This study investigates the impacts of mixing time,execution procedure,cement dosage(α),and total water-to-cement ratio(W_(Total)/C)on the mixing energy(E)of deep soil mixing(DSM)columns and how E influences the stre...This study investigates the impacts of mixing time,execution procedure,cement dosage(α),and total water-to-cement ratio(W_(Total)/C)on the mixing energy(E)of deep soil mixing(DSM)columns and how E influences the strength of treated sand.Columns with a diameter of 7.5 cm were constructed using three mixing times(130,190,and 250 s),two execution procedures(normal and zigzag),threeαvalues(300,400,and 500 kg/m^(3)),and three W_(Total)/C ratios(2.5,3.0,and 3.5).For comparison,equivalent laboratory samples were also examined.Results revealed that increasing the mixing time andα,adopting the zigzag execution procedure,and reducing the W_(Total)/C ratio increase E.Outcomes indicated that an increase in E from 0.49-0.70 kJ to 0.70-0.90 kJ,0.90-1.10 kJ,and 1.10-1.40 kJ improves the unconfined compressive strength(UCS)of columns on average by 66%,124%,and 179%,respectively,and the secant modulus by 61%,110%,and 152%.Average strain at maximum stress also rises from 0.68%to 0.75%,0.81%,and 0.84%,respectively.The study identified a threshold in the direct relationship between E and the strength ratio(λ),beyond whichλdid not increase significantly with further increases in E.Additionally,at low and high E levels,DSM samples mainly failed by crushing and cracking modes,respectively.In DSM columns withα=500 kg/m^(3)and W_(Total)/C=2.5,increasing average E from 0.77 kJ to 0.95 kJ,1.08 kJ,and 1.28 kJ resulted in a reduction of coefficients of variation of UCS from 30.4%to 27.8%,24.5%,and 21.1%,respectively.展开更多
The construction of lunar bases represents a crucial goal for long-term human residence on the Moon and future deep-space exploration. Vacuum sintering of lunar regolith for in-situ resource utilization(ISRU) is consi...The construction of lunar bases represents a crucial goal for long-term human residence on the Moon and future deep-space exploration. Vacuum sintering of lunar regolith for in-situ resource utilization(ISRU) is considered one of the most feasible strategies for early lunar infrastructure development. However, the extreme temperature fluctuations on the lunar surface pose potential threats to the structural stability of sintered regolith materials. To investigate the mechanical deterioration and damage mechanism of vacuum-sintered lunar regolith under extreme cryogenic-thermal cycling, lunar regolith simulants are used to fabricate specimens through vacuum sintering. A series of cryogenic-thermal cycling tests is designed, combined with uniaxial compression and X-ray CT scanning, to systematically analyze their macro-micro responses. The results show that with increasing extreme cryogenic-thermal cycles, the stress-strain curves evolve from typical brittle failure to quasiductile behavior, with uniaxial compressive strength and elastic modulus decreasing by approximately 33.86% and 61.98%, respectively. CT analyses reveal that the pore structure transforms from isolated pores to connected networks, with the pore volume fraction increasing from 13.33% to 22.64%, and the fractal dimension increases from 2.465 to 2.544, and stabilizes after multiple cycles. A significant negative correlation(R^(2)> 0.96) exists between pore structural complexity and mechanical performance. Based on these findings, a thermal fatigue damage mechanism dominated by thermal stress concentration due to mismatched thermal expansion coefficients among mineral phases is proposed. This study provides scientific insights for the design, durability evaluation, and ISRU-based construction of lunar surface infrastructure.展开更多
With the continuous increase in performance requirements for power systems in the aerospace and low-altitude economy sectors,designing lightweight and highstrength blade structures with excellent dynamic characteristi...With the continuous increase in performance requirements for power systems in the aerospace and low-altitude economy sectors,designing lightweight and highstrength blade structures with excellent dynamic characteristics has become critical.This paper puts forward a dynamic model for a rotating functionally graded graphenereinforced(FG-GPR)sandwich metal porous cantilever pre-twisted plate(PTP),aiming to analyze its natural vibration characteristics.To this end,the mixture principle and the revised Halpin-Tsai model are used to determine the parameters of graphene and porosity distributions in the core layer.With the classical plate theory,the Rayleigh-Ritz method,and the polynomials,the dynamic equations are derived to solve for the free vibration mode shapes and frequencies of the rotating FG-GPR sandwich metal porous cantilever PTP.The comparison of natural frequencies and mode shapes with available literature results confirms the precision of the theoretical formulation and numerical computations.The bending stiffnesses are analyzed.Finally,the effects of different graphene/pore distributions,length-to-thickness/width ratios,layer thickness ratios,twist angles,and rotational speeds on the natural frequencies of the system are systematically investigated.展开更多
Crack detection accuracy in computer vision is often constrained by limited annotated datasets.Although Generative Adversarial Networks(GANs)have been applied for data augmentation,they frequently introduce blurs and ...Crack detection accuracy in computer vision is often constrained by limited annotated datasets.Although Generative Adversarial Networks(GANs)have been applied for data augmentation,they frequently introduce blurs and artifacts.To address this challenge,this study leverages Denoising Diffusion Probabilistic Models(DDPMs)to generate high-quality synthetic crack images,enriching the training set with diverse and structurally consistent samples that enhance the crack segmentation.The proposed framework involves a two-stage pipeline:first,DDPMs are used to synthesize high-fidelity crack images that capture fine structural details.Second,these generated samples are combined with real data to train segmentation networks,thereby improving accuracy and robustness in crack detection.Compared with GAN-based approaches,DDPM achieved the best fidelity,with the highest Structural Similarity Index(SSIM)(0.302)and lowest Learned Perceptual Image Patch Similarity(LPIPS)(0.461),producing artifact-free images that preserve fine crack details.To validate its effectiveness,six segmentation models were tested,among which LinkNet consistently achieved the best performance,excelling in both region-level accuracy and structural continuity.Incorporating DDPM-augmented data further enhanced segmentation outcomes,increasing F1 scores by up to 1.1%and IoU by 1.7%,while also improving boundary alignment and skeleton continuity compared with models trained on real images alone.Experiments with varying augmentation ratios showed consistent improvements,with F1 rising from 0.946(no augmentation)to 0.957 and IoU from 0.897 to 0.913 at the highest ratio.These findings demonstrate the effectiveness of diffusion-based augmentation for complex crack detection in structural health monitoring.展开更多
