This study investigates the application of Gurney and flight of fragment equations,typically used to predict metal fragment velocities,in modeling the water jet behavior.Three shotgun cartridge sizes were used as the ...This study investigates the application of Gurney and flight of fragment equations,typically used to predict metal fragment velocities,in modeling the water jet behavior.Three shotgun cartridge sizes were used as the energy source:2.59 g,5.83 g,and 7.13 g.Two configurations were tested:standard(full-barrel water load)and"negative 8"(partial water load).High-speed footage captured water column velocities,and Gurney models,including infinitely tamped and open-faced configurations,combined with the flight of fragment model were used to assess prediction accuracy.Results showed charge strength significantly affects water column velocity,with higher strengths yielding greater stability and velocity retention over distance.The infinitely tamped Gurney model closely predicted experimental velocities,deviating by as little as 1.4%for standard charges and 2.8% for negative 8 charges.Additionally,interesting dynamics such as a 1-2°rise in jet height and the rear overtaking the front was observed.These findings have significant implications for optimizing PAN disruptors and enhancing performance in high-velocity fluid applications and explosive breaching systems.展开更多
Understanding the adsorption behavior of heavy metals and metalloids on clay minerals is essential for remediating heavy metal-contaminated soils.The adsorption of heavy metals and metalloids on illite(001)and sodium ...Understanding the adsorption behavior of heavy metals and metalloids on clay minerals is essential for remediating heavy metal-contaminated soils.The adsorption of heavy metals and metalloids on illite(001)and sodium montmorillonite(Na-MMT)(001)surfaces was investigated using first-principles calculations in this study,especially As atom and H_(3)AsO_(3) molecule.The adsorption energies of the As atom were−1.94 eV on the illite(001)and−0.56 eV on the Na-MMT(001),whereas,the adsorption energies of the H_(3)AsO_(3) molecule were−1.40 eV on illite(001)and−1.01 eV on Na-MMT(001).The above results indicate that the adsorption was more energetically favorable on illite(001).Additionally,compared to Na-MMT(001),there were more significant interactions between the atoms/molecules on the illite(001).After As atom and H_(3)AsO_(3) molecule adsorption,the electrons were transferred from mineral surface atoms to the adsorbates on both illite(001)and Na-MMT(001)surfaces.Moreover,the adsorption of As atom on illite(001)and Na-MMT(001)surfaces were more energy favorable compared to Hg,Cd,and Cr atoms.Overall,this work provides new insights into the adsorption behavior of As atoms and As molecules on illite and Na-MMT.The results indicate that illite rich soils are more prone to contamination by arsenic compared to soils primarily composed of Na-MMT minerals.展开更多
The paper presents analysis of the performance and the internal flow behaviour in the vaned diffuser of a radial flow pump using PIV(particle image velocimetry)and pressure probe traverses.PIV measurements have alread...The paper presents analysis of the performance and the internal flow behaviour in the vaned diffuser of a radial flow pump using PIV(particle image velocimetry)and pressure probe traverses.PIV measurements have already been performed at middle height inside one diffuser channel passage for a given speed of rotation and various mass flow rates.These results have been already presented in several previous communications.New experiments have been performed using a three-hole pressure probe traverses from hub to shroud diffuser width at different radial locations between the two diffuser geometrical throats.Numerical simulations are also realized with the commercial codes Star CCM+7.02.011 and CFX.Frozen rotor and fully unsteady calculations of the whole pump have been performed.Comparisons between numerical results,previous experimental PIV results and new probe traverses one's are presented and discussed for one mass flow rate.In this respect,a first attempt to take into account fluid leakages between the rotating and fixed part of the pump has been checked since it may affects the real flow structure inside the diffuser.展开更多
Using the first-principles calculations based on density functional theory(DFT),the structure stability,electronic and some optical properties of C and N doped cubic ZrO2(c-ZrO2) in 24-atom systems were investigated.I...Using the first-principles calculations based on density functional theory(DFT),the structure stability,electronic and some optical properties of C and N doped cubic ZrO2(c-ZrO2) in 24-atom systems were investigated.It is found from the formation energies calculations that N ions are easier to be doped into c-ZrO2 than C ions.The electronic structure results show that Zr8O15C and Zr8O15N systems are semiconductors with the band gap of 2.3 eV and 2.8 eV,respectively,which are lower than that of the pure ZrO2(3.349 eV).And optical properties results depict that anion doping,especially C adding,can enhance the static dielectric function,visible and ultraviolet light absorption and reflecting ability of c-ZrO2 crystal.展开更多
The dielectric constant(DC)is one of the key properties for detection of threat materials such as Improvised Explosive Devices(IEDs).In the present paper,the density functional theory(DFT)as well as ab-initio approach...The dielectric constant(DC)is one of the key properties for detection of threat materials such as Improvised Explosive Devices(IEDs).In the present paper,the density functional theory(DFT)as well as ab-initio approaches are used to explore effective methods to predict dielectric constants of a series of 12 energetic materials(EMs)for which experimental data needed to experimentally determine the dielectric constant(refractive indices)are available.These include military grades energetic materials,nitro and peroxide compounds,and the widely used nitroglycerin.Ab-initio and DFT calculations are conducted.In order to calculate dielectric constant values of materials,potential DFT functional combined with basis sets are considered for testing.Accuracy of the calculations are compared to experimental data listed in the scientific literature,and time required for calculations are both evaluated and discussed.The best functional/basis set combinations among those tested are CAM-B3LYP and AUG-ccpVDZm,which provide great results,with accuracy deviations below 5%when calculated results are compared to experimental data.展开更多
