Electron emission plays a dominant role in plasma-cathode interactions and is a key factor in many plasma phenomena and industrial applications.It is necessary to illustrate the various electron emission mechanisms an...Electron emission plays a dominant role in plasma-cathode interactions and is a key factor in many plasma phenomena and industrial applications.It is necessary to illustrate the various electron emission mechanisms and the corresponding applicable description models to evaluate their impacts on discharge properties.In this study,detailed expressions of the simplified formulas valid for field emission to thermo-field emission to thermionic emission typically used in the numerical simulation are proposed,and the corresponding application ranges are determined in the framework of the Murphy-Good theory,which is commonly regarded as the general model and to be accurate in the full range of conditions of the validity of the theory.Dimensionless parameterization was used to evaluate the emission current density of the Murphy-Good formula,and a deviation factor was defined to obtain the application ranges for different work functions(2.5‒5 eV),cathode temperatures(300‒6000 K),and emitted electric fields(10^(5) to 10^(10) V·m^(-1)).The deviation factor was shown to be a nonmonotonic function of the three parameters.A comparative study of particle number densities in atmospheric gas discharge with a tungsten cathode was performed based on the one-dimensional implicit particle-in-cell(PIC)with the Monte Carlo collision(MCC)method according to the aforementioned application ranges.It was found that small differences in emission current density can lead to variations in the distributions of particle number density due to changes in the collisional environment.This study provides a theoretical basis for selecting emission models for subsequent numerical simulations.展开更多
A 4 MeV RF linear accelerator for electron beam irradiation applications has been developed at the PBP-CMU Electron Linac Laboratory,Thailand.The system has been reengineered using a decommissioned medical linear acce...A 4 MeV RF linear accelerator for electron beam irradiation applications has been developed at the PBP-CMU Electron Linac Laboratory,Thailand.The system has been reengineered using a decommissioned medical linear accelerator.The main components include a thermionic DC electron gun,an RF linear accelerator,a beam diagnostic chamber,and a beam exit window for electron beam irradiation.Therefore,reengineering must be performed based on the characteristics of the electron beam and its dynamics throughout the system.In this study,the electron beam current density emitted from the cathode was calculated based on the thermionic emission theory,and the result was used to produce the electron beam distribution in the gun using CST Studio Suite^(■)software.The properties of the electron beam and its acceleration in the linear accelerator and downstream diagnostic section were studied using the ASTRA electron beam dynamics simulation code,with the aim of producing an electron beam with an average energy of 4 MeV at the linear accelerator exit.The transverse beam profile and electron deposition dose in the ambient environment were calculated using Geant4 Monte Carlo simulation software to estimate the beam performance for the irradiation experiments.The parameters studied can be used as guidelines for machine operation and future experimental plans.展开更多
The increasing use of light alloys owing to their high performance makes magnesium alloys very attractive for the use in automotive and biomedical applications.However,it is well known that magnesium and its alloys ha...The increasing use of light alloys owing to their high performance makes magnesium alloys very attractive for the use in automotive and biomedical applications.However,it is well known that magnesium and its alloys have poor corrosion resistance in different atmospheric and aqueous environments.As a means of improving corrosion resistance through the microstructure modification,electron beam processing(EBP)was applied on the as-cast AZ91 magnesium alloy.To evaluate the microstructure influence on the corrosion-resistant,the EB processed samples underwent a solution heat treatment and an artificial aging heat treatment.Four different obtained microstructures were investigated by standard microscopy and electrochemical corrosion tests to evaluate the microstructure and its effects on the corrosion resistance of AZ91 alloy.The EBPed specimens show a significant microstructure refinement and homogenous distribution ofβ-phase at the grain boundaries surrounded by supersaturatedα-Mg which acts as a barrier against corrosion.The electrochemical corrosion test of the samples immersed in 3.5 wt%NaCl after 4 weeks indicates that the EBP improves the corrosion resistance of the alloy due to the nobler corrosion potential of supersaturated a-Mg and more stable protective hydroxide films compared to the heat-treated and as-cast conditions.展开更多
Building cyber-physical system(CPS) models of machine tools is a key technology for intelligent manufacturing. The massive electronic data from a computer numerical control(CNC) system during the work processes of a C...Building cyber-physical system(CPS) models of machine tools is a key technology for intelligent manufacturing. The massive electronic data from a computer numerical control(CNC) system during the work processes of a CNC machine tool is the main source of the big data on which a CPS model is established. In this work-process model, a method based on instruction domain is applied to analyze the electronic big data, and a quantitative description of the numerical control(NC) processes is built according to the G code of the processes. Utilizing the instruction domain, a work-process CPS model is established on the basis of the accurate, real-time mapping of the manufacturing tasks, resources, and status of the CNC machine tool. Using such models, case studies are conducted on intelligent-machining applications, such as the optimization of NC processing parameters and the health assurance of CNC machine tools.展开更多
