Floodplain wetlands are invaluable ecosystems providing numerous ecological benefits,yet they face a global crisis necessitating sustainable preservation efforts.This study examines the depletion of floodplain wetland...Floodplain wetlands are invaluable ecosystems providing numerous ecological benefits,yet they face a global crisis necessitating sustainable preservation efforts.This study examines the depletion of floodplain wetlands within the Hastinapur Wildlife Sanctuary(HWLS)in Uttar Pradesh.Encroachment activities such as grazing,agriculture,and human settlements have fragmented and degraded critical wetland ecosystems.Additionally,irrigation projects,dam construction,and water diversion have disrupted natural water flow and availability.To assess wetland inundation in 2023,five classification techniques were employed:Random Forest(RF),Support Vector Machine(SVM),artificial neural network(ANN),Spectral Information Divergence(SID),and Maximum Likelihood Classifier(MLC).SVM emerged as the most precise method,as determined by kappa coefficient and index-based validation.Consequently,the SVM classifier was used to model wetland inundation areas from 1983 to 2023 and analyze spatiotemporal changes and fragmentation patterns.The findings revealed that the SVM clas-sifier accurately mapped 2023 wetland areas.The modeled time-series data demonstrated a 62.55%and 38.12%reduction in inundated wetland areas over the past 40 years in the pre-and post-monsoon periods,respectively.Fragmentation analysis indicated an 86.27%decrease in large core wetland areas in the pre-monsoon period,signifying severe habitat degradation.This rapid decline in wetlands within protected areas raises concerns about their ecological impacts.By linking wetland loss to global sustainability objectives,this study underscores the global urgency for strengthened wetland protection measures and highlights the need for integrating wetland conservation into broader sustainable development goals.Effective policies and adaptive management strategies are crucial for preserving these ecosystems and their vital services,which are essential for biodiversity,climate regulation,and human well-being.展开更多
Abiotic oxygen formation predates photosynthesis,sustaining early chemical evolution,yet its elementary mechanisms remain contested.Here,we show the production pathways for molecular oxygen from doubly ionized carbon ...Abiotic oxygen formation predates photosynthesis,sustaining early chemical evolution,yet its elementary mechanisms remain contested.Here,we show the production pathways for molecular oxygen from doubly ionized carbon dioxide upon electron-impact.Through fragment ions and electron coincidence momentum imaging,we unambiguously determine the ionization mechanism by measuring the projectile energy loss in association with the C^(+) +O_(2)^(+) channel.Further potential energy and trajectory calculations enable us to elucidate the dynamical details of this fragmentation process,in which a bond rearrangement pathway is found to proceed via the structural deformation to a triangular intermediate.Moreover,we demonstrate a further roaming pathway for the formation of O_(2)^(+) from CO_(2)^(+) 2,in which a frustrated C-O bond cleavage leaves the O atom without sufficient energy to escape.The O atom then wanders around varied configuration spaces of the flat potential energy regions and forms a C-O-O_(2)^(+) intermediate prior to the final products C^(+) +O_(2)^(+).Considering the large quantities of free electrons in interstellar space,the processes revealed here are expected to be significant and should be incorporated into atmospheric evolution models.展开更多
To establish practical,evidence-based strategies for noninvasive assessment and referral of patients with metabolic dysfunction-associated steatotic liver disease(MASLD)in Japan,we must address the urgent clinical nee...To establish practical,evidence-based strategies for noninvasive assessment and referral of patients with metabolic dysfunction-associated steatotic liver disease(MASLD)in Japan,we must address the urgent clinical need for accurate risk stratification and timely specialist intervention.A panel of 11 Japanese hepatology experts conducted a modified Delphi process to evaluate consensus recommendations regarding the use of noninvasive tests(NITs),including the fibrosis-4 index,enhanced liver fibrosis test,Mac-2-binding protein glycosylation isomer,type IV collagen 7S,cytokeratin-18 fragments,and imaging modalities such as ultrasound elastography and magnetic resonance elastography,for MASLD assessment and clinical referral.Practical algorithms were developed based on current Japanese data and panel consensus.The expert panel validated the utility of NITs as reliable tools for identifying patients with MASLD at risk for advanced fibrosis.Sequential use of NITs improved diagnostic accuracy and referral appropriateness while minimizing unnecessary specialist consultations.The proposed algorithms offer stepwise guidance for primary care physicians,supporting efficient,evidence-based decisionmaking.However,prospective longitudinal studies remain necessary for full prognostic validation of NITs in MASLD management.Noninvasive testing algorithms enable effective risk stratification and referral for MASLD in real-world Japanese practice with anticipated benefit for patient outcomes and healthcare systems.Broader adoption and further validation are warranted.展开更多
This study presents a machine learning-based method for predicting fragment velocity distribution in warhead fragmentation under explosive loading condition.The fragment resultant velocities are correlated with key de...This study presents a machine learning-based method for predicting fragment velocity distribution in warhead fragmentation under explosive loading condition.The fragment resultant velocities are correlated with key design parameters including casing dimensions and detonation positions.The paper details the finite element analysis for fragmentation,the characterizations of the dynamic hardening and fracture models,the generation of comprehensive datasets,and the training of the ANN model.The results show the influence of casing dimensions on fragment velocity distributions,with the tendencies indicating increased resultant velocity with reduced thickness,increased length and diameter.The model's predictive capability is demonstrated through the accurate predictions for both training and testing datasets,showing its potential for the real-time prediction of fragmentation performance.展开更多
Rock fragmentation is an important indicator for assessing the quality of blasting operations.However,accurate prediction of rock fragmentation after blasting is challenging due to the complicated blasting parameters ...Rock fragmentation is an important indicator for assessing the quality of blasting operations.However,accurate prediction of rock fragmentation after blasting is challenging due to the complicated blasting parameters and rock properties.For this reason,optimized by the Bayesian optimization algorithm(BOA),four hybrid machine learning models,including random forest,adaptive boosting,gradient boosting,and extremely randomized trees,were developed in this study.A total of 102 data sets with seven input parameters(spacing-to-burden ratio,hole depth-to-burden ratio,burden-to-hole diameter ratio,stemming length-to-burden ratio,powder factor,in situ block size,and elastic modulus)and one output parameter(rock fragment mean size,X_(50))were adopted to train and validate the predictive models.The root mean square error(RMSE),the mean absolute error(MAE),and the coefficient of determination(R^(2))were used as the evaluation metrics.The evaluation results demonstrated that the hybrid models showed superior performance than the standalone models.The hybrid model consisting of gradient boosting and BOA(GBoost-BOA)achieved the best prediction results compared with the other hybrid models,with the highest R^(2)value of 0.96 and the smallest values of RMSE and MAE of 0.03 and 0.02,respectively.Furthermore,sensitivity analysis was carried out to study the effects of input variables on rock fragmentation.In situ block size(XB),elastic modulus(E),and stemming length-to-burden ratio(T/B)were set as the main influencing factors.The proposed hybrid model provided a reliable prediction result and thus could be considered an alternative approach for rock fragment prediction in mining engineering.展开更多
