Search Results (2,556)

Cold-bonded (CB) fly ash aggregate, an eco-friendly material derived from industrial by-products, is used to fully replace natural coarse aggregate in producing lightweight concrete (LWC-CB). This study systematically investigates the post-high-temperature mechanical properties and damage mechanisms of LWC-CB. Specimens exposed to ambient temperature (10 °C) and elevated temperatures (200 °C, 400 °C, 600 °C) underwent cubic compression tests, with surface deformation monitored via digital image correlation (DIC). Experimental results indicate that the strength retention of LWC-CB is approximately 6% superior to ordinary concrete below 500 °C, beyond which its performance converges. Damage analysis reveals a transition in failure mode: at ambient temperature, shear failure is governed by the low intrinsic strength of CB aggregates, while after high-temperature exposure, damage localizes within the mortar and the interfacial transition zone (ITZ) due to mortar micro-cracking and thermal mismatch. To elucidate these mechanisms, a three-dimensional mesoscale model was developed and validated, effectively characterizing the internal multiphase structure at room temperature. Furthermore, a homogenization model was established to analyze the macroscopic thermo-mechanical response. The numerical simulations show strong agreement with experimental data, with a maximum deviation of 15% at 10 °C and 3% after high-temperature exposure, confirming the model’s accuracy in capturing the performance evolution of LWC-CB. Full article

The paper proposes an optimization procedure for maximizing the resistance of composite plates exposed to impact loads. For a composite plate with a predefined composite material, number, and thickness of layers, the set objective is to find the optimal solution in terms of the layer orientation so as to withstand the impact test. The fiber orientation angle is treated as a continuous design variable within the context of the problem. The commercially available finite element software package Abaqus is used to model a Kevlar 49/Epoxy composite plate and simulate its mechanical behavior when exposed to an impact load. As this deals with a highly dynamic process that involves significant nonlinear effects, an explicit time-integration scheme is selected. Prediction of the plate damage based on its maximum stress failure criteria is used as the objective function for optimization, whereas the penetration analysis is based on the Hashin criteria and implemented in an Abaqus VUMAT subroutine. The obtained results are expected to be of interest to ballistic vest manufacturers to develop passive protection solutions. Full article

Blast damage to structural members poses serious risks to both buildings and people, making it important to understand how these elements behave under extreme loads. Columns in reinforced concrete (RC) structures are especially critical, as their sudden failure can trigger progressive collapse, unlike beams or slabs that have more redundancy. This state-of-the-art review brings together the current knowledge of the blast response of RC columns, focusing on their failure patterns, dynamic behavior, and key loading mechanisms. The studies covered include experiments, high-fidelity numerical simulations, emerging machine learning approaches, and analytical models for columns of different shapes (square, rectangular, circular) and strengthening methods, such as fiber reinforcement, steel-concrete composite confinement, and advanced retrofitting. Composite columns are also reviewed to compare their hybrid confinement and energy-absorption advantages over conventional RC members. Over forty specific studies on RC columns were analyzed, comparing the results based on geometry, reinforcement detailing, materials, and blast conditions. Both near-field and contact detonations were examined, along with factors like axial load, standoff distance, and confinement. This review shows that RC columns respond very differently to blasts depending on their shape and reinforcement. Square, rectangular, and circular sections fail in distinct ways. Use of ultra-high-performance concrete, steel fibers, steel-concrete composite, and fiber-reinforced polymer retrofits greatly improves peak and residual load capacity. Ultra-high-performance concrete can retain a significantly higher fraction of axial load (often >70%) after strong blasts, compared to ~40% in conventional high-strength RC under similar conditions. Larger sections, closer stirrups, higher transverse reinforcement, and good confinement reduce spalling, shear failure, and mid-height displacement. Fiber-reinforced polymer and steel-fiber wraps typically improve residual strength by 10–15%, while composite columns with steel cores remain stiff and absorb more energy post-blast. Advanced finite element simulations and machine learning models now predict displacements, damage, and residual capacity more accurately than older methods. However, gaps remain. Current design codes of practice simplify blast loads and often do not account for localized damage, near-field effects, complex boundary conditions, or pre-existing structural weaknesses. Further research is needed on cost-effective, durable, and practical retrofitting strategies using advanced materials. This review stands apart from conventional literature reviews by combining experimental results, numerical analysis, and data-driven insights. It offers a clear, quantitative, and comparative view of RC column behavior under blast loading, identifies key knowledge gaps, and points the way for future design improvements. Full article

