Search Results (11,286)

Waste prevention is at the top of the EU Waste Framework directive hierarchy. With this in mind, this article considers the application of novel technologies in the Cultural Heritage Restoration and Conservation field through environmental and circular economy principles. While previous research has explored the use of wood waste for composite materials such as building insulation and concrete additives, the suitability of degraded historical wood waste for filament production and 3D printing has not yet been addressed. This article contributes to this topic by studying the PLA/wood composite, material composed of a polylactic acid (PLA) polymer matrix reinforced with wood particles, produced from degraded historical construction materials. The paper describes the process of producing filament from bio- and moisture-damaged pine beam and oak parquet, followed by the 3D printing of historical platband replica. Research methods include photogrammetry, filament machine construction, filament production and 3D printing. The machines settings used in the process: heater temperatures were set to 140 °C, 90 °C and 105 °C; servo speed was 33 s; spool tension was 12.5; winding speed was 24 RPM; and screw speed was 9.2 RPM. For material preparation, a mixture containing 25% pine and oak sawdust and PLA dust was processed to achieve particle sizes of 312 μm, 471 μm, and 432 μm, respectively. Filament production was carried out with diameters of 2.85 mm for the pine/PLA composite and 1.75 mm for the oak/PLA composite. Finally, replica samples were fabricated using 3D printing. The dual objective of this research was to develop the method of 3D printing from degraded historical materials and introduce it to restoration practice as a wood waste minimization technique. Perspectives for further study include the testing of 3D-printed construction materials in outdoor conditions, and pellet production to achieve a higher wood content, compared to the filament thread. The processes described are adaptable to a variety of materials and disciplines. Full article

Surface finishing processes are required to produce the final shape of components made of the silicon-infiltrated silicon carbide composite Cesic^® from ECM (Engineered Ceramic Materials GmbH, 85452 Moosinning, Germany). Electrical discharge machining (EDM) is still the most effective method for manufacturing pockets and mounts in 3D-shaped ceramic satellite components for space applications. NC-grinding is not used, because it results in high grinding loads and rapid tool wear when applied to Cesic^®. In contrast to planar machining, tool wear during NC-grinding with small tools is particularly critical, as it alters the tool geometry and consequently causes deviations in the workpiece geometry. Ultrasonic-assisted grinding offers a promising alternative to overcome the low material removal rates and long processing times associated with EDM while simultaneously enhancing tool life, thus enabling more economical and reliable production. In this experimental study, both conventional grinding (CG) and ultrasonic-assisted grinding (UAG) processes are compared and used to machine Cesic^®. In order to verify the effect of the ultrasonic vibration, analyses of amplitude and frequency are performed. During machining experiments, the grinding loads are measured. The influence of different machining conditions on surface quality is evaluated concerning the roughness of the machined specimens. Compared to CG, UAG shows lower tool wear, owing to the self-cleaning effects caused by the ultrasonic oscillation of the tool. Consequently, the stability of the NC-grinding process is significantly improved. Full article

Geomagnetic storms can severely disturb the ionosphere, degrading Global Navigation Satellite System (GNSS) performance, particularly at low latitudes. The 10 May 2024 superstorm produced a strong ionospheric response across Mexico, with well-defined positive and negative phases observed at all analyzed stations. The proximity in time of %dTEC peaks to the second and third steps of the storm’s main phase, together with their local time dependence, indicates that Prompt Penetration Electric Fields (PPEFs) dominated the initial positive phase on the dayside. These eastward electric fields uplifted the F-region plasma, enhancing TEC values—especially at northern stations, where increases reached ±180%. In contrast, the subsequent nighttime depletion and extended recovery were mainly driven by composition-related plasma loss and enhanced recombination. A suppression of TEC followed the positive phase, with depletions between −58% and −77%, showing a persistent latitudinal gradient. Low-cost GNSS receivers successfully captured these ionospheric signatures but exhibited higher positioning degradation—up to 50% greater than geodetic-grade receivers. Multi-constellation Precise Point Positioning (PPP) mitigated these effects, reducing 3D errors by up to 23% and 53% in geodetic and low-cost receivers, respectively. These findings reveal the day–night dependence of ionospheric storm phases and underscore the importance of regional multi-GNSS monitoring during extreme space weather. Full article

