Search Results (1,997)

Additive manufacturing (AM) has evolved from a rapid prototyping technique into a versatile platform for fabricating advanced functional materials and complex engineering components. While polymers remain the dominant material class due to their processability and tunable properties, recent developments have expanded AM to include high-performance composites, nanocomposites, and metallic materials. This review provides an overview of functional materials for additive manufacturing, emphasizing the relationships between material design, processing conditions, microstructure evolution, and resulting properties. Key functional polymer systems are discussed, including conductive, stimuli-responsive, elastomeric, high-performance, bio-based, and nanocomposite materials reinforced with nanoparticles, carbon nanomaterials, MXenes, and fibers. This review also examines processing–structure–property relationships common to polymer- and metal-based AM, highlighting the roles of anisotropy, defect formation, residual stresses, and post-processing in determining component performance. Finally, current challenges and emerging trends—including multi-material and 4D printing, machine learning-assisted optimization, and digital materials design—are discussed. Overall, the review highlights how advances in materials science and intelligent manufacturing are expanding the capabilities of additive manufacturing for multifunctional engineering and biomedical applications. Full article

This study investigates the mechanical and thermal properties of epoxy composites reinforced with aluminum nanoparticles (Al NPs), titanium nanoparticles (Ti NPs), and chopped E-Glass fibers, individually and in hybrid combinations. Thirteen compositions were systematically fabricated and characterized, spanning pure epoxy (PRC0), Al NP-series (PRA1–3), Ti NP-series (PRT1–3), Al NP/E-Glass hybrid series (PRAG1–3), and Ti NP/E-Glass hybrid series (PRTG1–3). The investigation evaluates the effects of these reinforcements on tensile strength, flexural strength, Shore D hardness, thermogravimetric stability, and microstructure. The PRTG2 composite (2 wt% Ti NP + 2 wt% E-Glass fiber) achieved the highest tensile strength of 80 MPa (33.3% improvement over pure epoxy) and the highest flexural strength of 115 MPa (43.75% improvement). These results demonstrate the superior reinforcing efficiency of Ti nanoparticles over Al nanoparticles and the synergistic benefit of combining nanoparticle and fiber reinforcements within a single epoxy matrix. Full article

Carbon fibers, whose origins are closely intertwined with precursor chemistry and processing conditions, have become indispensable structural lightweight materials due to their exceptional combination of low density, high tensile strength, and high stiffness. This review aims to provide a combined overview of the mechanical properties of carbon fibers by tracing their development from the historically dominant polyacrylonitrile (PAN) and mesophase pitch systems to emerging polyethylene (PE)-based alternatives. Based on decades of fundamental and applied research, this review outlines how precursor molecular structure, stabilization pathways, and carbonization conditions direct microstructural growth and thereby mechanical performance. Established structure/property relationships in PAN and mesophase pitch fibers are discussed alongside recent insights into the sulfonation, crosslinking, and carbonization behavior of PE-based precursor systems. Additionally, this review presents current knowledge on production costs, market dynamics, and the environmental impact of carbon fiber manufacturing, highlighting how energy-intensive processing remains a key barrier to broader industrial adoption. Combined, the findings presented in this review provide an integrated basis describing how precursor selection, processing strategy, and resulting morphology shape mechanical behavior and clarify the position of PE-based carbon fibers within the broader landscape of cost, performance, and sustainability. Full article

This study develops a rapid-hardening and high-fluidity ultra-high-performance cement (UHPC)-based grout by incorporating calcium sulfoaluminate (CSA) cement as an early strength component, along with steel and wollastonite fibers as hybrid reinforcements. The UHPC grout proportions containing different contents of CSA cement and wollastonite fibers were designed to investigate fluidity, mechanical properties, hydration kinetics, microstructure and chloride resistance. The results showed that both CSA cement and wollastonite fibers significantly enhanced the compressive and flexural strength of UHPC grout. The incorporation of CSA cement led to rapid compressive strengths of 23 MPa at 6 h and 75.9 MPa at 1 day, marking a significant enhancement compared to the reference group and indicating excellent early-age performance. CSA cement accelerated the hydration process of the UHPC grout and promoted formation of more ettringite. Wollastonite fibers and U-type expansive agent (UEA) further improved the mechanical performance through bridging and physical filling effects. Moreover, CSA cement and wollastonite fibers effectively optimized expansion behavior and refined pore structure of the UHPC grout, and improved its chloride penetration resistance. Although both components influenced the fluidity of the grout, the UHPC grout still maintained high fluidity, offering a promising outlook for its potential use in demanding engineering applications. Full article

