Search Results (1,463)

Glass fiber-reinforced polymer (GFRP) composites are widely used in structural applications due to their high specific strength and durability; however, their mechanical performance strongly depends on fiber architecture and environmental exposure. This study evaluates the mechanical behavior and moisture-induced degradation of GFRP laminates through tensile tests, impact tests, dynamic mechanical analysis (DMA), and thermomechanical analysis (TMA) performed on a bi-directional glass–epoxy GFRP laminate ([0°/90°]). Tensile tests revealed a maximum longitudinal strength of 369 MPa in dry specimens, while water immersion for up to 21 days led to a significant reduction in tensile strength, from 207 MPa to 63 MPa, in diagonally cut specimens. Impact tests conducted at 12 J showed larger displacements in specimens cut along directions not aligned with the fibers, indicating matrix-dominated behavior. Dynamic mechanical analysis demonstrated strong dependence of stiffness on fiber orientation, with storage modulus values decreasing by approximately 45% in 45° specimens compared with the principal directions, while the glass transition temperature remained within 59–62 °C. Thermomechanical analysis confirmed an increase in the coefficient of thermal expansion after aging, from 205.6 to 291.65 µm/(m·°C) below Tg. These results provide insights into the structure–property–environment relationships governing the durability of GFRP composites and support the optimization of their design for long-term polymer-based applications. Full article

The current study investigates the influence of intersubject variability in ocular characteristics on the mapping of visual field (VF) sites to the pointwise directional angles in retinal nerve fiber layer (RNFL) bundle traces. In addition, the performance efficacy on the mapping of VF sites to the optic nerve head (ONH) was compared to ground truth baselines. Fundus photographs of 546 eyes of 546 healthy subjects (with no history of ocular disease or diabetic retinopathy) were enhanced digitally and RNFL bundle traces were segmented based on the Personalized Estimated Segmentation (PES) algorithm’s core technique. A 24-2 VF grid pattern was overlaid onto the photographs in order to relate VF test points to intersecting RNFL bundles. The PES algorithm effectively traced RNFL bundles in fundus images, achieving an average accuracy of 97.6% relative to the Jansonius map through the application of 10th-order Bezier curves. The PES algorithm assembled an average of 4726 RNFL bundles per fundus image based on 4975 sampling points, obtaining a total of 2,580,505 RNFL bundles based on 2,716,321 sampling points. The influence of ocular parameters could be evaluated for 34 out of 52 VF locations. The ONH-fovea angle and the ONH position in relation to the fovea were the most prominent predictors for variations in the mapping of retinal locations to the pointwise directional angle (p < 0.001). The variation explained by the model (R² value) ranges from 27.6% for visual field location 15 to 77.8% in location 22, with a mean of 56%. Significant individual variability was found in the mapping of VF sites to the ONH, with a mean standard deviation (95% limit) of 16.55° (median 17.68°) for 50 out of 52 VF locations, ranging from less than 1° to 44.05°. The mean entry angles differed from previous baselines by a range of less than 1° to 23.9° (average difference of 10.6° ± 5.53°), and RMSE of 11.94. Full article

This study analyzes the mechanical behavior of a quasi-isotropic biaxial glass fiber–vinyl ester composite in a multiaxial stress condition and the effect of the orientation of the fibers. A ply structure was created through the process of vacuum infusion using six layers of biaxial fabric that were oriented to 15°. Tensile samples were isolated at 0, 15, 30, 45 and 90 degrees relative to the warp direction. It was found that strength and stiffness strongly depend on orientation, with maximum tensile strengths of 157.2 MPa at 90° and 125 MPa at 0°, and minimum tensile strengths 59.6 MPa at 15°, showing fiber and shear failures, respectively. MAT_124 underwent finite element analysis in LS-DYNA, and the results were excellent, with a difference of less than 1.5%. Three-point bending and Charpy impact tests indicated that flexural properties were lower at 15° and 90°, whereas off-axis orientations were generally better at impact energy absorption, although at 45°, binding sites were few and far between. The results have important implications for the design of laminates subjected to complicated loads. Full article

