Terahertz biotechnology has been increasingly applied in various biomedical fields and has especially shown great potential for application in brain sciences.In this article,we review the development of terahertz biot...Terahertz biotechnology has been increasingly applied in various biomedical fields and has especially shown great potential for application in brain sciences.In this article,we review the development of terahertz biotechnology and its applications in the field of neuropsychiatry.Available evidence indicates promising prospects for the use of terahertz spectroscopy and terahertz imaging techniques in the diagnosis of amyloid disease,cerebrovascular disease,glioma,psychiatric disease,traumatic brain injury,and myelin deficit.In vitro and animal experiments have also demonstrated the potential therapeutic value of terahertz technology in some neuropsychiatric diseases.Although the precise underlying mechanism of the interactions between terahertz electromagnetic waves and the biosystem is not yet fully understood,the research progress in this field shows great potential for biomedical noninvasive diagnostic and therapeutic applications.However,the biosafety of terahertz radiation requires further exploration regarding its two-sided efficacy in practical applications.This review demonstrates that terahertz biotechnology has the potential to be a promising method in the field of neuropsychiatry based on its unique advantages.展开更多
This study investigated the effect of konjac glucomannan(KGM)on the flotation separation of calcite and scheelite.Micro-flotation tests showed that under the action of 50 mg/L KGM,the floatability of calcite notably d...This study investigated the effect of konjac glucomannan(KGM)on the flotation separation of calcite and scheelite.Micro-flotation tests showed that under the action of 50 mg/L KGM,the floatability of calcite notably decreased,while the impact on scheelite was negligible,resulting in a recovery difference of 82.53%.Fourier transform infrared(FTIR)spectroscopy and atomic force micro-scopy(AFM)analyses indicated the selective adsorption of KGM on the calcite surface.Test results of the zeta potential and UV-visible absorption spectroscopy revealed that KGM prevented the adsorption of sodium oleate on the calcite surface.X-ray photoelectron spec-troscopy(XPS)analysis further confirmed the chemical adsorption of KGM on the calcite surface and the formation of Ca(OH)_(2).The density functional theory(DFT)simulation results were consistent with the flotation tests,demonstrating the strong adsorption perform-ance of KGM on the calcite surface.This study offers a pathway for highly sustainable and cost-effective mineral processing by utilizing the unique properties of biopolymers such as KGM to separate valuable minerals from gangue minerals.展开更多
When a perpendicular magnetic field penetrates a thin slab of a type-Ⅱ superconductor it produces vortices,with one vortex per flux quantum,h/2e.The vortices interact repulsively and form an ordered array(Abrikosov l...When a perpendicular magnetic field penetrates a thin slab of a type-Ⅱ superconductor it produces vortices,with one vortex per flux quantum,h/2e.The vortices interact repulsively and form an ordered array(Abrikosov lattice)in clean systems,while strong disorder changes the lattice into a vortex glass.The collective vortex dynamics is extremely vulnerable to external perturbations.Consequently,although of great importance,experimental observation is limited.Here we investigate type-Ⅱ superconducting films(PdBi_(2)and NbSe_(2))with surface acoustic waves(SAWs)at mK temperature.When sweeping the magnetic field at an extremely slow rate,we observe a series of spikes in the attenuation and velocity of the SAW,on average separated in field by approximately Hc1.We propose the following scenario:The vortex-free region at the edges of the film produces an edge barrier across which the vortices can enter or leave.When the applied field changes,the induced supercurrents flowing along this edge region lowers this barrier until there is an instability.At that point,vortices avalanche into(or out of)the bulk and change the vortex crystal,suggested by the sharp jump in each such spike.The vortices then gradually relax to a new stable pinned configuration,leading to a~30 s relaxation after the jump.Our observation enriches the limited experimental evidence on the important topic of real-time vortex dynamics in superconductors.展开更多
