Search Results (2,345)

In cold-region engineering, freeze–thaw (F–T) cycles act as a critical stressor on soil stability, where the recurring transition between frost heave and thaw settlement can drastically alter geotechnical properties and threaten long-term structural integrity. Yet, while the static characteristics of frozen soils are well documented, the dynamic impact of repetitive thermal cycling on long-term soil behavior remains a significant and relatively underexplored challenge in the field. This study investigates the effectiveness of polypropylene fiber (FPP) as a sustainable and environmentally benign reinforcement for high-plasticity clay. The research examines FPP’s influence on stress–axial strain relationships (unconsolidated undrained (UU) compressive strength) and its ability to mitigate frost heave and volumetric changes during F–T cycles. Laboratory-prepared FPP–clay samples were subjected to ten closed-system F–T cycles and tested using a UU triaxial machine. Results showed a 51% decrease in UU strength for unreinforced samples after ten cycles, while samples reinforced with 1% FPP exhibited only an 18.4% reduction. FPP reinforcement reduced frost heave and thaw settlement by 30% and significantly enhanced UU strength, increasing it by 60% before F–T cycles and 167% after exposure. The findings highlight FPP’s effectiveness in improving soil strength, minimizing volumetric changes, and mitigating frost-related damage, making it a viable solution for enhancing soil performance in cold regions. Full article

Light availability is a key environmental factor influencing plant functional traits and ecological strategies. To investigate how natural populations of Iris pumila respond to contrasting irradiance, we conducted an in situ reciprocal transplant experiment using clonal genotypes from two natural populations, each originating from an open dune and a shaded forest habitat. Leaves collected from each of the replanted and transplanted genotypes were analyzed for structural (specific leaf area—SLA, leaf dry matter content—LDMC), physiological (specific leaf water content—SLWC, photosynthetic pigments) and biochemical (peroxidase—POD, glutathione reductase—GR, phenolics and anthocyanins) traits. Shade-grown individuals developed thinner leaves with higher SLA and chlorophyll content, enhancing light-harvesting efficiency, whereas sun-exposed plants exhibited greater LDMC, increased POD and GR activities and higher anthocyanin levels—traits consistent with enhanced photoprotection under high irradiance. All genotypes exhibited pronounced plasticity to light intensity, with habitat exerting a stronger influence on trait expression than population origin. To evaluate oxidative balance, we proposed the ODAC index (Oxidative Damage to Antioxidant Capacity), which integrates lipid peroxidation with antioxidant capacity. ODAC values revealed consistent population-level differences, with higher values in Dune genotypes across habitats, indicating a constitutively elevated oxidative load relative to antioxidant protection and suggesting differentiation in redox regulation between populations. Overall, leaf trait variation in I. pumila appears to be primarily driven by plastic responses to light conditions, while differentiation in oxidative physiology contributes to functional divergence between populations. Full article

This study investigates the transient wheel–rail contact mechanics of welded joints in heavy-haul rails via a validated 3D finite element model, and analyzes the stick-slip behavior, dynamic response and elastoplastic characteristics in the base material zone, heat-affected zone and weld bead zone. Results show a distinct contact state transition from stick-slip in the base material to predominant slip within the welded zones, indicating higher wear susceptibility. Dynamic response analysis reveals the highest and lowest contact-point acceleration amplitudes in the base material and heat-affected zone, respectively, due to material heterogeneity. Plastic deformation consistently initiates at the rail surface, where stress and strain concentrate, establishing it as the primary site for damage nucleation. A systematic parametric study shows that plastic deformation can be effectively mitigated by increasing the yield strength and elastic modulus of the welded joint material, or reducing the wheelset velocity, unsprung mass and wheel–rail friction coefficient. In contrast, adjusting the primary suspension and fastener parameters exerts a negligible influence on plastic deformation control. These findings provide a mechanistic basis for optimizing the performance and maintenance of welded joints in heavy-haul rail operations. This study reveals the coupling law of multiple mechanisms among contact behavior, dynamic response and material failure during the damage initiation process of rail welded joints from the mechanistic perspective, which provides a theoretical basis for the structural optimization, condition assessment and maintenance of rail welded joints in heavy-haul railways. Full article