This study evaluates the potential of 3D-printed acrylonitrile butadiene styrene (ABS) and carbon fiber (CF) as sustainable alternatives to steel reinforcement in cement-based materials. The experimental program analyzed the compressive strength of cement pastes and concrete cylinders incorporating 3D-printed ABS and CF elements. Unreinforced cement pastes exhibited higher compressive strength than reinforced pastes, indicating limited reinforcement–matrix interaction. In concrete cylinders, ABS reinforcement increased compressive strength by approximately 3 to 7 MPa compared to steel, whereas CF reinforcement showed variable performance and did not consistently surpass the control specimens. ANOVA and Tukey tests confirmed the statistical significance of the results. The anisotropic response of ABS and CF, inherent to layer-by-layer deposition, was identified as a major factor influencing structural performance, particularly with respect to reinforcement orientation. The results indicate that ABS presents potential as an environmentally favourable alternative to steel in selected applications, while CF requires further optimization for compression-oriented use. Continued research is recommended to evaluate long-term durability, environmental resistance, and reinforcement–matrix compatibility in order to advance the implementation of polymer-based, additively manufactured reinforcements in construction materials. Full article

Ultraviolet (UV) curable resins are widely used in photopolymerization-based 3D printing due to their rapid curing and compatibility with high-resolution processes. However, their brittleness and limited mechanical performance restrict their applicability, particularly in impact-resistant high-performance 3D-printed structures. Inspired by the mantis shrimp’s exceptional energy absorption and impact resistance, attributed to its helicoidal fiber architecture, we developed a Bouligand flax fiber-reinforced composite laminate. By constructing biomimetic helicoidal composites based on Bouligand arrangements, the mechanical performance of flax fiber-reinforced UV-curable resin was systematically investigated. The influence of flax fiber orientation was assessed using mechanical testing combined with the digital image correlation (DIC) method. The results demonstrate that a 45° interlayer angle of flax fiber significantly enhanced the fracture energy of the resin from 1.67 KJ/m² to 15.41 KJ/m², an increase of ~823%. Moreover, the flax fiber-reinforced helicoidal structure markedly improved the ultimate tensile strength of the resin, with the 90° interlayer angle of flax fiber exhibiting the greatest enhancement, increasing from 5.32 MPa to 19.45 MPa. Full article

This work presents the design, modeling, and experimental validation of an innovative, highly autonomous, and economically viable photovoltaic solar cooker, integrating a robust battery storage system. The system combines 1200 Wp photovoltaic panels, a control block with DC/DC power converters and digital control for intelligent energy management, and a thermally insulated heating plate equipped with two resistors. The objective of the system is to reduce dependence on conventional fuels while overcoming the limitations of existing solar cookers, particularly insufficient cooking temperatures, the need for continuous solar orientation, and significant thermal losses. The optimization of thermal insulation using a ceramic fiber and glass wool configuration significantly reduces heat losses and increases the thermal efficiency to 64%, nearly double that of the non-insulated case (34%). This improvement enables cooking temperatures of 100–122 °C, heating element surface temperatures of 185–464 °C, and fast cooking times ranging from 20 to 58 min, depending on the prepared dish. Thermal modeling takes into account sheet metal, strengths, and food. The experimental results show excellent agreement between simulation and measurements (deviation < 5%), and high converter efficiencies (84–97%). The integration of the batteries guarantees an autonomy of 6 to 12 days and a very low depth of discharge (1–3%), allowing continuous cooking even without direct solar radiation. Crucially, the techno-economic analysis confirmed the system’s strong market competitiveness. Despite an Initial Investment Cost (CAPEX) of USD 1141.2, the high performance and low operational expenditure lead to a highly favorable Return on Investment (ROI) of only 4.31 years. Compared to existing conventional and solar cookers, the developed system offers superior energy efficiency and optimized cooking times, and demonstrates rapid profitability. This makes it a sustainable, reliable, and energy-efficient home solution, representing a major technological leap for domestic cooking in rural areas. Full article

