Search Results (1,049)

The evaluation of the interfacial shear strength between sand and steel materials plays a fundamental role in the design of geotechnical foundations and structures. However, testing equipment cannot consider the dual effects of particle size and steel roughness on a uniform stress state. In this study, a novel torsion shear apparatus was designed that can measure arbitrary displacement within the interface. On this basis, the influence of the sand particle size and contact surface roughness on interface shear behavior was studied, and the sand–steel interface mechanical responses, including stress state, sample deformation, and friction properties, were evaluated. The results of the torsional interface shear test (TIST) were compared with those of the conventional direct interface shear test (DIST). The results indicate that the shear strength of rough interfaces exceeds that of smooth interfaces but remains below the shear strength observed in pure soil shear tests. Moreover, a critical value of relative roughness exists, beyond which the peak shear stress or friction angle does not significantly increase. Despite variations in the sand grain sizes used in the tests, the corresponding friction angles were approximately equal. In pure soil shear tests, the friction angle was positively correlated with grain size, indicating that grain size directly affects the friction angle in pure soil shear. Additionally, the normalized interface friction angles obtained from the torsional interface shear tests showed good agreement with those derived from interface direct shear tests. Full article

This study systematically investigates the influence of Zr additions (0–0.24 wt.%) on the microstructure evolution and mechanical properties of Al–4.0Cu–0.5Mg–0.5Zn–0.5Mn–0.4Ag alloys under peak-aged conditions. Alloys were subjected to homogenization (420 °C/8 h + 510 °C/16 h), solution treatment (510 °C/1.5 h), and aging (190 °C/3 h). Microstructural characterization via OM, SEM, EBSD, and TEM revealed that Zr refines grains and enhances recrystallization resistance through coherent Al₃Zr precipitates, which pin grain boundaries and dislocations. However, excessive Zr (0.24 wt.%) induces heterogeneous grain size distribution and significant Schmid factor variations, promoting stress concentration and premature intergranular cracking. Crucially, Al₃Zr particles act as heterogeneous nucleation sites for Ω-phase precipitates, accelerating their nucleation near grain boundaries, refining precipitates, and narrowing precipitate-free zones (PFZs). Mechanical testing demonstrated that the Al–4.0Cu–0.5Mg–0.5Zn–0.5Mn–0.4Ag alloy exhibits optimal properties: peak tensile strength of 368.8 MPa and 79.8% tensile strength retention at 200 °C. These improvements are attributed to synergistic microstructural modifications driven by controlled Zr addition, establishing Al–4.0Cu–0.5Mg–0.5Zn–0.5Mn–0.4Ag–0.16Zr as a promising candidate for high-temperature aerospace applications. Full article

The impact of milling process parameters on the physicochemical properties of waste plum stones was investigated to enable their further utilization as a functional material. The experiments were conducted using a planetary ball mill, with variations in milling duration (1–3 h), the ball-to-powder ratio (bpr) (10:1 and 20:1), and the rotation speed (250 and 500 rpm). Transformations of material in a function of process parameters were assessed by XRD, FTIR, and SEM analysis, revealing differences in particle size distribution, functional group composition, and surface morphology. Optimization of milling process parameters was focused on promoting fine particle formation and surface activation without causing significant material degradation. The best result was achieved with the PS-M10 sample, processed at a speed of 500 rpm and a bpr of 20:1 during a short milling time of 1 h. The milled sample demonstrated promising potential for further applications, particularly for heavy metal ion (Pb²⁺ and Cu²⁺) removal from aqueous solutions through adsorption. Full article

