Search Results (884)

Road construction contributes to embodied carbon in infrastructure, with asphalt-bound layers often dominating construction-stage greenhouse gas emissions in flexible pavements. Reclaimed asphalt pavement (RAP) and high-modulus asphalt concrete can reduce virgin material demand and improve structural efficiency, but their sustainability benefit depends on maintaining equivalent pavement performance. This study develops a climate-informed, mechanistic, environmental, and economic Pareto optimization framework for RAP-modified high-performance asphalt concrete (RAP-HPAC) pavement sections in Alberta. The framework couples fitted dynamic modulus master curves, monthly pavement temperature inputs, ALVA layered elastic analysis, Asphalt Institute fatigue and rutting criteria, A1–A5 global warming potential (GWP), and Alberta 2026 installed unit-price cost data. The RAP-HPAC mixture contains 50% RAP and was designed through a balanced mix design to target approximately 80% effective RAP binder activation. Three traffic classes were evaluated: 731, 1300, and 5426 ESAL/day/direction, each with 2% annual compound growth over a 20-year design period. Relative to independently optimized conventional HMA controls, Pareto-selected RAP-HPAC sections reduced P50 construction-stage GWP by approximately 19–30% and first cost by approximately 6–11% at a conservative 0.90× RAP-HPAC cost multiplier. The results show that RAP-HPAC is most beneficial when used as a structural-bound base that replaces conventional asphalt-bound capacity while preserving sufficient granular support. The framework provides a reproducible design-stage approach for comparing recycled high-modulus asphalt mixtures using performance, carbon, and cost criteria simultaneously. Full article

Background: Football is an intermittent sport characterized by high physical and physiological demands, which may be influenced by the competitive level. Understanding differences in match load is fundamental for optimizing training planning, fatigue management, and athlete performance and injury prevention. This study aimed to evaluate and compare external and internal load in senior football players in Portugal across five distinct competitive levels. Methods: Wimu Pro^TM (Hudl, Lincoln, NE, USA) and Garmin Heart Rate bands (Garmin International Inc., Olathe, KS, USA) were used to quantify and evaluate the external and internal load of the players. A total of 96 athletes were assessed, with ages ranging from 19 to 36 years (mean: 24.28 ± 4.72), who were divided into five competition levels (1st Division (n = 19), 2nd Division (n = 21), 3rd Division (n = 14), 4th Division (n = 20), and Regional Division (n = 22). Results: Significant differences were observed between competitive levels across several external load variables (p > 0.001). The 3rd Division and 4th Division showed higher values in variables associated with reactive and high-intensity actions (p < 0.001; effect size: 0.287), whereas the 2nd Division exhibited a more controlled load profile. Regarding internal load, significant differences were only observed in average heart rate during the second half (p = 0.043; effect size: 0.085), indicating distinct capacities to maintain physiological intensity under fatigue. Conclusions: It can be concluded that competitive level influences load profiles in football, although the differences do not follow a linear pattern. External and internal loads demonstrate greater discriminatory capacity between competitive levels than internal load. Full article

Carbon-fiber reinforced polymer (CFRP) tendons have attracted increasing attention as corrosion-resistant prestressing elements for prestressed concrete and cable-supported structures; however, their practical implementation requires reliable verification of long-term mechanical performance and anchorage reliability. In this study, a 9.5 mm pultruded CFRP tendon and compression-type anchorage system were developed and experimentally evaluated through relaxation, creep rupture, and fatigue tests. The tendon exhibited a tensile strength of 2501 MPa and an elastic modulus of 132.5 GPa. Relaxation tests were conducted at an initial load corresponding to 70% of the ultimate tensile capacity, and the measured relaxation loss after 1000 h was 1.02%. Based on logarithmic regression of the measured data, the relaxation loss at 1,000,000 h was estimated to be 2.11%; however, this value should be interpreted as an extrapolated long-term estimate rather than a directly verified result. Creep rupture tests performed at load ratios of 82.4–100.0% yielded an estimated 1,000,000 h creep rupture load ratio of approximately 80%, although the prediction is subject to uncertainty because of the limited number of specimens and scatter in rupture times. Fatigue tests indicated that the CFRP tendon–anchorage assembly maintained stable performance up to 2,000,000 cycles without measurable degradation in elastic stiffness under the adopted loading conditions. These results suggest that the developed CFRP tendon–anchorage system has promising potential for prestressing applications, while further long-term tests with a larger number of specimens are required to improve the statistical reliability of the extrapolated relaxation and creep rupture predictions. Full article

