Search Results (365)

This study examines whether twisted tape inserts in a pipe system can reduce pipe erosion under a liquid–solid flow regime. Three different twisted tape configurations were designed using 3D printing technology: tapes with one twist, four twists, and four twists with perforations. Experiments were performed using a PVC pipe with a carbon steel plate as the material under investigation. Slurries of water and silica sand were prepared with varying sand concentrations—1%, 3%, and 5%—to induce different erosion rates. The experimental results were backed by Computational Fluid Dynamics (CFD) using the discrete phase model (DPM) to predict particle flow and erosion attributes. Erosion trends were also tested through mass loss and paint loss tests. The analysis outcomes demonstrated that the one-twist, four-twist, and perforated four-twist tapes reduced the erosion rate by 18%, 39%, and 45%, respectively. Among the different configurations, the four-twist tape with holes reduced erosion the most. These results suggest that twisted tape inserts can control erosion, thereby increasing the service life of pipes that handle abrasive flows. Full article

Hard anodic oxide coatings on aluminium have long been used to enhance surface functionality. However, increasing industrial demands are driving the need for coatings with superior hardness, wear resistance, corrosion resistance and self-lubricating properties. Due to their porous structure, anodic oxide coatings can be modified by incorporating various nanoparticles. The properties of the modified coatings depend on both the type of nanoparticles used and the method employed to incorporate them. In this study, anodic oxide coatings were produced using direct and duplex methods on a semi-industrial scale to enable process control and potential industrial implementation. The coatings were modified with hard (Al₂O₃) and soft (CaCO₃, PTFE) nanoparticles in order to customise their functional properties. Their microstructure and chemical composition were characterised by SEM and TEM. Their microhardness, abrasion resistance and electrochemical behaviour were also evaluated. Among the tested production methods and methods for modifying nanoparticles, the duplex process incorporating Al₂O₃ particles proved to be the most promising. Its optimisation resulted in coatings with a microhardness of 430 HV0.05 and a mass loss of 9.4 mg after the Taber abrasion test, demonstrating the potential of this approach for industrial applications. Full article

Fly ash–based geopolymers have emerged as a promising alternative to ordinary Portland cement, offering high mechanical strength and reduced environmental footprint. However, they are often limited by significant shrinkage and strength degradation when subjected to elevated temperatures. To enhance their thermomechanical performance and thermal stability, this study investigates the effects of mix proportioning parameters, alkali activator type, and thermal shock on performance deterioration. Compressive strength was evaluated for sodium- and potassium-activated fly ash geopolymer composites as a function of alkaline activator (AA) ratios, both under ambient curing and after exposure to the ISO 834 standard fire curve for 1 and 2 h. Volume change, mass loss, and density variation were analysed to interpret mechanical behaviour and relate it to structural transformations, while XRF, XRD, SEM, and particle size distribution were employed for material characterisation. Results indicate that rapid temperature changes, whether from thermal shock or high fire-heating rates, induced notable additional thermal degradation. Sodium activation achieved the highest compressive strength retention of 145% at one hour of firing, while potassium activation showed superior thermal stability with delayed densification, reaching 154% strength retention at two hours. Furthermore, SiO₂/M₂O ratio exerted the strongest influence on both mechanical and thermomechanical performance. Overall, the findings highlight that the activator type, SiO₂/M₂O ratio, and rapid temperature changes collectively exert strong control over the thermomechanical and thermophysical response of fly ash geopolymers at elevated temperatures. Full article

Sulfidized nano zero-valent iron (S-nZVI) particles are known to stimulate the reductive removal of various oxyanions due to enhanced electron selectivity and electron conductivity between the Fe(0) core and the target compound. Sulfidation creates a number of reactive sulfur species, the role of which has not yet been investigated in the context of S-nZVI. In this study, we investigated the contribution of reactive sulfur species to Se(VI) reduction by S-nZVI at different molar S/Fe ratios (0, 0.1 and 0.6) and Se(VI) concentrations (0, 5 and 50 mg L⁻¹). In the presence of S-nZVI, the rate of reduction was accelerated by a factor of up to ten. X-ray Absorption Near-Edge Structure (XANES) spectroscopy and surface-sensitive X-ray photoelectron spectroscopy (XPS) identified Se(0) as the predominant reduction product (~90%). The reduction reaction was accompanied by a loss of FeS and the formation of surface-bound Fe(II) polysulfide (FeSx) and S(0) species. Likewise, wet chemical extraction techniques suggested a direct involvement of acid volatile sulfide (AVS) species (surface-bound FeS) in the reduction of Se(IV) to Se(0) and formation of S(0). Mass balance estimates reveal that between 9 and 15% of the conversion of Se(0) originates from oxidation of FeS to FeSx. From these findings, we propose that surface-bound Fe sulfide species are important but previously overlooked reactants contributing to the reduction of oxyanions associated with S-nZVI particles, as well as in natural environments undergoing sulfidation reactions. Full article