Halogenated aromatic compounds have attracted increasing concerns due to their toxicity and persistency in the environment, and dehalogenation is one of the promising treatment and detoxification methods. Herein, we s...Halogenated aromatic compounds have attracted increasing concerns due to their toxicity and persistency in the environment, and dehalogenation is one of the promising treatment and detoxification methods. Herein, we systematically studied the debromination efficiency and mechanism of para-bromophenol（4-BP） by a recently developed UV/sulfite process. 4-BP underwent rapid degradation with the kinetics accelerated with the increasing sulfite concentration, pH（6.1–10） and temperature, whereas inhibited by dissolved oxygen and organic solvents. The apparent activation energy was estimated to be 27.8 kJ/mol. The degradation mechanism and pathways of 4-BP were explored by employing N2O and nitrate as the electron scavengers and liquid chromatography/mass spectrometry to identify the intermediates. 4-BP degradation proceeded via at least two pathways including direct photolysis and hydrated electron-induced debromination. The contributions of both pathways were distinguished by quantifying the quantum yields of 4-BP via direct photolysis and hydrated electron production in the system. 4-BP could be readily completely debrominated with all the substituted Br released as Br-, and the degradation pathways were also proposed. This study would shed new light on the efficient dehalogenation of brominated aromatics by using the UV/sulfite process.展开更多
The effect of de-trapping on the carrier transport process in the CdZ＇nTe detector is studied by laser beam-induced transient current （LBIC） measurement. Trapping time, de-trapping time, and mobility for electrons ...The effect of de-trapping on the carrier transport process in the CdZ＇nTe detector is studied by laser beam-induced transient current （LBIC） measurement. Trapping time, de-trapping time, and mobility for electrons are determined directly from transient waveforms under various bias voltages. The results suggest that an electric field strengthens the capture and emission effects in trap center, which is associated with field-assisted capture and the Poole-Frenkel effect, respectively. The electron mobility is calculated to be 950 cm2/V-s and the corresponding electron mobility-lifetime product is found to be 1.32 × 10-3 cm2/V by a modified Hecht equation with considering the surface recombination effect. It is concluded that the trapping time and de-trapping time obtained from LBIC measurement provide direct information concerning the transport process.展开更多
The important features of the rescattering trajectories in strong field ionization process such as the cutoff of the return energy at 3.17Up and that of the final energy at 10Up are obtained, based on the adiabatic ap...The important features of the rescattering trajectories in strong field ionization process such as the cutoff of the return energy at 3.17Up and that of the final energy at 10Up are obtained, based on the adiabatic approximation in which the initial momentum of the electron is assumed to be zero. We theoretically study the nonadiabatic effect by assuming a nonzero initial momentum on the rescattering trajectories based on the semiclassical simpleman model. We show that the nonzero initial momentum will modify both the maximal return energy at collision and the final energy after backward scattering, but in different ways for odd and even number of return trajectories. The energies are increased for even number of returns but are decreased for odd number of returns when the nonzero （positive or negative） initial momentum is applied.展开更多
Together with the mechanical properties,the degradation rate is an important factor for biodegradable implants.The ZKX50 Mg alloy is a suitable candidate to be used as a biodegradable implant due to its favorable bioc...Together with the mechanical properties,the degradation rate is an important factor for biodegradable implants.The ZKX50 Mg alloy is a suitable candidate to be used as a biodegradable implant due to its favorable biocompatibility and mechanical properties.Current research investigates the degradation rate and corrosion behavior of the ZKX50 as a function of the microstructure constituents and their morphology.Since grain refinement is the main strengthening mechanism for the ZKX50,the effect of the microstructure refinement on the corrosion rate was studied by applying electron beam processing(EBP)and friction stir processing(FSP)on the ZKX50 cast alloy.To study the effect of the microstructure constituents and their morphology a subsequent solution heat treatment(HT)was applied to the processed samples.The results show that the EBP and FSP lead to a uniform and remarkably refined microstructure of the ZKX50 alloy and homogeneous distribution of the intermetallic phases.The results of electrochemical corrosion tests together with the microstructure characterization show that microgalvanic corrosion is the predominant mechanism that occurs between the Ca2Mg6Zn3 intermetallic phase andα-Mg matrix.According to the results attained through the electrochemical tests,the EBPed-HT ZKX50 alloy shows higher corrosion resistance compared to all other conditions immersed in 0.5 wt.%NaCl solution.The dissolution and spheroidizing of Ca2Mg6Zn3 particles during the solution heat treatment provides higher corrosion resistance mainly by decreasing the microgalvanic corrosion.The microstructure of the heat-treated samples does not show a significant grain coarsening which can degrade the enhancement of the mechanical properties achieved by the EBP and FSP.展开更多
The electron excitation processes of H(1s)+He(1s^(2))→H(2s/2p)+He(1s^(2))are studied in impact energy range of 20-2000 e V/u by using the quantum-mechanical molecular orbital close-coupling(QMOCC)method.Total and sta...The electron excitation processes of H(1s)+He(1s^(2))→H(2s/2p)+He(1s^(2))are studied in impact energy range of 20-2000 e V/u by using the quantum-mechanical molecular orbital close-coupling(QMOCC)method.Total and state-selective cross sections have been obtained and compared with the available theoretical and experimental results.The results agree well with available measurements in the overlapping energy regions overall.The comparison of our results with other theoretical calculations further demonstrates the importance of considering a sufficient number of channels.The datasets presented in this paper,including the excitation cross sections,are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00083.展开更多
