Search Results (1,200)

We investigated the effect of film thickness d on the acoustic response of titanium dioxide (TiO₂) layers deposited on Ti, SiO₂, Al₂O₃, and Si substrates. For each TiO₂ thickness–substrate pair, we computed reflection coefficients and acoustic signatures under normal operating conditions of a conventional scanning acoustic microscope, then deduced the Rayleigh-wave velocity V_R from spectral analysis of the oscillatory layer–substrate signatures. As d increased, V_R either rose or fell, depending on the layer/substrate pair, and eventually approached a saturation value. For TiO₂/SiO₂ and TiO₂/Ti, V_R increased from those of the bare substrates (SiO₂: 3415 m/s; Ti: 2965 m/s) toward 3830 m·s⁻¹, the bulk TiO₂ value. For TiO₂/Al₂O₃ and TiO₂/Si, V_R decreased from the substrate values (Al₂O₃: 5700 m/s; Si: 4712 m/s) toward the same TiO₂ saturation. These dispersion trends are consistent with stiffening (V_R (TiO₂) > V_R (Substrate)) or loading (V_R (TiO₂) < V_R (Substrate)) effects. The resulting V_R–d dispersion charts provide theoretical reference trends relating thickness and Rayleigh-wave velocity for the idealized TiO₂/substrate systems considered here. Full article

This study investigates the combined effects of thermal and moisture aging on PVC-insulated low voltage (LV) photovoltaic (PV) cables using an accelerated-aging design to represent realistic PV operating conditions commonly encountered in hot and humid climates. Thermal aging was carried out at 90 °C for five aging cycles, with each thermal cycle followed by controlled moisture injection to simulate moisture stress. The degradation behavior was evaluated using broadband dielectric spectroscopy, FTIR analysis, and Shore D hardness measurements. Changes in dielectric dissipation factor (tanδ) and real permittivity (${\epsilon }^{\prime }$) were analyzed over a wide frequency range, with 100 kHz selected for its high sensitivity to aging-induced oxidation-related dipolar and interfacial polarization mechanisms. Degradation indices (DI) and degradation rates (DR) were derived from tanδ and correlated with mechanical and chemical changes. The results showed a 5% and 7% increase in tanδ at 100 kHz and in hardness, respectively, with decreases of 68% and 75% in the carbonyl and hydroxyl indices, respectively. Three distinct aging stages were identified: early thermo-oxidation with limited functional impact; mid-stage dehydrochlorination and moisture interaction; and late-stage chain scission, plasticizer loss, and insulation stiffening. The findings demonstrate the importance of climate-specific aging assessment and confirm the effectiveness of integrated electrical, mechanical, and chemical diagnostics for PV cable condition monitoring. Full article

Background/Objectives: Presbyopia is an age-related decline in near vision associated with lens stiffening and neuroretinal changes, while evidence for the effects of berry-derived phytochemicals remains limited. We investigated whether AKB, a double-standardised berry extract (anthocyanins ≥ 25%, iridoids ≥ 4.5%) from Aronia melanocarpa, Lonicera caerulea, and Vaccinium myrtillus, influences visual performance and circulating biomarkers potentially relevant to ocular homeostasis. Methods: In a randomised, double-blind, placebo-controlled, two-period crossover trial, 23 adults aged >50 years received AKB (400 mg twice daily) or placebo for 6 weeks, separated by a 5-week washout. Results: Compared with placebo, AKB was associated with improvements in selected visual-function outcomes, including near contrast sensitivity and visual-field parameters, together with directionally favourable changes in VEP and OCT readouts. AKB supplementation was also associated with lower circulating αA-/αB-crystallin and ALDH1A1 levels and higher circulating TRPV4 levels, whereas systemic antioxidant enzymes and advanced glycation end-products remained unchanged. Given the small sample size and the indirect nature of the biomarker assessment, these findings should be considered preliminary. Conclusions: Overall, short-term AKB supplementation was associated with modest, exploratory changes in selected functional and systemic biomarker outcomes, but larger and longer-term studies are needed to confirm clinical relevance and clarify underlying mechanisms. Full article

