This paper proposes a sub-critical nuclear energy system driven by fusion neutron source, FDS, which can be used to transmute long-lived radioactive wastes and to produce fissile nuclear fuel as a way for early applic...This paper proposes a sub-critical nuclear energy system driven by fusion neutron source, FDS, which can be used to transmute long-lived radioactive wastes and to produce fissile nuclear fuel as a way for early application of fusion technology. The necessity and feasibility to develop that system in China are illustrated on the basis of prediction of the demand of energy source in the first half of the 21th century, the status of current fission energy supply and the progress in fusion technology in the world. The characteristics of fusion neutron driver and the potential for transmutation of long-lived nuclear wastes and breeding of fissile nuclear fuel in a blanket are analyzed. A scenario of development steps is proposed.展开更多
This work represents the extraction of oil with high free fatty acid content from spent bleaching earth using sub-critical water technology as a greener production pathway. The extraction efficiencies under different ...This work represents the extraction of oil with high free fatty acid content from spent bleaching earth using sub-critical water technology as a greener production pathway. The extraction efficiencies under different conditions were investigated. The studied parameters include temperatures in the range of 180 to 270°C, the feed to solventfeed-to-solvent (in this case water) ratio (1:1, 1:2, 1:3, 1:4 and 1:5) and extraction times in the range of 5-60 minutes. The results showed that the optimum temperature, feed to solventfeed-to-solvent ratio, and extraction time were 270°C, 1:3, and 20 minutes, respectively. In another experiment, the extracted free fatty acids were converted into mono-, di-, and triglycerides through esterification with glycerol to increase the value added of the extracted products. The kinetics of the extraction process was found to be corresponding to an irreversible consecutive unimolecular-type first order reaction, consisting of the extraction step followed by the decomposition reaction step. Both reaction rates of extraction and decomposition were estimated using the reaction rate equations utilizing the nonlinear regression method. The apparent activation energy was calculated to be 46.1 kJ·mol-1. This result indicates a diffusion controlled reaction. For more exploration and deep understanding of the extraction mechanism, other thermodynamic parameters were also calculated and analyzed including,ΔH#, ΔS#, and ΔG# of the extraction step.展开更多
Membrane fouling is often considered as a hindrance for the application of microfiltration/ultrafiltration(MF/UF) for drinking water production. A novel process of photocatalytic membrane reactor/dynamic membrane(PMR/...Membrane fouling is often considered as a hindrance for the application of microfiltration/ultrafiltration(MF/UF) for drinking water production. A novel process of photocatalytic membrane reactor/dynamic membrane(PMR/DM), operating in a continuous mode under sub-critical flux, was proposed for the mitigation of membrane fouling caused by humic acids(HAs) in water. The mechanism of membrane fouling alleviation with synergistic photocatalytic oxidation and dynamic layer isolating effect was comprehensively investigated from the characterization of foulant evolution responsible for the reversible and irreversible fouling. The results showed that the PMR/DM utilized photocatalytic oxidation to enhance the porosity and hydrophilicity of the fouling layer by converting the high molecular weight(MW) and hydrophobic HA molecules with carboxylic functional groups and aromatic structures into low-MW hydrophilic or transphilic fractions, including tryptophan-like or fulvic-like substances. The fouling layer formed in the PMR/DM by combination of photocatalytic oxidation and DM running at a sub-critical flux of 100 L·h^-1·m^-2, was more hydrophilic and more porous, resulting in the lowest trans-membrane pressure(TMP) growth rates, as compared to the processes of ceramic membrane(CM), DM and PMR/CM.Meanwhile, the dynamic layer prevented the foulants, particularly the high-MW hydrophobic fractions,from contacting the primary membrane, which enabled the membrane permeability to be restored easily.展开更多
Shear-box(i.e.compression-shear) test and newly designed electrically conductive adhesive method were used to measure shear crack sub-critical propagation time and rate of sandstone specimen.Different cubic specimens ...Shear-box(i.e.compression-shear) test and newly designed electrically conductive adhesive method were used to measure shear crack sub-critical propagation time and rate of sandstone specimen.Different cubic specimens with and without holes were tested to study the effect of holes on the shear crack sub-critical propagation.Numerical and experimental results show that three independent variables of hole,the interval distance S,the distance between the center of hole and the crack tip L,and hole radius R,have different contribution to the ratio of stress intensity factor of the specimen with holes to that of the specimen without hole,KⅡ/KⅡ0.Increasing S and decreasing L and R will result in the decrease of KⅡ/KⅡ0 and help crack arrest.The weight relation of the independent variables for KⅡ/KⅡ0 is S>L>R.The specimen DH3 with the largest value of S and the smallest values of L and R has the longest sub-critical crack propagation time and the smallest sub-critical crack propagation rate.Adding two suitable holes symmetrically to the original crack plane in rock specimen is considered to be a potential method for crack arrest of rock.展开更多
