Search Results (20,764)

Metal–polymer hybrid joints are gaining importance as they combine high structural rigidity with a low weight. Additive manufacturing processes such as the laser powder bed fusion process (L-PBF) enable the production of complex metallic lattice structures that allow for form-fitting force transmission between the metal and polymer as mechanical interlock elements. In this work, metal–polymer hybrid compounds with additively manufactured transition zones are systematically investigated and mechanically evaluated. Three different lattice geometries (z4A, z8A, z8V) were fabricated from maraging steel (1.2709) using L-PBF and then hybridised with injection moulding using polypropylene (PP C7069-100NA). Mechanical characterisation was performed by tensile tests according to DIN EN ISO 527, in combination with statistical analyses and an analytical serial three-spring model to determine the homogenised elasticity modulus of the transition zone. The results show significant geometry-related differences in tensile strength, maximum force, and effective stiffness. The A-shaped transition zone geometry (z4A) achieves the highest mechanical performance and up to 82% of the tensile strength of the pure polymer, while the V-shaped transition zone geometry (z8V) has significantly lower load-bearing capacities. Variance analysis shows a dominant geometric influence with effect strength of η² ≈ 0.99. The analytically predicted stiffness values match the experimental results within 5–10%. This work demonstrates a reproducible, simulation-sparse approach to the analysis and design of metal–polymer hybrid connections. Full article

Background and Clinical Significance: To our knowledge, there is a lack of electron microscopy studies in hematocornea since 1985, and more so for graft hematocornea after deep anterior lamellar keratoplasty (DALK). This study provides an ultrastructural characterization of hematocornea occurring in a DALK graft. Our study presents several limitations: single-case design and lack of control tissue. Case Presentation: The DALK graft with hematocornea was excised and introduced inside of the operating room in glutaraldehyde solution recipient. The graft was quickly cold-transported to light and transmission electron microscopy. Hematocornea in the DALK transplant graft resulted in features of stromal alteration and dysfunctional cellular clean-up response. The collagen lamellae ultrastructure was affected near electron-dense hem deposits. Two cellular aspects were observed: adaptation and degeneration. Electron-dense granules were found in keratocytes, which may exhibit cellular adaptations, such as vacuoles and phagosomes. Macropinocytosis may mechanistically explain ingestion of electron-dense granules, and dysfunctions in the macropinocytosis process may have led to cell degeneration. Cellular degeneration was marked by loss of organelle contour and loss of cellular membrane integrity (burst-cell aspect). Microscopic corneal alteration corresponded to macroscopic total loss of corneal transparency and elasticity. Conclusions: This study described lamellar ultrastructure alterations and dysfunctional cellular response in hematocornea of a DALK corneal transplant graft. Full article

The research gap addressed in this study is the lack of a transparent and quantitative evaluation of the governing parameters influencing deflection behavior in reinforced concrete (RC) beams reinforced with glass fiber-reinforced polymer (GFRP) bars. The objective of this study is to identify and quantify the relative importance of the key parameters controlling deflection in GFRP-reinforced RC beams, which exhibit fundamentally different behavior compared to steel-reinforced beams due to the linear-elastic response of GFRP bars until rupture. To achieve this objective, the method integrates explainable artificial intelligence (XAI) techniques, including SHapley Additive exPlanations (SHAP), Pearson correlation heatmap, scatter plot analysis, and sensitivity analysis—with experimental structural data obtained from beams with three different concrete strength classes. The main contribution of this study is the quantitative ranking and interpretation of the governing parameters affecting deflection behavior through a transparent and data-driven framework. Key parameters—including elastic modulus (Ec), compressive strength (fck), creep coefficient (φ), failure moment (Mexp), effective moment of inertia (Ieff), and applied load (P)—were evaluated. The results consistently indicate that stiffness- and capacity-related parameters dominate the deflection response. Sensitivity analysis reveals that the failure moment (Mexp) is the most influential parameter, contributing approximately 23% of the total relative influence on deflection, followed by compressive strength (fck) and cracking-related parameters. Pearson correlation heatmap and scatter plot analyses further confirm strong relationships between deflection and Ec, fck, φ, and Ieff. The proposed framework improves the interpretability of deflection prediction in GFRP-reinforced RC beams and provides a transparent basis for serviceability-based structural design and performance-oriented assessment. Full article

