Search Results (1,282)

Given that the stock of coal gangue is increasing annually, and especially considering the problem of resource utilization after the spontaneous combustion of coal gangue accumulations with large thickness, the post-spontaneous combustion of coal gangue (SC coal gangue) from Yangquan, Shanxi, was selected as a research object. After crushing and screening, SC coal gangue was used as a coarse and fine aggregate, and through concrete mix design and a trial mix of concrete and mix ratio adjustment, concrete of strength grade C20 was obtained. Through experiments, the strength, elastic modulus, frost resistance, carbonation depth and other performance indicators of the concrete were measured. Using the SC coal gangue concrete, a 20 mm thick SC coal gangue panel was designed and manufactured. Through experimental tests, the bearing capacity, hanging force, impact resistance, impermeability and other properties of the board met the requirements of the relevant standards for building wallboard. For the SC coal gangue panel composite rock wool, its heat transfer coefficient decreased by 34.0%, air sound insulation was $\ge 45 \mathrm{d}\mathrm{B}$, and the self-weight of the external wallboard was reduced by 37.5%, so the related performance was better than the requirements of the current standard. The research results have been successfully applied to an office building project in Shanxi, China. Using SC coal gangue to make the external wallboard of the building, the reduction and recycling of solid waste are realized. In addition, the production of wall panels has been industrialized, thereby improving the construction efficiency. Full article

This study examines the influence of steel fiber reinforcement on the mechanical properties of geopolymer concrete incorporating different slag to fly ash binder ratios (75:25, 50:50, and 25:75). Three fiber contents (0%, 1%, and 2%) by volume were used to assess their impact on compressive strength, flexural strength, initial stiffness, and toughness. Compressive tests were conducted at 1, 7, and 28 days, while flexural behavior was evaluated through a four-point bending test at 28 days. The results showed that geopolymer concrete with 75% slag and 25% fly ash experienced the highest compressive strength and modulus of elasticity, regardless of the steel fiber content. The addition of 1% and 2% steel fiber content enhanced the compressive strength by 17.49% and 28.8%, respectively, compared to the control sample. The binder composition of geopolymer concrete plays a crucial role in determining its compressive strength. Reducing the slag content from 75% to 50% and then to 25% resulted in a 15.1% and 33% decrease in compressive strength, respectively. The load–displacement curves of the 2% fiber-reinforced beams display strain-hardening behavior. On the other hand, after the initial crack, a constant increase in load causes the specimen to experience progressive strain until it reaches its maximum load capacity. When the peak load is attained, the curve gradually drops due to a loss in load-carrying capacity known as post-peak softening. This behavior is attributed to steel’s ductility and is evident in specimens 75S25FA2 and 50S50FA2. Concrete with 75% slag and 25% fly ash demonstrated the highest peak load but the lowest ultimate displacement, indicating high strength but brittle behavior. In contrast, concrete with 75% fly ash and 25% slag showed the lowest peak load but the highest displacement. Across all binder ratios, the addition of steel fibers enhanced the flexural strength, initial stiffness, and toughness. This is attributed to the bridging action of steel fibers in concrete. Additionally, steel fiber-reinforced beams exhibited a ductile failure mode, characterized by multiple fine cracks throughout the midspan, whereas the control beams displayed a single vertical crack in the midspan, indicating a brittle failure mode. Full article

Growing concerns over the toxicity and sustainability of dental materials have driven the search for alternatives to bisphenol A-glycidyl methacrylate (Bis-GMA), a widely used dental resin monomer associated with health risks. This study highlights the potential of less health-hazardous dental formulations by incorporating high-value materials derived from the glycolysis of poly(ethylene terephthalate) (PET). Dimethacrylated oligoesters (PET-GLY-DM), synthesized through the methacrylation of PET glycolysis products, were blended with Bis-GMA and triethylene glycol dimethacrylate (TEGDMA), toward the gradual replacement of Bis-GMA content. The innovative PET-GLY-DM-based resins exhibited a higher degree of conversion compared to traditional Bis-GMA/TEGDMA formulations, as measured by FTIR spectroscopy, accompanied by an increase in polymerization shrinkage, evaluated via a linear variable displacement transducer system. While the incorporation of PET-GLY-DM slightly reduced flexural strength and elastic modulus, it significantly decreased water sorption, resulting in a smaller reduction in mechanical properties after water immersion for 7 days at 37 °C and improved long-term performance. Furthermore, PET-GLY-DM resins exhibited low bisphenol-A (BPA) release measured with HPLC. It was thus confirmed that PET-GLY-DM resins derived from the glycolysis of PET wastes represent a promising alternative to conventional light-cured dental resins, offering reduced BPA release and improved water resistance. Full article