Concrete production often relies on natural aggregates,which can lead to resource depletion and environmental harm.In addition,improper disposal of thermoplastic waste exacerbates ecological problems.Although signific...Concrete production often relies on natural aggregates,which can lead to resource depletion and environmental harm.In addition,improper disposal of thermoplastic waste exacerbates ecological problems.Although significant attention has recently been given to recycling various waste materials into concrete,studies specifically addressing thermoplastic recycled aggregates are still trending.This underscores the need to comprehensively review existing literature,identify research trends,and recognize gaps in understanding the mechanical performance of thermoplastic-based recycled aggregate concrete.Accordingly,this review summarizes recent investigations focused on the mechanical properties of thermoplastic-based recycled aggregate concrete,emphasizing aspects such as compressive strength,tensile behavior,modulus of elasticity,and durability characteristics.The primary aim is to consolidate scattered research findings,identify key parameters influencing mechanical behavior,and propose future research directions.Understanding the influence of recycled thermoplastic aggregates on concrete performance significantly supports sustainable construction practices by reducing dependency on virgin aggregates and mitigating environmental impacts associated with waste disposal.In addition,assessing mechanical performance contributes to confidence in the practical application,encouraging the broader adoption of thermoplastic-based recycled aggregate concrete in construction projects.Through this critical synthesis,the review guides researchers and industry practitioners toward informed decisions on the feasibility and reliability of integrating thermoplastic waste into concrete,thereby promoting sustainable infrastructure development.展开更多
The concept of using biological process in soil improvement which is known as bio-mediated soil improvement technique has shown greater potential in geotechnical engineering applications in terms of performance and en...The concept of using biological process in soil improvement which is known as bio-mediated soil improvement technique has shown greater potential in geotechnical engineering applications in terms of performance and environmental sustainability. This paper presents a review on the soil microorganisms responsible for this process, and factors that affect their metabolic activities and geometric compatibility with the soil particle sizes. Two mechanisms of biomineralization, i.e. biologically controlled and biologically induced mineralization, were also discussed. Environmental and other factors that may be encountered in situ during microbially induced calcite precipitation （MICP） and their influences on the process were identified and presented. Improvements in the engineering properties of soil such as strength/stiffness and permeability as evaluated in some studies were explored. Potential applications of the process in geotechnical engineering and the challenges of field application of the process were identified.展开更多
Geographic Information System(GIS)technology is more and more used even in the technical practice of a construction industry.In the preparatory phase of the construction,the problems of a spatial positioning(location)...Geographic Information System(GIS)technology is more and more used even in the technical practice of a construction industry.In the preparatory phase of the construction,the problems of a spatial positioning(location)of the construction have to be solved jointly with the checking of the feasibility and purposefulness,the traffic projects are worked out,and the alternative,more detailed solutions of technical problems are designed.At project development there are used various forms of initial documents,results of the actual data gathering and surveys,map sheets,photographs,previous documents referring to the problems solved,and appropriate legal and technical standards.The article presents the experience with the issue of GIS in construction in preparation of buildings,in the implementation phase of the construction in GIS.It presents a model of information system construction and technology of mobile GIS for data collection and use of mobile GIS in water management.展开更多
Ultrahigh-performance concrete(UHPC)is a groundbreaking kind of concrete that distinguishes itself from conventional concrete through its unique material properties.Understanding and managing the time-dependent charac...Ultrahigh-performance concrete(UHPC)is a groundbreaking kind of concrete that distinguishes itself from conventional concrete through its unique material properties.Understanding and managing the time-dependent characteristics of these materials is essential for their effective use in various construction applications.This study presents an experimental evaluation of the compressive and bending properties of the UHPC incorporating polypropylene,steel,and glass fibers.Based on ACI-211 guidelines,the UHPC mix was designed by using three types of aggregates:limestone,andesite,and quartzite,along with 5%fiber content(at varying percentages of 0,5%,10%,15%,and 20%)relative to the cementitious materials,and three different water-to-cement(w/c)ratios(0.24,0.3,and 0.4)were used.In this research,the compressive and flexural strength tests were conducted.The results show that increasing the values of the fibers significantly enhances the compressive strength of the studied samples.Furthermore,the utilization of fibers markedly improves the bending strength of the samples,demonstrating a strong correlation with the yield resistance of the material.Also,findings show that using steel fibers increases the compressive and bending strength of the tested samples more than polypropylene and glass fibers.For instance,in UHPC samples with 0.4 w/c,the average compressive strength values are 82.2 MPa,70.3 MPa,and 67.1 MPa for steel,polypropylene,and glass fibers,respectively.Also,in the flexural strength test,the modulus of rupture is obtained as an average of 6.24 MPa,5.24 MPa and 4.83 MPa for UHPC samples with steel,polypropylene and glass fibers,respectively.展开更多
The constant amplitude loading fatigue tests were carried out on the 6061/7075 aluminum alloy TIG fillet welded lap specimens in this study,and the weld seam cross-section hardness was measured.The experimental result...The constant amplitude loading fatigue tests were carried out on the 6061/7075 aluminum alloy TIG fillet welded lap specimens in this study,and the weld seam cross-section hardness was measured.The experimental results show that most specimens mainly failed at the 7075 side weld toes even though the base material tensile strength of 7075 is higher than that of 6061.The maximum stress-strain concentration in the two finite element models is located at the 7075 side weld toe,which is basically consistent with the actual fracture location.The weld zone on the 7075 side experiences severe material softening,with a large gradient.However,the Vickers hardness value on the 6061 side negligibly changes and fluctuates around 70 HV.No obvious defects are found on the fatigue fracture,but a large number of secondary cracks appear.Cracks germinate from the weld toe and propagate in the direction of the plate thickness.Weld reinforcement has a serious impact on fatigue life.Fatigue life will decrease exponentially as the weld reinforcement increases under low stress.It is found that the notch stress method can give a better fatigue life prediction for TIG weldments,and the errors of the predicted results are within the range of two factors,while the prediction accuracy decreases under low stress.The equivalent structural stress method can also be used for fatigue life prediction of TIG weldments,but the errors of prediction results are within the range of three factors,and the accuracy decreases under high stress.展开更多