Surfactant molecules, when dispersed in solution, have been shown to spontaneously form aggregates. Our previous studies on molecular dynamics(MD) calculations have shown that ionic sodium dodecyl sulfate molecules qu...Surfactant molecules, when dispersed in solution, have been shown to spontaneously form aggregates. Our previous studies on molecular dynamics(MD) calculations have shown that ionic sodium dodecyl sulfate molecules quickly aggregated even when the aggregation number is small. The aggregation rate, however, decreased for larger aggregation numbers. In addition, studies have shown that micelle formation was not completed even after a 100 ns-long MD run(Chem. Phys. Lett. 2016, 646, 36). Herein, we analyze the free energy change of micelle formation based on chemical species model combined with molecular dynamics calculations. First, the free energy landscape of the aggregation, ?G_(i+j)^+, where two aggregates with sizes i and j associate to form the(i + j)-mer, was investigated using the free energy of micelle formation of the i-mer, G_i^+, which was obtained through MD calculations. The calculated ?G_(i+j)^+ was negative for all the aggregations where the sum of DS ions in the two aggregates was 60 or less. From the viewpoint of chemical equilibrium, aggregation to the stable micelle is desired. Further, the free energy profile along possible aggregation pathways was investigated, starting from small aggregates and ending with the complete thermodynamically stable micelles in solution. The free energy profiles, G(l, k), of the aggregates at l-th aggregation path and k-th state were evaluated by the formation free energy ∑_in_i( l,k)G_i^+ and the free energy of mixing ∑_in_i( l,k)k_BTln( n_i( l,k)/n( l,k)), where ni(l, k) is the number of i-mer in the system at the l-th i aggregation path and k-th state, with n(l,k)= ∑_n_i( l,k). All the aggregation pathways were obtained from the initial i state of 12 pentamers to the stable micelle with i = 60. All the calculated G(l, k) values monotonically decreased with increasing k. This indicates that there are no free energy barriers along the pathways. Hence, the slowdown is not due to the thermodynamic stability of the aggregates, but rather the kinetics that inhibit the association of the fragments. The time required for a collision between aggregates, one of the kinetic factors, was evaluated using the fast passage time, t_(FPT). The calculated t_(FPT) was about 20 ns for the aggregates with N = 31. Therefore, if aggregation is a diffusion-controlled process, it should be completed within the 100 ns-simulation. However, aggregation does not occur due to the free energy barrier between the aggregates, that is, the repulsive force acting on them. This may be caused by electrostatic repulsions produced by the overlap of the electric double layers, which are formed by the negative charge of the hydrophilic groups and counter sodium ions on the surface of the aggregates.展开更多
Employing first-principles calculations based on density functional theory,we establish the high-pressure phase diagrams for XeN_(3) and XeN_(6),and investigate their electronic and superconducting properties under hi...Employing first-principles calculations based on density functional theory,we establish the high-pressure phase diagrams for XeN_(3) and XeN_(6),and investigate their electronic and superconducting properties under high pressure.Our results indicate that at their respective lowest stable pressures,XeN_(3) is a direct-bandgap semiconductor with a bandgap of 1.64 eV,whereas XeN_(6) is an indirect-bandgap material with a bandgap of 1.45 eV,which transitions to a metallic state as pressure increases.The density of states analysis reveals significant hybridization between N-2p and Xe-5p orbitals,with contributions to the Fermi level predominantly from these orbitals.Additionally,it was found that XeN_(6) becomes a superconductor under high pressures after metallization,with its superconducting transition temperature showing a linear dependence on pressure.展开更多
High-entropy alloys(HEAs)have emerged as promising candidates for energy structural materials(ESMs)due to their superior mechanical properties and compositional flexibility.However,their corrosion resistance in contac...High-entropy alloys(HEAs)have emerged as promising candidates for energy structural materials(ESMs)due to their superior mechanical properties and compositional flexibility.However,their corrosion resistance in contact with energetic materials,particularly NTO,a widely used insensitive high explosive,remains insufficiently understood.In this study,a series of ZrTiHfTax HEAs with varying Ta contents were fabricated via vacuum arc melting to explore the effect of Ta content on microstructural evolution and corrosion resistance in aqueous NTO solution.X-ray diffraction(XRD)and transmission electron microscopy(TEM)analyses revealed a composition-induced phase transformation from a dual-phase HCP+BCC structure at low Ta content to a single-phase BCC structure at higher Ta concentrations.Electrochemical measurements demonstrated that increasing Ta content markedly enhanced corrosion resistance;the corrosion current density of the Ta1.00 HEA was 44.57%of that of the Ta0.25 HEA.Moreover,X-ray photoelectron spectroscopy(XPS)and time-of-flight secondary ion mass spectrometry(ToF-SIMS)indicated that higher Ta content facilitated the formation of a denser and more compact passive film with reduced defect density.Density functional theory(DFT)calculations further revealed that the passive layer provides dual protection effects by physically hindering H+/NTO−ingress and chemically suppressing nitro group dissociation and substrate oxidation.This work offers fundamental insights into the corrosion protection mechanisms of HEAs in NTO-containing environments and provides valuable guidance for the rational design of corrosion-resistant HEAs.展开更多
The adsorptive denitrification performance of MIL-101(Cr)-0.5 toward pyridine,aniline or quinoline in simulated fuels with basic nitrogen content of 1732μg/g was evaluated separately.Furthermore,the effects of adsorp...The adsorptive denitrification performance of MIL-101(Cr)-0.5 toward pyridine,aniline or quinoline in simulated fuels with basic nitrogen content of 1732μg/g was evaluated separately.Furthermore,the effects of adsorption temperature,adsorption time and adsorbent dosage on their adsorptive denitrification performance were systematically investigated.The experimental results demonstrated that under a fixed adsorbent dosage of 0.05 g and a simulated fuel volume of 10 mL,the optimal removal efficiency for aniline was achieved at 30℃ within 30 min,whereas higher temperatures and longer times(40℃and 40 min)were required for effective removal of pyridine and quinoline.Density Functional Theory(DFT)calculations were conducted via Materials Studio(MS)software to study the adsorptive denitrification mechanism of MIL-101(Cr)toward these three basic nitrogen-containing compounds.The simulation calculation results revealed that the interaction between pyridine and MIL-101(Cr)primarily involved coordination adsorption.In contrast,the interaction between aniline or quinoline and MIL-101(Cr)proceeded mainly through coordination,with additional contributions fromπ-complexation and hydrogen bonding.The overall adsorption strength order is pyridine>aniline>quinoline.During the adsorption process,pyridine and quinoline transfer electrons to the MIL-101(Cr)surface through the H→C→N→Cr^(3+)pathway,while aniline transfers electrons to the MIL-101(Cr)surface through various pathways,including N→Cr^(3+),N→C→Cr^(3+)and N→H→O.Furthermore,adsorption kinetics studies indicated that the adsorption processes for all three basic nitrogen-containing compounds followed the quasi second order kinetic models.The experimental results on the effect of benzene on the adsorptive denitrification performance of MIL-101(Cr)-0.5 demonstrated that benzene exerted a more significant impact on the adsorption of aniline and quinoline.Finally,the adsorbent was regenerated using ethanol washing.It was found that MIL-101(Cr)-0.5 retained stable denitrification performance after two regeneration cycles.展开更多