Cyclic dynamic loading significantly influences the dynamic mechanical properties of cemented tailings backfill (CTB). This study investigates the dynamic mechanical properties and mesoscopic characteristics of CTB under cyclic dynamic loading. Using a Split Hopkinson Pressure Bar (SHPB) system, impact tests were conducted on CTB specimens subjected to varying numbers of cyclic impacts. The dynamic peak compressive strength (DPCS), elastic modulus, energy evolution, and failure modes were analyzed. Additionally, computed tomography (CT) scanning and 3D reconstruction techniques were employed to examine the internal pore and crack distribution. Results indicate that cyclic impacts lead to a gradual reduction in DPCS and energy absorption capacity, while the elastic modulus shows strain-rate dependency. Mesostructural analysis reveals that cyclic loading promotes the initiation and propagation of microcracks. This study establishes a correlation between mesoscopic damage evolution and macroscopic mechanical degradation, providing insights into the durability and stability of CTB under repeated blasting disturbances in mining environments. Full article

Mycotoxins are toxic secondary metabolites produced by filamentous fungi that contaminate agricultural commodities, posing risks to food safety, animal productivity, and human health. The gastrointestinal tract is the first and most critical site of exposure, where the intestinal epithelium functions as both a physical and immunological barrier against luminal toxins and pathogens. While extensive research has demonstrated that mycotoxins disrupt epithelial integrity through tight junction impairment, oxidative stress, apoptosis, and inflammation, their effects on the intestinal stem cell (ISC) compartment and epithelial regeneration remain insufficiently understood. This review integrates recent findings from in vivo, cell culture, and advanced 3D intestinal organoid and gut-on-chip models to elucidate how mycotoxins such as deoxynivalenol and zearalenone impair ISC proliferation, alter Wnt/Notch signaling, and compromise mucosal repair. We also discuss dose relevance, species differences, and the modulatory roles of the microbiome and short-chain fatty acids, as well as emerging evidence of additive or synergistic toxicity under co-exposure conditions. By bridging well-established mechanisms of barrier disruption with the emerging concept of ISC-driven regenerative failure, this review identifies a critical knowledge gap in mycotoxin toxicology and highlights the need for integrative models that link epithelial damage to impaired regeneration. Collectively, these insights advance understanding of mycotoxin-induced intestinal dysfunction and provide a foundation for developing nutritional, microbial, and pharmacological strategies to preserve gut integrity and repair. Full article

To investigate the influence mechanism of hanger damage and arch-beam combined parameters on the failure behavior of tied-arch bridges, this study employs an advanced damage failure model within the LS-DYNA. A comprehensive simulation of the entire failure process was conducted, considering the coupled effects of hanger damage parameters and structural parameters of the arch-beam system, using a tied-arch bridge as the engineering case. The primary innovation of this study lies in overcoming the limitations of previous research, which has largely been confined to single hanger failure or static parameter analysis, by achieving, for the first time, dynamic tracking and quantitative identification of structural failure paths under the coupled influence of multiple parameters. The results demonstrate that both the severity and spatial distribution pattern of hanger damage significantly influence the structural failure mechanism. When damage is either uniformly distributed across the bridge or relatively concentrated—particularly when long hangers experience severe degradation—the structure becomes susceptible to cascading stress redistribution, substantially increasing the risk of global progressive collapse. This finding provides a theoretical foundation for developing risk-informed maintenance and repair strategies for hangers. It is therefore recommended that practical maintenance efforts prioritize monitoring the condition of long hangers and regions with concentrated damage. Furthermore, variations in arch-beam combined parameters are shown to have a significant effect on the structure’s collapse resistance. For the case bridge studied herein, the original design parameters achieve an optimal balance between anti-collapse performance and economic efficiency, underscoring the importance of rational parameter selection in enhancing system robustness. This work offers both theoretical insights and numerical tools for evaluating and optimizing the collapse-resistant performance of under-deck tied-arch bridges, contributing meaningful engineering value toward improving the safety and durability of similar structures. Full article

