Search Results (500)

With the progressive decline of tailpipe emissions, non-exhaust sources such as brake wear are becoming an increasingly important contributor to traffic-related particulate matter in urban environments. In this context, improving real-world characterization of brake wear particles is essential for air-pollution assessment, source apportionment, and the development of cleaner and more sustainable road transport systems. Here, we investigated the emissions levels, particle size distribution and elemental composition of particles released during harsh real-world braking events by a single light-duty vehicle braking system equipped with an original manufacturer (OEM) non-asbestos organic (NAO) pad formulation. Using a direct on-vehicle sampling system combined with real-time particle sizing and high-resolution microscopy, we observed that particle emissions remained close to background levels at speeds up to 100 km/h, but rose sharply at 120 km/h, reaching 3.7 × 10⁷ #/cm³ in the 8–10 nm size range. This increase suggests that higher speeds are associated with elevated particle emissions, likely due to the higher braking temperatures reached at increased vehicle speeds. The emitted particles were mainly spherical agglomerates rich in iron, titanium, barium, zirconium, and sulphur, consistent with NAO pad formulations. Our results show that the investigated NAO pad system can deteriorate under thermal stress, potentially leading to higher levels of nanoparticle emissions compared to low-metallic or semi-metallic pads investigated under similar conditions. These findings provide real-world evidence relevant to urban air quality research, support the refinement of non-exhaust emissions inventories, and highlight the importance of thermally resilient friction-material formulations for mitigating residual particulate emissions in increasingly cleaner transport systems. Full article

Microplastics (MPs), i.e., plastic particles <5 mm, and nanoplastics (NPs), i.e., plastic particles <1 µm, are widespread in the environment. MPs and NPs (MNPs) have also been detected in human tissues. Environmental MNPs exhibit diverse physicochemical properties such as size, shape, and surface degradation. However, most experimental studies have used pristine MNPs, which poorly represent real-world conditions, and only a limited number of studies have focused on preparing environmentally relevant MNPs. Therefore, we focused on the key physicochemical properties of MNPs, particularly their shape, size, and surface degradation, using polyvinyl chloride (PVC) as the model polymer. In this study, fragment and spherical PVC-MNPs were utilized, and surface degradation was introduced through exposure to vacuum ultraviolet (VUV) radiation at a wavelength of 172 nm. Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) analysis revealed the formation of additional carbonyl groups after VUV exposure. We investigated the cytotoxic effects of the degraded and non-degraded PVC-MNPs on A549, Caco-2, and THP-1 cells. The results indicated that the degraded PVC-MNP-treated groups induced higher cytotoxic effects than those in the non-degraded groups. Notably, the degraded PVC-NPs induced stronger cytotoxicity than the degraded PVC-MPs. These findings highlight the potential health risks associated with environmental MNPs. Full article

This study presents the characterization of the aerodynamic forces and moments acting on irregular particles of prescribed sphericity, generated through truncated spherical harmonic expansions and immersed in a uniform flow at intermediate Reynolds numbers (1 ≤ Re ≤ 200). Particle-resolved direct numerical simulations are conducted using the commercial solver ANSYS Fluent to quantify the statistical behavior of drag, transverse lift, and transverse torque coefficients, along with the corresponding force and moment components, as a function of Reynolds number. Deviations from spherical geometry are shown to induce persistent flow asymmetries, leading to finite transverse lift and torque components even under uniform inflow conditions, effects that cannot be captured by models based on dynamically equivalent spheres. For a sphericity of 0.93, represented by six particle realizations, irregular particles exhibit mean drag values approximately 10% higher than those of spheres with the same equivalent diameter. In addition, both the magnitude and the statistical characteristics of the aerodynamic coefficients are strongly modulated by the combined effects of particle shape irregularity and flow regime. These results provide new insight into the role of geometric complexity in fluid–particle interactions and represent a step forward toward improved predictive capability beyond conventional spherical and quasi-spherical approximations. Furthermore, the present findings provide a physically grounded basis for the development of fluid–particle interaction models for irregular particles, suitable for implementation within Euler–Lagrange simulations of turbulent dispersed flows. Full article