Treatment of peat soil foundation in Yunnan surrounding Dianchi and Erhai Lakes poses complex problems for engineering projects.It is insufficient to rely on ordinary cement to reinforce peat soil.In order to make the...Treatment of peat soil foundation in Yunnan surrounding Dianchi and Erhai Lakes poses complex problems for engineering projects.It is insufficient to rely on ordinary cement to reinforce peat soil.In order to make the reinforcement reliable,this experiment mixed(ultrafine cement)UFC into ordinary cement to form a composite solidify agent.This study aimed to analyze the influence of UFC proportion on the strength of cement-soil in the peat soil environment.Unconfined compressive strength(UCS)and scanning electron microscope(SEM)tests were conducted on samples soaked for 28 and 90 days,respectively.The test results show that without considering the effects of Humic Acid(HA)and Fulvic Acid(FA),incorporating UFC can significantly improve the UCS of cement-soil.The rapid hydration of the fine particles generates a large number of cementitious products,improves the cohesion of the soil skeleton,and fills the pores.However,when the proportion of UFC increases,the aggregate structure formed by a larger quantity of fine particles reduces the hydration rate and degree of cement hydration,making the UCS growth rate of cement-soil insignificant.In the peat soil environment,HA significantly weakened the UCS of cement-soil in both physical and chemical aspects.However,UFC can mitigate the adverse effect of HA on cement-soil by its small particle size,high surface energy,and solid binding ability.In addition,FA has a positive effect on the UCS of cement-soil soaked for 28 days and 90 days.The UFC addition could promote the enhancement effect of FA on cement-soil UCS.SEM test results showed that cement hydration products increased significantly with the increase of UFC proportion,and cementation between hydration products and soil particles was enhanced.The size and connectivity of cement-soil pores were significantly reduced,thereby improving cement-soil structural integrity.展开更多
The present study investigates the engineering properties of submerged organic silt(orSi)stabilized with F-class fly ash(FA),with and without the addition of an activator(CaO).The utilization of F-class FA for soil im...The present study investigates the engineering properties of submerged organic silt(orSi)stabilized with F-class fly ash(FA),with and without the addition of an activator(CaO).The utilization of F-class FA for soil improvement is an important aspect of sustainable and environmentally-conscious geotechnical engineering when marginal usage of lime and concrete is of great interest to engineers and societies.Currently,discussion is predominantly focused on the positive aspects of using the F-class FA,with a paucity of emphasis on the negative aspects.To explore these features more thoroughly,a series of strength and compressibility tests was conducted.The sample preparation and curing methodology were chosen to replicate the in situ conditions where soil is surcharged and submerged in water.It was found that the incorporation of F-class FA without an activator reduces the undrained shear strength of submerged orSi by about 20%–25%and permanently prevents any thixotropic strength restoration.An increase in undrained shear strength is observed when lime(3%–6%)is added to the soil–FA mixture or when only lime(in the same amount of 3%–6%)is used.Consequently,F-class FA can be successfully used as a filler for slurries with minimum lime content in soil mixing methods.The F-class FA(with or without an activator)shifts the so-called“creep delay”in time,consequently reducing the total creep settlements.The shift of“creep delay”is more considerable for orSi stabilized with lime or with FA and lime as an activator,than for orSi stabilized with pure F-class FA.展开更多
Interest in understanding the structural behavior of marine floating photovoltaic(FPV)systems has grown significantly over the last decade.Numerical models are the preferred approach for understanding FPV responses un...Interest in understanding the structural behavior of marine floating photovoltaic(FPV)systems has grown significantly over the last decade.Numerical models are the preferred approach for understanding FPV responses under environmental loads,but they require validation.Several methods are commonly used to validate numerical results,such as comparison with analytical,field data,and experimental data.The use of analytical approaches to validate numerical results can sometimes be inaccurate due to the complexity of the problems;nevertheless,field data is commonly restricted and frequently unavailable for numerical model validation.Thus,physical models play a crucial role in validating numerical results.This study focuses on the two-dimensional(2-D)modeling process and sensors development for an FPV system with taut mooring,aiming to investigate wave-structure interaction while considering hydroelastic effects.The model is developed in accordance with the Froude-Cauchy similitude law and is made from composite materials to capture structural stiffness.Structural motions,specifically heave and pitch,are measured using an Inertial Measurement Unit(IMU),while strain gauges measure structural stress and mooring tension.The sensors provide precise measurements for strain and pitch;however,heave,as a result of time-domain integration from acceleration,requires further validation.The motion responses of the model align with reference results.展开更多
The antlions dig a conical simple pit in sand to catch ants.The funnel shape of the trap is deliberate with a critical angle of repose and is steep and shallow enough to trigger avalanches and cause struggling prey to...The antlions dig a conical simple pit in sand to catch ants.The funnel shape of the trap is deliberate with a critical angle of repose and is steep and shallow enough to trigger avalanches and cause struggling prey to fall into the funnel.The trap should be designed by optimizing pit morphology according to natural selection.In the current study,antlion behavior and pit morphology in the sand samples with different particle shapes and particle size distributions were studied.The small larvae build in fine sand and silty sand,while larger ones prefer fine to medium sands.However,there is no preference for sands with different particle shapes.Further,the static and dynamic angles of repose for the sand samples were measured,and the slope of the pits was compared with the repose angles.The angle of the heap slope oscillated between an upper angle or angle of sliding(the angle that triggers a landslide)and a lower angle named repose angle.展开更多
Squeezing phenomena can lead to severe loads in deep tunnels,especially in the presence of a low ratio of surrounding rock strength to overburden pressure.For this reason,it is highly imperative to analyze and identif...Squeezing phenomena can lead to severe loads in deep tunnels,especially in the presence of a low ratio of surrounding rock strength to overburden pressure.For this reason,it is highly imperative to analyze and identify a suitable methodology to estimate the squeezing potential and select a proper support system of rock mass.This study aims to reveal the causes of failure of Tishreen tunnel in the west of Syria and develop remediation measures accordingly so as to bring the tunnel back into service.The tunnel in question was subjected to successive failures such as buckling and spalling of side walls,floor heave,and extremely large convergence reaching the failure state of the tunnel lining.In this study,an effective way was demonstrated to evaluate the squeezing potential of the tunnel lining and appropriate modeling of the long-term response of a tunnel excavated in weak rock.Specifically,the causes of failure of Tishreen tunnel were first evaluated by empirical approaches.Then,a numerical model was developed using a timedependent constitutive model to investigate the time-dependent response of the tunnel lining.On this basis,this study proposed an effective reinforcement schemes including steel ribs,grout injection,ground anchors,and new lining of reinforced concrete.The results show that the Burger viscoplastic model simulates effectively the resulting deformation and creep behavior of squeezing ground.It is also observed that using a combined heavy support system can provide efficient control over squeezing deformation and maintain the serviceability of the tunnel under study.展开更多
