Laboratory Experiments Research Articles

Molecular Insights into CO2 Diffusion Behavior in Crude Oil

CO2 flooding plays a significant part in enhancing oil recovery and is essential to achieving CCUS (Carbon Capture, Utilization, and Storage). This study aims to understand the fundamental theory of CO2 dissolving and diffusing into crude oil and how these processes vary under reasonable reservoir conditions. In this paper, we primarily use molecular dynamics simulation to construct a multi-component crude oil model with 17 hydrocarbons, which is on the basis of a component analysis of oil samples through laboratory experiments. Then, the CO2 dissolving capacity of the multi-component crude was quantitatively characterized and the impacts of external conditions—including temperature and pressure—on the motion of the CO2 dissolution and diffusion coefficients were systematically investigated. Finally, the swelling behavior of mixed CO2–crude oil was analyzed and the diffusion coefficients were predicted; furthermore, the levels of CO2 impacting the oil’s mobility were analyzed. Results showed that temperature stimulation intensified molecular thermal motion and increased the voids between the alkane molecules, promoting the rapid dissolution and diffusion of CO2. This caused the crude oil to swell and reduced its viscosity, further improving the mobility of the crude oil. As the pressure increased, the voids between the internal and external potential energy of the crude oil models became wider, facilitating the dissolution of CO2. However, when subjected to external compression, the CO2 molecules’ diffusing progress within the oil samples was significantly limited, even diverging to zero, which inhabited the improvement in oil mobility. This study provides some meaningful insights into the effect of CO2 on improving molecular-scale mobility, providing theoretical guidance for subsequent investigations into CO2–crude oil mixtures’ complicated and detailed behavior.

Corrosion level estimation in reinforced concrete beams by acoustic emission sensing and selective crack measurements

AbstractAccurate corrosion assessment plays an important role in ensuring structural safety of reinforced concrete (RC) structures. However, on‐site assessment of existing concrete structures presents many challenges, including high costs, limited inspection timeframes, and difficult accessibility. To facilitate inspection‐based corrosion assessment, this paper presents a novel approach by combining short‐term acoustic emission (AE) monitoring with selective crack width measurements for corrosion level (CL) assessment. AE sensing is a monitoring technique which can detect ongoing internal degradation mechanisms by analyzing ultrasonic waves emitted by the damage process. Yet, two major challenges arise on site: (1) practical limitations prevent continuous AE monitoring over the structure's entire lifetime and (2) AE can only generate relative results in the absence of reference measurements. This paper addresses both challenges to bridge the gap between laboratory experiments and on‐site monitoring of corroding RC structures. First, short periods of AE monitoring data are analyzed to investigate the potential of AE sensing over limited timeframes. Second, AE data of corroding RC beams are combined with sparse crack width measurements in order to obtain absolute CLs. The proposed methodology is experimentally validated by corroding eight beams with varying dimensions, corrosion zones, and reinforcement layouts. The experimental results prove that the estimated CLs closely match the rebar mass losses, with a mean absolute error of 1.53% CL for beams reaching up to 14% CL, confirming the potential of the combined AE and crack width measurement technique as an efficient and accurate condition assessment approach. Moreover, AE sensing provides detailed spatial variability of the rebar corrosion in the monitored zone, which is challenging to obtain with conventional techniques. By using this dual‐technique approach, shorter monitoring periods prove nearly as effective as continuous AE monitoring in accurately estimating CLs.