As a sustainable construction material, mudbrick can be used widely in areas where common modern construction materials are not easily accessible but high clay content soil is available. The inclusion of locally available natural fibres in mudbrick could improve its mechanical and erosion resistance performance. This study examines the performance of fibre-reinforced mudbrick from spinifex and laterite soil which are abundant in Australia. The main objective of this study is to evaluate the mechanical and durability performance of spinifex fibre-reinforced mudbricks made with Australian laterite soil, focusing on the influence of fibre content, fibre length, and cement stabilisation. Spinifex fibre length (30 mm, 40 mm, 50 mm), spinifex fibre percentage (0.3%, 0.6%, 0.9%), and cement percentage (5% and 10%) are considered as the experiment variables. Results show that compressive strength generally decreases with fibre size. In this regard, specimens with 0.3% spinifex fibre, 40 mm fibre length, and 10% cement, with an average compressive strength value of 4.1 MPa, were found to have the highest strength among all design mixes. The elastic Young’s modulus was highest for the specimens with 0.3% spinifex fibre, 30 mm fibre length, and 10% cement with a 36.1 MPa. A low amount of longer fibres was found to be more effective in reducing water absorption in samples with higher cement content. Water absorption and compressive strength results suggest that, on average, 0.3–0.5% spinifex content of size 30 mm improves both low and high cement content mudbricks properties. Full article

This study elucidated the evolution and catastrophic failure mechanisms of concrete’s mechanical properties under high-temperature and moisture-coupled environments. Specimens underwent hygrothermal shock simulation via constant-temperature drying (100 °C/200 °C, 4 h) followed by water quenching (20 °C, 30 min). Uniaxial compression tests were performed using a uniaxial compression test machine with synchronized multi-scale damage monitoring that integrated digital image correlation (DIC), acoustic emission (AE), and infrared thermography. The results demonstrated that hygrothermal coupling reduced concrete ductility significantly, in which the peak strain decreased from 0.36% (ambient) to 0.25% for both the 100 °C and 200 °C groups, while compressive strength declined to 42.8 MPa (−2.9%) and 40.3 MPa (−8.6%), respectively, with elevated elastic modulus. DIC analysis revealed the temperature-dependent failure mode reconstruction: progressive end cracking (max strain 0.48%) at ambient temperature transitioned to coordinated dual-end cracking with jump-type damage (abrupt principal strain to 0.1%) at 100 °C and degenerated to brittle fracture oriented along a singular path (principal strain band 0.015%) at 200 °C. AE monitoring indicated drastically reduced micro-damage energy barriers at 200 °C, where cumulative energy (4000 mV·ms) plummeted to merely 2% of the ambient group (200,000 mV·ms). Infrared thermography showed that energy aggregation shifted from “centralized” (ambient) to “edge-to-center migration” (200 °C), with intensified thermal shock effects in fracture zones (ΔT ≈ −7.2 °C). The study established that hygrothermal coupling weakens the aggregate-paste interfacial transition zone (ITZ) by concentrating the strain energy along singular weak paths and inducing brittle failure mode degeneration, which thereby provides theoretical foundations for fire-resistant design and catastrophic failure warning systems in concrete structures exposed to coupled environmental stressors. Full article