Fine debris is an important component of natural debris flows.Previous studies focused primarily on the clay minerals found in the fines,and non-clay minerals were often neglected.The effects of mineralogy of fines on...Fine debris is an important component of natural debris flows.Previous studies focused primarily on the clay minerals found in the fines,and non-clay minerals were often neglected.The effects of mineralogy of fines on debris-mass slurrying and flow behaviors of the resultant slurries are examined herein.The fines(≤0.04 mm)in the<5 mm fraction of the Dongyuege Creek debris-flow deposit is replaced with five other mineral powders with the same maximum particle size.Four types of separate and sequential experiments related to debris slurrying and slurry behaviors are carried out with the prepared clastic materials.The obtained slurrying index ranging from 0.08 to 0.18 shows that non-clay minerals also can function as the fine fractions of debris-flow materials,so long as the requirement of grain size distribution is met.Equidimensional,non-clay minerals making up fines of debris flows can increase the upper solid concentration limits of slurrying(with a maximum of 0.692)and peak values of relative excess water pressure(measured maximum mean peak value is 0.99),leading to higher momentum and higher competence,and thereby more destructive catastrophe.The sediments with platy non-clay mineral-dominated fines have potential for mobilizing into small-to medium-size debris flows with a relatively small competence.Clay minerals in the fines may indeed enhance the liquefaction potential of debris masses by expanding the difference between upper and lower solid concentration limits of slurrying(0.413 and 0.238,respectively,for pure kaolinite),but they significantly suppress the momentum,competence,and destructive power of potential debris flows by lowering upper solid concentration limit of slurrying of debris masses.Alpine catchments rich in non-clay minerals,notably those releasing dolomite into loose sediments,may be more prone to threatening and destructive debris flows.The basin producing clay minerals should be more susceptible to lowmagnitude/high-frequency debris flows with less devastating consequences.展开更多
The study presents the results of over 30,000 numerical analyses on the stability of lava tubes under lunar conditions.The research considered random irregularities in cave geometry and their impact on stability,with ...The study presents the results of over 30,000 numerical analyses on the stability of lava tubes under lunar conditions.The research considered random irregularities in cave geometry and their impact on stability,with a particular focus on the geometric characteristics of identified collapses.We propose a procedure for extracting the collapse areas and integrating it into the stability analysis results.The results were examined to assess the possibility of describing the geometry characteristics of collapses using commonly applied probability density distributions,such as normal or lognormal distribution.Our aim is to facilitate future risk assessment of lunar caves.Such an assessment will be essential prior to robotically exploring caves beneath the lunar surface and can be extended to be used for planetary caves beyond the Moon.Our findings indicate that several collapse characteristics can be represented by unimodal probability density distributions,which could significantly simplify the candidate selection process.Based on our results,we also highlight several key directions for future research and suggested implications related to their future exploration.展开更多
A robust generalized continuum model called the wavelength-dependent strain gradient continuum model(WDSGM)has been proposed to predict dispersion properties of two-dimensional(2D)periodic lattice metamaterials.The ke...A robust generalized continuum model called the wavelength-dependent strain gradient continuum model(WDSGM)has been proposed to predict dispersion properties of two-dimensional(2D)periodic lattice metamaterials.The key idea lies in replacing the classical Taylor expansion of displacement fields with a wavelength-dependent one,naturally leading to new equations of motion and therefore a significantly improved capability of predicting dispersion characteristics.For different 2D lattices,dispersion results derived from the proposed WDSGM are verified by comparing with those obtained from the discrete model and the existing strain gradient continuum model(SGM)in the irreducible Brillouin zone.Based on the proposed model,the effects of SG orders have been investigated.Results suggest that considering the wavelength-dependent Taylor expansion and increasing the SG order are beneficial to improving the predictive performance of continuum models.The proposed model is free of any instability issue which is challenging for many existing SG methods.Under given parameters,the proposed WDSGM with eighth-order truncation is enough to predict the dispersion relation of three lattices,i.e.,the square,triangular and hexagonal lattices throughout the irreducible Brillouin zone.展开更多
As prestressed concrete(PC)structures age,long-termeffects,e.g.,creep,shrinkage,and prestress losses,compromise their structural performance.Strengthening these aged PC beams has become a crucial matter.One effective ...As prestressed concrete(PC)structures age,long-termeffects,e.g.,creep,shrinkage,and prestress losses,compromise their structural performance.Strengthening these aged PC beams has become a crucial matter.One effective solution is to use externally bonded fiber-reinforced polymer(FRP)sheets;however,limited research has been done on aged PC beams using the FRP,especially for beams with unbonded prestressing strands(UPC beams).Therefore,this research investigates the flexural strengthening efficacy of external FRP sheets on aged UPC beams with unbonded tendons.Aging minimally affected the failure modes of UPC beams,with nonstrengthened beams showing flexural failure via rebar yielding and concrete crushing,and FRP-strengthened beams failing due to FRP debonding and tensile reinforcement yielding,though tendons in the aged beams did not yield due to prestress losses,unlike the new beams.The U-wrap anchor curbed widespread debonding,leading to tensile reinforcement yielding and FRP rupture.Aging hastened crack growth and stiffness loss,increasing deflections and reducing load resistance,but FRP reinforcement mitigated these effects,enhancing cracking resistance by 14%over the unstrengthened aged beams and 7%over the new beams while boosting ultimate resistance by 9%above the non-strengthened new beams.Compared to the new FRP-strengthened beams,the aged counterparts had lower cracking resistance,stiffness and capacity—showing 20%higher deflections,7–9%lower serviceability loads,7%–17%reduced ultimate strength and 17%less deformability—due to prestress losses and premature FRP debonding.展开更多
Active holes outperform photoelectron-mediated oxygen reduction in degrading recalcitrant organics under anaerobic conditions,yet their utilization is limited by rapid charge recombination.This challenge was addressed...Active holes outperform photoelectron-mediated oxygen reduction in degrading recalcitrant organics under anaerobic conditions,yet their utilization is limited by rapid charge recombination.This challenge was addressed through Cu-based yolk-double-shell microspheres(Cu/Cu_(2)O@C-2shell)engineered via heterogeneous contraction and reduction strategies.Work function analyses confirm Schottky junction-driven electron transfer from Cu_(2)O to Cu,generating an internal electric field that suppresses backflow.Density functional theory reveals Cu-mediated enhancement of near-Fermi states(Cu 3d orbitals)and a directional Cu_(2)O→Cu→C electron pathway,spatially isolating holes in Cu_(2)O.Finite-difference time-domain simulations reveal light-induced electric field gradients in the dual-shell architecture:Cu^(0)-mediated localized surface plasmon resonance effect enhances surface field concentration,while hierarchical interfaces create an outward-to-inward gradient,directing electron migration inward and stabilizing oxidative holes at the surface.The optimized(Cu/Cu_(2)O)@C-2shell exhibits 38-fold higher tetracycline degradation under sunlight versus benchmarks,with treated water supporting Escherichia coli survival and wheat growth.This study provides a design strategy for the accumulation of long-lived holes on semiconductor photocatalysts.展开更多