This study examines how yarn microstructure influences isothermal water-vapor transport and the associated evaporative heat loss under ISO 11092 skin-model conditions. Sweating guarded hotplate experiments were performed on PET yarn-array specimens to measure evaporative heat flux and moisture resistance. A fiber-level two-dimensional finite element model was then developed to reproduce the same boundary conditions and simulate transport through a PET fiber/air matrix. Using a full-factorial design, denier per filament, the number of filaments, and packing factor were varied independently, with multiple random filament arrangements used for each parameter combination to account for microstructural variability. The model reproduced the main experimental trends and gave predictions consistent with measured heat flux and moisture resistance for representative yarn configurations. Over the investigated design space, packing factor had the strongest influence: higher packing reduced heat and moisture flux and increased moisture resistance. Denier per filament and the number of filaments showed smaller but systematic effects, mainly through changes in pore connectivity and tortuosity. Statistical analysis indicated that main effects accounted for most response variation, while interaction effects were limited within the studied ranges. Flow-field results further showed a shift from internal flow penetration at low packing to bypass-dominated transport at high packing. These findings provide a validated framework for linking yarn-level structural parameters with heat–moisture transport performance in fibrous assemblies. Full article

Lunar regolith simulant (LRS) geopolymers are promising construction materials for lunar in situ resource utilization, but their brittle behavior and limited crack resistance restrict their structural applications. This study investigated the effect of basalt fiber length on the mechanical properties, failure modes, stress–strain behavior, constitutive relationship, and microstructure of CQU-1 LRS geopolymers. Basalt fiber-reinforced LRS geopolymers were prepared under weak alkali activation and high-temperature curing at 80 °C. The basalt fiber content was fixed at 0.1%, and six fiber lengths of 0, 6, 9, 12, 15, and 18 mm were considered. Compressive and flexural tests were conducted after curing for 1 d and 7 d, and the normalized stress–strain curves were fitted using the Saenz L.P., Carreira D.J., and Zhenhai Guo models. The results showed that basalt fiber length significantly affected the mechanical performance of LRS geopolymers. An appropriate fiber length improved strength, stiffness, ductility, and post-peak load-bearing capacity, whereas excessively short or long fibers weakened the reinforcing effect. The 15 mm fiber group exhibited the best overall performance. After curing for 1 d, its compressive strength reached 2.23 MPa, 49.7% higher than that of the control group, and its elastic modulus increased approximately 2.5-fold. After curing for 7 d, its compressive strength reached 13.44 MPa, 32.0% higher than that of the control group. The Zhenhai Guo model provided the best fit for the stress–strain curves. SEM-EDS analysis showed that basalt fibers improved interfacial bonding and promoted gel enrichment near the fiber–matrix interface. Overall, 15 mm was recommended as the optimal basalt fiber length for CQU-1 LRS geopolymers under the conditions used in this study. Full article

This study comprehensively investigates the thermal and mechanical degradation behavior of molded glass-fiber-reinforced plastic (GFRP) grating composites subjected to temperatures ranging from 80 °C to 320 °C. Three types of industrially produced GFRP gratings—open-type (OG), thin closed-skin (CG), and thick closed-skin (TCG)—were evaluated using mechanical, microstructural, chemical, and crystallographic analyses. Three-point bending tests revealed that TCG-type specimens exhibited superior thermal resistance, experiencing only a 43.9% loss in strength at 320 °C, whereas OG-type specimens showed significant resin degradation, fiber–matrix decomposition, and microcrack formation at temperatures above 200 °C. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) analyses revealed significant resin degradation, fiber–matrix decomposition, and microcrack formation. Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) confirmed substantial mass loss and structural disintegration at temperatures above 200 °C. Dynamic Mechanical Analysis (DMA) results revealed that the glass transition temperature (Tg) occurred at approximately 115–120 °C. The second-order regression model developed to estimate flexural strength under increasing temperature provided high accuracy (R² > 0.99) for all grating types. It should be noted that this investigation focuses on the short-term thermo-mechanical response under fundamental flexural loading to provide an accurate baseline for preliminary engineering design. The findings emphasize that the effect of temperature should be considered a critical parameter in the structural design of GFRP systems, especially in industrial environments with temperatures above 120 °C. Accordingly, tables for material selection and load-carrying capacity should be recalibrated to account for short-term temperature effects. Full article