Experimental Study on Human Kinetic Energy Harvesting with Wearable Lifejackets to Assist Search and Rescue

This study explores the integration of a human kinetic energy-harvesting mechanism into lifejackets to address the energy needs of aid search and rescue operations in aquatic environments. Due to the limited data on the movement patterns of drowning individuals, a human motion model has been developed to identify optimal design parameters for energy harvesting. This model is developed from computer vision analysis of underwater footage and motion capture laboratory experiments and is used to quantify the potential for power generation. The field testing experiment is conducted underwater, replicating the environment used for footage collection and analysis for the modelling. During the field testing, the participant wears a lifejacket integrated with the energy-harvesting device. Field testing data are then collected to verify the model. The efficacy of this approach is demonstrated with observed power outputs ranging from 0 mW to 754 mW in simulations and experiments. Despite challenges such as the “dead zone” in a drowning person’s motion, the success of the experiments underscores the potential of the proposed energy-harvesting mechanism to efficiently harness the kinetic energy generated by a drowning person’s movements. This study contributes to the development of sustainable, energy-efficient solutions for search and rescue operations, particularly in remote and challenging aquatic environments.

Synthesis, Copper Chelation, and Free Radical Scavenging Ability of Edaravone: An Undergraduate Medicinal Chemistry Laboratory Experiment

Synthesis, Copper Chelation, and Free Radical Scavenging Ability of Edaravone: An Undergraduate Medicinal Chemistry Laboratory Experiment

Inoculation with arbuscular mycorrhizal fungi improves plant biomass and nitrogen and phosphorus nutrients: a meta-analysis

Arbuscular mycorrhizal fungi (AMF) have profound effects on plant growth and nitrogen (N) and phosphorus (P) nutrition. However, a comprehensive evaluation of how plant N and P respond to AMF inoculation is still unavailable. Here, we complied data from 187 original researches and carried out a meta-analysis to assess the effects of AMF inoculation on plant growth and N and P nutrition. We observe overall positive effects of AMF inoculation on plant performance. The mean increases of plant biomass, N concentration, P concentration, N and P uptake of whole plant are 47%, 16%, 27%, 67%, and 105%, respectively. AMF inoculation induces more increases in plant concentrations and storage of P than N. Plant responses to AMF inoculation are substantially higher with single AMF species than with mixed AMF species, in laboratory experiments than in field experiments, and in legumes than in non-legumes. The response ratios of plant N and P nutrition are positively correlated with AMF colonization rate, N addition, P addition, and water condition, while unvaried with experiment duration. The biggest and smallest effect sizes of AMF inoculation on plant performance are observed in the application of nitrate and ammonium, respectively. Accordingly, this meta-analysis study clearly suggests that AMF inoculation improves both plant N and P nutrients and systematically clarifies the variation patterns in AMF effects with various biotic and abiotic factors. These findings highlight the important role of AMF inoculation in enhancing plant N and P resource acquisitions and provide useful references for evaluating the AMF functions under the future global changes.

Multifactorial Analysis of the Effect of Applied Gamma-Polyglutamic Acid on Soil Infiltration Characteristics

To investigate the mechanism and influence of applying gamma-polyglutamic acid (γ-PGA) on soil water infiltration, laboratory experiments and numerical simulations were conducted using Hydrus-1D. These studies assessed the impact of various application rates of γ-PGA on soil water characteristic parameters. Orthogonal simulation experiments on soil bulk density, γ-PGA application rates, and burial depths were performed utilizing predefined soil water characteristic values (twelve groups: nine groups of numerical simulation experiments and three groups of laboratory verification tests), and the soil infiltration characteristics were analyzed. Concurrently, an empirical model was developed to elucidate the relationships between the empirical model parameters and influencing factors, as well as to examine the sensitivity of these factors to changes in soil infiltration rate. The relationship between cumulative infiltration and the distance of wetting front movement, based on the water balance equation, was refined. The results indicated that γ-PGA significantly affected soil water characteristic parameters, where the saturated water content and the reciprocal of soil intake suction increased with rising γ-PGA applications (p < 0.01), while the saturated hydraulic conductivity and the parameter n decreased (p < 0.01), with no notable changes in the retained water content (p > 0.05). The trend in cumulative infiltration influenced by various factors could be modeled by a capacitive charging model function, which yielded a superior fit. A negative correlation existed between the sensitivity index and all the influencing factors (p < 0.05), with the order of influence being soil bulk density, γ-PGA application rate, and γ-PGA burial depth, respectively. Utilizing the modified water balance equation, the ratio of cumulative infiltration to wetting front migration distance corresponded more closely with a power function. These findings provide a theoretical foundation for further studies on the effects of γ-PGA on crop growth characteristics in fields and the optimization of γ-PGA technical element combinations.