The relationship between lifestyle, ocular biomechanical behavior, and myopia is not well established in the literature. The present study aims to describe changes in ocular biomechanics during adolescence and to explore their relationship with lifestyle factors and myopic progression. Prospective cohort study including 63 adolescents (126 eyes) with a mean age of 14.1 ± 2.6 years old examined twice over a 30 ± 0.9-month period. The data from biomechanics, biometry, corneal tomography, and lifestyle was addressed. The relationships between biomechanical changes, biometric and refractive variation, and lifestyle variables were analyzed using parametric and non-parametric statistics with a significance level of p < 0.05. A biomechanical stiffening trend was found. Axial elongation was 0.12 ± 0.17 mm, and refractive shift was −0.32 ± 0.87 D. The history of allergies was associated with greater axial growth (p = 0.032) and smaller increase in stress–strain-index (SSI) (p = 0.01). Myopization was higher in eyes with ocular surface symptoms (p = 0.049) and those with reported eye-rubbing habits (p = 0.04), with a lower gain in stiffness (p < 0.05). Outdoor activities were associated with higher gain in corneo-scleral stiffness (p < 0.05). Reduced myopization correlated directly with the increase in the SSI (p < 0.05) and inversely with the Integrated Radius (p < 0.05). Greater increases in axial length (AL), vitreous cavity length (VCL), and the ratio between VCL and AL (R_VCL/AL) correlated negatively with the increase in the SSI (p < 0.05). The increase in the R_VCL/AL correlated positively with the time spent on digital devices and negatively with the amount of outdoor activity (p < 0.05). Biomechanics may represent the physiological bridge between the environmental exposure and myopization, as lower gain in corneo-scleral stiffness was consistently associated with greater axial elongation and refractive myopization, with outdoor activity appearing to be protective. Full article

This study analyzes the effect of two bioactive additives—caffeic acid and natamycin (Natamax^®)—on the properties of poly(butylene succinate) (PBS) in the context of applications in biodegradable active packaging. Materials containing 1, 3, and 5 wt.% of the additives were prepared by melt blending and characterized in terms of density, rheological behavior (MFR), mechanical properties, thermal stability (TGA), and thermal behavior and crystallization (DSC). Caffeic acid strongly reduced the melt viscosity (reflected by a significant increase in MFR) and, at higher concentrations, led to material stiffening and increased strength at the expense of a pronounced reduction in deformability. Natamycin exhibited a milder rheological effect; at 1 wt.% it simultaneously improved strength and elastic modulus, whereas at higher loadings it deteriorated mechanical performance due to structural effects. Both additives were thermally compatible with PBS; caffeic acid introduced an additional degradation step, while Natamax^® did not significantly alter the degradation mechanism. The results indicate that both the type and concentration of the additive govern the structure–property–function relationships and enable the design of PBS-based packaging materials with controlled performance and functional characteristics. Full article

Background: Early vascular aging (EVA) reflects accelerated arterial stiffening and is closely linked to cardiovascular and renal target organ damage. The Early Vascular Aging Ambulatory score (EVAAs) estimates EVA using ambulatory blood pressure monitoring (ABPM) and routinely available clinical parameters. We aim to investigate the association between EVAAs-defined early vascular aging and markers of kidney involvement—particularly albumin-to-creatinine ratio (ACR)—in a hypertensive population. Methods: Fifty treated hypertensive adults undergoing 24 h ABPM were enrolled. All participants underwent laboratory evaluation, including serum electrolytes and 24 h urine collection for albumin, creatinine, sodium, and potassium. EVAAs was calculated using ABPM-derived parameters and established cardiovascular risk factors. Results: EVAAs was positively correlated with ACR (r = 0.276, p = 0.049). In addition, inverse correlations were observed between EVAAs and serum potassium (r = −0.290, p = 0.038) and serum sodium (r = −0.284, p = 0.046). Participants with moderately increased albuminuria tended to exhibit higher EVAAs values, although this difference did not reach statistical significance. Conclusions: EVAAs is associated with early markers of renal involvement in hypertensive patients, supporting its potential role as a non-invasive indicator of subclinical target organ damage. Larger studies are warranted to confirm these findings and to further validate EVAAs as a clinically useful marker of EVA. Full article