Expansive soil is highly susceptible to water-softening and desiccation cracking under alternating wet–dry conditions, often resulting in severe geotechnical and geological hazards. To mitigate these undesirable engineering properties, a composite improvement approach utilizing biochar and sisal fiber was employed. The shear strength and cracking characteristics of the improved expansive soil were systematically investigated through direct shear tests and desiccation cracking tests on specimens prepared with varying biochar contents, sisal fiber contents, and fiber lengths. Scanning electron microscopy (SEM) was further conducted to elucidate the underlying microstructural mechanisms. The results indicated that the individual addition of biochar or sisal fiber enhanced the shear strength of the expansive soil. Increasing the biochar content from 4% to 10% yielded an 8–19% strength gain, whereas raising the sisal fiber content from 1.5‰ to 6‰ led to a more substantial 36–110% improvement. Conversely, extending the fiber length from 10 mm to 30 mm diminished the shear strength by 11–21%. Higher biochar contents progressively increased the internal friction angle (from 14.84° to 18.52°) but were accompanied by a decline in cohesion (from 9.0 kPa to 4.0 kPa). In contrast, increasing the sisal fiber content markedly enhanced cohesion (from 4.7 kPa to 50.3 kPa) while marginally reducing the internal friction angle (from 15.2° to 12.8°). In terms of crack suppression, a 10% biochar content achieved an 86.8% reduction in crack ratio, while 6‰ sisal fiber yielded a 72.4% reduction. Range analysis revealed that crack length and crack ratio were most sensitive to biochar content, whereas crack width was predominantly governed by fiber content. Notably, surface cracking was completely eliminated in the composite specimen prepared with 10% biochar, 4.5‰ sisal fiber, and a fiber length of 20 mm. Microstructural analysis revealed that biochar particles featured rough surfaces and abundant internal pores, while the sisal fibers formed a randomly interwoven network within the soil matrix. The synergistic interplay between the rigid biochar skeleton and the flexible fiber network contributed to the substantial enhancement in both mechanical strength and crack resistance. Full article

Background/Objectives: Subjective tinnitus, the underlying mechanism of which remains largely unknown, accounts for the majority of cases. Although conventional MRI and audiometric assessments demonstrate limited effectiveness in identifying organic causes, advanced microstructural techniques—such as diffusion tensor imaging (DTI) and fiber tractography—facilitate the evaluation of microanatomical connectivity related to auditory processing. This study employed DTI to examine alterations in microanatomical brain connectivity in patients with chronic subjective tinnitus, in comparison to a healthy control group. Methods: This study performed a comparative analysis of whole-brain connectivity maps, derived from Diffusion Tensor Imaging, between 47 patients with chronic subjective tinnitus (symptom duration ≥ 2 years) and 42 healthy controls. To ensure a robust assessment of micro-anatomical neural connectivity, DTI datasets were processed using the DSI Studio platform, with anatomical regions systematically mapped using automatic anatomical labeling atlases. Specifically, these metrics were evaluated across nodes in the central auditory pathway and limbic system to identify potential disruptions in structural integrity. Results: The comparative analysis revealed significant micro-anatomical connectivity alterations in patients with chronic subjective tinnitus. Changes in structural integrity were observed predominantly across key nodes within the central auditory pathway and limbic system, specifically involving the frontal, submarginal, cingular, insular, parietal, precuneus, cuneus, amygdala, thalamus, supplementary motor area, and precentral regions. Conclusions: Chronic subjective tinnitus was associated with a distinct, largely asymmetrical pattern of whole-brain structural connectivity, predominantly involving nodes of the salience, default-mode, and central-executive networks. Because behavioral, audiometric, and cognitive measures were not acquired, these findings are exploratory and hypothesis-generating; their cognitive and occupational relevance will require confirmation in studies that combine connectivity mapping with direct behavioral and audiological testing. Full article