Background/Objectives: Poor dietary habits are a major contributor to non-communicable diseases (NCDs), the leading cause of mortality worldwide. To promote healthier eating, governments and stakeholders have implemented various nutrition policies, including front-of-pack nutrition labeling (FOPNL). The Choices International Foundation (Choices), through its criteria, supports these efforts through its standardized nutrient profiling system (NPS). Originally developed to underpin a positive FOPNL logo, in 2021, the criteria were expanded into a globally oriented five-level profiling system covering 23 basic and 10 discretionary food groups, addressing key nutrients such as trans-fatty acids, saturated fat, sodium, sugar, fiber, and energy. To ensure continued scientific relevance, the Choices criteria are periodically reviewed by an independent International Scientific Committee (ISC). Methods: This paper presents the 2025 revision of the Choices criteria, focusing on priority areas identified through stakeholder consultation and recent scientific developments. Results: Key updates include the introduction of nutrient-based equivalence criteria for plant-based alternatives to meat and dairy, based on protein and selected micronutrient thresholds. Non-sugar sweeteners (NSSs) were newly included as a factor that lowers a product’s health classification and makes it ineligible for a positive FOPNL. Additionally, the industrially produced trans-fatty acid (iTFA) criteria were revised and aligned with the latest World Health Organization (WHO) recommendations, improving both technical feasibility and policy coherence. While options for incorporating whole-grain and micronutrient criteria were explored, these were not included in the current revision. Conclusions: The 2025 update system enhances the scientific rigor, policy alignment, and global applicability of the Choices system. By providing a harmonized and evidence-based tool, it aims to support national policies that foster healthier food environments and, ultimately, improve public health outcomes worldwide. Full article

Segment regeneration in earthworms is a remarkable example of postembryonic morphogenesis, yet its fidelity and cellular mechanisms remain incompletely understood. The present study investigated posterior segment regeneration in adult specimens of the earthworm model Eisenia andrei from wound closure to the 5th postoperative week using anatomical, histological, and ultrastructural approaches. Rapid wound closure occurred through fusion of the cut edges of the body wall and midgut without direct involvement of coelomocytes. The regeneration blastema consisted of dedifferentiated epithelial and muscle cells, innervated by fibers from the last intact ventral nerve cord ganglion. Coelomocytes accumulated in the last intact segments and were primarily involved in debris clearance. Notably, early regenerating tissues lacked collagen fibers, which appeared only after the third postoperative week and remained sparse until the fifth week, whereas original segments exhibited intense, region-specific collagen deposition. Transmission electron microscopy revealed characteristic cytological changes in distinct stages of body wall regeneration, including muscle dedifferentiation and the emergence of collagen-producing fibroblasts. These findings indicate that early cell migration, proliferation, and orientation in the blastema proceed independently of collagen and that collagen functions as a delayed structural scaffold, supporting tissue integrity without impeding regeneration. Importantly, no scar formation was observed between old and new tissues, resembling scarless fetal wound healing. Overall, we clarified previously controversial cellular mechanisms and propose a new, comprehensive model for the early stages of segment regeneration. Our results highlight that coordinated dedifferentiation, spatiotemporal extracellular remodeling, and delayed collagen deposition underlie effective, scar-free regeneration in earthworms, offering insights into conserved mechanisms of regenerative repair across metazoans and potential strategies for enhancing tissue regeneration in mammals. Full article

For hot-rolled ferritic stainless steels with preferential α-fiber texture, the strong α-fiber texture is retained after annealing, greatly affecting the texture and plastic formability during the subsequent cold-rolling process. For optimizing the texture of hot-rolled steels toward the favorable γ-fiber type, it is essential to control the annealing temperature in the annealing process. To investigate the evolution of the microstructure, texture, and properties of hot-rolled ferritic stainless steel with preferential α-fiber orientation, a series of annealing tests was performed at the lab scale at 800, 840, 880, 910, 930, and 950 °C for 3 min. The microstructure, texture, and grain boundary characteristics of the tested samples were analyzed using optical microscopy (OM) and electron back-scattered diffraction (EBSD). The mechanical properties and plastic strain ratio (r-value) were determined through universal tensile testing. The results show that at temperatures above 840 °C, more than 93% of recrystallization occurs, leading to significant microstructural refinement. The α-fiber texture intensity typically diminishes with rising temperature, whereas the γ-fiber texture initially weakens during the early stages of recrystallization (below 840 °C) and subsequently exhibits a slight increase at higher temperatures. The improved formability of the material is mainly attributed to microstructural refinement and texture refinement, as reflected by the I(γ)/I(α) texture intensity ratio. At an annealing temperature of 930 °C, the I(γ)/I(α) ratio peaks at 0.85, static toughness is maximized, the strain-hardening exponent (n) reaches a high value of 0.28, and the maximum average plastic strain ratio ($\overline{r}$) is 0.96. This result represents the optimum balance between mechanical properties and formability, making it suitable for subsequent cold-rolling. Full article