In the application of high-pressure water jet assisted breaking of deep underground rock engineering,the influence mechanism of rock temperature on the rock fragmentation process under jet action is still unclear.Ther...In the application of high-pressure water jet assisted breaking of deep underground rock engineering,the influence mechanism of rock temperature on the rock fragmentation process under jet action is still unclear.Therefore,the fluid evolution characteristics and rock fracture behavior during jet impingement were studied.The results indicate that the breaking process of high-temperature rock by jet impact can be divided into four stages:initial fluid-solid contact stage,intense thermal exchange stage,perforation and fracturing stage,and crack propagation and penetration stage.With the increase of rock temperature,the jet reflection angles and the time required for complete cooling of the impact surface significantly decrease,while the number of cracks and crack propagation rate significantly increase,and the rock breaking critical time is shortened by up to 34.5%.Based on numerical simulation results,it was found that the center temperature of granite at 400℃ rapidly decreased from 390 to 260℃ within 0.7 s under jet impact.In addition,a critical temperature and critical heat flux prediction model considering the staged breaking of hot rocks was established.These findings provide valuable insights to guide the water jet technology assisted deep ground hot rock excavation project.展开更多
Diabetes mellitus(DM)is a debilitating disorder that impacts all systems of the body and has been increasing in prevalence throughout the globe.DM represents a significant clinical challenge to care for individuals an...Diabetes mellitus(DM)is a debilitating disorder that impacts all systems of the body and has been increasing in prevalence throughout the globe.DM represents a significant clinical challenge to care for individuals and prevent the onset of chronic disability and ultimately death.Underlying cellular mechanisms for the onset and development of DM are multi-factorial in origin and involve pathways associated with the production of reactive oxygen species and the generation of oxidative stress as well as the dysfunction of mitochondrial cellular organelles,programmed cell death,and circadian rhythm impairments.These pathways can ultimately involve failure in the glymphatic pathway of the brain that is linked to circadian rhythms disorders during the loss of metabolic homeostasis.New studies incorporate a number of promising techniques to examine patients with metabolic disorders that can include machine learning and artificial intelligence pathways to potentially predict the onset of metabolic dysfunction.展开更多
This review examines the processes of laser heating,melting,evaporation,fragmentation,and breakdown of metal nanoparticles,as well as the dependences and values of the threshold laser parameters that initiate these pr...This review examines the processes of laser heating,melting,evaporation,fragmentation,and breakdown of metal nanoparticles,as well as the dependences and values of the threshold laser parameters that initiate these processes.Literature results are analyzed from experimental studies of these processes with gold,silver,and other nanoparticles,including laser surface melting and evaporation of nanoparticles and Coulomb fragmentation of nanoparticles by ultrashort laser pulses.A theoretical model and description of the thermal mechanisms of mentioned processes with metal(solid)nanoparticles in a liquid(solid)medium,initiated by the action of laser pulses with the threshold fluences,are presented.Comparison of the obtained results with experimental data confirms the accuracy of the model and makes it possible to use them to evaluate the parameters of laser thermal processing of nanoparticles.Applications of the processes include the laser melting,reshaping,and fragmentation of nanoparticles,the formation of nanostructures and nanonetworks,the laser processing of nanoparticles located on substrates,and their cladding on surfaces in various laser nanotechnologies.The use of laser ignition,combustion,and incandescence of nanoparticles is discussed,as is the use of nanoparticle-triggered laser breakdown for spectroscopy.These laser processes are used in photothermal nanotechnologies,nanoenergy,laser processing of nanoparticles,nonlinear optical devices,high-temperature material science,etc.In general,this review presents a modern picture of the state of laser technology and high-temperature processes with nanoparticles and their applications,being focused on the latest publications with an emphasis on recent results from 2021-2024.展开更多
Recent studies have shown that shorter periods of ejaculatory abstinence may enhance certain sperm parameters,but the molecular mechanisms underlying these improvements are still unclear.This study explored whether re...Recent studies have shown that shorter periods of ejaculatory abstinence may enhance certain sperm parameters,but the molecular mechanisms underlying these improvements are still unclear.This study explored whether reduced abstinence periods could improve semen quality,particularly for use in assisted reproductive technologies(ART).We analyzed semen samples from men with normal sperm counts(n=101)and those with low sperm motility or concentration(n=53)after 3-7 days of abstinence and then after 1-3h of abstinence,obtained from the Reproductive&Genetic Hospital of CITIC-Xiangya(Changsha,China).Physiological and biochemical sperm parameters were evaluated,and the dynamics of transfer RNA(tRNA)-derived fragments(tRFs)were analyzed using deep RNA sequencing in five consecutive samples from men with normal sperm counts.Our results revealed significant improvement in sperm motility and a decrease in the DNA fragmentation index after the 1-to 3-h abstinence period.Additionally,we identified 245 differentially expressed tRFs,and the mitogen-activated protein kinase(MAPK)signaling pathway was the most enriched.Further investigations showed significant changes in tRF-Lys-TTT and its target gene mitogen-activated protein kinase kinase 2(MAP2K2),which indicates a role of tRFs in improving sperm function.These findings provide new insights into how shorter abstinence periods influence sperm quality and suggest that tRFs may serve as biomarkers for male fertility.This research highlights the potential for optimizingART protocols and improving reproductive outcomes through molecular approaches that target sperm function.展开更多
Total or severe teratospermia affects the prognosis of fertility and causes serious problems for patients undergoing assisted reproduction[1].The pathophysiological mechanism of teratospermia is unclear.It has been sh...Total or severe teratospermia affects the prognosis of fertility and causes serious problems for patients undergoing assisted reproduction[1].The pathophysiological mechanism of teratospermia is unclear.It has been shown that patients with sperm parameters abnormalities and abnormal morphology have a high rate of fragmentation and sperm DNA decondensation[2,3],and that sperm DNA fragmentation analysis could be used as a predictor factor of fertility potential[4].展开更多