In-plane shear crack sub-critical propagation of rock at high temperature was studied by finite element method and shear-box(i.e.compression-shear) test with newly designed electrically conductive adhesive method.Nume...In-plane shear crack sub-critical propagation of rock at high temperature was studied by finite element method and shear-box(i.e.compression-shear) test with newly designed electrically conductive adhesive method.Numerical and experimental results show that the normalized shear(Mode Ⅱ) stress intensity factors,K ⅡT/KT0 is decreased as the temperature increases because high temperature can improve stress distribution at crack tip and reduce the Mode Ⅱ stress intensity factor.Microscopic features of fractured surface are of little pits and secondary micro-cracks in the vicinity(1.5-4.0 mm) of the crack tip.The chevron-shape secondary cracks gradually merge in the length of about 4-5 mm and disappear along the direction of crack propagation.Stable shear crack propagation time is increased with the increasing temperature while the stable shear crack propagation rate is decreased with the increasing temperature,since high temperature can increase the shear(Mode Ⅱ) fracture toughness and prevent the crack growth.It is necessary to ensure the ligament of specimen long enough to measure the maximum unstable crack propagation rate of rock.展开更多
The strata movement induced by sub-critical extraction is a problem not receiving due attention because of its relatively small magnitude of deformation. However, with the increase of mining depth, sub-critical extrac...The strata movement induced by sub-critical extraction is a problem not receiving due attention because of its relatively small magnitude of deformation. However, with the increase of mining depth, sub-critical extraction has become a general phenomenon. This calls for an in-depth investigation into the characteristics of ground movements observed under different extents of sub-critical extraction, so as to determine the appropriate mining technique for use. Following a discussion of the factors influencing the extent of super-critical extraction, the super-critical extraction extent evaluation criteria was presented, the characteristics and laws of the strata and ground movements caused by such an extraction condition were systematically analyzed, and the mechanism of surface subsidence induced by sub-critical extraction was revealed. The result of study may serve as a basis for the development of the strata and ground movement prediction model and the mining techniques appropriate for use at depth beneath surface structures and buildings.展开更多
In reactor physics tests, it is important to monitor sub-criticality continuously during criticality approach. Reactivity measurements by the inverse kinetics method are widely used during the operation of a nuclear r...In reactor physics tests, it is important to monitor sub-criticality continuously during criticality approach. Reactivity measurements by the inverse kinetics method are widely used during the operation of a nuclear reactor. This technique is successfully applied at sufficiently high power level or to a core without an external neutron source where the neutron source term in point reactor kinetics equations may be neglected. For operation at low power levels or in the sub-critical domain, the increase in the fluctuation of the neutron signal may cause difficulties in the evaluation of reactivity and the effect of direct emission from the external neutron source may not be neglected. Therefore, contribution of the neutron source must be taken into account and this implies knowledge of a quantity proportional to the source strength, which calls the source term and then it should be determined. The research work has been conducted to measure reactivity with source term using a dedicated reactivity measurement system by the Least Square Inverse Kinetics Method (LSIKM). Application to a simulator of HANARO research reactor, Korea Atomic Energy Research Institute (KAERI), with known source strength and reactivity worth has showed consistent and satisfactory agreement.展开更多