This research investigates the interaction between a flexible thin-walled hemisphere and the surrounding wake at $R{e}_D=2\times {10}^5$ acting as a simplified model of a flexible surface protuberance immersed within a turbulent boundary layer (BL). A flexible model and a rigid model, both 100 mm in diameter, are experimentally tested to observe and contrast the flow variation between a rigid structure and a freely deforming structure. Two experiments were conducted. To capture fluid flow behaviour, stereo particle image velocimetry (SPIV) was used. To capture structural deformation of the model, digital image correlation (DIC) was utilised. Experimental testing was conducted non-simultaneously. From the experimental testing, it was observed that the flexible model experienced a leading edge (LE) deformation at $29°$ of the altitude angle ($\theta$), showing an average deformation of $2.11$ mm. All regions of the structure experienced non-zero distortion due to the incoming wind load. This was similar to behaviour observed in previous literature. This caused a modulation in the wake region, giving a parabolic wake velocity contour to form about $\theta \approx 20°$. A velocity inflection point is observed for the flexible model at an average of $\theta =23.39°$ within the wake. This inflection region extends surrounding the area of maximum structural deflection up to $\theta \approx 40°$. This indicates that the deflection across the LE centreline has a direct interaction with location and size of the near wake. Turbulent kinetic energy (TKE) in the wake was observed to drop with the introduction of the flexible model, with a lower dissipation rate observable. This is indicative of energy transfer from the flow to the structure, allowing deformation. The maximum region of TKE coincides with the recirculation vortex core region, which was shown to move from $z/D=$ 0.19 to $z/D=$ 0.35 for the rigid and flexible models, respectively. The results indicate that, with the Reynolds number tested, the rigid behaviour is in line with previous literature trends. The flexibility of the model, therefore, highly influences the wake region, with general shape deformation causing a decrease in near wake TKE and change in wake shape and recirculation core location. Full article

This article examines the influence of micro- and nanoscale calcium carbonate (CaCO₃) fillers on the dielectric behavior and aging resistance of polyvinyl chloride (PVC)-based composites. PVC films containing varying CaCO₃ contents (0%, 2.5%, 5%, and 7.5% by weight) were subjected to accelerated aging through prolonged ultraviolet (UV) exposure and thermal stress for up to 1248 h. The evolution of dielectric properties was characterized by impedance spectroscopy, while structural modifications were analyzed using Fourier-transform infrared (FTIR) spectroscopy. Additionally, changes in surface morphology, internal homogeneity (related to particle size, shape, and distribution), and chemical composition were investigated using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDX), to evaluate the effects of irradiation and variations in the material’s surface composition and morphology. The results reveal a significant correlation between filler concentration and dielectric stability, highlighting the potential of CaCO₃ reinforcement to improve the long-term reliability of polymeric insulating materials. The results further highlight that beyond the amount of filler used, the fine-scale feature of CaCO₃, particularly its particle size and how well it is dispersed, has a significant impact on how the material responds to aging and maintains its dielectric properties. Full article

This study presents the first investigation into the distribution of microplastics (MPs) in Sasebo City, Japan, using principal component analysis (PCA) in conjunction with water flow velocity and salinity variables. The mean MP abundance was 82.4 ± 47.7 items/m³ (SSB1–SSB4), showing no significant difference among sampling points. The fragment-to-fiber ratio was 76:24, and polypropylene and polyethylene (each 41%) were the main polymers. Fragment abundance increased with decreasing particle size, while fibers were rare below 700 μm. PCA indicated distinct MP polymer and shape distributions corresponding to stagnant water (SSB1), high-flow conditions (SSB2 and SSB3), and seawater (SSB4). Based on the literature, the study area represents a case of a small-scale aquatic system with limited anthropogenic influence due to moderate population, short river length, efficient effluent discharge, minimal industry, good water quality, and the absence of significant spatial variation in MP abundance. The infrequent precipitation during the sampling event supports the findings of the present study as a reliable baseline for objectively assessing MP contamination. Compared to aquatic systems of varying scales and anthropogenic influence, this baseline is applicable to both small-scale and large-scale aquatic systems with significant influences. This will serve as a valuable reference for future MP studies across diverse freshwater environments. Full article