This paper is an attempt to explore the root of the modern paradox across multiple registers in order to uncover a persuasive pattern of contradiction that runs through the very fabric of contemporary existence.We dis...This paper is an attempt to explore the root of the modern paradox across multiple registers in order to uncover a persuasive pattern of contradiction that runs through the very fabric of contemporary existence.We discover that the very logic meant to emancipate the human subject-scientific mastery,bureaucratic order,economic growth,and many others,often recoil upon the subject,generating conditions of fragmentation,depersonalization,and spiritual aridity.Far from rejecting modernity wholesale,our task is a diagnostic one-to enter into the deep fabric of modernity and to decode its operating metaphors and interrogate what holds up the“scaffolding of collective life”.This is in a bid to find the rootedness of genuine human flourishing.Part of the answer,from our analysis,lies in a critical re-thinking within modernity without being subsumed by it.展开更多
“As a global citizen,I speak to you with fear.I fear increasing unpredictability and fragmentation that can easily result in conflict.And in conflict,no one wins-we all lose,”Matias Acosta,CEO of Italian cleantech f...“As a global citizen,I speak to you with fear.I fear increasing unpredictability and fragmentation that can easily result in conflict.And in conflict,no one wins-we all lose,”Matias Acosta,CEO of Italian cleantech firm Cosysense,told the audience at the China Today•Macao Salon dialogue in Hengqin,south China’s Guangdong Province,on July 27,2025.展开更多
Intact rocks with layered microstructures,such as gneiss,exhibit strong anisotropy.Although anisotropy in the macroscopic strength of gneiss has been widely reported,the role of microstructures in tensile mechanics re...Intact rocks with layered microstructures,such as gneiss,exhibit strong anisotropy.Although anisotropy in the macroscopic strength of gneiss has been widely reported,the role of microstructures in tensile mechanics remains largely unclear.Utilizing a range of methodologies,it was determined that the tensile strength,deformation,and fracturing behavior of Himalayan gneiss are predominantly influenced by biotite.In contrast to the behavior of other transversely isotropic rocks,the apparent tensile strength of the gneiss first decreased and then increased with anisotropic angleβ,rather than the widely reported monotonic increase or single-shoulder response.The shear sliding of biotite along cleavage planes caused stress concentrations in the surrounding brittle minerals,inducing cracks and reducing the overall tensile strength of the gneiss.Micro-observations of the relationship between cracks and biotite orientation identified three types of biotite crystal fragmentation:tensile fragmentation along cleavage planes,shear fragmentation along cleavage planes,and tensile fragmentation perpendicular to cleavage planes.Tensile and shear fragmentation of biotite along cleavage planes negatively affected the gneiss'macroscopic tensile strength.Conversely,when the tensile stress was parallel to the biotite cleavage planes,tensile fragmentation perpendicular to the cleavage planes increased the macroscopic tensile strength of the gneiss due to plastic deformation and high surface energy.Quantitative analysis of shear stress along biotite cleavage planes revealed the mechanical mechanism behind the reduced tensile strength of the East Himalayan gneisses near an anisotropic angle of 30°.These results elucidated the influence of grain-level anisotropy on the macroscopic tensile mechanical properties of intact layered rocks.展开更多
Roads are a leading cause of habitat fragmentation and may reduce bird populations by increasing nest predation rates.However,few studies have investigated the effects of traffic volume on the reproductive success of ...Roads are a leading cause of habitat fragmentation and may reduce bird populations by increasing nest predation rates.However,few studies have investigated the effects of traffic volume on the reproductive success of roadside birds in the neotropics.Our goal was to evaluate the effects of spatial,temporal,and vehicle flow variations on the survival of artificial open-cup nests.The study was carried out in a nature reserve on the side of a highway during the breeding season(from October to March)in two restinga(sand-coastal plain)phytophysiognomies in southeastern Brazil:non-floodable(open)and floodable(closed).One hundred thirty nests were distributed along transects ranging from 3 m to 300 m from the highway in each vegetation type(totaling 260 nests).The nests were checked every three days for their status(depredated or intact)over 12 days,and new nests were subsequently placed near sampling points of depredated or successful nests.We estimated survival using logistic exposure generalized linear and additive mixed models.At the end of the 180 days of the experiment,33%of 6202 nests were successful.Nest survival was higher in open restinga than in closed restinga.In both habitats,nest survival was lowest mid-season and highest at the beginning and end.Survival rates peaked near the highway,declined up to 50 m away,then showed a slight increase.Finally,survival increased at moderate-to-high traffic volumes(∼22,000 vehicles/day),particularly in open restinga.We suggest that spatial,temporal,and habitat-specific highway impacts(e.g.,noise,vibration,visual stimuli)can lead to variations in the activity of nest predators,generating fluctuations in nest survival associated with predator behavior.展开更多
This study investigates the effect of shock velocity(u_(p))on damage evolution mechanisms in nanocrystalline iron via molecular dynamics simulations.As u_(p)increases,shock wave propagation accelerates,and stress dist...This study investigates the effect of shock velocity(u_(p))on damage evolution mechanisms in nanocrystalline iron via molecular dynamics simulations.As u_(p)increases,shock wave propagation accelerates,and stress distribution transitions from grain boundary concentration to homogeneity.This causes a transition in fracture mode from cleavage to ductile behavior.When u_(p)exceeds 1.5 km·s^(-1),micro-spallation emerges as the dominant failure mode.During micro-spallation,localized melting within the material impedes the propagation of the shock wave.As u_(p)increases,the growth rate of the void volume fraction initially rises but then decreases.Higher u_(p)leads to earlier void nucleation.At lower u_(p),the cavitation of the model is mainly characterized by the growth and penetration of a few voids.With increasing u_(p),the number of voids grows,and their interactions expand the delamination damage region.The spall strength demonstrates stage-specific dependence on u_(p).In the classical spallation stage(C_Ⅰ),temperature softening reduces spall strength.In the plastic strengthening regime(C_Ⅱ),strain hardening enhances spall strength.In the micro-spallation stage(M_Ⅲ),further increases in u_(p)cause melting during tensile and compressive phases,reducing spall strength.Finally,in the compressionmelting regime(M_Ⅳ),local temperatures exceed the melting point,diminishing plastic damage and accelerating spall strength reduction.This study provides new insights into the dynamic response of nanocrystalline iron.展开更多