A promising way to realize controlled nuclear fusion involves the use of magnetic fields to control and confine the hot plasma configuration.This approach requires superconductor magnets operating above 15 T for the n...A promising way to realize controlled nuclear fusion involves the use of magnetic fields to control and confine the hot plasma configuration.This approach requires superconductor magnets operating above 15 T for the next generation of fusion devices.Due to their high in-field transport current capacity,rare-Earth barium copper oxide(REBCO)coated conductors are promising materials for manufacturing of cable-in-conduit conductors(CICCs)for fusion.However,the high-aspect-ratio geometry makes it difficult to find a multi-tape CICC configuration that fulfills the high engineering current density requirements while retaining enough flexibility for winding large-scale magnets.Moreover,the multilayer structure and inherent brittleness make the REBCO tapes susceptible to degradation during CICC manufacturing and operation.For more than a decade,the development of a reliable REBCO-based CICC that can sustain the huge combined mechanical,thermal,and Lorentz loads without degradation has been ongoing,albeit with limited progress.In this paper,we report on a prototype REBCO CICC that can withstand an applied cyclic Lorentz load of at least 830 kN·m^(-1),corresponding to a transport current of 80 kA at 10.85 T and 4.5 K.To our knowledge,this is the highest load achieved to date.The CICC uses 288 tapes wound into six strengthened sub-cables,making it capable of having a current sharing temperature,Tcs,of around 39 and 20 K when operated under 10.85 T with a current of 40 and 80 kA,respectively.Scaled to a 20-T peak field and 46.5-kA transport current,this provides a temperature margin of over 10 K with respect to an operating temperature of 4.5 K.In addition,no perceptible transport current performance degradation was observed after cyclic Lorentz loading,cyclic warm-up/cool-down(WUCD),and quench campaigns.The proposed REBCO CICC is a milestone in the development of high-temperature superconductors for large-scale and high-field magnet applications.展开更多
Grassland degradation presents overwhelming challenges to biodiversity,ecosystem services,and the socioeconomic sustainability of dependent communities.However,a comprehensive synthesis of global knowledge on the fron...Grassland degradation presents overwhelming challenges to biodiversity,ecosystem services,and the socioeconomic sustainability of dependent communities.However,a comprehensive synthesis of global knowledge on the frontiers and key areas of grassland degradation research has not been achieved due to the limitations of traditional scientometrics methods.The present synthesis of information employed BERTopic,an advanced natural language processing tool,to analyze the extensive ecological literature on grassland degradation.We compiled a dataset of 4,504 publications from the Web of Science core collection database and used it to evaluate the geographic distribution and temporal evolution of different grassland types and available knowledge on the subject.Our analysis identified key topics in the global grassland degradation research domain,including the effects of grassland degradation on ecosystem functions,grassland ecological restoration and biodiversity conservation,erosion processes and hydrological models in grasslands,and others.The BERTopic analysis significantly outperforms traditional methods in identifying complex and evolving topics in large datasets of literature.Compared to traditional scientometrics analysis,BERTopic provides a more comprehensive perspective on the research areas,revealing not only popular topics but also emerging research areas that traditional methods may overlook,although scientometrics offers more specificity and detail.Therefore,we argue for the simultaneous use of both approaches to achieve more systematic and comprehensive assessments of specific research areas.This study represents an emerging application of BERTopic algorithms in ecological research,particularly in the critical research focused on global grassland degradation.It also highlights the need for integrating advanced computational methods in ecological research in this era of data explosion.Tools like the BERTopic algorithm are essential for enhancing our understanding of complex environmental problems,and it marks an important stride towards more sophisticated,data-driven analysis in ecology.展开更多