Spunbonding drafters play a decisive role in determining fiber attenuation, morphology, and final nonwoven quality; however, their internal airflow behavior remains poorly characterized due to limited physical accessibility and historically empirical design practices. This work employs high-fidelity computational fluid dynamics (CFD) to systematically resolve the airflow field inside a laboratory-scale drafter and to quantify the impact of geometry on fiber drawing conditions. The simulations reveal a previously unreported “braking effect,” where adverse flow structures reduce effective shear drag, limit drawability, and increase the likelihood of fiber breakage. Parametric virtual experimentation across seven geometric variables demonstrates that the drafter configuration strongly governs shear distribution, flow uniformity, and energy consumption. Using a performance-oriented optimization framework, three key processing objectives were targeted: (i) maximizing shear drag to promote stable fiber attenuation, (ii) improving axial drawing uniformity, and (iii) minimizing pressurized-air demand. CFD-guided design modifications—including controlled widening, tailored wall divergence and convergence, and an extensible lower section—were implemented and subsequently validated using a newly constructed prototype. Experimental measurements on polypropylene (PP) and high-density polyethylene (HDPE) fibers confirm substantial reductions in fiber breakage and improvements in drawing stability, thereby demonstrating the effectiveness of simulation-driven process optimization in spunbonding equipment design. Full article

Carbon-reinforced epoxy laminated composite (CREC) structures are increasingly utilized in high-speed marine vehicles (HSMVs) due to their high specific strength and stiffness; however, they are frequently subjected to impact loads like slamming and aggressive environmental agents during operation. This study experimentally investigates the Compression After Impact (CAI) behavior of CREC plates with varying lamination sequences under both atmospheric and accelerated aging conditions. The samples were produced using the vacuum-assisted resin infusion method with three specific orientation types: quasi-isotropic, cross-ply, and angle-ply. To simulate the marine environment, specimens were subjected to accelerated aging in a salt fog and cyclic corrosion cabin for periods of 2, 4, and 6 weeks. Before and following the aging process, low-velocity impact tests were conducted at an energy level of 30 J, after which the residual compressive strength was measured by CAI tests. At the end of the aging process, after the sixth week, the performance of plates with different layer configuration characteristics can be summarized as follows: Plates 1 and 2, which are quasi-isotropic, exhibit opposite behavior. Plate 1, with an initial toughness of 23,000 mJ, increases its performance to 27,000 mJ as it ages, while these values are around 27,000 and 17,000 mJ, respectively, for Plate 2. It is thought that the difference in configurations creates this difference, and the presence of the 0° layer under the effect of compression load at the beginning and end of the configuration has a performance-enhancing effect. In Plates 3 and 4, which have a cross-ply configuration, almost the same performance is observed; the performance, which is initially 13,000 mJ, increases to around 23,000 mJ with the effect of aging. Among the options, angle-ply Plates 5 and 6 demonstrate the highest performance with values around 35,000 mJ, along with an undefined aging effect. Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) analyses confirmed the presence of matrix cracking, fiber breakage, and salt accumulation (Na and Ca compounds) on the aged surfaces. The study concludes that the impact of environmental aging on CRECs is not uniformly negative; while it degrades certain configurations, it can enhance the toughness and energy absorption of brittle, cross-ply structures through matrix plasticization. Full article

