The tensile-shear interactive damage(TSID)model is a novel and powerful constitutive model for rock-like materials.This study proposes a methodology to calibrate the TSID model parameters to simulate sandstone.The bas...The tensile-shear interactive damage(TSID)model is a novel and powerful constitutive model for rock-like materials.This study proposes a methodology to calibrate the TSID model parameters to simulate sandstone.The basic parameters of sandstone are determined through a series of static and dynamic tests,including uniaxial compression,Brazilian disc,triaxial compression under varying confining pressures,hydrostatic compression,and dynamic compression and tensile tests with a split Hopkinson pressure bar.Based on the sandstone test results from this study and previous research,a step-by-step procedure for parameter calibration is outlined,which accounts for the categories of the strength surface,equation of state(EOS),strain rate effect,and damage.The calibrated parameters are verified through numerical tests that correspond to the experimental loading conditions.Consistency between numerical results and experimental data indicates the precision and reliability of the calibrated parameters.The methodology presented in this study is scientifically sound,straightforward,and essential for improving the TSID model.Furthermore,it has the potential to contribute to other rock constitutive models,particularly new user-defined models.展开更多
In this study,to prepare a series of activated carbon-supported metals for the catalytic reduction of NO_x to N_2 in excess O_2,activated carbons derived from lignocellulosic and herbaceous biomasses were selected as ...In this study,to prepare a series of activated carbon-supported metals for the catalytic reduction of NO_x to N_2 in excess O_2,activated carbons derived from lignocellulosic and herbaceous biomasses were selected as the reducing agents,and alkali and transition metals were used as the catalytic active phases.The effects of the type of biomass,carbonization temperature and catalyst composition on NO_x reduction efficiency were analyzed in a fixed-bed flow reactor.The results showed that two temperature regimes are present for the NO_x-carbon reaction:at temperatures below 250°C,the NO_x adsorption process on the carbon surface was predominant,whereas true NO_x reduction by carbon occurred at temperatures above 250°C,producing N_2,CO_2 and CO.The influence of the carbonization temperature on carbon reactivity depended on the effect of the carbonization temperature on the carbon surface area and the reduction of the metal species on carbon.All studied metals catalyzed both NO_xand O_2reduction by carbon,and potassium could strongly enhance the C-NO_x reaction without substantial carbon consumption by O_2.Moreover,the potassium supported by sawdust-derived activated carbon exhibited higher selectivity and capacity towards NO_x reduction than did its previously reported coal-derived counterparts.These properties were ascribed to the high dispersion of the active potassium species on the carbon surface,as observed through the comparison of X-ray photoelectron spectroscopy and powder X-ray diffraction results for the carbons made from biomass and coal-based precursors.展开更多
Tunnels in fractured rock masses are typically damaged by dynamic disturbances from various directions.To investigate the influence of blasting load directions on the stability of a tunnel with a precrack nearby,blast...Tunnels in fractured rock masses are typically damaged by dynamic disturbances from various directions.To investigate the influence of blasting load directions on the stability of a tunnel with a precrack nearby,blasting tests were conducted on the physical models of an external crack around a tunnel(ECT)in this study.Failure modes of the tunnels were analysed based on stress wave theory.The Riedel-Hiermaier-Thoma(RHT)material model was employed to perform the numerical simulations on ECT models.Stress distribution around the tunnels and final failure patterns of the tunnels were characterised.The results show that,under blasting loads,the pre-crack propagates and then new cracks initiates on the incident side of the tunnel.These cracks extend towards each other and eventually coalesce.Blasting load directions significantly influence the ultimate failure mode of the tunnel in the fractured rock masses.The new cracks on the shadow side of the tunnel appear at different positions when the blasting stress waves come from various directions.The results are meaningful to the analysis of tunnel stability and optimisation of the tunnel support scheme.展开更多