The effect of using 2%and 10%sodium hydroxide solution as surface treatment of rape straw on its water vapor adsorption properties is analyzed in the relative humidity(RH)range of 0%to 98%.Scanning electron microscopy...The effect of using 2%and 10%sodium hydroxide solution as surface treatment of rape straw on its water vapor adsorption properties is analyzed in the relative humidity(RH)range of 0%to 98%.Scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and Fourier-transform infrared spectroscopy(FTIR)are used to investigate the morphological,chemical and structural changes of the treated straw surface.The mineral particles formed on the surface after the treatment are analyzed using X-ray diffraction(XRD).The application of sodium hydroxide solution results in the disruption of the straw surface.As the concentration of sodium hydroxide increases,the disruption of the straw surface increases,and the ability of the straw to adsorb water vapor also increases over the entire RH range.In addition to the surface disruption and chemical changes caused by the alkaline treatment,the differences in the equilibrium moisture content of treated and untreated rape straw can also be attributed to the formation of minerals on the straw surface,namely calcite for the 2%sodium hydroxide solution,and gaylussite and thermonatrite for the 10%solution.展开更多
文摘This study investigates the impacts of mixing time,execution procedure,cement dosage(α),and total water-to-cement ratio(W_(Total)/C)on the mixing energy(E)of deep soil mixing(DSM)columns and how E influences the strength of treated sand.Columns with a diameter of 7.5 cm were constructed using three mixing times(130,190,and 250 s),two execution procedures(normal and zigzag),threeαvalues(300,400,and 500 kg/m^(3)),and three W_(Total)/C ratios(2.5,3.0,and 3.5).For comparison,equivalent laboratory samples were also examined.Results revealed that increasing the mixing time andα,adopting the zigzag execution procedure,and reducing the W_(Total)/C ratio increase E.Outcomes indicated that an increase in E from 0.49-0.70 kJ to 0.70-0.90 kJ,0.90-1.10 kJ,and 1.10-1.40 kJ improves the unconfined compressive strength(UCS)of columns on average by 66%,124%,and 179%,respectively,and the secant modulus by 61%,110%,and 152%.Average strain at maximum stress also rises from 0.68%to 0.75%,0.81%,and 0.84%,respectively.The study identified a threshold in the direct relationship between E and the strength ratio(λ),beyond whichλdid not increase significantly with further increases in E.Additionally,at low and high E levels,DSM samples mainly failed by crushing and cracking modes,respectively.In DSM columns withα=500 kg/m^(3)and W_(Total)/C=2.5,increasing average E from 0.77 kJ to 0.95 kJ,1.08 kJ,and 1.28 kJ resulted in a reduction of coefficients of variation of UCS from 30.4%to 27.8%,24.5%,and 21.1%,respectively.
基金supported by the National Natural Science Foundation of China (Grant Nos.U23A6018,42362034)the Applied Basic Research Foundation of Yunnan Province,China (Grant No.202401AS070068)。
文摘The construction of lunar bases represents a crucial goal for long-term human residence on the Moon and future deep-space exploration. Vacuum sintering of lunar regolith for in-situ resource utilization(ISRU) is considered one of the most feasible strategies for early lunar infrastructure development. However, the extreme temperature fluctuations on the lunar surface pose potential threats to the structural stability of sintered regolith materials. To investigate the mechanical deterioration and damage mechanism of vacuum-sintered lunar regolith under extreme cryogenic-thermal cycling, lunar regolith simulants are used to fabricate specimens through vacuum sintering. A series of cryogenic-thermal cycling tests is designed, combined with uniaxial compression and X-ray CT scanning, to systematically analyze their macro-micro responses. The results show that with increasing extreme cryogenic-thermal cycles, the stress-strain curves evolve from typical brittle failure to quasiductile behavior, with uniaxial compressive strength and elastic modulus decreasing by approximately 33.86% and 61.98%, respectively. CT analyses reveal that the pore structure transforms from isolated pores to connected networks, with the pore volume fraction increasing from 13.33% to 22.64%, and the fractal dimension increases from 2.465 to 2.544, and stabilizes after multiple cycles. A significant negative correlation(R^(2)> 0.96) exists between pore structural complexity and mechanical performance. Based on these findings, a thermal fatigue damage mechanism dominated by thermal stress concentration due to mismatched thermal expansion coefficients among mineral phases is proposed. This study provides scientific insights for the design, durability evaluation, and ISRU-based construction of lunar surface infrastructure.
基金Project supported by the National Natural Science Foundation of China(Nos.12272056 and 11832002)。
文摘With the continuous increase in performance requirements for power systems in the aerospace and low-altitude economy sectors,designing lightweight and highstrength blade structures with excellent dynamic characteristics has become critical.This paper puts forward a dynamic model for a rotating functionally graded graphenereinforced(FG-GPR)sandwich metal porous cantilever pre-twisted plate(PTP),aiming to analyze its natural vibration characteristics.To this end,the mixture principle and the revised Halpin-Tsai model are used to determine the parameters of graphene and porosity distributions in the core layer.With the classical plate theory,the Rayleigh-Ritz method,and the polynomials,the dynamic equations are derived to solve for the free vibration mode shapes and frequencies of the rotating FG-GPR sandwich metal porous cantilever PTP.The comparison of natural frequencies and mode shapes with available literature results confirms the precision of the theoretical formulation and numerical computations.The bending stiffnesses are analyzed.Finally,the effects of different graphene/pore distributions,length-to-thickness/width ratios,layer thickness ratios,twist angles,and rotational speeds on the natural frequencies of the system are systematically investigated.
基金the National Natural Science Foundation of China(Grant No.:52508343)the Fundamental Research Funds for the Central Universities(Grant No.:B250201004).
文摘Crack detection accuracy in computer vision is often constrained by limited annotated datasets.Although Generative Adversarial Networks(GANs)have been applied for data augmentation,they frequently introduce blurs and artifacts.To address this challenge,this study leverages Denoising Diffusion Probabilistic Models(DDPMs)to generate high-quality synthetic crack images,enriching the training set with diverse and structurally consistent samples that enhance the crack segmentation.The proposed framework involves a two-stage pipeline:first,DDPMs are used to synthesize high-fidelity crack images that capture fine structural details.Second,these generated samples are combined with real data to train segmentation networks,thereby improving accuracy and robustness in crack detection.Compared with GAN-based approaches,DDPM achieved the best fidelity,with the highest Structural Similarity Index(SSIM)(0.302)and lowest Learned Perceptual Image Patch Similarity(LPIPS)(0.461),producing artifact-free images that preserve fine crack details.To validate its effectiveness,six segmentation models were tested,among which LinkNet consistently achieved the best performance,excelling in both region-level accuracy and structural continuity.Incorporating DDPM-augmented data further enhanced segmentation outcomes,increasing F1 scores by up to 1.1%and IoU by 1.7%,while also improving boundary alignment and skeleton continuity compared with models trained on real images alone.Experiments with varying augmentation ratios showed consistent improvements,with F1 rising from 0.946(no augmentation)to 0.957 and IoU from 0.897 to 0.913 at the highest ratio.These findings demonstrate the effectiveness of diffusion-based augmentation for complex crack detection in structural health monitoring.