This study investigates the mechanical performance of squeezed branch piles under combined loads (horizontal combined with uplift/compression) in silty clay through model tests. Based on a systematic comparison of the mechanical responses among straight-shaft piles, single-plate piles, and double-plate piles, the load-dependent behavior of branched piles is revealed, and optimized design principles are proposed. The results demonstrate that under horizontal combined loads, squeezed branch piles effectively mobilize soil-arching effects via the bearing plates, leading to significant enhancements in both horizontal and vertical-bearing capacities compared to straight-shaft piles. Double-plate piles exhibit superior overall deformation resistance due to composite confinement; however, an adverse superposition effect at a plate spacing of 2 d may result in a marginally lower capacity. The horizontal capacity of single-plate piles increases with embedment depth, with the axial force peaking at a critical depth of 4 d (embedment depth of first plate). The upper plate plays a dominant role in resisting deformation, consistently carrying 75–105% higher axial force than the lower plate. This research provides important theoretical support and practical references for the design of pile foundations subjected to complex loading conditions. Full article

The increasing demand for sustainable substrates in agriculture and urban greening calls for alternatives to peat, whose extraction poses significant environmental risks. This study assesses the potential of olive pomace biochar (OB), wood biochar (WB), and green compost (GC), alone or in combination, to partially replace peat in growing media and improve substrate properties and plant development. Ten different substrates were formulated by substituting 10–20% of a commercial peat-based substrate with these organic amendments, using the commercial substrate alone as a control. The effects of such replacements were evaluated in the following experiments: a germination test conducted in Petri dishes using four forage species (Medicago polymorpha, Lolium perenne, Festuca arundinacea, and Lolium rigidum); and two parallel pot experiments lasting 100 days each (one with M. polymorpha and L. perenne, and another with young Olea Europaea var. Arbequina saplings). This study evaluated the impact on plant development, as well as the physical properties and composition of the substrates during the incubation process. Germination and survival of forage species were comparable or improved in most treatments, except those including 20% OB, which consistently reduced germination—likely due to high electrical conductivity (>10dS/m). In the pot experiments, substrate pH and total carbon content increased significantly with biochar addition, particularly with 20% WB, which doubled total C relative to control. Both forage species (Medicago polymorpha and Lolium perenne) and the olive saplings (Olea Europaea) exhibited normal growth, with no significant differences in biomass, water content, or physiological stress indicators when compared to the control group. Nutrient uptake was found to be stable across treatments, although magnesium levels were below sufficiency thresholds without triggering visible deficiency symptoms. Overall, combining compost and biochar—particularly WB and GC—proved to be a viable strategy to reduce peat use while maintaining substrate quality and supporting robust plant growth. This approach proved effective across the different plant varieties tested, including Medicago polymorpha, Lolium perenne, and young olive plants, which together encompass a wide spectrum of agronomic and horticultural applications as well as contrasting growth and nutrient requirements. Adverse effects on early plant development can be avoided by carefully selecting and characterizing biochars, with specific attention to salinity and C/N ratio. This finding is crucial for the successful large-scale implementation of sustainable alternatives to peat. Full article

Yeast culture (YC) is widely used in dairy production to enhance milk yield and quality, yet effects vary due to differences in products, doses, and trial conditions. This meta-analysis evaluated the impact of YC supplementation on milk yield and composition in lactating Holstein cows, aiming to identify effective yeast culture types, dosages, and duration of use. A systematic search of PubMed, Web of Science, and CNKI for randomized controlled trials (RCTs) from 2000 to 2024 was conducted. Following PICOS criteria, 23 RCTs comprising 32 comparisons and over 3200 cows were included. Data were analyzed using RevMan 5.3 and Stata/MP 15.0 to compute standardized mean differences (SMD) and 95% confidence intervals with random-effects models. Subgroup and sensitivity analyses were performed. Results showed that YC supplementation significantly improved milk yield (SMD = 2.14), fat (SMD = 0.57), protein (SMD = 1.34), and lactose content (SMD = 0.61). Subgroup analysis revealed that supplementation with saccharomyces cerevisiae at a dosage of 10–50 g/d effectively increased milk yield during lactation 42–56 d. In contrast, during the lactation 21–30 d, different dosages of saccharomyces cerevisiae exerted differential effects on milk composition: supplementation at 60–120 g/d contributed to an increase in milk fat content, while supplementation at 10–50 g/d significantly enhanced milk protein level. Furthermore, lactose content was not significantly associated with the feeding period of saccharomyces cerevisiae; however, high-dose (>120 g/d) could significantly increase lactose content. Significant heterogeneity (I² = 70.7–89.6%) was observed, largely due to strain and dose variations. In conclusion, YC effectively enhances milk production and composition, with optimal outcomes depending on yeast type, dose, and duration, providing evidence-based recommendations for targeted supplementation strategies. Full article