Physical treatment can improve the quality and overall characteristics of insoluble dietary fiber (IDF). This study investigated the effects of microjet homogenization treatment (MT), ultra-high-pressure treatment (HP), and ultrasonic treatment (UT) on the compositional profile, microstructure, basic properties, and bioactivity of IDF from okara. The modification processes increased IDF yield (unmodified IDF: 65.55%; MT-IDF: 70.51%; HP-IDF: 75.29%; UT-IDF: 79.09%). The mechanical action disrupted the compact structure, refined the particles, and increased the specific surface area (SSA). Compared with unmodified IDF (0.18 m²/g), the SSA values of MT-IDF, HP-IDF and UT-IDF increased by 83.33%, 50.00%, and 72.22%, respectively, thereby improving the overall hydration characteristics and adsorption performance of IDF. UT-IDF exhibited excellent water-holding capacity (8.11 g/g), yet its thermal stability ((mass loss: unmodified IDF (36.50%), MT-IDF (23.59%), HP-IDF (26.11%), and UT-IDF (33.74%)) and rheological properties (shear rate range of 35–40 s⁻¹: unmodified IDF (1.77 Pa·s), MT-IDF (15.86 Pa·s), HP-IDF (21.11 Pa·s), UT-IDF (5.36 Pa·s)) were relatively inferior to those of MT-IDF and HP-IDF. Notably, MT-IDF exhibited superior modification effects, including a loose, porous microstructure, enhanced adsorption performance, and favorable prebiotic potential (Lactobacillus acidophilus 36h-OD₆₀₀: 0.594; Bifidobacterium longum 36h-OD₆₀₀: 0.509). Among the three physical modification methods, MT offers significant advantages in enhancing the quality of IDF from okara, improving its processing suitability, and facilitating its high-value utilization. However, this study still has certain limitations: the evaluation of the correlation between fiber digestion rate and probiotic potential was based only on in vitro models and has not been systematically evaluated using real food matrices. Full article

The escalating threat of antimicrobial resistance has spurred extensive research into antimicrobial fibers. While numerous reviews have comprehensively cataloged the classification and mechanisms of natural, inorganic, and organic antimicrobial agents, a critical gap remains: few have systematically evaluated the engineering strategies that translate intrinsic biocidal activity into durable, real-world fiber performance. This review addresses this gap by shifting focus from encyclopedic enumeration to a problem-oriented critical assessment of performance optimization strategies. We examine recent advances in natural fibers (bamboo, hemp, chitosan, jute) and synthetic fibers modified with antimicrobial agents, with emphasis on three core challenges—poor wash durability of natural agents, aggregation and leaching of inorganic nanoparticles (e.g., Ag, ZnO, MOFs), and structural limitations of organic agents (e.g., QACs, QPSs, N-halamines, PHMB). Key optimization routes, including covalent grafting, microstructural control (e.g., triaxial microfluidic spinning), organic-inorganic hybridization, and rechargeable N-halamine systems, are critically assessed for their effectiveness in enhancing washing resistance, stability, and antimicrobial synergy. Based on this comparative synthesis, we identify future directions—smart-responsive systems, sustainable processing pathways, and standardized evaluation protocols—to guide the rational design of next-generation high-performance antimicrobial fibers. Full article

In this study, composite nanofibrous membranes composed of poly(vinyl alcohol) (PVA), gelatin, and zein loaded with different contents of dihydromyricetin (DMY) were fabricated via electroblowing spinning (EBS). The effects of DMY content on the microstructure, physicochemical properties, mechanical strength, and functional performance of the membranes were evaluated. Scanning electron microscopy (SEM) analysis showed that the average fiber diameter increased from 174 ± 29 nm to 221 ± 35 nm with increasing DMY content, followed by a slight decrease at higher loading levels, indicating that DMY incorporation influences fiber morphology. Fourier transform infrared spectroscopy (FTIR) results suggested the presence of hydrogen bonding interactions between DMY and the polymer matrix. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) results indicated changes in the physical state of DMY within the nanofibrous system as the loading content increased. All samples exhibited a typical two-stage release behavior, and the highest cumulative release (nearly 55%) was observed at a DMY loading of 22.5%, while further increasing the loading reduced the release efficiency to approximately 45%. The release profiles were well described by a first-order kinetic model. The composite membranes exhibited improved surface hydrophilicity, appropriate water vapor permeability, antioxidant activity, and antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). This study demonstrates the successful fabrication of DMY-loaded PVA/gelatin/zein nanofibrous membranes and provides preliminary insights into their structure–property–function relationships, release behavior, antioxidant activity, and antibacterial activity against representative bacteria, although further application-oriented validation is still required. Full article