The Rank Length Effect

Rank lists vary in the number of items ranked on the list (e.g., top 5 vs. top 20 movies on IMDb), that is, the rank length. Across ten studies, including both field and laboratory experiments, the authors examine the influence of rank length on evaluations, willingness to pay, and choice. They document a novel rank length effect: The same ranked items elicit more positive judgments when the rank length is longer (vs. shorter), although the differences in judgments between the ranked items are smaller. This effect is driven both by consumers’ tendency to narrowly focus on the rank list and by the manner in which they map the rank list onto their mental number line. The rank length effect extends to willingness to pay, and choice. The authors explore three different kinds of choice contexts, discuss implications, and offer suggestions for future research.

Ethanolamine ices: Experiments in simulated space conditions

Laboratory experiments on the interactions between complex organic molecules, interstellar dust, and ultraviolet (UV) radiation are crucial to understanding the physicochemical mechanisms that lead to the synthesis of the observed interstellar complex organic molecules (iCOMs), and to search for new molecular species not yet observed in the gas phase of the interstellar medium (ISM). We aim to study the role of a new, recently discovered interstellar molecule, ethanolamine (EtA, NH CH CH OH), in surface chemistry in the ISM. In the laboratory, thanks to a combination of temperature programmed desorption (TPD) experiments and electron ionization (EI) mass spectrometry analyses, we studied the thermal desorption of pure ethanolamine and its mixture with water from nanometric amorphous olivine grains cooled down to 10 K, with or without UV irradiation. Ethanolamine was found to be stable, even in the presence of water, when irradiated with UV light. The presence of olivine grains strongly modified the TPD curves, trapping the molecule up to about 295 K, meaning that the precursors of some biological molecules could be retained on the grains even in the innermost parts of protoplanetary disk. We then identified a series of products formed when the molecule was irradiated onto the dust substrate. Of particular interest is the fact that irradiation of ice containing ethanolamine, a molecule known to be present in the ISM, can produce more complex and astrobiologically interesting species. Furthermore, our results further our understanding of existing observational data.

Measuring the impact of concept knowledge and laboratory intervention on pre-service kindergarten teachers’ pedagogical content knowledge in science education

ABSTRACT K-12 science education is essential for cultivating students’ scientific talents, with teachers playing a critical role in this process. This study investigates the effects of conceptual knowledge and laboratory interventions on pre-service kindergarten teachers’ pedagogical content knowledge (PCK), deriving water as a topic for science activities. Thirty-three pre-service teachers were divided into three groups: Group 1 received lectures on science knowledge, Group 2 participated in lectures supplemented by laboratory experiments, and the third group served as the control group. A mapping approach is utilized to assess the development of PCK among participants. The results revealed that both intervention groups demonstrated significantly improved PCK compared to the control group (p < 0.001). However, no significant difference was observed between the two intervention groups regarding PCK enhancement. Based on these results, we argue the importance of cultivating scientific content knowledge among pre-service education students. Additionally, the science curriculum for these students should differ from common STEM programs, focusing more closely on the scientific knowledge and inquiry skills they will need in their future teaching.

