Search Results (3,160)

Microplastics (MPs) and nanoplastics (NPs) have emerged as pervasive pollutants across different aquatic systems on a global basis, yet integrated assessments linking wastewater, riverine, and marine environments remain scarce. The present study provides the first comprehensive evaluation of MPs in three interconnected aquatic matrices of Northern Greece, namely surface seawater from the Thermaic Gulf, surface freshwater from the Axios River, and influent and effluent wastewaters from the Thessaloniki WWTP (Sindos). During two sampling periods spanning late 2023 and spring 2024, suspected MPs were isolated, morphologically classified by stereomicroscopy, and chemically characterized through pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). MPs were ubiquitously detected in all substrates, exhibiting distinct spatial and compositional patterns. Seawater samples displayed moderate concentrations (1.5–4.8 items m⁻³) dominated by fibers and fragments, while riverine samples contained slightly higher levels (0.5–2.5 items m⁻³), enriched in fibrous forms and polyolefins (PE, PP). Wastewater influents showed the highest MP abundance (78–200 items L⁻¹; 155.6–392.3 µg L⁻¹), decreasing significantly in effluents (11–44 items L⁻¹; 27.8–74.3 µg L⁻¹), corresponding to a removal efficiency of 81–87.5%, being the first indicative removal efficiencies in a Greek WWTP. Among the different polymers detected, polyethylene, polypropylene, and poly(ethylene terephthalate) were identified as the most prevalent polymers across all matrices. Interestingly, a shift toward smaller size classes (125–500 µm) in effluents indicated in-plant fragmentation processes, while increased concentrations during December coincided with increased rainfall, highlighting the influence of hydrological conditions on MP fluxes. The combined morphological and polymer-specific approach provides a holistic zunderstanding of MP transport from inland to marine systems, establishing essential baseline data for Mediterranean environments and reinforcing the need for integrated monitoring and mitigation strategies. Full article

Human health is profoundly influenced by external factors, with stress being a primary contributor. In this context, the digestive system is particularly susceptible. The prevalence of diseases affecting the small intestine and colon is increasing. Consequently, insoluble plant fibers, such as cellulose and hemicellulose, play a crucial role in promoting intestinal transit and maintaining colon health. Lettuce is a widely consumed leafy vegetable with high nutritional value and has been intensively studied through hydroponic cultivation. This study aims to optimize the cultivation conditions and freeze-drying process of Lugano and Carmesi lettuce varieties (Lactuca sativa L.) by identifying the optimal growth conditions, freeze-drying duration, and sample surface area in order to achieve an optimal percentage of insoluble fibers. Carmesi and Lugano varieties were selected based on their contrasting growth characteristics and leaf morphology, allowing to assess whether treatments and processing conditions have consistent effects on different types of lettuce. The optimal freeze-drying parameters were determined to include a 48 h freeze-drying period, a maximum sample surface area of 144 cm², and growth under combined conditions of supplementary oxygenation and LED light exposure. The optimal fiber composition, cellulose (21.61%), hemicellulose (11.84%) and lignin (1.36%), was found for the Lugano variety, which exhibited lower lignin and higher cellulose contents than the Carmesi variety. The quantification of hemicellulose, cellulose and lignin was performed using the well-known NDF, ADF and ADL methods. Therefore, optimized freeze-dried lettuce powder, particularly from the Lugano variety, presents a high-value functional ingredient for enriching foods and developing nutritional supplements aimed at digestive health. Full article