文摘Concrete production often relies on natural aggregates,which can lead to resource depletion and environmental harm.In addition,improper disposal of thermoplastic waste exacerbates ecological problems.Although significant attention has recently been given to recycling various waste materials into concrete,studies specifically addressing thermoplastic recycled aggregates are still trending.This underscores the need to comprehensively review existing literature,identify research trends,and recognize gaps in understanding the mechanical performance of thermoplastic-based recycled aggregate concrete.Accordingly,this review summarizes recent investigations focused on the mechanical properties of thermoplastic-based recycled aggregate concrete,emphasizing aspects such as compressive strength,tensile behavior,modulus of elasticity,and durability characteristics.The primary aim is to consolidate scattered research findings,identify key parameters influencing mechanical behavior,and propose future research directions.Understanding the influence of recycled thermoplastic aggregates on concrete performance significantly supports sustainable construction practices by reducing dependency on virgin aggregates and mitigating environmental impacts associated with waste disposal.In addition,assessing mechanical performance contributes to confidence in the practical application,encouraging the broader adoption of thermoplastic-based recycled aggregate concrete in construction projects.Through this critical synthesis,the review guides researchers and industry practitioners toward informed decisions on the feasibility and reliability of integrating thermoplastic waste into concrete,thereby promoting sustainable infrastructure development.
文摘The concept of using biological process in soil improvement which is known as bio-mediated soil improvement technique has shown greater potential in geotechnical engineering applications in terms of performance and environmental sustainability. This paper presents a review on the soil microorganisms responsible for this process, and factors that affect their metabolic activities and geometric compatibility with the soil particle sizes. Two mechanisms of biomineralization, i.e. biologically controlled and biologically induced mineralization, were also discussed. Environmental and other factors that may be encountered in situ during microbially induced calcite precipitation （MICP） and their influences on the process were identified and presented. Improvements in the engineering properties of soil such as strength/stiffness and permeability as evaluated in some studies were explored. Potential applications of the process in geotechnical engineering and the challenges of field application of the process were identified.
基金support of research task of M inistry of Education No.00216630519.
文摘Geographic Information System(GIS)technology is more and more used even in the technical practice of a construction industry.In the preparatory phase of the construction,the problems of a spatial positioning(location)of the construction have to be solved jointly with the checking of the feasibility and purposefulness,the traffic projects are worked out,and the alternative,more detailed solutions of technical problems are designed.At project development there are used various forms of initial documents,results of the actual data gathering and surveys,map sheets,photographs,previous documents referring to the problems solved,and appropriate legal and technical standards.The article presents the experience with the issue of GIS in construction in preparation of buildings,in the implementation phase of the construction in GIS.It presents a model of information system construction and technology of mobile GIS for data collection and use of mobile GIS in water management.
文摘Ultrahigh-performance concrete(UHPC)is a groundbreaking kind of concrete that distinguishes itself from conventional concrete through its unique material properties.Understanding and managing the time-dependent characteristics of these materials is essential for their effective use in various construction applications.This study presents an experimental evaluation of the compressive and bending properties of the UHPC incorporating polypropylene,steel,and glass fibers.Based on ACI-211 guidelines,the UHPC mix was designed by using three types of aggregates:limestone,andesite,and quartzite,along with 5%fiber content(at varying percentages of 0,5%,10%,15%,and 20%)relative to the cementitious materials,and three different water-to-cement(w/c)ratios(0.24,0.3,and 0.4)were used.In this research,the compressive and flexural strength tests were conducted.The results show that increasing the values of the fibers significantly enhances the compressive strength of the studied samples.Furthermore,the utilization of fibers markedly improves the bending strength of the samples,demonstrating a strong correlation with the yield resistance of the material.Also,findings show that using steel fibers increases the compressive and bending strength of the tested samples more than polypropylene and glass fibers.For instance,in UHPC samples with 0.4 w/c,the average compressive strength values are 82.2 MPa,70.3 MPa,and 67.1 MPa for steel,polypropylene,and glass fibers,respectively.Also,in the flexural strength test,the modulus of rupture is obtained as an average of 6.24 MPa,5.24 MPa and 4.83 MPa for UHPC samples with steel,polypropylene and glass fibers,respectively.
基金Partially funded by the National Natural Science Foundation of China(No.51065012)。
文摘The constant amplitude loading fatigue tests were carried out on the 6061/7075 aluminum alloy TIG fillet welded lap specimens in this study,and the weld seam cross-section hardness was measured.The experimental results show that most specimens mainly failed at the 7075 side weld toes even though the base material tensile strength of 7075 is higher than that of 6061.The maximum stress-strain concentration in the two finite element models is located at the 7075 side weld toe,which is basically consistent with the actual fracture location.The weld zone on the 7075 side experiences severe material softening,with a large gradient.However,the Vickers hardness value on the 6061 side negligibly changes and fluctuates around 70 HV.No obvious defects are found on the fatigue fracture,but a large number of secondary cracks appear.Cracks germinate from the weld toe and propagate in the direction of the plate thickness.Weld reinforcement has a serious impact on fatigue life.Fatigue life will decrease exponentially as the weld reinforcement increases under low stress.It is found that the notch stress method can give a better fatigue life prediction for TIG weldments,and the errors of the predicted results are within the range of two factors,while the prediction accuracy decreases under low stress.The equivalent structural stress method can also be used for fatigue life prediction of TIG weldments,but the errors of prediction results are within the range of three factors,and the accuracy decreases under high stress.
基金National Natural Science Foundation of China(No.41967035)。
文摘Treatment of peat soil foundation in Yunnan surrounding Dianchi and Erhai Lakes poses complex problems for engineering projects.It is insufficient to rely on ordinary cement to reinforce peat soil.In order to make the reinforcement reliable,this experiment mixed(ultrafine cement)UFC into ordinary cement to form a composite solidify agent.This study aimed to analyze the influence of UFC proportion on the strength of cement-soil in the peat soil environment.Unconfined compressive strength(UCS)and scanning electron microscope(SEM)tests were conducted on samples soaked for 28 and 90 days,respectively.The test results show that without considering the effects of Humic Acid(HA)and Fulvic Acid(FA),incorporating UFC can significantly improve the UCS of cement-soil.The rapid hydration of the fine particles generates a large number of cementitious products,improves the cohesion of the soil skeleton,and fills the pores.However,when the proportion of UFC increases,the aggregate structure formed by a larger quantity of fine particles reduces the hydration rate and degree of cement hydration,making the UCS growth rate of cement-soil insignificant.In the peat soil environment,HA significantly weakened the UCS of cement-soil in both physical and chemical aspects.However,UFC can mitigate the adverse effect of HA on cement-soil by its small particle size,high surface energy,and solid binding ability.In addition,FA has a positive effect on the UCS of cement-soil soaked for 28 days and 90 days.The UFC addition could promote the enhancement effect of FA on cement-soil UCS.SEM test results showed that cement hydration products increased significantly with the increase of UFC proportion,and cementation between hydration products and soil particles was enhanced.The size and connectivity of cement-soil pores were significantly reduced,thereby improving cement-soil structural integrity.