Chronic diabetic wounds are challenging to treat due to persistent inflammation, oxidative stress, impaired angiogenesis, and dysregulated matrix remodelling. Hydrogen sulphide (H₂S) has emerged as a therapeutic mediator with antioxidant, anti-inflammatory, and pro-angiogenic properties; however, its clinical translation is limited by volatility and a short biological half-life. Controlled delivery systems, such as hydrogels, are therefore required to harness its potential. This study aimed to develop and evaluate a sodium 2-acrylamido-2-methylpropane sulfonate (Na-AMPS)-based adhesive hydrogel incorporating AP39, a mitochondria-targeted H₂S donor, for sustained localised delivery and promotion of wound healing. Hydrogel formulations were characterised for rheological behaviour, adhesion, swelling, and AP39 release. Cytocompatibility was assessed in human umbilical vein endothelial cells (HUVECs); human dermal fibroblasts, adult (HDFa); and keratinocytes. Anti-inflammatory, antioxidant, and matrix-modulatory effects were evaluated via interleukin-6 and 8 (IL-6/IL-8) secretion, reactive oxygen species (ROS) levels, mitochondrial membrane potential, matrix metalloproteinase-9 (MMP-9), and transforming growth factor-beta (TGF-β). Functional wound healing activity was assessed using tube formation and scratch assays in endothelial cells. AP39-loaded hydrogels exhibited predominantly elastic, shear-thinning behaviour, strong adhesion, rapid hydration, and sustained release of AP39 (11.63 ± 1.20% over 24 h). Across all cell types, 500 nM concentrations of AP39 were well tolerated. In diabetic-like stress conditions, AP39 significantly decreased ROS in HUVECs (50122 ± 5999 to 33,087 ± 1865 AU; p < 0.0001) and HDFa cells (41,367 ± 4225 to 29,813 ± 2406 AU; p < 0.0001). AP39 improved mitochondrial membrane potential in both cell types (p < 0.01–0.001) and decreased pro-inflammatory cytokines. IL-6 decreased in HUVECs (96.05 ± 4.22 pg/mL to 60.99 ± 4.21 pg/mL; p < 0.0001) and HDFa cells (77.54 ± 8.94 pg/mL to 52.25 ± 6.78 pg/mL; p < 0.001), whilst in HDFa cells, MMP-9 was reduced (419.4 ± 25.51 pg/mL to 174 ± 15.1 pg/mL; p < 0.0001). Finally, wound closure was enhanced in HUVECs. The AP39-loaded Na-AMPS hydrogel represents a multifunctional wound dressing capable of controlled H₂S delivery, mechanical stability, and biological activity to support tissue repair in diabetic wound environments. These results highlight this gel’s therapeutic potential for diabetic wound treatment. Full article

Laser processing has been widely investigated as an effective approach for improving surface properties and consolidating advanced materials, particularly complex alloys such as titanium aluminides (TiAl). In this study, laser surface remelting was applied to binary (Ti-45Al) and ternary (Ti-45Al-2Co and Ti-45Al-2Ni) alloys produced by powder metallurgy via blended elemental (BE) and pre-alloyed (PA) powder routes. Laser powers of 50 and 100 W were employed, resulting in a high-energy-density surface remelting regime applied to both green compacts and sintered samples with relatively high initial porosity, under an argon-controlled atmosphere. Microstructural and phase analyses were performed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), while mechanical behavior was assessed by instrumented microindentation. Laser processing promoted the formation of a dense and homogeneous surface layer, approximately 150 μm thick, accompanied by significant microstructural refinement and enhanced hardness and elastic modulus. While rapid solidification led to crack formation in laser-treated sintered samples, the green compacts exhibited defect-free modified layers. Overall, the results demonstrate that laser surface remelting is an effective strategy for enhancing the surface integrity and mechanical performance of TiAl alloys processed by powder metallurgy. Full article