In this paper, a highly ductile polyvinyl alcohol fiber engineered cementitious composite (PVA-ECC) was developed by replacing quartz sand (QS) with tuff stone powder (TP) at different replacement ratios of 20%, 40%, 60%, 80%, and 100%. The resulting mechanical properties and drying shrinkage were determined for the developed ECC. Qualitative and quantitative analyses of hydration products, pore structure, and micro-morphology of ECC were conducted by X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, pore size and porosity, and scanning electron microscopic imaging. The influencing mechanism of tuff stone powder content on ECC performance was also studied at a micro level. It was found that with the increase in the replacement ratio of tuff stone powder, the ultimate tensile strain and tensile peak stress of ECC all exhibited an increasing trend, which declined afterward. The variation in compressive and flexural strengths also showed a similar pattern. When the replacement ratio of tuff stone powder was 40%, the ultimate tensile strain, peak tensile stress, flexural strength, and compressive strength were higher than the control group by 15.1%, 4.7%, 16.3%, and 10.7%, respectively. When the content of tuff stone powder did not exceed 80%, it could fill the internal pores of the ECC matrix, which reduced harmful pores. With the increase in tuff stone powder content, calcite content increases gradually while the Ca(OH)₂ amount decreases. It can be seen that tuff stone powder can improve ECC hydration products. However, incorporating tuff stone powder does not produce new hydration products. Incorporating tuff stone powder increased the drying shrinkage of ECC, and the value of drying shrinkage increased with the increase in the replacement ratio of tuff stone powder. Full article

Spunbonding drafters play a decisive role in determining fiber attenuation, morphology, and final nonwoven quality; however, their internal airflow behavior remains poorly characterized due to limited physical accessibility and historically empirical design practices. This work employs high-fidelity computational fluid dynamics (CFD) to systematically resolve the airflow field inside a laboratory-scale drafter and to quantify the impact of geometry on fiber drawing conditions. The simulations reveal a previously unreported “braking effect,” where adverse flow structures reduce effective shear drag, limit drawability, and increase the likelihood of fiber breakage. Parametric virtual experimentation across seven geometric variables demonstrates that the drafter configuration strongly governs shear distribution, flow uniformity, and energy consumption. Using a performance-oriented optimization framework, three key processing objectives were targeted: (i) maximizing shear drag to promote stable fiber attenuation, (ii) improving axial drawing uniformity, and (iii) minimizing pressurized-air demand. CFD-guided design modifications—including controlled widening, tailored wall divergence and convergence, and an extensible lower section—were implemented and subsequently validated using a newly constructed prototype. Experimental measurements on polypropylene (PP) and high-density polyethylene (HDPE) fibers confirm substantial reductions in fiber breakage and improvements in drawing stability, thereby demonstrating the effectiveness of simulation-driven process optimization in spunbonding equipment design. Full article

This study examines the through-thickness microstructure and crystallographic texture evolution in friction-stir-welded (FSWed) AA5052-H32 and AA6061-T651 aluminum alloys using a tri-flats threaded pin tool. Optical microscopy and electron backscatter diffraction (EBSD) were employed to characterize grain morphology, boundary misorientation, and texture components across the weld thickness. Both alloys exhibited progressive grain refinement and increased high-angle grain boundary fractions from the top to the bottom of the stir zone due to combined thermal and strain gradients. The FSWed AA5052 displayed dominant {111}<110> and Y + γ fiber components at the upper and mid regions, whereas AA6061 showed more randomized textures. At the bottom region, both alloys developed rotated Goss {011}<01-1> and weak A ({112}<110>) and α fiber components. These results clarify how alloy strengthening mechanisms—solid-solution versus precipitation hardening—govern texture evolution under different strain-path and heat input conditions. The findings contribute to optimizing process parameters and material selection for structural-scale FSW aluminum joints in industrial applications such as bridge decks, transportation panels, and marine structures. Full article

Background/Objectives: The search for biomarkers of cognition has garnered significant interest over the past decade, owing to their objective nature, in contrast to the currently available cognition screening tools, which are based on subjective measures. Retina imaging is used in this field because its tissue is considered as an extension of the brain’s vascular and neural structures, reflecting overall brain health. In cognitive disorders, early detection and intervention are essential for achieving the best possible outcomes. To evaluate the physiological correlates of cognitive function in healthy young adults by assessing retinal structures as a non-invasive biomarker of cognitive health. Methods: Eighty healthy young adults participated in this study. Optical Coherence Tomography (OCT) was used to measure retinal morphology, including macular thickness, volume, and retinal nerve fiber layer thickness; then, OCT results were correlated with cognitive assessments using the Montreal Cognitive Assessment (MoCA). Results: Participants with mild cognitive impairment exhibited thinner macular thickness and lower macular volume (p < 0.05, p < 0.001) than participants with normal cognitive function. We also found that macular thickness is positively associated with cognitive function in healthy adults (p < 0.001). The RNFL was found to be normal in all groups, despite changes in macular thickness, indicating that cognitive function in normal individuals depends on macular changes rather than the optic nerve. Conclusions: Macular OCT, which is a cost-effective and widely available tool, can be used to screen for mild cognitive impairment. A clinical trial is recommended to validate these findings and to generate guidelines for assessing cognitive physiology through the retina. Full article