This communication looks at the photo-oxidation of polythene and polypropylene plastic bottle tops that are placed on soil in a hot arid environment. The degree of oxidation of the plastic is monitored by FT-IR spectr...This communication looks at the photo-oxidation of polythene and polypropylene plastic bottle tops that are placed on soil in a hot arid environment. The degree of oxidation of the plastic is monitored by FT-IR spectroscopy. It is noted that while different bottle top types photo-oxidize at different rates, all show an appreciable level of oxidation after half a year of exposure to the environment. The oxidation leads to brittleness of the plastic, which leads to fissure formation in bottle tops of little thickness. This leads to fragmentation of the material upon impact, making plastic bottle tops an appreciable source of microplastics.展开更多
Fragmentation is a common phenomenon in the runout process of large rockslides.Rocks have different strengths under the influence of the rock type and weathering degree,resulting in varying fragmentation characteristi...Fragmentation is a common phenomenon in the runout process of large rockslides.Rocks have different strengths under the influence of the rock type and weathering degree,resulting in varying fragmentation characteristics.However,the limited understanding of how rock strength influences the postfragmentation kinematic characteristics of rockslides is limited.Taking a natural rockslide as an example,this paper quantitatively analyzes the runout and deposition of the rockslide using the discrete element method(DEM)and examines the impacts of the rock strength on the runout and deposition characteristics of the rockslide.The results reveal that(1)Rock strength significantly influences fragmentation and runout characteristics:medium-to-high strength rocks exhibit two-stage fragmentation(10-20 s and 55-65 s),while weak-strength rocks achieve 98%fragmentation within 20 s.Optimal kinetic energy conversion occurs in medium-strength rocks,with a maximum velocity difference of 39.3 m/s between the anterior and posterior edges.(2)The sudden change in the cross-sectional dimensions of high-strength rocks under a high spreading velocity(>60 m/s)may amplify air blast hazards.(3)Deposition patterns reveal that the spatial distribution of fragments preserves original positional order;high-strength rocks produce larger fragments(nominal fragment size increases from 0.028 of weak-strength rocks to 0.607);and centroid displacement increases from 1907 m to 2117 m with rock strength in open terrains.(4)Energy dissipation analysis shows that frictional dissipation(>60%)>collisional dissipation(~37%)>>fragmentation dissipation(<2%)in the process of rockslide runout.The rock strength induces<5%variation in partitioning of energy dissipation.展开更多
Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves a...Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves and fragments.To explore the protective effect of polyurea elastomer on LFC,the damage characteristics of polyurea coated liquid-filled container(PLFC)under the combined loading of blast shock wave and fragments were studied experimentally.The microstructure of the polyurea layer was observed by scanning electron microscopy,and the fracture and self-healing phenomena were analyzed.The simulation approach was used to explain the combined blast-and fragments-induced on the PLFC in detail.Finally,the effects of shock wave and fragment alone and in combination on the damage of PLFC were comprehensively compared.Results showed that the polyurea reduces the perforation rate of the fragment to the LFC,and the self-healing phenomenon could also reduce the liquid loss rate inside the container.The polyurea reduces the degree of depression in the center of the LFC,resulting in a decrease in the distance between adjacent fragments penetrating the LFC,and an increase in the probability of transfixion and fracture between holes.Under the close-in blast,the detonation shock wave reached the LFC before the fragment.Polyurea does not all have an enhanced effect on the protection of LFC.The presence of internal water enhances the anti-blast performance of the container,and the hydrodynamic ram(HRAM)formed by the fragment impacting the water aggravated the plastic deformation of the container.The combined action has an enhancement effect on the deformation of the LFC.The depth of the container depression was 27%higher than that of the blast shock wave alone;thus,it cannot be simply summarized as linear superposition.展开更多
Habitat fragmentation poses a significant threat to bird communities, especially those in open and semi-open ecosystems such as steppes. This study investigates how steppe birds adapt to and utilize fragmented habitat...Habitat fragmentation poses a significant threat to bird communities, especially those in open and semi-open ecosystems such as steppes. This study investigates how steppe birds adapt to and utilize fragmented habitats by combining niche modeling with ecological trait analysis. We conducted standardized point surveys to examine the habitat preferences of 32 bird species in Inner Mongolia, China, and quantified their habitat niche parameters using the Outlying Mean Index (OMI). Our results reveal distinct habitat preferences among species, with some thriving in intact environments while others are better adapted to fragmented areas. Grassland species showed high specialization along the fragmentation gradient, while others exhibited adaptability to varying levels of fragmentation. Using a Generalized Additive Model (GAM), we identified three key traits influencing habitat occupancy: hand-wing index, body mass, and range size. Specifically, species with medium hand-wing indices, moderate body mass, and larger range sizes were more likely to occupy heavily fragmented habitats. These findings provide empirical evidence on how habitat fragmentation affects bird species in steppe ecosystems. The study highlights the importance of functional traits in understanding avian responses to habitat fragmentation and offers a foundation for developing effective conservation strategies to preserve biodiversity in fragmented landscapes.展开更多
Rockfall represents a significant geological hazard in mountainous regions,characterized by a sudden and unpredictable feature.The process of dynamic fragmentation and energy conversion in a rockfall event remains com...Rockfall represents a significant geological hazard in mountainous regions,characterized by a sudden and unpredictable feature.The process of dynamic fragmentation and energy conversion in a rockfall event remains complex and not fully understood.This study aims to gain a further understanding of the energy transfer mechanism during rockfall impact and fragmentation by impact tests using a variety of rock-like sphere specimens.The experiments mainly focus on the quantitative correlation between fragmentation degree and influence factors,i.e.impact angle and velocity on steel and granite slabs.The analysis focuses on the energy distribution characteristics,energy dissipation mechanisms,and the energy conversion rate of the fragments during impact and fragmentation.The results show that there is a significant correlation between the energy conversion rate and the fragmentation degree.In normal impact tests,elasto-plastic deformation energy and fracture energy are found to be two primary categories of energy dissipation.The proportion of total kinetic energy after impact is inversely proportional to the initial energy.A comparative analysis between normal and inclined slab impact tests reveals that the impact angle significantly influences the energy conversion rate,which controls the fragmentation degree as well.In addition,the fragmentation degree is inversely proportional to the restitution coefficient.These findings contribute to a better understanding of the energy conversion mechanism during rockfall impact and fragmentation,providing valuable insight for the development of effective strategies to mitigate such rockfall hazards.展开更多
基金support through the“Trans-Disciplinary Research”Grant(No.R/Dev/IoE/TDRProjects/2023-24/61658),which played a crucial role in enabling this research endeavor.
