Search Results (907)

Epoxy-glass-mica composite materials are widely used as electrical insulating materials in high-voltage rotating machinery due to their layered structure and excellent dielectric properties. Taking the F-class epoxy glass with a small amount of rubber powder mica tape commonly used as the main insulation of wind turbine stator coils as the research object, 7-day, 14-day, 21-day, and 28-day low-temperature treatment tests were conducted at −50 °C. The surface morphology and chemical structure changes of the materials were characterized by SEM and FTIR, and the influence laws of low-temperature treatment on the electrical properties of the mica tape insulation materials were systematically studied. The experimental results show that the low-temperature environment will induce microcracks and interface delamination and other structural damages, but no obvious change in the chemical structure of the mica tape was observed. With the extension of the low-temperature treatment time, the electrical properties of the mica tape show a deteriorating trend, and after 28 days of low-temperature treatment, the breakdown field strength of the F-class mica tape decreased by approximately 18.5%, and the volume conductivity overall increased by about two orders of magnitude. This indicates that the microcrack defects induced by low-temperature will lead to an enhanced electrical-thermal coupling effect in the insulation structure, thereby accelerating the degradation process of the insulation material. This reveals the degradation mechanism of wind turbine stator main insulation from “structural damage” to “performance degradation” and then to “insulation aging” under low-temperature conditions, providing a theoretical basis for the design and reliability assessment of insulation systems in wind turbine generators in cold regions. Full article

The aim of this study was to evaluate setting time, hardness, solubility, bioactivity and interaction with dentin of four calcium silicate-based sealers (CSBS). Three single-phase CSBS (AH Plus Bioceramic/AHB, CeraSeal/CSL, TotalFill BC/TFL), one powder/liquid CSBS (BioRoot RCS/BRT) and an epoxy control (AH Plus Jet/AHP) were investigated. Setting time was evaluated on glass (G1) and dentin (G2) surfaces, by adding 1%wt purified water to single-phase products. For hardness measurements, the Shore-D hardness test was used. Solubility was assessed according to the ISO 6876:2012 standard. For bioactivity screening, 1-week set specimens were immersed in SBF or water (30 days/37 °C) and examined by ATR–FTIR spectroscopy. Interaction with dentin was tested by ATR–FTIR before and after contact with the sealers. For setting time in G1, all CSBS failed to comply with the ISO standard, while in G2, most materials were set in the range of 6–8 h, except for CSL. The ranking of significant differences in hardness was AHP, BRT > CSL, AHB, TFL. Regarding solubility, AHB, BRT and AHP were found to comply with the ISO standard, whereas CSL and TFL failed. For bioactivity, characteristic peaks of calcium phosphates were found in all CSBS, with TFL being the most bioactive. A chemical interaction between CSBS and dentin was registered, with a strong reduction in collagen peaks and an increase in carbonates. The CSBS tested exhibited great variance in their behaviour regarding the properties assessed, although a strong deproteinating effect was registered on dentin for all. Full article

The progressive phase-out of coal-fired power plants in Portugal has significantly reduced the availability of fly ash (FA) as a supplementary cementitious material (SCM), reinforcing the need for sustainable alternatives. Waste glass powder (WGP), characterized by its high amorphous silica content, has emerged as a promising candidate; however, most studies focus on ultrafine particles or isolated performance indicators, lacking an integrated technical, environmental, and economic assessment. This study evaluates cement pastes incorporating 25% WGP (by volume) with different particle size distributions, including fineness levels comparable to cement and FA. Mechanical performance, grinding energy demand, carbon footprint, and cost were systematically analyzed. The results indicate that WGP is technically viable as an SCM, with a median particle size (D₅₀) of approximately 48 µm providing the most balanced performance. Although finer particles enhance pozzolanic reactivity, the associated increase in grinding energy and economic cost offsets these gains. The findings demonstrate that optimizing particle size, rather than maximizing fineness, enables a technically robust and industrially realistic use of WGP. This approach supports circular economic strategies and contributes to the decarbonization of the construction sector by identifying an efficient replacement pathway for FA under resource-scarcity conditions. Full article