Exercise-induced fatigue is a common phenomenon after intense exercise or labor, which significantly affects an individual’s exercise performance and physical and mental health. Its timely recovery is crucial for enhancing exercise capacity and preventing injuries. Acupuncture, as a “simple, convenient, inexpensive, and effective” non-pharmaceutical therapy in traditional Chinese medicine, has shown potential unique advantages in the prevention and treatment of exercise-induced fatigue. This narrative review summarizes the recent research progress, with core mechanisms including the inhibition of oxidative stress and inflammation, regulation of energy metabolism, and improvement of central nervous system function, which are mainly verified by preclinical animal studies and partially supported by small-sample clinical trials. The application effects are reflected in the fact that pre-acupuncture before fatigue can enhance anti-fatigue reserves, and post-fatigue treatment can alleviate symptoms and promote recovery, with human evidence limited to small-scale clinical observations. In conclusion, acupuncture has potential therapeutic effects on the prevention and treatment of exercise-induced fatigue, providing a theoretical and practical reference for clinical application. Full article

The horse represents one of the most physiologically specialized athletic mammals, capable of sustaining both high-intensity and prolonged exercise. Central to this remarkable performance capacity is the metabolic adaptability of skeletal muscle and its mitochondrial network. This narrative review synthesizes current evidence from equine, human, and rodent studies on exercise-induced mitochondrial remodeling in equine skeletal muscle. A comprehensive literature search was conducted across PubMed, Web of Science, and Scopus using terms related to equine exercise physiology, mitochondrial biology, and skeletal muscle metabolism. Preference was given to peer-reviewed original research and review articles. Mitochondria regulate oxidative phosphorylation, substrate oxidation, redox signaling, and cellular responses to metabolic stress induced by exercise. Training induces extensive mitochondrial adaptations, including mitochondrial biogenesis, remodeling of the respiratory chain, enhanced oxidative phosphorylation efficiency, and increased metabolic flexibility. These adaptations are believed to contribute to improvements in aerobic capacity, delayed fatigue onset, and enhanced recovery following exercise, although direct mechanistic evidence in horses remains limited. In equine skeletal muscle, mitochondrial plasticity is closely linked to muscle fiber composition and the distribution of oxidative and glycolytic fibers. Exercise-induced signaling pathways involving AMP-activated protein kinase (AMPK), Ca²⁺-dependent kinases, and the transcriptional coactivator PGC-1α regulate mitochondrial biogenesis and metabolic remodeling. In addition, mitochondrial dynamics, including fusion, fission, and mitophagy, maintain mitochondrial quality and functional efficiency during repeated training stimuli. Experimental studies in Thoroughbred and Standardbred horses demonstrate that training has been associated with increases in mitochondrial density and respiratory capacity in equine skeletal muscle, contributing directly to improved aerobic performance and metabolic efficiency. However, mitochondrial adaptations must be interpreted within the broader context of musculoskeletal adaptation, as metabolic improvements may occur faster than structural adaptation of tendons and ligaments. This review synthesizes current knowledge on exercise-induced mitochondrial remodeling in equine skeletal muscle, while highlighting the limited mechanistic evidence available in horses and the need for more standardized longitudinal studies. Full article

Polyester (PET) fibers are widely used to reinforce asphalt materials; however, their smooth and hydrophobic surfaces limit interfacial bonding and restrict their reinforcing efficiency. This study develops an eco-friendly surface modification method based on the chemical modification of gallic acid (GA) and aminosilane (KH792) to enhance the compatibility between PET fibers and asphalt. Modified fibers with various molar ratios of GA/KH792 were prepared and incorporated into asphalt mastic. Their performance was evaluated using softening point, cone penetration, dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), and bending beam rheometer (BBR) tests, combined with interfacial interaction analysis and scanning electron microscopy (SEM). The results show that surface modification significantly improves the reinforcing effect of PET fibers. In particular, the co-modified fiber with a GA/KH792 ratio of 1:1 exhibits the best performance, with increases of 27% in softening point and 105% in shear strength, as well as notable improvements in rutting resistance, fatigue performance, and temperature stability. Interfacial indices and SEM observations confirm enhanced adhesion, dispersion, and load transfer capacity. However, the improvement in low-temperature performance is limited. Overall, GA/KH792 chemical modification effectively enhances fiber asphalt interfacial interaction and provides a simple and sustainable approach for developing high-performance asphalt materials. Full article