文摘Floodplain wetlands are invaluable ecosystems providing numerous ecological benefits,yet they face a global crisis necessitating sustainable preservation efforts.This study examines the depletion of floodplain wetlands within the Hastinapur Wildlife Sanctuary(HWLS)in Uttar Pradesh.Encroachment activities such as grazing,agriculture,and human settlements have fragmented and degraded critical wetland ecosystems.Additionally,irrigation projects,dam construction,and water diversion have disrupted natural water flow and availability.To assess wetland inundation in 2023,five classification techniques were employed:Random Forest(RF),Support Vector Machine(SVM),artificial neural network(ANN),Spectral Information Divergence(SID),and Maximum Likelihood Classifier(MLC).SVM emerged as the most precise method,as determined by kappa coefficient and index-based validation.Consequently,the SVM classifier was used to model wetland inundation areas from 1983 to 2023 and analyze spatiotemporal changes and fragmentation patterns.The findings revealed that the SVM clas-sifier accurately mapped 2023 wetland areas.The modeled time-series data demonstrated a 62.55%and 38.12%reduction in inundated wetland areas over the past 40 years in the pre-and post-monsoon periods,respectively.Fragmentation analysis indicated an 86.27%decrease in large core wetland areas in the pre-monsoon period,signifying severe habitat degradation.This rapid decline in wetlands within protected areas raises concerns about their ecological impacts.By linking wetland loss to global sustainability objectives,this study underscores the global urgency for strengthened wetland protection measures and highlights the need for integrating wetland conservation into broader sustainable development goals.Effective policies and adaptive management strategies are crucial for preserving these ecosystems and their vital services,which are essential for biodiversity,climate regulation,and human well-being.
基金supported by the National Natural Science Foundation of China (Grant Nos.12325406,92261201,12404305,and W2512072)the Shaanxi Province Natural Science Fundamental Research Project (Grant Nos.2023JC-XJ-03 and23JSQ013)the China Postdoctoral Science Foundation (Grant Nos.BX20240286 and 2024M7625)。
文摘Abiotic oxygen formation predates photosynthesis,sustaining early chemical evolution,yet its elementary mechanisms remain contested.Here,we show the production pathways for molecular oxygen from doubly ionized carbon dioxide upon electron-impact.Through fragment ions and electron coincidence momentum imaging,we unambiguously determine the ionization mechanism by measuring the projectile energy loss in association with the C^(+) +O_(2)^(+) channel.Further potential energy and trajectory calculations enable us to elucidate the dynamical details of this fragmentation process,in which a bond rearrangement pathway is found to proceed via the structural deformation to a triangular intermediate.Moreover,we demonstrate a further roaming pathway for the formation of O_(2)^(+) from CO_(2)^(+) 2,in which a frustrated C-O bond cleavage leaves the O atom without sufficient energy to escape.The O atom then wanders around varied configuration spaces of the flat potential energy regions and forms a C-O-O_(2)^(+) intermediate prior to the final products C^(+) +O_(2)^(+).Considering the large quantities of free electrons in interstellar space,the processes revealed here are expected to be significant and should be incorporated into atmospheric evolution models.
基金Supported by Japan Society for the Promotion of Science KAKENHI,No.25K11274.
文摘To establish practical,evidence-based strategies for noninvasive assessment and referral of patients with metabolic dysfunction-associated steatotic liver disease(MASLD)in Japan,we must address the urgent clinical need for accurate risk stratification and timely specialist intervention.A panel of 11 Japanese hepatology experts conducted a modified Delphi process to evaluate consensus recommendations regarding the use of noninvasive tests(NITs),including the fibrosis-4 index,enhanced liver fibrosis test,Mac-2-binding protein glycosylation isomer,type IV collagen 7S,cytokeratin-18 fragments,and imaging modalities such as ultrasound elastography and magnetic resonance elastography,for MASLD assessment and clinical referral.Practical algorithms were developed based on current Japanese data and panel consensus.The expert panel validated the utility of NITs as reliable tools for identifying patients with MASLD at risk for advanced fibrosis.Sequential use of NITs improved diagnostic accuracy and referral appropriateness while minimizing unnecessary specialist consultations.The proposed algorithms offer stepwise guidance for primary care physicians,supporting efficient,evidence-based decisionmaking.However,prospective longitudinal studies remain necessary for full prognostic validation of NITs in MASLD management.Noninvasive testing algorithms enable effective risk stratification and referral for MASLD in real-world Japanese practice with anticipated benefit for patient outcomes and healthcare systems.Broader adoption and further validation are warranted.
基金supported by Poongsan-KAIST Future Research Center Projectthe fund support provided by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(Grant No.2023R1A2C2005661)。
文摘This study presents a machine learning-based method for predicting fragment velocity distribution in warhead fragmentation under explosive loading condition.The fragment resultant velocities are correlated with key design parameters including casing dimensions and detonation positions.The paper details the finite element analysis for fragmentation,the characterizations of the dynamic hardening and fracture models,the generation of comprehensive datasets,and the training of the ANN model.The results show the influence of casing dimensions on fragment velocity distributions,with the tendencies indicating increased resultant velocity with reduced thickness,increased length and diameter.The model's predictive capability is demonstrated through the accurate predictions for both training and testing datasets,showing its potential for the real-time prediction of fragmentation performance.