Cinnamomum zeylanicum (C. zeylanicum) is rich in bioactives, such as cinnamaldehyde and phenols, which are susceptible to thermal degradation, volatilisation, and oxidative deterioration during processing and storage, thereby reducing chemical stability and limiting bioavailability. Encapsulation using lecithin and chitosan-based systems mitigates these instabilities by forming a protective barrier against oxygen, light, and heat while enhancing structural stability. In this study, freeze-dried extracts of C. zeylanicum were encapsulated into lecithin-based primary liposomes (PL) and chitosan-coated secondary liposomes (CH/L). The coating of liposomes with chitosan improves the liposome stability, mucoadhesion, and provides protection in the gastric pH while facilitating electrostatic bonding with the biological membrane. The high compatibility and low toxicity of chitosan also make it a suitable carrier in food and nutraceutical applications. The formed liposomes were characterised for particle size, polydispersity index, zeta potential, encapsulation efficiency (EE), and storage stability over 8 weeks. CH/L showed superior EE (89.027%) compared to the PL (84.154%; p < 0.05). The particle size, polydispersity index, and zeta potential of the cinnamon-loaded lecithin-based primary liposome (CZ-PL) upon formation were 161.93 nm, 0.13, and −37.597 mV. In comparison, those of the cinnamon-loaded chitosan-coated liposomes (CZ-CH/L) were 591.7 nm, 0.27, and +28.17 mV. The particle size of CZ-PL and CZ-CH/L was 175.90 and 588.60 nm after 8 weeks of storage. The TEM confirmed the spherical morphology of the liposomes. The differential scanning calorimetry analysis demonstrated the disappearance of the characteristic cinnamon melting peak and shifts in liposomal transition temperatures, confirming successful encapsulation. FTIR analysis showed reduction or disappearance of characteristic cinnamon fingerprint peaks and slight band shifts, indicating successful encapsulation and non-covalent interactions, including hydrogen bonding and electrostatic effects, within the liposomal systems. These findings imply that lecithin-based and chitosan-coated liposomes could be employed to successfully carry C. zeylanicum bioactives. Full article

Currently, the resource wastage and safety hazards caused by fruit and vegetable spoilage are becoming increasingly prominent. Developing green, efficient, and non-toxic novel preservation materials has emerged as a hot spot in fruit and vegetable research. Based on this, this study utilized pomegranate peel as a raw material to prepare spherical multifunctional carbon dots (P-CDs) with an average particle size of 1.98 ± 0.58 nm through a one-step hydrothermal reaction. Subsequently, P-CDs were co-incorporated with L-cysteine (L-Cys) into a polyvinyl alcohol (PVA) and chitosan (CS) matrix to construct a novel composite coating material with combined antibacterial, antioxidant, and preservation functions. Experimental results demonstrate that P-CDs exhibit outstanding antioxidant activity and antibacterial performance. Compared to PVA/CS film, the P-CDs/L-Cys/PVA/CS film exhibited a 6.55 MPa increase in tensile strength and significantly enhanced thermal stability. Furthermore, the incorporation of P-CDs and L-Cys markedly boosted the PVA/CS film’s antioxidant activity (97% for ABTS; 85.69% for DPPH), antibacterial performance, and ultraviolet (UV) shielding capability. Coating cherry tomatoes with the P-CDs/L-cysteine/PVA/CS composite extended their shelf life by 6 days. This composite coating material exhibits preliminary biocompatibility and eco-friendly properties, aligning with green sustainable development needs and offering a novel potential solution for food preservation technology, while its practical applicability to food safety requires further comprehensive verification. Full article

Precise control over the physicochemical and biological properties of colloidal particles is essential for the rational design of functional soft materials. In this work, we report a simple and scalable strategy for generating modular dendron particles (MDPs) through the self-assembly of fully characterized small-molecule Bis-MPA dendrons that act as programmable molecular building blocks for colloidal particle formation. By systematically varying three structural domains—the inner functionality, methylene spacer length, and outer connector—we achieve tunable formation of MDPs ranging from nano- to microscale dimensions. Upon solvent evaporation under mild drying conditions, pre-assembled MDPs act as structure-directing seeds that guide the emergence of hierarchical surface morphologies with spiky, scaly, or spherical protrusions, depending on dendron architecture. Importantly, these assemblies exhibit good biocompatibility toward non-tumoral bronchial epithelial (NL-20) cells while displaying selective cytotoxicity toward Neuro-2a neuroblastoma cells, demonstrating that dendron molecular architecture alone can govern particle size, morphology, and biological response without external drug loading. Collectively, these findings highlight modular Bis-MPA dendrons as versatile building blocks for directing particle size, morphology, and biological response through controlled self-assembly and evaporation-driven structuring. Full article