This study investigated the individual and synergistic impacts of arbuscular mycorrhizal fungi (AMF) inoculation and foliar-applied silicon nanoparticles (SiNPs) on the yield parameters, volatile profile, and phenolic composition of two Rosa damascena genotypes (D231 and C193). Experiments were conducted using a split–split–plot design, involving AMF inoculation (main plot), three SiNPs concentrations (subplot), and two rose genotypes (sub-subplot). The results demonstrated that AMF, SiNPs, and genotype all had significant and interactive effects on flower yield parameters. Foliar application of SiNPs, particularly when combined with AMF inoculation, consistently enhanced flowering parameters, including flower size, number, and weight across both genotypes. High-performance liquid chromatography (HPLC) further confirmed that phenolic acids (vanillic acid and rutin) increased following foliar application of SiNPs and AMF root colonization, particularly in genotype C193. SPME-Arrow analysis revealed that alcohols, ketones, and terpenes were the predominant volatile constituents. Phenethyl alcohol was the most abundant compound, accounting for approximately 84.69% of the total aroma content and contributing significantly to the ‘rose’ aroma. Other major volatiles included 2-undecanone (4.42%), benzyl alcohol (2.97%), and citronellol (1.95%); however, their levels varied depending on treatment and genotype. These findings highlight that the combined application of AMF and SiNPs offers a sustainable approach to enhancing both the quantitative yield and qualitative phytochemical composition (essential oil components and phenolic compounds) of R. damascena, providing a scientific foundation for optimizing its production in organic farming systems. Full article

Background/Objectives: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have emerged as a transformative therapy for obesity and type 2 diabetes (T2D) in pediatric populations. This review synthesizes current evidence on efficacy, safety, and knowledge gaps in children and adolescents. Methods: A structured review of randomized controlled trials, extension studies, and mechanistic investigations evaluating GLP-1RAs in pediatric obesity and T2D was conducted. Outcomes of interest included body weight, BMI, body composition, glycemic control, and adverse events. Results: In adolescents, liraglutide and semaglutide consistently produce clinically meaningful reductions in BMI, body weight, and waist circumference, with modest improvements in systolic blood pressure and minimal effects on lipid levels or HbA1c. A newer trial in children 6 to <12 years showed liraglutide reduced BMI compared with placebo, with GI events consistent with prior safety profiles. Weight loss tends to include both fat and lean components; rapid weight loss may impair muscle strength or bone density if resistance exercise and adequate protein intake are not ensured. Risks include micronutrient gaps, misuse, and uncertain long-term effects on growth and puberty. These important considerations remain largely unaddressed in pediatric studies, and adult data can’t be directly extrapolated to children due to developmental, hormonal, and physiological differences. Conclusions: GLP-1 RAs are a promising adjunct to lifestyle therapy for pediatric obesity, but pediatric-specific protocols are needed to safeguard musculoskeletal health, ensure nutritional adequacy, and minimize misuse. Critical gaps remain in pediatric pharmacokinetics, dosing strategies, and long-term developmental safety. Further research is essential to develop evidence-based guidelines for safe and effective pediatric anti-obesity therapy. Full article

The primary objective of this research is to simplify and make the industrial manufacturing process of coated maraging steels more economical by combining the advantages of additive manufacturing with simultaneous bulk (aging) and surface (nitriding) treatment in an effective manner. With this aim, preliminary experiments were performed that demonstrated the hardness (and related microstructure) of an as-built MS1 maraging steel, produced by selective laser melting (SLM), is comparable to that of the bulk maraging steel products treated by conventional solution annealing. The direct aging of the solution-annealed and as-built 3D printed maraging steel resulted in similar hardness, indicating that the kinetics of the precipitation hardening process are identical for the steel in both conditions. This assumption was strengthened by a thermodynamic analysis of the kinetics and determination of the activation energy for precipitation hardening using Differential Scanning Calorimetry (DSC) measurements. Industrial target experiments were performed on duplex-coated SLM-printed MS1 steel specimens, which were simultaneously aged and salt-bath nitrided, followed by PVD coating with three different ceramic layers: DLC, CrN, and TiN. For reference, similar duplex-coated samples were used, featuring a bulk Böhler W720 maraging steel substrate that was solution annealed, precipitation hardened, and salt-bath nitrided in separate steps, following conventional procedures. The technological parameters (temperature and time) of the simultaneous nitriding and aging process were optimized by modeling the phase transformations of the entire heat treatment procedure using DSC measurements. A comparison was made based on the in-depth hardness profile estimated by the so-called expanding cavity model (ECM), demonstrating that the hardness of the surface layer of the coated composite material systems is determined solely by the type of the coatings and does not influenced by the type of the applied substrate materials (bulk or 3D printed) or its heat treatment (whether it is a conventional, multi-step treatment or a simultaneous nitriding + aging process). Based on the research work, a proposal is suggested for modernizing and improving the cost-effectiveness of producing aged, duplex-treated, wear-resistant ceramic-coated maraging steel. Full article