Three-dimensional rock fracture induced by blasting is a highly complex problem and has received considerable attention in geotechnical engineering.The material point method is firstly applied to treat this challengin...Three-dimensional rock fracture induced by blasting is a highly complex problem and has received considerable attention in geotechnical engineering.The material point method is firstly applied to treat this challenging task.Some inherent weaknesses can be overcome by coupling the generalized interpolation material point(GIMP)and the convected particle domain interpolation technique(CPDI).For the media in the borehole,unchanged GIMP-type particles are used to guarantee a homogenous blast pressure.CPDITetrahedron type particles are employed to avoid the fake numerical fracture near the borehole for the rock material.A blasting experiment using three-dimensional single-borehole rock was simulated to examine the applicability of the coupled model under realistic loading and boundary conditions.A good agreement was achieved between the simulation and experimental results.Moreover,the mechanism of three-dimensional rock fracture was analyzed.It was concluded that rock particle size and material parameters play an important role in rock damage.The reflected tensile waves cause severe damage in the lower part of the model.Rayleigh waves occur on the top face of the rock model to induce a hoop failure band.展开更多
A new ratiometric fluorescent sensor based on the bifunctional carbon quantum dots(CQDs)@metal-organic framework(MOF)nanocomposite possessing peroxidase-mimicking catalytic and luminescent characteristics was develope...A new ratiometric fluorescent sensor based on the bifunctional carbon quantum dots(CQDs)@metal-organic framework(MOF)nanocomposite possessing peroxidase-mimicking catalytic and luminescent characteristics was developed for hydrogen peroxide(H_(2)O_(2))and cholesterol detection.The incorporation of fluorescent CQDs into the cavities of MIL-101(Fe)MOF with peroxidase-like activities endows the nanocomposite with bifunctional properties.The CQDs@MOF can oxidize o-phenylene-diamine to 2,3-diaminophenolazine by H_(2)O_(2)with yellow fluorescence(556 nm).Meantime,the intrinsic fluorescence signal(455 nm)of CQDs@MOF is inhibited due to the inner filter effect.Therefore,the ratio of the fluorescent intensity is employed as the signal output to construct the H_(2)O_(2)ratiometric biosensor.In addition,the cholesterol can be determined by the ratiometric sensor with high sensitivity.In addition,the total cholesterol in human serum is determined with high accuracy using our ratiometric biosensor.This ratiometric fluorescent platform based on the bifunctional CQDs@MOF provides new insights in the field of bio-sensing.展开更多
Hierarchical ZSM-5(HZ)molecular sieves based on fly ash were synthesized using a method combining water heat treatment with step-by-step calcination.The coupling catalysts between La_(1-x)Ce_(x)Mn_(0.8)-Ni_(0.2)O_(3)(...Hierarchical ZSM-5(HZ)molecular sieves based on fly ash were synthesized using a method combining water heat treatment with step-by-step calcination.The coupling catalysts between La_(1-x)Ce_(x)Mn_(0.8)-Ni_(0.2)O_(3)(x≤0.5)perovskites and HZ were prepared through the impregnation method,which were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),N_(2)adsorption,X-ray photoelectron spectroscopy(XPS),NH3-temperature programmed desoprtion(NH3-TPD),H_(2)-temperature programmed reduction(H_(2)-TPR)and O_(2)-TPD techniques and investigated regarding pentanal oxidation at 120-390℃to explore the effects of Ce doping on the catalytic activity and the active oxygen species of the coupling catalysts,meanwhile,the reaction mechanism and pathway of pentanal oxidation were also studied.The results reveal that Ce substitution at La sites can change the electronic interactions between all the elements and promote the electronic transfer among La,Ce,Ni,Mn and HZ,influencing directly the physicochemical characteristics of the catalysts.Moreover,the amount and transfer ability of surface adsorbed oxygen(O_(2)-and O-)regarded as the reactive oxygen species and the low temperature reducibility are the main influence factors in pentanal oxidation.Additionally,La_(0.8)Ce_(0.2)Mn_(0.8)Ni_(0.2)O_(3)/HZ exhibits the best catalytic activity and deep oxidation capacity as well as a better water resistance due to its larger amount of surface adsorbed oxygen species and higher low temperature reducibility.What’s more,appropriate Ce substitution can significantly enhance the amount of O_(2)-ions,which can distinctly enhance the catalytic activity of the catalyst,and moderate acid strength and appropriate acid amount can also facilitate the improvement of the pentanal oxidation activity.It is found that there is a synergic catalytic effect between surface acidity and redox ability of the catalyst.According to the in situ DRIFTS and GC/MS analyses,pentanal can be oxidized gradually to CO_(2)and H_(2)O by the surface oxygen species with the form of adsorption in air following the Langmuir-Hinshelwood(L-H)reaction mechanism.Two reaction pathways for the pentanal oxidation process are proposed,and the conversion of the formates to carbonates may be one of the main rate-determining steps.展开更多