The co-liquefaction behaviors of cotton seed(CS)and flos populi(FP)were investigated in the sub-critical water/ethanol mixed solvent using the medical stone(MS)based additives.Oil products were characterized using FTI...The co-liquefaction behaviors of cotton seed(CS)and flos populi(FP)were investigated in the sub-critical water/ethanol mixed solvent using the medical stone(MS)based additives.Oil products were characterized using FTIR,GC-MS,1HNMR,and 13CNMR techniques.The test results showed that the synergistic effect of co-liquefaction was obvious when the ratio of cotton seed and flospopuli was 1:1 without additives.The additives,such as 12-phosphotungstic acid(PW12),HZSM-5,PW12/HZSM-5 and modified medical stone(MS),PW12/MS,Ni/MS,Co/MS,Mo/MS and Co-Mo/MS,could increase the bio-oil yield;and the modified MS resulted in higher liquefied oil yield than that achieved by MS.Furthermore,additives such as Ni/MS,Mo/MS,and Co-Mo/MS also could increase the yield of aliphatic hydrocarbons in liquefied oil.The addition of Co-Mo/MS could lead to a highest liquefied oil yield of 28.8%,while the additive of PW12/HZSM-5 could result in a highest total conversion of 81.6%.Results also revealed that additives,such as PW12/MS,PW12,PW12/HZSM-5,Ni/MS,Co/MS,Mo/MS,and Co-Mo/MS,could increase the H2 production and decrease the CO2 production in gas products.展开更多
[Objectives] To study the optimal conditions for extracting procyanidins fromLycium ruthenicum Murr. with sub-critical fluid R134 a( 1,1,1,2-tetrafluoroethane) in 1 L extraction kettle. [Methods]Taking the extraction ...[Objectives] To study the optimal conditions for extracting procyanidins fromLycium ruthenicum Murr. with sub-critical fluid R134 a( 1,1,1,2-tetrafluoroethane) in 1 L extraction kettle. [Methods]Taking the extraction rate of procyanidins as an indicator,the influence of pressure,temperature,and extraction time on extraction rate of procyanidins fromL. Ruthenicum Murr. was studied by single factor experimental methods and orthogonal array design. [Results]The order of factors affecting extraction rate of procyanidins was extraction temperature > extraction pressure > extraction time. The optimum extraction conditions were as follows: the extraction rate of procyanidins fromL. ruthenicum Murr. was the highest with extraction pressure of 1. 2 MPa,extraction temperature of 50℃ and extraction time of 90 min. The content of procyanidins in L. ruthenicum Murr. from different producing areas was determined by vanillin-HCl method under the optimal conditions. [Conclusions] The method has the advantages of easy operation,good selectivity,low extraction temperature and high extraction efficiency,which is suitable for extraction of procyanidins in L. ruthenicum Murr.展开更多
Sub-critical water extraction is a brand-new separation technology. This paper mainly discussed the principle, advantages of sub-critical water extraction, and its applications ranging from the medicinal plants tradit...Sub-critical water extraction is a brand-new separation technology. This paper mainly discussed the principle, advantages of sub-critical water extraction, and its applications ranging from the medicinal plants traditionally used in Europe and Asia to produce pharmaceutical extracts (such as volatile oil, tannins, flavonoids, anthraquinone, lactone, etc.). Meanwhile, the prospect of sub-critical water extraction in plant extractives is also explored. It will be widely used in the field of medical plants, bringing huge economic benefits, environmental benefits and social benefits.展开更多
Deuteron-driven spallation targets have garnered attention recently because they can provide high-energy neutrons to transmute long-lifetime fission products.In this study,the Geant4 toolkit was used to simulate the i...Deuteron-driven spallation targets have garnered attention recently because they can provide high-energy neutrons to transmute long-lifetime fission products.In this study,the Geant4 toolkit was used to simulate the inter-action between a deuteron beam at 500 MeV and a com-posite target composed of alternating lead-bismuth eutectic(LBE)and water.The water was used because it may be employed as a target coolant.The energy spectrum,neu-tron yield,average energy,and total energy of the emitted neutrons were calculated for different thicknesses and thickness ratios between the LBE and water.For a constant target thickness,the neutron yield increases with an increasing thickness ratio of LBE to H 2 O,while the aver-age energy of the emitted neutrons decreases with an increasing in the aforementioned thickness ratio.These two aspects support the use of a pure target,either LBE or water.However,with an increasing LBE-to-H 2 O thickness ratio,the total energy of the emitted neutrons increases and then decreases.This result supports the addition of water into the LBE target.The angular distributions of the emitted neutrons show that the rear of the target is suit-able for loading nuclear waste containing minor actinides and long-lifetime fission products.展开更多
Transformations accompanying shape-instability govern the morphological configuration and distribution of the phases in a microstructure.Owing to the influence of the microstructure on the properties of a material,in ...Transformations accompanying shape-instability govern the morphological configuration and distribution of the phases in a microstructure.Owing to the influence of the microstructure on the properties of a material,in the present work,the stability of three-dimensional rods in a‘representative'polycrystalline system is extensively analysed.A multiphase-field model,which recovers the physical laws and sharpinterface relations,and includes grain boundary diffusion,is adopted to investigate the morphological evolution of the precipitate.Moreover,the efficiency of the numerical approach is ensured by establishing the volume-preserving chemical