Lake Kotokel is one of the largest lakes along the eastern shore of Lake Baikal. Increasing anthropogenic pressure combined with climate variability led to a sharp decline in its ecological condition, culminating in an outbreak of Gaff disease in 2009. Moreover, Lake Kotokel may serve as a source of pollutants to Lake Baikal due to its hydrological connection via a system of rivers. In light of these factors, ongoing research seeks to identify the drivers of ecological degradation in the lake ecosystem and provide a comprehensive assessment of its current environmental status and potential adverse processes. In this study, we report, for the first time, the occurrence of microplastic particles in the surface water and sediments of Lake Kotokel. Mean microplastic concentrations were 0.59 ± 0.25 items/m³ in water and 280 ± 162 items/kg dry weight in sediments, with corresponding average microplastic masses of 2.6 ± 1.4 μg/m³ in water and 1.33 ± 1.21 mg/kg dry weight in sediments. In surface waters, microplastic were predominantly 1–3 mm in size, whereas sediments were dominated by 0.1–1 mm particles. Fibers were the most abundant morphological form, comprising 79.5% and 82.8% of particles in water and sediments, respectively. Five polymer types were identified, with polyethylene terephthalate being the most prevalent. Based on particle abundance and polymer composition, the ecological risk of microplastic in Lake Kotokel was assessed as low to moderate. Full article

Adhesive joint failure remains a critical limitation in the manufacturing of large wind turbine blades, where reliable and reproducible surface preparation methods are required at an industrial scale. This study systematically evaluates the effect of peel ply-induced surface morphology and chemistry on the adhesion performance of glass fiber-reinforced polymer (GFRP) laminates, explicitly examining the relationship between wettability and bonding strength. Five surface conditions were generated during vacuum-assisted resin infusion using different commercial and proprietary peel plies and a smooth mold surface. Despite significant differences in contact angle and surface energy, lap shear testing revealed no significant relationship between wettability and joint strength. Instead, surface roughness-driven mechanical interlocking and adhesive–substrate compatibility dominated performance. Compared to the smooth mold surface, twill-type peel ply–modified adherends increased shear strength by up to 3.9×, while other commercial types of peel-plies presented strength improvements between 2.7 and 3.3×. More compatible adhesive–polymer resin systems exhibited a combination of cohesive and adhesive failures, with no clear dependence on surface roughness. In contrast, when the adhesive is less compatible with the substrate, surface roughness significantly affects the adhesive response, with adhesive failure predominating. The adhesive application temperature showed no measurable effect for practical industrial use. These findings demonstrate that wettability alone is not a reliable predictor of adhesion performance for this class of substrates and confirm peel ply surface modification as a robust, scalable solution for industrial wind blade bonding. Full article

Wood polymer composite (WPC), composed of polymer matrices reinforced with natural fibers, is increasingly used in structural and non-structural applications due to its sustainability and performance. Although teak and rice husk are common natural reinforcements, the use of oil palm empty fruit bunches (OPEFB) remains underexplored despite their abundance as agricultural waste. This study investigates the potential of OPEFB as an alternative reinforcement for recycled polyethylene-based WPC containing 20 wt% fiber and compares its morphology and performance with teak and rice husk. Compositional analysis shows that OPEFB exhibits lignin and cellulose contents as well as crystallinity comparable to teak, while exceeding rice husk in several structural parameters. These characteristics contribute to the highest tensile strength observed among the composites (37.45 MPa). Although its Shore D hardness is the lowest (58.8), the value remains within the acceptable range for construction applications. Combined with its favorable production costs, OPEFB emerges as a viable, resource-efficient alternative to conventional natural fibers, expanding the options for sustainable WPC development. Full article