Skyrmions are nano-scale quasi-particles with topological protection,which have potential applications in next-generation spintronics-based information storage.Numerous papers have been published to review various asp...Skyrmions are nano-scale quasi-particles with topological protection,which have potential applications in next-generation spintronics-based information storage.Numerous papers have been published to review various aspects of skyrmions,including physics,materials and applications.However,no review paper has focused on rare metals which play important roles in nucleating and manipulating skyrmions and other topological states.In this paper,various roles of rare metals have been classified and summarized,which can tune Curie temperature(TC),Dzyaloshinskii-Moriya interaction(DMI),magnetocrystalline anisotropy,Ruderman-Kittel-Kasuya-Yosida(RKKY)interaction and four-spin interaction so as to trigger the generation of skyrmions and other topological spin structures.The materials covered include typical B20 crystals,various layered systems with interfacial DMI,frustrated materials,antiferromagnets,ferrimagnets,twodimensional(2D)materials,etc.In addition,the rare-earth(RE)permanent magnets can provide an energy barrier and enrich the dynamic behaviors of skyrmions,which has also been reviewed.展开更多
基金funded by the National Natural Science Foundation of China(Grant No.12272247)National Key Project(Grant No.GJXM92579)Major Research and Development Project of Metallurgical Corporation of China Ltd.in the Non-Steel Field(Grant No.2021-5).
文摘The tensile-shear interactive damage(TSID)model is a novel and powerful constitutive model for rock-like materials.This study proposes a methodology to calibrate the TSID model parameters to simulate sandstone.The basic parameters of sandstone are determined through a series of static and dynamic tests,including uniaxial compression,Brazilian disc,triaxial compression under varying confining pressures,hydrostatic compression,and dynamic compression and tensile tests with a split Hopkinson pressure bar.Based on the sandstone test results from this study and previous research,a step-by-step procedure for parameter calibration is outlined,which accounts for the categories of the strength surface,equation of state(EOS),strain rate effect,and damage.The calibrated parameters are verified through numerical tests that correspond to the experimental loading conditions.Consistency between numerical results and experimental data indicates the precision and reliability of the calibrated parameters.The methodology presented in this study is scientifically sound,straightforward,and essential for improving the TSID model.Furthermore,it has the potential to contribute to other rock constitutive models,particularly new user-defined models.
基金Supported by the National Natural Science Foundation of China(21507119)the Key Technology Research and Development Program of Qinghai Province(2012-J-144)the National High Technology Research and Development Program of China(2012AA06A11303)
文摘In this study,to prepare a series of activated carbon-supported metals for the catalytic reduction of NO_x to N_2 in excess O_2,activated carbons derived from lignocellulosic and herbaceous biomasses were selected as the reducing agents,and alkali and transition metals were used as the catalytic active phases.The effects of the type of biomass,carbonization temperature and catalyst composition on NO_x reduction efficiency were analyzed in a fixed-bed flow reactor.The results showed that two temperature regimes are present for the NO_x-carbon reaction:at temperatures below 250°C,the NO_x adsorption process on the carbon surface was predominant,whereas true NO_x reduction by carbon occurred at temperatures above 250°C,producing N_2,CO_2 and CO.The influence of the carbonization temperature on carbon reactivity depended on the effect of the carbonization temperature on the carbon surface area and the reduction of the metal species on carbon.All studied metals catalyzed both NO_xand O_2reduction by carbon,and potassium could strongly enhance the C-NO_x reaction without substantial carbon consumption by O_2.Moreover,the potassium supported by sawdust-derived activated carbon exhibited higher selectivity and capacity towards NO_x reduction than did its previously reported coal-derived counterparts.These properties were ascribed to the high dispersion of the active potassium species on the carbon surface,as observed through the comparison of X-ray photoelectron spectroscopy and powder X-ray diffraction results for the carbons made from biomass and coal-based precursors.