Efficacy of Green and Chemically Synthesized Nano Boron Nitride on Sunflower Germination

ABSTRACTThis study explores the eco‐friendly synthesis of nanoparticles using natural sources, specifically employing Cassia fistula leaf extract for the production of boron nitride nanoparticles. Characterization of the synthesized nanoparticles was performed using Raman spectroscopy and UV‐visible spectroscopy to identify functional groups. Ab initio studies were conducted to investigate the electronic properties of the boron nitride nanostructures. The structural analysis through powder x‐ray diffraction confirmed a hexagonal configuration of the nanoparticles. Scanning electron microscopy and transmission electron microscopy revealed particle sizes below 100 nm. Laboratory experiments demonstrated that sunflower seeds treated with 1500 ppm of green‐synthesized nano boron nitride achieved the highest germination rate of 98.2%, surpassing other concentrations and chemically synthesized nanoparticles, which reached 93.9% at 2000 ppm. The control treatment yielded a germination rate of 76.2%. The eco‐friendly synthesized nanoparticles exhibited superior efficacy compared to both chemically synthesized nanoparticles and conventional fertilizers.

From the lab to the field and back: the effects of need satisfaction on reconciliation among Germans and Israelis.

Previous lab experiments supported the needs-based model of reconciliation, which posits that discussing historical transgressions enhances the need for acceptance in groups perceived as perpetrators and empowerment in groups perceived as victims. Addressing these needs (e.g., through accepting or empowering messages from outgroup members) increases willingness to reconcile. This study tests this model in a real-world settings. Study 1 examined 143 German and Israeli Jewish participants from youth exchange programs, measuring their feelings of acceptance/empowerment, program satisfaction, outgroup attitudes, and keeping in touch with outgroup members. Study 2 examined 293 Israeli Jews, manipulating the salience of the conflict between Israelis and Palestinians in a pre-registered laboratory experiment and measuring responses to accepting versus empowering messages from Germans. As expected, Study 1 (N =143) found Germans' feelings of acceptance were linked to program satisfaction, positive outgroup attitudes, and keeping in touch. For Israeli Jews, feelings of empowerment were linked to satisfaction and positive attitudes, but keeping in touch was unexpectedly linked to acceptance. This unexpected effect maybe because keeping in touch is done mainly through social networks that focus on the conflict between Israelis and Palestinians, often with a focus on Israel's transgressions against Palestinians. Consistent with this explanation, Study 2 (N=293, pre-registered) showed that Israeli Jews viewed accepting messages from Germans as more conciliatory when presented with transgressions against Palestinians, and empowering messages as more effective when presented with reminders of historical victimization by Nazis. The findings from Study 1 partially support the needs-based model of reconciliation and additionally suggest that reconciliation needs vary with context. Implications for people-to-people peace-building interventions are discussed.

Pollination‐related plant traits under environmental changes: Seasonal and daily mismatches produce temporal constraints

Abstract Pollination is a key tenet of ecosystem sustainability and food security, but it is threatened by climate change. While many studies investigated the response of plant‐pollination traits to temperature, few attempted multifactorial and integrative approaches with multiple floral traits. We determined which plant‐pollination traits were disrupted by environmental changes and the consequence for plant fitness. We focused on the thermogenic plant, Arum italicum, which relies on floral scent and heat production to attract its pollinators with a deceptive strategy. In a field mesocosm, we measured the response of floral phenology, thermogenesis traits, scent and plant fitness to experimental changes in shade level, water supply and soil temperature. In the laboratory, we exposed plants to extreme heat to determine the thermoregulation ability at high temperatures. Plant fitness decreased dramatically in response to soil warming and the level of shade. While both factors caused a lower number of inflorescences, soil warming was mostly responsible for the crash in number of fruits. The plant traits related to thermogenesis and scent were relatively resilient to the environmental changes in the mesocosm and were unlikely to produce the observed decrease in plant fitness. First, environmental changes only weakly modified the scent composition. Second, the appendix regulated its maximal temperature almost perfectly, while stamen regulated imperfectly. In the laboratory experiment, the appendix maintained a thermal gradient supposedly to improve scent emission while stamen became cooler than ambient air, possibly preventing the pollinators from overheating within the floral chamber. By contrast, the phenology of flowering was drastically modified. Flowers appeared earlier in the season in response to soil warming (by 39 days) or absence of shade (by 19 days). At the daily scale, flowering hour did not change across the season resulting in plants flowering before sunset late in the season and before the pollinator activity window (mostly nocturnal). The strong shift observed in the flowering period may induce a temporal mismatch with this pollinator both early and late in the season when the insects may not be active so early in the spring and during daytime, respectively, thereby altering plant fitness. Read the free Plain Language Summary for this article on the Journal blog.