Molecular dynamics(MD)simulation is employed to investigate the deformation behavior under various loading paths and strain rates of nanocrystalline magnesium(NC Mg)with[0001]texture.Atomic-scale structural evolution ...Molecular dynamics(MD)simulation is employed to investigate the deformation behavior under various loading paths and strain rates of nanocrystalline magnesium(NC Mg)with[0001]texture.Atomic-scale structural evolution of NC Mg was performed under uniaxial and biaxial loadings.In tension process,compression twins and basal slip dominate,while the compression process is dominated by tension twins.The activation mechanism of twinning is highly sensitive to the loading path and grain orientation.Meanwhile,the effect of strain rate on the structural evolution of NC Mg was investigated.It is found that the effect of strain rate on the plastic deformation of NC Mg is reflected through the plasticity delays and the way to release the stress.As the strain rate decreases,the plastic deformation mechanism gradually changes from intragranular to grain boundary.Some significant potential deformation mechanisms in the loading process were studied.It is observed that{1121}twins nucleated inside the grains,and the thickening process is completed by basal〈a〉slip of the twin boundary.The strain compatibility between twins is automatically optimized with loading.Moreover,the detwinning mechanism caused by the interaction between twins and basal stacking faults is clarified.展开更多
The fracture behavior of natural fracture in the geological reservoir subjected to filling property,affects the crack initiation and propagation under stress perturbation.Partial filling flaws were intermediate betwee...The fracture behavior of natural fracture in the geological reservoir subjected to filling property,affects the crack initiation and propagation under stress perturbation.Partial filling flaws were intermediate between open fractures and filled fractures,the fracture response may be worth exploring.In this work,the effect of the filling property of sandstone with partial filling flaws on the fracture behavior was systematically investigated based on three-point bending tests and the numerical approach of discrete element method(DEM).In the laboratory,semi-circular three-point bending tests were carried out with partial filling flaws of various filling strengths.Based on this,numerical simulations were used to further investigate the effect of the filling ratio and the inclination of the partial filling flaw on the mechanical and fracture responses,and the effect of the partial filling flaw under mixed-mode loading on the fracture mechanism was elucidated coupled with acoustic emission(AE)characteristics.The obtained results showed that the increase in filling strength and filling ratio of partial filling flaw led to an increase in peak strength,with a decreasing trend in peak strength with the inclination of partial filling flaw.In terms of crack propagation pattern,the increasing filling strength of the partial filling flaw induced the transformation of the fracture mechanism toward deflection,with a tortuosity path,while the filling ratio and inclination of partial filling flaw led to fracture mechanism change from deflection to penetration and attraction,accompanied with a larger AE event source in filler.Accordingly,the b-value based on the Gutenberg-Richter equation fluctuated between 5 and 4 at low filling ratio and inclination and remained around 5 at high filling ratio and inclination of partial filling flaw.Related results may provide an application prospective for reservoir stimulation using the natural fracture system.展开更多
Aerosol acidity(pH)plays an important role in the multiphase chemical processes of atmospheric particles.In this study,we demonstrated the seasonal trends of aerosol pH calculated with the ISORROPIA-II model in a coas...Aerosol acidity(pH)plays an important role in the multiphase chemical processes of atmospheric particles.In this study,we demonstrated the seasonal trends of aerosol pH calculated with the ISORROPIA-II model in a coastal city of southeast China.We performed quantitative analysis on the various influencing factors on aerosol pH,and explored the responses of aerosol pH to different PM_(2.5)and O_(3)pollution levels.The results showed that the average aerosol pH was 2.92±0.61,following the order of winter>spring>summer>autumn.Sensitivity tests revealed that SO_(4)^(2−),NH_(x),T and RH triggered the variations of aerosol pH.Quantitative analysis results showed that T(37.9%-51.2%)was the main factors affecting pH variations in four seasons,followed by SO_(4)^(2−)(6.1%-23.7%),NH_(x)(7.2%-22.2%)and RH(0–14.2%).Totally,annual mean