The earthquake of 6 February 2023, in Turkey and Syria, was catastrophic for many existing buildings. Various reasons have been given to try to understand what happened, since after 2000, changes in construction methods were introduced in this area, with the aim of improving buildings. In this research, the behavior of frame buildings with a concrete structure is analyzed. To do this, graphene oxide (GO) is introduced into traditional mixtures to improve the most deficient mechanical characteristics of traditional concrete. Laboratory tests performed with GO in traditional concrete mixtures produce improvements in the mechanical analyses performed, essential characteristics for improving the structural behavior of the frame models analyzed in this research. The mechanical results show increases of 13% in the modulus of elasticity, 22% in compression strength tests, 72% in flexural-tensile strength tests, and 14% in ductility, in addition to a 4% reduction in the density of the mixture. These characteristics are essential to understand the structural improvement of the models, helping to reduce the seismic vulnerability of the structures. To reach these conclusions, static and dynamic analyses (using records of the most intense seismic activity that occurred in Turkey in 2023) are performed on three frames of 5, 10, and 20 stories in height, considering the mechanical properties of the new mixtures (traditional and GO) obtained in the laboratory. The results obtained in the analyses of the frame models using GO in the new mixtures show improvements in the structural performance of the frames, improvements that increase with increasing height of the structures. To conclude this investigation, the analyses performed on the frame models are extended with the introduction of brick walls in the exterior bays of the bare frames, a solution commonly used to improve the resistant behavior of these structures, determining a structural improvement of the models, due to the high strength and stiffness that these infill walls impart to the bare frames. Full article

Candida infections pose a significant health threat, and conventional antifungal drugs like nystatin are limited due to poor solubility, skin permeability, and frequent dosage requirements. Nystatin effectively targets Candida species by disrupting cell membranes, but formulation issues hinder clinical use. Lipid-based vesicular carriers, or novasomes, provide controlled, prolonged drug release and enhanced skin penetration. This study focuses on developing nystatin-loaded novasomal gels as an advanced drug delivery system to enhance therapeutic efficacy, bioavailability, and patient compliance. The formulation was prepared using a modified ethanol injection technique, combining stearic acid, oleic acid, Span 60, cholesterol, and Carbopol to produce a stable transdermal gel. Comprehensive in vitro characterization using FTIR, SEM, XRD, and thermal analysis confirmed the chemical compatibility, morphological uniformity, and physical stability of the nystatin-loaded novasomal gel. Entrapment efficiency differed significantly among the formulations (p < 0.05), with F7 achieving the highest value (80%). All formulations maintained pH levels within the skin-friendly range of 5.5 to 7.0. Viscosity measurements, ranging from 3900 ± 110 to 4510 ± 105 cP, confirmed their appropriate consistency for dermal use. Rheological analysis showed a dominant elastic response, as indicated by storage modulus values consistently higher than the loss modulus. Particle size ranged from 4143 to 9570 nm, while PDI values remained below 0.3, reflecting uniform particle distribution. Zeta potential values were strongly negative, supporting physical stability. XRD studies indicated reduced crystallinity of nystatin within the formulations, while FTIR confirmed drug-excipient compatibility. SEM images showed spherical particles within the micrometer range. In vitro release studies demonstrated sustained drug release over 12 h, with F6 releasing the highest amount. The novasomal gel formulations-maintained stability for 30 days, with no notable alterations in pH, viscosity, or entrapment efficiency. Antifungal evaluation showed a larger inhibition zone (23 ± 2 mm) compared with the plain drug solution (15 ± 1.6 mm), while the MIC value was reduced (4.57 µg/mL), indicating greater potency. Skin irritation assessment in rats revealed only minor, temporary erythema, and the calculated Primary Irritation Index (0.22) confirmed a non-irritant profile. These findings suggest that the developed novasomal gel offers a promising approach for enhancing the treatment of fungal infections by enabling prolonged drug release, minimizing dosing frequency, and improving patient compliance. Full article