Seeds from four landraces of dry beans (Phaseolus vulgaris L. and Phaseolus coccineus L.) from the National Collection of Bulgaria were analyzed for their chemical and lipid composition. The chemical analysis revealed that protein ranged from 24.4% to 31.5%, carbohydrates from 53.1% to 56.1%, fat from 0.9% to 1.4%, fiber from 2.6% to 2.8%, and ash from 3.9% to 4.7%, indicating their high nutritional and caloric value. The seed oils contained significant levels of bioactive compounds, including tocopherols (3483–3809 mg/kg), carotenoids (1664–2049 mg/kg), and phospholipids (24.6–62.2%), which contribute to their health-promoting properties. In the Phaseolus vulgaris accessions, the oil was primarily composed of linolenic (n-3) and linoleic acids (n-6), followed by palmitic and oleic acids, whereas in the Phaseolus coccineus accession, linoleic acid (n-6) predominated, followed by linolenic (n-3) acid. β-Sitosterol was the major sterol, followed by stigmasterol, while the tocopherol fraction was mainly composed of γ-tocopherol (88.2–95.0%), with δ-tocopherol as a secondary component. Phosphatidylcholine was the predominant phospholipid, accounting for 33.1–51.7%. These findings underscore the potential of Bulgarian bean landraces as functional ingredients in health-oriented food products due to their balanced nutritional profile and presence of bioactive lipids. Full article

Incorporating coarse aggregates into ultra-high-performance concrete (UHPC-CA) can reduce material costs, yet reliably predicting its strength-related behavior and overall performance remains challenging. This study examines UHPC-CA through a two-stage orthogonal experimental program comprising 18 mixtures with coarse aggregate, fly ash, and hybrid fiber reinforcements (steel, polypropylene, and composite fibers). Microstructural characterization using scanning electron microscope (SEM) and X-ray computed tomography (X-CT) was conducted to assess interfacial features and crack evolution and to link these observations to the measured mechanical response. Experimentally, fiber reinforcement markedly enhanced post-cracking performance. Compared with the fiber-free control mixture, the optimal hybrid configuration increased flexural strength from 6.9 to 23.5 MPa and compressive strength from 60.1 to 90.5 MPa. The steel–composite fiber system outperformed the steel–polypropylene system, which is consistent with the tighter composite-fiber interfacial bonding observed by SEM/X-CT and supports the feasibility of partially substituting steel fibers. An artificial neural network (ANN) model trained on 50 mixtures and evaluated on 10 unseen mixtures achieved an R² of 0.9703, an MAE of 1.22 MPa, and an RMSE of 2.11 MPa for compressive strength prediction, enabling sensitivity assessment under multi-factor coupling. Overall, the proposed experiment–characterization–modeling framework provides a data-driven basis for performance-oriented mix design and rapid screening of UHPC-CA. Full article

The urgent need for sustainable innovation in the construction industry necessitates a reevaluation of how architecture engages with materials and fabrication processes. This paper introduces tailored fiber placement (TFP) as a novel fabrication method with significant potential for advancing sustainable architectural practice. Originally developed for aerospace and automotive applications, TFP enables stress-oriented fiber alignment, offering precision, material efficiency, and lifecycle-conscious design opportunities. To articulate these capabilities, the paper examines four case studies at multiple scales. Ranging from small-scale seating to medium-scale façade components, these examples demonstrate TFP’s ability to enable mold-less forming and integrative fabrication in support of sustainable construction. Through digitally programmed fiber orientations, the cases achieve both structural and geometric requirements while minimizing waste and improving workflow efficiency. This research positions TFP as a material-aware and performance-driven approach to sustainable architectural production. By bridging material, design, and fabrication, TFP contributes to more circular, adaptable, and efficient construction systems. Full article

In this study, we developed a method for creating an active layer based on a composite material consisting of chitosan and an anisotropic network of nickel fibers (Chitosan/Ni + NiFs). Using this chitosan biopolymer matrix and anisotropic network, we achieved a high specific surface area for the catalytic material, high lateral conductivity for the layer, and stable characteristics, ultimately leading to increased overall electrocatalytic activity in the hydrogen evolution reaction (HER). Through linear voltammetry and impedance spectroscopy, we identified the mechanism and kinetics of the HER in the developed system. The overpotential of the electrochemical reaction was 213 mV at a current density of 10 mA/cm². Chromatographic analysis confirmed the effectiveness of the Chitosan/Ni + NiFs system in the HER. Our results show how the chitosan biopolymer matrix and oriented nickel fiber network influence charge transfer and electrode reactions, as reflected in the activation energies of hydrogen bonds on the electrocatalytic layers. These findings show that it is feasible to combine a biopolymer matrix and an anisotropic nickel fiber network to create effective electrocatalysts. This approach enables the development of environmentally friendly electrolytic hydrogen production technologies. Full article