基金supported by the Polish National Science Center(Grant No.2022/06/X/ST10/00320)received by Witold Tisler.
文摘The present study investigates the engineering properties of submerged organic silt(orSi)stabilized with F-class fly ash(FA),with and without the addition of an activator(CaO).The utilization of F-class FA for soil improvement is an important aspect of sustainable and environmentally-conscious geotechnical engineering when marginal usage of lime and concrete is of great interest to engineers and societies.Currently,discussion is predominantly focused on the positive aspects of using the F-class FA,with a paucity of emphasis on the negative aspects.To explore these features more thoroughly,a series of strength and compressibility tests was conducted.The sample preparation and curing methodology were chosen to replicate the in situ conditions where soil is surcharged and submerged in water.It was found that the incorporation of F-class FA without an activator reduces the undrained shear strength of submerged orSi by about 20%–25%and permanently prevents any thixotropic strength restoration.An increase in undrained shear strength is observed when lime(3%–6%)is added to the soil–FA mixture or when only lime(in the same amount of 3%–6%)is used.Consequently,F-class FA can be successfully used as a filler for slurries with minimum lime content in soil mixing methods.The F-class FA(with or without an activator)shifts the so-called“creep delay”in time,consequently reducing the total creep settlements.The shift of“creep delay”is more considerable for orSi stabilized with lime or with FA and lime as an activator,than for orSi stabilized with pure F-class FA.
基金funded by the Center for Higher Education Funding and Assessment(Pusat Pelayanan Pembiayaan dan Asesmen Pendidkan Tinggi)-Ministry of Higher Education,Science,and Technology of Republic Indonesia.
文摘Interest in understanding the structural behavior of marine floating photovoltaic(FPV)systems has grown significantly over the last decade.Numerical models are the preferred approach for understanding FPV responses under environmental loads,but they require validation.Several methods are commonly used to validate numerical results,such as comparison with analytical,field data,and experimental data.The use of analytical approaches to validate numerical results can sometimes be inaccurate due to the complexity of the problems;nevertheless,field data is commonly restricted and frequently unavailable for numerical model validation.Thus,physical models play a crucial role in validating numerical results.This study focuses on the two-dimensional(2-D)modeling process and sensors development for an FPV system with taut mooring,aiming to investigate wave-structure interaction while considering hydroelastic effects.The model is developed in accordance with the Froude-Cauchy similitude law and is made from composite materials to capture structural stiffness.Structural motions,specifically heave and pitch,are measured using an Inertial Measurement Unit(IMU),while strain gauges measure structural stress and mooring tension.The sensors provide precise measurements for strain and pitch;however,heave,as a result of time-domain integration from acceleration,requires further validation.The motion responses of the model align with reference results.
文摘The antlions dig a conical simple pit in sand to catch ants.The funnel shape of the trap is deliberate with a critical angle of repose and is steep and shallow enough to trigger avalanches and cause struggling prey to fall into the funnel.The trap should be designed by optimizing pit morphology according to natural selection.In the current study,antlion behavior and pit morphology in the sand samples with different particle shapes and particle size distributions were studied.The small larvae build in fine sand and silty sand,while larger ones prefer fine to medium sands.However,there is no preference for sands with different particle shapes.Further,the static and dynamic angles of repose for the sand samples were measured,and the slope of the pits was compared with the repose angles.The angle of the heap slope oscillated between an upper angle or angle of sliding(the angle that triggers a landslide)and a lower angle named repose angle.
文摘Squeezing phenomena can lead to severe loads in deep tunnels,especially in the presence of a low ratio of surrounding rock strength to overburden pressure.For this reason,it is highly imperative to analyze and identify a suitable methodology to estimate the squeezing potential and select a proper support system of rock mass.This study aims to reveal the causes of failure of Tishreen tunnel in the west of Syria and develop remediation measures accordingly so as to bring the tunnel back into service.The tunnel in question was subjected to successive failures such as buckling and spalling of side walls,floor heave,and extremely large convergence reaching the failure state of the tunnel lining.In this study,an effective way was demonstrated to evaluate the squeezing potential of the tunnel lining and appropriate modeling of the long-term response of a tunnel excavated in weak rock.Specifically,the causes of failure of Tishreen tunnel were first evaluated by empirical approaches.Then,a numerical model was developed using a timedependent constitutive model to investigate the time-dependent response of the tunnel lining.On this basis,this study proposed an effective reinforcement schemes including steel ribs,grout injection,ground anchors,and new lining of reinforced concrete.The results show that the Burger viscoplastic model simulates effectively the resulting deformation and creep behavior of squeezing ground.It is also observed that using a combined heavy support system can provide efficient control over squeezing deformation and maintain the serviceability of the tunnel under study.
基金supported by the National Natural Science Foundation of China(41931294)the National Natural Science Foundation of China-Yunnan Joint Fund(U1502232,U1033601)。
文摘Fine debris is an important component of natural debris flows.Previous studies focused primarily on the clay minerals found in the fines,and non-clay minerals were often neglected.The effects of mineralogy of fines on debris-mass slurrying and flow behaviors of the resultant slurries are examined herein.The fines(≤0.04 mm)in the<5 mm fraction of the Dongyuege Creek debris-flow deposit is replaced with five other mineral powders with the same maximum particle size.Four types of separate and sequential experiments related to debris slurrying and slurry behaviors are carried out with the prepared clastic materials.The obtained slurrying index ranging from 0.08 to 0.18 shows that non-clay minerals also can function as the fine fractions of debris-flow materials,so long as the requirement of grain size distribution is met.Equidimensional,non-clay minerals making up fines of debris flows can increase the upper solid concentration limits of slurrying(with a maximum of 0.692)and peak values of relative excess water pressure(measured maximum mean peak value is 0.99),leading to higher momentum and higher competence,and thereby more destructive catastrophe.The sediments with platy non-clay mineral-dominated fines have potential for mobilizing into small-to medium-size debris flows with a relatively small competence.Clay minerals in the fines may indeed enhance the liquefaction potential of debris masses by expanding the difference between upper and lower solid concentration limits of slurrying(0.413 and 0.238,respectively,for pure kaolinite),but they significantly suppress the momentum,competence,and destructive power of potential debris flows by lowering upper solid concentration limit of slurrying of debris masses.Alpine catchments rich in non-clay minerals,notably those releasing dolomite into loose sediments,may be more prone to threatening and destructive debris flows.The basin producing clay minerals should be more susceptible to lowmagnitude/high-frequency debris flows with less devastating consequences.