meteorological factors(52.9%)and chemical compositions(41.3%)commonly contributed the aerosolpH in the coastal city.The concentrations of PM_(2.5)was positively correlated with aerosol liquid water content(R^(2)=0.53)and aerosol pH(R^(2)=0.26),indicating that the increase in pH was related with the elevated NH_(4)NO_(3)and decreased SO_(4)^(2−),and also the changes of T and RH.The O_(x)(O_(3)+NO_(2))was moderately correlated with aerosol pH(R^(2)=-0.48),attributable to the fact that the proportion of SO_(4)^(2−)increased under high T and low RH conditions.The study strengthened our understanding of the contributions of influencing factors to aerosol pH,and also provided scientific evidences for chemical processes of atmospheric particles in coastal areas.展开更多
The poor degradability and limited recyclability of epoxy resins are key challenges hindering the efficient recycling of ex-service wind turbine blades(EWTBs).Herein,we proposed a selective degradation strategy for di...The poor degradability and limited recyclability of epoxy resins are key challenges hindering the efficient recycling of ex-service wind turbine blades(EWTBs).Herein,we proposed a selective degradation strategy for direct recycling and high-value recovery of epoxy resins by introducing degradable Schiff base groups into the molecular structure and utilizing the resulting oligomers as curing agents.To realize this strategy,a series of Schiff base compounds were synthesized using bio-based vanillin and diamines and subsequently functionalized with epichlorohydrin to yield bio-based epoxy resins.The cured epoxy resins demonstrated remarkable improvements in the mechanical properties of diglycidyl ether of bisphenol-A(DGEBA),with an increases of 44.49%in the tensile strength of 38.55%,bending strength,and impact strength of 71.20%.The introduction of dynamic Schiff base bonds enabled the selective degradation of the vanillin-2,2-bis[4-(4-aminophenoxy)phenyl]propane-based epoxy resin(VBEP)/DGEBA copolymer,producing 84.20% oligomers that can be directly recycled and reused.Replacing 30 wt% of the curing agent with the oligomer increased the tensile strength of the cured sample to 75.40 MPa,surpassing that of the cured DGEBA.Under simulated acid rain and seawater exposure,the copolymer exhibited a service life of 27 years at 40℃,significantly exceeding the currently reported service life of 20 years.This study presents a sustainable strategy for the direct recycling and high-value reuse of epoxy resin,offering a promising solution for EWTBs.展开更多
Massive fracturing fluid injection in reservoir stimulation can alter the fluid pressure field,potentially inducing the faults to slip in an aseismic or seismic phenomenon.In this work,laboratory friction experiments ...Massive fracturing fluid injection in reservoir stimulation can alter the fluid pressure field,potentially inducing the faults to slip in an aseismic or seismic phenomenon.In this work,laboratory friction experiments were performed on split-cutting granite fracture to investigate the effect of fluid pressure on injection-induced slip behavior.The injection experiments spanned a fluid pressure range of 1-20 MPa,which was up to half of the confining pressure.The laboratory results demonstrated that an increase in confining pressure led to a marginal reduction in the friction coefficient,decreasing from a range of 0.70-0.80 at 10 MPa to 0.71-0.75 at 40 MPa.Friction constitutive parameters in experiments with fluid pressure above 10 MPa exhibited a transition from velocity-strengthening to velocity-weakening behavior,while remaining consistently velocity-strengthening below this threshold.Similarly,measurements of dilatancy and critical slip distance exhibited a similar evolution,first increasing and then becoming approximately constant,independent of fluid pressure.The observed microstructural evolution of the split-cutting fractures during slip testing supported these mechanical responses.Post-shear slip,a decrease in the fracture roughness and asperity distribution of the split-cutting fracture was noted,with the decrease in amplitude being more pronounced at high confining pressure.Research may provide a prospect on slip-on faults with fluid pressure.展开更多
基金supported by grants from the National Key R&D Program of China,No.2017YFC0909200(to DC)the National Natural Science Foundation of China,No.62075225(to HZ)+1 种基金Zhejiang Provincial Medical Health Science and Technology Project,No.2023XY053(to ZP)Zhejiang Provincial Traditional Chinese Medical Science and Technology Project,No.2023ZL703(to ZP).