Cervical Intervertebral Disc Degeneration (CIVDD) involves significant microenvironmental physical stiffening, forcing nucleus pulposus cells (NPCs) into a rigid phenotype via F-actin over-assembly. It remains unclear if cyclic tensile strain (CTS) can reverse this physical stiffening, particularly in severe degeneration. This study stratified 18 patients into Mild, Moderate, and Severe cohorts based on MRI. Primary NPCs were subjected to physiological 5% CTS (1 Hz, 24 h). Atomic Force Microscopy (AFM) and immunofluorescence were utilized to evaluate Young’s modulus and cytoskeletal remodeling. Results demonstrated that baseline cellular stiffness increased significantly with degeneration severity. Following CTS, all groups exhibited universal de-stiffening and F-actin depolymerization. Crucially, a “Degeneration Paradox” emerged: the Severe group displayed the highest relative elastic modulus recovery rate, significantly surpassing the Mild group. This microscopic recovery correlated inversely with preoperative disc height loss and range of motion. We conclude that severely degenerated cells are not metabolically quiescent but “physically locked” by a rigid cytoskeleton. Physiological CTS restores compliance via mechanical unloading, confirming that severe cells retain superior relative mechanoplasticity and may benefit from mechanotherapy-based “unlocking” strategies. Full article

Microbial polysaccharides are attracting increasing interest as water-processable polymers for extrusion-based additive manufacturing due to their ability to form physically stabilized networks without covalent cross-linking. In this study, a kefiran–propylene glycol (PG) formulation was developed to investigate whether time-dependent supramolecular reorganization can be exploited to control print fidelity. Extrusion performance was assessed through quantitative filament collapse analysis, while rheological behavior was characterized by oscillatory strain, frequency, and time sweep measurements. Filaments printed 5 min after PG addition showed pronounced sagging (δ/(L/2) ≈ 0.35 at the largest spans), whereas after 15 min the normalized deflection decreased below 0.03, indicating a marked improvement in self-supporting capability. Time sweep experiments revealed a continuous increase in storage modulus from ~100 to ~1200 Pa over 1800 s, consistent with progressive viscoelastic stiffening. Freeze-dried constructs exhibited an interconnected porous architecture with a predominant pore population between 6 and 20 µm and an apparent porosity of 60.9 ± 1.2%. Upon rehydration at 37 °C, samples swelled to ~350% within 5 h and showed gradual mass loss over 56 days while remaining intact. ATR–FTIR confirmed the preservation of the polysaccharide backbone without evidence of new covalent functionalities. Extrusion fidelity is therefore governed by progressive supramolecular consolidation within a physically assembled network, rather than by any form of chemical cross-linking. Full article

Vascular ageing is a complex process marked by progressive endothelial dysfunction, chronic low-grade inflammation (“inflammageing”), and reduced regenerative capacity, driven in part by an imbalance between protective endothelial autophagy and cellular senescence characterized by a proinflammatory senescence-associated secretory phenotype (SASP). Disruption of this autophagy–senescence axis accelerates vascular inflammation, arterial stiffening, and atherogenesis. High-intensity interval training (HIIT), consisting of repeated bouts of near-maximal anaerobic effort with recovery periods, is widely used by both elite and recreational athletes and is increasingly recognized as an effective nonpharmacological strategy to enhance endothelial function, arterial elasticity, and mitochondrial biogenesis. However, excessively intense or poorly structured HIIT, particularly in the absence of adequate recovery or in individuals with underlying cardiometabolic or vascular vulnerability, may induce endothelial stress and promote maladaptive vascular remodelling, including calcification and plaque instability. These considerations underscore the need for refined individualized exercise prescription strategies that balance performance benefits with endothelial protection. Based on these observations, here, we introduce a novel conceptual framework, “shear dose–calibrated HIIT,” designed to understand and define an optimal shear dose capable of maximizing autophagic flux while minimizing SASP activation. Experimental and clinical evidence of HIIT-induced effects on flow-mediated dilation (FMD), pulse wave velocity (PWV), and redox biomarkers is presented, followed by the proposal of a biomarker panel for assessing autophagic flux and cellular senescence in peripheral samples (peripheral blood mononuclear cells (PBMCs), extracellular vehicles (EVs), and plasma). This integrative approach, which combines vascular mechanotransduction, redox biology, and autophagic signalling, provides a novel translational perspective on how individually calibrated HIIT can promote vascular longevity and reduce cardiometabolic risk associated with aging and metabolic syndrome. Full article