equilibrium through the incorporation TCFe8(CALPHAD)data and solving phase-field evolution in the Allen-Cahn framework.The morphological evolution of the rod in the representative multiphase system exhibits a unique transformation mechanism which is significantly different from the evolution of an isolated finite-structure.It is realised that,in a polycrystalline arrangement,irrespective of the initial size of the rod,the shape-change begins with the energy-minimising events at the triple junctions.This early transformation renders a characteristic morphology at the longitudinal ends of the structure,which introduces sufficient driving-force through the curvature-difference for the subsequent morphological changes.The continued mass transfer to the terminations,ultimately,breaks-off the rod into separate entities that are entangled in the grain boundary.With increase in the aspect ratio of the rod,it is identified that the source of mass transfer,which turns into the ovulation site,shifts from the centre.This increases the number of fragmentation events and introduces satellite particle.The size of the satellite particle is dictated by a definite ovulation criterion,which is ascertained by examining the transformation of different-sized rods.A comprehensive understanding of the transformation kinetics and mechanism governing the morphological evolution of the rods in a polycrystalline system is rendered in this work.展开更多
Background In an accelerator-driven sub-critical system(ADS),a strong proton beam from a high-power proton accelerator irradiates a spallation target to produce very intense neutrons for driving a reactor.Currently,th...Background In an accelerator-driven sub-critical system(ADS),a strong proton beam from a high-power proton accelerator irradiates a spallation target to produce very intense neutrons for driving a reactor.Currently,the China ADS front-end demo linac(CAFe)facility is being built to provide strong beam with the beam intensity of several mAs.Purpose This paper reports the machine protection system(MPS)of the CAFe facility,which prevents or minimizes the beam-induced damages or the damages from other sources to the machines in the accelerator.Method The MPS of CAFe facility works under the framework of experimental physics and industrial control system(EPICS).The developed machine protection system includes fast protection function and slow interlock function,where the fast function is performed by FPGA controller and the slow function is performed by PLC controller.Results Based on the reports on the status of all relevant subsystems,MPS will either perform an emergency shutdown of the beam or machine or will permit normal operation.When an emergency shutdown of the beam is needed,MPS switches off the ion source or switches on the chopper.In addition to its protective role,MPS will also trace the origin of an emergency shutdown.Conclusions The developed MPS has played an important role during the commissioning and successful operation of the CAFe facility at the end of 2019.展开更多
文摘This paper proposes a sub-critical nuclear energy system driven by fusion neutron source, FDS, which can be used to transmute long-lived radioactive wastes and to produce fissile nuclear fuel as a way for early application of fusion technology. The necessity and feasibility to develop that system in China are illustrated on the basis of prediction of the demand of energy source in the first half of the 21th century, the status of current fission energy supply and the progress in fusion technology in the world. The characteristics of fusion neutron driver and the potential for transmutation of long-lived nuclear wastes and breeding of fissile nuclear fuel in a blanket are analyzed. A scenario of development steps is proposed.
文摘This work represents the extraction of oil with high free fatty acid content from spent bleaching earth using sub-critical water technology as a greener production pathway. The extraction efficiencies under different conditions were investigated. The studied parameters include temperatures in the range of 180 to 270°C, the feed to solventfeed-to-solvent (in this case water) ratio (1:1, 1:2, 1:3, 1:4 and 1:5) and extraction times in the range of 5-60 minutes. The results showed that the optimum temperature, feed to solventfeed-to-solvent ratio, and extraction time were 270°C, 1:3, and 20 minutes, respectively. In another experiment, the extracted free fatty acids were converted into mono-, di-, and triglycerides through esterification with glycerol to increase the value added of the extracted products. The kinetics of the extraction process was found to be corresponding to an irreversible consecutive unimolecular-type first order reaction, consisting of the extraction step followed by the decomposition reaction step. Both reaction rates of extraction and decomposition were estimated using the reaction rate equations utilizing the nonlinear regression method. The apparent activation energy was calculated to be 46.1 kJ·mol-1. This result indicates a diffusion controlled reaction. For more exploration and deep understanding of the extraction mechanism, other thermodynamic parameters were also calculated and analyzed including,ΔH#, ΔS#, and ΔG# of the extraction step.