文摘Terahertz biotechnology has been increasingly applied in various biomedical fields and has especially shown great potential for application in brain sciences.In this article,we review the development of terahertz biotechnology and its applications in the field of neuropsychiatry.Available evidence indicates promising prospects for the use of terahertz spectroscopy and terahertz imaging techniques in the diagnosis of amyloid disease,cerebrovascular disease,glioma,psychiatric disease,traumatic brain injury,and myelin deficit.In vitro and animal experiments have also demonstrated the potential therapeutic value of terahertz technology in some neuropsychiatric diseases.Although the precise underlying mechanism of the interactions between terahertz electromagnetic waves and the biosystem is not yet fully understood,the research progress in this field shows great potential for biomedical noninvasive diagnostic and therapeutic applications.However,the biosafety of terahertz radiation requires further exploration regarding its two-sided efficacy in practical applications.This review demonstrates that terahertz biotechnology has the potential to be a promising method in the field of neuropsychiatry based on its unique advantages.
基金supported by the National Natural Science Foundation of China(No.52164022).
文摘This study investigated the effect of konjac glucomannan(KGM)on the flotation separation of calcite and scheelite.Micro-flotation tests showed that under the action of 50 mg/L KGM,the floatability of calcite notably decreased,while the impact on scheelite was negligible,resulting in a recovery difference of 82.53%.Fourier transform infrared(FTIR)spectroscopy and atomic force micro-scopy(AFM)analyses indicated the selective adsorption of KGM on the calcite surface.Test results of the zeta potential and UV-visible absorption spectroscopy revealed that KGM prevented the adsorption of sodium oleate on the calcite surface.X-ray photoelectron spec-troscopy(XPS)analysis further confirmed the chemical adsorption of KGM on the calcite surface and the formation of Ca(OH)_(2).The density functional theory(DFT)simulation results were consistent with the flotation tests,demonstrating the strong adsorption perform-ance of KGM on the calcite surface.This study offers a pathway for highly sustainable and cost-effective mineral processing by utilizing the unique properties of biopolymers such as KGM to separate valuable minerals from gangue minerals.
基金supported by the National Key Research Program of China(Grant Nos.2021YFA1401900,2022YFA1403300,and 2020YFA0309100)the Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0302602 and 2024ZD0300103)+1 种基金the National Natural Science Foundation of China(Grant No.12074073)for samplefabrication and measurementthe support by the The Basic Research Program of the Chinese Academy of Sciences Based on Major Scientific Infrastructures(Grant No.JZHKYPT-2021-08).
文摘When a perpendicular magnetic field penetrates a thin slab of a type-Ⅱ superconductor it produces vortices,with one vortex per flux quantum,h/2e.The vortices interact repulsively and form an ordered array(Abrikosov lattice)in clean systems,while strong disorder changes the lattice into a vortex glass.The collective vortex dynamics is extremely vulnerable to external perturbations.Consequently,although of great importance,experimental observation is limited.Here we investigate type-Ⅱ superconducting films(PdBi_(2)and NbSe_(2))with surface acoustic waves(SAWs)at mK temperature.When sweeping the magnetic field at an extremely slow rate,we observe a series of spikes in the attenuation and velocity of the SAW,on average separated in field by approximately Hc1.We propose the following scenario:The vortex-free region at the edges of the film produces an edge barrier across which the vortices can enter or leave.When the applied field changes,the induced supercurrents flowing along this edge region lowers this barrier until there is an instability.At that point,vortices avalanche into(or out of)the bulk and change the vortex crystal,suggested by the sharp jump in each such spike.The vortices then gradually relax to a new stable pinned configuration,leading to a~30 s relaxation after the jump.Our observation enriches the limited experimental evidence on the important topic of real-time vortex dynamics in superconductors.
基金supported by the Comprehensive Research Facility for the Fusion Technology Program of China(2018-000052-73-01-001228)the National Key Research and Development Program of China(2022YFE03150200)+3 种基金the Institute of Energy,Hefei Comprehensive National Science Center(21KZS207)the National Natural Science Foundation of China(52077212)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2021444)the European–China collaboration program on the FUSION magnet.