Laboratory and numerical investigations on land-sourced solute transport in coastal fractured aquifers

Land-based pollutants threaten coastal aquifers, highlighting the need to protect groundwater and nearshore marine ecosystems. While aquifer heterogeneity has been recognized as a significant factor affecting solute behavior, the impact of fractures on land-sourced solute transport in coastal aquifers remains unclear. This study attempted to address this issue through laboratory experiments and discrete fracture matrix (DFM) models. The impact of horizontal fractures on the temporal and spatial characteristics of solute transport, spreading, and discharge under seawater intrusion was analyzed based on variations in fracture position and length. The results show that fractures/low-velocity zones (LVZ) can accelerate/delay solutes, dividing them into different transport modes and enhancing/prolonging their spreading/discharge duration. Changes in fracture position and length also affect its transport acceleration and path deviation abilities, which ultimately determine when solute discharge occurs. The mixing zone and unsaturated zone, in addition to the LVZ, hinder solute transport, reducing the rate and delaying the end of solute discharge. Meanwhile, fractures facilitate solute transport into the saltwater wedge, expanding the solute discharge zone. However, if solutes are initially within the LVZ, their entry into the fracture rely on their distance from the fracture's near-land edge and the size of the fracture's convergence zone.

Discrete element model of low-velocity projectile penetration and impact crater on granular bed

The present study investigates the low-velocity impacts of a spherical projectile into a bed of spherical particles using Discrete Element Method (DEM) simulations and laboratory experiments. The findings reveal intricate forces and energy transformations, indicating the phenomena leading to projectile impact, penetration, cessation, and crater formation. The DEM result indicates that the penetration stopping time of the projectile is not influenced by impact velocity. Further, simulations show that projectile penetration depth correlates with 1/2.7 power of total impact height, while crater diameter and depth scale with 1/4.32 power of nondimensional impact energy. The shape of the resulting crater appears independent of impact velocity and the maximum diameter of the fluidized region varies with the 1/2.68 power of impact velocity. Experimental validation confirms the accuracy of predicted penetration depths and crater diameters, enhancing confidence in DEM simulations. These findings extend scaling laws and reveal the influence of larger particles on low-velocity impact dynamics, addressing unexplored aspects of granular cratering.

Exploring the impact of sepak takraw ball heading on brain injury risk: An analytical and experimental investigation

Sepak takraw, a unique sport resembling volleyball but played with the legs, is popular in Asia. Players often use their foreheads to receive the ball, exposing them to potential brain injuries. This research evaluates the potential for brain injuries from heading in sepak takraw. Using both analytical and experimental approaches, we developed a mathematical model adapted from soccer-related studies to predict peak linear acceleration (PLA). We also conducted laboratory experiments to measure PLA and peak rotational acceleration (PRA) using a ball launcher and an Anthropomorphic Test Device (ATD). The mathematical model demonstrated a high level of accuracy in PLA prediction, confirming its reliability. Comparative analysis with soccer and water polo studies revealed that the measured PLA, PRA, and Head Injury Criteria (HIC) values for sepak takraw are below suggested concussion thresholds, indicating a lower risk of brain injury. However, this assessment does not account for the cumulative effects of repetitive head impacts, which increase the risk of brain injury over time. Despite sepak takraw’s distinct play style, the findings indicate that while the inherent risk of head injury from single impacts may be low, the potential long-term effects of repetitive impacts warrant further investigation. This study enhances the understanding of sports-related brain injuries and highlights the need for further research into subconcussive impacts and the development of protective measures. Our research paves the way for more comprehensive investigations, including field experiments, which are crucial for a nuanced understanding of sepak takraw’s impact dynamics.

