Search Results (4,500)

Biodegradable metals represent a paradigm shift in orthopedic fixation by providing temporary mechanical support synchronized with bone healing while eliminating long-term complications associated with permanent implants. Conventional bioinert alloys, including stainless steels, Ti-based alloys, and Co-Cr alloys, exhibit high elastic moduli that induce stress shielding and often require secondary removal surgeries. In response, resorbable metallic systems based on Mg, Zn, and Fe have emerged as promising alternatives. Among these, Fe-Mn-C alloys stand out for load-bearing applications due to their exceptional strength-ductility balance governed by twinning-induced plasticity mechanisms, tunable degradation behavior, and intrinsic magnetic resonance imaging compatibility through austenitic phase stabilization. Focusing on Fe-Mn-C alloys, this review critically examines the metallurgical design principles underlying stacking fault energy optimization, phase stability, and Mn-controlled electrochemical behavior. Processing innovations, such as additive manufacturing, are discussed as tools to architecture porosity, refine microstructure, and accelerate degradation by graded designs while preserving mechanical structural support during healing. Hybrid metallic-bioactive systems, surface functionalization strategies, and functionally graded porous architectures were evaluated as advanced approaches to enhance osteointegration and modulate degradability. Despite these advances, significant barriers remain for clinical translation. Persistent discrepancies between in vitro and in vivo degradation rates, often attributed to biological encapsulation and degradation product accumulation, complicate lifetime prediction. Localized corrosion at microstructural heterogeneities such as twin boundaries and phase interfaces can undermine structural reliability under load-bearing conditions. Moreover, predictive multi-physics modeling frameworks capable of coupling electrochemical kinetics, mechanical loading, microstructural evolution, and bone remodeling remain underdeveloped, limiting reliable safety-margin estimation. Regulatory progress is further hindered by the absence of standardized testing protocols specifically tailored to Fe-based biodegradable alloys, including harmonized degradation rate windows, validated corrosion-mechanics coupling methodologies, and clinically defined Mn ion release thresholds. This review aims to discuss whether Fe-based alloys, especially Fe-Mn-C alloys, can transition from promising laboratory materials to clinically viable next-generation orthopedic implants capable of delivering patient-specific, mechanically compatible, and biologically synchronized temporary fixation. Full article

In this study, electrospun poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) biopapers were produced by annealing electrospun fiber mats from two commercial grades (151C and X131A) and compared with films prepared by the conventional melt-mixing/compression molding method. To obtain continuous biopapers, the fiber mats were subjected to mild thermal post-processing at various temperatures. The selected annealing temperatures were 140 °C (151C) and 130 °C (X131A), where interfiber coalescence occurred within a short annealing time (10 s), yielding continuous fibrous films (biopapers). To elucidate the structural mechanisms underlying interfiber coalescence, time-resolved synchrotron SAXS/WAXS and temperature-dependent FTIR spectroscopy were performed. These analyses showed that coalescence occurred through an interplay between thermally induced local ordering at sub-melting temperatures and premelting/partial melting of thin, ill-defined lamellae, with grade-dependent contributions. The resulting biopapers were evaluated against compression-molded films for optical, mechanical, and barrier properties relevant to packaging. All samples showed similar transparency, although compression-molded films were slightly more opaque. The lower-rigidity grade (151C) exhibited more ductile and tougher behavior than X131A. Biopapers showed slightly lower water and oxygen barrier performance than compression-molded films, attributed to differences in material compactness. Overall, brief mild annealing after electrospinning enabled continuous PHBH biopapers with balanced properties, supporting their potential for sustainable PHBH-based food-packaging applications. Full article

