The recovery of nickel from laterite ore with sulphuric acid under the effect of microwave irradiation was studied.The experimental results indicated that the extraction rate of nickel was influenced by reaction time,...The recovery of nickel from laterite ore with sulphuric acid under the effect of microwave irradiation was studied.The experimental results indicated that the extraction rate of nickel was influenced by reaction time,sulphuric acid concentration,and temperature,especially by microwave power.The results obtained from the experiments of orthogonal arrays showed that the optimum conditions of sulphuric acid concentration,reaction time,microwave power,and temperature were 25 vol.%,1.5 h,600 W,and 90°C,respectively.Under the optimal conditions,the nickel recovery could reach approximately 90.8%,which was higher than that obtained by conventional water bath heating.Kinetic experiments showed that the leaching of nickel in a sulphuric acid medium was controlled by chemical reaction occurring on the surface of laterite ore.The apparent activation energy was 38.9 kJ/mol.Microwave heating technology is efficient,clean,and easy to control and facilitate continuous processing of materials.展开更多
With the rapid development of nuclear technology,nuclear protection has received extensive attention.As an important strategic resource,rare earth plays an important role in the field of nuclear shielding materials.In...With the rapid development of nuclear technology,nuclear protection has received extensive attention.As an important strategic resource,rare earth plays an important role in the field of nuclear shielding materials.In this review,the shielding principles of rare earth materials are first introduced.According to the type of matrix,the characteristics and current research status of metal-based,inorganic nonmetallic-based and polymer-based rare earth shielding materials are reviewed.Meanwhile,the future development trend of rare earth shielding materials is discussed.展开更多
A severe accident in a marine nuclear reactor leads to radionuclide leakage,which causes hidden dangers to workers and has adverse effects of environmental pollution.It is necessary to propose a novel approach to radi...A severe accident in a marine nuclear reactor leads to radionuclide leakage,which causes hidden dangers to workers and has adverse effects of environmental pollution.It is necessary to propose a novel approach to radionuclide diffusion in a confined environment after a severe accident in a marine nuclear reactor.Therefore,this study proposes a new method for the severe accident analysis program MELCOR coupled with computational fluid dynamics scSTREAM to study radioactive diffusion in severe accidents.The radionuclide release fraction and temperature calculated by MELCOR were combined with the scSTREAM calculations to study the radionuclide diffusion behavior and the phenomenon of radionuclide diffusion in different space environments of the reactor under the conditions of varying wind velocities of the ventilation system and diffusion speed.The results show that the wind velocity of the ventilation system is very small or zero,and the turbulent diffusion of radionuclides is not obvious and diffuses slowly in the form of condensation sedimentation and gravity settlement.When the wind speed of the ventilation system increases,the flow of radionuclides meets the wall and forms eddy currents,affecting the time variation of radionuclides diffusing into chamber 2.The wind velocity of the ventilation system and the diffusion speed has opposite effects on the time variation trend of radionuclide diffusion into the four chambers.展开更多
Carbon dioxide(CO_(2)) emissions from inland waters to the atmosphere are a pivotal component of the global carbon budget. Anthropogenic land use can influence riverine CO_(2) emissions, but empirical data exploring c...Carbon dioxide(CO_(2)) emissions from inland waters to the atmosphere are a pivotal component of the global carbon budget. Anthropogenic land use can influence riverine CO_(2) emissions, but empirical data exploring cause-effect relationships remain limited. Here, we investigated CO_(2) partial pressures(pCO_(2)) and degassing in a monsoonal river(Yue River)within the Han River draining to the Yangtze in China. Almost 90% of river samples were supersaturated in CO_(2) with a mean ± standard deviation of 1474 ± 1614 μatm, leading to emissions of 557-971 mmol/m^(2)/day from river water to the atmosphere. Annual CO_(2) emissions were 1.6-2.8 times greater than the longitudinal exports of riverine dissolved inorganic and organic carbon. pCO_(2) was positively correlated to anthropogenic land use(urban and farmland), and negatively correlated to forest cover. p CO_(2) also had significant and positive relationships with total dissolved nitrogen and total dissolved phosphorus. Stepwise multiple regression models were developed to predict p CO_(2) . Farmland and urban land released nutrients and organic matter to the river system, driving riverine p CO_(2) enrichment due to enhanced respiration in these heterotrophic rivers. Overall, we show the crucial role of land use driving riverine pCO_(2) , which should be considered in future large-scale estimates of CO_(2) emissions from streams. Land use change can thus modify the carbon balance of urban-river systems by enhancing river emissions, and reforestation helps carbon neutral in rivers.展开更多
The speciation and atomic structures of corrosion products in Ni-based alloys could provide basic information for understanding the Te corrosion mechanism.In this paper,two-dimensional synchrotron-radiation-induced gr...The speciation and atomic structures of corrosion products in Ni-based alloys could provide basic information for understanding the Te corrosion mechanism.In this paper,two-dimensional synchrotron-radiation-induced grazing incidence X-ray diffraction was used to characterize the corrosion products of a Ni–18%Cr binary alloy at temperatures from 600 to 1000℃.The results showed that a film of CrTe is preferentially formed when Te reacts with the Ni-based alloy at low temperatures(below 900℃),while CrTe and Ni3Te2 are formed at 900℃.Moreover,at a temperature of 1000℃,a solid solution is formed without any changes in the Ni–Cr substrate lattice parameters.Furthermore,X-ray absorption fine structure and wavelet transform analyses were used to investigate the atomic local structure of Te.The investigation indicated that Te atoms diffuse into the Ni–Cr substrate to form a substitutional Ni–Cr–Te solid solution at 1000℃.Notably,based on a discussion of the thermodynamics of the chemical reaction process,CrTe is considered to be the most stable and prevalent corrosion product due to its comparatively lower Gibbs free energy of formation.These results demonstrate that the Ni–18%Cr alloy is capable of resisting the diffusion of Te atoms.展开更多