Therapeutic Potential of Quercetin and their Compound Against Ovarian Cancer: New Approaches &amp; Application

Ovarian cancer is an exceptionally perilous form of cancer as it develops within the female reproductive system. Finding effective therapy platforms for ovarian cancer has been difficult because to the diverse array of molecular pathways and genetic alterations involved in its development. Therefore, it is imperative to discover novel therapeutic methodologies and advance their development. Medicinal herbs possess the capacity to independently or in combination with other pharmaceuticals, effectively treat malignancies such as ovarian cancer. Quercetin possesses remarkable anti-inflammatory and anti-cancer properties, making it one among numerous natural compounds with such qualities. Quercetin has demonstrated cytotoxicity against ovarian cancer cells in both laboratory experiments (in vitro) and live animal tests (in vivo). The potential anti-cancer effects of quercetin, particularly in relation to ovarian cancer, have not been extensively studied in human trials, despite encouraging findings from laboratory and animal experiments. Hence, it seems that quercetin could potentially be utilized in clinical trials as a therapeutic agent, either on its own or in conjunction with other chemotherapeutic drugs. This article will outline the primary aspects of quercetin's anti-cancer characteristics and thereafter concentrate on its application in the treatment of ovarian cancer.

Efficient Estimation of Synthetic Indicators for the Assessment of Nonlinear Systems Quality

The availability of synthetic indicators of the degree and type of nonlinearity in systems is used in various fields to assess system quality or to highlight possible malfunctions. Different distortion or damage indexes are synthetic measures designed (and standardized) to evaluate the frequency trend of specific aspects resulting from the nonlinear behavior of the system under consideration. The different measures of deviation from linear behavior quantitatively consider the system and its nonlinearity characteristics; they were defined according to practically feasible measurement methodologies and the various aspects of the system’s nonlinearity that needed to be highlighted. In parallel, techniques for representing and modeling nonlinear systems have been defined, capable of describing the system in a more general way, attempting to capture its input–output characteristics by varying the level of stress to which the system is subjected. Numerous modeling techniques have been proposed, aimed at representing the nonlinear behavior of physical devices. In this paper, after an extensive description of the Hammerstein model identification technique based on swept sinusoidal signals, we show how the nonlinear model of the system can be used to obtain accurate estimates of the parameter aimed at describing the nonlinearity characteristics of the system. This extensive description makes it possible to point out that the same Hammerstein model can be obtained not only from a single type of excitation, but it is shown that the identification technique can be extended to input signals of different types. The description of the method also makes clear the motivation behind the introduction of the proposed original technique for estimating, from a single measurement, the model parameters of the nonlinear system—and from these the synthetic estimators—relative to multiple values of the input signal amplitude, thus enabling a considerable increase in the estimation efficiency of these parameters. The proposed technique is verified with both synthetic and laboratory experiments, demonstrating the effectiveness of the method in evaluating nonlinear system parameters, distortion estimates, and parameters defined for an early detection of defects of the structure.

The efect of low-dose gamma radiation on the development of plants from irradiated Pisum sativum sprouts in laboratory experiments