Background and Objectives: Pelvic fixation during robotic-assisted gait training (RAGT) may limit trunk–pelvis movement and influence functional recovery after stroke. This study investigated whether allowing pelvic motion during RAGT improves balance and gait performance in individuals with chronic stroke. Materials and Methods: A single-blind randomized controlled trial was conducted in 49 individuals with chronic stroke (PFG, n = 24; PRG, n = 25). Participants received Lokomat-assisted gait training (30 min/session, 3 sessions/week for 4 weeks) in addition to conventional therapy. The primary outcome was balance (BBS), and secondary outcomes included DGI, 10 MWT, and pelvic kinematics. Group × time interactions were analyzed using two-way repeated-measures ANOVA. Results: Significant group × time interactions were observed for BBS and DGI (p < 0.001), indicating greater improvements in the PRG. Gait speed improved significantly over time in both groups (p < 0.001), with no significant interaction for the 10 MWT. No significant interaction effects were found for pelvic kinematics, although a group main effect was observed for pelvic tilt. No adverse events were reported. Conclusions: Allowing pelvic motion during RAGT was associated with greater improvements in balance and dynamic gait performance compared with pelvic fixation. However, no corresponding changes were observed in pelvic kinematics, suggesting that functional improvements may not be explained by kinematic changes alone. Full article

The construction sector contributes approximately 40% of global energy-related CO₂ emissions, necessitating the development of low-carbon and high-performance sustainable building materials. The lightweight volcanic glass known as expanded perlite is an excellent candidate due to its pozzolanic reactivity, thermal insulation, and self-compacting properties. The literature review presented here is based on 100 articles (1985–2024) and examines the mechanical, thermal, durability, and sustainability aspects of this material. According to the literature, the incorporation of expanded perlite significantly reduces thermal conductivity, from 1.81 W/m·K in conventional concrete to 0.69 W/m·K and further to 0.034–0.06 W/m·K in insulation-oriented mixes. In addition, ground perlite exhibits enhanced pozzolanic reactivity, yielding up to 50% higher compressive strength at a 35% replacement rate. When added to self-consolidating concrete, perlite at 220–260 kg/m³ makes mixes more durable by reducing permeability, carbonation, and chloride-ion migration. However, higher perlite replacement levels adversely affect mechanical performance, with early-age compressive strength decreasing by more than 60% when cement replacement exceeds 30%. The appropriate percentage of perlite depends on the desired outcome. A content of 20% is ideal for balancing strength and durability, while higher levels up to 50% improve insulation and reduce density (25–400 kg/m³). Overall, expanded perlite demonstrates strong potential to enhance durability, reduce permeability, and improve sulfate resistance, positioning it as a viable material for low-carbon construction systems. Full article