High-speed laser cladding (HLC) technology can provide high cooling rates and low dilution rates for the preparation of metastable Fe-based amorphous phases. In this work, the effects of Ta content on the microstructure, mechanical properties, and soft magnetic performance of Fe-based amorphous alloys were systematically investigated. The results indicated that Ta remained uniformly dispersed within the FeSiB amorphous powder, and no new phases were formed after mechanical ball milling. The higher mixing enthalpy of Ta and its atomic radius difference from other elements (such as Fe, Si, B) were beneficial in improving glass-forming ability (GFA), and with an increase in Ta element content from 0% to 2%, 4% and 6%, the amorphous phase content was 48.6%, 51.5%, 60.4% and 54.8%, respectively. The average microhardness of the coating with a Ta content of 4% was 1310 HV_0.2, which was 50HV_0.2 higher than before; in addition, the wear rate reduced from 2.21 × 10⁻⁴ mg·N⁻¹·m⁻¹ to 2.06 × 10⁻⁴ mg·N⁻¹·m⁻¹. Also, corrosion tests showed that the coating with a Ta content of 4% displayed superior corrosion resistance compared to that before the Ta addition. However, because the element Ta could alter the local electronic environment and enhance the local magnetic anisotropy of FeSiB, the saturation magnetic flux density (Ms) decreased from 1.64 T to 1.56 T, and the coercivity (Hc) increased from 0.9 A/m to 1.3 A/m, which caused degradation of the soft magnetic properties. Full article

Zinc deficiency is recognized as a global public health concern, affecting populations of all ages. This study aims to develop zinc supplements (nutraceuticals) based on by-products of the fruit and vegetable processing industry. Dehydrated apple and beetroot pomace powders were enriched with vitamin C and zinc via fluid-bed wet granulation, producing granules with substantially improved flowability (Carr’s index reduced by up to 45%, Hausner ratio by up to 25%, while the bulk and tapped density were reduced by up to 25% and 40%, respectively). Microbiological and long-term storage stability was demonstrated by low water activity (aw) (≤0.3), moisture content (<10%), and glass transition temperatures (T_g = 29–34 °C) that were well above standard storage conditions. The formulated nutraceuticals exhibited stronger antioxidant activity compared to the starting powders, as well as significant anti-hyperglycemic activity. Furthermore, the enhanced bioaccessibility of zinc was confirmed upon in vitro digestion of granulated samples, using atomic absorption spectrometry and differential pulse voltammetry. The present findings demonstrate that apple and beetroot pomaces can be successfully valorized as sustainable and functional matrices for zinc enrichment, being free of gluten, artificial sweeteners, colorants, preservatives, anti-caking agents, and anti-nutritional factors such as phytic acid. Full article

Background: Latent fingerprints are crucial forensic evidence, but their stability can be affected by environmental factors such as direct sunlight. The findings indicate that prolonged sunlight exposure may be associated with reduced fingerprint quality and forensic usability. Methods: A total of 322 groomed latent fingerprints from one volunteer were deposited on non-porous glass and exposed to direct sunlight for 1–7 weeks. A control sample was preserved without exposure. Fingerprints were developed using magnetic powder and assessed by minutiae counts. Usability was classified according to Slovak forensic standards. Statistical analysis was conducted using the Friedman test and Durbin–Conover test. Results: Significant differences in minutiae counts were observed between the control and selected exposure intervals (weeks 1, 3, 4, 6 and 7; p < 0.05). The degradation pattern was not linear, with initial decreases followed by stabilization in later weeks. Despite statistical differences, 99.38% of fingerprints remained usable for identification, and none were classified as non-usable. Conclusions: Prolonged direct sunlight exposure did not substantially reduce the identificatory value of groomed latent fingerprints on glass. Even after several weeks, most fingerprints retained sufficient ridge detail for personal identification, supporting their evidential relevance in outdoor forensic contexts. Full article