The study examines how crushed and sieved concrete rubble—recycled concrete fines (RCF) and the ways of their reactivity activation—affect processing, mix design, and properties of cement-based concrete. Based on the relationship to mass loss during crushing, the compressive strength of the concrete fines processed from rubble was initially determined. The morphology of the particles as well as the chemical and mineralogical composition of RCF were ascertained using XRD, SEM, and EDS characterization tests. Certain RCF surface area (fineness) and type of treatment are associated with specific pozzolanic activity of RCF. Using the approaches of factorial experimental design, tests were planned by varying six factors: RCF specific surface area, RCF content, thermal treatment temperature of RCF, cement content, superplasticizer dosage, and hardening accelerator (Na₂SiF₆) content in concrete containing RCF. Statistical processing of the research results data provided adequate polynomial regression models for the water demand of the concrete and the compressive strength of hardened concrete at 7 and 28 days. The models were quantitatively analyzed to evaluate the influence of the studied factors on the output parameters and to rank them according to their impact. The greatest increase in water demand was attributed to cement content change, in particular above 400 kg/m³, and to RCF content. It was established that the addition of a superplasticizer compensated for additional water demand and the reduction in compressive strength caused by partial replacement of cement with RCF. Increasing the specific surface area of RCF up to a specific surface area of 250 m²/kg improved compressive strength but further grinding caused strength reduction due to increased water demand. The positive effect of the superplasticizer on RCF-modified concrete strength was enhanced by the introduction of a chemical activator (hardening accelerator) and thermal treatment of RCF. The obtained models of water demand and compressive strength of concrete with RCF can be applied for the optimization of the mix design. This paper proposes a method of mix design and provides an example of calculation. Full article

Microplastic pollution is a growing global environmental and public health concern, driven by the increasing production and use of plastics. Due to their ubiquitous presence in the environment, humans and animals may be exposed to micro- and nanoplastics via several possible routes. For micro- and nanoplastics, the development of standardized and validated methods remains an important area of progress to support human health risk assessments. In order to monitor micro/nanoplastics’ occurrence in organisms and the environment, it is necessary to develop accurate and reliable methods to quantify and characterize micro/nanoplastics from various biological and environmental matrices. In this study, an analytical, multi-platform approach was established to characterize and quantify polystyrene nanoplastics in biological samples through a combination of sample pre-concentration, asymmetric flow field-flow fractionation, ultraviolet–visible light, dynamic light scattering detectors and pyrolysis–gas chromatography–mass spectroscopy. Several digestion methods on various rodent tissues were tested and modified, and these led to the development of tissue-specific protocols to maximize yield. These digestion protocols were then combined with a new method of concentrating and retaining plastics to prevent the loss of submicron particles. For identification and quantification, known amounts of polystyrene nanoplastics were spiked into rodent tissues (intestine, kidney and liver). This was followed up by a mouse in vivo study consisting of a single dose of PS-NPs, followed by tissue collection, digestion and analysis. Polystyrene particles were detected in the liver and kidney, but not reliably in the intestinal tissues. Full article

Mechanical forces, chemical and electrochemical reactions, and environmental variables can all lead to surface degradation of parts. Composite coatings can be applied to these materials to enhance their surface characteristics. Recently, nickel-based composite coatings have gained greater attention because of their remarkable wear resistance. The efficiency, precision, and affordability of this process make it a popular method. In addition, electroplating nickel-based composites offers a more environmentally friendly alternative to traditional dangerous coatings such as hard chrome. Tribological and wear characteristics are highly dependent on several variables, such as particle parameters, deposition energy, fluid dynamics, and bath composition. Mass loss, coefficient of friction, hardness, and roughness are quantitative properties that provide useful information for coating optimization and selection. Under optimized electrodeposition conditions, the Ni-SiC-graphite coatings achieved a 57% reduction in surface roughness (Ra), a 38% increase in microhardness (HV), and a 25% reduction in wear rate (Ws) compared to pure Ni coatings, demonstrating significant improvements in tribological performance. Overall, the incorporation of SiC nanoparticles was found to consistently improve microhardness while graphite or MoS₂ reduces friction. Differences in wear rate among studies appear to result from variations in current density, particle size, or test conditions. Furthermore, researchers run tribology studies and calculate the volume percentage using a variety of techniques, but they fall short in providing a sufficient description of the interface. This work primarily contributes to identifying gaps in tribological research. With this knowledge and a better understanding of electrodeposition parameters, researchers and engineers can improve the lifespan and performance of coatings by tailoring them to specific applications. Full article