基金National Natural Science Foundation of China,Grant/Award Number:52374153。
文摘Rock fragmentation is an important indicator for assessing the quality of blasting operations.However,accurate prediction of rock fragmentation after blasting is challenging due to the complicated blasting parameters and rock properties.For this reason,optimized by the Bayesian optimization algorithm(BOA),four hybrid machine learning models,including random forest,adaptive boosting,gradient boosting,and extremely randomized trees,were developed in this study.A total of 102 data sets with seven input parameters(spacing-to-burden ratio,hole depth-to-burden ratio,burden-to-hole diameter ratio,stemming length-to-burden ratio,powder factor,in situ block size,and elastic modulus)and one output parameter(rock fragment mean size,X_(50))were adopted to train and validate the predictive models.The root mean square error(RMSE),the mean absolute error(MAE),and the coefficient of determination(R^(2))were used as the evaluation metrics.The evaluation results demonstrated that the hybrid models showed superior performance than the standalone models.The hybrid model consisting of gradient boosting and BOA(GBoost-BOA)achieved the best prediction results compared with the other hybrid models,with the highest R^(2)value of 0.96 and the smallest values of RMSE and MAE of 0.03 and 0.02,respectively.Furthermore,sensitivity analysis was carried out to study the effects of input variables on rock fragmentation.In situ block size(XB),elastic modulus(E),and stemming length-to-burden ratio(T/B)were set as the main influencing factors.The proposed hybrid model provided a reliable prediction result and thus could be considered an alternative approach for rock fragment prediction in mining engineering.
基金supported by National Natural Science Foundation of China (No.U23A20597)National Major Science and Technology Project of China (No.2024ZD1003803)+1 种基金Chongqing Science Fund for Distinguished Young Scholars of Chongqing Municipality (No.CSTB2022NSCQ-JQX0028)Natural Science Foundation of Chongqing (No.CSTB2024NSCQ-MSX0503)。
文摘In the application of high-pressure water jet assisted breaking of deep underground rock engineering,the influence mechanism of rock temperature on the rock fragmentation process under jet action is still unclear.Therefore,the fluid evolution characteristics and rock fracture behavior during jet impingement were studied.The results indicate that the breaking process of high-temperature rock by jet impact can be divided into four stages:initial fluid-solid contact stage,intense thermal exchange stage,perforation and fracturing stage,and crack propagation and penetration stage.With the increase of rock temperature,the jet reflection angles and the time required for complete cooling of the impact surface significantly decrease,while the number of cracks and crack propagation rate significantly increase,and the rock breaking critical time is shortened by up to 34.5%.Based on numerical simulation results,it was found that the center temperature of granite at 400℃ rapidly decreased from 390 to 260℃ within 0.7 s under jet impact.In addition,a critical temperature and critical heat flux prediction model considering the staged breaking of hot rocks was established.These findings provide valuable insights to guide the water jet technology assisted deep ground hot rock excavation project.
基金Supported by American Diabetes AssociationAmerican Heart Association+3 种基金NIH NIEHSNIH NIANIH NINDSand NIH ARRA.
文摘Diabetes mellitus(DM)is a debilitating disorder that impacts all systems of the body and has been increasing in prevalence throughout the globe.DM represents a significant clinical challenge to care for individuals and prevent the onset of chronic disability and ultimately death.Underlying cellular mechanisms for the onset and development of DM are multi-factorial in origin and involve pathways associated with the production of reactive oxygen species and the generation of oxidative stress as well as the dysfunction of mitochondrial cellular organelles,programmed cell death,and circadian rhythm impairments.These pathways can ultimately involve failure in the glymphatic pathway of the brain that is linked to circadian rhythms disorders during the loss of metabolic homeostasis.New studies incorporate a number of promising techniques to examine patients with metabolic disorders that can include machine learning and artificial intelligence pathways to potentially predict the onset of metabolic dysfunction.
文摘This review examines the processes of laser heating,melting,evaporation,fragmentation,and breakdown of metal nanoparticles,as well as the dependences and values of the threshold laser parameters that initiate these processes.Literature results are analyzed from experimental studies of these processes with gold,silver,and other nanoparticles,including laser surface melting and evaporation of nanoparticles and Coulomb fragmentation of nanoparticles by ultrashort laser pulses.A theoretical model and description of the thermal mechanisms of mentioned processes with metal(solid)nanoparticles in a liquid(solid)medium,initiated by the action of laser pulses with the threshold fluences,are presented.Comparison of the obtained results with experimental data confirms the accuracy of the model and makes it possible to use them to evaluate the parameters of laser thermal processing of nanoparticles.Applications of the processes include the laser melting,reshaping,and fragmentation of nanoparticles,the formation of nanostructures and nanonetworks,the laser processing of nanoparticles located on substrates,and their cladding on surfaces in various laser nanotechnologies.The use of laser ignition,combustion,and incandescence of nanoparticles is discussed,as is the use of nanoparticle-triggered laser breakdown for spectroscopy.These laser processes are used in photothermal nanotechnologies,nanoenergy,laser processing of nanoparticles,nonlinear optical devices,high-temperature material science,etc.In general,this review presents a modern picture of the state of laser technology and high-temperature processes with nanoparticles and their applications,being focused on the latest publications with an emphasis on recent results from 2021-2024.
基金supported by grants from the National Key R&D Program of China(2022YFC2702700)Natural Science Foundation of Hunan Province(2024JJ6725 and 2022JJ40657)+1 种基金Hunan Provincial Grant for Innovative Province Construction(2019SK4012)the Reproductive and Genetic Hospital of CITIC-Xiangya Foundation(YNXM-202003).
文摘Recent studies have shown that shorter periods of ejaculatory abstinence may enhance certain sperm parameters,but the molecular mechanisms underlying these improvements are still unclear.This study explored whether reduced abstinence periods could improve semen quality,particularly for use in assisted reproductive technologies(ART).We analyzed semen samples from men with normal sperm counts(n=101)and those with low sperm motility or concentration(n=53)after 3-7 days of abstinence and then after 1-3h of abstinence,obtained from the Reproductive&Genetic Hospital of CITIC-Xiangya(Changsha,China).Physiological and biochemical sperm parameters were evaluated,and the dynamics of transfer RNA(tRNA)-derived fragments(tRFs)were analyzed using deep RNA sequencing in five consecutive samples from men with normal sperm counts.Our results revealed significant improvement in sperm motility and a decrease in the DNA fragmentation index after the 1-to 3-h abstinence period.Additionally,we identified 245 differentially expressed tRFs,and the mitogen-activated protein kinase(MAPK)signaling pathway was the most enriched.Further investigations showed significant changes in tRF-Lys-TTT and its target gene mitogen-activated protein kinase kinase 2(MAP2K2),which indicates a role of tRFs in improving sperm function.These findings provide new insights into how shorter abstinence periods influence sperm quality and suggest that tRFs may serve as biomarkers for male fertility.This research highlights the potential for optimizingART protocols and improving reproductive outcomes through molecular approaches that target sperm function.