This study explores the potential utilization of bioactive glasses using different dopant ions and ketoprofen for both tissue ingrowth and local drug delivery. Four different compositions of vitreous powders were synthesized by the sol–gel combined with the emulsion method, in the presence of the ionic surfactant cetyltrimethylammonium bromide (CTAB), differing by dopant ions: SiO₂- P₂O₅-CaO-(ZnO-MgO). This study investigates the chemical–mineralogical, morphological, and structural characteristics, as well as the biological properties of vitreous materials obtained. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) data analysis confirmed the vitreous nature; scanning electron microscopy (SEM) micrographs correlate with the results of physical absorption with N₂, and the compositions used for the synthesis of the powders all showed for the samples with MgO lower porosity. Biological testing demonstrated biocompatible behavior towards osteoblast cells, (MG-63 type), inducing a slight acceleration of the mineralization phenomenon in the osteoid of the cells compared to the negative control, with cell viability for all the samples higher than 50%. Preliminary release analyses performed by UV–Visible spectroscopy showed a characteristic controlled release profile with prospects for a potential drug delivery system. The zinc–magnesium co-doped sample exhibits optimal performance in both osteogenic promotion and drug delivery, presenting potential for integrated bone repair and local drug administration. This study concludes that the synthesized bioglass exhibits promising characteristics for potential applications in tissue engineering with local drug delivery. Full article

The transition toward low-carbon and resource-efficient construction materials has intensified interest in geopolymer binders incorporating industrial and post-consumer wastes. Waste glass powder (WGP), a silica-rich component of the global glass waste stream, has emerged as a promising circular-economy precursor in alkali-activated systems; however, reported durability trends remain inconsistent and are often interpreted without mechanistic integration. This review synthesises current knowledge of WGP reactivity, gel chemistry, and long-term performance through an explicit reaction–transport–ageing (R–T–A) framework that links dissolution behaviour and phase assemblage development to pore connectivity, ion ingress, and time-dependent degradation. Under alkaline activation, the amorphous structure of WGP promotes silica release, modifying Si/Al ratios and governing the formation of N-A-S-H or hybrid N-A-S-H/C-(A)-S-H gels. These reaction products determine transport characteristics and ageing evolution, which collectively control chemical resistance, chloride ingress, alkali–silica reaction-type instability, and dimensional stability. Variability across studies is shown to arise from imbalances in particle fineness, replacement level, precursor chemistry, and activator design rather than intrinsic inconsistency in WGP behaviour. The R–T–A framework clarifies how reaction completeness, pore network architecture, and long-term phase stability interact to produce system-dependent durability outcomes. WGP demonstrates strong potential as a circular-economy precursor in alkali-activated binders; however, reliable structural application requires durability-informed mix design grounded in coupled reaction–transport–ageing mechanisms and supported by extended exposure testing under realistic service conditions. Full article

In order to realize the large-scale resource utilization of solid waste in building materials, geopolymer mortar was prepared by alkali excitation technology with municipal solid waste incineration fly ash (MSWIFA), waste glass powder (WGP) and metakaolin (MK) as raw materials. After 28 days of curing, compressive strength and heavy metal leaching concentration of MSWIFA-WGP-MK geopolymer mortar were measured. The microstructure and phase composition of geopolymer samples were examined using scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction analysis. The results demonstrated that the compressive strength of mortar increased as the MSWIFA content decreased and the alkali activator (AA) content increased. The mortar containing 30% MSWIFA and 35% AA achieved the highest 28-day compressive strength of 70.9 MPa. The high compressive strength was strongly associated with the compact microstructure, as revealed through scanning electron microscopy. The heavy metals in MSWIFA were solidified well in geopolymer matrix, and the leaching concentrations of heavy metals were below the regulatory thresholds. Based on the test results of mortars, concrete pavement bricks were produced. The performance of the optimized concrete paving brick satisfied requirements of the specification. The results indicated that the MSWIFA and WGP can be utilized in building materials. Full article