Rock–concrete composites are critical load-bearing elements in geotechnical engineering applications such as slope support. Their mechanical response and damage evolution after fatigue disturbances, such as blasting and mechanical operations, govern the long-term stability and safety of engineered structures. To fully capture these complex behaviors, this study presents a novel multi-scale approach by integrating uniaxial compression tests with three-dimensional digital image correlation and discrete element modeling. This combined experimental–numerical framework is employed to systematically examine the macro- and meso-scale mechanical behavior, crack evolution, and energy response of composites with varying interface angles after quasi-static cyclic loading. The results reveal that as the interface angle increases, the peak strength declines markedly while the brittleness index increases, reflecting a distinct transition in the failure mode from plastic-dissipation-dominated to elastic-energy-storage-dominated. Consequently, the dominant failure mechanism shifts from tensile to shear-slip control. Furthermore, fatigue disturbances exacerbate material degradation, inducing a composite “interface shear–end tension” failure in specimens with higher interface angles and significantly raising the proportion of shear cracks. Energy analysis indicates that cyclic loading enhances the elastic energy storage capacity, and the energy conversion threshold rises continuously with the interface angle. These findings clarify the multi-scale control mechanisms of interface geometry on fatigue-induced failure, providing a theoretical foundation for predicting fatigue life and enabling early pre-warning of failures in rock–concrete engineering structures. Full article

To investigate the rheological properties and compositional changes in SBS-modified bitumen under different aging conditions in the unique environmental conditions of the Xinjiang region, this study selected a local 70# base bitumen from Xinjiang and prepared modified bitumen by adding 4.0%, 4.5%, and 5.0% SBS modifier, respectively. RTFOT and PAV were used to simulate the short-term thermal-oxidative aging and long-term oxidative pressure aging processes of the bitumen samples, respectively. The three key indicators and dynamic rheological properties of the bitumen were tested for the original sample, as well as before and after short-term thermal-oxidative aging and long-term oxidative pressure aging. Thin-layer chromatography/flame ionization detection (TLC/FID) was used to analyze the migration patterns of the samples’ chemical components, and a random forest model was employed to establish a quantitative mapping between the four components of the modified bitumen and the rutting factor over a wide temperature range. The results indicate that aging weakens the improvement effect of SBS on the high-temperature performance of bitumen. However, 4.5% SBS-modified bitumen subjected to long-term oxidative pressure aging still maintains the best high- and low-temperature performance, elastic recovery capacity, and fatigue resistance compared to other dosage levels. It also has the highest bitumen content, which verifies the high-temperature performance of this dosage at the component level. Therefore, the optimal SBS dosage is recommended to be 4.5%. Notably, as the SBS content increases, it significantly regulates the increase in heavy fraction content during the aging process, while the decrease in light fraction content is not significantly affected by the content. Based on the random forest algorithm, a mapping relationship between fractions and properties under fully aged conditions was established. This study provides a theoretical basis for research on the modification and aging mechanisms of Xinjiang bitumen. Full article

Visual fatigue is a serious issue among Chinese secondary school students owing to prolonged daily exposure (8–10 h) to visual display terminals (VDTs) in widely equipped multimedia classrooms. To mitigate such effects, this exploratory study identifies promising lighting parameters by evaluating the influence of blackboard reflection coefficients, the ratio of desktop illumination to blackboard illumination, and correlated color temperature (CCT) in a simulated multimedia classroom environment. Thirteen participants performed visual tasks (Landolt ring visual acuity tests and Anfimov’s Chart Task) under various conditions. Visual fatigue scale (VFS-10), index of mental capacity (IMC), and eye movement parameters (EMP) were used to assess visual fatigue and efficiency. Results suggest that higher blackboard reflection coefficients improved efficiency and reduced fatigue. Increased blackboard illumination alleviated fatigue at constant CCT, whereas changes in desktop illumination showed no significant effect. The highest efficiency among the tested CCT values was observed at 4700 K, while visual fatigue was minimized at 4000 K. The findings provide preliminary practical applications for minimizing visual fatigue and improving performance efficiency in secondary school multimedia classroom environments equipped with VDTs. Full article