Tungsten powder/polytetrafluoroethylene (W/PTFE) composites have the potential to replace traditional metallic materials as casings for controllable power warheads. Under explosive loading, they generate high-density and relatively uniformly distributed metal powder particles, thereby enhancing close-range impact effects while reducing collateral damage. To characterize the material’s response under impact loading, plate impact tests were conducted to investigate the effects of tungsten content (70 wt%, 80 wt%, and 90 wt%) and tungsten particle size (200 μm, 400 μm, and 600 μm) on the impact behavior of the composites. The free surface velocity histories of the target plates were measured using a 37 mm single-stage light gas gun and a full-fiber laser interferometer (DISAR), enabling the determination of the shock velocity–particle velocity relationship to establish the equation of state. Experimental data show a linear relationship between shock velocity and particle velocity, with the 80 wt% and 90 wt% composites exhibiting similar shock velocities. The fitted slope increases from 2.792 to 2.957 as the tungsten mass fraction rises from 70 wt% to 90 wt%. With particle size increasing from 200 μm to 600 μm, the slope decreases from 3.204 to 2.756, while c₀ increases from 224.7 to 633.3. Comparison of the Hugoniot pressure curves of different specimens indicated that tungsten content significantly affects the impact behavior, whereas variations in tungsten particle size have a negligible influence on the Hugoniot pressure. A high tungsten content with small particle size (e.g., 90 wt% with ~200 μm) improves the overall compressive properties of composite materials. Based on the experimental results, a mesoscale finite element model consistent with the tests was developed. The overall error between the numerical simulations and experimental results was less than 5% under various conditions, thereby validating the accuracy of the model. Numerical simulations revealed the coupling mechanism between tungsten particle plastic deformation and matrix flow. The strong rarefaction unloading effect initiated at the composite’s free surface caused matrix spallation and jetting. Multiple wave systems were generated at the composite–copper interface, whose interference and coupling ultimately resulted in a nearly uniform macroscopic pressure field. Full article

In this study, we investigate the dominant electromagnetic wave absorption mechanism–ferromagnetic resonance (FMR) loss versus quarter-wave cancellation in a novel PVDF-based polymer composite embedded with carbonaceous nanostructures incorporating FeCoCr ternary alloy. The majority of the nanoparticles are embedded at the terminal ends of the carbon nanotubes, while a small fraction exists as isolated core–shell, carbon-coated spherical particles. Overall, the synthesized material predominantly exhibits a nanotubular carbon morphology. High-resolution transmission electron microscopy (HRTEM) confirms that the encapsulated nanoparticles are quasi-spherical in shape, with an average size ranging from approximately 25 to 40 nm. The polymeric composite was synthesized via solution casting, ensuring homogenous dispersion of filler constituent. Electromagnetic interference (EMI) shielding performance and reflection loss characteristics were evaluated in the X-band frequency range. Experimental results reveal a significant reflection loss exceeding −20 dB at a matching thickness of 2.5 mm, with peak absorption shifting across frequencies with thickness variation. The comparative analysis, supported by quarter-wave theory and FMR resonance conditions, indicates that the absorption mechanism transitions between magnetic resonance and interference-based cancellation depending on the material configuration and thickness. This work provides experimental validation of loss mechanism dominance in magnetic alloy/polymer composites and proposes design principles for tailoring broadband microwave absorbers. Full article

Utilizing a coupled Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) approach, this study constructs a comprehensive three-dimensional numerical model to simulate particle migration dynamics within rough artificial fractures subjected to the high-energy impact of water inrush. The model explicitly incorporates key governing factors, including intricate fracture wall geometry characterized by the joint roughness coefficient (JRC) and aperture variation, hydraulic pressure gradients representative of inrush events, and polydisperse sand particle sizes. Sophisticated simulations track the complete mobilization, subsequent acceleration, and sustained transport of sand particles driven by the powerful high-pressure flow. The results demonstrate that particle migration trajectories undergo a distinct three-phase kinetic evolution: initial acceleration, intermediate coordination, and final attenuation. This evolution is critically governed by the complex interplay of hydrodynamic shear stress exerted by the fluid flow, frictional resistance at the fracture walls, and dynamic interactions (collisions, contacts) between individual particles. Sensitivity analyses reveal that parameters like fracture roughness exert significant nonlinear control on transport efficiency, with an identified optimal JRC range (14–16) promoting the most effective particle transit. Hydraulic pressure and mean aperture size also exhibit strong, nonlinear regulatory influences. Particle transport manifests through characteristic collective migration patterns, including “overall bulk progression”, processes of “fragmentation followed by reaggregation”, and distinctive “center-stretch-edge-retention” formation. Simultaneously, specific behaviors for individual particles are categorized as navigating the “main shear channel”, experiencing “boundary-disturbance drift”, or becoming trapped as “wall-adhered obstructed” particles. Crucially, a robust multivariate regression model is formulated, integrating these key parameter effects, to quantitatively predict the critical migration time required for 80% of the total particle mass to transit the fracture. This investigation provides fundamental mechanistic insights into the particle–fluid dynamics underpinning hazardous water–sand inrush phenomena, offering valuable theoretical underpinnings for risk assessment and mitigation strategies in deep underground engineering operations. Full article