Coffee processing generates large volumes of spent coffee grounds (SCGs), which contain 30–40% hemicellulose, 8.6–13.3% cellulose, and 25–33% lignin, making them a promising lignin-rich filler for biocomposites. Conventional wood composites rely on urea-formaldehyde (UF), melamine–urea–formaldehyde (MUF), and phenol–formaldehyde resins (PF), which dominate 95% of the market. Although formaldehyde emissions from these resins can be mitigated through strict hygiene standards and technological measures, concerns remain due to their classification as category 1B carcinogens under EU regulations. In this study, fiber-based biocomposites were fabricated from thermomechanical wood fibers, SCGs, and ammonium lignosulfonate (ALS). SCGs and ALS were mixed in a 1:1 ratio and incorporated at 40–75% of the oven-dry fiber mass. Hot pressing was performed at 150 °C under 1.1–1.8 MPa to produce panels with a nominal density of 750 kg m⁻³, and we subsequently tested them for their physical properties (density, water absorption (WA), and thickness swelling (TS)), mechanical properties (modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond (IB) strength), and thermal behavior and biodegradation performance. A binder content of 50% yielded MOE ≈ 2707 N mm⁻² and MOR ≈ 22.6 N mm⁻², comparable to UF-bonded medium-density fiberboards (MDFs) for dry-use applications. Higher binder contents resulted in reduced strength and increased WA values. Thermogravimetric analysis (TGA/DTG) revealed an inorganic residue of 2.9–8.5% and slower burning compared to the UF-bonded panels. These results demonstrate that SCGs and ALS can be co-utilized as a renewable, formaldehyde-free adhesive system for manufacturing wood fiber composites, achieving adequate performance for value-added practical applications while advancing sustainable material development. Full article

Surface roughness influences biofilm adhesion on denture base materials, impacting oral health. Despite advances in polymeric denture materials, the effects of common cleaning protocols on their surface texture remain inadequately characterized. This study investigated the influence of toothbrush abrasion on the surface texture of dimethyl methacrylate-based (DMA, printed: V-Print dentbase), polymethyl methacrylate (PMMA, milled: VITA Vionic Base, pressed: IvoBase Hybrid), polyamide (PA, pressed: Bre.flex), and polyether ether ketone (PEEK, milled: Juvora Disc). The specimens were fabricated as polished discs. The Vickers and Martens hardness, indentation modulus, elastic and plastic part of indentation work, and indentation creep were determined. Toothbrushing simulation and surface texture analysis were conducted in three steps: 1800, 1800, and 3600 cycles using water, dish detergent, or toothpaste slurry. The surface texture parameters Sa, Sal, Sdr, Sku, and Ssk were determined using confocal laser scanning microscopy and suitable filtering (S-F and S-L surface). Sa, Sal, and Sdr showed significant changes depending on the choice of medium and the material used. The duration had a small effect (three-way ANOVA; all p < 0.001). DMA showed minor surface changes. Milled and pressed PMMA exhibited similar surface deformities due to wide valleys that were not considered critical for biofilm adhesion. PA showed the lowest and PEEK the highest Vickers and Martens hardness. However, both PA and PEEK exhibited surface changes that could promote biofilm development. These findings suggest that denture cleaning recommendations should remain material-specific. Regular surface inspections and repolishing are necessary to reduce the risk of biofilm formation on PA or PEEK-containing dentures. Full article

The polymer deposition layer (PDL) formed during inductively coupled plasma (ICP) processing significantly limits the figuring accuracy and surface quality of fused silica optics. This study investigates the formation mechanism, composition, and evolution of the PDL under varying dwell times and proposes an innovative dwell time gradient strategy to suppress roughness deterioration. A significant disparity in hardness and elastic modulus between the deposition layer and the substrate is revealed, explaining its preferential removal and protective buffering effect in computer-controlled optical surfacing (CCOS). A hybrid ICP-CCOS polishing process was developed for processing a ϕ100 mm fused silica mirror. The results show that within 33 min, the surface graphic error RMS was significantly reduced from 58.006 nm to 12.111 nm, and within 90 min, the surface roughness was ultra-precisely reduced from Ra 1.719 nm to Ra 0.151 nm. The average processing efficiency was approximately 0.63 cm²/min. Critically, a damage-free, ultra-smooth surface without subsurface damage (SSD) was successfully achieved. This hybrid process enables the simultaneous optimization of figure accuracy and roughness, eliminating the need for iterative figuring cycles. It provides a novel theoretical framework for high-precision figuring and post-ICP polymer removal, advancing the efficient fabrication of high-performance optics. Full article