文摘Total or severe teratospermia affects the prognosis of fertility and causes serious problems for patients undergoing assisted reproduction[1].The pathophysiological mechanism of teratospermia is unclear.It has been shown that patients with sperm parameters abnormalities and abnormal morphology have a high rate of fragmentation and sperm DNA decondensation[2,3],and that sperm DNA fragmentation analysis could be used as a predictor factor of fertility potential[4].
文摘This paper is an attempt to explore the root of the modern paradox across multiple registers in order to uncover a persuasive pattern of contradiction that runs through the very fabric of contemporary existence.We discover that the very logic meant to emancipate the human subject-scientific mastery,bureaucratic order,economic growth,and many others,often recoil upon the subject,generating conditions of fragmentation,depersonalization,and spiritual aridity.Far from rejecting modernity wholesale,our task is a diagnostic one-to enter into the deep fabric of modernity and to decode its operating metaphors and interrogate what holds up the“scaffolding of collective life”.This is in a bid to find the rootedness of genuine human flourishing.Part of the answer,from our analysis,lies in a critical re-thinking within modernity without being subsumed by it.
文摘“As a global citizen,I speak to you with fear.I fear increasing unpredictability and fragmentation that can easily result in conflict.And in conflict,no one wins-we all lose,”Matias Acosta,CEO of Italian cleantech firm Cosysense,told the audience at the China Today•Macao Salon dialogue in Hengqin,south China’s Guangdong Province,on July 27,2025.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0904)the National Natural Science Foundation of China(Grant No.42402277)the Fundamental Research Funds for the Central Universities(Grant No.300102264902).
文摘Intact rocks with layered microstructures,such as gneiss,exhibit strong anisotropy.Although anisotropy in the macroscopic strength of gneiss has been widely reported,the role of microstructures in tensile mechanics remains largely unclear.Utilizing a range of methodologies,it was determined that the tensile strength,deformation,and fracturing behavior of Himalayan gneiss are predominantly influenced by biotite.In contrast to the behavior of other transversely isotropic rocks,the apparent tensile strength of the gneiss first decreased and then increased with anisotropic angleβ,rather than the widely reported monotonic increase or single-shoulder response.The shear sliding of biotite along cleavage planes caused stress concentrations in the surrounding brittle minerals,inducing cracks and reducing the overall tensile strength of the gneiss.Micro-observations of the relationship between cracks and biotite orientation identified three types of biotite crystal fragmentation:tensile fragmentation along cleavage planes,shear fragmentation along cleavage planes,and tensile fragmentation perpendicular to cleavage planes.Tensile and shear fragmentation of biotite along cleavage planes negatively affected the gneiss'macroscopic tensile strength.Conversely,when the tensile stress was parallel to the biotite cleavage planes,tensile fragmentation perpendicular to the cleavage planes increased the macroscopic tensile strength of the gneiss due to plastic deformation and high surface energy.Quantitative analysis of shear stress along biotite cleavage planes revealed the mechanical mechanism behind the reduced tensile strength of the East Himalayan gneisses near an anisotropic angle of 30°.These results elucidated the influence of grain-level anisotropy on the macroscopic tensile mechanical properties of intact layered rocks.
基金supports were provided by the Concessionária Rodovia do Sol/SA(RodoSol)the Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq,grant:45.6446/2014/1)+2 种基金the São Paulo Research Foundation(FAPESP,Process Number#2024/13237-3)PD received a postdoctoral fellowship from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior(CAPES,grant:88887.469218/2019-00)CD is grateful to CNPq(Bolsa de Produtividade em Pesquisa,grant:308997/2023-9).
文摘Roads are a leading cause of habitat fragmentation and may reduce bird populations by increasing nest predation rates.However,few studies have investigated the effects of traffic volume on the reproductive success of roadside birds in the neotropics.Our goal was to evaluate the effects of spatial,temporal,and vehicle flow variations on the survival of artificial open-cup nests.The study was carried out in a nature reserve on the side of a highway during the breeding season(from October to March)in two restinga(sand-coastal plain)phytophysiognomies in southeastern Brazil:non-floodable(open)and floodable(closed).One hundred thirty nests were distributed along transects ranging from 3 m to 300 m from the highway in each vegetation type(totaling 260 nests).The nests were checked every three days for their status(depredated or intact)over 12 days,and new nests were subsequently placed near sampling points of depredated or successful nests.We estimated survival using logistic exposure generalized linear and additive mixed models.At the end of the 180 days of the experiment,33%of 6202 nests were successful.Nest survival was higher in open restinga than in closed restinga.In both habitats,nest survival was lowest mid-season and highest at the beginning and end.Survival rates peaked near the highway,declined up to 50 m away,then showed a slight increase.Finally,survival increased at moderate-to-high traffic volumes(∼22,000 vehicles/day),particularly in open restinga.We suggest that spatial,temporal,and habitat-specific highway impacts(e.g.,noise,vibration,visual stimuli)can lead to variations in the activity of nest predators,generating fluctuations in nest survival associated with predator behavior.
文摘This study investigates the effect of shock velocity(u_(p))on damage evolution mechanisms in nanocrystalline iron via molecular dynamics simulations.As u_(p)increases,shock wave propagation accelerates,and stress distribution transitions from grain boundary concentration to homogeneity.This causes a transition in fracture mode from cleavage to ductile behavior.When u_(p)exceeds 1.5 km·s^(-1),micro-spallation emerges as the dominant failure mode.During micro-spallation,localized melting within the material impedes the propagation of the shock wave.As u_(p)increases,the growth rate of the void volume fraction initially rises but then decreases.Higher u_(p)leads to earlier void nucleation.At lower u_(p),the cavitation of the model is mainly characterized by the growth and penetration of a few voids.With increasing u_(p),the number of voids grows,and their interactions expand the delamination damage region.The spall strength demonstrates stage-specific dependence on u_(p).In the classical spallation stage(C_Ⅰ),temperature softening reduces spall strength.In the plastic strengthening regime(C_Ⅱ),strain hardening enhances spall strength.In the micro-spallation stage(M_Ⅲ),further increases in u_(p)cause melting during tensile and compressive phases,reducing spall strength.Finally,in the compressionmelting regime(M_Ⅳ),local temperatures exceed the melting point,diminishing plastic damage and accelerating spall strength reduction.This study provides new insights into the dynamic response of nanocrystalline iron.