The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor ...The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.展开更多
Existing numerical methods for complex composites, such as multiscale simulation and neural network algorithms, face significant limitations. Multiscale techniques are often prohibitively expensive for large models, w...Existing numerical methods for complex composites, such as multiscale simulation and neural network algorithms, face significant limitations. Multiscale techniques are often prohibitively expensive for large models, while neural networks struggle to represent underlying microscopic material properties. To overcome these challenges, a meso-micro scale numerical method using a virtual node approach is developed in this study. A Wbraid/Al/Epoxy functional structural material is fabricated, and a representative periodic unit cell is identified based on its architecture. The complex structure is then discretized into nodes, and mechanical interactions are governed by pre-defined computation rules. This virtual node method is systematically compared against both multiscale simulation and a neural network algorithm, with validation provided through mechanical experiments. The results demonstrate that the nodal operation strategy significantly reduces computational resource requirements. By quantifying microscopic bonding with coefficients, explicit interface treatment is avoided, granting the method strong adaptability to lattice materials. The method can simulate extremely complex structures using parameters from simple tests and is suited for large systems. Compared to three-point bending experiments, errors for multiscale, virtual node, and neural network methods were 12.4%, 6.9%, and 34.5%, respectively. Under dynamic compression, the errors were 2.7%, 9.3%, and 15.43%. The virtual node method demonstrated superior accuracy under static conditions, enabling efficient prediction and auxiliary development of complex structural materials.展开更多
Investigating the detonation reaction zone structures of high explosives is significant for understanding detonation reaction mechanism.This study employed an integrated approach combining machine learning prediction,...Investigating the detonation reaction zone structures of high explosives is significant for understanding detonation reaction mechanism.This study employed an integrated approach combining machine learning prediction,theoretical calculation,and experimental characterization to determine the detonation reaction zone width of CL-20-based aluminized explosive.In this study,the detonation reaction zone refers to the reaction zone between the von Neumann(VN)peak and sonic point,which usually means the so-called detonation driving zone(DDZ).For the machine learning prediction,an ensemble model integrating Random Forest and Support Vector Regression was developed to predict the reaction zone width using a dataset of 19 publicly available samples.For the theoretical calculation,the Wood-Kirkwood(W-K)detonation theory model was utilized to implement numerical calculation of the reaction zone structures,incorporating chemical reaction kinetics to describe the detonation reaction progress.In experimental characterization,the Photon Doppler Velocimetry(PDV)was applied with LiF as the optical window to measure the particle velocity profile of detonation products and derive the reaction zone width.The results indicate that the reaction zone width values are 0.25 mm,0.28 mm,and 0.26 mm obtained from machine learning prediction,theoretical calculation,and experimental characterization,respectively.The corresponding velocities at the Chapman-Jouguet(CJ)point are 1,938 m/s,2,047 m/s,and 1,982 m/s,respectively.The maximum relative deviation in reaction zone width among three methods is approximately 7.7%,while that for CJ particle velocity is approximately 3.3%.These results from all three methods agree well within engineering error.This validates the effectiveness of integrating machine learning prediction,theoretical calculation and advanced experimental techniques for studying the detonation reaction zone structures of high explosives.This research provides insights into the detonation reaction mechanism and reaction zone characteristics of CL-20-based aluminized explosive.展开更多
The paper considers the methodology for a comprehensive analysis of the stability of an open pit-dump system,using limit equilibrium(LEM)and finite element(FEM)methods in the Russian CAE(computer-aided engineering)sof...The paper considers the methodology for a comprehensive analysis of the stability of an open pit-dump system,using limit equilibrium(LEM)and finite element(FEM)methods in the Russian CAE(computer-aided engineering)software Fidesys.It briefly highlights the issues of comparing limit equilibrium methods using the VNIMI(Research Institute of Geomechanics and Mine Surveying-Intersectoral Scientific Center"VNIMI")methodology and a specialized software product with numerical methods.The main focus of this study is to compare the results of the stability analysis in the volumetric model of the open pit-dump system using limit equilibrium and finite element methods in the CAE software Fidesys.It was found that,when modeling the combined operation of an open pit-dump system in complex terrain,both methods should be used,as each has its own advantages.The finite element method,for instance,has certain features that are not present in the calculations using the limit equilibrium approach.As a key scientific contribution,this paper introduces an automation program for calculating the stability of open-pit walls using the limit equilibrium method in CAE Fidesys,which was not previously integrated in the original software.The calculations performed with the use of this newly developed module were compared to those obtained from other widely used software solutions available on the market.The findings demonstrate a remarkable level of convergence in the calculation results for all relevant parameters,including the safety factor,localization,instability type,and deformation.The proposed approach i mproves the accuracy of calculati ons and ensures consistency between the higher stress design zones and the actual deformation and fracture patterns.It also enhances the ability to predict the behavior of rock mass when calculating stability parameters for facilities,both during operation and desi gn.展开更多