Various methods for classifying and evaluating the shape, size, and surface texture of sand particles are examined, highlighting their impact on concrete mixture properties. This study emphasizes the role of particle morphology in determining concrete workability and segregation, particularly in glass-fiber-reinforced (GRC) thin-layer concrete for building facade panels. The effects of different aggregate types on concrete workability and segregation are analyzed, showing that aggregates with spherical particles and a lower elongation index improve mixture consistency and reduce segregation. Three types of fine aggregates were used (instead of quartz sand in the mixtures, natural sand and granite screenings were chosen, which would be a sustainable alternative to quartz sand), and thin-layer glass-fiber-reinforced concrete using aggregates of different shapes was characterized by layering the mixture. The workability and segregation of fine-grained fiberglass-reinforced concrete mixtures depend on the aggregate particles’ shape. Up to 50% of quartz sand can be replaced with granite siftings or natural sand, as measured by the segregation index, as calculated according to the method proposed in this paper. Increasing the amount of natural sand from 10% to 50% also increases the segregation index from 1.9 to 2.6, and when using granite sifting aggregates, it rises from 2.6 to 3.5. Aggregates with spherical particles are more suitable for this thin-layer GRC concrete, if we examine the consistency parameters of fresh concrete and the possibilities of working with it in real production conditions. Full article

Microplastics are increasingly recognized as contaminants of emerging concern in wastewater systems, where treatment plants act both as sinks and as point sources. However, Central Asian wastewater infrastructures are under-represented in the literature, and global syntheses are hindered by strong methodological heterogeneity (sampling regimes, size cut-offs, QA/QC). This PRISMA-guided critical review compiles and harmonizes data from 63 WWTP studies worldwide (402 matrix-stage observations), including the few available case studies from Kazakhstan and neighboring countries, to benchmark Central Asian plants against a global envelope and identify methodological and infrastructure gaps. Globally, influent concentrations cluster around a median ≈65 particles/L, while final/tertiary effluents show a median ≈2.2 particles/L. Median removal efficiency is 85.5% for secondary and 95.0% for tertiary/advanced trains, with ≈10³–10⁵ particles/kg DW typically retained in sludge. Across influent, effluent and sludge, fibers and fragments of PE, PP and PET dominate polymer morphology patterns, with similar PET/PE/PP signatures also reported in downstream river water. Central Asian influents fall within global interquartile ranges, but secondary-only facilities tend to yield effluents in the upper half of the global distribution. Overall, the review provides a first integrated, methodologically explicit assessment of WWTP microplastics in Central Asia and underscores the need for protocol harmonization, longitudinal monitoring, and targeted upgrades of polishing steps and sludge management in arid hydrosystems. Full article

This work focused on the development of eco-friendly bio-composites based on polylactic acid (PLA) and sugarcane bagasse (SCB) as a natural fiber from Moroccan vegetable waste. First, the fiber surface was treated with an alkaline solution to remove non-cellulosic components. Then, the composite materials with various amounts of treated sugarcane bagasse (TSCB) were fabricated using two routes, melt processing and solvent casting. The primary objective was to achieve high fiber dispersion/distribution and homogeneous bio-composites. The dispersion properties were analyzed using scanning electron microscopy (SEM). Subsequently, the thermal, mechanical, and melt shear rheological properties of the obtained PLA-based bio-composites were investigated. Through a comparative approach between the dispersion state of fillers with extrusion/injection molding and solvent casting method, the work aimed to identify the most suitable processing route for producing PLA-based composites with optimal dispersion, improved thermal stability, and mechanical reinforcement. The results support the potential of TSCB fibers as an effective bio-based additive for PLA filament production, paving the way for the development of eco-friendly and high-performance materials designed for 3D printing applications. Since the solvent-based route did not allow further improvement and presents clear limitations for large-scale or industrial implementation, the transition toward 3D printing became a natural progression in this work. Material extrusion offers several decisive advantages, notably the ability to preserve the original morphology of the fibers due to the moderate thermo-mechanical stresses involved, and the possibility of manufacturing complex geometries that cannot be obtained through conventional injection molding. Although some printing defects may occur during layer deposition, the mechanical properties obtained through 3D printing remain promising and demonstrate the relevance of this approach. Full article