Hydrogen-induced crack growth initiation, in metallic structures, is studied under constant temperature and chemical equilibrium, by employing Chemical Equilibrium Fracture Mechanics (CEFM). The conditions of small-scale, contained and large-scale hydrogen embrittlement are introduced and the areas of material deterioration, together with the distributions of stress and hydrogen concentration, including hydride volume fraction, are derived analytically. It is shown that the shape of the material deterioration zone is identical for embrittlement caused either by hydrogen in solid solution or by hydride precipitation; the size depends on the strength of the asymptotic crack-tip field, which develops by the mechanical loading in the hydrogen-free structure, as well as on the average hydrogen content absorbed by the structure. It is also shown that a linear relation exists between a power of the threshold of crack-growth initiation and the logarithm of hydrogen content, depending on the extent of hydrogen embrittlement and material elastic-plastic deformation. These linearity trends, which are derived by the present analysis, are confirmed by published experimental fracture mechanics measurements on several non-hydride- and hydride-forming alloys, including α/β hydride-forming alloys. The present study promotes structural integrity assessments, without reliance on complicated coupled numerical analysis of material deformation, hydrogen diffusion and hydride precipitation. Full article

Carbonate reservoirs in the Shunbei area develop pronounced fracture networks after acidized hydraulic fracturing and thus have the potential to be repurposed as underground gas storage (UGS) after hydrocarbon depletion. Characterizing their mechanical behavior is essential for safe UGS operation; however, deep to ultra-deep natural cores are difficult to obtain, and conventional macroscopic tests often cannot provide parameters that meet engineering requirements. To address this issue, nanoindentation combined with QEMSCAN (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) was employed to quantify microscale mineral distributions and the mechanical properties of the major constituents. The investigated rock is calcite-dominated (89.62%), with minor quartz (9.89%) and trace feldspar-group minerals (1.89%). Minerals are randomly embedded, and soft–hard phase boundaries are widely distributed. A finite–discrete element method (FDEM) model was then constructed and calibrated in ABAQUS. The discrepancies in uniaxial compressive strength and elastic modulus relative to laboratory results were 6.51% and 9.91%, respectively, indicating good agreement in both mechanical response and failure mode. Parametric analyses using three additional models with different mineral proportions show that damage preferentially initiates at mineral phase boundaries and stress concentration zones induced by end constraints. Microcracks then propagate and coalesce into a dominant compressive–shear band, and final failure is mainly governed by slip along the shear band with localized tensile cracking. With increasing quartz and feldspar contents, enhanced heterogeneity and a higher density of phase boundaries lead to a higher density of crack nucleation sites and increased crack branching, and the failure pattern transitions from a single shear-band–controlled mode to a more network-like fracture system. Moreover, macroscopic strength is not determined solely by the intrinsic strength of individual minerals; heterogeneity and phase-boundary characteristics strongly govern microcrack behavior, such that higher hard-phase contents may result in a lower peak strength. Full article

This study investigates the utilization of Abies alba exudate resin for the development of hybrid resins intended as matrices for composite materials. The novelty of this work lies in demonstrating that physically hybridized, bio-derived resin systems based on Abies alba exudate can exhibit distinct mechanical and dynamic behaviors solely by adjusting the solvent-assisted formulation route, without intentional chemical modification and without spectroscopic evidence of co-network formation within the limits of ATR-FTIR analysis, although limited interfacial interactions cannot be excluded. Two formulation routes were explored: (i) dilution of Abies alba exudate in turpentine derived from pine buds, (ii) dilution in ethanol (96%). The diluted resins were subsequently blended with a commercial epoxy system, which was cured with its amine hardener to form solid matrices in which the Abies alba component was physically incorporated. The resulting hybrid resins were characterized by multiple testing methods and further applied in the fabrication of cotton fiber-reinforced composites. The turpentine-based hybrid resin (HR1) showed a rigid mechanical response, with tensile strengths of approximately 13.2–13.5 MPa, compressive strengths of about 30 MPa, Shore D hardness values of 56–58.5, and a low damping ratio (≈0.026). In contrast, the ethanol-based hybrid resin (HR2) exhibited a highly deformable mechanical response, characterized by low tensile strength (≈0.5 MPa), very high elastic recovery, low hardness (<10 Shore D), and a significantly higher damping ratio (≈0.139). To demonstrate their applicability in composite manufacturing, the HR1 matrix was reinforced with cotton fabric, leading to a substantial improvement in tensile strength (25–26 MPa) and flexural strength (35–36 MPa), together with an increased natural frequency. Water absorption tests revealed limited moisture uptake for the neat hybrid resins (≤0.04 g), while the cotton-reinforced composite exhibited higher but largely reversible water absorption (≈21.5%), associated with the hydrophilic nature of the reinforcement. Full article