Root plasticity is vital for crop survival amid global warming. Yet, the molecular mechanisms governing wheat root thermotolerance remain largely unknown. In this study, we combined phenomics, transcriptomics, and metabolomics with machine learning to analyze the performance of heat-tolerant cultivar YM158 and heat-sensitive cultivar YM15 under varying heat stress. While high temperatures (35 °C) severely inhibited root growth and caused oxidative damage in YM15, YM158 maintained robust root architecture and redox balance. Using weighted gene co-expression network analysis (WGCNA) alongside the random forest feature selection algorithm, we identified the flavonoid biosynthesis pathway as central to thermotolerance. Protein–protein interaction network analysis revealed that wheat root adaptability to high temperatures involves maintaining protein homeostasis via the endoplasmic reticulum protein processing system, specifically activating the flavonoid biosynthesis pathway and enhancing the antioxidant enzyme system. Furthermore, we identified a potential regulatory hub involving the cell wall sensor FERONIA (FER) and heat shock factors (HSFs), highlighting a complex interaction between hormonal signaling and secondary metabolism. Our study offers a detailed map of root heat adaptation and positions the flavonoid-mediated antioxidant system as a promising target for breeding climate-resilient crops. Full article

The shear strength of reinforced concrete members without transverse reinforcement remains a critical design issue, particularly for thick and slender structural members where pronounced size effects may significantly reduce the nominal shear strength. This study investigates the combined influence of member depth, concrete compressive strength, and longitudinal reinforcement ratio on the shear capacity of beams without stirrups through nonlinear finite element analyses (NLFEA). Beam depths ranging from 1000 mm to 4000 mm and concrete strengths between 30 MPa and 50 MPa were considered, together with variations in different longitudinal reinforcement ratios. The numerical results confirmed a clear deterministic size effect, with nominal shear stresses decreasing systematically as the effective depth increased, while the influence of compressive strength was found to be secondary. The depth-dependent response was successfully represented using Bažant’s energetic Size Effect Law (SEL Type II), and the calibrated parameters provided an excellent fit to the numerical database. Furthermore, the numerical predictions of shear capacity were compared with major design provisions, including ACI 318 (2014 and 2019), Eurocode 2 (EN 1992-1-1:2005 and EN 1992-1-1:2023), and fib Model Code approaches with levels of approximation (LoA) 1 and 2. The results highlight that older formulations such as ACI 318-2014 and EN 1992-1-1:2005 tend to be unconservative for deep members, whereas EN 1992-1-1:2023 offers significantly improved agreement with reduced scatter. Among the evaluated expressions, fib Model Code LoA1 was the most conservative, while LoA2 provided the most accurate overall predictions. The findings emphasize the importance of incorporating size-effect considerations in modern shear design models, particularly for large reinforced concrete structures such as bridge decks, thick slabs, and dam walls. Full article

Precast reinforced concrete (RC) structures offer advantages in terms of construction efficiency and quality control; however, their seismic performance is governed by the behavior of the beam–column connections. This study presents an experimental investigation of the cyclic response of precast RC beam–column joints that include a composite steel connection, designed to enhance strength, stiffness, and damage control in critical regions. A composite joint specimen was tested under displacement-controlled cyclic loading, and its behavior was compared with that of a corresponding pure RC connection. Experimental results showed that the composite configuration effectively prevented premature failure at the beam–column interface, relocated plastic hinges away from the joint core, and significantly improved the load-carrying capacity, stiffness, and energy dissipation. To interpret the experimental observations and examine the internal stress transfer and evolution of damage, a three-dimensional nonlinear finite-element model was developed. The simulations reproduced the observed modes of failure, shapes of deformation, hysteretic responses, and moment distribution trends, particularly in the post-yield and strain-hardening ranges. Although the pinching effects observed experimentally were not fully captured numerically, the overall levels of agreement in the ultimate strength and plastic hinge locations were satisfactory. The combined results indicate that composite steel-reinforced precast beam–column joints represent a promising solution for improving seismic performance. Full article