The effect of hydrogen and helium interaction,especially H-He ratio,on the irradiation behavior of nuclear materials has not yet been resolved.However,this is an important basis for evaluating the irradiation properti...The effect of hydrogen and helium interaction,especially H-He ratio,on the irradiation behavior of nuclear materials has not yet been resolved.However,this is an important basis for evaluating the irradiation properties of nuclear materials and developing high irradiation resistant materials.Here,30 keV H_(2)^(+)and He^(+)dual beams with four H-He ratios of 0:10,3:10,15:10,and 30:10 were used to irradiate the newly developed Fe9Cr1.5W0.4Si F/M steel in TEM to in-situ study the interaction and ratio effect of hydrogen and helium.The addition of H atoms significantly promoted the nucleation of dislocation loops and bubbles.In the early stage of irradiation,the average size and density of dislocation loops increased with the increase of H-He ratio.Meanwhile,the larger the H-He ratio,the easier it was to form a complex dislocation network.Furthermore,the final saturation size of bubbles increased with the increase of H-He ratio.It was first found that the swelling was affected by H concentrations,with high H concentrations slowing down the increase in swelling.For a certain irradiation dose,a specific H-He ratio would lead to a swelling peak of Fe9Cr1.5W0.4Si F/M steel.The super-sized bubbles at grain boundaries(GBs)were found after H addition,resulting in a bigger swelling of GBs than the matrix.Both the swelling of the GBs and the matrix show a dependence on the H-He ratio.The current work is of great significance for understanding the interaction between hydrogen and helium in nuclear materials.展开更多
A novel and readily available binaphthyl-based fluorescent probe(S)-1 was designed and synthesized.(S)-1 can be used to not only chemoselectively discriminate 3 basic amino acids out of common amino acids,but also ena...A novel and readily available binaphthyl-based fluorescent probe(S)-1 was designed and synthesized.(S)-1 can be used to not only chemoselectively discriminate 3 basic amino acids out of common amino acids,but also enantioselectively recognize histidine.Encouragingly,enantioselective imaging of histidine in cells was achieved for the first time by the probe(S)-1.These performances endowed it potential application in the chiral analysis of basic amino acids in asymmetric synthesis and cell imaging for diagnosis of diseases caused by racemization of histidine.Nuclear magnetic resonance(NMR)and mass spectrometry investigations suggested that different reaction extent of(S)-1 with L/D-histidine and different product structures generated the observed enantioselective fluorescent response.The molecular structures and thermodynamic stability of the complexes,formed from(S)-1+Zn2+and enantiomers of histidine,were calculated by Gaussian 16 based on density functional theory(DFT)to validate the above action mechanism.展开更多
The zirconium(Zr)alloy fuel cladding is one of the key structural components of a nuclear reactor and the first and most important line of defense for accommodating fission products.During the operation of nuclear rea...The zirconium(Zr)alloy fuel cladding is one of the key structural components of a nuclear reactor and the first and most important line of defense for accommodating fission products.During the operation of nuclear reactors,Zr alloy fuel cladding is subjected to extreme harsh environments,such as high temperature,high pressure and high flow rate for a long period of time.The wear and corrosion resistance of Zr alloys is important for the safe operation of nuclear reactors.Surface modification can effectively improve the corrosion and wear resistance of fuel cladding.Compared with coating technology,nitriding technology does not have problems for bonding between the coating and the substrate.Current research on surface nitriding of Zr alloys mainly focuses on plasma nitriding and ion implantation techniques.Research on laser nitriding of Zr alloy surfaces and their fretting wear characteristics is scarce.In this study,the surface of Zr alloy was treated with laser nitriding at different laser energies.The microstructure of Zr alloy treated with different laser energies and its fretting wear performance were studied.The results showed that after nitriding with different laser energies,the surface of the Zr alloy showed a typical molten state after melting,vaporizing and cooling under the thermal effect of the laser,and this state was more obvious with the increase of the laser energy.At the same time,doping of N atoms and formation of the ZrN phase led to different cooling rates in the molten zone that produced large tensile stresses after cooling.This led to cracks on the surface of Zr alloys after laser nitriding at different energies,and the crack density increased with increasing laser energy.This also led to an increase in the surface roughness of the Zr alloy with increasing laser energy after laser nitriding treatment.Due to the presence of water in the industrial nitrogen,nitrides were generated on the surface of the sample along with some oxides.When the laser energy was 100 mJ,there was no ZrN generation,a展开更多
Herein,we employ the threshold energy neutron analysis(TENA)technique to introduce the world's first active interrogation system to detect special nuclear materials(SNMs),including U-235 and Pu-239.The system util...Herein,we employ the threshold energy neutron analysis(TENA)technique to introduce the world's first active interrogation system to detect special nuclear materials(SNMs),including U-235 and Pu-239.The system utilizes a DD neutron generator based on inertial electrostatic confinement(IEC)to interrogate suspicious objects.To detect secondary neutrons produced during fission reactions induced in SNMs,a tensioned metastable fluid detector(TMFD)is employed.The current status of the system's development is reported in this paper,accompanied by the results from experiments conducted to detect 10 g of highly enriched uranium(HEU).Notably,the experimental findings demonstrate a distinct difference in the count rates of measurements with and without HEU.This difference in count rates surpasses two times the standard deviation,indicating a confidence level of more than 96% for identifying the presence of HEU.The paper presents and extensively discusses the proof-of-principle experimental results,along with the system's planned trajectory.展开更多
In pressurized water reactor(PWR),fretting wear is one of the main causes of fuel assembly failure.Moreover,the operation condition of cladding is complex and harsh.A unique fretting damage test equipment was develope...In pressurized water reactor(PWR),fretting wear is one of the main causes of fuel assembly failure.Moreover,the operation condition of cladding is complex and harsh.A unique fretting damage test equipment was developed and tested to simulate the fretting damage evolution process of cladding in the PWR environment.It can simulate the fretting wear experiment of PWR under different temperatures(maximum temperature is 350℃),displacement amplitude,vibration frequency,and normal force.The fretting wear behavior of Zr-4 alloy under different temperature environments was tested.In addition,the evolution of wear scar morphology,profile,and wear volume was studied using an optical microscope(OM),scanning electron microscopy(SEM),and a 3D white light interferometer.Results show that higher water temperature evidently decreased the cladding wear volume,the wear mechanism of Zr-4 cladding changed from abrasive wear to adhesive wear and the formation of an oxide layer on the wear scar reduced the wear volume and maximum wear depth.展开更多