文摘This communication looks at the photo-oxidation of polythene and polypropylene plastic bottle tops that are placed on soil in a hot arid environment. The degree of oxidation of the plastic is monitored by FT-IR spectroscopy. It is noted that while different bottle top types photo-oxidize at different rates, all show an appreciable level of oxidation after half a year of exposure to the environment. The oxidation leads to brittleness of the plastic, which leads to fissure formation in bottle tops of little thickness. This leads to fragmentation of the material upon impact, making plastic bottle tops an appreciable source of microplastics.
基金support from the National Natural Science Foundation of China(41977233,U22A20601)Student Research Training Program of Fuzhou University(S202210386061).
文摘Fragmentation is a common phenomenon in the runout process of large rockslides.Rocks have different strengths under the influence of the rock type and weathering degree,resulting in varying fragmentation characteristics.However,the limited understanding of how rock strength influences the postfragmentation kinematic characteristics of rockslides is limited.Taking a natural rockslide as an example,this paper quantitatively analyzes the runout and deposition of the rockslide using the discrete element method(DEM)and examines the impacts of the rock strength on the runout and deposition characteristics of the rockslide.The results reveal that(1)Rock strength significantly influences fragmentation and runout characteristics:medium-to-high strength rocks exhibit two-stage fragmentation(10-20 s and 55-65 s),while weak-strength rocks achieve 98%fragmentation within 20 s.Optimal kinetic energy conversion occurs in medium-strength rocks,with a maximum velocity difference of 39.3 m/s between the anterior and posterior edges.(2)The sudden change in the cross-sectional dimensions of high-strength rocks under a high spreading velocity(>60 m/s)may amplify air blast hazards.(3)Deposition patterns reveal that the spatial distribution of fragments preserves original positional order;high-strength rocks produce larger fragments(nominal fragment size increases from 0.028 of weak-strength rocks to 0.607);and centroid displacement increases from 1907 m to 2117 m with rock strength in open terrains.(4)Energy dissipation analysis shows that frictional dissipation(>60%)>collisional dissipation(~37%)>>fragmentation dissipation(<2%)in the process of rockslide runout.The rock strength induces<5%variation in partitioning of energy dissipation.
基金supported by the National Natural Science Foundation of China(Grant Nos.12102480,52278543 and 51978660)Natural Science Foundation of Jiangsu Province(Grant No.BK20231489)。
文摘Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves and fragments.To explore the protective effect of polyurea elastomer on LFC,the damage characteristics of polyurea coated liquid-filled container(PLFC)under the combined loading of blast shock wave and fragments were studied experimentally.The microstructure of the polyurea layer was observed by scanning electron microscopy,and the fracture and self-healing phenomena were analyzed.The simulation approach was used to explain the combined blast-and fragments-induced on the PLFC in detail.Finally,the effects of shock wave and fragment alone and in combination on the damage of PLFC were comprehensively compared.Results showed that the polyurea reduces the perforation rate of the fragment to the LFC,and the self-healing phenomenon could also reduce the liquid loss rate inside the container.The polyurea reduces the degree of depression in the center of the LFC,resulting in a decrease in the distance between adjacent fragments penetrating the LFC,and an increase in the probability of transfixion and fracture between holes.Under the close-in blast,the detonation shock wave reached the LFC before the fragment.Polyurea does not all have an enhanced effect on the protection of LFC.The presence of internal water enhances the anti-blast performance of the container,and the hydrodynamic ram(HRAM)formed by the fragment impacting the water aggravated the plastic deformation of the container.The combined action has an enhancement effect on the deformation of the LFC.The depth of the container depression was 27%higher than that of the blast shock wave alone;thus,it cannot be simply summarized as linear superposition.
基金supported by the National Natural Science Foundation of China(No.32201304)the Fundamental Research Funds for the Central Universities(No.2412022QD026).
文摘Habitat fragmentation poses a significant threat to bird communities, especially those in open and semi-open ecosystems such as steppes. This study investigates how steppe birds adapt to and utilize fragmented habitats by combining niche modeling with ecological trait analysis. We conducted standardized point surveys to examine the habitat preferences of 32 bird species in Inner Mongolia, China, and quantified their habitat niche parameters using the Outlying Mean Index (OMI). Our results reveal distinct habitat preferences among species, with some thriving in intact environments while others are better adapted to fragmented areas. Grassland species showed high specialization along the fragmentation gradient, while others exhibited adaptability to varying levels of fragmentation. Using a Generalized Additive Model (GAM), we identified three key traits influencing habitat occupancy: hand-wing index, body mass, and range size. Specifically, species with medium hand-wing indices, moderate body mass, and larger range sizes were more likely to occupy heavily fragmented habitats. These findings provide empirical evidence on how habitat fragmentation affects bird species in steppe ecosystems. The study highlights the importance of functional traits in understanding avian responses to habitat fragmentation and offers a foundation for developing effective conservation strategies to preserve biodiversity in fragmented landscapes.
基金financially supported by the Joint Funds of the National Natural Science Foundation of China(Grant No.U23A2047)the General Project of the Natural Science Foundation of Sichuan Province,China(Grant No.2023NSFSC0264).
文摘Rockfall represents a significant geological hazard in mountainous regions,characterized by a sudden and unpredictable feature.The process of dynamic fragmentation and energy conversion in a rockfall event remains complex and not fully understood.This study aims to gain a further understanding of the energy transfer mechanism during rockfall impact and fragmentation by impact tests using a variety of rock-like sphere specimens.The experiments mainly focus on the quantitative correlation between fragmentation degree and influence factors,i.e.impact angle and velocity on steel and granite slabs.The analysis focuses on the energy distribution characteristics,energy dissipation mechanisms,and the energy conversion rate of the fragments during impact and fragmentation.The results show that there is a significant correlation between the energy conversion rate and the fragmentation degree.In normal impact tests,elasto-plastic deformation energy and fracture energy are found to be two primary categories of energy dissipation.The proportion of total kinetic energy after impact is inversely proportional to the initial energy.A comparative analysis between normal and inclined slab impact tests reveals that the impact angle significantly influences the energy conversion rate,which controls the fragmentation degree as well.In addition,the fragmentation degree is inversely proportional to the restitution coefficient.These findings contribute to a better understanding of the energy conversion mechanism during rockfall impact and fragmentation,providing valuable insight for the development of effective strategies to mitigate such rockfall hazards.