Steel structure specimens exhibit high strength and ductility and are often subjected to complex loading conditions and pre-existing cracks in critical engineering applications. In this study, peridynamics (PD) theory—known for its unique advantages in modeling structural damage and failure—is employed to establish specimens with bilateral cracks and double central cracks at varying longitudinal spacings. To address the complexity of elastic–plastic behavior, the D-M model is applied to transform the nonlinear problem into an equivalent linear elastic one. This approach is integrated with PD theory and the crack tip opening displacement (COD) concept of fracture mechanics to derive a novel linear fracture criterion, termed the PD-COD. Furthermore, numerical models based on PD and the PD-COD criterion are developed for central cross double-crack specimens, enabling analysis of crack propagation under loading. The results validate the effectiveness of the PD-COD damage criterion and elucidate the underlying mechanisms of crack propagation in centrally intersecting double-crack configurations. This work contributes to a deeper understanding of the damage evolution in defective steel structures under load and provides theoretical guidance for engineering design. Full article

To investigate the bending performance and damage characteristics of segmental joints with double sealing gaskets in large-diameter shield tunnels under high water pressure, this study established a three-dimensional high-fidelity numerical model of the segment-joint system based on the Pearl River Estuary Tunnel project. A comprehensive analysis was conducted on the mechanical and deformation behavior of large-diameter shield tunnel segmental joints under combined compressive/flexural loading. The research systematically examined the evolving relationships between bending moments, vertical displacements, and joint opening at the double-sealed gasketed joints under varying axial compression conditions, thereby elucidating the phased characteristics of joint deformation. The results indicate that the deformation patterns of double-sealed gasketed segmental joints under compressive/flexural loading exhibit pronounced nonlinearity and stage-dependent features. Both positive and negative bending moment scenarios demonstrate four distinct failure phases. Under high-water-pressure conditions, structural damage initiation consistently occurs at waterproof sealing grooves and bolt holes, regardless of bending moment direction. As loading intensifies, cracks propagate symmetrically at 45° angles from the joint interface, generating extended fracture networks, which creates additional water infiltration pathways, significantly compromising the joint’s waterproofing integrity. Full article

Macroscopic fatigue tests, mesoscopic finite element simulations, and microscopic molecular dynamics simulations were composed to study the damage and failure of drainage asphalt mixtures in multiscale. The applicability of the fatigue models fit by strain, stress, and the linear fitting slope of the indirect tensile modulus curves were compared. The mesoscopic damage and failure distribution and evolution characteristics were studied, considering the single or coupling effect of traffic loading, hydrodynamic pressure, mortar aging, and interfacial attenuation. The microscopic molecular mechanism of the interface adhesion failure between the aggregate and mortar under water-containing conditions was analyzed. Results show that the fatigue model based on the linear fitting slopes of the indirect tensile modulus curves has significant applicability for drainage asphalt mixtures with different void rates and gradations. The damage and failure have an obvious leap development when traffic loading increases from 0.7 MPa to 0.8 MPa. The hydrodynamic pressure significantly increases the stress of the mortar around the voids and close to the aggregate, promoting damage development and crack extension, especially when it is greater than 0.3 MPa. With the aging deepening of the mortar, the increase rate of the damage degree gradually decreases from the top to the bottom of the mixture. With the development of interfacial attenuation, the damage and failure of interfaces continue increasing, while that of the mortar increases first and then decreases, which is related to the loading concentration in the interface and the stress decrease in the mortar. Under the coupling effects, whether the cracks mainly generate in the mortar or interface depends on their damage degrees, thus causing the stripping of the aggregate wrapped or not wrapped by the mortar, respectively. The van del Waals force is the main molecular effect of interface adhesion, and both acidic and alkaline aggregate components significantly tend to form hydrogen bonds with water rather than asphalt, thus attenuating the interface adhesion. Full article

