between the initial parameters of impurity and the width of the saturated magnetic island.展开更多
Ion-absorbed rare-earth ore is an important mineral resource which is widely extracted by in-situ leaching process. And such process generates a significant amount of impurities such as aluminum and iron ions in leach...Ion-absorbed rare-earth ore is an important mineral resource which is widely extracted by in-situ leaching process. And such process generates a significant amount of impurities such as aluminum and iron ions in leaching solution simultaneously. The surface characteristics and interactions by infrared spectroscopy and X-ray diffraction were studied to optimize the leaching conditions. It is found that the environment-friendly depressant LG-01 can react with the impurity ions through the formation of a new complex on the surface of leaching residues. Thus, it reduces significantly the concentration of impurity ions in leaching solution and improves the leaching rate of rare-earth ore. Moreover, a leaching rate of 95.6% and an impurity removal rate of 92% have been achieved under the optimized conditions.展开更多
Six kinds of galena with different impurities were synthesized and the effects of impurities on the floatability of galena were investigated. The thermodynamic and kinetic parameters on the galena surface were measure...Six kinds of galena with different impurities were synthesized and the effects of impurities on the floatability of galena were investigated. The thermodynamic and kinetic parameters on the galena surface were measured using microcalorimetry, and the adsorption configuration and energy of butyl xanthate on the surfaces of galena with different impurities were simulated by density functional theory. Flotation experiments showed that Ag and Bi significantly promoted the recovery of galena, while Zn, Sb, Mn, and Cu reduced the recovery of the flotation. Microthermokinetic results indicated that the absolute value of xanthate adsorption heat was directly proportional to the flotation recovery of galena. Adsorption heat and reaction rate coefficients of xanthate on galena containing Ag or Bi were larger than those on pure galena, but smaller on galena containing Cu or Sb. Additionally, the relationship between the heat of unsaturated adsorption of xanthate and the adsorption energy of impurity atom on galena surface was investigated.展开更多
The electronic property of pyrite supercell containing As,Se,Te,Co or Ni hetero atoms were calculated using density functional theory（DFT）,and the reactivities of pyrite with oxygen and xanthate were discussed by fr...The electronic property of pyrite supercell containing As,Se,Te,Co or Ni hetero atoms were calculated using density functional theory（DFT）,and the reactivities of pyrite with oxygen and xanthate were discussed by frontier orbital methods.The cell volume expands due to the presence of impurity.Co and Ni mainly affect the bands near Fermi levels,while As mainly affects the shallow and deep valence bands,and Se and Te mainly affect the deep valence bands.Electronic density analysis suggests that there exists a strong covalent interaction between hetero atom and its surrounding atoms.By frontier orbital calculation,it is suggested that As,Co and Ni have greater influence on the HOMO and LUMO of pyrite than Se and Te.In addition,pyrite containing As,Co or Ni is easier to oxidize by oxygen than pyrite containing Se or Te,and pyrite containing Co or Ni has greater interaction with collector.These are in agreement with the observed pyrite practice.展开更多
Effect of sulfur impurity on coke reactivity was investigated by simulating petroleum coke with low-impurity pitch coke and impurities doping. And its mechanism was discussed by X-ray diffraction (XRD), scanning elect...Effect of sulfur impurity on coke reactivity was investigated by simulating petroleum coke with low-impurity pitch coke and impurities doping. And its mechanism was discussed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The results show that sulfur has strong catalysis on both air and CO2 reactivity of coke in the case of no other impurity interference. Its catalysis is probably realized by triggering organic sulfur→H2S→SO2→COS and elemental sulfur (Sx)→SO2 and organic sulfur→H2S→COS→Sx→C2S→COS reaction systems during coke?O2 and coke?CO2 reactions, respectively, which are partly circular with functions of increasing carbon consumption and enlarging coke specific surface area.展开更多