基金The work was performed based on the research project no.2023/51/D/ST10/01956,financed by the National Science Center,Poland.
文摘The study presents the results of over 30,000 numerical analyses on the stability of lava tubes under lunar conditions.The research considered random irregularities in cave geometry and their impact on stability,with a particular focus on the geometric characteristics of identified collapses.We propose a procedure for extracting the collapse areas and integrating it into the stability analysis results.The results were examined to assess the possibility of describing the geometry characteristics of collapses using commonly applied probability density distributions,such as normal or lognormal distribution.Our aim is to facilitate future risk assessment of lunar caves.Such an assessment will be essential prior to robotically exploring caves beneath the lunar surface and can be extended to be used for planetary caves beyond the Moon.Our findings indicate that several collapse characteristics can be represented by unimodal probability density distributions,which could significantly simplify the candidate selection process.Based on our results,we also highlight several key directions for future research and suggested implications related to their future exploration.
基金supported by the National Natural Science Foundation of China(Grand No.12472066).
文摘A robust generalized continuum model called the wavelength-dependent strain gradient continuum model(WDSGM)has been proposed to predict dispersion properties of two-dimensional(2D)periodic lattice metamaterials.The key idea lies in replacing the classical Taylor expansion of displacement fields with a wavelength-dependent one,naturally leading to new equations of motion and therefore a significantly improved capability of predicting dispersion characteristics.For different 2D lattices,dispersion results derived from the proposed WDSGM are verified by comparing with those obtained from the discrete model and the existing strain gradient continuum model(SGM)in the irreducible Brillouin zone.Based on the proposed model,the effects of SG orders have been investigated.Results suggest that considering the wavelength-dependent Taylor expansion and increasing the SG order are beneficial to improving the predictive performance of continuum models.The proposed model is free of any instability issue which is challenging for many existing SG methods.Under given parameters,the proposed WDSGM with eighth-order truncation is enough to predict the dispersion relation of three lattices,i.e.,the square,triangular and hexagonal lattices throughout the irreducible Brillouin zone.
基金support by the Ministry of Education and Training of Vietnam for this research,under grant no.B2023-MBS-02.
文摘As prestressed concrete(PC)structures age,long-termeffects,e.g.,creep,shrinkage,and prestress losses,compromise their structural performance.Strengthening these aged PC beams has become a crucial matter.One effective solution is to use externally bonded fiber-reinforced polymer(FRP)sheets;however,limited research has been done on aged PC beams using the FRP,especially for beams with unbonded prestressing strands(UPC beams).Therefore,this research investigates the flexural strengthening efficacy of external FRP sheets on aged UPC beams with unbonded tendons.Aging minimally affected the failure modes of UPC beams,with nonstrengthened beams showing flexural failure via rebar yielding and concrete crushing,and FRP-strengthened beams failing due to FRP debonding and tensile reinforcement yielding,though tendons in the aged beams did not yield due to prestress losses,unlike the new beams.The U-wrap anchor curbed widespread debonding,leading to tensile reinforcement yielding and FRP rupture.Aging hastened crack growth and stiffness loss,increasing deflections and reducing load resistance,but FRP reinforcement mitigated these effects,enhancing cracking resistance by 14%over the unstrengthened aged beams and 7%over the new beams while boosting ultimate resistance by 9%above the non-strengthened new beams.Compared to the new FRP-strengthened beams,the aged counterparts had lower cracking resistance,stiffness and capacity—showing 20%higher deflections,7–9%lower serviceability loads,7%–17%reduced ultimate strength and 17%less deformability—due to prestress losses and premature FRP debonding.
基金supported by the National Natural Science Foundation of China(Grant no.52260009,U2102211)Yunnan Fundamental Research Projects(Grant no.202201BE070001-044,202401BE070001-025)+1 种基金Yunnan Fundamental Research Projects(Grant no.202301AT070405)the Yunnan Major Scientific and Technological Projects(No.202402AO370002).
文摘Active holes outperform photoelectron-mediated oxygen reduction in degrading recalcitrant organics under anaerobic conditions,yet their utilization is limited by rapid charge recombination.This challenge was addressed through Cu-based yolk-double-shell microspheres(Cu/Cu_(2)O@C-2shell)engineered via heterogeneous contraction and reduction strategies.Work function analyses confirm Schottky junction-driven electron transfer from Cu_(2)O to Cu,generating an internal electric field that suppresses backflow.Density functional theory reveals Cu-mediated enhancement of near-Fermi states(Cu 3d orbitals)and a directional Cu_(2)O→Cu→C electron pathway,spatially isolating holes in Cu_(2)O.Finite-difference time-domain simulations reveal light-induced electric field gradients in the dual-shell architecture:Cu^(0)-mediated localized surface plasmon resonance effect enhances surface field concentration,while hierarchical interfaces create an outward-to-inward gradient,directing electron migration inward and stabilizing oxidative holes at the surface.The optimized(Cu/Cu_(2)O)@C-2shell exhibits 38-fold higher tetracycline degradation under sunlight versus benchmarks,with treated water supporting Escherichia coli survival and wheat growth.This study provides a design strategy for the accumulation of long-lived holes on semiconductor photocatalysts.
基金supported by the Czech Science Foundation,under project No.20-12166S.
文摘The effect of using 2%and 10%sodium hydroxide solution as surface treatment of rape straw on its water vapor adsorption properties is analyzed in the relative humidity(RH)range of 0%to 98%.Scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and Fourier-transform infrared spectroscopy(FTIR)are used to investigate the morphological,chemical and structural changes of the treated straw surface.The mineral particles formed on the surface after the treatment are analyzed using X-ray diffraction(XRD).The application of sodium hydroxide solution results in the disruption of the straw surface.As the concentration of sodium hydroxide increases,the disruption of the straw surface increases,and the ability of the straw to adsorb water vapor also increases over the entire RH range.In addition to the surface disruption and chemical changes caused by the alkaline treatment,the differences in the equilibrium moisture content of treated and untreated rape straw can also be attributed to the formation of minerals on the straw surface,namely calcite for the 2%sodium hydroxide solution,and gaylussite and thermonatrite for the 10%solution.