Electrospinning of poly(lactic acid) (PLA) commonly relies on toxic organic solvents, which limit its sustainability and biomedical applicability. In this work, a green electrospinning process was developed using dimethyl carbonate (DMC), a biodegradable and low-toxicity solvent, combined with acetone as a volatile co-solvent to promote efficient jet solidification. Three commercial PLA grades were evaluated for solubility and spinnability, and PLA 4043D was identified as the most suitable for DMC and acetone systems. The electrospinning parameters, including solvent ratio, flow rate, and applied voltage, were systematically optimized to achieve stable jet formation and uniform fiber morphology. Under optimized conditions, the process produced continuous, bead-free nanofibers with a mean diameter of ~1 µm and uniform nanoscale surface porosity resulting from differential solvent evaporation. The resulting fibers were characterized in terms of morphology, structure, thermal behavior, and mechanical performance, confirming increased amorphous content, high porosity (about 78%), and tensile strength of ~3 MPa for the selected electrospinning condition. This study demonstrates that DMC-based solvent systems enable a sustainable and potentially biocompatible route, considering the lower toxicity of the solvents employed, offering a green alternative to conventional toxic processes for the fabrication of medical scaffolds. Full article

Araucaria angustifolia produces seeds known as Pinhão, which are valued for their nutritional composition and potential use in functional foods. This study investigated the production and characterization of spray-dried Pinhão extracts using inulin (E1) and polydextrose (E2) as carrier agents. The formulations were assessed for physicochemical composition, physical properties, rehydration behavior, morphology, phenolic profile, and mineral content. Spray drying resulted in yields of 67.7% (E1) and 60.6% (E2). E1 exhibited higher carbohydrate (37.02 g/100 g) and fiber contents (34.11 g/100 g), as well as lower moisture (1.35 g/100 g) and water activity (0.16), yielding powders with greater stability and lighter color. E2 demonstrated a superior rehydration performance, with higher wettability and dispersibility, attributed to the amorphous and hydrophilic nature of polydextrose. The matrix formed by inulin and polydextrose during spray drying was equally effective in preserving the low contents of phenolic compounds, demonstrating the suitability of the technique for stabilizing these heat-sensitive bioactive compounds. Only very low levels of phenolic compounds were detected in both samples, which is consistent with the naturally low phenolic content of the Pinhão almond. Mineral analysis showed greater calcium and magnesium retention in E1, whereas E2 contained higher levels of potassium, phosphorus, iron, and zinc. Overall, inulin enhanced powder stability and compactness, while polydextrose improved rehydration behavior and mineral preservation, supporting the potential application of Pinhão extract powders in functional and health-oriented food products. Full article

Worldwide, carbon fiber (CF) demand has been rising over the last decade, which contrasts with the fact that up to 30–50% of composite materials in aircraft production are scrapped. This situation highlights the increasing need for recycling methods to reduce fabrication costs and global warming potential. Emerging technologies focus on recovering long CFs, as they represent the most valuable form but are also the most difficult to reclaim using conventional recycling methods. Hydrothermal treatments offer a promising alternative to valorize this waste by decomposing the polymer matrix under subcritical and supercritical conditions without significantly damaging the fibers. Water, isopropanol, and mixtures of water/isopropanol or water/acetone were tested as solvents, with and without the addition of zinc chloride (ZnCl₂) as a homogeneous catalyst. The influence of temperature, pressure, and solvent composition on resin degradation was evaluated. In this work, degradation rates of up to 92% were achieved at 415 °C, 233 bar, 120 min, 5 wt.% IPA, and ZnCl₂ 0.1 M. It should be noted that ZnCl₂ caused reactor corrosion. Furthermore, the recovered fibers retained their morphology, including the sizing layer, and showed mechanical properties similar to the original material, while a small H₂-rich gaseous fraction was generated as a byproduct of the hydrothermal degradation. Using water–isopropanol solutions resulted in the reactor being significantly cleaner than when using water alone, which can be advantageous for future scale-up and for reducing maintenance requirements. These results confirm the potential of hydrothermal processing as an efficient and selective method for the recycling and valorization of carbon-fiber-reinforced composites from the aeronautical industry. Full article