We report herein the synthesis of impurity B of Flumazenil via demethylation, benzyl protection, cyclization and debenzylation from 7-methoxyl-3,4-dihydro-4-methyl-2H-1,4-benzo-diazepine-2,5（1H）-dione. The structure...We report herein the synthesis of impurity B of Flumazenil via demethylation, benzyl protection, cyclization and debenzylation from 7-methoxyl-3,4-dihydro-4-methyl-2H-1,4-benzo-diazepine-2,5（1H）-dione. The structure of impurity B of Flurnazenil was confirmed by 1n N/V[R, 13C NMR and HRMS, and the overall yield was 29.3%. The finding will be helpful for optimizing the synthetic process and quality control of Flumazenil.展开更多
Modifying effect and mechanism of trace rare earth on Fe(Si) rich impurity phases in commercial purity aluminum were studied with the aids of SEM, EDAX, TEM, etc. It is found that Ce rich mixed rare earth (RE) is an...Modifying effect and mechanism of trace rare earth on Fe(Si) rich impurity phases in commercial purity aluminum were studied with the aids of SEM, EDAX, TEM, etc. It is found that Ce rich mixed rare earth (RE) is an effective modifying agent, which makes the coarse Fe rich impurity phases transform into complex compounds of tiny, sphere/short stick form, thus improving mechanical properties of this material; its modifying mechanism is in that RE gathering in front of solid/liquid interface enters into the impurity phases, forming complex (AlFeSiRE) compounds; or is adsorbed in the impurity phases surface, impeding the growth of impurity phases; however, excessive RE will result in the increasing of RE compounds (secondary phases), and plasticity reduction of this material. Therefore, its addition amount should be less than 0 07% (mass fraction).展开更多
We consider a three-electron system in the Impurity Hubbard model with a coupling between nearest-neighbors. Our research aim consists of studying the structure of essential spectrum and discrete spectra of the energy...We consider a three-electron system in the Impurity Hubbard model with a coupling between nearest-neighbors. Our research aim consists of studying the structure of essential spectrum and discrete spectra of the energy operator of three-electron systems in the impurity Hubbard model in the quartet state of the system in a <em>v</em>-dimensional lattice. We have reduced the study of the spectrum of the three-electron quartet state operator in the impurity Hubbard model to the study of the spectrum of a simpler operator. We proved the essential spectra of the three-electron systems in the Impurity Hubbard model in the quartet state is the union of no more than six segments, and the discrete spectrum of the system is consists of no more than four eigenvalues.展开更多
In the Large Helical Device(LHD),diborane(B2H6)is used as a standard boron source for boronization,which is assisted by helium glow discharges.In 2019,a new Impurity Powder Dropper(IPD)system was installed and is unde...In the Large Helical Device(LHD),diborane(B2H6)is used as a standard boron source for boronization,which is assisted by helium glow discharges.In 2019,a new Impurity Powder Dropper(IPD)system was installed and is under evaluation as a real-time wall conditioning technique.In the LHD,which is a large-sized heliotron device,an additional helium(He)glow discharge cleaning(GDC)after boronization was operated for a reduction in hydrogen recycling from the coated boron layers.This operational time of 3 h was determined by spectroscopic data during glow discharges.A flat hydrogen profile is obtained on the top surface of the coated boron on the specimen exposed to boronization.The results suggest a reduction in hydrogen at the top surface by He-GDC.Trapped oxygen in coated boron was obtained by boronization,and the coated boron,which has boron-oxide,on the first wall by B-IPD was also shown.Considering the difference in coating areas between B2H6 boronization and B-IPD operation,it would be most effective to use the IPD and B2H6 boronization coating together for optimized wall conditioning.展开更多