The problem of radiation exposure to organisms is relevant for areas where nuclear industry enterprises are located. Plant biotests are widely used for biotesting of anthropogenic factors affecting the environment, including radiation. The sensitivity of growth and cytogenetic parameters of the biotest based on Pisum sativum to the action of gamma irradiation n has been shown before, but only at high doses. The purpose of this work was to evaluate the influence of low-dose gamma irradiation on the development of Pisum sativum over 6-10 days after irradiating the sprouts. In the experiments, seeds of the Radomir sowing variety from the collection of the pea breeding laboratory of Krasnoyarsk Research Institute of Agriculture - Federal Research Centre Krasnoyarsk Scientific Center SB RAS were used. Pea sprouts were irradiated with a 137Cs source for 24 and 72 hours, with the absorbed dose being 20 and 62 mGy. After irradiation, the sprouts were grown in a climatic chamber on hydroponics for 10 days (240 hours). The control consisted of non-irradiated sprouts grown under identical conditions. The experiments for the first time provided reliable data on the negative effects of gamma irradiation (20 and 62 mGy) on the development of sowing peas 6-10 days after irradiation. A negative effect of gamma irradiation on the growth of the main and lateral roots of young plants was revealed. The experiments with irradiated pea sprouts confirmed the previously known fact that plant roots are more sensitive to irradiation compared to shoots. The pattern of change in the length of the main root of peas over time during germination at a dose of 20 mGy is described by a linear equation, while for a higher dose of irradiation, 62 mGy, the data can be approximated by a logarithmic equation with saturation. The different character of root length dependence on the time of cultivation after irradiation indicates a possible trend in plant growth under various doses of irradiation and cultivation times.

Alterations in the Renin-Angiotensin System in Experimental Septic Shock.

To analyze dynamic changes in the renin-angiotensin system (RAS) during septic shock, focusing on angiotensin-converting enzyme (ACE) activity and the balance between angiotensin peptides, using a mass spectrometry method. Experimental septic shock model induced by peritonitis in swine. Experimental Laboratory, Department of Intensive Care, Erasme Hospital, Université Libre de Bruxelles. Forty time points from eight mechanically ventilated pigs. Septic shock was induced using intraperitoneal instillation of autologous feces, followed by standardized fluid resuscitation, norepinephrine infusion, antibiotic administration, and peritoneal lavage. The induction of sepsis resulted in a significant increase in plasma renin activity and levels of angiotensin I and II, with a significant decrease in ACE activity observed from 4 hours post-resuscitation and a notable rise in the angiotensin I/angiotensin II ratio at 12 hours. Additionally, a shift toward the angiotensin-(1-7) axis was observed, evidenced by an increased angiotensin-(1-7)/angiotensin II ratio. The study highlighted dynamic shifts in the RAS during septic shock, characterized by reduced circulating ACE activity, elevated angiotensin I/II ratio, and a shift toward the angiotensin-(1-7) axis. These findings suggest an adaptive response within the RAS, potentially offering new insights into sepsis management and therapeutic targets.

Study on the characteristics particles of coarse grain material in high bench dump

Particle shape is an important factor affecting the strength and deformation of coarse materials in dumps. However, conducting research on particle shape in current laboratory experiments, and there exists no classification standard for the particle shape of the dump. Considering the project on high-bench dump in Jiangxi Province, based on the random particle construction method, this study determined the characteristic particles of coarse grain material in the dumping site by combining field investigation results, large-scale direct shear tests, and numerical analysis. Further, the influence mechanism of coarse grain content and characteristic particles on the mechanical characteristics of the dump were analyzed. The results showed that the increase in coarse grain content enhanced the irregularity of particle shape, increased the internal friction angle between particles, and reduced the cohesion of the dump. Moreover, with increase in the normal stress, the shear strength changed from insignificant to gradually enhanced, although the increasing trend slowed down. The constructed random particle model can well solve the effects of occlusion, nesting, and friction between particles that is neglected by the standard spherical particle model, and the fitting degree is better. The particle characteristics of coarse-grain materials in the dump were primarily block, strip, and flake. The three types of shape characteristics under low normal stress did not affect the mechanical properties of the dump. Further, with the increase in normal stress, the stress-strain curve reflected the shape characteristics and content of the dominant characteristics in the dump. Specifically, the block sample exhibited the dominant characteristics and the most content under the same normal stress, followed by the strip sample, with the flake sample exerting the least influence. The research results provide a theoretical basis for long-term safe operation, disaster monitoring, and early warning of high bench dump.