This paper presents an experimental and numerical study on the effect of steel fiber distribution on the flexural behavior of self-compacting mortars (FRSCMs). Six FRSCM mixtures were modeled in ABAQUS as prismatic specimens (40 × 40 × 160 mm³) subjected to static three-point bending. The methodology involved two steps: (i) preparation of six mortar variants composed of three layers with different hooked steel fiber dosages (20, 30, and 40 kg/m³ for M20, M30, and M40) assembled in various configurations to study fiber distribution effects; (ii) numerical modeling of prismatic specimens in ABAQUS, using structured meshing with C3D8R hexahedral elements. Each layer was meshed separately with aligned nodes to ensure proper assembly. Our results highlight the strong influence of fiber distribution: despite identical fiber content (90 kg/m³ of hooked steel fibers), flexural strength varied across beam configurations. Layered casting led to an increase in flexural strength of up to 71.83% compared to the reference. The numerical predictions closely matched the experimental results, with relative errors ranging from 1% to 8.13% for most variants, demonstrating the reliability of the model. The larger discrepancies observed for specimens M324 and M342 are attributed to the limitation of the study to the elastic domain, as damage and plasticity effects were not included in the simulations. The distribution and orientation of fibers (particularly steel fibers) in a cementitious matrix, namely concrete or cement mortar, has been the subject of several studies aimed at determining the best mechanical performance of fiber-reinforced concrete. The proposed modeling approach of bending mechanical behavior allows us to predict the effects of fiber distribution in fluid mortars and reinforced self-compacting mortars, thereby reducing the need for extensive experimental testing. It also represents a significant improvement over existing approaches reported in the literature. Full article

Type 1 diabetes (T1D) constitutes a chronic metabolic disorder attributed to the autoimmune destruction of insulin-producing pancreatic β cells, which most frequently occurs in childhood. Long-term complications of T1D are expected to occur mainly in adult life, whereas cognitive dysfunction can also occur in children and adolescents with T1D. Most studies demonstrate mild cognitive impairment, especially in the domains of memory, attention and executive functions, all of which affect academic performance, which may also negatively influence adherence to appropriate glucose monitoring and insulin treatment in children and adolescents with T1D. As a result, mild cognitive dysfunction can be an obstacle to both optimal glycemic control during childhood and adolescence and academic achievements for young individuals with T1D. The major metabolic changes occurring around the onset of diabetes, such as severe hyperglycemia and diabetic ketoacidosis, may have a negative impact on brain plasticity during this vulnerable period of neurodevelopment, especially in children diagnosed at a younger age. The pathophysiological mechanisms involved are closely related to increased oxidative stress and the accumulation of advanced glycation end products in the brain, thus leading to neuron cell damage and apoptosis. On the other hand, hypoglycemic episodes and glucose fluctuations may also impair neuronal integrity. The aim of the current narrative review is therefore to present the existing literature data on the clinical aspects, risk factors and molecular mechanisms associated with cognitive dysfunction in children and adolescents with T1D. Full article

The reinforced concrete (RC) Diaojiao frame structure is a widely used building form in the Luding red bed area. A large area of damage occurred in the Luding earthquake in 2022. It is very important to carry out seismic fragility research for damage evaluation and post-earthquake emergency management. Based on the incremental dynamic analysis (IDA), this paper explores the dynamic response law of the structure: the structural damage is distributed in Floor 1 > Floor 2 > Floor 3, and the damage of the C1_1 component is the most serious. Through the quantitative analysis of the structural damage matrix, the probability of structural damage under frequent earthquakes of 7 degrees and 8 degrees can be ignored. The probability of severe damage (SD) of Floor 1, Floor 2, Floor 3 and the building under maximum considered earthquakes of 9 degrees is 58.25%, 53.03%, 2.71% and 36.79%, respectively. In this paper, PGA is used as an index to divide the damage state into four categories: elastic state, elastic-plastic state, plastic state and large deformation state. Based on the actual earthquake PGA, the structural damage can be determined quickly and accurately, which provides scientific support for the formulation of emergency measures. Full article