Plasma radiation characteristics in EAST argon（Ar） gas and neon（Ne） gas seeding experiments are studied.The radiation profiles reconstructed from the fast bolometer measurement data by tomography method are compar...Plasma radiation characteristics in EAST argon（Ar） gas and neon（Ne） gas seeding experiments are studied.The radiation profiles reconstructed from the fast bolometer measurement data by tomography method are compared with the ones got from the simulation program based on corona model.And the simulation results coincide roughly with the experimental data.For Ar seeding discharges,the substantial enhanced radiations can be generally observed in the edge areas at normalized radius ρ_（pol）~0.7–0.9,while the enhanced regions are more outer for Ne seeding discharges.The influence of seeded Ar gas on the core radiation is related to the injected position.In discharges with LSN divertor configuration,the Ar ions can permeate into the core region more easily when being injected from the opposite upper divertor ports.In USN divertor configuration,the W impurity sputtered from the upper divertor target plates are observed to be an important contributor to the increase of the core radiation no matter impurity seeding from any ports.The maximum radiated power fractions f_（rad）（P_（rad）/P_（heat）） about 60%–70% have been achieved in the recent EAST experimental campaign in 2015–2016.展开更多
The effect of impurity element Fe on corrosion behavior of AZ61 magnesium alloys in various states has been investigated by immersion test and hydrogen evolution measurements in 3.5% sodium chloride solution.The corro...The effect of impurity element Fe on corrosion behavior of AZ61 magnesium alloys in various states has been investigated by immersion test and hydrogen evolution measurements in 3.5% sodium chloride solution.The corrosion rate is found to relay on the impurity Fe concentration in the alloys and decreases with decreasing Fe content.When Fe content drops from 150 ppm to 10 ppm,the corresponding corrosion rates under as-cast and solution treatment conditions are reduced from 8.54 mm/a and 8.61 mm/a to 2.54 mm/a and 0.21 mm/a,respectively.The corrosion pattern of the AZ61 alloys is the localized corrosion,and the galvanic couples are formed among the impurity particles,second-phase particles and the matrix.The Fe impurity particles tend to act as main cathodic to form micro-galvanic cell with the α-Mg matrix,which is harmful for corrosion resistance of AZ61 alloy.展开更多
In order to determine the optimal mode of capillary electrophoresis for the impurity control of β-lactam antibiotics, different modes and various electrophoresis conditions for the separation of impurities were compa...In order to determine the optimal mode of capillary electrophoresis for the impurity control of β-lactam antibiotics, different modes and various electrophoresis conditions for the separation of impurities were compared.The results showed that micellar electrokinetic capillary chromatography（MEKC） was the optimal separation mode for the impurity profiling of β-lactam antibiotics.In MEKC,not only the common R and S isomers,Δ-2 andΔ-3 isomers,and Z and E isomers,but also the impurities of β-lactam antibiotics could be well separated compared with the capillary zone electrophoresis.Therefore,MECK is the first choice for the separation of impurities of β-lactam antibiotics with capillary electrophoresis（CE）.The optimal separation could be achieved in MEKC by optimizing the pH and the concentrations of buffered saline,micelles and organic solvent（methanol） in running buffer.展开更多
The distribution rules of impurities in distilled terbium metal were investigated by vacuum distillation purificationexperiment and theoretical analysis.It is found that Ti impurity in distilled terbium is220mg/kg in ...The distribution rules of impurities in distilled terbium metal were investigated by vacuum distillation purificationexperiment and theoretical analysis.It is found that Ti impurity in distilled terbium is220mg/kg in the initial stage of the distillationpurification,increases slowly in the middle stage,and increases rapidly in the last stage,reaching2260mg/kg,and the modifiedseparation coefficient of Ti is1/19.02.The diffusion of the impurity Ti in liquid metal can reach a quasi-equilibrium state in theinitial stage of distillation purification and the calculated results agree well with experimental results;the distribution profile ofimpurity Cu is opposite to Ti,being380mg/kg in the initial stage,decreasing linearly to290mg/kg in the last stage,and themodified separation coefficient is17.99,and the theoretical calculated results are inconsistent with the experimental result.展开更多
Grain boundaries(GBs)have critical influences on the stability and properties of various materials.In this study,first-principles calculations were performed to determine the effects of four metallic impurities(Ni,Al,...Grain boundaries(GBs)have critical influences on the stability and properties of various materials.In this study,first-principles calculations were performed to determine the effects of four metallic impurities(Ni,Al,Bi,and Pb)and three nonmetallic impurities(H,O,and N)on the GBs of silicon carbide(SiC),using the ∑5(210)GBs as models.The GB energy and segregation energy(SE)were calculated to identify the effects of impurities on the GB stability.Electronic interactions considerably influenced the bonding effects of SiC.The formation of weak bonds resulted in the corrosion and embrittlement of GBs.The co-segregation of Bi,Pb,and O was also investigated in detail.展开更多