This study aims to enhance the photocatalytic performance of 2D/2D heterojunctions for NO removal from marine vessel effluents.SnS_(2)/g-C_(3)N_(4) composites were successfully constructed via a facile solvothermal me...This study aims to enhance the photocatalytic performance of 2D/2D heterojunctions for NO removal from marine vessel effluents.SnS_(2)/g-C_(3)N_(4) composites were successfully constructed via a facile solvothermal method,demonstrating a significant improvement in photocatalytic NO removal under visible light irradiation.For high-flux simulated flue gas,the composite with 10%SnS_(2)(denoted as SNCN-10)showed exceptional NO removal efficiency,reaching up to 66.8%,along with excellent reusability over five consecutive cycles.Detailed band structure and density of states(DOS)calculations confirmed the formation of a characteristic heterojunction.Spin-trapping ESR spectroscopy identified·O_(2)^(-)−as the key reactive species driving NO oxidation.Additionally,in situ DRIFT spectroscopy revealed that SNCN-10 facilitated the conversion of NO to nitrate through intermediate species,including bridging nitrite and cis-nitrite(N_(2)O_(2)^(2-)).Kinetic studies further indicated that NO oxidation followed the Langmuir-Hinshelwood(L-H)mechanism.Based on density functional theory(DFT)calculations of free energy changes,a comprehensive reaction pathway for NO oxidation was proposed.These findings provide valuable insights for the development of efficient photocatalytic strategies for NO removal.展开更多
Two new transition-metal coordination polymers,{[Cd(oba)(L)_(2)]·H_(2)O}_n(1)and[Cd(4-nph)(L)_(2)]_n(2)(H_(2)oba=4,4'-oxydibenzoic acid,4-H_(2)nph=4-nitrophthalic acid,L=2,2'-biimidazole),were successfull...Two new transition-metal coordination polymers,{[Cd(oba)(L)_(2)]·H_(2)O}_n(1)and[Cd(4-nph)(L)_(2)]_n(2)(H_(2)oba=4,4'-oxydibenzoic acid,4-H_(2)nph=4-nitrophthalic acid,L=2,2'-biimidazole),were successfully synthesized under hydrothermal conditions and characterized structurally by IR spectroscopy,elemental analyses,single-crystal X-ray diffraction,powder X-ray diffraction,and thermogravimetric analysis.The results of single-crystal X-ray diffraction show that complex 1 presents a 1D zigzag chain structure and further extends to a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.Meanwhile,complex 2 has a zero-dimensional structure and also extends to form a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.In addition,both 1and 2 exhibited luminescent properties in the solid state.Furthermore,quantum chemical calculations were carried out on the"molecular fragments"extracted from the crystal structures of 1 and 2 using the PBE0/LANL2DZ method constructed by the Gaussian 16 program.The calculated values signify a significant covalent interaction between the coordination atoms and the Cd(Ⅱ)ions.CCDC:2332173,1;2332176,2.展开更多
INTERNAL DOSE RESEARCH PAPERS INTDOSKIT:An R-Code for Calculation of Dose Coefficients and Studying Their Uncertainties Bastian Breustedt 1,Niranjan Chavan 2,Thomas Makumbi 2(1.Karlsruhe Institute of Technology,Instit...INTERNAL DOSE RESEARCH PAPERS INTDOSKIT:An R-Code for Calculation of Dose Coefficients and Studying Their Uncertainties Bastian Breustedt 1,Niranjan Chavan 2,Thomas Makumbi 2(1.Karlsruhe Institute of Technology,Institute of Biomedical Engineering(IBT),Fritz-Haber-Weg 1,D-76131 Karlsruhe,Germany;2.Karlsruhe Institute of Technology,Institute for Thermal Energy Technology and Safety(ITES),Hermann-von-Helmholtz-Platz 1,76344 EggensteinLeopoldshafen,Germany)Abstract:An R-code,which allows the calculation of the time dependent activity distribution based on ICRP reference models,the number of decays in a commitment period,and the dose coefficients for tissues and organs of the human body,has been developed.R Language was chosen due to its powerful mathematical and statistical modeling features,as well as its graphical capabilities.展开更多
This study employs density functional theory(DFT)calculations to systematically investigate the B‒H bond dissociation enthalpies(BDEs)of Lewis base‒borane complexes.A rigorous benchmark analysis identified theωB97XD/...This study employs density functional theory(DFT)calculations to systematically investigate the B‒H bond dissociation enthalpies(BDEs)of Lewis base‒borane complexes.A rigorous benchmark analysis identified theωB97XD/cc-pVTZ method as a reliable method for accurate prediction of B–H BDEs.An examination of more than 200 structurally diverse complexes across five major classes revealed that the type of Lewis base significantly influences the BDEs,with the order of amine–borane>phosphine–borane>N-heterocyclic carbene–borane>pyridine–borane.Solventstabilized boranes exhibit the broadest range of BDE values due to the diverse coordination modes of solvent molecules with borane.Further analysis revealed that the BDE values are synergistically affected by skeletal and substituent effects.Notably,a strong linear correlation(R^(2) up to 0.97)between the spin density of boryl radicals and BDEs,except for amine–boranes,provides a robust predictive model.This research enhances the fundamental understanding of B‒H bond dissociation properties in Lewis base–boranes and provides valuable insights for the development of new boron-based methodologies in organic synthesis.展开更多
Al-Cu-Mg-Ag alloys have become a research hotspot because of its good heat resistance.Its excellent mechanical properties are inseparable from the regulation of the structure by researchers.The method of material stru...Al-Cu-Mg-Ag alloys have become a research hotspot because of its good heat resistance.Its excellent mechanical properties are inseparable from the regulation of the structure by researchers.The method of material structure simulation has become more and more perfect.This study employs numerical simulation to investigate the microstructure evolution of Al-Cu-Mg-Ag alloys during solidification with the aim of controlling its structure.The size distribution of Ti-containing particles in an Al-Ti-B master alloy was characterized via microstructure observation,serving as a basis for optimizing the nucleation density parameters for particles of varying radii in the phase field model.The addition of refiner inhibited the growth of dendrites and no longer produced coarse dendrites.With the increase of refiner,the grains gradually tended to form cellular morphology.The refined grains were about 100μm in size.Experimental validation of the simulated as-cast grain morphology was conducted.The samples were observed by metallographic microscope and scanning electron microscope.The addition of refiner had a significant effect on the refinement of the alloy,and the average grain size after refinement was also about 100μm.At the same time,the XRD phase identification of the alloy was carried out.The observation of the microstructure morphology under the scanning electron microscope showed that the precipitated phase was mainly concentrated on the grain boundary.The Al_(2)Cu accounted for about 5%,and the matrix phase FCC accounted for about 95%,which also corresponded well with the simulation results.展开更多