Spinel cobalt oxide(Co_(3)O_(4)),consisting of tetrahedral Co^(2+)(CoTd)and octahedral Co^(3+)(CoOh),is considered as promising earth-abundant electrocatalyst for chlorine evolution reaction(CER).Identifying the catal...Spinel cobalt oxide(Co_(3)O_(4)),consisting of tetrahedral Co^(2+)(CoTd)and octahedral Co^(3+)(CoOh),is considered as promising earth-abundant electrocatalyst for chlorine evolution reaction(CER).Identifying the catalytic contribution of geometric Co site in the electrocatalytic CER plays a pivotal role to precisely modulate electronic configuration of active Co sites to boost CER.Herein,combining density functional theory calculations and experiment results assisted with operando analysis,we found that the Co_(Oh) site acts as the main active site for CER in spinel Co_(3)O_(4),which shows better Cl^(-)adsorption and more moderate intermediate adsorption toward CER than CoTd site,and does not undergo redox transition under CER condition at applied potentials.Guided by above findings,the oxygen vacancies were further introduced into the Co_(3)O_(4) to precisely manipulate the electronic configuration of Co_(Oh) to boost Cl^(-)adsorption and optimize the reaction path of CER and thus to enhance the intrinsic CER activity significantly.Our work figures out the importance of geometric configuration dependent CER activity,shedding light on the rational design of advanced electrocatalysts from geometric configuration optimization at the atomic level.展开更多
Catalytic fixed-bed is an efficient and facile system for scalable organic synthesis due to its continuous and fast flow operation process.As a key unit in the fixed-bed system,catalytically active packing materials a...Catalytic fixed-bed is an efficient and facile system for scalable organic synthesis due to its continuous and fast flow operation process.As a key unit in the fixed-bed system,catalytically active packing materials are required to possess some properties,such as high activity,excellent stability,and porous packing structure.Herein,we prepare a fibrous fixed-bed catalyst by anchoring Pd nanoparticles on N-doped graphene fiber(NHG)(Pd/NGF).Due to the porous and loose packing structure,the resultant Pd/NGF catalyst can be easily filled into the continuous-flow reactor to construct a fixed-bed system with low flow resistance.The corresponding catalytic fixed-bed system exhibits a favourable flow rate(8 mL/min)and excellent durability toward reduction reactions of N-containing unsaturated compounds to produce aromatic amines.This work provides a new design concept of fibrous fixed-bed catalysts with dual-active components(i.e.,graphene-derived active materials and metal nanoparticles)and catalytic organic synthesis in a continuous-flow process.展开更多
To ensure agreement between theoretical calculations and experimental data,parameters to selected nuclear physics models are perturbed and fine-tuned in nuclear data evaluations.This approach assumes that the chosen s...To ensure agreement between theoretical calculations and experimental data,parameters to selected nuclear physics models are perturbed and fine-tuned in nuclear data evaluations.This approach assumes that the chosen set of models accurately represents the‘true’distribution of considered observables.Furthermore,the models are chosen globally,indicating their applicability across the entire energy range of interest.However,this approach overlooks uncertainties inherent in the models themselves.In this work,we propose that instead of selecting globally a winning model set and proceeding with it as if it was the‘true’model set,we,instead,take a weighted average over multiple models within a Bayesian model averaging(BMA)framework,each weighted by its posterior probability.The method involves executing a set of TALYS calculations by randomly varying multiple nuclear physics models and their parameters to yield a vector of calculated observables.Next,computed likelihood function values at each incident energy point were then combined with the prior distributions to obtain updated posterior distributions for selected cross sections and the elastic angular distributions.As the cross sections and elastic angular distributions were updated locally on a per-energy-point basis,the approach typically results in discontinuities or“kinks”in the cross section curves,and these were addressed using spline interpolation.The proposed BMA method was applied to the evaluation of proton-induced reactions on ^(58)Ni between 1 and 100 MeV.The results demonstrated a favorable comparison with experimental data as well as with the TENDL-2023 evaluation.展开更多
Deformation characteristics and range of optimized hot working parameters of a 6.5 tons GH3535 superalloy ingot with an average columnar grain size of over 1 mm in diameter were investigated. Axial compression experim...Deformation characteristics and range of optimized hot working parameters of a 6.5 tons GH3535 superalloy ingot with an average columnar grain size of over 1 mm in diameter were investigated. Axial compression experiments were performed in temperature range of 900-1240 ℃ and strain rate range of 0.001-30 s;at a total strain of 0.8. The hot deformation activation energy of the experimental GH3535 alloy is calculated to be 483.22 kJ/mol. Furthermore, the deformation constitutive equation is established by the peak stresses obtained from the stress-strain curves under various conditions. The hot working window of the alloy ingot at a strain of 0.8 can be preliminarily discussed based on the deformed microstructures and processing maps. The optimized hot working window was thus determined at the strain of 0.95 for 6.5 tons GH3535 alloy ingot by the supplementary compression tests. A large-size GH3535 superalloy ring with a dimension of 03010 mm x 410 mm was ultimately manufactured.展开更多
The drift-flux model has a practical importance in two-phase flow analysis.In this study,a finite volume solution is developed for a transient four-equation drift-flux model through the staggered mesh,leading to the d...The drift-flux model has a practical importance in two-phase flow analysis.In this study,a finite volume solution is developed for a transient four-equation drift-flux model through the staggered mesh,leading to the development of a fully implicit discretization method.The main advantage of the fully implicit method is its unconditional stability.Newton's scheme is a popular method of choice for the solution of a nonlinear system of equations arising from fully implicit discretization of field equations.However,the lack of convergence robustness and the construction of Jacobian matrix have created several difficulties for the researchers.In this paper,a fully implicit model is developed based on the SIMPLE algorithm for two-phase flow simulations.The drawbacks of Newton's method are avoided in the developed model.Different limiter functions are considered,and the stabilized method is developed under steady and transient conditions.The results obtained by the numerical modeling are in good agreement with the experimental data.As expected,the results prove that the developed model is not restricted by any stability limit.展开更多