基金the Science and Technology Commission of Shanghai Municipality(No.19030501100)the Technical Service Platform for Vibration and Noise Testing and Control of New Energy Vehicles(No.18DZ2295900)。
文摘With the rapid development of machine learning,the prediction of the performance of acoustic meta-materials using neural networks is replacing the traditional experiment-based testing methods.In this paper,a Gini impurity-based artificial neural network structural optimizer(GIASO)is proposed to optimize the neural network structure,and the effects of five different initialization algorithms on the model performance and struc-ture optimization are investigated.Two physically guided models with additional resonant frequencies and sound transmission loss formula are achieved to further improve the prediction accuracy of the model.The results show that GIASO utilizing the gray wolf optimizer as the initialization method can significantly improve the prediction performance of the model.Simultaneously,the physical guidance model with additional resonant frequencies has the best performance and can better predict the edge data points.Eventually,the effect of each input parameter on the sound transmission loss is explained by combining sensitivity analysis and theoretical formulation.
基金the National Institute of Metrology(ANL2504)the State Administration for Market Regulation(QNBJ202306).
文摘Clothianidin(CLO)is an insecticide with a high prevalence in environment and food samples.The identification of structural impurities is of great importance for the development of certified reference materials.Here,a heuristic method for CLO impurity analysis combining liquid chromatography-high resolution mass spectrometry(Orbitrap)and a molecular annotation platform(SIRIUS)was applied.Precursor and product ion mass data was used to predict candidate chemical formulas,and SIRIUS,isotopes,fragmentation trees and ZODIAC scores were calculated for ranking.The chemical structures of the impurities were inferred based on the characteristic fragments of the main component CLO.Finally,25 impurities were identified and classified into four groups based on their structural differences.Among them,3 impurities had CAS registration numbers and 1 impurity was validated with a standard by HPLC-UV and mass spectrum.This work successfully combines ab initio identification tools with intellect in the analysis of structural related impurities.
基金supported by the National Key Research and Development Program of China(No.2021YFB3502200)the National Natural Science Foundation of China(Nos.52172216 and 92163212)+1 种基金support from the Shanghai Engi-neering Research Center for Integrated Circuits and Advanced Dis-play Materialssupported by Shanghai Techni-cal Service Center of Science and Engineering Computing,Shanghai University and Hefei Advanced Computing Center.
文摘In past decades,ABX_(3) halide perovskites have attracted great interest in solar cells due to excellent opto-electronic properties,such as high carrier mobility.However,instability and toxicity are obstacles on the commercial route for perovskites.Many studies have turned to exploring A_(2) BX_(6) and A_(3) B_(2) X_(9) for better stability.Unfortunately,the carrier mobilities of these two types are inferior to ABX_(3),lower by an order of magnitude.Furthermore,the mobility of ABX_(3) is distributed over a large range of 1.78-4500 cm^(2) V^(−1) s^(−1) in experiments,which contributes to another diversity of mobilities.In this paper,we aim at reveal-ing the physical origin of the above-mentioned diversities by theoretical studies on CsBX_(3),Cs_(2) BX_(6),and Cs_(3) B_(2) X_(9)(B=Sn,Pb,Sb,Bi,X=Br,Cl).The difference in group velocities is the major reason responsible for the variation in these types.The unique three-dimensional connected conductive network of CsBX_(3) determines its large group velocity.As for carrier scattering,ionized impurity scattering dominates at low carrier and high ionized impurity concentrations.Detailed analysis reveals that band degeneracy is strongly related to the impurity scattering rate,while dielectric constant is almost immune.Our study provides a better understanding of the relationship between electronic structures and mobilities for po-tential applications in photovoltaics.