Background: Despite mechanical hygiene, plaque-related illnesses like gingivitis and periodontitis affect over 3.5 billion people globally. Natural mouthwashes are becoming increasingly popular as consumers shift toward plant-based alternatives to chlorhexidine, which may have drawbacks that limit long-term acceptability. This study aimed to evaluate the short-term clinical potential of three herbal mouthwashes—Matricaria chamomilla (chamomile), Salvia officinalis (sage), and Zingiber officinale (ginger)—in reducing dental plaque and clinical signs of gingival inflammation in young adults. (2) Materials and Methods. A randomised controlled clinical trial was conducted on 175 systemically healthy participants, allocated equally into five groups (three herbal groups, placebo, and chlorhexidine). Each herbal group used a 2% aqueous infusion three times daily for twelve weeks. The 2% aqueous infusion concentration was selected based on commonly reported concentrations in previous phytotherapeutic and clinical studies evaluating herbal mouthwashes, balancing potential efficacy with safety and tolerability. The plant materials were sourced from certified suppliers, and standardized dried plant parts were used under controlled preparation conditions. Clinical assessments were performed at baseline (T0), week 1 (T1), week 5 (T2), and week 9 (T3), corresponding to the beginning of each evaluation interval within the 12-week study, using the Silness–Löe Plaque Index and the modified Löe–Silness Gingival Index. Data were analyzed using repeated-measures ANOVA with Bonferroni post hoc correction. (3) Results. Repeated-measures ANOVA revealed a significant main effect of time for both plaque accumulation and gingival index scores. For the Silness–Löe Plaque Index, a marked time-dependent reduction was observed across the active treatment groups (p < 0.001; η²_p = 0.56), with a significant time × group interaction (p < 0.001; η²_p = 0.49). Similarly, the modified Löe–Silness Gingival Index showed a significant reduction over time (p < 0.001; η²_p = 0.22), with a significant interaction effect between time and mouthwash type (p < 0.001; η²_p = 0.17). No statistically significant differences were found among the three herbal mouthwashes in post hoc Bonferroni comparisons (all p > 0.05), whereas all active treatments showed significantly better outcomes compared with the placebo. (4) Discussion. All three rinses showed similar clinical effects on plaque and gingival scores. However, without mechanistic assays, no claims can be made about comparable antibacterial or anti-inflammatory activity. Compared with conventional antiseptics such as chlorhexidine, herbal rinses offer important advantages in terms of biocompatibility, safety, and tolerability, with no staining, taste alteration, or mucosal irritation reported. At T3, the correlation between plaque and gingival indices was weak (Spearman’s ρ = 0.18, p = 0.09), suggesting limited linear association; this finding should be interpreted cautiously, as the low end-range values and limited variability of both indices at this time point may have masked a true association. This exploratory observation raises, but does not confirm, the possibility that factors other than plaque reduction may contribute to gingival improvement. (5) Conclusions. Significant reductions in dental plaque and clinical signs of gingival inflammation were observed following regular use of chamomile, sage, and ginger mouthwashes for twelve weeks. All herbal formulations exhibit similar clinical results. Longer-term controlled trials incorporating microbiological and phytochemical analyses are recommended to validate these findings further. Full article

The need to create lightweight materials with better mechanical properties has led to the use of Fiber Reinforced Composites (FRCs)s in the aerospace and automotive industries. The mechanical behavior of FRCs is heterogeneous, especially in conditions of low-velocity impact (LVI). The impact events cause structural damage, where most of the available literature deals with mono- or bi-composites in controlled situations. This work will present the results of studying the behavior of mono, bi- and tri-hybrids with carbon, glass and Kevlar fiber-reinforced epoxy. The sequences of the laminate stacks, number of plies and laminate thickness in the drop weight testing were across velocities of 1.91 to 3.91 m/s at drop heights of 19 to 79 cm. The dominant pillars of LVI, such as peak load, energy absorption and the modes of damage, were analyzed. The glass-dominated laminates peaked at 5.67 kN, while the Kevlar-dominated laminates reached peak flow in ductile collapse with greater quantities of absorbed energy. The leaders in strength and energy were the hybrids of Kevlar–glass (KG) cross-ply at 8.08 kN and 47.28 J and quasi-isotropic Kevlar–carbon–glass (KCG) at 9.12 kN and 47.25 J, showcasing a balance of strength and toughness. The rest, holding a greater quantity of Kevlar, ranging in thickness and cross-plies, were shaped with a load center. The experimental conclusion is that hybridization improved impact resistance and ductility, which is best supported by the glass/carbon rigidity-layered laminates. Such understanding directs the design work of future composite materials for better impact control. Full article

This work investigated the potential of different natural fillers, i.e., clay, calcium carbonate, and silica, as sustainable alternatives to glass fibers (GFs) in polyamide 6 (PA6) for Large-Format Additive Manufacturing (LFAM) applications in order to guarantee the chemical recyclability of the produced materials. Specifically, PA6-based composites containing ≤ 10 wt% natural fillers were compared with a conventional system (30 wt% GF-reinforced PA6) from rheological, morphological and thermo-mechanical perspectives. Rheological analysis showed that silica- and clay-filled samples displayed similar rheological response to the GF-filled reference due to their large particle size. Thermal analyses revealed a slight increase in crystallinity (up to 32%) for filled samples, indicating a potential nucleating effect of the natural fillers. Calcium carbonate-filled composites achieved thermal conductivity values comparable to the GF-filled reference (≥0.42 W/mK) indicating a high heat dissipation capability during printing operations. Morphological analysis performed on preliminary LFAM components revealed satisfactory printing quality and good filler dispersion. Flexural tests showed that silica and calcium carbonate could provide a balanced mechanical response, thereby reducing the anisotropy of printed components. These results demonstrated that the addition of suitable natural fillers at limited concentrations (≤10 wt%) can represent a lightweight and eco-sustainable alternative to GF reinforcement in LFAM applications. Full article