It was found that the free Fe in the melted zone of the as—cast Nd_2Fe_(14)B alloy could be dissolved by Iaser/electron beam.The growth direction of Nd_2Fe_(14)B grains is nearly perpendicular to the sur- face of the...It was found that the free Fe in the melted zone of the as—cast Nd_2Fe_(14)B alloy could be dissolved by Iaser/electron beam.The growth direction of Nd_2Fe_(14)B grains is nearly perpendicular to the sur- face of the samples.EDX examination showed that Fe element was homogeneously distributed in the melted zone.Results presented in this paper have giv- en hint to remove free Fe in as—cast Nd_2Fe_(14)B alloy.展开更多
Nitrogen-doped carbon(N-C)materials have demonstrated exceptional performances in activating peroxymonosulfate(PMS)for environmental remediation.However,accommodating higher nitrogen contents remains challenging in N-...Nitrogen-doped carbon(N-C)materials have demonstrated exceptional performances in activating peroxymonosulfate(PMS)for environmental remediation.However,accommodating higher nitrogen contents remains challenging in N-C due to the thermodynamic instability of C-N skeleton.In this study,we proposed an innovative epitaxial growth approach to synthesize two-dimensional N-C nanosheets.Leveraging the abundant amino groups supplied by the polymer dots as growing sites,we successfully attained a high nitrogen level and spontaneously introduced abundant structural defects in the carbon framework.The resulting N-C nanosheets exhibited outstanding catalytic activity for the activation of PMS toward selective oxidation of diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate(1,4-DHP)into diethyl2,6-dimethylpyridine-3,5-dicarboxylate,which serves as a valuable intermediate in the synthesis of various pharmaceutical compounds.Comprehensive experimental and characterization investigations verified that the nitrogen sites and defects are the primary active sites for PMS activation and selective oxidation of 1,4-DHP.This work offered an efficient approach for the fabrication of high-nitrogen-loading carbon materials for catalytic oxidation reactions.展开更多
Herein,a diatomite biomorphic Si-O doped carbon-based catalyst(DB-SiOC)was prepared using natura mineral diatomite as the silicon source and porous template.The results showed that the metal-free DB SiOC catalyst exhi...Herein,a diatomite biomorphic Si-O doped carbon-based catalyst(DB-SiOC)was prepared using natura mineral diatomite as the silicon source and porous template.The results showed that the metal-free DB SiOC catalyst exhibited ultrafast oxidation towards chlorophenol(CP)via peroxymonosulfate(PMS)activa tion,which was almost one order of magnitudes than most of carbon-based catalysts.The DB-SiOC/PMS system also showed the high ability to resist the interference of environmental matrix.The radicals(^(·)OH and SO_(4)^(·–))exhibited a very small contribution to the CP oxidation while the electron transfer processe(ETP)played the major role in the DB-SiOC/PMS system.The electron shuttles from the electron-donating CP molecules to the adjacent DB-SiOC/PMS^(*)could be efficiently triggered via Si-O bonds as bridges,mak ing it possible for ultrafast oxidation of CP.In addition,the hollow-disc shaped DB-Si OC provided the biomorphic DE structures with abundant pores for enriching the PMS and pollutants,thus further ac celerating the oxidation reaction.This work provided a new routine for the fabrication of Si-O doped carbon-based catalysts with excellent Fenton-like catalytic activity,which would greatly promote thei application prospects in Fenton-like systems.展开更多
CONSPECTUS:Solution-processed electronics have shown promise in cost-effective manufacturing,but face challenges in precisely and accurately placing electronic materials.Traditional methods,such as photolithography wi...CONSPECTUS:Solution-processed electronics have shown promise in cost-effective manufacturing,but face challenges in precisely and accurately placing electronic materials.Traditional methods,such as photolithography with photoresists,involve complex steps that can damage electronic materials.Alternatives such as orthogonal patterning and inkjet printing are limited by the difficulty of finding compatible chemicals that do not dissolve underlying layers,while nanoimprinting lacks compatibility with high-throughput processes and suffers from poor chemical robustness.Conventional photo-cross-linking approaches have used organic or polymeric agents to pattern electronic layers,but the consecutive application of photo-cross-linking processes for patterning and stacking of multiple electronic materials typically led to degradation of the intrinsic properties of the materials.展开更多
In groundwater,deep soil layer,sediment,the widespread of xenobiotic organic contaminants(XOCs)have been leading to the concern of human health and eco-environment safety,which calls for a better understanding on the ...In groundwater,deep soil layer,sediment,the widespread of xenobiotic organic contaminants(XOCs)have been leading to the concern of human health and eco-environment safety,which calls for a better understanding on the fate and remediation of XOCs in anoxic matrices.In the absence of oxygen,bacteria utilize various oxidized substances,e.g.nitrate,sulphate,metallic(hydr)oxides,humic substance,as terminal electron acceptors(TEAs)to fuel anaerobic XOCs degradation.Although there have been increasing anaerobic biodegradation studies focusing on species identification,degrading pathways,community dynamics,systematic reviews on the underlying mechanism of anaerobic contaminants removal from the perspective of electron flow are limited.In this review,we provide the insight on anaerobic biodegradation from electrons aspect-electron production,transport,and consumption.The mechanism of the coupling between TEAs reduction and pollutants degradation is deconstructed in the level of community,pure culture,and cellular biochemistry.Hereby,relevant strategies to promote anaerobic biodegradation are proposed for guiding to an efficient XOCs bioremediation.展开更多