Metal-based catalysis,including homogeneous and heterogeneous catalysis,plays a significant role in the modern chemical industry.Heterogeneous catalysis is widely used due to the high efficiency,easy catalyst separati...Metal-based catalysis,including homogeneous and heterogeneous catalysis,plays a significant role in the modern chemical industry.Heterogeneous catalysis is widely used due to the high efficiency,easy catalyst separation and recycling.However,the metal-utilization efficiency for conventional heterogeneous catalysts needs further improvement compared to homogeneous catalyst.To tackle this,the pursing of heterogenizing homogeneous catalysts has always been attractive but challenging.As a recently emerging class of catalytic material,single-atom catalysts(SACs)are expected to bridge homogeneous and heterogeneous catalytic process in organic reactions and have arguably become the most active new frontier in catalysis field.In this review,a brief introduction and development history of single-atom catalysis and SACs involved organic reactions are documented.In addition,recent advances in SACs and their practical applications in organic reactions such as oxidation,reduction,addition,coupling reaction,and other organic reactions are thoroughly reviewed.To understand structure-property relationships of single-atom catalysis in organic reactions,active sites or coordination structure,metal atom-utilization efficiency(e.g.,turnover frequency,TOF calculated based on active metal)and catalytic performance(e.g.,conversion and selectivity)of SACs are comprehensively summarized.Furthermore,the application limitations,development trends,future challenges and perspective of SAC for organic reaction are discussed.展开更多
Lanthanum is one of the rare earth metals which due to specific chemio-physical properties,has wide applications in different industries.In this research,the ability of the synthesized metal-organic framework(MOF),[Zn...Lanthanum is one of the rare earth metals which due to specific chemio-physical properties,has wide applications in different industries.In this research,the ability of the synthesized metal-organic framework(MOF),[Zn(bim)_(2)(bdc)]_(n)(ZBB) for the removal of lanthanum ions from the aqueous stream was investigated in the batch and column processes.The synthesized MOF was characterized by using scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),Fourier transform infrared spectroscopy(FTIR) and thermogravimetric analysis(TGA).The effect of pH on lanthanum ions adsorption was evaluated in the range from 1 to 7.Moreover,isothermal,kinetic,and thermodynamic parameters for adsorption of La(Ⅲ) ions onto the synthesized MOF were evaluated.The adsorption capacity of lanthanum ions onto the synthesized MOF was calculated to be about 130 mg/g.Thermodynamic studies demonstrate the endothermic and chemical nature of lanthanum adsorption,while kinetic studies suggest the pseudo-first-order of reaction.In column mode,the effect of solution flow rate passing through the fixed-bed was studied.Experimental data confirm that increasing the bed flow rate causes a decrease in the adsorption capacity of lanthanum ions on the synthesized MOF.展开更多
As a promising candidate material for the accident tolerant fuel cladding in light water reactors,the Nb-containing FeCrAl alloy has shown outstanding out-of-pile service performance due to the Laves phase precipitati...As a promising candidate material for the accident tolerant fuel cladding in light water reactors,the Nb-containing FeCrAl alloy has shown outstanding out-of-pile service performance due to the Laves phase precipitation.In this work,the radiation response in FeCrAl alloys with gradient Nb content under heavy ion radiation has been investigated.The focus is on the effect of the Laves phase on irradiation-induced defects and hardening.We found that the phase boundary between the matrix and Laves phase can play a critical role in capturing radiation defects,as verified by in-situ heavy-ion radiation experiments and molecular dynamic simulations.Additionally,the evolution of Laves phase under radiation is analyzed.Radiation-induced amorphization and segregations observed at high radiation doses will deepen the fundamental understanding of the stability of Laves phases in the radiation environment.展开更多
Characteristics of thermal-hydraulic interaction of LBE （45w%Pb-55w%Bi） and lead with subcooled water in pool water were investigated experimentally. Two kinds of interaction zones （deformation and fragmentation） ...Characteristics of thermal-hydraulic interaction of LBE （45w%Pb-55w%Bi） and lead with subcooled water in pool water were investigated experimentally. Two kinds of interaction zones （deformation and fragmentation） and three kinds of interaction zones （solidification, deformation and fragmentation） were observed during LBE droplet/water interaction and lead droplet/water interaction, respectively. The fragmentation zone （FZ） could be identified exactly by two border lines： spontaneous nucleation temperature and minimum film boiling temperature. Within fragmentation zone, 10% to 35% tiny debris （diameter 〈 1 mm） of LBE and 5 to 8 kPa peak pressure generated with increasing the LBE temperature and no effect with increasing the subcooling of water. Only 2%-4% tiny debris （diameter 〈 1 mm） of lead and 2 kPa peak pressure generated regardless of lead and water temperature.展开更多
文摘The recovery of nickel from laterite ore with sulphuric acid under the effect of microwave irradiation was studied.The experimental results indicated that the extraction rate of nickel was influenced by reaction time,sulphuric acid concentration,and temperature,especially by microwave power.The results obtained from the experiments of orthogonal arrays showed that the optimum conditions of sulphuric acid concentration,reaction time,microwave power,and temperature were 25 vol.%,1.5 h,600 W,and 90°C,respectively.Under the optimal conditions,the nickel recovery could reach approximately 90.8%,which was higher than that obtained by conventional water bath heating.Kinetic experiments showed that the leaching of nickel in a sulphuric acid medium was controlled by chemical reaction occurring on the surface of laterite ore.The apparent activation energy was 38.9 kJ/mol.Microwave heating technology is efficient,clean,and easy to control and facilitate continuous processing of materials.