The mechanical behavior of bamboo scrimber dowel-bearing under sustained loading was investigated via the Stepped Isothermal Creep Deformation (SICD) method using a 30-ton multi-field coupling system, with the test conducted over a duration of 51.5 h. Experimental results revealed three typical failure modes: material failure, local compression failure, and crushing failure. The damage degree increased linearly with stress level. SEM microstructural analysis further indicated that failure originated from progressive fracture and bending of fiber bundles, as well as layer compression and cracking induced by mechanical loading. The deformation process of bamboo scrimber dowel-bearing under sustained loading comprises four distinct stages, namely short-term deformation, initial creep, stable creep, and divergent creep. The divergent creep stage manifests exclusively at stress levels of S_L = 0.6, while at lower-stress levels, S_L = 0.2 and S_L = 0.4, only the first three stages are observed within the 51.5 h test duration. In addition, a preliminary analysis was conducted on the stiffness and strength reduction in bamboo scrimber dowel-bearing under sustained loading. These research findings elucidate the mechanical behavior of bamboo scrimber dowel-bearing under sustained loading, providing preliminary insights to inform future durability assessment and design methodology development for bamboo scrimber joint connections. Full article

This study compared the effects of air freezing (AF), immersion freezing (IF), and ultrasound-assisted immersion freezing (UIF) at different power levels on the physicochemical properties, oxidative characteristics, and the structural and functional properties of myofibrillar protein (MP) of fresh beef. The results showed that UIF treatments generally outperformed AF and IF, with UIF-400 W exhibiting the best performance in maintaining beef quality. Specifically, UIF-400 W mitigated muscle fiber damage by inhibiting ice crystal growth, significantly improved water-holding capacity and color stability, reduced shear force, and effectively delayed protein and lipid oxidation. In addition, UIF-400 W brought the rheological properties, emulsifying properties, water distribution, and gel microstructure of MP closer to those of fresh beef. These findings highlight that UIF-400 W can effectively preserve beef quality as well as the structural and functional characteristics of MP, reduce oxidative damage, and thus become a promising technology for quality improvement of beef during freezing. Full article

This study investigates the thermo-mechanical and microstructural performance of concrete incorporating waste tire rubber (WR) and recycled steel fibers (WS) under elevated temperatures. Four mixtures were prepared: plain concrete (PL), rubber-modified concrete (WR5), and hybrid mixtures containing 0.4% and 0.8% steel fibers (WS0.4WR5 and WS0.8WR5). Specimens were exposed to temperatures of 400 °C, 600 °C, and 800 °C to simulate fire conditions. The results indicate that the incorporation of rubber reduces compressive strength at ambient temperature due to its lower stiffness and weak interfacial bonding. However, the addition of recycled steel fibers significantly improves crack resistance and enhances thermal stability. At 400 °C, the WS0.8WR5 mixture showed a retention rate of 92.9% (absolute strength: 44.32 MPa), compared to 72.2% for plain concrete (absolute strength: 44.11 MPa). Although the hybrid mixture has a lower ambient strength (47.68 MPa vs. 61.07 MPa), its superior retention makes it competitive in fire scenarios. Ultrasonic pulse velocity (UPV) measurements revealed a strong correlation with compressive strength degradation, confirming its effectiveness as a non-destructive indicator of internal damage. Microstructural analyses (SEM, XRD, and TGA-DTA) demonstrated that elevated temperatures lead to dehydration, phase transformation, and increased porosity, while steel fibers help maintain matrix integrity through crack-bridging mechanisms. The findings highlight a synergistic interaction between waste rubber and steel fibers, offering a sustainable and effective approach for improving the fire resistance of concrete. Full article