The photo-induced electron transfer reactions of anthracene with N,N -diethylaniline(DEA) and phenothiazine(PTZ) occur in the membrane phase of a Triton X-100/ n -C 10 H 21 OH(1-decanol)/H 2O microemulsion. DEA and PT...The photo-induced electron transfer reactions of anthracene with N,N -diethylaniline(DEA) and phenothiazine(PTZ) occur in the membrane phase of a Triton X-100/ n -C 10 H 21 OH(1-decanol)/H 2O microemulsion. DEA and PTZ exist in the membrane phase of the microemulsion. Anthracene exists in the oil continuous phase of the W/O microemulsion and in the oil core and membrane phase of the O/W microemulsion.展开更多
The electrochemical carbon dioxide reduction reaction(CO_(2)RR),which can produce value-added chemical feedstocks,is a proton-coupled-electron process with sluggish kinetics.Thus,highly efficient,cheap catalysts are u...The electrochemical carbon dioxide reduction reaction(CO_(2)RR),which can produce value-added chemical feedstocks,is a proton-coupled-electron process with sluggish kinetics.Thus,highly efficient,cheap catalysts are urgently required.Transition metal oxides such as CoO_(x),FeO_(x),and NiO_(x)are low-cost,low toxicity,and abundant materials for a wide range of electrochemical reactions,but are almost inert for CO_(2)RR.Here,we report for the first time that nitrogen doped carbon nanotubes(N-CNT)have a surprising activation effect on the activity and selectivity of transition metal-oxide(MO_(x)where M=Fe,Ni,and Co)nanoclusters for CO_(2)RR.MO_(x)supported on N-CNT,MO_(x)/N-CNT,achieves a CO yield of 2.6–2.8 mmol cm−2 min−1 at an overpotential of−0.55 V,which is two orders of magnitude higher than MO_(x)supported on acid treated CNTs(MO_(x)/O-CNT)and four times higher than pristine N-CNT.The faraday efficiency for electrochemical CO_(2)-to-CO conversion is as high as 90.3%at overpotential of 0.44 V.Both in-situ XAS measurements and DFT calculations disclose that MO_(x)nanoclusters can be hydrated in CO_(2)saturated KHCO_(3),and the N defects of N-CNT effectively stabilize these metal hydroxyl species under carbon dioxide reduction reaction conditions,which can split the water molecules and provide local protons to inhibit the poisoning of active sites under carbon dioxide reduction reaction conditions.展开更多
Digital image stabilization technique plays important roles in video surveillance and object acquisition.Many useful electronic image stabilization algorithms have been studied.A real-time algorithm is proposed based ...Digital image stabilization technique plays important roles in video surveillance and object acquisition.Many useful electronic image stabilization algorithms have been studied.A real-time algorithm is proposed based on field image gray projection which enables the regional odd and even field image to be projected into x and y directions and thus to get the regional gray projection curves in x and y directions,respectively.For the odd field image channel,motion parameters can be estimated via iterative minimum absolute difference based on two successive field image regional gray projection curves.Then motion compensations can be obtained after using the Kalman filter method.Finally,the odd field image is adjusted according to the compensations.In the mean time,motion compensation is applied to the even field image channel with the odd field image gray projection curves of the current frame.By minimizing absolute difference between odd and even field image gray projection curves of the current frame,the inter-field motion parameters can be estimated.Therefore,the even field image can be adjusted by combining the inter-field motion parameters and the odd field compensations.Finally,the stabilized image sequence can be obtained by synthesizing the adjusted odd and even field images.Experimental results show that the proposed algorithm can run in real-time and have a good stabilization performance.In addition,image blurring can be improved.展开更多
The nonradiative charge-transfer processes of Be3+(1s)/B4+(1s)colliding with He(1s2)are investigated by the quantum-mechanical molecular orbital close-coupling(QMOCC)method from 10 eV/u to 1800 eV/u.Total and state-se...The nonradiative charge-transfer processes of Be3+(1s)/B4+(1s)colliding with He(1s2)are investigated by the quantum-mechanical molecular orbital close-coupling(QMOCC)method from 10 eV/u to 1800 eV/u.Total and state-selective cross sections are obtained and compared with other results available.Although the incident ions have the same number of electrons and collide with the same target,their cross sections are different due to the differences in molecular structure.For Be3+(1s)+He(1s2),only single-electron-capture(SEC)states are important and the total cross sections have a broad maximum around E=150 eV/u.While for B4+(1s)+He(1s2),both the SEC and double-electron-capture(DEC)processes are important,and the total SEC and DEC cross sections decrease rapidly with the energy decreasing.展开更多
Comprehensive Summary Cathode interlayers(CILs)play an essential role in achieving efficient organic solar cells(OSCs).However,the electronic structure at the electrode/CIL/active layer interfaces and the underlying m...Comprehensive Summary Cathode interlayers(CILs)play an essential role in achieving efficient organic solar cells(OSCs).However,the electronic structure at the electrode/CIL/active layer interfaces and the underlying mechanisms for electron collection remain unclear,which becomes a major obstacle to develop high-performance CILs.Herein,we investigate the relationship of the electron collection abilities of four cross-linked and n-doped CILs(c-NDI:P0,c-NDI:P1,c-NDI:P2,c-NDI:P3)with their electronic structure of space charge region at heterojunction interface.By accurately calculating the depletion region width according to the barrier height,doping density and permittivity,we put forward that the optimal thickness of CIL should be consistent with the depletion region width to realize the minimum energy loss.As a result,the depletion region width is largely reduced from 13 nm to 0.8 nm at the indium tin oxide(ITO)/c-NDI:P0 interface,resulting in a decent PCE of 17.7%for the corresponding inverted OSCs.展开更多
基金supported in part by National Natural Science Foundation of China(Nos.52176087 and 52277164)Foundation for Innovative Research Groups of National Natural Science Foundation of China(No.51721004)+1 种基金Scientific Research Program Funded by Shaanxi Provincial Education Department(No.23JP115)Youth Innovation Team of Shaanxi Universities,in part by the Natural Science Basic Research Plan of Shaanxi Province(Nos.2021J Z-48 and 2020JM-462).