The widespread application of granite manufactured sand (GS) concrete in pavement engineering is limited by issues such as suboptimal particle size distribution and an unclear optimal rock powder content. Furthermore, research on the long-term evolution of the skid resistance characteristics of GS concrete remains relatively scarce. This knowledge gap makes it difficult to accurately assess the skid resistance performance of GS concrete in practical engineering applications, thereby compromising traffic safety. To address this research gap, this study utilized a self-developed indoor abrasion tester for pavement concrete to assess the skid resistance of GS concrete. Three-dimensional laser scanning was employed to acquire the concrete’s surface texture parameters. Using the friction coefficient and texture parameters as skid resistance evaluation indicators, and combining these with changes in the concrete’s surface morphology, the study explores how effective sand content, stone powder content, and fine aggregate lithology affect the long-term skid resistance of GS concrete pavements and reveals the evolution trends of their long-term skid resistance. Research results show that as the number of wear cycles increases, low and high effective sand content affect the surface friction coefficient of specimens in opposite ways. Specimens with 95% effective sand content exhibit superior skid resistance. Stone powder content influences the friction coefficient in three distinct variation patterns, showing no clear overall trend. Nevertheless, specimens with 5% stone powder content demonstrate better skid resistance. Among different fine aggregate lithologies, GS yields a higher friction coefficient than river sand (RS), while limestone manufactured sand (LS) shows significant friction coefficient fluctuations across different wear cycles. Adding stone powder substantially enhances mortar strength and delays groove collapse edge formation. Moreover, higher effective sand content and proper stone powder content mitigate bleeding, thereby improving mortar performance. Full article

Microplastic pollution in the Chesapeake Bay is of critical concern as estuaries serve as habitats and nurseries for diverse aquatic organisms and offer vital ecological services. However, quantitative analysis of microplastics, especially those smaller than 300 µm, in the natural aquatic environment is very challenging due to a lack of efficient sampling methods. This study takes a novel approach to quantify the abundance, size distribution, and morphological characteristics of microplastics, as small as 20 µm, in the surface waters of the Chesapeake Bay. Water samples (10 L) were collected monthly from July 2023 to October 2023 at four locations along the Chesapeake Bay. The samples were digested with a 10% potassium hydroxide solution and subjected to density separation using sodium chloride (ρ = 1.2 g/cc). Microplastic particles were examined using a Shimadzu AIM–9000 FTIR microscope for enumeration and chemical identification. Overall, the mean microplastic concentration observed was 766.16 ± 302.59 MP/L, significantly higher than previously estimated in the Chesapeake Bay. Microplastic abundance exhibited a significant (p = 0.02) spatial variation across the four sampling locations. Most abundant were particles less than 100 µm (60.65%), followed by particles between 100 µm and 300 µm (23.19%), and particles exceeding 300 µm (16.16%). Morphological analysis identified fragments as the dominant shape (86.02%), followed by fibers (11.87%), and beads (2.10%). This study underscores the importance of standard and efficient sampling methods in microplastics research. By sampling microplastics as small as 20 µm, this research demonstrated that the abundance of microplastics in the Chesapeake Bay is significantly higher than previously estimated and dominated by smaller–sized particles. These small microplastics are more likely to enter the food web where human exposure may occur. Therefore, microplastic pollution in the Chesapeake Bay ecosystem has the potential to impose environmental and public health risks. Full article