基金Project supported by the National Defense Science and Technology Foundation of State Key Laboratory (6142A06180102)。
文摘With the rapid development of nuclear technology,nuclear protection has received extensive attention.As an important strategic resource,rare earth plays an important role in the field of nuclear shielding materials.In this review,the shielding principles of rare earth materials are first introduced.According to the type of matrix,the characteristics and current research status of metal-based,inorganic nonmetallic-based and polymer-based rare earth shielding materials are reviewed.Meanwhile,the future development trend of rare earth shielding materials is discussed.
基金supported by the Postgraduate Scientific Research Innovation Project of Hunan Province (No. CX20210922)
文摘A severe accident in a marine nuclear reactor leads to radionuclide leakage,which causes hidden dangers to workers and has adverse effects of environmental pollution.It is necessary to propose a novel approach to radionuclide diffusion in a confined environment after a severe accident in a marine nuclear reactor.Therefore,this study proposes a new method for the severe accident analysis program MELCOR coupled with computational fluid dynamics scSTREAM to study radioactive diffusion in severe accidents.The radionuclide release fraction and temperature calculated by MELCOR were combined with the scSTREAM calculations to study the radionuclide diffusion behavior and the phenomenon of radionuclide diffusion in different space environments of the reactor under the conditions of varying wind velocities of the ventilation system and diffusion speed.The results show that the wind velocity of the ventilation system is very small or zero,and the turbulent diffusion of radionuclides is not obvious and diffuses slowly in the form of condensation sedimentation and gravity settlement.When the wind speed of the ventilation system increases,the flow of radionuclides meets the wall and forms eddy currents,affecting the time variation of radionuclides diffusing into chamber 2.The wind velocity of the ventilation system and the diffusion speed has opposite effects on the time variation trend of radionuclide diffusion into the four chambers.
基金supported by the National Natural Science Foundation of China (No. 31670473)the Key Program of the Chinese Academy of Sciences (No. ZDRW-ZS-2016-7-2)the Youth Innovation Promotion Association of CAS (No. 2020378)。
文摘Carbon dioxide(CO_(2)) emissions from inland waters to the atmosphere are a pivotal component of the global carbon budget. Anthropogenic land use can influence riverine CO_(2) emissions, but empirical data exploring cause-effect relationships remain limited. Here, we investigated CO_(2) partial pressures(pCO_(2)) and degassing in a monsoonal river(Yue River)within the Han River draining to the Yangtze in China. Almost 90% of river samples were supersaturated in CO_(2) with a mean ± standard deviation of 1474 ± 1614 μatm, leading to emissions of 557-971 mmol/m^(2)/day from river water to the atmosphere. Annual CO_(2) emissions were 1.6-2.8 times greater than the longitudinal exports of riverine dissolved inorganic and organic carbon. pCO_(2) was positively correlated to anthropogenic land use(urban and farmland), and negatively correlated to forest cover. p CO_(2) also had significant and positive relationships with total dissolved nitrogen and total dissolved phosphorus. Stepwise multiple regression models were developed to predict p CO_(2) . Farmland and urban land released nutrients and organic matter to the river system, driving riverine p CO_(2) enrichment due to enhanced respiration in these heterotrophic rivers. Overall, we show the crucial role of land use driving riverine pCO_(2) , which should be considered in future large-scale estimates of CO_(2) emissions from streams. Land use change can thus modify the carbon balance of urban-river systems by enhancing river emissions, and reforestation helps carbon neutral in rivers.
基金supported by the National Key Research and Development Program of China(No.2016YFB0700404)National Natural Science Foundation of China(No.U1732267)+2 种基金National Natural Science Foundation of China(Nos.51671122 and 51671154)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA02004210)Talent Development Fund of Shanghai(No.201650)
文摘The speciation and atomic structures of corrosion products in Ni-based alloys could provide basic information for understanding the Te corrosion mechanism.In this paper,two-dimensional synchrotron-radiation-induced grazing incidence X-ray diffraction was used to characterize the corrosion products of a Ni–18%Cr binary alloy at temperatures from 600 to 1000℃.The results showed that a film of CrTe is preferentially formed when Te reacts with the Ni-based alloy at low temperatures(below 900℃),while CrTe and Ni3Te2 are formed at 900℃.Moreover,at a temperature of 1000℃,a solid solution is formed without any changes in the Ni–Cr substrate lattice parameters.Furthermore,X-ray absorption fine structure and wavelet transform analyses were used to investigate the atomic local structure of Te.The investigation indicated that Te atoms diffuse into the Ni–Cr substrate to form a substitutional Ni–Cr–Te solid solution at 1000℃.Notably,based on a discussion of the thermodynamics of the chemical reaction process,CrTe is considered to be the most stable and prevalent corrosion product due to its comparatively lower Gibbs free energy of formation.These results demonstrate that the Ni–18%Cr alloy is capable of resisting the diffusion of Te atoms.
基金financially supported by the National Natural Science Foundation of China(Nos.U1967211 and 11975191)the National Science Fund for Distinguished Young Scholars of China(No.12225506).