基金funded by the National Natural Science Foundation of China(Grant No.U19A2098)the open fund of MOE Key Laboratory of Deep Underground Science and Engineering(Grant No.DESEYU202101)the Sichuan Science and Technology Program(Grant No.2021YJ0511)。
文摘Tunnels in fractured rock masses are typically damaged by dynamic disturbances from various directions.To investigate the influence of blasting load directions on the stability of a tunnel with a precrack nearby,blasting tests were conducted on the physical models of an external crack around a tunnel(ECT)in this study.Failure modes of the tunnels were analysed based on stress wave theory.The Riedel-Hiermaier-Thoma(RHT)material model was employed to perform the numerical simulations on ECT models.Stress distribution around the tunnels and final failure patterns of the tunnels were characterised.The results show that,under blasting loads,the pre-crack propagates and then new cracks initiates on the incident side of the tunnel.These cracks extend towards each other and eventually coalesce.Blasting load directions significantly influence the ultimate failure mode of the tunnel in the fractured rock masses.The new cracks on the shadow side of the tunnel appear at different positions when the blasting stress waves come from various directions.The results are meaningful to the analysis of tunnel stability and optimisation of the tunnel support scheme.
基金This research was funded by the Natural Science Foundation of Sichuan,China(No.2022NSFSC1915)the National Natural Science Foundation of China(No.U19A2098)+1 种基金State Key Laboratory of Precision Blasting and Hubei Key Laboratory of Blasting Engineering,Jianghan University(No.PBSKL2022B06)the Fundamental Research Funds for the Central Universities。
文摘Three-dimensional rock fracture induced by blasting is a highly complex problem and has received considerable attention in geotechnical engineering.The material point method is firstly applied to treat this challenging task.Some inherent weaknesses can be overcome by coupling the generalized interpolation material point(GIMP)and the convected particle domain interpolation technique(CPDI).For the media in the borehole,unchanged GIMP-type particles are used to guarantee a homogenous blast pressure.CPDITetrahedron type particles are employed to avoid the fake numerical fracture near the borehole for the rock material.A blasting experiment using three-dimensional single-borehole rock was simulated to examine the applicability of the coupled model under realistic loading and boundary conditions.A good agreement was achieved between the simulation and experimental results.Moreover,the mechanism of three-dimensional rock fracture was analyzed.It was concluded that rock particle size and material parameters play an important role in rock damage.The reflected tensile waves cause severe damage in the lower part of the model.Rayleigh waves occur on the top face of the rock model to induce a hoop failure band.
基金support from the NSFC(21705141,22076161,21675140,21575124)the Green Yang Jinfeng Talent Project of Yangzhou+1 种基金the High-end talent Support Program of Yangzhou Universitythe Interdisciplinary Research Foundation for Chemistry Discipline of Targeted Support of Yangzhou University(yzuxk202009)
文摘A new ratiometric fluorescent sensor based on the bifunctional carbon quantum dots(CQDs)@metal-organic framework(MOF)nanocomposite possessing peroxidase-mimicking catalytic and luminescent characteristics was developed for hydrogen peroxide(H_(2)O_(2))and cholesterol detection.The incorporation of fluorescent CQDs into the cavities of MIL-101(Fe)MOF with peroxidase-like activities endows the nanocomposite with bifunctional properties.The CQDs@MOF can oxidize o-phenylene-diamine to 2,3-diaminophenolazine by H_(2)O_(2)with yellow fluorescence(556 nm).Meantime,the intrinsic fluorescence signal(455 nm)of CQDs@MOF is inhibited due to the inner filter effect.Therefore,the ratio of the fluorescent intensity is employed as the signal output to construct the H_(2)O_(2)ratiometric biosensor.In addition,the cholesterol can be determined by the ratiometric sensor with high sensitivity.In addition,the total cholesterol in human serum is determined with high accuracy using our ratiometric biosensor.This ratiometric fluorescent platform based on the bifunctional CQDs@MOF provides new insights in the field of bio-sensing.