To achieve precise control over droplet size and generation frequency in the granulation process of HNS-IV, this study introduces a novel droplet granulation strategy that utilizes pulsed air-jet shearing technology. This approach enables independent and precise regulation of droplet injection frequency (fg) and volume (V) through systematic adjustments of air pressure (P), frequency (fp), duty cycle (η), and liquid flow rate (Q). By controlling the suspension flow rate (Q), we successfully achieved primary particle size control, obtaining median particle sizes (D50) of 375.84 μm, 444.45 μm, and 504.22 μm in ascending order. Furthermore, we systematically investigated the influence of calcium alginate (CA) concentration on both the sphericity of the resultant particles and the thermal decomposition characteristics of HNS microspheres. Our findings demonstrate that while increased CA content enhances particle sphericity, it simultaneously affects the thermal decomposition behavior of the microspheres. The proposed pulsed air-jet shearing method offers significant advantages by significantly reducing the accumulation of volatile organic solvents typical of liquid–liquid biphasic systems. Furthermore, the residual non-toxic aqueous solutions can be easily managed, establishing a greener, safer, and highly controllable approach for HNS-IV granulation. This methodology presents a valuable reference for achieving precise and controllable granulation of various energetic materials. Full article

Calculation of heat transfer in granular materials is an important task for many applications, from thermal management in electronics to exploring celestial soils. Usually, an effective thermal-conductivity model is employed to predict heat flux in unstructured granular media, such as a packed bed. However, a more advanced approach, the discrete element method (DEM), can capture the complex effects of mechanical loading and material mixtures on thermal transport coefficients, which traditional models struggle with. Pivotal for this approach is knowing the heat transfer coefficient between two adjacent particles. Currently, in most DEM-capable software, only particles in direct surface contact are considered to have non-zero heat conduction. We propose considering particles that are close to each other but don’t have a contact area with a non-zero surface area. We perform numerical modeling of the conductive heat transfer coefficient between equal spherical particles separated by media, assuming the fluid’s thermal conductivity is at least an order of magnitude lower. We use numerical solutions of differential equations to account for both thermal resistance within particles and through the gap between them. We found a simple generalized correlation for the heat transfer coefficient between particles and a general formula for the angular distribution of heat flux density across the particle surface. By employing a non-dimensional approach, the obtained formulas are constructed using non-dimensional parameters: the ratio of the particle’s thermal conductivity to that of the medium, and the ratio of the gap width between particles to their radius. The resulting formula is simple and convenient for DEM heat transfer calculations in packed and fluidized beds. Full article

The transport mechanism of non-spherical particles in complex pipelines, such as right-angle elbows, remains insufficiently understood, posing challenges to the efficiency optimization of industrial systems like deep-sea mining. This study investigates the fundamental mechanisms governing the upward transport of 1–15 mm non-spherical particles in a 100 mm right-angle bend by integrating Particle Image Velocimetry (PIV) experiments with coupled computational fluid dynamics and discrete element method (CFD-DEM) simulations. We systematically quantify the effects of key factors—flow velocity, particle size distribution, and shape factor (ranging from 0.4 to 1)—on flow asymmetry, particle dynamics, and transport efficiency. The results reveal a pronounced flow asymmetry, where the outer-side peak velocity is approximately twice that of the inner side, accompanied by a persistent separation vortex. Crucially, transport efficiency is governed by particle interactions: wide-grading blends achieve up to 12% higher conveying speed than narrow fractions at high flow rates. While spherical particles (shape factor, SF = 1) attain the highest axial velocity, particles with SF ≥ 0.8 are identified as optimal, maintaining moderate rotation, concentrating in the central high-speed zone, and thereby combining high transport velocity with minimal wall contact. These findings elucidate the underlying particle–fluid interactions in bends and provide a quantitative basis for optimizing particle morphology in industrial hydraulic transport systems. Full article