This study presents a strut-and-tie modeling (STM) framework for reinforced concrete (RC) deep beams strengthened with intraply hybrid composites (IRCs), integrating comprehensive experimental data from beams with three different span lengths (1.0 m, 1.5 m, and 2.0 m). Although the use of fiber-reinforced polymers (FRPs) for shear strengthening of RC members is well established, limited attention has been given to the development of STM formulations specifically adapted for hybrid composite systems. In this research, three distinct IRC configurations—Aramid–Carbon (AC), Glass–Aramid (GA), and Carbon–Glass (CG)—were applied as U-shaped jackets to RC beams without internal transverse reinforcement and tested under four-point bending. All experimental data were derived from the authors’ previous studies, ensuring methodological consistency and providing a robust empirical basis for model calibration. The proposed modified STM incorporates both the axial stiffness and effective strain capacity of IRCs into the tension tie formulation, while also accounting for the enhanced diagonal strut performance arising from composite confinement effects. Parametric evaluations were conducted to investigate the influence of the span-to-depth ratio (a/d), composite configuration, and failure mode on the internal force distribution and STM topology. Comparisons between the STM-predicted shear capacities and experimental results revealed excellent correlation, particularly for deep beams (a/d = 1.0), where IRCs substantially contributed to the shear transfer mechanism through active tensile engagement and confinement. To the best of the authors’ knowledge, this is the first study to formulate and validate a comprehensive STM specifically designed for RC deep beams strengthened with IRCs. The proposed approach provides a unified analytical framework for predicting shear strength and optimizing the design of composite-strengthened RC structures. Full article

Background: Bioelectrical Impedance Vector Analysis (BIVA) is a qualitative method that standardizes resistance and reactance relative to stature (R/H and Xc/H) and plots them as vectors on an R-Xc graph. This equation-free approach assesses body composition, allowing for the evaluation of hydration status and cellular integrity through tolerance ellipses. This study aimed to systematically map BIVA reference ellipses across general, pediatric, pathological, and athletic populations. Methods: A scoping review was conducted according to PRISMA-ScR guidelines. Five databases were searched. Extracted data included (a) sample characteristics (sample size, age, sex, BMI, country, ethnicity), (b) population type, (c) analyzer specifications, and (d) R/H and Xc/H means, standard deviations, and correlation values. Results: A total of 53 studies published between 1994 and July 2025 were included. From these, 508 tolerance ellipses were identified: 281 for the general population (18–92 years), 133 for children/adolescents (0–18 years), 49 for athletes, and 45 for pathological groups. Studies were primarily conducted in Europe and the Americas, using 11 analyzers with variations in measurement protocols, including body side, posture, and electrode placement. Conclusions: This scoping review categorizes the existing BIVA tolerance ellipses by population type, sex, age, BMI, device used, and measurement protocol. The structured presentation is intended to guide researchers, clinicians, nutritionists, and sports professionals in selecting appropriate reference ellipses tailored to specific populations and contexts. Full article

Fiber-reinforced composites (FRCs) are increasingly utilized in computer-aided design/computer-aided Manufacturing (CAD/CAM) workflows for both definitive and provisional restorations. Veneering these materials is essential not only for achieving aesthetic outcomes, but also to prevent direct exposure of oral tissues to glass fibers. This study evaluated the short- and long-term shear bond strength (SBS) between a veneering composite and FRC (Trinia, Bicon) with varying bonding interface orientations and load directions. Specimens were sectioned into discs with 1.5° or 45° tilt with respect to material’s layering planes and veneered with a composite pin (Ceramage, Shofu Inc.). SBS was tested after 24 h and 180 days of water storage, with forces applied either parallel or perpendicular to the layer orientation seen at the bonding interface. Long-term water storage significantly reduced SBS (24 h: 23.9 MPa vs. 180 d: 18.1 MPa, p < 0.001). In contrast, neither cutting direction (1.5° vs. 45°, p = 0.584) nor loading direction (parallel vs. perpendicular, p = 0.367) significantly influenced SBS. These results suggest veneering of the tested FRC material is clinically viable regardless of interface orientation or load direction. Although aging significantly reduced SBS, this was not clinically relevant, indicating that appropriate adhesive protocols may ensure durable bonding. Full article