Purpose: To investigate the association between COVID-19 infection and the 1-year risk of acute urinary retention (AUR) and related urological complications in patients with benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTs). Materials and Methods: Using the TriNetX global network, patients with BPH and LUTs between January 2020 and January 2024 were identified. Participants were classified into a COVID-19 cohort (N = 32,948) and a non-COVID control cohort (N = 434,123). Propensity score matching (1:1) balanced demographics, comorbidities, medications, and laboratory parameters. The primary outcome was AUR within one year. Secondary outcomes included Foley catheterization, urinary tract infection (UTI), gross hematuria, bladder stones, and prostate-related surgery. Results: After matching, 32,918 patients remained in each cohort. The COVID-19 group showed a significantly higher 1-year incidence of AUR compared with controls (2.18% vs. 0.32%; aHR 6.89, 95% CI 5.62–8.45; p < 0.0001). Increased risks were also observed for Foley catheterization (aHR 4.10), UTI (aHR 3.52), and prostate-related surgery (aHR 6.02). Kaplan–Meier analysis demonstrated persistent divergence in AUR-free survival. Conclusion: COVID-19 infection is independently associated with a markedly increased risk of AUR and urological complications in patients with BPH, highlighting the need for closer post-infection monitoring. Full article

The focus of this work was to investigate the mechanical properties of additively manufactured (AM) discontinuous carbon fibre-reinforced polymer (DCFRP) composites. Towards the specimen’s fabrication, the Fused Filament Fabrication (FFF) additive manufacturing technique was employed. A number of input printing parameters were varied, such as the infill pattern, infill density, layer height, shell configuration, and raster orientation, in a systematic way. The role of these paraments on the mechanical properties, such as tensile, flexural, and impact strength were investigated. The data was analysed in-depth and the “main effect method” was employed for their comparative ranking. The results of this study showed that tensile and bending strengths were strongly correlated with material content and structural reinforcement. The specimens attained up to 76.7 MPa of tensile strength, while the flexural strength was up to 159.4 MPa, with a deflection of up to 8 mm and 16 mm, respectively. Solid infills, higher densities, finer layer heights, and added shells significantly improved the strength and stiffness. Grid-patterned and low-density specimens caused poor load-bearing capacities, while hexagonal and gyroid infills offered a more balanced performance. Full article

Peripheral nerve injuries involving critical-sized gaps remain a major clinical challenge. Although autologous nerve grafting is considered the gold standard for peripheral nerve repair, its clinical application is limited by the availability of donor nerve tissue and the risk of donor-site morbidity, including sensory deficits and functional impairment. Therefore, nerve guidance conduits (NGCs) have emerged as a promising alternative when combined with bioactive modulation strategies. In this study, we evaluated bisvinyl sulfonemethyl (BVSM)-crosslinked gelatin conduits integrated with electrical stimulation (ES) at different frequencies (0, 2, 20, and 200 Hz) in a rat sciatic nerve defect model over a 4-week recovery period (n = 10 per group). Structural regeneration was assessed by morphometric analysis, electrophysiology, macrophage infiltration, CGRP immunoreactivity, retrograde Fluorogold tracing, quantitative PCR of growth factors and inflammatory cytokines, and behavioral testing. Among all stimulation paradigms, low-frequency ES at 2 Hz produced the most pronounced regenerative effects. The 2 Hz group demonstrated significantly greater axon number, axonal density, and regenerated nerve area compared with control and high-frequency groups (p < 0.05). Electrophysiological assessments revealed improved nerve conduction velocity, higher MAP amplitudes, and shorter latencies. Enhanced macrophage recruitment and elevated CGRP expression were observed, suggesting coordinated neuroimmune and neurochemical activation. Gene expression analysis indicated upregulation of neurotrophic factors and balanced inflammatory cytokine responses under low-frequency stimulation. In contrast, high-frequency stimulation (200 Hz) failed to enhance overall regeneration and showed reduced axonal metrics, suggesting possible overstimulation-associated suppression. Collectively, these findings demonstrate that BVSM-crosslinked conduits provide a stable and biocompatible regenerative scaffold, and that appropriately tuned low-frequency electrical stimulation (2 Hz) optimally enhances structural, molecular, and functional recovery. The integration of material engineering with bioelectrical modulation represents a promising strategy for next-generation bioelectronic interfaces in peripheral nerve repair. Full article