This study investigates an eco-friendly rapid-setting concrete developed for emergency repair and accelerated post-disaster reconstruction. The proposed material concept combines a low-emission multicomponent cement, CEM V/A (S-V) 42.5 N-LH/HSR/NA, with a hybrid aggregate skeleton composed of crushed granite and waste soda–lime glass, as well as a waste-derived silicate additive system based on aqueous sodium silicate, glass dust and glass powder. One reference mixture (R) and five modified mixtures (M1–M5) were designed to assess the effects of partial replacement of natural aggregate by glass aggregate and of the dosage of the silicate-based additive system on concrete performance. The experimental programme included setting time, compressive strength, splitting tensile strength, water absorption, freeze–thaw resistance and microstructural observations. Among the modified concretes, the mixture containing 5 vol.% glass aggregate (M1) showed the most favourable mechanical performance after 28 days, reaching a compressive strength of 95.1 ± 2.4 MPa and a splitting tensile strength of 4.82 ± 0.29 MPa, compared with 45.5 ± 0.8 MPa and 2.18 ± 0.11 MPa, respectively, for the reference concrete. Higher glass contents reduced strength relative to M1, but the modified mixtures still maintained satisfactory performance. The silicate-based system significantly affected setting behaviour; in mixture M5, the initial and final setting times were reduced from 380 ± 5 min and 497 ± 5 min to 213 ± 5 min and 307 ± 5 min, respectively. The results show that the combined use of CEM V cement, waste glass and silicate-based waste-derived additives can produce concretes with rapid-setting, high strength and satisfactory durability-related properties. The developed material may therefore be considered a promising solution for selected rapid-repair and reconstruction applications, particularly in lightly reinforced or unreinforced concrete elements requiring fast restoration of functionality. Full article

The disposal of end-of-life fluorescent lamps presents significant environmental challenges due to their mercury (Hg) content and the loss of valuable rare earth elements (REEs) contained in phosphor powders, highlighting the need for sustainable recycling strategies. This study proposes an integrated hydrometallurgical process for simultaneous mercury removal and material recovery from spent fluorescent lamps. Various leaching agents were initially evaluated for mercury dissolution, and 10% NaOCl was identified as the most effective solution. The optimized system was applied to linear T8 lamps using a combined milling–leaching approach, followed by size-based separation of metallic, glass, and phosphor fractions. Dissolved mercury was precipitated at pH 11 using Na₂S, forming crystalline α-HgS (cinnabar), as confirmed by XRD, and reducing the residual mercury concentration to 2.7 µg/L. The metallic fraction was recovered as an aluminum-based alloy containing 20.6 wt.% Cu and 10.9 wt.% Zn with low iron content, while the phosphor-rich fraction yielded approximately 50% REE extraction, followed by oxalate precipitation of yttrium-based compounds. The developed process enables efficient mercury stabilization and selective recovery of valuable materials, supporting environmentally secure and resource-efficient fluorescent lamp recycling. Full article

The incorporation of supplementary cementitious materials (SCMs) is a key strategy for enhancing the performance and sustainability of cement-based systems. This research examines the mechanical behavior, microstructural evolution, and durability-related properties of cementitious materials incorporating waste glass powder (WGP) and metakaolin (MK) as partial replacements of Portland cement. Cement pastes were evaluated for compressive strength at 7 and 28 days, while microstructural analysis at 28 days employed gas adsorption and scanning electron microscopy (SEM). Based on the compressive strength performance of the cement pastes, ternary WGP–MK mortars were assessed for consistency, flexural and compressive strength, water absorption, and porosity at 28 and 60 days. Results indicate that MK accelerates early-age strength, whereas WGP enhances long-term performance and pore structure refinement. Binary and ternary systems exhibited reduced accessible pore volume, enhanced microstructural homogeneity, and lower water absorption with curing time. The findings demonstrate that WGP-MK blends support clinker reduction without compromising performance, advancing circular economy goals in construction. Full article