文摘The effect of hydrogen and helium interaction,especially H-He ratio,on the irradiation behavior of nuclear materials has not yet been resolved.However,this is an important basis for evaluating the irradiation properties of nuclear materials and developing high irradiation resistant materials.Here,30 keV H_(2)^(+)and He^(+)dual beams with four H-He ratios of 0:10,3:10,15:10,and 30:10 were used to irradiate the newly developed Fe9Cr1.5W0.4Si F/M steel in TEM to in-situ study the interaction and ratio effect of hydrogen and helium.The addition of H atoms significantly promoted the nucleation of dislocation loops and bubbles.In the early stage of irradiation,the average size and density of dislocation loops increased with the increase of H-He ratio.Meanwhile,the larger the H-He ratio,the easier it was to form a complex dislocation network.Furthermore,the final saturation size of bubbles increased with the increase of H-He ratio.It was first found that the swelling was affected by H concentrations,with high H concentrations slowing down the increase in swelling.For a certain irradiation dose,a specific H-He ratio would lead to a swelling peak of Fe9Cr1.5W0.4Si F/M steel.The super-sized bubbles at grain boundaries(GBs)were found after H addition,resulting in a bigger swelling of GBs than the matrix.Both the swelling of the GBs and the matrix show a dependence on the H-He ratio.The current work is of great significance for understanding the interaction between hydrogen and helium in nuclear materials.
基金financial support from the National Natural Science Foundation of China(Nos.22074114,22377097,21877087)Natural Science Foundation of Hubei Province of China(Nos.2020CFB623,2021CFB556)+2 种基金Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education(No.LCX202305)Wuhan Institute of Technology Graduate Education and Teaching Reform Research Project(Nos.2022JYXM09,2021JYXM07)Wuhan Institute of Technology Graduate Innovation Fund(No.CX2022450)are greatly appreciated。
文摘A novel and readily available binaphthyl-based fluorescent probe(S)-1 was designed and synthesized.(S)-1 can be used to not only chemoselectively discriminate 3 basic amino acids out of common amino acids,but also enantioselectively recognize histidine.Encouragingly,enantioselective imaging of histidine in cells was achieved for the first time by the probe(S)-1.These performances endowed it potential application in the chiral analysis of basic amino acids in asymmetric synthesis and cell imaging for diagnosis of diseases caused by racemization of histidine.Nuclear magnetic resonance(NMR)and mass spectrometry investigations suggested that different reaction extent of(S)-1 with L/D-histidine and different product structures generated the observed enantioselective fluorescent response.The molecular structures and thermodynamic stability of the complexes,formed from(S)-1+Zn2+and enantiomers of histidine,were calculated by Gaussian 16 based on density functional theory(DFT)to validate the above action mechanism.
文摘The zirconium(Zr)alloy fuel cladding is one of the key structural components of a nuclear reactor and the first and most important line of defense for accommodating fission products.During the operation of nuclear reactors,Zr alloy fuel cladding is subjected to extreme harsh environments,such as high temperature,high pressure and high flow rate for a long period of time.The wear and corrosion resistance of Zr alloys is important for the safe operation of nuclear reactors.Surface modification can effectively improve the corrosion and wear resistance of fuel cladding.Compared with coating technology,nitriding technology does not have problems for bonding between the coating and the substrate.Current research on surface nitriding of Zr alloys mainly focuses on plasma nitriding and ion implantation techniques.Research on laser nitriding of Zr alloy surfaces and their fretting wear characteristics is scarce.In this study,the surface of Zr alloy was treated with laser nitriding at different laser energies.The microstructure of Zr alloy treated with different laser energies and its fretting wear performance were studied.The results showed that after nitriding with different laser energies,the surface of the Zr alloy showed a typical molten state after melting,vaporizing and cooling under the thermal effect of the laser,and this state was more obvious with the increase of the laser energy.At the same time,doping of N atoms and formation of the ZrN phase led to different cooling rates in the molten zone that produced large tensile stresses after cooling.This led to cracks on the surface of Zr alloys after laser nitriding at different energies,and the crack density increased with increasing laser energy.This also led to an increase in the surface roughness of the Zr alloy with increasing laser energy after laser nitriding treatment.Due to the presence of water in the industrial nitrogen,nitrides were generated on the surface of the sample along with some oxides.When the laser energy was 100 mJ,there was no ZrN generation,a
基金supported by Special Coordination Funds for Promoting Science and Technology,sponsored by Japan’s Ministry of Education,Culture,Sports,Science and Technology(MEXT).
文摘Herein,we employ the threshold energy neutron analysis(TENA)technique to introduce the world's first active interrogation system to detect special nuclear materials(SNMs),including U-235 and Pu-239.The system utilizes a DD neutron generator based on inertial electrostatic confinement(IEC)to interrogate suspicious objects.To detect secondary neutrons produced during fission reactions induced in SNMs,a tensioned metastable fluid detector(TMFD)is employed.The current status of the system's development is reported in this paper,accompanied by the results from experiments conducted to detect 10 g of highly enriched uranium(HEU).Notably,the experimental findings demonstrate a distinct difference in the count rates of measurements with and without HEU.This difference in count rates surpasses two times the standard deviation,indicating a confidence level of more than 96% for identifying the presence of HEU.The paper presents and extensively discusses the proof-of-principle experimental results,along with the system's planned trajectory.
基金Supported by National Key R&D Program of China(Grant No.2022YFB3401901)Key Program of National Natural Science Foundation of China(Grant No.U2067221)+2 种基金Sichuan Provincial Science and Technology Planning Project(Grant Nos.2022JDJQ0019 and 2022ZYD0029)Funds for China Postdoctoral Science Foundation(Grant No.2022M713008)Sichuan Provincial Innovative Talent Funding Project for Postdoctoral Fellows(Grant No.BX202225).