Nitric oxide(NO),which generally originates from vehicle exhaust and industrial flue gases,is one of the most serious air pollutants.In this case,the electrochemical NO reduction reaction(NORR)not only removes the atm...Nitric oxide(NO),which generally originates from vehicle exhaust and industrial flue gases,is one of the most serious air pollutants.In this case,the electrochemical NO reduction reaction(NORR)not only removes the atmospheric pollutant NO but also produces valuable ammonia(NH_(3)).Hence,through the synthesis and modification of Fe_(3)C nanocrystal cata-lysts,the as-obtained optimal sample of Fe_(3)C/C-900 was adopted as the NORR catalyst at ambient conditions.As a result,the Fe_(3)C/C-900 catalyst showed an NH_(3)Faraday efficiency of 76.5%and an NH_(3)yield rate of 177.5μmol·h^(-1)·cm^(-2)at the working potentials of-0.8 and-1.2 V versus reversible hydrogen electrode(vs.RHE),respectively.And it delivered a stable NORR activity during the electrolysis.Moreover,we attribute the high NORR properties of Fe_(3)C/C-900 to two aspects:one is the enhanced intrinsic activity of Fe_(3)C nanocrystals,including the lowering of the energy barrier of rate-limiting step(*NOH→*N)and the inhibition of hydrogen evolution;on the other hand,the favorable dispersion of active components,the effective adsorption of gaseous NO,and the release of liquid NH_(3)products facilitated by the porous carbon substrate.展开更多
基金supported and funded internally through Dr. Catherine Johnson's research funds at Missouri S&T
文摘This study investigates the application of Gurney and flight of fragment equations,typically used to predict metal fragment velocities,in modeling the water jet behavior.Three shotgun cartridge sizes were used as the energy source:2.59 g,5.83 g,and 7.13 g.Two configurations were tested:standard(full-barrel water load)and"negative 8"(partial water load).High-speed footage captured water column velocities,and Gurney models,including infinitely tamped and open-faced configurations,combined with the flight of fragment model were used to assess prediction accuracy.Results showed charge strength significantly affects water column velocity,with higher strengths yielding greater stability and velocity retention over distance.The infinitely tamped Gurney model closely predicted experimental velocities,deviating by as little as 1.4%for standard charges and 2.8% for negative 8 charges.Additionally,interesting dynamics such as a 1-2°rise in jet height and the rear overtaking the front was observed.These findings have significant implications for optimizing PAN disruptors and enhancing performance in high-velocity fluid applications and explosive breaching systems.
基金Project(22376221)supported by the National Natural Science Foundation of ChinaProject(2024JJ2074)supported by the Natural Science Foundation of Hunan Province,ChinaProject(2023QNRC001)supported by the Young Elite Scientists Sponsorship Program by CAST。
文摘Understanding the adsorption behavior of heavy metals and metalloids on clay minerals is essential for remediating heavy metal-contaminated soils.The adsorption of heavy metals and metalloids on illite(001)and sodium montmorillonite(Na-MMT)(001)surfaces was investigated using first-principles calculations in this study,especially As atom and H_(3)AsO_(3) molecule.The adsorption energies of the As atom were−1.94 eV on the illite(001)and−0.56 eV on the Na-MMT(001),whereas,the adsorption energies of the H_(3)AsO_(3) molecule were−1.40 eV on illite(001)and−1.01 eV on Na-MMT(001).The above results indicate that the adsorption was more energetically favorable on illite(001).Additionally,compared to Na-MMT(001),there were more significant interactions between the atoms/molecules on the illite(001).After As atom and H_(3)AsO_(3) molecule adsorption,the electrons were transferred from mineral surface atoms to the adsorbates on both illite(001)and Na-MMT(001)surfaces.Moreover,the adsorption of As atom on illite(001)and Na-MMT(001)surfaces were more energy favorable compared to Hg,Cd,and Cr atoms.Overall,this work provides new insights into the adsorption behavior of As atoms and As molecules on illite and Na-MMT.The results indicate that illite rich soils are more prone to contamination by arsenic compared to soils primarily composed of Na-MMT minerals.
文摘The paper presents analysis of the performance and the internal flow behaviour in the vaned diffuser of a radial flow pump using PIV(particle image velocimetry)and pressure probe traverses.PIV measurements have already been performed at middle height inside one diffuser channel passage for a given speed of rotation and various mass flow rates.These results have been already presented in several previous communications.New experiments have been performed using a three-hole pressure probe traverses from hub to shroud diffuser width at different radial locations between the two diffuser geometrical throats.Numerical simulations are also realized with the commercial codes Star CCM+7.02.011 and CFX.Frozen rotor and fully unsteady calculations of the whole pump have been performed.Comparisons between numerical results,previous experimental PIV results and new probe traverses one's are presented and discussed for one mass flow rate.In this respect,a first attempt to take into account fluid leakages between the rotating and fixed part of the pump has been checked since it may affects the real flow structure inside the diffuser.
基金Project(61172047) supported by the National Natural Science Foundation of China
文摘Using the first-principles calculations based on density functional theory(DFT),the structure stability,electronic and some optical properties of C and N doped cubic ZrO2(c-ZrO2) in 24-atom systems were investigated.It is found from the formation energies calculations that N ions are easier to be doped into c-ZrO2 than C ions.The electronic structure results show that Zr8O15C and Zr8O15N systems are semiconductors with the band gap of 2.3 eV and 2.8 eV,respectively,which are lower than that of the pure ZrO2(3.349 eV).And optical properties results depict that anion doping,especially C adding,can enhance the static dielectric function,visible and ultraviolet light absorption and reflecting ability of c-ZrO2 crystal.
文摘The dielectric constant(DC)is one of the key properties for detection of threat materials such as Improvised Explosive Devices(IEDs).In the present paper,the density functional theory(DFT)as well as ab-initio approaches are used to explore effective methods to predict dielectric constants of a series of 12 energetic materials(EMs)for which experimental data needed to experimentally determine the dielectric constant(refractive indices)are available.These include military grades energetic materials,nitro and peroxide compounds,and the widely used nitroglycerin.Ab-initio and DFT calculations are conducted.In order to calculate dielectric constant values of materials,potential DFT functional combined with basis sets are considered for testing.Accuracy of the calculations are compared to experimental data listed in the scientific literature,and time required for calculations are both evaluated and discussed.The best functional/basis set combinations among those tested are CAM-B3LYP and AUG-ccpVDZm,which provide great results,with accuracy deviations below 5%when calculated results are compared to experimental data.