The rising prevalence of Candidozyma auris and Candida parapsilosis, characterized by high surface persistence and biofilm-forming capabilities, challenges the efficacy of standard laundry and surface disinfection protocols. This study evaluated the effectiveness of laundry processes according to EN 17658 at 20 °C, 30 °C and 40 °C and two surface disinfectants (bead assay for biofilms) against two Candida albicans strains, C. parapsilosis, and C. auris. Results indicated that C. auris is more resilient than other strains, surviving laundry treatment with activated oxygen bleach at 40 °C; maximum efficacy required a colour powder detergent supplemented with a bleach-releasing additive at 40 °C. While alcohol- and aldehyde-based surface disinfectants were effective per EN 13697 criteria, their efficacy against biofilms—tested on glass, stainless steel, polypropylene, and PTFE—was highly dependent on both the strain and the surface material. These findings demonstrate the reduced susceptibility of C. auris to standard laundry disinfection and highlight that biofilm eradication is a complex process influenced by strain-specific attributes and surface characteristics. Full article

This study investigates the application of artificial intelligence for predicting the compressive strength of a high-performance, eco-efficient engineered cementitious composite (ECC), designated mix S8-1, A. The composite incorporates supplementary cementitious materials and alternative aggregates derived from recycled glass waste. The binder system combines waste glass powder and silica fume, while the aggregate fraction includes recycled cobalt glass. An extensive experimental program involving 14 mixtures tested at 7, 28, 56, 90, and 120 days was performed to establish the reference mechanical and rheological properties. Mix S8-1, A achieved strength class C60/75 and workability corresponding to consistency class S4. To substantiate long-term performance, microstructural and chemical analyses were conducted on specimens preserved since 2011, using scanning electron microscopy (SEM) and X-ray fluorescence (XRF). The results confirmed a stable, densified microstructure, evidencing the long-term durability of the patented ECC formulation. For predictive modeling, a shallow feedforward artificial neural network with three hidden layers was developed and trained on 70 dataset entries representing mixture proportions and curing ages. Model performance was evaluated using cross-validation, achieving a coefficient of determination (R²) of 0.968, a mean absolute error of 1.96 MPa, and a root mean square error of 2.52 MPa. The results demonstrate that AI-based approaches can accurately predict the compressive strength of high-performance, environmentally sustainable ECCs incorporating recycled glass constituents, supporting both performance optimization and resource-efficient material design. Full article

Polymer–ceramic composites based on cyanate ester resins have attracted increasing attention for high-frequency electronic applications due to their low dielectric loss, thermal stability, and dimensional reliability; however, achieving a targeted dielectric constant while maintaining low loss remains a key challenge. In this study, transparent glass powders and BaTiO₃ ceramic fillers were incorporated into a cyanate ester matrix to systematically investigate structure–property relationships and optimize dielectric performance for antenna-related applications. Transparent glass powders were synthesized via a melt-quenching route and combined with submicron BaTiO₃ particles, while both fillers were surface-modified using 3-triethoxysilylpropyl isocyanate (TESPI) to enhance interfacial compatibility. Composite samples containing 5–30 wt% total filler were fabricated and characterized by XRD, FTIR, tensile testing, dielectric measurements, and SEM/EDX analyses. The results demonstrate that TESPI surface modification promotes strong interfacial bonding and homogeneous filler dispersion within the cyanate ester matrix. An optimal balance between mechanical integrity and dielectric performance was achieved at 15 wt% total filler loading (K3), exhibiting a dielectric constant close to 10 and the lowest dielectric loss (tan δ ≈ 0.0047 at 1 MHz). Microstructural observations confirm that excessive filler loading leads to agglomeration and increased dielectric loss. Overall, the combined use of transparent glass and BaTiO₃ fillers, together with effective interfacial engineering, enables precise tuning of dielectric properties in cyanate ester composites for high-frequency electronic applications. Full article