文摘A promising way to realize controlled nuclear fusion involves the use of magnetic fields to control and confine the hot plasma configuration.This approach requires superconductor magnets operating above 15 T for the next generation of fusion devices.Due to their high in-field transport current capacity,rare-Earth barium copper oxide(REBCO)coated conductors are promising materials for manufacturing of cable-in-conduit conductors(CICCs)for fusion.However,the high-aspect-ratio geometry makes it difficult to find a multi-tape CICC configuration that fulfills the high engineering current density requirements while retaining enough flexibility for winding large-scale magnets.Moreover,the multilayer structure and inherent brittleness make the REBCO tapes susceptible to degradation during CICC manufacturing and operation.For more than a decade,the development of a reliable REBCO-based CICC that can sustain the huge combined mechanical,thermal,and Lorentz loads without degradation has been ongoing,albeit with limited progress.In this paper,we report on a prototype REBCO CICC that can withstand an applied cyclic Lorentz load of at least 830 kN·m^(-1),corresponding to a transport current of 80 kA at 10.85 T and 4.5 K.To our knowledge,this is the highest load achieved to date.The CICC uses 288 tapes wound into six strengthened sub-cables,making it capable of having a current sharing temperature,Tcs,of around 39 and 20 K when operated under 10.85 T with a current of 40 and 80 kA,respectively.Scaled to a 20-T peak field and 46.5-kA transport current,this provides a temperature margin of over 10 K with respect to an operating temperature of 4.5 K.In addition,no perceptible transport current performance degradation was observed after cyclic Lorentz loading,cyclic warm-up/cool-down(WUCD),and quench campaigns.The proposed REBCO CICC is a milestone in the development of high-temperature superconductors for large-scale and high-field magnet applications.
基金financially supported by the First-Class Curriculum Program at the School of Economics and Management,University of the Chinese Academy of Sciencesthe National Natural Science Foundation of China(42041005)the National Social Science Foundation of China(23BTQ054)。
文摘Grassland degradation presents overwhelming challenges to biodiversity,ecosystem services,and the socioeconomic sustainability of dependent communities.However,a comprehensive synthesis of global knowledge on the frontiers and key areas of grassland degradation research has not been achieved due to the limitations of traditional scientometrics methods.The present synthesis of information employed BERTopic,an advanced natural language processing tool,to analyze the extensive ecological literature on grassland degradation.We compiled a dataset of 4,504 publications from the Web of Science core collection database and used it to evaluate the geographic distribution and temporal evolution of different grassland types and available knowledge on the subject.Our analysis identified key topics in the global grassland degradation research domain,including the effects of grassland degradation on ecosystem functions,grassland ecological restoration and biodiversity conservation,erosion processes and hydrological models in grasslands,and others.The BERTopic analysis significantly outperforms traditional methods in identifying complex and evolving topics in large datasets of literature.Compared to traditional scientometrics analysis,BERTopic provides a more comprehensive perspective on the research areas,revealing not only popular topics but also emerging research areas that traditional methods may overlook,although scientometrics offers more specificity and detail.Therefore,we argue for the simultaneous use of both approaches to achieve more systematic and comprehensive assessments of specific research areas.This study represents an emerging application of BERTopic algorithms in ecological research,particularly in the critical research focused on global grassland degradation.It also highlights the need for integrating advanced computational methods in ecological research in this era of data explosion.Tools like the BERTopic algorithm are essential for enhancing our understanding of complex environmental problems,and it marks an important stride towards more sophisticated,data-driven analysis in ecology.
基金supports from the projects by the NSFC[51771166]the Hebei Natural Science Foundation[E2019203452,E2021203011]+3 种基金the key project of department of education of Hebei province[ZD2021107]project of the central government guiding local science and technology development[216Z1001G]Cultivation Project for Basic Research and Innovation of Yanshan University[2021LGZD002]project of State Key Laboratory of Materials Processing and Die&Mould Technology[P2023-004]are gratefully acknowledged.