The mechanical behavior of deep rock masses under high-stress conditions exhibits significant nonlinear characteristics. However, current in situ stress field inversion methods typically rely on linear elastic constitutive models and multiple linear regression analysis. By analyzing the results of triaxial stress–strain tests and confining pressure calibration experiments on rocks, and drawing on the nonlinear concepts from the Duncan-Zhang model, a nonlinear characterization function was developed, represented by mean stress p, bulk modulus K, and shear modulus G. The nonlinear elastic constitutive model was integrated into a numerical simulation framework, and a new in situ stress field inversion fitting method based on nonlinear elastic constitutive modeling was proposed. This method uses initial linear iterations followed by multiple nonlinear iterations until convergence is achieved. Applied to the inversion of the deep in situ stress field at the Xishan Iron Mine, the results demonstrate that compared to traditional linear regression-based methods, the errors in mean stress, deviatoric stress, and the Lode parameter were reduced by 58%, 50%, and 22%, respectively, confirming the effectiveness of this method in in situ stress field inversion in rock mechanics. Full article

This study examines how zoning regimes mediate the capitalization of officially assessed land values into housing prices in a high-density metropolitan housing market. Using transaction-level housing data from New Taipei City, Taiwan, we estimate a hedonic pricing model combined with a boundary-based spatial comparison that restricts observations to properties located near zoning borders. The results indicate that official land values are significantly associated with housing prices but are only partially capitalized, with an estimated elasticity of approximately β ≈ 0.37 in the baseline specification. Interaction models further reveal that capitalization elasticities vary systematically across zoning regimes, suggesting that planning regulations influence how administratively determined land values are translated into market prices. These heterogeneous capitalization patterns remain stable across alternative boundary bandwidths and model specifications. The findings highlight the institutional role of zoning systems in shaping the relationship between administratively assessed land values and housing market outcomes. More broadly, the study contributes to the literature on housing market regulation by demonstrating how land-use institutions mediate price formation processes in densely developed urban environments. Full article

Background: Non-surgical procedures utilizing microcurrent radiofrequency (RF) represent a non-invasive option for patients experiencing skin laxity and loss of firmness due to aging, hormonal changes, or weight fluctuations. Such treatments benefit individuals seeking both preventive measures to delay visible aging and corrective approaches to improve existing skin laxity without invasive surgery. The Plasma IQ medical device generates microcurrent RF energy that produces controlled heating, leading to targeted tissue ablation and subsequent remodelling. This study aimed to evaluate the clinical efficacy of Plasma IQ in the treatment of skin laxity. Materials and Methods: Thirty patients presenting with facial skin laxity and photodamage underwent treatment with the Plasma IQ device. Clinical outcomes were assessed prior to the procedure and at 7, 21 and 90 days post-treatment. Results: RF treatment produced a measurable improvement in skin elasticity (+22.51%). The distance between the upper eyelid margin and the beginning of the eyelid fold increased by 2.01 mm (+46.94%) at day 21 and by 2.11 mm (+49.11%) at day 90. Conclusions: Microcurrent RF delivered by the Plasma IQ device is an effective non-invasive method for periocular skin rejuvenation. The treatment improves skin elasticity, reduces wrinkles around the eyes, and increases the visible distance between the upper eyelid margin and fold, thereby enhancing upper eyelid definition. Full article

Elastic cloud systems are increasingly employing machine learning (ML) to automate resource scaling in response to variable workloads and stringent service-level objectives. However, current ML-based autoscalers are fragmented across different platforms, objectives, and evaluation frameworks. This survey examines 60 primary studies conducted between 2015 and 2025, categorising them according to a five-dimensional taxonomy that includes goal, decision logic, scaling mode, control scope, and deployment. This study classifies supervised, unsupervised, and reinforcement learning approaches and analyzes their integration into practical frameworks, including Kubernetes-based controllers and cloud provider services. This paper summarizes the application of machine learning to workload prediction, proactive and hybrid horizontal–vertical scaling, and adaptive policy optimization. Additionally, it synthesises common evaluation practices, encompassing workloads, metrics, and benchmarks. The analysis identifies ongoing challenges: actuation delays and telemetry lag, the intricacies of hybrid scaling, coordination across multi-service and edge-cloud deployments, and the constrained joint consideration of cost, SLO, and energy objectives. The identified gaps necessitate additional research on unified machine learning-driven orchestration, multi-agent and federated control, standardised benchmarks, and sustainability-aware autoscaling. Full article