文摘In pressurized water reactor(PWR),fretting wear is one of the main causes of fuel assembly failure.Moreover,the operation condition of cladding is complex and harsh.A unique fretting damage test equipment was developed and tested to simulate the fretting damage evolution process of cladding in the PWR environment.It can simulate the fretting wear experiment of PWR under different temperatures(maximum temperature is 350℃),displacement amplitude,vibration frequency,and normal force.The fretting wear behavior of Zr-4 alloy under different temperature environments was tested.In addition,the evolution of wear scar morphology,profile,and wear volume was studied using an optical microscope(OM),scanning electron microscopy(SEM),and a 3D white light interferometer.Results show that higher water temperature evidently decreased the cladding wear volume,the wear mechanism of Zr-4 cladding changed from abrasive wear to adhesive wear and the formation of an oxide layer on the wear scar reduced the wear volume and maximum wear depth.
基金the National Natural Science Foundation of China(U21A20286,22206054 and 21805069)Natural Science Foundation of Hubei(2021CFB094)the Fundamental Research Funds for the Central China Normal University(CCNU)for financial support。
文摘Spinel cobalt oxide(Co_(3)O_(4)),consisting of tetrahedral Co^(2+)(CoTd)and octahedral Co^(3+)(CoOh),is considered as promising earth-abundant electrocatalyst for chlorine evolution reaction(CER).Identifying the catalytic contribution of geometric Co site in the electrocatalytic CER plays a pivotal role to precisely modulate electronic configuration of active Co sites to boost CER.Herein,combining density functional theory calculations and experiment results assisted with operando analysis,we found that the Co_(Oh) site acts as the main active site for CER in spinel Co_(3)O_(4),which shows better Cl^(-)adsorption and more moderate intermediate adsorption toward CER than CoTd site,and does not undergo redox transition under CER condition at applied potentials.Guided by above findings,the oxygen vacancies were further introduced into the Co_(3)O_(4) to precisely manipulate the electronic configuration of Co_(Oh) to boost Cl^(-)adsorption and optimize the reaction path of CER and thus to enhance the intrinsic CER activity significantly.Our work figures out the importance of geometric configuration dependent CER activity,shedding light on the rational design of advanced electrocatalysts from geometric configuration optimization at the atomic level.
基金the Key Research and Development Program of Hubei Province(No.2022BAA026)the Open/Innovation Project of Key Laboratory of Novel Biomass-Based Environmental and Energy Materials in Petroleum and Chemical Industry(No.2022BEEA06)+3 种基金the Open Project of Hubei Key Laboratory of Novel Reactor and Green Chemical Technology(No.NRGC202203)the Open Project of Key Laboratory of Green Chemical Engineering Process of Ministry of Education(No.GCP20220205)the Innovation and Entrepreneurship Training Program Funded by Wuhan Institute of Technology(No.202310490007)the Postgraduate Innovation Foundation from Wuhan Institute of Technology(No.CX2022459).
文摘Catalytic fixed-bed is an efficient and facile system for scalable organic synthesis due to its continuous and fast flow operation process.As a key unit in the fixed-bed system,catalytically active packing materials are required to possess some properties,such as high activity,excellent stability,and porous packing structure.Herein,we prepare a fibrous fixed-bed catalyst by anchoring Pd nanoparticles on N-doped graphene fiber(NHG)(Pd/NGF).Due to the porous and loose packing structure,the resultant Pd/NGF catalyst can be easily filled into the continuous-flow reactor to construct a fixed-bed system with low flow resistance.The corresponding catalytic fixed-bed system exhibits a favourable flow rate(8 mL/min)and excellent durability toward reduction reactions of N-containing unsaturated compounds to produce aromatic amines.This work provides a new design concept of fibrous fixed-bed catalysts with dual-active components(i.e.,graphene-derived active materials and metal nanoparticles)and catalytic organic synthesis in a continuous-flow process.
基金funding from the Paul ScherrerInstitute,Switzerland through the NES/GFA-ABE Cross Project。
文摘To ensure agreement between theoretical calculations and experimental data,parameters to selected nuclear physics models are perturbed and fine-tuned in nuclear data evaluations.This approach assumes that the chosen set of models accurately represents the‘true’distribution of considered observables.Furthermore,the models are chosen globally,indicating their applicability across the entire energy range of interest.However,this approach overlooks uncertainties inherent in the models themselves.In this work,we propose that instead of selecting globally a winning model set and proceeding with it as if it was the‘true’model set,we,instead,take a weighted average over multiple models within a Bayesian model averaging(BMA)framework,each weighted by its posterior probability.The method involves executing a set of TALYS calculations by randomly varying multiple nuclear physics models and their parameters to yield a vector of calculated observables.Next,computed likelihood function values at each incident energy point were then combined with the prior distributions to obtain updated posterior distributions for selected cross sections and the elastic angular distributions.As the cross sections and elastic angular distributions were updated locally on a per-energy-point basis,the approach typically results in discontinuities or“kinks”in the cross section curves,and these were addressed using spline interpolation.The proposed BMA method was applied to the evaluation of proton-induced reactions on ^(58)Ni between 1 and 100 MeV.The results demonstrated a favorable comparison with experimental data as well as with the TENDL-2023 evaluation.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA02004210)
文摘Deformation characteristics and range of optimized hot working parameters of a 6.5 tons GH3535 superalloy ingot with an average columnar grain size of over 1 mm in diameter were investigated. Axial compression experiments were performed in temperature range of 900-1240 ℃ and strain rate range of 0.001-30 s;at a total strain of 0.8. The hot deformation activation energy of the experimental GH3535 alloy is calculated to be 483.22 kJ/mol. Furthermore, the deformation constitutive equation is established by the peak stresses obtained from the stress-strain curves under various conditions. The hot working window of the alloy ingot at a strain of 0.8 can be preliminarily discussed based on the deformed microstructures and processing maps. The optimized hot working window was thus determined at the strain of 0.95 for 6.5 tons GH3535 alloy ingot by the supplementary compression tests. A large-size GH3535 superalloy ring with a dimension of 03010 mm x 410 mm was ultimately manufactured.