The accumulation of copper smelting slags generated by non-ferrous metallurgy represents both an environmental challenge and a potential source of technogenic raw materials for value-added products. In this study, the feasibility of producing magnesia–quartz proppants from secondary copper smelting slag formed after the pyrometallurgical extraction of iron and zinc was investigated. The slag, primarily composed of oxides of the SiO₂–CaO–Al₂O₃–MgO system, was processed by centrifugal melt granulation to obtain spherical granules suitable for proppant applications. The initial granules exhibited an amorphous glassy structure and insufficient mechanical strength, with up to 70% of particles destroyed under a pressure of 34.5 MPa. Controlled heat treatment within the temperature range of 300–1000 °C induced crystallization of silicate and aluminosilicate phases, leading to a significant improvement in mechanical performance. Optimal properties were achieved after holding at 800 °C for 60 min, where the fraction of crushed granules decreased to 10%, meeting the requirements of GOST R 54571-2011. The influence of MgO content on microstructure and strength was also examined. Increasing the MgO concentration from 5 to 16 wt.% resulted in grain refinement and improved crushing resistance, reducing the fraction of destroyed granules to 3%. To enhance chemical durability, a phenol–formaldehyde protective coating was applied, decreasing proppant solubility in a hydrochloric–hydrofluoric acid mixture from 19% to 2%. These results demonstrate that secondary copper smelting slag can serve as a promising raw material for producing standard-compliant proppants while contributing to the efficient utilization of metallurgical waste. Full article

This study analyzes the hydrodynamic characteristics of a short magnetorheological squeeze film damper, with emphasis on the fluid microstructure responsible for generating damping forces. The magnetorheological fluid contains non-Brownian spherical particles suspended in a non-magnetic Newtonian fluid. When exposed to a magnetic field, these particles form chain-like structures that restrict fluid motion. In this context, the Mason number characterizes the fluid microstructure and establishes the ratio of viscous to magnetic forces. The mathematical model for solving the flow field, which depends on the continuity and momentum laws, the Bingham rheological model, and boundary conditions at the interfaces, is solved analytically. The Reynolds equation determines the fluid pressure distribution and follows the Sommerfeld boundary condition. Mass imbalance induces chaotic rotor motion, resulting in lateral vibrations. As the journal squeezes the fluid, positive pressure develops, generating damping forces that dissipate vibration energy. The results in this research show that the Mason number significantly affects fluid pressure, which increases as magnetostatic forces exceed viscous forces. This increase in pressure produces damping forces that reduce rotor displacement. Additionally, both radial and tangential forces increase with particle volume fraction, in contrast to classical Newtonian behavior. These findings are relevant to the handling of magnetorheological fluids in vibration control mechanisms. Full article

This study numerically investigates the effects of red blood cell (RBC) volume fraction (hematocrit) and RBC diameter on cell distribution, cell-free layer (CFL) thickness and pressure drop in a microchannel with sudden expansion. Hematocrit levels of 0.2, 0.3, 0.4 and 0.5, together with RBC diameters of 4, 8 and 11 µm, are considered, where deviations from the physiological diameter of 8 μm represent pathological conditions. An Euler–Euler approach is employed to model the multiphase flow, treating RBCs as rigid spherical particles, while the non-Newtonian viscosity of blood is represented using a modified Carreau–Yasuda model. The numerical predictions are validated against existing experimental and numerical data. The effect of volumetric flow rate on RBC distribution is found to be limited; therefore, a representative flow rate of 100 μL/min is adopted for the subsequent analysis. The results show that RBC migration and the resulting cell distribution are strongly governed by RBC size and hematocrit. The pressure drop is primarily influenced by hematocrit, while the effect of RBC size is relatively weak. A minimum value for pressure drop is observed at a hematocrit of 0.3, indicating an optimal hematocrit level for minimizing flow resistance. A parabolic correlation is proposed for predicting the pressure drop as a function of hematocrit, with a maximum relative error of 1.13%. This study contributes to the understanding of pathological RBC size variations and their impact on microscale hemodynamics. Full article