Background/Objectives: To evaluate the associations and concurrent validity between baseline functional and morphofunctional assessments in patients with cardiovascular disease participating in a Phase II cardiac rehabilitation program, as a basis for informing individualized exercise prescription. Methods: We conducted an observational retrospective cross-sectional study of patients enrolled in a Phase II outpatient cardiac rehabilitation program (January 2021–December 2023, Málaga). Functional assessments included handgrip strength (HGS), isometric biceps and quadriceps dynamometry, and direct assessment of 20-repetition maximum (20RM) through dynamic resistance exercises using external loads (defined as the maximum load allowing approximately 20 repetitions to near muscular fatigue). Aerobic capacity was evaluated using the 6-min walk test (6 MWT) and a modified Bruce exercise stress test with estimated METs. Morphofunctional assessment included vector bioimpedance analysis (phase angle [PhA], fat-free mass [FFM], body cell mass [BCM]) and rectus femoris ultrasound (cross-sectional area [RF-CSA] and contracted diameter [RF-CON]). Correlation and linear regression analyses were performed. Results: The sample included 223 participants (78.0% male; age 57.7 ± 8.6 years). HGSmax correlated strongly with 20RM biceps (r = 0.89) and moderately with quadriceps (r = 0.72). 6 MWT distance and speed correlated with ergometry-derived METs (r = 0.38–0.40; p < 0.001), whereas Borg ratings correlated inversely with METs and exercise time (r = −0.32 to −0.34; p < 0.001). PhA, BCM, FFM, and rectus femoris ultrasound measures correlated with both strength and aerobic outcomes (ρ ≈ 0.33–0.50; all p < 0.001). In regression analyses, HGSmax was the main predictor of 20RM biceps (R² = 0.792) and showed moderate predictive capacity for quadriceps performance (R² = 0.521). The MET model demonstrated limited explanatory capacity (R² = 0.288). Conclusions: The integration of simple, accessible, and reproducible tools such as HGS and the 6 MWT with morphofunctional parameters may provide a pragmatic approach to support individualized exercise prescription in cardiac rehabilitation. While stronger associations were observed for upper-limb resistance performance, the predictive capacity for lower-limb strength and aerobic exercise intensity was more moderate and should be interpreted cautiously. These findings support the potential clinical utility of combining functional and morphofunctional assessments in routine cardiac rehabilitation practice. Full article

To address the durability limitations of conventional crack sealants under coupled extreme temperatures and traffic loads in long-life pavements, a bio-oil composite-modified patching material was developed using 90# base asphalt as the matrix, synergistically modified with crumb rubber (CR) and epoxidized soybean oil (ESO). To resolve the contradictory requirements for high elasticity and thermal expansion/contraction coordination in sealants, ESO was introduced; its polar epoxy groups optimize phase compatibility and promote low-temperature stress relaxation without restricting thermal deformability. Rheological evaluations revealed that the optimal system (OPT) successfully extended the service temperature window from PG 76–−24 °C (baseline) to PG 82–−24 °C, significantly enhancing its adaptability to extreme climatic fluctuations. At −24 °C, OPT exhibited a reduced creep stiffness (S) of 164 MPa and an increased creep rate (m) of 0.312, with a cracking resistance ratio (k) as low as 525.6; the quantitative significance of these metrics lies in granting the sealant superior stress relaxation capacity, enabling it to accommodate dynamic crack widening without interfacial debonding or brittle fracture. Fatigue testing via time sweeps demonstrated that N_f50 reached 2890 cycles, highlighting robust long-term resistance against high-frequency shear strains induced by tire edges. Micro-mechanistic analyses (FTIR, TG/DTG, and DSC) confirmed that the modification is primarily driven by physical blending. The elevation of the thermal decomposition threshold (T5%) to 302.4 °C and the residue at 600 °C to 44.8% provide a critical safety margin for high-temperature construction heating, preventing thermal degradation. Furthermore, the glass transition temperature (T_g) decreased to approximately −35.2 °C. These findings establish a rigorous quantitative and mechanistic framework for designing sustainable, high-performance patching materials for resilient pavement maintenance. Full article

