Search Results (6,523)

The occupational health implications of solar photovoltaic (PV) recycling remain critically under-investigated. This study assessed occupational exposure across the PV recycling value chain in Taiwan, evaluating primary mechanical dismantling and downstream reuse sectors (glass milling and controlled low-strength material [CLSM] batching). Area and personal samples were analyzed for total dust, respirable dust, and trace heavy metals. Results indicated that primary mechanical crushing yielded relatively low ambient dust and negligible toxic heavy metal (e.g., Pb, Cd) aerosols, attributed to the macroscopic ductility of metallic ribbons and EVA shock-absorbing properties. Conversely, a critical “hazard transfer” phenomenon was empirically identified downstream, where intensive secondary grinding and aggregate blending in the downstream reuse sector (glass milling and CLSM batching) systematically shifted the aerodynamic particle size distribution, causing the respirable dust fraction to surge to 38.9–72.6%. The pursuit of zero-waste material circularity inadvertently amplifies highly dispersive, respirable dust hazards in downstream sectors, necessitating targeted occupational exposure controls. Full article

The electrification of high-temperature industrial processes requires refractory materials that combine thermal stability with tailored electrical functionality. In this study, Ta/Nb-Al₂O₃ composites were prepared by spark plasma sintering (SPS) to investigate densification, metal-phase deformation, electrical conductivity and percolation behavior. Coarse, fine and superfine alumina powders were combined with tantalum or niobium and sintered at 1300–1600 °C for 5 min with 50 MPa uniaxial pressure. The results show that the alumina particle size and morphology strongly influence the formation of conductive metal networks. Coarse alumina promotes deformation and elongation of the metallic phase, thereby improving metal-phase connectivity and lowering the operational percolation threshold. Fine and superfine alumina enhance densification but can delay percolation by embedding metal particles in a dense ceramic matrix. Combining these fractions, both effects can be balanced, enabling improved densification while maintaining effective conductive pathways. An operational percolation threshold of 7.5 vol.-% was obtained for Ta/coarse alumina, indicating highly effective metal-phase connectivity after SPS. Microstructural analysis supports the interpretation that matrix-controlled metal-particle deformation and spatial distribution govern the electrical response. Tailored alumina matrix design can reduce the refractory metal content required for conductive ceramic–metal composites. Full article

This study investigates the preparation and characterization of tin micro- and nanoparticles with an emphasis on phase-transformation-induced particle formation and chemical purity. Microparticles were generated through repeated phase transformations between β-Sn (white tin) and α-Sn (gray tin), exploiting the associated volumetric changes to induce fragmentation and particle size reduction. The evolution of particle size distribution was systematically analyzed as a function of transformation cycles. The data were analyzed using the modified Johnson–Mehl–Avrami–Kolmogorov equation, and the saturation particle size corresponds to the grain size of the original tin sheet. The phase transformation was induced homogeneously by α-Sn particles and heterogeneously by InSb, and the results were comparable. The influence of the surrounding atmosphere was studied. The increase in oxygen content during repeated phase transformation was measured. In parallel, tin nanoparticles were synthesized via a solution-based route using ammonium hexachlorostannate as a precursor. The nanoparticles precipitated from this solution at mild temperatures during the β-Sn to α-Sn transformation at 13.2 °C. Both micro- and nanoparticles were characterized in terms of morphology and size distribution. The results provide insight into the relationship between phase transformation and particle size reduction mechanisms, and offer a controllable pathway for the preparation of tin particles across micro- and nanoscale regimes. Full article