文摘Molecular dynamics(MD)simulation is employed to investigate the deformation behavior under various loading paths and strain rates of nanocrystalline magnesium(NC Mg)with[0001]texture.Atomic-scale structural evolution of NC Mg was performed under uniaxial and biaxial loadings.In tension process,compression twins and basal slip dominate,while the compression process is dominated by tension twins.The activation mechanism of twinning is highly sensitive to the loading path and grain orientation.Meanwhile,the effect of strain rate on the structural evolution of NC Mg was investigated.It is found that the effect of strain rate on the plastic deformation of NC Mg is reflected through the plasticity delays and the way to release the stress.As the strain rate decreases,the plastic deformation mechanism gradually changes from intragranular to grain boundary.Some significant potential deformation mechanisms in the loading process were studied.It is observed that{1121}twins nucleated inside the grains,and the thickening process is completed by basal〈a〉slip of the twin boundary.The strain compatibility between twins is automatically optimized with loading.Moreover,the detwinning mechanism caused by the interaction between twins and basal stacking faults is clarified.
基金supported by the National Key R&D Program of China(Grant No.2022YFE0128300).
文摘The fracture behavior of natural fracture in the geological reservoir subjected to filling property,affects the crack initiation and propagation under stress perturbation.Partial filling flaws were intermediate between open fractures and filled fractures,the fracture response may be worth exploring.In this work,the effect of the filling property of sandstone with partial filling flaws on the fracture behavior was systematically investigated based on three-point bending tests and the numerical approach of discrete element method(DEM).In the laboratory,semi-circular three-point bending tests were carried out with partial filling flaws of various filling strengths.Based on this,numerical simulations were used to further investigate the effect of the filling ratio and the inclination of the partial filling flaw on the mechanical and fracture responses,and the effect of the partial filling flaw under mixed-mode loading on the fracture mechanism was elucidated coupled with acoustic emission(AE)characteristics.The obtained results showed that the increase in filling strength and filling ratio of partial filling flaw led to an increase in peak strength,with a decreasing trend in peak strength with the inclination of partial filling flaw.In terms of crack propagation pattern,the increasing filling strength of the partial filling flaw induced the transformation of the fracture mechanism toward deflection,with a tortuosity path,while the filling ratio and inclination of partial filling flaw led to fracture mechanism change from deflection to penetration and attraction,accompanied with a larger AE event source in filler.Accordingly,the b-value based on the Gutenberg-Richter equation fluctuated between 5 and 4 at low filling ratio and inclination and remained around 5 at high filling ratio and inclination of partial filling flaw.Related results may provide an application prospective for reservoir stimulation using the natural fracture system.
基金supported by the National Natural Science Foundation of China(Nos.42277091 and U22A20578)Xiamen Youth Innovation Fund Project(No.3502Z20206094)+1 种基金Fujian Provincial Environmental Protection Science&Technology Plan Projects(No.2023R004)Xiamen Atmospheric Environment Observation and Research Station of Fujian Province.
文摘Aerosol acidity(pH)plays an important role in the multiphase chemical processes of atmospheric particles.In this study,we demonstrated the seasonal trends of aerosol pH calculated with the ISORROPIA-II model in a coastal city of southeast China.We performed quantitative analysis on the various influencing factors on aerosol pH,and explored the responses of aerosol pH to different PM_(2.5)and O_(3)pollution levels.The results showed that the average aerosol pH was 2.92±0.61,following the order of winter>spring>summer>autumn.Sensitivity tests revealed that SO_(4)^(2−),NH_(x),T and RH triggered the variations of aerosol pH.Quantitative analysis results showed that T(37.9%-51.2%)was the main factors affecting pH variations in four seasons,followed by SO_(4)^(2−)(6.1%-23.7%),NH_(x)(7.2%-22.2%)and RH(0–14.2%).Totally,annual mean meteorological factors(52.9%)and chemical compositions(41.3%)commonly contributed the aerosolpH in the coastal city.The concentrations of PM_(2.5)was positively correlated with aerosol liquid water content(R^(2)=0.53)and aerosol pH(R^(2)=0.26),indicating that the increase in pH was related with the elevated NH_(4)NO_(3)and decreased SO_(4)^(2−),and also the changes of T and RH.The O_(x)(O_(3)+NO_(2))was moderately correlated with aerosol pH(R^(2)=-0.48),attributable to the fact that the proportion of SO_(4)^(2−)increased under high T and low RH conditions.The study strengthened our understanding of the contributions of influencing factors to aerosol pH,and also provided scientific evidences for chemical processes of atmospheric particles in coastal areas.