基金supported by National Natural Science Foundation of China(No.12375227)Innovation in Fusion Engineering Technology of Institute(No.E35QT1080C)。
文摘During the EAST radiative divertor experiments,one of the key challenges was how to avoid the occurrence of disruptive events caused by excessive impurity seeding.To estimate the required impurity fraction for divertor detachment,we introduce a reduced edge plasma radiation model.In the model,based on the momentum conservation along the magnetic field line,the upstream pressure is determined by the plasma density and temperature at the divertor target,and then the impurity radiation loss is obtained by the balance of the heat and particle fluxes.It is found that the required impurity fraction shows a non-monotonic variation with divertor electron temperature(T_(d))when 0.1 eV<T_(d)<10 eV.In the range of 0.1 eV<T_(d)<1 e V,the position near the valley of required impurity fraction corresponds to strong plasma recombination.Due to the dependence of the volumetric momentum loss effect on the T_(d)in the range of 1 eV<T_(d)<10 eV,the required impurity fraction peaks and then decreases as T_(d)is increased.Compared to neon,the usage of argon reduces the impurity fraction by about twice.In addition,for the various fitting parameters in the pressure-momentum loss model,it is shown that the tendency of required impurity fraction with T_(d)always increases first and then decreases in the range of 1 eV<T_(d)<10 eV,but the required impurity fraction decreases when the model that characterizes the strong loss in pressure momentum is used.
基金supported by the Natural Science Foundation of China(52171103 and 21975289).
文摘High purity magnesium is not only an important basic raw material for semiconductor and electronics industries,but also a promising new generation of electrochemical energy storage materials and biomedical materials.Impurities in high-purity magnesium affect material properties,which has become the most critical factor restricting its application.However,accurate analysis of multiple ultra-trace impurity elements in high-purity magnesium is extremely challenging.In this paper,based on the synergistic effect of N_(2)O/H_(2) reaction gas mixture to eliminate spectral interference of inductively coupled plasma tandem mass spectrometry(ICP-MS/MS),a new strategy for the quantification of 45 ultra-trace impurity elements in high-purity magnesium was proposed.The results indicated that the limits of detection(LOD)were in the range of 0.02–18.5 ng L^(−1);the LODs of the challenging non-metallic elements Si and S were 18.5 and 12.2 ng L^(−1),respectively;and the LODs of all the other analytes were less than 10 ng L^(−1).Even under hot plasma conditions,LODs of alkali metal elements were also less than 5 ng L^(−1).The spike recovery of each analyte was 93.6%–107%,and the relative standard deviation(RSD)was 3.2%–6.9%,respectively.At a 95%level of confidence,no significant differences were found between the results obtained under the optimal conditions for the analyte with the developed method and the measurement results of SF-ICP-MS.The developed method indicated low LOD,high sample throughput,and complete interference elimination,demonstrating a new avenue for the rapid determination of ultra-trace elements in high-purity magnesium.
基金supported by the National Magnetic Confinement Fusion Energy R&D Program of China (Nos.2019YFE03030004 and 2022YFE03100001)。
文摘Tearing modes may play an important role in the density limit disruption.The Magnetohydrodynamic(MHD)code CLT with impurity modules is used to study the tearing mode excited and driven by impurity radiation.The impurity radiation can lead to plasma contraction and local enhancement of the current density.When the locally enhanced region of the current density approaches to the resonance surface,the tearing mode can be excited,even if the tearing mode is stable in the initial equilibrium.Through a scan of the initial atomic number(Z)and impurity concentrations,it is found that impurities with different Z values exhibit similar behaviors in the radiation-driven tearing mode.The impurity radiation can drive tearing mode growth through temperature cooling near the resonance surface,and there exists a linear relationship between the temperature perturbation caused by impurity radiation and the linear growth rate of the tearing mode.Additionally,the impurity can promote the growth of magnetic islands through the radiation cooling inside the magnetic island,and there exists a correlation between the initial parameters of impurity and the width of the saturated magnetic island.