Partial substitution of ordinary Portland cement (OPC) with supplementary cementitious materials is a key strategy for reducing the clinker factor and associated CO₂ emissions from cement production. This study investigates the feasibility of incorporating untreated electric arc furnace steel slag (EAF-SS), collected from a steel plant in Kenitra, Morocco, as a partial replacement of OPC in Portland cement. The material was characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), and particle size distribution (PSD) analysis. Cement blends containing 2–15 wt.% EAF-SS as a replacement of OPC were prepared and tested in accordance with EN standards to evaluate consistency, setting time, density, porosity, and compressive and flexural strengths at 2, 7, and 28 days. Increasing EAF-SS content from 2% to 15% slightly delayed the initial setting time by 3–17 min and reduced early-age compressive strength from 36 MPa for OPC to 26 MPa for the 15% blend at 2 days. At 28 days, mixtures containing 2–5% EAF-SS achieved compressive strengths of 42–52 MPa, satisfying class 42.5R requirements, whereas higher replacement levels (10–15%) reduced strength to 36–39 MPa. Flexural strength decreased from 7.5 MPa for OPC to 5.7 MPa for the 15% blend at 2 days and to 7.3 MPa at 28 days, while density decreased by 2–4% and total porosity increased from 12% to 18% with increasing slag content. Drying shrinkage decreased slightly with increasing EAF-SS content, from 630 µm/m for OPC to 560 µm/m for BC15 at 28 days, suggesting a modest beneficial effect on dimensional stability. The investigated slag exhibited an Fe₂O₃ content of ~57 wt.%, substantially higher than values commonly reported for many European and Chinese EAF slags. Accordingly, the novelty of the present work lies not simply in the geographical origin of the material, but in the standardized experimental assessment of a compositionally atypical, untreated, Fe-rich EAF steel slag used directly as a partial replacement of OPC in Portland cement. The study is intended as a first performance-oriented evaluation of this Moroccan by-product under EN-based testing conditions, rather than as a complete mechanistic or environmental assessment. These findings support the feasibility of low-level EAF-SS incorporation in blended cement and indicate a potential contribution to clinker factor reduction and associated CO₂ savings under the assumptions adopted in this study. However, the environmental benefit assessment remains preliminary and should be confirmed by full life-cycle and leaching analyses. Full article

This study presents a comparative evaluation of geopolymer foams incorporating either commercially available shape-stabilized phase change materials (PCMs) or laboratory-developed diatomite–paraffin PCM granules with controlled particle size fractions ranging from <1.6 mm to >2.5 mm. All PCM variants were incorporated at a constant dosage of 7.5 wt.% to isolate the influence of PCM type on the properties of the resulting composites. The commercial materials comprised PX-4, PX15, and PX20 (Rubitherm Technologies GmbH), whereas the laboratory-developed PCM consisted of paraffin immobilized within a porous diatomite matrix to produce granular shape-stabilized composites. The experimental program included the determination of bulk density, total porosity, pore size distribution, thermal conductivity (λ), thermal resistance (R), specific heat capacity (Cp), and compressive strength. The pore structure was characterized by mercury intrusion porosimetry (MIP), while the morphology and dispersion of PCM particles within the geopolymer matrix were investigated using scanning electron microscopy (SEM). All mixtures were produced using the same alkali-activated matrix and identical curing conditions, with the PCM content maintained at 7.5 wt.%. The results demonstrated that the type of PCM significantly affected the microstructure and thermophysical performance of the geopolymer foams. The laboratory-developed diatomite–paraffin PCM provided the most favorable thermal insulation performance, exhibiting the lowest thermal conductivity (0.095 W/m·K) together with the highest thermal resistance (0.278 m²·K/W). In contrast, the commercial PX15 and PX20 materials exhibited the highest specific heat capacities (1.740 and 1.778 kJ/kg·K, respectively), indicating superior thermal energy storage capability. In addition, the estimated production cost of the laboratory-developed PCM (2.5–4.0 EUR/kg) was substantially lower than that of the commercial PX materials (approximately 20 EUR/kg), highlighting its potential as a cost-effective alternative for sustainable, energy-efficient building materials. These findings demonstrate that both commercial and laboratory-developed PCM systems can effectively enhance the functionality of geopolymer foams, although they provide different balances between thermal insulation, heat storage capacity, and production cost. Full article

Microplastic pollution in tropical urban rivers has become an increasing environmental concern due to rapid urbanization, inadequate waste management, and hydrological transport processes. This study investigated the occurrence, characteristics, and spatiotemporal distribution of microplastics in the Can Tho River, Vietnam, along an urban–peri-urban–rural gradient during dry and wet seasons. Surface-water samples were collected at 15 sites and analyzed for microplastic abundance, density, shape, color, and size composition using stereomicroscopic identification and statistical analyses. Microplastics were detected at all sampling sites in both seasons, indicating widespread contamination throughout the river system. Although seasonal differences in overall abundance and density were not statistically significant at the basin scale, clear spatial variability was observed, particularly in urban and peri-urban regions. Fibers and fragments were the dominant shapes, while blue, purple, and green particles were the most common color categories. Particles larger than 1000 µm accounted for the largest proportion of detected microplastics, and continuous size-distribution analysis revealed broadly similar overall distributions, although a greater proportion of smaller particles was observed during the dry season. The results suggest that hydrological conditions, urbanization, and land-use characteristics may contribute to the observed spatial and seasonal patterns of microplastic distribution in the Can Tho River. Peri-urban zones exhibited the greatest seasonal variability, highlighting their role as transitional areas that may influence microplastic redistribution in tropical river systems. This study provides baseline information for understanding microplastic pollution in the Mekong Delta and supports future river management strategies. Full article