In January 2025, multiple wildfires erupted across the Los Angeles region, fueled by prolonged dry conditions and intense Santa Ana winds. Southern California has faced increasingly frequent and severe wildfires in recent years, driven by prolonged drought, high temperatures, and the expanding wildland–urban interface. These fires have caused major loss of life, extensive property damage, mass evacuations, and severe air-quality decline in this densely populated, high-risk region. This study integrates passive and active satellite observations to characterize the spatiotemporal and vertical distribution of wildfire emissions and assesses their impact on air quality. TROPOMI (Sentinel-5P) and the recently launched TEMPO geostationary instrument provide hourly high temporal-resolution mapping of trace gases, including nitrogen dioxide (NO₂), carbon monoxide (CO), formaldehyde (HCHO), and aerosols. Vertical column densities of NO₂ and HCHO reached 40 and 25 Pmolec/cm², respectively, representing more than a 250% increase compared to background climatological levels in fire-affected zones. TEMPO’s unique high-frequency observations captured strong diurnal variability and secondary photochemical production, offering unprecedented insights into plume evolution on sub-daily scales. ATLID (EarthCARE) lidar profiling identified smoke layers concentrated between 1 and 3 km altitude, with optical properties characteristic of fresh biomass burning and depolarization ratios indicating mixed particle morphology. Vertical profiling capability was critical for distinguishing transported smoke from boundary-layer pollution and assessing radiative impacts. These findings highlight the value of combined passive–active satellite measurements in capturing wildfire plumes and the need for integrated monitoring as wildfire risk grows under climate change. Full article

This study evaluated the effects of glycerol–citric acid (Gly-CA) modification and polyurethane (PU) adhesive concentration on the properties and termite resistance of rattan skin-based particleboards. Rattan skin particles were modified with 0%, 20%, and 40% Gly-CA and bonded using 6% or 12% PU adhesive. Gly-CA modification significantly improved dimensional stability, reducing water absorption and thickness swelling to about 35–40% and 4–6%, respectively, at 40% Gly-CA with 12% PU. However, excessive modification decreased mechanical strength due to over-crosslinking, while 20% Gly-CA provided the best balance between strength and stability. FTIR analysis confirmed ester and urethane bond formation, while thermogravimetric results showed enhanced thermal stability with increasing Gly-CA content (T_max up to 356.8 °C). Field tests conducted over 98 days revealed a substantial improvement in durability, with termite-induced mass loss decreasing from about 28% in untreated boards to below 8% in Gly-CA–modified samples. From this study, the combination of 40% Gly-CA modification and 12% PU adhesive produced particleboards with improved dimensional and thermal stability, as well as durability against termites. These findings highlight glycerol–citric acid bio-modification as a sustainable and effective strategy for developing durable eco-friendly rattan skin-based composites. Full article

This study focused on the preparation of microcapsules that simulate adipose tissue cells via complex coacervation, followed by the formation of block-like fat analogue products through gelation. The results indicated that microcapsules obtained by encapsulating coconut oil with soy protein isolate (SPI) and sodium alginate (SA) through a complex coacervation process could serve as effective fat substitutes in meat products. When the mass ratio of SPI to SA was 3:1, the core-to-wall mass ratio was 1:1, and the total wall material concentration was 3% (w/v), the oil loading rate of the microcapsules reached 39.17%. The particle size of the oil-loaded microcapsules was mainly distributed between 40–180 μm, which was comparable to the size of fat cells in animal adipose tissue. Microcapsules (50%, w/w) were mixed with a 5% (w/v) curdlan dispersion and heated at 95 °C for 60 min to form fat analogues. The fat analogues demonstrated significantly reduced cooking loss, enhanced textural rigidity, and superior chew resistance, achieving performance metrics comparable to those of natural adipose tissue. This dual-phase strategy—combining interfacial engineering of lipid microcapsules with polysaccharide-mediated gelation—provides a promising approach for developing sustainable, plant-based fat alternatives in meat product reformulation. The methodology not only addresses texture and flavour challenges in fat replacement but also enables precise control over lipid content, supporting applications in healthier food systems. Full article

Cavitation resistance in hydraulic machinery requires the turbine and water pump surface to simultaneously possess high hardness and plasticity. To keep the FCC structure of the Al_xCoCrFeNi alloy matrix and introduce the particle strengthening effects, the suitable weight content of Cr₂AlC particles was calculated and added into Al_0.3CoCrFeNi powders. Due to the decomposition of Cr₂AlC during laser cladding, the microhardness of Al_0.3CoCrFeNi was enhanced by Al atoms and the eutectic-like Cr₇C₃ structure. In comparison with 5.81 GPa of Al_0.3CoCrFeNi coating measured by nanoindentation, the values of the eutectic-like structure and the matrix were measured as 7.76 GPa and 5.93 GPa in 12 wt.% Cr₂AlC/Al_0.3CoCrFeNi coating. Attributed to the pinning effect of hard Cr₇C₃ and high plastic matrix, the mass loss was reduced from 7.25 × 10⁻⁴ g/mm² for Al_0.3CoCrFeNi coating to 1.91 × 10⁻⁴ g/mm² Cr₂AlC/Al_0.3CoCrFeNi coating with a ratio of 73.8%. Full article