基金This work was supported by FLAGSHIP2020,MEXT within Priority Study 5(Development of New Fundamental Technologies for High-Efficiency Energy Creation,Conversion/Storage and Use)Using Computational Resources of the K Computer Provided by the RIKEN Advanced
文摘Surfactant molecules, when dispersed in solution, have been shown to spontaneously form aggregates. Our previous studies on molecular dynamics(MD) calculations have shown that ionic sodium dodecyl sulfate molecules quickly aggregated even when the aggregation number is small. The aggregation rate, however, decreased for larger aggregation numbers. In addition, studies have shown that micelle formation was not completed even after a 100 ns-long MD run(Chem. Phys. Lett. 2016, 646, 36). Herein, we analyze the free energy change of micelle formation based on chemical species model combined with molecular dynamics calculations. First, the free energy landscape of the aggregation, ?G_(i+j)^+, where two aggregates with sizes i and j associate to form the(i + j)-mer, was investigated using the free energy of micelle formation of the i-mer, G_i^+, which was obtained through MD calculations. The calculated ?G_(i+j)^+ was negative for all the aggregations where the sum of DS ions in the two aggregates was 60 or less. From the viewpoint of chemical equilibrium, aggregation to the stable micelle is desired. Further, the free energy profile along possible aggregation pathways was investigated, starting from small aggregates and ending with the complete thermodynamically stable micelles in solution. The free energy profiles, G(l, k), of the aggregates at l-th aggregation path and k-th state were evaluated by the formation free energy ∑_in_i( l,k)G_i^+ and the free energy of mixing ∑_in_i( l,k)k_BTln( n_i( l,k)/n( l,k)), where ni(l, k) is the number of i-mer in the system at the l-th i aggregation path and k-th state, with n(l,k)= ∑_n_i( l,k). All the aggregation pathways were obtained from the initial i state of 12 pentamers to the stable micelle with i = 60. All the calculated G(l, k) values monotonically decreased with increasing k. This indicates that there are no free energy barriers along the pathways. Hence, the slowdown is not due to the thermodynamic stability of the aggregates, but rather the kinetics that inhibit the association of the fragments. The time required for a collision between aggregates, one of the kinetic factors, was evaluated using the fast passage time, t_(FPT). The calculated t_(FPT) was about 20 ns for the aggregates with N = 31. Therefore, if aggregation is a diffusion-controlled process, it should be completed within the 100 ns-simulation. However, aggregation does not occur due to the free energy barrier between the aggregates, that is, the repulsive force acting on them. This may be caused by electrostatic repulsions produced by the overlap of the electric double layers, which are formed by the negative charge of the hydrophilic groups and counter sodium ions on the surface of the aggregates.
文摘Employing first-principles calculations based on density functional theory,we establish the high-pressure phase diagrams for XeN_(3) and XeN_(6),and investigate their electronic and superconducting properties under high pressure.Our results indicate that at their respective lowest stable pressures,XeN_(3) is a direct-bandgap semiconductor with a bandgap of 1.64 eV,whereas XeN_(6) is an indirect-bandgap material with a bandgap of 1.45 eV,which transitions to a metallic state as pressure increases.The density of states analysis reveals significant hybridization between N-2p and Xe-5p orbitals,with contributions to the Fermi level predominantly from these orbitals.Additionally,it was found that XeN_(6) becomes a superconductor under high pressures after metallization,with its superconducting transition temperature showing a linear dependence on pressure.
文摘High-entropy alloys(HEAs)have emerged as promising candidates for energy structural materials(ESMs)due to their superior mechanical properties and compositional flexibility.However,their corrosion resistance in contact with energetic materials,particularly NTO,a widely used insensitive high explosive,remains insufficiently understood.In this study,a series of ZrTiHfTax HEAs with varying Ta contents were fabricated via vacuum arc melting to explore the effect of Ta content on microstructural evolution and corrosion resistance in aqueous NTO solution.X-ray diffraction(XRD)and transmission electron microscopy(TEM)analyses revealed a composition-induced phase transformation from a dual-phase HCP+BCC structure at low Ta content to a single-phase BCC structure at higher Ta concentrations.Electrochemical measurements demonstrated that increasing Ta content markedly enhanced corrosion resistance;the corrosion current density of the Ta1.00 HEA was 44.57%of that of the Ta0.25 HEA.Moreover,X-ray photoelectron spectroscopy(XPS)and time-of-flight secondary ion mass spectrometry(ToF-SIMS)indicated that higher Ta content facilitated the formation of a denser and more compact passive film with reduced defect density.Density functional theory(DFT)calculations further revealed that the passive layer provides dual protection effects by physically hindering H+/NTO−ingress and chemically suppressing nitro group dissociation and substrate oxidation.This work offers fundamental insights into the corrosion protection mechanisms of HEAs in NTO-containing environments and provides valuable guidance for the rational design of corrosion-resistant HEAs.
基金Supported by Basic Scientific Research Project of the Liaoning Provincial Department of Education Has Been Unveiled to Facilitate Local Project Funding (JYTMS20230835)Enhanced Scientific Research Project Funded by the Departmentof Higher Education in Liaoning Province (General program)(JYTMS20230852)。
文摘The adsorptive denitrification performance of MIL-101(Cr)-0.5 toward pyridine,aniline or quinoline in simulated fuels with basic nitrogen content of 1732μg/g was evaluated separately.Furthermore,the effects of adsorption temperature,adsorption time and adsorbent dosage on their adsorptive denitrification performance were systematically investigated.The experimental results demonstrated that under a fixed adsorbent dosage of 0.05 g and a simulated fuel volume of 10 mL,the optimal removal efficiency for aniline was achieved at 30℃ within 30 min,whereas higher temperatures and longer times(40℃and 40 min)were required for effective removal of pyridine and quinoline.Density Functional Theory(DFT)calculations were conducted via Materials Studio(MS)software to study the adsorptive denitrification mechanism of MIL-101(Cr)toward these three basic nitrogen-containing compounds.The simulation calculation results revealed that the interaction between pyridine and MIL-101(Cr)primarily involved coordination adsorption.In contrast,the interaction between aniline or quinoline and MIL-101(Cr)proceeded mainly through coordination,with additional contributions fromπ-complexation and hydrogen bonding.The overall adsorption strength order is pyridine>aniline>quinoline.During the adsorption process,pyridine and quinoline transfer electrons to the MIL-101(Cr)surface through the H→C→N→Cr^(3+)pathway,while aniline transfers electrons to the MIL-101(Cr)surface through various pathways,including N→Cr^(3+),N→C→Cr^(3+)and N→H→O.Furthermore,adsorption kinetics studies indicated that the adsorption processes for all three basic nitrogen-containing compounds followed the quasi second order kinetic models.The experimental results on the effect of benzene on the adsorptive denitrification performance of MIL-101(Cr)-0.5 demonstrated that benzene exerted a more significant impact on the adsorption of aniline and quinoline.Finally,the adsorbent was regenerated using ethanol washing.It was found that MIL-101(Cr)-0.5 retained stable denitrification performance after two regeneration cycles.