With global sustainable construction growth, fully recycled coarse aggregate concrete (RCAC)—eco-friendly for cutting construction waste and reducing natural aggregate over-exploitation—has poor durability in seasonally freezing saline-soil regions (e.g., Tumushuke, Xinjiang): freeze-thaw and salt ions (NaCl, Na₂SO₄) cause microcracking, faster performance decline, and shorter service life, limiting its use and requiring better salt freeze resistance. To address this, a field survey of Tumushuke’s saline soil was first conducted to determine local salt type and concentration, based on which a matching 12% NaCl + 4% Na₂SO₄ mixed salt solution was prepared. RCAC specimens modified with fly ash (FA), silica fume (SF), and polypropylene fiber (PPF) were then fabricated, cured under standard conditions (20 ± 2 °C, ≥95% relative humidity), and subjected to rapid freeze-thaw cycling in the salt solution. Multiple macro-performance and microstructural indicators (appearance, mass loss, relative dynamic elastic modulus (RDEM), porosity, microcracks, and corrosion products) were measured post-cycling. Results showed the mixed salt solution significantly exacerbated RCAC’s freeze-thaw damage, with degradation severity linked to cycle count and admixture dosage. The RCAC modified with 20% FA and 0.9% PPF exhibited optimal salt freeze resistance: after 125 cycles, its RDEM retention reached 75.98% (6.60% higher than the control), mass loss was only 0.28% (67.80% lower than the control), and its durability threshold (RDEM > 60%) extended to 200 cycles. Mechanistic analysis revealed two synergistic effects for improved performance: (1) FA optimized pore structure by filling capillaries, reducing space for pore water freezing and salt penetration; (2) PPF enhanced crack resistance by bridging microcracks, suppressing crack initiation/propagation from freeze-thaw expansion and salt crystallization. A “pore optimization–ion blocking–fiber crack resistance” triple synergistic protection model was proposed, which clarifies admixture-modified RCAC’s salt freeze damage mechanism and provides theoretical/technical guidance for its application in extreme seasonally freezing saline-soil environments. Full article

Background: Long-term survivorship in total hip arthroplasty (THA) is influenced by implant stability and stress distribution to surrounding bone. Isoelastic acetabular components are monoblock polyethylene cups with a low elastic modulus, which were developed to reduce stress shielding and enhance periacetabular bone preservation. This systematic review aimed to evaluate the mid- to long-term clinical outcomes, wear rate, and survivorship of isoelastic cups in primary THA with a minimum follow-up of five years. Materials and methods: A systematic literature search was performed in April 2025 across PubMed, Embase, Cochrane Library, and Google Scholar following PRISMA 2020 guidelines. Inclusion criteria comprised clinical studies on isoelastic acetabular cups in primary THA with a minimum of five years of follow-up. Data on survivorship, complications, clinical outcomes, wear, and radiological performance were extracted and analyzed. Risk of bias in each study was assessed through the Newcastle–Ottawa Scale (NOS) for observational studies and the Cochrane Risk of Bias 2 (RoB 2) tool for randomized controlled trials. Results: Twelve studies, encompassing 1491 hips, met the inclusion criteria. Mean follow-up was 8.1 years. Overall implant survival rate ranged from 82.7% to 100%. Mean Harris Hip Score was 92.6, with low reported pain and high satisfaction. Mean annual wear was 0.05 mm/year. Vitamin E-infused highly cross-linked polyethylene (VEHXLPE) cups demonstrated lower femoral head penetration compared to UHMWPE. A randomized trial showed reduced bone loss in the polar region with isoelastic cups versus modular titanium cups (4.9% versus 15.9%, p = 0.005). Complication and revision rates were low, though heterogeneity in cup positioning reporting and variable follow-up durations were noted. Conclusions: Isoelastic acetabular components demonstrate excellent survivorship, low wear rates, and favorable clinical outcomes at mid- to long-term follow-up. High-quality, long-term comparative studies are needed to confirm these findings across broader patient populations. Full article