基金Project supported by the National Key Research and Development Program of China(2017YFC0212606,2017YFC0211503,2016YFC0204102)the National Natural Science Foundation of China(51608500)。
文摘Hierarchical ZSM-5(HZ)molecular sieves based on fly ash were synthesized using a method combining water heat treatment with step-by-step calcination.The coupling catalysts between La_(1-x)Ce_(x)Mn_(0.8)-Ni_(0.2)O_(3)(x≤0.5)perovskites and HZ were prepared through the impregnation method,which were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),N_(2)adsorption,X-ray photoelectron spectroscopy(XPS),NH3-temperature programmed desoprtion(NH3-TPD),H_(2)-temperature programmed reduction(H_(2)-TPR)and O_(2)-TPD techniques and investigated regarding pentanal oxidation at 120-390℃to explore the effects of Ce doping on the catalytic activity and the active oxygen species of the coupling catalysts,meanwhile,the reaction mechanism and pathway of pentanal oxidation were also studied.The results reveal that Ce substitution at La sites can change the electronic interactions between all the elements and promote the electronic transfer among La,Ce,Ni,Mn and HZ,influencing directly the physicochemical characteristics of the catalysts.Moreover,the amount and transfer ability of surface adsorbed oxygen(O_(2)-and O-)regarded as the reactive oxygen species and the low temperature reducibility are the main influence factors in pentanal oxidation.Additionally,La_(0.8)Ce_(0.2)Mn_(0.8)Ni_(0.2)O_(3)/HZ exhibits the best catalytic activity and deep oxidation capacity as well as a better water resistance due to its larger amount of surface adsorbed oxygen species and higher low temperature reducibility.What’s more,appropriate Ce substitution can significantly enhance the amount of O_(2)-ions,which can distinctly enhance the catalytic activity of the catalyst,and moderate acid strength and appropriate acid amount can also facilitate the improvement of the pentanal oxidation activity.It is found that there is a synergic catalytic effect between surface acidity and redox ability of the catalyst.According to the in situ DRIFTS and GC/MS analyses,pentanal can be oxidized gradually to CO_(2)and H_(2)O by the surface oxygen species with the form of adsorption in air following the Langmuir-Hinshelwood(L-H)reaction mechanism.Two reaction pathways for the pentanal oxidation process are proposed,and the conversion of the formates to carbonates may be one of the main rate-determining steps.
基金financially supported by the National Natural Science Foundation of China (Nos. 51771127, 52171188 52111530143, 12104327, 51901081, 11974298 and 61961136006)the National Key Research and Development Program of China (No. 2020YFA0309300)+6 种基金Sichuan Science and Technology Program (Application No. 21ZYZYTS0077)the Science and Technology Program of Guangzhou (No. 202002030052)Guangdong Special Support Project (No. 2019BT02X030)Shenzhen Fundamental Research Fund (No. JCYJ20210324120213037)Shenzhen Peacock Group Plan (No. KQTD20180413181702403)Pearl River Recruitment Program of Talents (No. 2017GC010293)the Grants-in-Aid for Scientific Research from JSPS KAKENHI (Nos. JP20F20363, JP21H01364 and JP21K18872)
文摘Skyrmions are nano-scale quasi-particles with topological protection,which have potential applications in next-generation spintronics-based information storage.Numerous papers have been published to review various aspects of skyrmions,including physics,materials and applications.However,no review paper has focused on rare metals which play important roles in nucleating and manipulating skyrmions and other topological states.In this paper,various roles of rare metals have been classified and summarized,which can tune Curie temperature(TC),Dzyaloshinskii-Moriya interaction(DMI),magnetocrystalline anisotropy,Ruderman-Kittel-Kasuya-Yosida(RKKY)interaction and four-spin interaction so as to trigger the generation of skyrmions and other topological spin structures.The materials covered include typical B20 crystals,various layered systems with interfacial DMI,frustrated materials,antiferromagnets,ferrimagnets,twodimensional(2D)materials,etc.In addition,the rare-earth(RE)permanent magnets can provide an energy barrier and enrich the dynamic behaviors of skyrmions,which has also been reviewed.