文摘The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.
文摘Existing numerical methods for complex composites, such as multiscale simulation and neural network algorithms, face significant limitations. Multiscale techniques are often prohibitively expensive for large models, while neural networks struggle to represent underlying microscopic material properties. To overcome these challenges, a meso-micro scale numerical method using a virtual node approach is developed in this study. A Wbraid/Al/Epoxy functional structural material is fabricated, and a representative periodic unit cell is identified based on its architecture. The complex structure is then discretized into nodes, and mechanical interactions are governed by pre-defined computation rules. This virtual node method is systematically compared against both multiscale simulation and a neural network algorithm, with validation provided through mechanical experiments. The results demonstrate that the nodal operation strategy significantly reduces computational resource requirements. By quantifying microscopic bonding with coefficients, explicit interface treatment is avoided, granting the method strong adaptability to lattice materials. The method can simulate extremely complex structures using parameters from simple tests and is suited for large systems. Compared to three-point bending experiments, errors for multiscale, virtual node, and neural network methods were 12.4%, 6.9%, and 34.5%, respectively. Under dynamic compression, the errors were 2.7%, 9.3%, and 15.43%. The virtual node method demonstrated superior accuracy under static conditions, enabling efficient prediction and auxiliary development of complex structural materials.
文摘Investigating the detonation reaction zone structures of high explosives is significant for understanding detonation reaction mechanism.This study employed an integrated approach combining machine learning prediction,theoretical calculation,and experimental characterization to determine the detonation reaction zone width of CL-20-based aluminized explosive.In this study,the detonation reaction zone refers to the reaction zone between the von Neumann(VN)peak and sonic point,which usually means the so-called detonation driving zone(DDZ).For the machine learning prediction,an ensemble model integrating Random Forest and Support Vector Regression was developed to predict the reaction zone width using a dataset of 19 publicly available samples.For the theoretical calculation,the Wood-Kirkwood(W-K)detonation theory model was utilized to implement numerical calculation of the reaction zone structures,incorporating chemical reaction kinetics to describe the detonation reaction progress.In experimental characterization,the Photon Doppler Velocimetry(PDV)was applied with LiF as the optical window to measure the particle velocity profile of detonation products and derive the reaction zone width.The results indicate that the reaction zone width values are 0.25 mm,0.28 mm,and 0.26 mm obtained from machine learning prediction,theoretical calculation,and experimental characterization,respectively.The corresponding velocities at the Chapman-Jouguet(CJ)point are 1,938 m/s,2,047 m/s,and 1,982 m/s,respectively.The maximum relative deviation in reaction zone width among three methods is approximately 7.7%,while that for CJ particle velocity is approximately 3.3%.These results from all three methods agree well within engineering error.This validates the effectiveness of integrating machine learning prediction,theoretical calculation and advanced experimental techniques for studying the detonation reaction zone structures of high explosives.This research provides insights into the detonation reaction mechanism and reaction zone characteristics of CL-20-based aluminized explosive.
文摘The paper considers the methodology for a comprehensive analysis of the stability of an open pit-dump system,using limit equilibrium(LEM)and finite element(FEM)methods in the Russian CAE(computer-aided engineering)software Fidesys.It briefly highlights the issues of comparing limit equilibrium methods using the VNIMI(Research Institute of Geomechanics and Mine Surveying-Intersectoral Scientific Center"VNIMI")methodology and a specialized software product with numerical methods.The main focus of this study is to compare the results of the stability analysis in the volumetric model of the open pit-dump system using limit equilibrium and finite element methods in the CAE software Fidesys.It was found that,when modeling the combined operation of an open pit-dump system in complex terrain,both methods should be used,as each has its own advantages.The finite element method,for instance,has certain features that are not present in the calculations using the limit equilibrium approach.As a key scientific contribution,this paper introduces an automation program for calculating the stability of open-pit walls using the limit equilibrium method in CAE Fidesys,which was not previously integrated in the original software.The calculations performed with the use of this newly developed module were compared to those obtained from other widely used software solutions available on the market.The findings demonstrate a remarkable level of convergence in the calculation results for all relevant parameters,including the safety factor,localization,instability type,and deformation.The proposed approach i mproves the accuracy of calculati ons and ensures consistency between the higher stress design zones and the actual deformation and fracture patterns.It also enhances the ability to predict the behavior of rock mass when calculating stability parameters for facilities,both during operation and desi gn.
基金The project was supported by Natural Science Foundation of Shandong Province(ZR2021MB104)National Natural Science Foundation of China(22078174).
文摘This study aims to enhance the photocatalytic performance of 2D/2D heterojunctions for NO removal from marine vessel effluents.SnS_(2)/g-C_(3)N_(4) composites were successfully constructed via a facile solvothermal method,demonstrating a significant improvement in photocatalytic NO removal under visible light irradiation.For high-flux simulated flue gas,the composite with 10%SnS_(2)(denoted as SNCN-10)showed exceptional NO removal efficiency,reaching up to 66.8%,along with excellent reusability over five consecutive cycles.Detailed band structure and density of states(DOS)calculations confirmed the formation of a characteristic heterojunction.Spin-trapping ESR spectroscopy identified·O_(2)^(-)−as the key reactive species driving NO oxidation.Additionally,in situ DRIFT spectroscopy revealed that SNCN-10 facilitated the conversion of NO to nitrate through intermediate species,including bridging nitrite and cis-nitrite(N_(2)O_(2)^(2-)).Kinetic studies further indicated that NO oxidation followed the Langmuir-Hinshelwood(L-H)mechanism.Based on density functional theory(DFT)calculations of free energy changes,a comprehensive reaction pathway for NO oxidation was proposed.These findings provide valuable insights for the development of efficient photocatalytic strategies for NO removal.