基金Project(51164010)supported by the National Natural Science Foundation of ChinaProject(2010GZC0048)supported by the Natural Science Foundation of Jiangxi Province,China
文摘Ion-absorbed rare-earth ore is an important mineral resource which is widely extracted by in-situ leaching process. And such process generates a significant amount of impurities such as aluminum and iron ions in leaching solution simultaneously. The surface characteristics and interactions by infrared spectroscopy and X-ray diffraction were studied to optimize the leaching conditions. It is found that the environment-friendly depressant LG-01 can react with the impurity ions through the formation of a new complex on the surface of leaching residues. Thus, it reduces significantly the concentration of impurity ions in leaching solution and improves the leaching rate of rare-earth ore. Moreover, a leaching rate of 95.6% and an impurity removal rate of 92% have been achieved under the optimized conditions.
基金Projects(51464006,51164001)supported by the National Natural Science Foundation of ChinaProject(GJR201147-12)supported by Guangxi Higher Education Institutes Talent Highland Innovation Team Scheme,ChinaProject(2012MDZD038)supported by the Key Scientific Research Project of Guangxi University for Nationalities,China
文摘Six kinds of galena with different impurities were synthesized and the effects of impurities on the floatability of galena were investigated. The thermodynamic and kinetic parameters on the galena surface were measured using microcalorimetry, and the adsorption configuration and energy of butyl xanthate on the surfaces of galena with different impurities were simulated by density functional theory. Flotation experiments showed that Ag and Bi significantly promoted the recovery of galena, while Zn, Sb, Mn, and Cu reduced the recovery of the flotation. Microthermokinetic results indicated that the absolute value of xanthate adsorption heat was directly proportional to the flotation recovery of galena. Adsorption heat and reaction rate coefficients of xanthate on galena containing Ag or Bi were larger than those on pure galena, but smaller on galena containing Cu or Sb. Additionally, the relationship between the heat of unsaturated adsorption of xanthate and the adsorption energy of impurity atom on galena surface was investigated.
基金Project (50864001) supported by the National Natural Science Foundation of China
文摘The electronic property of pyrite supercell containing As,Se,Te,Co or Ni hetero atoms were calculated using density functional theory（DFT）,and the reactivities of pyrite with oxygen and xanthate were discussed by frontier orbital methods.The cell volume expands due to the presence of impurity.Co and Ni mainly affect the bands near Fermi levels,while As mainly affects the shallow and deep valence bands,and Se and Te mainly affect the deep valence bands.Electronic density analysis suggests that there exists a strong covalent interaction between hetero atom and its surrounding atoms.By frontier orbital calculation,it is suggested that As,Co and Ni have greater influence on the HOMO and LUMO of pyrite than Se and Te.In addition,pyrite containing As,Co or Ni is easier to oxidize by oxygen than pyrite containing Se or Te,and pyrite containing Co or Ni has greater interaction with collector.These are in agreement with the observed pyrite practice.
基金Project(51374253)supported by the National Natural Science Foundation of China
文摘Effect of sulfur impurity on coke reactivity was investigated by simulating petroleum coke with low-impurity pitch coke and impurities doping. And its mechanism was discussed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The results show that sulfur has strong catalysis on both air and CO2 reactivity of coke in the case of no other impurity interference. Its catalysis is probably realized by triggering organic sulfur→H2S→SO2→COS and elemental sulfur (Sx)→SO2 and organic sulfur→H2S→COS→Sx→C2S→COS reaction systems during coke?O2 and coke?CO2 reactions, respectively, which are partly circular with functions of increasing carbon consumption and enlarging coke specific surface area.
文摘We report herein the synthesis of impurity B of Flumazenil via demethylation, benzyl protection, cyclization and debenzylation from 7-methoxyl-3,4-dihydro-4-methyl-2H-1,4-benzo-diazepine-2,5（1H）-dione. The structure of impurity B of Flurnazenil was confirmed by 1n N/V[R, 13C NMR and HRMS, and the overall yield was 29.3%. The finding will be helpful for optimizing the synthetic process and quality control of Flumazenil.