The migratory locust, Locusta migratoria, possesses a highly specialized olfactory system that exhibits remarkable density-dependent plasticity, which plays a crucial role in the formation of large aggregations and the resulting severe crop damage. However, the mechanisms by which population density influences phase-related plasticity in olfactory perception remain largely unexplored. Here, we conducted a comprehensive, multi-level comparison of the peripheral olfactory system between solitary and gregarious locusts. We found that solitary male locusts display the highest total number of antennal sensilla, with basiconica sensilla being the most abundant and particularly prominent in this group. At the physiological level, solitary males also displayed the greatest overall sensitivity in their electroantennogram (EAG) responses to volatile compounds highly specific to both phase and sex. At the molecular level, solitary males exhibited a significant upregulation of Or genes across all sex-phase combinations. These findings illuminate the intricate adaptation strategies of the insect peripheral olfactory system in response to environmental changes. Full article

Nuclear mechanics and mechanotransduction are involved in the migration and invasion process, such as those in which the cells need to deform themselves to pass through constrictions. Specifically, properties like nuclear softness, viscoelasticity, plasticity (like nuclear pore complexes) and deformability are critical in cancer and its malignant progression. The nucleus represents a physical barrier for the migration and invasion in dense 3D extracellular matrix (ECM) scaffolds. Therefore, the deformability of the nucleus seems to determine the migration limit in circumstances where the enzymatic remodeling of the surroundings is impaired. There are still significant knowledge gaps regarding effects of nuclear deformation during cancer dissemination. It seems that nuclear deformation can alter gene transcription, induce alternative splicing processes, impact nuclear envelope rupture, nuclear pore complex dilatation, damage the DNA, and increase the genomic instability. These mechanically induced alterations can in turn impact the migratory behavior of the cancer cells. The stiffness of the nucleus relies on the condensation of chromatin, and the nuclear lamina, which consists of a network of intermediate filaments underneath the nuclear envelope. All of this is discussed in the review and it is argued that nuclear deformability is universally found in various cancer types. Another focus is placed on the nuclear envelope proteins like emerin, and the SUN-KASH complex and how they contribute to the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex, which consequently couples the nucleus and the cytoskeleton. It is argued that this connection is crucial for force transmission, which governs nuclear stiffness dynamically, depending on the force applied. In this review, recent findings are described that couple ECM-induced nuclear mechanosensing and mechanotransduction with the migration and invasion of cancer cells. Moreover, it is suspected that changes in the mechanosensory characteristics of the cell nucleus could play a pivotal part in the malignancy of cancer cells and the heterogeneity of tumors. Finally, it is discussed what impact the individual elements of the nucleus offer to mechanically alter cellular migration and invasion in cancer and its malignant progression. Full article

Physics-based constitutive modelling remains a cornerstone for predicting ductile damage and fracture in metallic materials, particularly where microstructural mechanisms govern macroscopic response. Over the past two decades, a wide range of crystal plasticity, porous plasticity, and void-based fracture models have been proposed to capture deformation localisation, void growth, and coalescence under complex loading paths. However, these developments are often presented in isolation, obscuring their shared physical assumptions and limiting their transferability across material systems and length scales. This article provides a microstructure-sensitive perspective on the constitutive modelling of ductile damage and fracture, with particular emphasis on crystal plasticity-based frameworks, void growth and coalescence mechanisms, and interface-driven fracture. Rather than attempting an exhaustive review, this review highlights the unifying concepts, modelling trade-offs, and recurring challenges related to parameter identifiability, scale bridging, and predictive robustness. It further clarifies how physics-based constitutive descriptions can be systematically integrated into modern fatigue and fracture assessments and situates these developments relative to emerging data-assisted and machine-learning-enhanced modelling strategies. By reframing established constitutive models within a coherent physical narrative, this perspective aims to support more transparent model selection, improve interpretability, and guide future developments in the multiscale damage and fracture modelling of metallic materials. While these frameworks offer enhanced microstructure sensitivity, their parameter richness and experimental calibration demand currently limit widespread industrial deployment, motivating ongoing work on reduced-order and data-assisted variants. Full article