Particle size distribution (PSD) is a key determinant of aerosol optical properties and plays an important role in optical sensing and environmental monitoring. However, estimating PSD from light scattering measurements remains a challenging inverse problem due to its ill-posed nature and sensitivity to noise. To achieve the objective, this study proposed a physics-informed, data-driven inversion framework for PSD reconstruction using multi-angle light scattering signals generated from Mie scattering simulations. Synthetic datasets were generated using Johnson–SB, lognormal, and bimodal lognormal PSDs under various optical conditions, and the resulting scattering intensities were used to train machine learning models, including Random Forest (RF), Extreme Gradient Boosting (XGBoost), and Support Vector Regression (SVR). The proposed framework was evaluated using both point-wise error metrics and distribution-based metrics, including Kullback–Leibler divergence and Wasserstein distance. The results showed that RF and XGBoost consistently achieved the highest reconstruction accuracy, with R² values exceeding 0.98 across different PSDs, and significantly outperformed conventional linear baseline methods, including Ridge regression (representing Tikhonov regularization) and Non-negative Least Squares (NNLS). Additional experiments using lognormal and bimodal lognormal PSDs further confirmed the distributional generalization capability of the proposed model. The reconstructed PSDs also showed strong agreement with the reference distributions and remained robust under Gaussian, lognormal, and combined noise perturbations of up to 20%. Therefore, integrating physics-based scattering simulations with machine learning provided an accurate and robust solution for the inverse Mie scattering problem in optical particle characterization. Full article

To accurately characterize the effects of polydisperse particle sizes, multimineral composition, and angular morphology on the packing structure of lunar regolith, a two-dimensional sequential packing method based on random convex octagons is proposed. The method establishes a particle parameter system using data from Chang’e-5 samples and generates polygonal particle models with controllable angular features through radial perturbation. On this basis, a sequential packing algorithm based on available arc analysis is developed. Non-overlapping particle insertion is achieved via geometric envelope constraints, and progressive filling is realized through effective arc sampling. Meanwhile, a packing control coefficient is introduced to enable continuous regulation of packing density. Results show that the proposed method can generate highly dense particle assemblies, with a maximum packing density of 0.8757 and an average coordination number of approximately 3.18, capturing the structural characteristics of “high compactness–low coordination number” in polydisperse angular particle systems. The algorithm exhibits a computational complexity of O(N^1.628), demonstrating high efficiency. Furthermore, contact area and contact strength are quantitatively characterized through contact contour extraction and an equivalent bow-shaped model. Radial distribution function and contact statistics indicate that the generated structures possess good randomness and physical consistency. The proposed method provides a high-fidelity mesoscopic structure generation approach for discrete element modeling (DEM) of lunar regolith and establishes a reliable foundation for analyzing the mechanical behavior of granular systems. Full article

Mixed cotton–polyester textile waste remains difficult to recycle because processes that recover synthetic polymers often leave the cotton fraction underused, while cellulose extraction methods may compromise the polyester component. This study investigates whether cotton in such blends can be converted into high-quality microcrystalline cellulose while retaining the potential value of the recovered polyester fraction. Cotton waste and cotton–polyester blends were treated using aqueous sulfuric acid at different conditions: from 15 to 20% acid concentration and from 70 to 80 °C for five to ten hours. The recovered microcrystalline cellulose was characterised and compared to commercial microcrystalline cellulose, while the polyester fraction was assessed using tensile testing. Enzymatic hydrolysis and a dimethyl sulfoxide co-solvent approach were evaluated as alternatives. The aqueous acid process yielded 82 to 97% microcrystalline cellulose from cotton waste and up to 51% from blended waste. The recovered cellulose showed around 10% higher crystallinity than commercial material and a similar particle size distribution, although morphology depended on the feedstock. The polyester fraction showed only minor reductions in tensile performance. The novelty of this study lies in the demonstration of a simple, ionic-liquid-free, single-reagent route that valorises both material streams from cotton–polyester textile waste. Full article