This study addresses the drawbacks of traditional dispersed fire retardants—such as anisotropy, reduced strength, and poor filler impregnability—by developing in situ-formed hybrid epoxy composites. The materials, based on diglycidyl ether of bisphenol A and triethylenetetramine, were modified with a solution of zinc sulfate heptahydrate in orthophosphoric acid. This approach yielded near-spherical microparticles (6–16 µm) within the polymer matrix. The scientific novelty lies in investigating how such in situ particle formation affects material properties. The modification significantly enhanced fire resistance: char residue increased 1.7–2.2-fold, while total heat release, peak heat release rate, and smoke release were reduced by up to 60.5%, 40.2%, and 70%, respectively. The observed increase in the mass loss rate suggests that accelerated thermal-oxidative degradation promotes char formation. These findings, supported by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy data, demonstrate the efficacy of the in situ strategy for creating high-performance, fire-safe epoxy composites. Full article

Fractured lost circulation remains a major drilling challenge due to low compatibility between conventional plugging materials and fractures. By utilizing thermosetting resin emulsification and high-temperature crosslinking coalescence, this study developed a temperature-activated nanomaterial enhanced liquid–solid phase transition plugging emulsion. The system adapts to varying fracture apertures, forming plugging particles with a broad size distribution and high strength upon thermal activation. The structural characteristics, mechanical properties, and fracture-plugging performance of the plugging particles were systematically investigated. Results demonstrate that the optimized system, comprising 8 wt.% emulsifier, 0.16 wt.% dispersant, 0.4 wt.% crosslinker, 0.4 wt.% viscosifier, 70 wt.% distilled water, and 2 wt.% nano-silica (all percentages relative to epoxy resin content), can produce particles with a size of 1–5 mm at formation temperatures of 80–120 °C. After 16 h of thermal aging at 180 °C, the particles exhibited excellent thermal stability and compressive strength, with D(90) degradation rates of 3.07–5.41%, and mass loss of 0.63–3.40% under 60 MPa. The system exhibits excellent injectability and drilling fluid compatibility, forming rough-surfaced particles for stable bridging. Microscopic analysis confirmed full curing in 140–180 min. Notably, it sealed 1–5 mm fractures with 10 MPa pressure, enabling adaptive plugging for unknown fracture apertures. Full article

Rotary tillage blades, as critical components of soil tillage machinery, encounter significant challenges in mountainous agricultural operations, where excessive wear and high energy consumption are persistent issues. To address these problems, this study proposes an integrated strategy combining structural optimization with surface reinforcement. A blade–soil interaction model based on Smoothed Particle Hydrodynamics (SPH) was developed to optimize blade geometry, reducing power consumption to 0.106 kW with a simulation error of only 2.83%. In parallel, Fe60–WC composite coatings containing 30%, 35%, and 40% WC were fabricated on 65Mn substrates using laser cladding. Microstructural analysis revealed significant grain refinement with increasing WC content, while tribological tests showed that the 35% WC coating blades exhibited superior wear resistance, with a mass loss of 1.9 mg, and a relatively low friction coefficient of 0.362. Field trials further confirmed that the blades resulted in a 45.75% reduction in average wear, after structural enhancement and the application of the optimized coating, with a measured loss of 2.259 g compared to the uncoated blades. These findings demonstrate the synergistic benefits of structural optimization and advanced surface engineering, providing an effective pathway to improve the durability and efficiency of rotary tillage blades in demanding field conditions. Full article

Conventional polishing of glass substrates often results in surface scratches caused by passivated abrasive particles, leading to defects and reduced yield. To overcome this limitation, an iron-bonded wheel with free abrasive grains was proposed in ELID (Electrolytic In-process Dressing) grinding. The polishing mechanisms were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and micro-indentation. Polishing efficiency was assessed via mass loss measurements, surface quality was characterized by atomic force microscopy (AFM), and optical transmittance was evaluated using a transmittance meter. Results indicate that the proposed wheel does not contain fixed abrasive particles but generates α-Fe₂O₃ particles during polishing, effectively preventing surface scratches and achieving superior surface quality. The polishing efficiency ranged from 0.02 to 1.6 μm/min, with a resulting surface roughness of 2.1 nm. Furthermore, the glass substrates exhibited higher transmittance compared to those polished using conventional methods, contributing to improved display performance and brightness. This polishing technology demonstrates significant potential for applications in the display industry. Full article