Cancer is a heterogeneous systemic disease that is strongly influenced by dynamic interactions with the tumour microenvironment (TME). Despite major advances in understanding spatial and molecular tumour heterogeneity, the temporal dynamics of tumours have received far less attention. Growing evidence has linked circadian clocks to cancer risk, progression, and treatment response, including in breast cancer. However, temporal regulation has yet to be recognized as a cancer hallmark, and its interaction with the TME remains poorly understood. This review examines how circadian rhythms organize breast cancer biology through bidirectional interactions with the TME. Circadian clocks coordinate proliferation, DNA damage responses, metabolism, and immune surveillance. Ageing, chronic stress, and obesity, all of which are established breast cancer risk modifiers, disrupt these rhythms and are reciprocally exacerbated by circadian dysfunction, establishing feed-forward loops that accelerate disease. Within the TME, the extracellular matrix (ECM) plays a central role in mediating this bidirectional control. Stiffened fibrotic stroma dampens epithelial clock amplitude, while circadian rhythms in turn shape collagen turnover and ECM remodelling. These dynamics can foster inflammation, stem cell expansion, and metastatic dissemination, including time-of-day-dependent release of circulating breast tumour cells. Systemically, circadian clocks gate immune cell trafficking, creating predictable windows of immunosurveillance and therapeutic vulnerability. By integrating insights from mechanobiology, metabolism, immune regulation, and ageing, we position circadian timing as a unifying layer that connects cell-intrinsic programmes with the evolving breast TME. Understanding these connections opens new opportunities for chronotherapeutic strategies in which treatment timing is aligned with circadian rhythms to improve outcomes. Full article

The long-term behavior of reinforced concrete (RC) structures under sustained loading is strongly affected by creep and cracking, particularly under service conditions where tension stiffening and curvature changes are significant. This study investigates the flexural response of cracked RC beams through combined numerical and experimental analyses. A new 1D finite element model is proposed, integrating nonlinear material behavior, damage mechanics, and time-dependent effects, including creep in both compression and tension. The model relies on a layered fiber section approach and uses a Newton–Raphson iterative procedure to solve equilibrium, allowing accurate prediction of strain, curvature, and internal force evolution over time. The model shows excellent agreement with experimental observations and ABAQUS simulations, accurately capturing deflection trends and crack development. Its performance is further validated using a database of 55 RC beams, including specimens with recycled aggregates and fiber reinforcement. Across this dataset, 84.5% of predicted deflections fall within ±1 mm of measured values, with an R² of 0.960, demonstrating strong reliability. A Sobol-based sensitivity analysis identifies load ratio as the most influential parameter on long-term deflection, followed by concrete strength and humidity. Overall, the model offers an efficient and robust tool for long-term deflection prediction, bridging simplified design rules and complex 3D simulations. Full article

Background/Objectives: Breast cancer is a biologically complex malignancy whose high prevalence and therapeutic resistance represent a continuous challenge for global health. The Tumor Microenvironment (TME) is a crucial component in disease progression, and the Extracellular Matrix (ECM), particularly its 3D collagen architecture, is recognized for mediating interactions that influence invasion, metastasis, and pharmacological response. This review aims to critically synthesize recent evidence to elucidate the multifaceted role of collagen in the progression and modulation of therapeutic response in breast adenocarcinoma. Methods: A comprehensive literature review was conducted, analyzing studies addressing specific collagen subtypes, ECM stiffening (fibrosis), biomechanical signaling, and their impact on drug transport kinetics and immunomodulatory effects. Results: The results demonstrate that structural alterations of collagen not only orchestrate a pro-tumoral microenvironment, fostering aggressive phenotypes and immune evasion, but also create a physical barrier that compromises drug delivery efficiency and promotes metastatic dissemination. The synthesis of the data reinforces collagen as a potent prognostic biomarker and a promising therapeutic target for overcoming stroma-mediated resistance. Conclusions: Targeting the collagen-rich stroma and its 3D network is a critical frontier for therapeutic innovation. Developing adjuvant strategies to modulate the ECM has the potential to enhance clinical outcomes and optimize the distribution of antineoplastic agents, especially in patients with high degrees of tumor fibrosis. Full article