Reliable prediction of reservoir properties and internal reservoir architecture is critical for the exploration and appraisal of hydrocarbon accumulations characterized by complex geological structure and high uncertainty in the spatial distribution of reservoir rocks. This study presents a hybrid event-process algorithm for sedimentary-process modeling of deep-water turbidite systems and demonstrates its applicability to the Achimov Formation in Western Siberia. The proposed methodology combines a regular-grid representation of reconstructed paleotopography with a Lagrangian description of sediment particles and Eulerian reconstruction of flow fields. The terrigenous material is represented by four grain-size fractions: coarse-grained sand, medium-grained sand, silt, and clay. Application of the algorithm made it possible to reproduce the internal architecture of deep-water submarine fans. The modeling results reflect the main principles of lithological differentiation in turbidite bodies: sandy fractions are deposited predominantly in the proximal part of the system, whereas the pelitic component is transported toward more distal areas. The resulting distributions of total thickness and net-to-gross ratio make it possible to delineate areas characterized by increased reservoir development. Comparison of the modeled results with well data showed reliable agreement: for total thickness, the coefficient of determination was R² = 0.83 with an RMSE of 4.5 m, while for the net-to-gross ratio, it was R² = 0.81 with an RMSE of 0.08. The model shows that the internal architecture is controlled by morphodynamic feedback between paleorelief inheritance, depocenter filling, and subsequent flow diversion, which leads to compensational lobe stacking. These results indicate that the developed algorithm can be applied to the modeling of deep-water submarine fans. The proposed approach contributes to reducing geological uncertainty and can be used to provide a more reliable basis for identifying prospective zones when planning exploration programs. Full article

A study was conducted to characterize the performance of a HydroFloat^® coarse particle flotation (CPF) cell using rougher tailings samples from an industrial copper mining operation. The work involved measuring internal hydrodynamic variables under a wide range of operating conditions. The effect of different operational and hydrodynamic conditions on the metallurgical performance of the HydroFloat^® cell was also evaluated. Gas dispersion measurements, such as bubble size distribution, superficial gas velocity (J_g), superficial area flux (Sb), and residence time distribution (RTD), were recorded, enabling a detailed analysis of the cell’s operation. Results show that copper recovery is strongly influenced by the superficial gas velocity (J_g) and the superficial liquid velocity (J_l). It was observed that the bubble diameter (d₃₂) remained relatively constant at 0.5 mm across all operating conditions, which is well below typical bubble sizes for conventional flotation cells. This suggests that contrary to what may be expected, in this kind of machine, small bubbles are able to float coarse particles. Bubble image inspection suggests that the HydroFloat^® cell creates conditions conducive to bubble–particle aggregates, which would explain how small bubbles can float coarse particles. This study contributes to the understanding of CPF and establishes a framework for optimization in copper concentrators. Full article

This study compares five Si–Me infiltration coatings, Si:Mo (1:4), Si:Ti (1:1), Si:Zr (1:5), Si:Ta (1:1), and Si:W (1:5), deposited on C/C sonotrodes for ultrasonic atomization of CuSn8. The coatings were evaluated in terms of phase constitution, microstructure, wettability, nanoindentation response, and powder-production performance. XRD showed that the coatings formed distinct multiphase reaction layers, with Si:Ta (1:1) being the most silicide-dominated system, while the other coatings contained carbide or silicide–carbide phases. Metallization strongly improved the surface wettability of C/C, especially for Si:Zr (1:5) and Si:W (1:5). Nanoindentation indicated the most favorable H/E* and H³/E*² descriptors for Si:W (1:5) and Si:Mo (1:4). All coatings enabled high powder yields in single-run atomization tests, while apparent differences in particle-size distribution were observed among the coating conditions. Overall, the results show that coating selection for ultrasonic atomization should combine phase constitution, surface-state descriptors, near-surface mechanical response, layer retention, and process performance. Within the investigated conditions and the limitation of single-run atomization experiments, Si:W (1:5) emerged as the most promising and best-balanced coating candidate, while Si:Ta (1:1) and Si:Mo (1:4) remained relevant alternatives. Full article