Microplastics (MPs) are widespread worldwide and have become a significant environmental problem due to their durability and the large quantities that enter ecosystems. As the global spread of microplastic pollution continues, the Armenian gull (Larus armenicus) in the Lake Van Basin has emerged as an important bioindicator. This study highlights the widespread impact of human-generated waste on natural habitats by detecting the presence of microplastics in gull feces using a non-invasive, polymer-supported method. Methods: The study was conducted between 10 May 2024 and 26 April 2025. A total of 480 fecal samples were analyzed from four stations with different characteristics and exposed to various anthropogenic effects. Instead of individual-level statistical inference, we performed temporal comparisons descriptively at the composite level. Results: We categorized suspected MPs by type, shape, size, and color, using FTIR to confirm the polymer identity of a representative subset (>300 µm; ~20%) and SEM–EDX to examine particle surfaces. A total of 8197 MP particles were observed in the feces collected from the stations. The most frequently observed MP type, size, shape and color were fiber (32.6%), 100–300 µm (30.8%), spherical (29.2%) and brown (18.4%), respectively. The chemical structures of all examined MPs were polyethylene (PE) (42.6%), polystyrene (PS) (28.38%) and polyethylene terephthalate (PET) (8.5%). SEM-EDX confirmed that the microplastics are polymers by showing their degraded surface and carbon/oxygen ratio. Conclusions: Identifying polymer species in ingested plastics is valuable for future studies, as the results can be used to assess the relationship between microplastics. Full article

Macadamia husks are an underutilized by-product of nut processing and a rich source of phenolic compounds with strong antioxidant activity. However, their instability during processing, storage, and gastrointestinal digestion limits their application in food systems. This study aimed to encapsulate macadamia husk phenolic-rich extract (MHPE) in liposomes to improve stability, enable controlled release, and assess cytotoxicity for functional food applications. MHPE was encapsulated in soy lecithin liposomes using high-shear mixing followed by high-pressure homogenisation. Liposomes were characterized by particle size, polydispersity index (PDI), ζ-potential, encapsulation efficiency, and morphology. Cytotoxicity was evaluated using Caco-2 cells, and phenolic release was assessed under simulated gastrointestinal conditions. MHPE-loaded liposomes exhibited nano-sized particles (77–78 nm), low PDI (0.21), and high negative ζ-potential (−43.11 to −47.01 mV) during two months of storage at 4 °C. Transmission electron microscopy confirmed predominantly spherical vesicles with sizes consistent with dynamic light scattering measurements. Encapsulation efficiency remained high (81.50% initially; 73.60% after 28 days). Both free and extract-loaded liposomes were non-cytotoxic to Caco-2 cells. Encapsulated MHPE showed slower phenolic release compared with the free extract. Overall, liposomal encapsulation effectively enhanced the stability and controlled release of macadamia husk phenolics, supporting their potential use as functional food and nutraceutical ingredients. Full article

Numerical simulations of (1) two aerosol types such as organic carbon (i.e., spherical) and dust (i.e., non-spherical) particles, and (2) their mixtures are carried out. Optical and microphysical parameters of these aerosols in our simulations are provided by MERRA-2 (Modern-Era Retrospective Analysis for Research and Applications, version 2). The inversion routine is performed with TiARA (Tikhonov Advanced Regularization Algorithm) using the Lorenz–Mie (i.e., spherical) light-scattering model in unsupervised and automated, i.e., autonomous mode. The results of our numerical simulations show that the accuracy of the inversion results for the aerosol mixtures from synthetic optical data perturbed by ±10% random error is comparable to the accuracy observed for the inversion results of the “pure” spherical particles. In particular, the retrieval uncertainties of effective radius, and number, surface-area, and volume concentrations of these mixtures are ±30%, ±10%, between −50% and +100% and ±30%, respectively. However, we need to apply a modified version of the gradient correlation method (GCM) to stabilize the inversion results. The results of this study will form the baseline for future work, where we plan to apply TiARA to optical data products obtained from real lidar observations in the framework of the SCC (Single Calculus Chain) of EARLINET (European Aerosol Research Lidar Network). Full article