Prestressed concrete (PSC) beams are widely used in bridges and large structures due to their high load-bearing capacity and crack resistance. However, owing to their complex construction process, they are highly sensitive to temperature variations. Implementing temperature monitoring at this stage helps assess the actual mechanical behavior and effective prestress of the beam, providing a reliable basis for construction control and prestress adjustment. This study aims to investigate the mechanical performance of a bidirectionally stiffened composite tensioning and anchoring system developed earlier by the research team during the construction phase and to elucidate the effect of temperature on the mechanical behavior of pretensioned prestressed concrete beams. By deploying a monitoring system integrated with high-precision sensors, synchronized temperature and displacement data during tensioning, pouring, and curing stages were obtained. Field-measured data were used to validate finite element models under different thermal load conditions. The results indicate that the heat of hydration of concrete causes a temperature difference of 12.0 °C at the end form, leading to a maximum displacement of 0.2 mm at the top of the anchor plate. Notably, a temperature change of 22 °C induces a prestress fluctuation of 0.12% to 0.3%. The numerical model demonstrates strong accuracy, with the highest agreement with experimental data and an error of less than 7.5%. These findings provide a scientific basis for compensating prestress losses and controlling the deformation of prestressed concrete beam structures, playing a critical role in ensuring the long-term safety and performance of structures under complex working conditions. Full article

This study presents a mechanics-based comparison of the buckling and ultimate strength behavior of stiffened plates reinforced with bulb-type and built-in angle stiffeners, with particular emphasis on the trade-off between structural performance and weight efficiency. Although these stiffener types are commonly treated as equivalent when designed to provide the same sectional moment of inertia, their nonlinear collapse behavior under realistic loading conditions has not been sufficiently quantified. To address this gap, a two-stage finite element framework is employed, consisting of linear eigenvalue buckling analysis to identify imperfection-sensitive modes, followed by geometrically and materially nonlinear imperfection analysis (GMNIA) to capture post-buckling behavior and ultimate strength. High-fidelity three-dimensional solid models incorporating classification-society-based material properties are used to simulate axially compressed stiffened plates representative of jack-up rig Living Quarter structures. The results demonstrate that, while both stiffener types exhibit comparable elastic buckling resistance, their nonlinear responses differ in terms of stiffness degradation, stress redistribution, and collapse localization. Importantly, the angle stiffener achieves an ultimate strength comparable to that of the elastically equivalent bulb stiffener while requiring less material, thereby exhibiting superior weight efficiency. These findings indicate that elastic equivalence alone is insufficient for optimal stiffener selection and highlight the necessity of nonlinear, imperfection-sensitive assessment in the design of lightweight and high-performance marine structures. Full article

Buried oil and gas pipelines, the critical arteries of global energy infrastructure, are increasingly vulnerable to severe geological hazards such as reverse faulting, yet their structural integrity is often pre-compromised by stochastic corrosion damage accumulated during service. However, quantifying the coupled impact of spatial corrosion heterogeneity and large ground deformation remains a formidable challenge due to the complex nonlinearities involved in soil–structure interactions and wall thinning. This study establishes a probabilistic assessment framework integrating random field theory, nonlinear finite element analysis, and a generative conditional diffusion model to characterize realistic 2D non-Gaussian corrosion morphologies. The numerical results reveal a significant geometric stiffening effect induced by internal pressure, where moderate operating levels effectively suppress cross-sectional distortion by counteracting the Brazier effect. Consequently, this mechanism facilitates a fundamental transition in failure modes from localized tensile rupture to ductile buckling, significantly extending the critical fault displacement threshold. Furthermore, probabilistic fragility analysis demonstrates that the spatial dispersion of pitting, rather than just average wall thinning, governs the initiation of premature failure. Mechanistic analysis indicates that high internal pressure, while providing pneumatic support, exacerbates tensile strain localization at corrosion pits, leading to a heightened probability of premature rupture under minor fault deformations, a critical hazard that traditional deterministic models significantly underestimate. These findings provide a quantitative theoretical foundation for the reliability-based design and maintenance of energy lifelines traversing active tectonic zones. Full article