The growing pollution caused by plastics with slow degradation kinetics is demanding the search for biodegradable alternatives. Starch-based films are a promising option, but their practical application may be limited by their potential susceptibility to rapid ultraviolet (UV) exposure degradation. This study evaluates the effect of prolonged UV-C irradiation (254 nm, 168 h) on plasticizer-free films derived from the starch of an Ecuadorian potato Solanum tuberosum (Chola variety). Films formulated at 3% and 5% (w/v) starch were characterized before and after UV exposure. The analysis includes the evaluation of optical, mechanical, and physicochemical properties, along with Fourier Transform Infrared spectroscopy (FTIR) and atomic force microscopy (AFM) for nanoscale surface inspection. UV irradiation increased the opacity of the films but reduced slightly their tensile strength, elongation at break, moisture content, and total soluble matter. In contrast, the elastic modulus remained relatively high. FTIR analysis revealed no significant formation of new functional groups. AFM measurements indicated that irradiation caused only minor nanoscale alterations in the same film regions. These alterations were more pronounced in films with higher starch concentrations. The results demonstrate that UV-C exposure induces minor structural adjustments in plasticizer-free starch films derived from the Chola variety, without compromising their fundamental integrity. Consequently, this work advances the understanding of the environmental stability of these films and supports their potential application as sustainable materials, even in conditions involving UV exposure. Full article

To elucidate the degradation behavior of elastic modulus in normal-strength ordinary concrete under flexural fatigue loading, this study systematically examines its evolution in C50 concrete, which is widely used in engineering applications. Based on four-point bending fatigue test data of plain concrete (PC) and reinforced concrete (RC) beams, degradation curves of the relative residual elastic modulus as a function of the cycle ratio were established. To quantitatively characterize the fatigue degradation process, two integrated indicators—the area under the curve (AUC) and the stable-stage degradation slope (|$K_{mid}$|)—were introduced to represent the degree of cumulative damage and the degradation rate of elastic modulus, respectively. These indicators were subsequently employed to evaluate the effects of maximum stress level, stress ratio, and reinforcement on elastic modulus degradation. The results show that failed PC specimens exhibited a typical three-stage S-shaped degradation pattern, whereas RC specimens primarily exhibited a two-stage degradation behavior. However, the elastic modulus of runout PC specimens remained above 93% of its initial value throughout the entire loading process. For PC specimens, under the same maximum stress level, increasing the minimum stress level from 0.10 to 0.25 resulted in a 24% decrease in |$K_{mid}$| from 0.2505 to 0.1912. At the same minimum stress level, increasing the maximum stress level from 0.75 to 0.90 led to a 94% increase in |$K_{mid}$| from 0.1912 to 0.3705. The presence of reinforcement increased AUC by 3~15% and reduced |$K_{mid}$| by 54~74%, indicating that reinforcement not only mitigated overall damage accumulation but also significantly slowed the degradation rate of the elastic modulus during the stable fatigue stage. The degradation characterization approach proposed in this study provides a simplified and practical framework for fatigue analysis of concrete components based on damage mechanics. Full article

This study investigates the development of workwear designed to withstand harsh conditions and support physically demanding tasks. Its central aim is to create garments that enhance workers’ comfort and mobility by optimizing ergonomic and anthropometric factors. First of all, expert surveys were collected, and the importance of posture adaptability and material comfort was highlighted. To investigate realistic body–garment interactions, the 3D body scans of the upper body from 34 participants in common working poses were captured. These scans revealed the zones of high deformation, guiding the placement of elastic inserts to improve flexibility in targeted areas. The redesigned garments underwent a two-stage evaluation process. First, Clo3D virtual fittings provided qualitative insights into overall jacket fit and movement behavior. Next, stress and strain mapping offered quantitative validation, showing that fabric stress levels remained below 120 kPa, providing evidence that the added elasticity effectively reduced mechanical load and improved wearability. Expert reviewers confirmed the enhanced fit and functional performance. Overall, the study demonstrates an integrated design strategy that unites textile behavior, body dimensions and biomechanics. This approach not only improves workwear but also offers a transferable framework for developing specialized clothing across other physically intensive professions. Full article