基金Supported by the National Natural Science Foundation of China(21566013,51562016)Youth Science Foundation of Jiangxi Provincial Department of Education,China(GJJ170970)the Natural Science Foundation of Jiangxi Province(20171BAB206015)
文摘Membrane fouling is often considered as a hindrance for the application of microfiltration/ultrafiltration(MF/UF) for drinking water production. A novel process of photocatalytic membrane reactor/dynamic membrane(PMR/DM), operating in a continuous mode under sub-critical flux, was proposed for the mitigation of membrane fouling caused by humic acids(HAs) in water. The mechanism of membrane fouling alleviation with synergistic photocatalytic oxidation and dynamic layer isolating effect was comprehensively investigated from the characterization of foulant evolution responsible for the reversible and irreversible fouling. The results showed that the PMR/DM utilized photocatalytic oxidation to enhance the porosity and hydrophilicity of the fouling layer by converting the high molecular weight(MW) and hydrophobic HA molecules with carboxylic functional groups and aromatic structures into low-MW hydrophilic or transphilic fractions, including tryptophan-like or fulvic-like substances. The fouling layer formed in the PMR/DM by combination of photocatalytic oxidation and DM running at a sub-critical flux of 100 L·h^-1·m^-2, was more hydrophilic and more porous, resulting in the lowest trans-membrane pressure(TMP) growth rates, as compared to the processes of ceramic membrane(CM), DM and PMR/CM.Meanwhile, the dynamic layer prevented the foulants, particularly the high-MW hydrophobic fractions,from contacting the primary membrane, which enabled the membrane permeability to be restored easily.
基金Project(50374073) supported by the National Natural Science Foundation of ChinaProject(1343-77239) supported by the Graduate Education Innovation Project of Central South University,China
文摘Shear-box(i.e.compression-shear) test and newly designed electrically conductive adhesive method were used to measure shear crack sub-critical propagation time and rate of sandstone specimen.Different cubic specimens with and without holes were tested to study the effect of holes on the shear crack sub-critical propagation.Numerical and experimental results show that three independent variables of hole,the interval distance S,the distance between the center of hole and the crack tip L,and hole radius R,have different contribution to the ratio of stress intensity factor of the specimen with holes to that of the specimen without hole,KⅡ/KⅡ0.Increasing S and decreasing L and R will result in the decrease of KⅡ/KⅡ0 and help crack arrest.The weight relation of the independent variables for KⅡ/KⅡ0 is S>L>R.The specimen DH3 with the largest value of S and the smallest values of L and R has the longest sub-critical crack propagation time and the smallest sub-critical crack propagation rate.Adding two suitable holes symmetrically to the original crack plane in rock specimen is considered to be a potential method for crack arrest of rock.
基金Project(50374073) supported by the National Natural Science Foundation of ChinaProject(1343-77239) supported by the Graduate Education Innovation Project of Central South University,China
文摘In-plane shear crack sub-critical propagation of rock at high temperature was studied by finite element method and shear-box(i.e.compression-shear) test with newly designed electrically conductive adhesive method.Numerical and experimental results show that the normalized shear(Mode Ⅱ) stress intensity factors,K ⅡT/KT0 is decreased as the temperature increases because high temperature can improve stress distribution at crack tip and reduce the Mode Ⅱ stress intensity factor.Microscopic features of fractured surface are of little pits and secondary micro-cracks in the vicinity(1.5-4.0 mm) of the crack tip.The chevron-shape secondary cracks gradually merge in the length of about 4-5 mm and disappear along the direction of crack propagation.Stable shear crack propagation time is increased with the increasing temperature while the stable shear crack propagation rate is decreased with the increasing temperature,since high temperature can increase the shear(Mode Ⅱ) fracture toughness and prevent the crack growth.It is necessary to ensure the ligament of specimen long enough to measure the maximum unstable crack propagation rate of rock.
基金Project supported by Doctoral Study Courses Foundation and Post-Doctoral Scientific Foundation .