基金financially supported by the National Natural Science Foundation of China(No.U23A20691)Innovation Group of National Ethnic Affairs Commission of China(No.MZR20006)+2 种基金Fund for Academic Innovation Teams of SouthCentral Minzu University(No.XTZ24012)Fundamental Research Fund for the Central Universities of South-Central Minzu University(Nos.CZD24001 and CZQ25012)Scientific Research Fund of South-Central Minzu University(No.YZY25007)。
文摘The poor degradability and limited recyclability of epoxy resins are key challenges hindering the efficient recycling of ex-service wind turbine blades(EWTBs).Herein,we proposed a selective degradation strategy for direct recycling and high-value recovery of epoxy resins by introducing degradable Schiff base groups into the molecular structure and utilizing the resulting oligomers as curing agents.To realize this strategy,a series of Schiff base compounds were synthesized using bio-based vanillin and diamines and subsequently functionalized with epichlorohydrin to yield bio-based epoxy resins.The cured epoxy resins demonstrated remarkable improvements in the mechanical properties of diglycidyl ether of bisphenol-A(DGEBA),with an increases of 44.49%in the tensile strength of 38.55%,bending strength,and impact strength of 71.20%.The introduction of dynamic Schiff base bonds enabled the selective degradation of the vanillin-2,2-bis[4-(4-aminophenoxy)phenyl]propane-based epoxy resin(VBEP)/DGEBA copolymer,producing 84.20% oligomers that can be directly recycled and reused.Replacing 30 wt% of the curing agent with the oligomer increased the tensile strength of the cured sample to 75.40 MPa,surpassing that of the cured DGEBA.Under simulated acid rain and seawater exposure,the copolymer exhibited a service life of 27 years at 40℃,significantly exceeding the currently reported service life of 20 years.This study presents a sustainable strategy for the direct recycling and high-value reuse of epoxy resin,offering a promising solution for EWTBs.
基金funded by the National Key Research and Development Program of China(Grant No.2023YFC3804205)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Grant No.KYCX24_2706)the Graduate Innovation Program of China University of Mining and Technology(Grant No.2024WLKXJ203).
文摘Massive fracturing fluid injection in reservoir stimulation can alter the fluid pressure field,potentially inducing the faults to slip in an aseismic or seismic phenomenon.In this work,laboratory friction experiments were performed on split-cutting granite fracture to investigate the effect of fluid pressure on injection-induced slip behavior.The injection experiments spanned a fluid pressure range of 1-20 MPa,which was up to half of the confining pressure.The laboratory results demonstrated that an increase in confining pressure led to a marginal reduction in the friction coefficient,decreasing from a range of 0.70-0.80 at 10 MPa to 0.71-0.75 at 40 MPa.Friction constitutive parameters in experiments with fluid pressure above 10 MPa exhibited a transition from velocity-strengthening to velocity-weakening behavior,while remaining consistently velocity-strengthening below this threshold.Similarly,measurements of dilatancy and critical slip distance exhibited a similar evolution,first increasing and then becoming approximately constant,independent of fluid pressure.The observed microstructural evolution of the split-cutting fractures during slip testing supported these mechanical responses.Post-shear slip,a decrease in the fracture roughness and asperity distribution of the split-cutting fracture was noted,with the decrease in amplitude being more pronounced at high confining pressure.Research may provide a prospect on slip-on faults with fluid pressure.