Changes in the homeostatic balance between purine nucleotide synthesis, degradation, and salvage are caused by disruptions in ATP supply and/or demand in the heart. These disruptions may affect myocardial energetics and, consequently, cardiac function and mechanics. Increased cardiac inorganic phosphate levels and decreased myocardial ATP levels are the outcomes of this decrease in purine nucleotide levels. Both modifications can immediately affect cellular mechanical work and tension development. Depletion of cardiac nucleotides and compromised myocardial mechanical function are linked to both acute myocardial ischemia and decompensatory remodelling of the myocardium in heart failure. Theoretically, in both acute ischemia and chronic high-demand situations associated with the development of heart failure, an imbalance in the breakdown, salvage, and synthesis of purine nucleotides results in a net loss of purine nucleotides. It was found that the use of nucleotide precursors can be a potentially effective approach to diminishing ischemia–reperfusion damage. The scope of this article is to review knowledge of the effect of purine nucleotide precursors such as D-ribose, AICAR, inosine, hypoxanthine, and adenine on myocardial ischemia–reperfusion injury and highlight potential targets for treating myocardial metabolic and mechanical dysfunction associated with ischemia–reperfusion injury by these molecules. Full article

Mechanical ventilation is a critical intervention in patients who cannot spontaneously maintain adequate oxygenation and remove carbon dioxide. However, it can also lead to severe lung injury via volutrauma, barotrauma, atelectrauma and biotrauma, and it can worsen existing lung disease such as acute respiratory distress syndrome. Ventilator-associated lung injury, the clinical manifestations of lung damage associated with mechanical ventilation, can trigger systemic inflammatory cascades that contribute to multi-organ failure. The utilization of lung-protective ventilation strategies helps to minimize further injury to the lungs during mechanical ventilation and improve survival rates. This review discusses the pathophysiology of ventilator-associated lung injury, including cellular and molecular responses, its systemic effects, risk factors, clinical presentation and diagnosis, protective strategies, and emerging therapies. It incorporates interdisciplinary advances, from novel pharmacologic and stem-cell therapies coupled with artificial intelligence and machine learning systems to provide a framework for the prevention of ventilator-associated lung injury that moves beyond purely mechanical considerations. Full article

The advancing speed of the coal mining face has a significant impact on the mining-induced stress and energy accumulation of the surrounding rock. To explain the influence mechanism from a mesoscopic perspective, this study conducted a uniaxial compression test on the coal–rock combination body under different quasi-static loading rates, and analyzed their mechanical properties, failure characteristics, acoustic emission characteristics and energy evolution characteristics. The main findings are as follows: The uniaxial compressive strength and elastic modulus of the coal–rock combination body show a variation law of first increasing and then decreasing with the increase in loading rate, while the degree of impact failure significantly increases gradually as the loading rate rises. With the increase in loading rate, there is a tendency that the AE parameters concentrate from the first two stages to the latter two stages. The post-peak residual elastic energy density of the coal–rock combination body increases gradually with the increase in loading rate. The formation of the advancing speed effect of mining-induced stress concentration and elastic energy accumulation in coal–rock masses is caused by the “competitive” interaction between fracture propagation and coal matrix damage when the coal component in the coal–rock combination is deformed under stress. Full article