The rapid expansion of wireless communication in urban environments requires antenna systems that balance high electromagnetic performance with stringent aesthetic and security constraints. This review examines recent advances in concealed antenna technologies integrated into building structures, with a focus on performance variation, material-induced attenuation, and emerging concealment strategies. Techniques such as transparent conductors on glass, structural embedding within walls, and camouflage-based designs are shown to significantly influence resonance behavior, radiation efficiency, and pattern characteristics compared to free-space operation. Despite these challenges, optimized solutions including transparent conductive oxide arrays, wideband embedded antenna geometries, and metasurface-enhanced window structures can partially recover performance while maintaining optical transparency above 70%. Material loading effects are found to induce resonant frequency shifts of approximately 10–44%, depending on dielectric properties and environmental conditions. Transparent antenna arrays achieve gains ranging from 0.34 to 13.2 dBi, while signal-transmissive wall systems demonstrate transmission improvements of up to 22 dB relative to untreated building materials. These technologies enable a wide range of applications, including 5G and beyond-5G cellular networks across sub-6 GHz and millimeter-wave bands, as well as Internet of Things systems and smart city infrastructure. However, key challenges remain, including the need for comprehensive characterization of building material electromagnetic properties, optimization of multilayer structural environments, and the development of standardized design and evaluation methodologies. This review provides a unified framework for understanding the tradeoffs associated with antenna concealment and identifies critical research directions for the development of building-integrated wireless systems in next-generation communication networks. Full article

Fibroin-based films represent a promising platform for sustainable and bio-derived materials. Existing literature has mainly focused on isolated molecules, plasticizers, or chemical cross-linkers, and the function of complex, multi-component natural extracts as structure-modulating agents in fibroin films remains poorly understood. In this study, edible films containing mulberry leaf extract (MLE; 2–8 wt%) and fibroin (8 wt%) were prepared by solution casting, and their structures were investigated using spectroscopic, morphological, thermal, mechanical, and barrier property analyses. The results reveal that MLE induces concentration-dependent changes in film performance through multicomponent, non-covalent interactions with the fibroin. An approximately 187% increase in tensile strength was achieved at high MLE concentration, confirming effective physical reinforcement. The water vapor transmission rate decreased markedly from 0.888 to 0.170 g·h⁻¹·m⁻², indicating an enhanced moisture barrier, whereas oxygen permeability increased at higher extract loadings, suggesting localized chain rearrangements. High optical transparency in the visible region was maintained (79.95–83.77%), while UV response was selectively altered with extract concentration. Overall, the 8MLE formulation exhibited the most balanced performance. This study demonstrates that plant-derived extracts can serve as effective natural modifiers for tailoring fibroin film properties without inducing crystallization, offering a sustainable strategy for designing bio-based and edible protein film systems. Full article