文摘Electron emission plays a dominant role in plasma-cathode interactions and is a key factor in many plasma phenomena and industrial applications.It is necessary to illustrate the various electron emission mechanisms and the corresponding applicable description models to evaluate their impacts on discharge properties.In this study,detailed expressions of the simplified formulas valid for field emission to thermo-field emission to thermionic emission typically used in the numerical simulation are proposed,and the corresponding application ranges are determined in the framework of the Murphy-Good theory,which is commonly regarded as the general model and to be accurate in the full range of conditions of the validity of the theory.Dimensionless parameterization was used to evaluate the emission current density of the Murphy-Good formula,and a deviation factor was defined to obtain the application ranges for different work functions(2.5‒5 eV),cathode temperatures(300‒6000 K),and emitted electric fields(10^(5) to 10^(10) V·m^(-1)).The deviation factor was shown to be a nonmonotonic function of the three parameters.A comparative study of particle number densities in atmospheric gas discharge with a tungsten cathode was performed based on the one-dimensional implicit particle-in-cell(PIC)with the Monte Carlo collision(MCC)method according to the aforementioned application ranges.It was found that small differences in emission current density can lead to variations in the distributions of particle number density due to changes in the collisional environment.This study provides a theoretical basis for selecting emission models for subsequent numerical simulations.
基金supported by Chiang Mai University for providing infrastructure and the NSRF via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation[grant number B05F650022]for the software CST Studio Suite^(■)2023Financial support for the reengineering and commissioning of the accelerator system was provided by the Thailand Center of Excellence in Physics(ThEP Center),Science and Technology Park Chiang Mai University(CMU STeP)。
文摘A 4 MeV RF linear accelerator for electron beam irradiation applications has been developed at the PBP-CMU Electron Linac Laboratory,Thailand.The system has been reengineered using a decommissioned medical linear accelerator.The main components include a thermionic DC electron gun,an RF linear accelerator,a beam diagnostic chamber,and a beam exit window for electron beam irradiation.Therefore,reengineering must be performed based on the characteristics of the electron beam and its dynamics throughout the system.In this study,the electron beam current density emitted from the cathode was calculated based on the thermionic emission theory,and the result was used to produce the electron beam distribution in the gun using CST Studio Suite^(■)software.The properties of the electron beam and its acceleration in the linear accelerator and downstream diagnostic section were studied using the ASTRA electron beam dynamics simulation code,with the aim of producing an electron beam with an average energy of 4 MeV at the linear accelerator exit.The transverse beam profile and electron deposition dose in the ambient environment were calculated using Geant4 Monte Carlo simulation software to estimate the beam performance for the irradiation experiments.The parameters studied can be used as guidelines for machine operation and future experimental plans.
文摘The increasing use of light alloys owing to their high performance makes magnesium alloys very attractive for the use in automotive and biomedical applications.However,it is well known that magnesium and its alloys have poor corrosion resistance in different atmospheric and aqueous environments.As a means of improving corrosion resistance through the microstructure modification,electron beam processing(EBP)was applied on the as-cast AZ91 magnesium alloy.To evaluate the microstructure influence on the corrosion-resistant,the EB processed samples underwent a solution heat treatment and an artificial aging heat treatment.Four different obtained microstructures were investigated by standard microscopy and electrochemical corrosion tests to evaluate the microstructure and its effects on the corrosion resistance of AZ91 alloy.The EBPed specimens show a significant microstructure refinement and homogenous distribution ofβ-phase at the grain boundaries surrounded by supersaturatedα-Mg which acts as a barrier against corrosion.The electrochemical corrosion test of the samples immersed in 3.5 wt%NaCl after 4 weeks indicates that the EBP improves the corrosion resistance of the alloy due to the nobler corrosion potential of supersaturated a-Mg and more stable protective hydroxide films compared to the heat-treated and as-cast conditions.
基金support of the studies is from the National Major Scientific and Technological Special Project for "Development and comprehensive verification of complete products of open high-end CNC system, servo device and motor" (2012ZX04001012)
文摘Building cyber-physical system(CPS) models of machine tools is a key technology for intelligent manufacturing. The massive electronic data from a computer numerical control(CNC) system during the work processes of a CNC machine tool is the main source of the big data on which a CPS model is established. In this work-process model, a method based on instruction domain is applied to analyze the electronic big data, and a quantitative description of the numerical control(NC) processes is built according to the G code of the processes. Utilizing the instruction domain, a work-process CPS model is established on the basis of the accurate, real-time mapping of the manufacturing tasks, resources, and status of the CNC machine tool. Using such models, case studies are conducted on intelligent-machining applications, such as the optimization of NC processing parameters and the health assurance of CNC machine tools.