文摘The strata movement induced by sub-critical extraction is a problem not receiving due attention because of its relatively small magnitude of deformation. However, with the increase of mining depth, sub-critical extraction has become a general phenomenon. This calls for an in-depth investigation into the characteristics of ground movements observed under different extents of sub-critical extraction, so as to determine the appropriate mining technique for use. Following a discussion of the factors influencing the extent of super-critical extraction, the super-critical extraction extent evaluation criteria was presented, the characteristics and laws of the strata and ground movements caused by such an extraction condition were systematically analyzed, and the mechanism of surface subsidence induced by sub-critical extraction was revealed. The result of study may serve as a basis for the development of the strata and ground movement prediction model and the mining techniques appropriate for use at depth beneath surface structures and buildings.
文摘In reactor physics tests, it is important to monitor sub-criticality continuously during criticality approach. Reactivity measurements by the inverse kinetics method are widely used during the operation of a nuclear reactor. This technique is successfully applied at sufficiently high power level or to a core without an external neutron source where the neutron source term in point reactor kinetics equations may be neglected. For operation at low power levels or in the sub-critical domain, the increase in the fluctuation of the neutron signal may cause difficulties in the evaluation of reactivity and the effect of direct emission from the external neutron source may not be neglected. Therefore, contribution of the neutron source must be taken into account and this implies knowledge of a quantity proportional to the source strength, which calls the source term and then it should be determined. The research work has been conducted to measure reactivity with source term using a dedicated reactivity measurement system by the Least Square Inverse Kinetics Method (LSIKM). Application to a simulator of HANARO research reactor, Korea Atomic Energy Research Institute (KAERI), with known source strength and reactivity worth has showed consistent and satisfactory agreement.
基金This work was supported by the NSFCShanxi coal based low carbon joint fund(U1810209)the Natural Science Foundation of Shanxi Province(201901D111006).
文摘The co-liquefaction behaviors of cotton seed(CS)and flos populi(FP)were investigated in the sub-critical water/ethanol mixed solvent using the medical stone(MS)based additives.Oil products were characterized using FTIR,GC-MS,1HNMR,and 13CNMR techniques.The test results showed that the synergistic effect of co-liquefaction was obvious when the ratio of cotton seed and flospopuli was 1:1 without additives.The additives,such as 12-phosphotungstic acid(PW12),HZSM-5,PW12/HZSM-5 and modified medical stone(MS),PW12/MS,Ni/MS,Co/MS,Mo/MS and Co-Mo/MS,could increase the bio-oil yield;and the modified MS resulted in higher liquefied oil yield than that achieved by MS.Furthermore,additives such as Ni/MS,Mo/MS,and Co-Mo/MS also could increase the yield of aliphatic hydrocarbons in liquefied oil.The addition of Co-Mo/MS could lead to a highest liquefied oil yield of 28.8%,while the additive of PW12/HZSM-5 could result in a highest total conversion of 81.6%.Results also revealed that additives,such as PW12/MS,PW12,PW12/HZSM-5,Ni/MS,Co/MS,Mo/MS,and Co-Mo/MS,could increase the H2 production and decrease the CO2 production in gas products.
基金Supported by 2016 Instrument Functional Development Project of Lanzhou Regional Center of Resources and Environmental Science Instrument,CAS(2018gl11)
文摘[Objectives] To study the optimal conditions for extracting procyanidins fromLycium ruthenicum Murr. with sub-critical fluid R134 a( 1,1,1,2-tetrafluoroethane) in 1 L extraction kettle. [Methods]Taking the extraction rate of procyanidins as an indicator,the influence of pressure,temperature,and extraction time on extraction rate of procyanidins fromL. Ruthenicum Murr. was studied by single factor experimental methods and orthogonal array design. [Results]The order of factors affecting extraction rate of procyanidins was extraction temperature > extraction pressure > extraction time. The optimum extraction conditions were as follows: the extraction rate of procyanidins fromL. ruthenicum Murr. was the highest with extraction pressure of 1. 2 MPa,extraction temperature of 50℃ and extraction time of 90 min. The content of procyanidins in L. ruthenicum Murr. from different producing areas was determined by vanillin-HCl method under the optimal conditions. [Conclusions] The method has the advantages of easy operation,good selectivity,low extraction temperature and high extraction efficiency,which is suitable for extraction of procyanidins in L. ruthenicum Murr.
文摘Sub-critical water extraction is a brand-new separation technology. This paper mainly discussed the principle, advantages of sub-critical water extraction, and its applications ranging from the medicinal plants traditionally used in Europe and Asia to produce pharmaceutical extracts (such as volatile oil, tannins, flavonoids, anthraquinone, lactone, etc.). Meanwhile, the prospect of sub-critical water extraction in plant extractives is also explored. It will be widely used in the field of medical plants, bringing huge economic benefits, environmental benefits and social benefits.