This review comprehensively examines the incorporation of nanoparticles (NPs) into biopolymers for 3D printing in biomedical applications, integrating material design, processing strategies, and translational considerations within a unified framework. Different types of NPs are analyzed regarding their effects on mechanical reinforcement, rheological modulation, and structural organization of biopolymeric matrices. The discussion covers principal additive manufacturing technologies, including extrusion-based systems such as fused deposition modeling (FDM) and direct ink writing (DIW), vat photopolymerization, powder-bed fusion (SLS), and emerging in situ nanoparticle formation approaches, emphasizing how nanoparticle loading and surface functionalization govern yield stress, shear-thinning behavior, viscoelastic recovery, and dimensional fidelity while mitigating agglomeration and optimizing interfacial interactions. Comparative evaluation of compressive modulus, strength, toughness, crystallinity, and porosity establishes structure–property–processing relationships directly linked to printability and functional performance. Biomedical applications are addressed in tissue engineering, biosensing, controlled and targeted drug delivery, and bioimaging, highlighting the balance between bioactivity and manufacturability. Finally, critical challenges—including compatibility, reproducibility, biological safety, long-term stability, regulatory adaptation, and environmental impact—are discussed, alongside future perspectives focused on green nanomaterials, AI-driven predictive formulation design, and digital twins for real-time monitoring and quality control in nano-enabled additive manufacturing. Full article

Children’s scooters, as products integrating mobility, safety, and developmental functions, require systematic and reliable design decision-making approaches. However, existing processes often suffer from unsystematic user demand extraction, strong subjectivity in weight determination, and insufficient quantitative support for evaluating alternative schemes. To address these issues, this study proposes an integrated AHP–CRITIC–VIKOR framework for engineering-oriented design optimization. User requirements are identified through field investigation, questionnaires, and affinity diagram analysis, and a multi-level evaluation indicator system is constructed. AHP is applied to determine subjective weights, while CRITIC incorporates objective data characteristics, enabling balanced weighting. VIKOR is then used to evaluate design schemes and obtain compromise solutions under multi-criteria conflicts. The results show that safety-related factors, including material safety, braking performance, and load-bearing capacity, dominate the decision process. The optimal scheme demonstrates the closest proximity to the ideal solution. Sensitivity analysis confirms the robustness of the model, and comparison with TOPSIS shows consistent results and improved compromise decision capability. The proposed framework enhances decision reliability and provides an effective quantitative tool for multi-criteria product design optimization. Full article

This study investigates the influence of waste-based materials, namely drinking water treatment sludge (DWTS) and expanded glass production waste (EGPW), on the properties of fine-grained concrete when used as partial Portland cement replacements. Fine-grained concrete mixtures containing different proportions of DWTS and EGPW were evaluated in terms of hydration behavior, microstructural development, mechanical performance, durability, and dimensional stability. Density, ultrasonic pulse velocity, water absorption, flexural and compressive strengths, drying shrinkage, and porosity parameters were determined, while frost resistance was assessed and predicted based on porosity characteristics. Hydration kinetics were analyzed using X-ray diffraction and semi-adiabatic calorimetry. The results showed that increasing EGPW content enhanced cement hydration processes and promoted matrix densification through pozzolanic reactions, resulting in reduced water absorption and improved mechanical properties. In contrast, DWTS exhibited an inhibiting effect on hydration due to its inert nature and high Fe₂O₃ content, acting primarily as a micro-filler; however, when combined with EGPW at moderate dosages, DWTS contributed positively to flexural strength and slightly reduced drying shrinkage. The combined use of DWTS and EGPW enabled the formation of a balanced pore structure and improved the durability of fine-grained concrete. Among the tested mixtures, ED-3 (7.5% EGPW + 5% DWTS) provided the most favorable balance between hydration activation and binder reduction, while the highest frost resistance was achieved by the ED-4 mixture, reaching approximately 603 predicted freeze–thaw cycles. Overall, the results indicate that properly optimized combinations of EGPW and DWTS can significantly enhance the performance and durability of fine-grained concrete while controlling drying shrinkage. Full article