Low-melting-point impurities in powder feedstock can trigger local melting phenomena in laser powder bed fusion (LPBF) parts and may initiate defects in printed components. Here, we combine bulk chemistry with automated, high-throughput particle-by-particle SEM/EDS to identify and quantify Sn-containing impurity particles in two gas-atomized Al–Mg–Zr powder batches with different bulk Sn levels. The aim was not to establish a direct batch-to-batch performance comparison, but to clarify whether Sn was uniformly distributed among the powder particles or concentrated in rare impurity particles. Although ICP analysis indicated only 0.07 ± 0.02 wt.% Sn in the Sn-higher batch and <0.01 wt.% Sn in the Sn-lower batch, automated SEM/EDS screening of 20,001 particles per batch revealed that Sn was present as a very small number of highly enriched particles with Sn > 45 wt.% (eight particles in the Sn-higher batch and three particles in the Sn-lower batch). In the Sn-higher batch, Sn-rich particles were predominantly spherical and fell within the LPBF feedstock size window (Dmax ≈ 25–40 μm), implying that standard sieving would not remove them. BSE imaging and EDS mapping of polished sections and fracture surfaces of LPBF specimens built from the Sn-higher batch revealed spatially localized Sn-rich features associated with pores and Sn-rich phases on the fracture surface, supporting a direct powder-to-part transfer. These results demonstrate that low bulk impurity levels can mask highly localized, particle-scale contamination and highlight the need for particle-level compositional screening to support robust powder qualification and reuse decisions in LPBF. Full article

A biological/synthetic hybrid graft copolymer was obtained by grafting poly(acrylic acid) (PAA, synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization) to amylopectin (AMP). The novel graft copolymer presents amphiphilic properties due to the inherent insolubility of AMP in water and was further utilized as a mediator for the synthesis of gold nanoparticles (AuNPs) following an environmentally friendly in situ procedure. The AMP-g-PAA copolymer formation by the interaction of the PAA end groups with the C(6)-OH groups on an AMP backbone was confirmed by Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) and 1D (proton (¹H NMR) and carbon (¹³C NMR) nuclear magnetic resonance, and Distortionless Enhancement by Polarization Transfer (DEPT)) and 2D (correlation (COSY) and heteronuclear single quantum coherence (HSQC)) spectroscopies. The calculated degree of substitution of 1.17 suggests that the grafting was done at one OH from the three in an anhydroglycosidic unit (AGU) (preferably at that in C6 position), with a mean grafting efficiency of 76%. Additional information obtained using thermogravimetric analysis shows that the thermal decomposition of AMP-g-PAA occurs in two steps, with a residual mass of ~16 wt% at 700 °C, higher than AMP or PAA, indicating increased thermal stability of the copolymer. Dynamic and electrophoretic light scattering (DLS and ELS) measurements were used to determine the hydrodynamic size and ionic charge of the AMP-g-PAA self-assemblies in aqueous solution as well as their stability. The AMP-g-PAA was subsequently tested as a reducing agent in the environmentally friendly synthesis of AuNPs in aqueous solution, at different incubation temperatures, reaction duration, and inorganic/polymer weight ratios. The development of the surface plasmon resonance band of AuNPs, observed in UV–vis spectra, was consistently monitored over the reaction time. DLS analysis indicated time-dependent changes in the AuNPs’ particle size distributions, while scanning transmission electron microscopy confirmed that the AuNPs formed at the inorganic/polymer weight ratio of 0.36 and at 60 °C were predominantly well-dispersed, spherical-shaped nanoparticles. The AuNPs synthesized in situ within the copolymer matrix did not introduce additional cytotoxicity compared to the parent copolymer alone, with the composites representing a promising safety baseline for further investigation in biomedical applications. Full article

The association of HDL and its subfractional profile with cardiovascular health, particularly atherosclerosis, is well established; however, its association with post-exercise heart rate response remains underexplored. This cross-sectional study investigated whether HDL subfraction distribution is associated with post-exercise heart rate dynamics. We analyzed 304 adults, stratifying HDL into ten subfractions and 3 subclasses using the Lipoprint^® system. Heart rate was measured at rest (HR_rest), immediately after the YMCA 3-min step test (HR_aft), and during recovery (HR_5min and HR_10min) to calculate ΔHR. Multiple regressions were applied with False Discovery Rate correction. Participants with a more favorable post-exercise heart rate profile exhibited higher ApoA-I levels and favorable lipid ratios. Subfractions spanning the large and intermediate ranges (HDL-3 to HDL-5) were inversely associated with HR_aft, HR_5min, and ΔHR. In contrast, smaller, lipid-poor subfractions (HDL-7 to HDL-10) were associated with higher heart rates and a less favorable post-exercise response. Total HDL-C and subclass-level concentrations showed no significant association. These findings suggest that HDL particle size distribution may provide exploratory insight into exercise-related cardiovascular responses beyond conventional lipid metrics. Although limited by the use of a submaximal field test and manual heart rate assessment, these results support further investigation of HDL subfraction profiling in relation to post-exercise heart rate dynamics. Full article