文摘The drift-flux model has a practical importance in two-phase flow analysis.In this study,a finite volume solution is developed for a transient four-equation drift-flux model through the staggered mesh,leading to the development of a fully implicit discretization method.The main advantage of the fully implicit method is its unconditional stability.Newton's scheme is a popular method of choice for the solution of a nonlinear system of equations arising from fully implicit discretization of field equations.However,the lack of convergence robustness and the construction of Jacobian matrix have created several difficulties for the researchers.In this paper,a fully implicit model is developed based on the SIMPLE algorithm for two-phase flow simulations.The drawbacks of Newton's method are avoided in the developed model.Different limiter functions are considered,and the stabilized method is developed under steady and transient conditions.The results obtained by the numerical modeling are in good agreement with the experimental data.As expected,the results prove that the developed model is not restricted by any stability limit.
基金financially supported by the Key Research and Development Program of Hubei Province(No.2022BAA026)the Major Project of Hubei Provincial Department of Education(No.D20211502)+1 种基金the Open/Innovation Project of Key Laboratory of Novel Biomass-Based Environmental and Energy Materials in Petroleum and Chemical Industry(No.2022BEEA06)support by the Postgraduate Innovation Foundation from Wuhan Institute of Technology(No.CX2021364)。
文摘Metal-based catalysis,including homogeneous and heterogeneous catalysis,plays a significant role in the modern chemical industry.Heterogeneous catalysis is widely used due to the high efficiency,easy catalyst separation and recycling.However,the metal-utilization efficiency for conventional heterogeneous catalysts needs further improvement compared to homogeneous catalyst.To tackle this,the pursing of heterogenizing homogeneous catalysts has always been attractive but challenging.As a recently emerging class of catalytic material,single-atom catalysts(SACs)are expected to bridge homogeneous and heterogeneous catalytic process in organic reactions and have arguably become the most active new frontier in catalysis field.In this review,a brief introduction and development history of single-atom catalysis and SACs involved organic reactions are documented.In addition,recent advances in SACs and their practical applications in organic reactions such as oxidation,reduction,addition,coupling reaction,and other organic reactions are thoroughly reviewed.To understand structure-property relationships of single-atom catalysis in organic reactions,active sites or coordination structure,metal atom-utilization efficiency(e.g.,turnover frequency,TOF calculated based on active metal)and catalytic performance(e.g.,conversion and selectivity)of SACs are comprehensively summarized.Furthermore,the application limitations,development trends,future challenges and perspective of SAC for organic reaction are discussed.
文摘Lanthanum is one of the rare earth metals which due to specific chemio-physical properties,has wide applications in different industries.In this research,the ability of the synthesized metal-organic framework(MOF),[Zn(bim)_(2)(bdc)]_(n)(ZBB) for the removal of lanthanum ions from the aqueous stream was investigated in the batch and column processes.The synthesized MOF was characterized by using scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),Fourier transform infrared spectroscopy(FTIR) and thermogravimetric analysis(TGA).The effect of pH on lanthanum ions adsorption was evaluated in the range from 1 to 7.Moreover,isothermal,kinetic,and thermodynamic parameters for adsorption of La(Ⅲ) ions onto the synthesized MOF were evaluated.The adsorption capacity of lanthanum ions onto the synthesized MOF was calculated to be about 130 mg/g.Thermodynamic studies demonstrate the endothermic and chemical nature of lanthanum adsorption,while kinetic studies suggest the pseudo-first-order of reaction.In column mode,the effect of solution flow rate passing through the fixed-bed was studied.Experimental data confirm that increasing the bed flow rate causes a decrease in the adsorption capacity of lanthanum ions on the synthesized MOF.
基金This work was financially supported by the National Natural Science Foundation of China(Grants No.U1867215,12025503,and 52122103)Hubei Provincial Natural Science Foundation(Grant No.2019CFA036).
文摘As a promising candidate material for the accident tolerant fuel cladding in light water reactors,the Nb-containing FeCrAl alloy has shown outstanding out-of-pile service performance due to the Laves phase precipitation.In this work,the radiation response in FeCrAl alloys with gradient Nb content under heavy ion radiation has been investigated.The focus is on the effect of the Laves phase on irradiation-induced defects and hardening.We found that the phase boundary between the matrix and Laves phase can play a critical role in capturing radiation defects,as verified by in-situ heavy-ion radiation experiments and molecular dynamic simulations.Additionally,the evolution of Laves phase under radiation is analyzed.Radiation-induced amorphization and segregations observed at high radiation doses will deepen the fundamental understanding of the stability of Laves phases in the radiation environment.
文摘Characteristics of thermal-hydraulic interaction of LBE （45w%Pb-55w%Bi） and lead with subcooled water in pool water were investigated experimentally. Two kinds of interaction zones （deformation and fragmentation） and three kinds of interaction zones （solidification, deformation and fragmentation） were observed during LBE droplet/water interaction and lead droplet/water interaction, respectively. The fragmentation zone （FZ） could be identified exactly by two border lines： spontaneous nucleation temperature and minimum film boiling temperature. Within fragmentation zone, 10% to 35% tiny debris （diameter 〈 1 mm） of LBE and 5 to 8 kPa peak pressure generated with increasing the LBE temperature and no effect with increasing the subcooling of water. Only 2%-4% tiny debris （diameter 〈 1 mm） of lead and 2 kPa peak pressure generated regardless of lead and water temperature.