文摘Modifying effect and mechanism of trace rare earth on Fe(Si) rich impurity phases in commercial purity aluminum were studied with the aids of SEM, EDAX, TEM, etc. It is found that Ce rich mixed rare earth (RE) is an effective modifying agent, which makes the coarse Fe rich impurity phases transform into complex compounds of tiny, sphere/short stick form, thus improving mechanical properties of this material; its modifying mechanism is in that RE gathering in front of solid/liquid interface enters into the impurity phases, forming complex (AlFeSiRE) compounds; or is adsorbed in the impurity phases surface, impeding the growth of impurity phases; however, excessive RE will result in the increasing of RE compounds (secondary phases), and plasticity reduction of this material. Therefore, its addition amount should be less than 0 07% (mass fraction).
文摘We consider a three-electron system in the Impurity Hubbard model with a coupling between nearest-neighbors. Our research aim consists of studying the structure of essential spectrum and discrete spectra of the energy operator of three-electron systems in the impurity Hubbard model in the quartet state of the system in a <em>v</em>-dimensional lattice. We have reduced the study of the spectrum of the three-electron quartet state operator in the impurity Hubbard model to the study of the spectrum of a simpler operator. We proved the essential spectra of the three-electron systems in the Impurity Hubbard model in the quartet state is the union of no more than six segments, and the discrete spectrum of the system is consists of no more than four eigenvalues.
基金supported by NIFS budgets,KOBF031,ULFF004,KUHR032partly supported by JSPS KAKENHI 18K04999+2 种基金JSPS-CAS Bilateral Joint Research Projects,“Control of wall recycling on metallic plasma-facing materials in fusion reactor”2019-2022,(No.GJHZ201984)the Chinese Academy of Sciences President’s International Fellowship Initiative Grant No.2024VMB0003 in FY2023the U.S.Department Of Energy under Contract No.DE-AC02-09CH11466 with Princeton University。
文摘In the Large Helical Device(LHD),diborane(B2H6)is used as a standard boron source for boronization,which is assisted by helium glow discharges.In 2019,a new Impurity Powder Dropper(IPD)system was installed and is under evaluation as a real-time wall conditioning technique.In the LHD,which is a large-sized heliotron device,an additional helium(He)glow discharge cleaning(GDC)after boronization was operated for a reduction in hydrogen recycling from the coated boron layers.This operational time of 3 h was determined by spectroscopic data during glow discharges.A flat hydrogen profile is obtained on the top surface of the coated boron on the specimen exposed to boronization.The results suggest a reduction in hydrogen at the top surface by He-GDC.Trapped oxygen in coated boron was obtained by boronization,and the coated boron,which has boron-oxide,on the first wall by B-IPD was also shown.Considering the difference in coating areas between B2H6 boronization and B-IPD operation,it would be most effective to use the IPD and B2H6 boronization coating together for optimized wall conditioning.
基金supported by National Natural Science Foundation of China (Grant Nos.11575247,11605243,11575244)National Magnetic Confinement Fusion Science Program of China (Grant No.2014GB124006)
文摘Plasma radiation characteristics in EAST argon（Ar） gas and neon（Ne） gas seeding experiments are studied.The radiation profiles reconstructed from the fast bolometer measurement data by tomography method are compared with the ones got from the simulation program based on corona model.And the simulation results coincide roughly with the experimental data.For Ar seeding discharges,the substantial enhanced radiations can be generally observed in the edge areas at normalized radius ρ_（pol）~0.7–0.9,while the enhanced regions are more outer for Ne seeding discharges.The influence of seeded Ar gas on the core radiation is related to the injected position.In discharges with LSN divertor configuration,the Ar ions can permeate into the core region more easily when being injected from the opposite upper divertor ports.In USN divertor configuration,the W impurity sputtered from the upper divertor target plates are observed to be an important contributor to the increase of the core radiation no matter impurity seeding from any ports.The maximum radiated power fractions f_（rad）（P_（rad）/P_（heat）） about 60%–70% have been achieved in the recent EAST experimental campaign in 2015–2016.