基金supported by the National Natural Science Foundation of China(No.21307057)the Natural Science Foundation of Jiangsu Province(No.BK20130577)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China(SRFDP,No.20130091120014)the Fundamental Research Funds for the Central Universities(No.20620140128)
文摘Halogenated aromatic compounds have attracted increasing concerns due to their toxicity and persistency in the environment, and dehalogenation is one of the promising treatment and detoxification methods. Herein, we systematically studied the debromination efficiency and mechanism of para-bromophenol（4-BP） by a recently developed UV/sulfite process. 4-BP underwent rapid degradation with the kinetics accelerated with the increasing sulfite concentration, pH（6.1–10） and temperature, whereas inhibited by dissolved oxygen and organic solvents. The apparent activation energy was estimated to be 27.8 kJ/mol. The degradation mechanism and pathways of 4-BP were explored by employing N2O and nitrate as the electron scavengers and liquid chromatography/mass spectrometry to identify the intermediates. 4-BP degradation proceeded via at least two pathways including direct photolysis and hydrated electron-induced debromination. The contributions of both pathways were distinguished by quantifying the quantum yields of 4-BP via direct photolysis and hydrated electron production in the system. 4-BP could be readily completely debrominated with all the substituted Br released as Br-, and the degradation pathways were also proposed. This study would shed new light on the efficient dehalogenation of brominated aromatics by using the UV/sulfite process.
基金Project supported by the National Instrumentation Program,China(Grant No.2011YQ040082)the National Natural Science Foundation of China(Grant Nos.61274081,51372205,and 51202197)+1 种基金the National 973 Project of China(Grant No.2011CB610400),the China Postdoctoral Science Foundation(Grant No.2014M550509)the 111 Project of China(Grant No.B08040)
文摘The effect of de-trapping on the carrier transport process in the CdZ＇nTe detector is studied by laser beam-induced transient current （LBIC） measurement. Trapping time, de-trapping time, and mobility for electrons are determined directly from transient waveforms under various bias voltages. The results suggest that an electric field strengthens the capture and emission effects in trap center, which is associated with field-assisted capture and the Poole-Frenkel effect, respectively. The electron mobility is calculated to be 950 cm2/V-s and the corresponding electron mobility-lifetime product is found to be 1.32 × 10-3 cm2/V by a modified Hecht equation with considering the surface recombination effect. It is concluded that the trapping time and de-trapping time obtained from LBIC measurement provide direct information concerning the transport process.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11425414 and 11504215the Scientific Research Training Program of Shanxi University
文摘The important features of the rescattering trajectories in strong field ionization process such as the cutoff of the return energy at 3.17Up and that of the final energy at 10Up are obtained, based on the adiabatic approximation in which the initial momentum of the electron is assumed to be zero. We theoretically study the nonadiabatic effect by assuming a nonzero initial momentum on the rescattering trajectories based on the semiclassical simpleman model. We show that the nonzero initial momentum will modify both the maximal return energy at collision and the final energy after backward scattering, but in different ways for odd and even number of return trajectories. The energies are increased for even number of returns but are decreased for odd number of returns when the nonzero （positive or negative） initial momentum is applied.
文摘Together with the mechanical properties,the degradation rate is an important factor for biodegradable implants.The ZKX50 Mg alloy is a suitable candidate to be used as a biodegradable implant due to its favorable biocompatibility and mechanical properties.Current research investigates the degradation rate and corrosion behavior of the ZKX50 as a function of the microstructure constituents and their morphology.Since grain refinement is the main strengthening mechanism for the ZKX50,the effect of the microstructure refinement on the corrosion rate was studied by applying electron beam processing(EBP)and friction stir processing(FSP)on the ZKX50 cast alloy.To study the effect of the microstructure constituents and their morphology a subsequent solution heat treatment(HT)was applied to the processed samples.The results show that the EBP and FSP lead to a uniform and remarkably refined microstructure of the ZKX50 alloy and homogeneous distribution of the intermetallic phases.The results of electrochemical corrosion tests together with the microstructure characterization show that microgalvanic corrosion is the predominant mechanism that occurs between the Ca2Mg6Zn3 intermetallic phase andα-Mg matrix.According to the results attained through the electrochemical tests,the EBPed-HT ZKX50 alloy shows higher corrosion resistance compared to all other conditions immersed in 0.5 wt.%NaCl solution.The dissolution and spheroidizing of Ca2Mg6Zn3 particles during the solution heat treatment provides higher corrosion resistance mainly by decreasing the microgalvanic corrosion.The microstructure of the heat-treated samples does not show a significant grain coarsening which can degrade the enhancement of the mechanical properties achieved by the EBP and FSP.
基金supported by the National Natural Science Foundation of China(Grant Nos.12204288,11934004,and 12274040)
文摘The electron excitation processes of H(1s)+He(1s^(2))→H(2s/2p)+He(1s^(2))are studied in impact energy range of 20-2000 e V/u by using the quantum-mechanical molecular orbital close-coupling(QMOCC)method.Total and state-selective cross sections have been obtained and compared with the available theoretical and experimental results.The results agree well with available measurements in the overlapping energy regions overall.The comparison of our results with other theoretical calculations further demonstrates the importance of considering a sufficient number of channels.The datasets presented in this paper,including the excitation cross sections,are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00083.