文摘Two new transition-metal coordination polymers,{[Cd(oba)(L)_(2)]·H_(2)O}_n(1)and[Cd(4-nph)(L)_(2)]_n(2)(H_(2)oba=4,4'-oxydibenzoic acid,4-H_(2)nph=4-nitrophthalic acid,L=2,2'-biimidazole),were successfully synthesized under hydrothermal conditions and characterized structurally by IR spectroscopy,elemental analyses,single-crystal X-ray diffraction,powder X-ray diffraction,and thermogravimetric analysis.The results of single-crystal X-ray diffraction show that complex 1 presents a 1D zigzag chain structure and further extends to a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.Meanwhile,complex 2 has a zero-dimensional structure and also extends to form a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.In addition,both 1and 2 exhibited luminescent properties in the solid state.Furthermore,quantum chemical calculations were carried out on the"molecular fragments"extracted from the crystal structures of 1 and 2 using the PBE0/LANL2DZ method constructed by the Gaussian 16 program.The calculated values signify a significant covalent interaction between the coordination atoms and the Cd(Ⅱ)ions.CCDC:2332173,1;2332176,2.
文摘INTERNAL DOSE RESEARCH PAPERS INTDOSKIT:An R-Code for Calculation of Dose Coefficients and Studying Their Uncertainties Bastian Breustedt 1,Niranjan Chavan 2,Thomas Makumbi 2(1.Karlsruhe Institute of Technology,Institute of Biomedical Engineering(IBT),Fritz-Haber-Weg 1,D-76131 Karlsruhe,Germany;2.Karlsruhe Institute of Technology,Institute for Thermal Energy Technology and Safety(ITES),Hermann-von-Helmholtz-Platz 1,76344 EggensteinLeopoldshafen,Germany)Abstract:An R-code,which allows the calculation of the time dependent activity distribution based on ICRP reference models,the number of decays in a commitment period,and the dose coefficients for tissues and organs of the human body,has been developed.R Language was chosen due to its powerful mathematical and statistical modeling features,as well as its graphical capabilities.
基金supported by the USTC Research Funds of the Double First-Class Initiative(YD2060006004,YD2060002027)the National Natural Science Foundation of China(22325107,22171253,22293011).
文摘This study employs density functional theory(DFT)calculations to systematically investigate the B‒H bond dissociation enthalpies(BDEs)of Lewis base‒borane complexes.A rigorous benchmark analysis identified theωB97XD/cc-pVTZ method as a reliable method for accurate prediction of B–H BDEs.An examination of more than 200 structurally diverse complexes across five major classes revealed that the type of Lewis base significantly influences the BDEs,with the order of amine–borane>phosphine–borane>N-heterocyclic carbene–borane>pyridine–borane.Solventstabilized boranes exhibit the broadest range of BDE values due to the diverse coordination modes of solvent molecules with borane.Further analysis revealed that the BDE values are synergistically affected by skeletal and substituent effects.Notably,a strong linear correlation(R^(2) up to 0.97)between the spin density of boryl radicals and BDEs,except for amine–boranes,provides a robust predictive model.This research enhances the fundamental understanding of B‒H bond dissociation properties in Lewis base–boranes and provides valuable insights for the development of new boron-based methodologies in organic synthesis.
文摘Al-Cu-Mg-Ag alloys have become a research hotspot because of its good heat resistance.Its excellent mechanical properties are inseparable from the regulation of the structure by researchers.The method of material structure simulation has become more and more perfect.This study employs numerical simulation to investigate the microstructure evolution of Al-Cu-Mg-Ag alloys during solidification with the aim of controlling its structure.The size distribution of Ti-containing particles in an Al-Ti-B master alloy was characterized via microstructure observation,serving as a basis for optimizing the nucleation density parameters for particles of varying radii in the phase field model.The addition of refiner inhibited the growth of dendrites and no longer produced coarse dendrites.With the increase of refiner,the grains gradually tended to form cellular morphology.The refined grains were about 100μm in size.Experimental validation of the simulated as-cast grain morphology was conducted.The samples were observed by metallographic microscope and scanning electron microscope.The addition of refiner had a significant effect on the refinement of the alloy,and the average grain size after refinement was also about 100μm.At the same time,the XRD phase identification of the alloy was carried out.The observation of the microstructure morphology under the scanning electron microscope showed that the precipitated phase was mainly concentrated on the grain boundary.The Al_(2)Cu accounted for about 5%,and the matrix phase FCC accounted for about 95%,which also corresponded well with the simulation results.
基金supported by the Guangxi Natural Science Fund for Distinguished Young Scholars(2024GXNSFFA010008)Shenzhen Science and Technology Program(JCYJ20230807112503008).
文摘Nitric oxide(NO),which generally originates from vehicle exhaust and industrial flue gases,is one of the most serious air pollutants.In this case,the electrochemical NO reduction reaction(NORR)not only removes the atmospheric pollutant NO but also produces valuable ammonia(NH_(3)).Hence,through the synthesis and modification of Fe_(3)C nanocrystal cata-lysts,the as-obtained optimal sample of Fe_(3)C/C-900 was adopted as the NORR catalyst at ambient conditions.As a result,the Fe_(3)C/C-900 catalyst showed an NH_(3)Faraday efficiency of 76.5%and an NH_(3)yield rate of 177.5μmol·h^(-1)·cm^(-2)at the working potentials of-0.8 and-1.2 V versus reversible hydrogen electrode(vs.RHE),respectively.And it delivered a stable NORR activity during the electrolysis.Moreover,we attribute the high NORR properties of Fe_(3)C/C-900 to two aspects:one is the enhanced intrinsic activity of Fe_(3)C nanocrystals,including the lowering of the energy barrier of rate-limiting step(*NOH→*N)and the inhibition of hydrogen evolution;on the other hand,the favorable dispersion of active components,the effective adsorption of gaseous NO,and the release of liquid NH_(3)products facilitated by the porous carbon substrate.