基金financially supported by the National Key R&D Program of China(No.2016YFB0301100)the National Natural Science Foundation of China(No.51571043)the Fundamental Research Funds for the Central Universities(Nos.2018CDJDCL0019,cqu2018CDHB1A08 and 2018CDGFCL0005).
文摘The effect of impurity element Fe on corrosion behavior of AZ61 magnesium alloys in various states has been investigated by immersion test and hydrogen evolution measurements in 3.5% sodium chloride solution.The corrosion rate is found to relay on the impurity Fe concentration in the alloys and decreases with decreasing Fe content.When Fe content drops from 150 ppm to 10 ppm,the corresponding corrosion rates under as-cast and solution treatment conditions are reduced from 8.54 mm/a and 8.61 mm/a to 2.54 mm/a and 0.21 mm/a,respectively.The corrosion pattern of the AZ61 alloys is the localized corrosion,and the galvanic couples are formed among the impurity particles,second-phase particles and the matrix.The Fe impurity particles tend to act as main cathodic to form micro-galvanic cell with the α-Mg matrix,which is harmful for corrosion resistance of AZ61 alloy.
基金National Key New Drug R&D Program Foundation of China(Grant No.2009ZX09313-027)
文摘In order to determine the optimal mode of capillary electrophoresis for the impurity control of β-lactam antibiotics, different modes and various electrophoresis conditions for the separation of impurities were compared.The results showed that micellar electrokinetic capillary chromatography（MEKC） was the optimal separation mode for the impurity profiling of β-lactam antibiotics.In MEKC,not only the common R and S isomers,Δ-2 andΔ-3 isomers,and Z and E isomers,but also the impurities of β-lactam antibiotics could be well separated compared with the capillary zone electrophoresis.Therefore,MECK is the first choice for the separation of impurities of β-lactam antibiotics with capillary electrophoresis（CE）.The optimal separation could be achieved in MEKC by optimizing the pH and the concentrations of buffered saline,micelles and organic solvent（methanol） in running buffer.
基金Project(51504036) supported by the National Natural Science Foundation of ChinaProject(2012CBA01207) supported by the National Basic Research Program of ChinaProject(2011AA03A409) supported by the National High-Tech Research and Development Program of China
文摘The distribution rules of impurities in distilled terbium metal were investigated by vacuum distillation purificationexperiment and theoretical analysis.It is found that Ti impurity in distilled terbium is220mg/kg in the initial stage of the distillationpurification,increases slowly in the middle stage,and increases rapidly in the last stage,reaching2260mg/kg,and the modifiedseparation coefficient of Ti is1/19.02.The diffusion of the impurity Ti in liquid metal can reach a quasi-equilibrium state in theinitial stage of distillation purification and the calculated results agree well with experimental results;the distribution profile ofimpurity Cu is opposite to Ti,being380mg/kg in the initial stage,decreasing linearly to290mg/kg in the last stage,and themodified separation coefficient is17.99,and the theoretical calculated results are inconsistent with the experimental result.
基金supported by the National Natural Science Foundation of China(Nos.11832019,11472313,11572355,and 11705264)the Science and Technology Plan Project of Guangdong Province(No.2020A0505020005)+2 种基金the Fundamental Research Funds for the Central Universities(No.19lgpy298)the State Key Laboratory of Powder MetallurgyCentral South University,Changsha,China。
文摘Grain boundaries(GBs)have critical influences on the stability and properties of various materials.In this study,first-principles calculations were performed to determine the effects of four metallic impurities(Ni,Al,Bi,and Pb)and three nonmetallic impurities(H,O,and N)on the GBs of silicon carbide(SiC),using the ∑5(210)GBs as models.The GB energy and segregation energy(SE)were calculated to identify the effects of impurities on the GB stability.Electronic interactions considerably influenced the bonding effects of SiC.The formation of weak bonds resulted in the corrosion and embrittlement of GBs.The co-segregation of Bi,Pb,and O was also investigated in detail.