Beam-to-column connections govern both seismic performance and post-earthquake repairability of steel moment-resisting frames. Yet direct, apples-to-apples comparisons among welded, bolted, and repair-oriented replaceable-fuse moment connections are still scarce, which hinders rational selection for resilient construction. This study conducts a unified finite-element comparison of three representative joint archetypes—W-RBS, Bolted, and Prefab-web-fuse—under monotonic and cyclic loading. Consistent moment-rotation definitions are adopted, and normalized indices are introduced to compare hysteresis shape, degradation, and energy dissipation across joint concepts with different strength scales. Component-wise plastic dissipation is also extracted to quantify damage localization and assess main-frame protection and replaceability. Results reveal clear trade-offs: W-RBS provides the highest strength and dissipation but degrades most in stiffness; the bolted joint shows pinching due to interface compliance; and the web-fuse concept concentrates inelastic demand in a replaceable segment, supporting repairability-oriented design. The proposed framework offers mechanism-based guidance for selecting steel moment connections toward resilient and repairable frames. Full article

Neurodegenerative diseases share a mitochondrial–immune axis in which impaired oxidative phosphorylation reshapes neuronal metabolism and drives chronic inflammation. Complex I play a redox gatekeeper role at the coenzyme Q (CoQ) junction: catalytic defects, misassembly, or reverse electron transport over-reduce the CoQ pool, increase electron leak, and elevate ROS. How respiratory supercomplex plasticity (CI-CIII₂, CIII₂-CIV_n, or CI-CIII₂-CIV_n) modulates carrier channelling, flux control, and ROS propensity through dynamic reorganization of the electron transport chain is highlighted. Excess ROS damages lipids and mitochondrial DNA, promoting the release of mitochondrial damage-associated molecular patterns s that activate NLRP3 inflammasome signalling, cGAS-STING-dependent interferon programs, and endosomal TLR9 pathways, establishing feed-forward loops between mitochondrial injury and neuroinflammation. Disease-focused sections integrate evidence from Parkinson’s, Alzheimer’s, amyotrophic lateral sclerosis, and Huntington’s models, and map these mechanisms onto therapeutic opportunities spanning electron transport chain support, supercomplex stabilization, and consider mtDNA-sensing inflammatory nodes. Full article

The paper presents results of a degradation analysis of polyamide 12 reinforced with carbon fibers used for additive manufacturing of cycloidal gear. Both FEM simulation and a fatigue test indicated the ability of the material to withstand loads during the work of cycloidal transmission. However, a run-to-failure (RTF) test revealed critical failure after 10⁵ cycles, with displacement and damage of the material in the area close to bearing instead of expected areas of teeth being in friction with pins. Acceleration analysis with time synchronous averaging (TSA) confirmed rapid degradation of the material’s strength at the end of the RTF test. It was found that the PA12 cycloidal gear damage was a result of fatigue accelerated by the temperature increase under the cyclic loads that took place during the RTF test. In particular, displacement of 0.2 mm did not appear in the specimens tested at 27 °C even after 10⁵ cycles, while at 140 °C this value was reached almost immediately. At 70 °C and 90 °C, plastic deformation of 0.2 mm was reached after 30,000 and 5000 cycles, respectively. The finding can be used in a predictive maintenance system of such cycloidal transmission with 3D-printed polymer gears. Full article