文摘It was found that the free Fe in the melted zone of the as—cast Nd_2Fe_(14)B alloy could be dissolved by Iaser/electron beam.The growth direction of Nd_2Fe_(14)B grains is nearly perpendicular to the sur- face of the samples.EDX examination showed that Fe element was homogeneously distributed in the melted zone.Results presented in this paper have giv- en hint to remove free Fe in as—cast Nd_2Fe_(14)B alloy.
基金the financial support from Australian Research Council under DECRA Scheme(No.DE210100253)merit SXR beamline from Australian Nuclear Science and Technology Organization(ANSTO,No.AS231/SXR/19680)。
文摘Nitrogen-doped carbon(N-C)materials have demonstrated exceptional performances in activating peroxymonosulfate(PMS)for environmental remediation.However,accommodating higher nitrogen contents remains challenging in N-C due to the thermodynamic instability of C-N skeleton.In this study,we proposed an innovative epitaxial growth approach to synthesize two-dimensional N-C nanosheets.Leveraging the abundant amino groups supplied by the polymer dots as growing sites,we successfully attained a high nitrogen level and spontaneously introduced abundant structural defects in the carbon framework.The resulting N-C nanosheets exhibited outstanding catalytic activity for the activation of PMS toward selective oxidation of diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate(1,4-DHP)into diethyl2,6-dimethylpyridine-3,5-dicarboxylate,which serves as a valuable intermediate in the synthesis of various pharmaceutical compounds.Comprehensive experimental and characterization investigations verified that the nitrogen sites and defects are the primary active sites for PMS activation and selective oxidation of 1,4-DHP.This work offered an efficient approach for the fabrication of high-nitrogen-loading carbon materials for catalytic oxidation reactions.
基金supported by National Natural Science Foundation of China(No.52170086)Shandong Provincial Excellent Youth(No.ZR2022YQ47)。
文摘Herein,a diatomite biomorphic Si-O doped carbon-based catalyst(DB-SiOC)was prepared using natura mineral diatomite as the silicon source and porous template.The results showed that the metal-free DB SiOC catalyst exhibited ultrafast oxidation towards chlorophenol(CP)via peroxymonosulfate(PMS)activa tion,which was almost one order of magnitudes than most of carbon-based catalysts.The DB-SiOC/PMS system also showed the high ability to resist the interference of environmental matrix.The radicals(^(·)OH and SO_(4)^(·–))exhibited a very small contribution to the CP oxidation while the electron transfer processe(ETP)played the major role in the DB-SiOC/PMS system.The electron shuttles from the electron-donating CP molecules to the adjacent DB-SiOC/PMS^(*)could be efficiently triggered via Si-O bonds as bridges,mak ing it possible for ultrafast oxidation of CP.In addition,the hollow-disc shaped DB-Si OC provided the biomorphic DE structures with abundant pores for enriching the PMS and pollutants,thus further ac celerating the oxidation reaction.This work provided a new routine for the fabrication of Si-O doped carbon-based catalysts with excellent Fenton-like catalytic activity,which would greatly promote thei application prospects in Fenton-like systems.
基金supported by the Samsung Research Funding&Incubation Center of Samsung Electronics under project number SRFC-MA1901-51by the National Research Foundation of Korea(NRF)grant funded by the Ministry of Science,ICT,and Future Planning under project number(NRF 2023R1A2C3006550,RS-2023-00244309).
文摘CONSPECTUS:Solution-processed electronics have shown promise in cost-effective manufacturing,but face challenges in precisely and accurately placing electronic materials.Traditional methods,such as photolithography with photoresists,involve complex steps that can damage electronic materials.Alternatives such as orthogonal patterning and inkjet printing are limited by the difficulty of finding compatible chemicals that do not dissolve underlying layers,while nanoimprinting lacks compatibility with high-throughput processes and suffers from poor chemical robustness.Conventional photo-cross-linking approaches have used organic or polymeric agents to pattern electronic layers,but the consecutive application of photo-cross-linking processes for patterning and stacking of multiple electronic materials typically led to degradation of the intrinsic properties of the materials.
基金supported by National Key R&D Program of China(Nos.2019YFC1805803)the National Natural Science Foundation of China(Nos.91951108,41907273 and 31670507)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA23010400)Science and Technology Service Network Initiative of the Chinese Academy of Sciences(Grant KFJ-STS-ZDTP-064)。
文摘In groundwater,deep soil layer,sediment,the widespread of xenobiotic organic contaminants(XOCs)have been leading to the concern of human health and eco-environment safety,which calls for a better understanding on the fate and remediation of XOCs in anoxic matrices.In the absence of oxygen,bacteria utilize various oxidized substances,e.g.nitrate,sulphate,metallic(hydr)oxides,humic substance,as terminal electron acceptors(TEAs)to fuel anaerobic XOCs degradation.Although there have been increasing anaerobic biodegradation studies focusing on species identification,degrading pathways,community dynamics,systematic reviews on the underlying mechanism of anaerobic contaminants removal from the perspective of electron flow are limited.In this review,we provide the insight on anaerobic biodegradation from electrons aspect-electron production,transport,and consumption.The mechanism of the coupling between TEAs reduction and pollutants degradation is deconstructed in the level of community,pure culture,and cellular biochemistry.Hereby,relevant strategies to promote anaerobic biodegradation are proposed for guiding to an efficient XOCs bioremediation.