基金supported by the National Natural Science Foundation of China(No.11875328).
文摘Deuteron-driven spallation targets have garnered attention recently because they can provide high-energy neutrons to transmute long-lifetime fission products.In this study,the Geant4 toolkit was used to simulate the inter-action between a deuteron beam at 500 MeV and a com-posite target composed of alternating lead-bismuth eutectic(LBE)and water.The water was used because it may be employed as a target coolant.The energy spectrum,neu-tron yield,average energy,and total energy of the emitted neutrons were calculated for different thicknesses and thickness ratios between the LBE and water.For a constant target thickness,the neutron yield increases with an increasing thickness ratio of LBE to H 2 O,while the aver-age energy of the emitted neutrons decreases with an increasing in the aforementioned thickness ratio.These two aspects support the use of a pure target,either LBE or water.However,with an increasing LBE-to-H 2 O thickness ratio,the total energy of the emitted neutrons increases and then decreases.This result supports the addition of water into the LBE target.The angular distributions of the emitted neutrons show that the rear of the target is suit-able for loading nuclear waste containing minor actinides and long-lifetime fission products.
基金the financial support of the German Research Foundation(DFG)under the project AN 1245/1the financial support of the Helmholtz association through the programmes HGF 34“EMR-Energy efficiency,materials and resources”and“Virtual Materials Design”(VirtMat)Pieces of this work were performed on the computational resource ForHLR II,funded by the Ministry of Science,Research and Arts of Baden-Wuerttemberg and the DFG。
文摘Transformations accompanying shape-instability govern the morphological configuration and distribution of the phases in a microstructure.Owing to the influence of the microstructure on the properties of a material,in the present work,the stability of three-dimensional rods in a‘representative'polycrystalline system is extensively analysed.A multiphase-field model,which recovers the physical laws and sharpinterface relations,and includes grain boundary diffusion,is adopted to investigate the morphological evolution of the precipitate.Moreover,the efficiency of the numerical approach is ensured by establishing the volume-preserving chemical equilibrium through the incorporation TCFe8(CALPHAD)data and solving phase-field evolution in the Allen-Cahn framework.The morphological evolution of the rod in the representative multiphase system exhibits a unique transformation mechanism which is significantly different from the evolution of an isolated finite-structure.It is realised that,in a polycrystalline arrangement,irrespective of the initial size of the rod,the shape-change begins with the energy-minimising events at the triple junctions.This early transformation renders a characteristic morphology at the longitudinal ends of the structure,which introduces sufficient driving-force through the curvature-difference for the subsequent morphological changes.The continued mass transfer to the terminations,ultimately,breaks-off the rod into separate entities that are entangled in the grain boundary.With increase in the aspect ratio of the rod,it is identified that the source of mass transfer,which turns into the ovulation site,shifts from the centre.This increases the number of fragmentation events and introduces satellite particle.The size of the satellite particle is dictated by a definite ovulation criterion,which is ascertained by examining the transformation of different-sized rods.A comprehensive understanding of the transformation kinetics and mechanism governing the morphological evolution of the rods in a polycrystalline system is rendered in this work.
文摘Background In an accelerator-driven sub-critical system(ADS),a strong proton beam from a high-power proton accelerator irradiates a spallation target to produce very intense neutrons for driving a reactor.Currently,the China ADS front-end demo linac(CAFe)facility is being built to provide strong beam with the beam intensity of several mAs.Purpose This paper reports the machine protection system(MPS)of the CAFe facility,which prevents or minimizes the beam-induced damages or the damages from other sources to the machines in the accelerator.Method The MPS of CAFe facility works under the framework of experimental physics and industrial control system(EPICS).The developed machine protection system includes fast protection function and slow interlock function,where the fast function is performed by FPGA controller and the slow function is performed by PLC controller.Results Based on the reports on the status of all relevant subsystems,MPS will either perform an emergency shutdown of the beam or machine or will permit normal operation.When an emergency shutdown of the beam is needed,MPS switches off the ion source or switches on the chopper.In addition to its protective role,MPS will also trace the origin of an emergency shutdown.Conclusions The developed MPS has played an important role during the commissioning and successful operation of the CAFe facility at the end of 2019.