Skeletal muscle plasticity is modulated by a delicate equilibrium between reactive oxygen species (ROS)-mediated signaling and oxidative distress. Although excessive oxidant accumulation impairs excitation–contraction coupling, accelerates fatigue, and contributes to muscle dysfunction, transient and compartmentalized ROS signals are now recognized as important modulators of mitochondrial biogenesis, metabolic remodeling, proteostasis, and tissue repair processes after contractile stress. This review synthesizes the biphasic nature of redox biology in exercise physiology, interpreting this duality through the paradigm of hormesis. We discuss modality-specific redox responses associated with endurance, resistance and high-intensity interval training, emphasizing that adaptive outcomes depend not on global redox shifts, but on spatiotemporally confined signaling cascades within specific nanodomains. Furthermore, we evaluate the controversial role of antioxidant supplementation, highlighting evidence that high-dose or poorly timed antioxidant intake attenuates specific exercise-induced adaptive responses. We further discuss how aging and chronic disease narrow the adaptive redox window by impairing mitochondrial quality control, inflammatory resolution, and recovery capacity. This paradigm supports a precision exercise strategy in which training modality, intensity, recovery, and nutritional interventions are aligned to preserve adaptive redox signaling while avoiding cumulative oxidative injury. Full article

Combining surface texturing and solid lubricant coating is an effective approach to improve tribological performance and service life in surface engineering. However, few studies have systematically compared texture types and their adaptability to varying working conditions. In this work, a textured composite coating with a three-level gradient structure (interface texture–coating–surface texture) was prepared via plasma spraying and laser texturing. Reciprocating dry friction tests were carried out to compare the tribological properties of dimple, linear, and sinusoidal textures. The effects of normal load and sliding speed on friction and wear behavior were investigated. Results demonstrate that the average friction coefficients follow the order: non-textured coating > dimple-textured coating > linear-textured coating > sinusoidal-textured coating. The sinusoidal texture provides the lowest friction coefficient and superior debris capture and storage capacity, which effectively mitigate abrasive wear, adhesive wear, and fatigue spalling, leading to optimal friction reduction. Increasing the load moderately reduces the friction coefficient, but the coating fails rapidly due to severe plastic flow and adhesive tearing when the load exceeds 100 N. The textured composite coating presents favorable velocity adaptability with a friction coefficient reduced by 23.8%–41.3% relative to the non-textured coating. Yet the texture fails rapidly when the sliding speed exceeds 100 mm/s because of intensified adhesive wear and plastic deformation. Full article

In this study, fatigue crack propagation due to unexpected damage caused by fretting in an aero engine high-pressure turbine (HPT) blade slot is analyzed. Two different numerical crack models were applied and studied to simulate fatigue crack propagation caused by amplitude service loading. Also, the goal was to demonstrate the capacities of numerical simulations, including their limitations, especially when the crack propagation behavior should be predicted for critical parts of the real structure. It is shown that the structural integrity of the analyzed component is not jeopardized by the existing damage. Full article

Heart failure (HF) is a heterogeneous clinical syndrome with increasing prevalence among adults worldwide. It is characterized by complex central and peripheral alterations that contribute to exercise intolerance, fatigue, dyspnea, and reduced quality of life. Inspiratory muscle weakness (IMW) plays a key role in this vicious cycle by exacerbating symptoms and further limiting functional capacity. Inspiratory muscle training (IMT) has emerged as a potential adjuvant in comprehensive HF management and is a physiologically grounded and promising tool in the contemporary HF therapeutic toolkit. Its integration into multimodal rehabilitation programs may mitigate the cycle of dyspnea and deconditioning in patients with HF. On this basis, we provide an overview of the pathophysiological mechanisms underlying IMW and present the practical characteristics of IMT programs, synthesizing current evidence regarding its clinical efficacy and implementation challenges. Full article