基金Supported by the National Natural Science Foundation of China( No.2 0 0 730 38,2 0 2 330 10 )
文摘The photo-induced electron transfer reactions of anthracene with N,N -diethylaniline(DEA) and phenothiazine(PTZ) occur in the membrane phase of a Triton X-100/ n -C 10 H 21 OH(1-decanol)/H 2O microemulsion. DEA and PTZ exist in the membrane phase of the microemulsion. Anthracene exists in the oil continuous phase of the W/O microemulsion and in the oil core and membrane phase of the O/W microemulsion.
基金Y.C.and J.C.are contributed equally to the paper.Project supported by the National Natural Science Foundation of China (U19A2017)the Fundamental Research Funds for the Central South University and the Australian Research Council (DP180100731 and DP180100568)。
文摘The electrochemical carbon dioxide reduction reaction(CO_(2)RR),which can produce value-added chemical feedstocks,is a proton-coupled-electron process with sluggish kinetics.Thus,highly efficient,cheap catalysts are urgently required.Transition metal oxides such as CoO_(x),FeO_(x),and NiO_(x)are low-cost,low toxicity,and abundant materials for a wide range of electrochemical reactions,but are almost inert for CO_(2)RR.Here,we report for the first time that nitrogen doped carbon nanotubes(N-CNT)have a surprising activation effect on the activity and selectivity of transition metal-oxide(MO_(x)where M=Fe,Ni,and Co)nanoclusters for CO_(2)RR.MO_(x)supported on N-CNT,MO_(x)/N-CNT,achieves a CO yield of 2.6–2.8 mmol cm−2 min−1 at an overpotential of−0.55 V,which is two orders of magnitude higher than MO_(x)supported on acid treated CNTs(MO_(x)/O-CNT)and four times higher than pristine N-CNT.The faraday efficiency for electrochemical CO_(2)-to-CO conversion is as high as 90.3%at overpotential of 0.44 V.Both in-situ XAS measurements and DFT calculations disclose that MO_(x)nanoclusters can be hydrated in CO_(2)saturated KHCO_(3),and the N defects of N-CNT effectively stabilize these metal hydroxyl species under carbon dioxide reduction reaction conditions,which can split the water molecules and provide local protons to inhibit the poisoning of active sites under carbon dioxide reduction reaction conditions.
基金supported by the National Natural Science Foundation of China(6110118561302145)
文摘Digital image stabilization technique plays important roles in video surveillance and object acquisition.Many useful electronic image stabilization algorithms have been studied.A real-time algorithm is proposed based on field image gray projection which enables the regional odd and even field image to be projected into x and y directions and thus to get the regional gray projection curves in x and y directions,respectively.For the odd field image channel,motion parameters can be estimated via iterative minimum absolute difference based on two successive field image regional gray projection curves.Then motion compensations can be obtained after using the Kalman filter method.Finally,the odd field image is adjusted according to the compensations.In the mean time,motion compensation is applied to the even field image channel with the odd field image gray projection curves of the current frame.By minimizing absolute difference between odd and even field image gray projection curves of the current frame,the inter-field motion parameters can be estimated.Therefore,the even field image can be adjusted by combining the inter-field motion parameters and the odd field compensations.Finally,the stabilized image sequence can be obtained by synthesizing the adjusted odd and even field images.Experimental results show that the proposed algorithm can run in real-time and have a good stabilization performance.In addition,image blurring can be improved.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774344,11474033,and 11574326)the National Key Research and Development Program of China(Grant No.2017YFA0402300).
文摘The nonradiative charge-transfer processes of Be3+(1s)/B4+(1s)colliding with He(1s2)are investigated by the quantum-mechanical molecular orbital close-coupling(QMOCC)method from 10 eV/u to 1800 eV/u.Total and state-selective cross sections are obtained and compared with other results available.Although the incident ions have the same number of electrons and collide with the same target,their cross sections are different due to the differences in molecular structure.For Be3+(1s)+He(1s2),only single-electron-capture(SEC)states are important and the total cross sections have a broad maximum around E=150 eV/u.While for B4+(1s)+He(1s2),both the SEC and double-electron-capture(DEC)processes are important,and the total SEC and DEC cross sections decrease rapidly with the energy decreasing.
基金financial support from Guangdong Major Project of Basic and Applied Basic Research(No.2019B030302007)Bureau of International Cooperation Chinese Academy of Sciences(121111KYSB20200043)+1 种基金National Natural Science Foundation of China(NSFC,21835006,51961135103)B.X.would like to acknowledge the financial support from Fundamental Research Funds for the Central Universities(buctrc202140).
文摘Comprehensive Summary Cathode interlayers(CILs)play an essential role in achieving efficient organic solar cells(OSCs).However,the electronic structure at the electrode/CIL/active layer interfaces and the underlying mechanisms for electron collection remain unclear,which becomes a major obstacle to develop high-performance CILs.Herein,we investigate the relationship of the electron collection abilities of four cross-linked and n-doped CILs(c-NDI:P0,c-NDI:P1,c-NDI:P2,c-NDI:P3)with their electronic structure of space charge region at heterojunction interface.By accurately calculating the depletion region width according to the barrier height,doping density and permittivity,we put forward that the optimal thickness of CIL should be consistent with the depletion region width to realize the minimum energy loss.As a result,the depletion region width is largely reduced from 13 nm to 0.8 nm at the indium tin oxide(ITO)/c-NDI:P0 interface,resulting in a decent PCE of 17.7%for the corresponding inverted OSCs.