The reliability of ocean-going ship engine fuel systems is crucial for the safety and continuous operation of vessels. Failure of this system can lead to serious operational and economic consequences; therefore, effective diagnostics and failure prediction are essential elements of modern fleet management. This paper presents an analysis of the reliability of fuel systems based on operational data from ten bulk carriers operated by Polska Żegluga Morska in Szczecin. The analysis combined classical statistical methods with artificial intelligence algorithms to develop a hybrid diagnostic and forecasting framework. The Weibull lifetime distribution was applied to estimate time-to-failure parameters, revealing mixed failure mechanisms—random failures (k < 1) and aging-related processes (k > 1). Using the k-means algorithm, ships were automatically classified into two reliability groups: high-failure-rate units and stable operational vessels. Individual linear regression models were then developed for each ship to forecast the time to the next failure, achieving satisfactory predictive performance (R² > 0.75 for most vessels). Sensitivity analysis quantified model robustness under different disturbance scenarios, yielding mean Relative Prediction Deviation (RPD) values of approximately 65% for Missing Data, 60% for False Failure, and 26% for Data Noise. These results confirm that the proposed hybrid reliability–AI framework is resistant to random noise but sensitive to incomplete or erroneous historical data. The developed approach provides an interpretable and effective tool for predictive maintenance, supporting reliability management and operational decision-making in marine engine systems. The article presents a hybrid model that has been developed to enable the detailed characterization of emergency processes and the identification of the most important factors that influence damage forecasting. For systems with variable failure risk, it was found that both classical probabilistic models and machine learning methods must be considered to interpret damage patterns correctly. Implementing data filtration and validation procedures before using data in artificial intelligence models has been shown to improve forecast stability and increase the usefulness of forecasts for planning repairs. Full article

Diabetes mellitus (DM) is a global health challenge that contributes to numerous complications. As a chronic metabolic disorder, DM leads to persistent microvascular and macrovascular damage, ultimately impairing the function of multiple organ systems. Cardiovascular diseases (CVD), including heart failure (HF), are among the most serious diabetes-related outcomes, accounting for substantial morbidity and mortality worldwide. Traditionally, diabetic HF has been attributed to coexisting conditions such as hypertensive heart disease or coronary artery disease. However, a high prevalence of HF is observed in individuals with DM even in the absence of these comorbidities. In recent years, the phenomenon of diabetes-induced HF has attracted considerable scientific interest. Gaining insight into the mechanisms by which diabetes elevates HF risk and drives key molecular and cellular alterations is essential for developing effective strategies to prevent or reverse these pathological changes. This review consolidates current evidence and recent advances regarding the cellular and molecular pathways underlying diabetes-related HF. Full article

Autoclaved lightweight concrete (ALC) exhibits considerable potential as a wall material in prefabricated structures, but its high water absorption and limited mechanical properties limit its widespread application. Ultra-high-performance concrete (UHPC), which possesses superior mechanical strength and durability, presents a promising reinforcement strategy. This study proposes the development of a UHPC-ALC composite wall material to enhance structural performance. The effects of shrinkage-reducing agent (SRA) content and expansive agent (EA) dosage on UHPC properties were systematically investigated. Results indicate that increasing SRA content improves the fluidity of UHPC and significantly reduces early autogenous shrinkage while the optimal EA dosage enhances both its mechanical properties and volume stability. Furthermore, an interfacial agent was employed to enhance the bonding performance between UHPC and ALC resulting in an average bonding strength of 0.93 MPa which represents a 675% increase compared with the untreated group. Finite element simulations and mechanical tests revealed that the composite material demonstrates a compressive strength of 11.2 MPa and a flexural strength of 6.8 MPa which corresponds to increases of 111.3% and 325%, respectively, relative to monolithic ALC. The composite demonstrated ductile failure and the experimental damage modes were consistent with those of the simulation results. This study offers guidance for optimizing UHPC-based composite wall materials via the multi-scale regulation of shrinkage behavior, interfacial properties, and structural design. Full article