Continuous-fibre-reinforced thermoplastics are attractive materials for industries to cut down on weight in structural components. Recycling these parts or trims generated during production is difficult due to the reduced properties in materials intended for high-performance applications. Our study investigates the recyclability of short-fibre-reinforced compounds made from shredded organosheets. The fibre share was varied by the addition of virgin polypropylene, and three recycling rounds via a reduced injection-moulding process and a full thermomechanical recycling process including a compounding step were compared. Organosheet cuttings were found to be able to be applied as a short-glass-fibre source for the production of composites with varying fibre shares. Up to 14,000 MPa of elastic modulus and 80 MPa of tensile strength could be achieved at a fibre content of 45 vol%. Fibre length was reduced with progressive processing, less so for lower fibre shares, and in the reduced process without the shear and stress of the compounding step. Fibres from organosheets might be present in bundles and disperse in the matrix with progressive processing, which is particularly the case without compounding processes and can also influence the mechanical properties. Full article

In this study, the mechanical and structural properties of biocomposites fabricated using transgenic sugarcane bagasse overexpressing sucrose synthesis were investigated. The bagasse fibers were extracted from the transgenic and non-transgenic (NT) sugarcane stalk, then treated with alkalization and carbonization, and their chemical composition was analyzed. The treated fibers were reinforced to produce biocomposites, and their mechanical and structural properties were evaluated by measuring tensile strength, elongation at break, modulus of elasticity and scanning electron microscopy. The cellulose content ranged from 40.6–44.2% in transgenic sugarcane and was higher than in NT sugarcane, with the highest content observed in transgenic SPS3. However, the cellulose and hemicellulose contents were reduced, and the lignin content was significantly increased after carbonization treatment. Alkalization treatment significantly increased the tensile strength, with the highest value of 30.46 MPa obtained at 9% NaOH concentration in a biocomposite fabricated from transgenic SPS3 bagasse fibers. However, carbonization of the SPS3 bagasse fibers lowered tensile strength and slightly increased modulus of elasticity in the biocomposite. Morphological analyses showed roughened fiber surfaces after alkalization and the formation of voids in the carbonized composites. These results indicate the potential of the transgenic sugarcane bagasse fibers with high cellulose content as a renewable reinforcement material for biocomposites. Full article

This study investigates the hygrothermal aging behavior and thermomechanical properties of as-manufactured glass fiber-reinforced epoxy and thermoplastic composite tidal turbine blades. The blades were previously deployed in a marine environment and subsequently analyzed through a comprehensive suite of material characterization techniques, including hygrothermal aging, dynamic mechanical analysis (DMA), tensile testing and X-ray computed tomography (XCT). Hygrothermal aging experiments revealed that while thermoplastic composites exhibited lower overall water absorption (0.78% vs. 0.47%), they had significantly higher diffusion coefficients than epoxy (2.1 vs. 12.1 × 10⁻¹³ m²s⁻¹), suggesting faster saturation in operational environments. DMA results demonstrated that water ingress caused plasticization in epoxy matrices, reducing the glass transition temperature and increasing damping (112 °C to 104 °C), while thermoplastic composites showed more stable thermal behavior (87 °C glass transition temperature). Tensile testing revealed substantial reductions in ultimate strength (>40%) for both materials after prolonged water exposure, with minimal change in elastic modulus, highlighting the role of matrix degradation over fiber reinforcement. XCT image analysis showed that both composites were manufactured with high quality: no large voids or cracks were present, and the degree of misalignment was low. These findings inform future marine renewable energy composite designs by emphasizing the critical influence of moisture on long-term structural integrity and the need for optimized material systems in harsh marine environments. This work provides a rare real-world comparison of epoxy and recyclable thermoplastic tidal turbine blades, showing how laboratory aging tests and advanced imaging reveal the influence of material and manufacturing choices on long-term marine durability. Full article