Background: Jones fractures of the 5th metatarsal are frequently associated with nonunion due to limited vascularization and repetitive mechanical stress. The aim of the study was to compare the biomechanical performance of T-plate and bicortical screw fixation using standardized 3D models. Methods: Three-dimensional models of the 5th metatarsal were generated from CT images and printed using PolyJet technology (Stratasys J5 DentaJet) using a rigid-elastic composite with properties similar to cortical and cancellous bone. Jones fractures were fixed with either a locked T-plate or a bicortical screw. The samples were tested under axial and oblique static loads (α = 0°, 90°, 180°) and for three values of interfragmentary distance (d = 0.1–1 mm), in a 3 × 2 factorial design. Results: The T-plate fixation recorded a maximum yield force (Fmax) of 149.78 ± 8.53 N (138–161 N), significantly higher compared to the bicortical screw −98.56 ± 2.58 N (96–101 N), (p < 0.05). The ductility index was higher for the plate, indicating a progressive transition to yield. The α and d factors significantly influenced the mechanical behavior, with the polynomial model explaining over 95% of the total variation. Discussion: The plate fixation demonstrated greater strength and superior biomechanical tolerance in imperfect reduction scenarios. The main limitation is the lack of fatigue testing and the inability of 3D models to reproduce the structural heterogeneity of human bone. Conclusions: Implant selection should be individualized based on fracture stability. 3D models provide a reproducible platform for comparative evaluation of osteosynthesis methods, but future studies should include cyclic loading and biological validation. Full article

The network architecture has demonstrated considerable potential for enhancing the strength–ductility synergy in metal matrix composites (MMCs). Intuitively, the intersections of network layers are expected to induce a stress concentration, leading to premature brittle fractures. Introducing chamfers to round the network cells may mitigate the local stress concentration and thereby improve elongation. Here, a numerical simulation framework was developed to investigate the effect of chamfering on the mechanical behavior of a three-dimensional (3D) continuous SiC_3D/Al composite with a network architecture. A Voronoi tessellation algorithm was employed to generate the continuous network structural SiC phase. By inducing ductile and brittle damage criterions in the matrix and reinforcement elements, respectively, the mechanical behavior can be predicted via the finite element method (FEM). The predicted mechanical properties reveal an unexpected trend: chamfering results in a simultaneous reduction in both strength (from 367 MPa to 312 MPa) and elongation (from 4.1% to 2.0%). With chamfering, the enlarged intersection of the network layer bears a lower load, whereas the narrower network plates exhibit higher stress concentrations. As a result, the overall load-bearing capacity of the SiC_3D reinforcement decreases monotonically with an increasing chamfer size f. Furthermore, the non-uniform stress distribution promotes the premature fracture of the SiC_3D, which reduces elongation. Additionally, the crack deflection behavior is suppressed in the chamfered models, leading to decreasing energy dissipation. This unanticipated outcome highlights an important architectural design principle: maintaining uniform geometric dimensions is critical for achieving optimal composite performance. Full article

This paper presents a comprehensive analysis of the thermal stability and decomposition mechanisms of IPN hydrogels based on polyvinyl alcohol (PVA) and a copolymer network of poly(ethylene glycol) diacrylate–poly(ethylene glycol) methacrylate (PEGDA–PEGMA). Using thermogravimetric analysis (TGA/DTG) and multi-approach kinetic analysis (Friedman and Ozawa–Flynn–Wall isoconversion methods, nonparametric kinetics, Shestaka-Berggren model), the influence of composition on the processes of dehydration, thermal destruction, and the distribution of activation energy by degrees of conversion was investigated. The constructed three-dimensional kinetic “landscapes” made it possible to identify characteristic features of the behavior of various samples, including differences in the rate and mechanisms of destruction. It was found that an increase in the content of PVA enhances moisture binding and shifts the T_max of dehydration to higher temperatures, while an increase in the concentration of PEGDA forms a denser network that limits moisture retention and accelerates thermal decomposition. Calculation of diffusion coefficients using the Fick model showed a decrease in D with an increase in network density, which reflects an increase in resistance to moisture mass transfer. The combination of the data obtained demonstrates the multistage nature of thermal destruction and allows for the targeted selection of hydrogel compositions for biomedical, environmental, and materials science applications, including drug delivery systems, sorbents and heat-resistant coatings. Full article