With the rising trend of health-conscious consumers, demand for gluten-free alternatives is increasing, and rice flour is a promising gluten-free alternative for chicken batter. This study examines the effects of particle size variations in Baromi-2 rice flour on batter rheology and the quality attributes of deep-fat fried chicken. Baromi-2 is a rice variety specifically developed to meet the demands of the modern food processing industry, especially for applications requiring dry milling. Five particle sizes (60, 100, 120, 160, and 180 mesh) were evaluated on the basis of their physicochemical properties, including water-holding capacity (WHC), amylose content, and damaged starch levels. Batter consistency was assessed and frying performance was analyzed with regard to coating pickup, cooking loss, moisture content, crust color, and textural attributes. Results demonstrated that finer particle sizes (e.g., 180 mesh) exhibited high WHC and batter viscosity, resulting in reduced flowability and enhanced adhesion. These properties contributed to high coating pickup, improved moisture retention, and reduced cooking loss during frying. Fried chicken prepared with finer particles showed soft textures, great cohesiveness, and light crust colors with high lightness (L*) and reduced redness (a*) and yellowness (b*), producing a visually appealing product. By contrast, larger particle sizes (e.g., 60 mesh) resulted in low viscosity, uneven coatings, and high cooking loss. This study highlights the critical role of rice flour particle size in optimizing batter functionality and improving the quality of fried foods. Furthermore, these findings suggest the potential to bridge the gap between consumer demand for healthier fried foods and the food industry’s demands. Full article

The structural features of Sb–doped (Ti,Zr)NiSn and (Ti,Zr,Hf)NiSn half-Heusler (HH) thermoelectrics have been identified down to the atomic scale using a combination of transmission electron microscopy (TEM) techniques. TEM sheds light on the morphology, phases present, size distributions and elemental variations between the two samples. Both materials consist of the HH phase, at both micro- and nanoscale levels, and comprise particles with two size ranges, 115 and 223 nm, on average, for large HH particles and 4–17 nm for nanoparticles for both materials. Hf incorporation in the HH lattice brought upon significant elemental fluctuations, manifested in chemical profiles and lattice parameter variations measured by post-experimental image analysis. The increased elemental variations induced by Hf substitution significantly contributed to the low thermal conductivity values and high power factor, leading to an enhanced figure of merit of 0.76 at 762 K for (Ti,Zr,Hf)NiSn, demonstrating the capability of TEM to confirm the structural features that are responsible for improved TE performance. Full article

Recently, there has been a growing interest in using agricultural and forestry residues to cultivate Flammulina filiformis. However, there is limited research on cultivating F. filiformis with soybean straw as a substrate. This study systematically optimized the cultivation formula for F. filiformis using soybean straw as the raw substrate and explored the effects of the water content, carbon-to-nitrogen ratio (C/N ratio), substrate particle size, and substrate loading on its growth and development. By replacing corncob, wheat bran, and soybean hulls with soybean straw and increasing the proportion of rice bran, the cultivation formula for growing F. filiformis was optimized. We found that the maximum fruiting body yield of 405 g (330 g dry substrate per bottle) and a biological efficiency of 122.73% were achieved using a substrate mixture of 25% soybean straw, 20% corncob, 20% cottonseed hull, 25% rice bran, 8% wheat bran, 1% CaCO₃, and 1% shellfish powder. The yield and biological efficiency of fruiting bodies cultivated on the substrate containing 25% soybean straw did not show significant differences compared to the control group. However, the cultivation formula containing 25% soybean straw yielded F. filiformis with significantly higher levels of amino acids, essential amino acids, and fat. These findings suggest that the 25% soybean straw substrate formulation can serve as a viable alternative to the control formulation for the cultivation of F. filiformis, although variations in the nutritional composition exist. Based on this optimized formula, an optimal biological efficiency can be achieved with a substrate-to-water ratio of 1:1.7, a wet substrate loading amount of 940 g (in a 1250 mL cultivation bottle), and a soybean straw particle size range of 6–8 mm. The optimal C/N ratio for cultivating F. filiformis using soybean straw ranges from 27:1 to 32:1. Additionally, orthogonal experiments revealed that the nitrogen content significantly affected the fruiting body yield, stipe length, and stipe diameter, while the water content mainly affected the pileus diameter, pileus thickness, and number of fruit bodies. Under defined conditions (dry substrate loading volume of 337 g (in a 1250 mL cultivation bottle), a substrate-to-water ratio of 1:1.6, and a C/N ratio of 26:1), the maximum yield and biological efficiency per bottle reached 395 g and 117.21%, respectively. Our findings indicate that the F. filiformis cultivation using soybean straw as the raw substrate exhibits a promising performance and extensive application potential. Full article

Portable near-infrared reflectance spectroscopy (NIRS) offers the opportunity of a rapid measurement of forage dry matter concentration, allowing producers to make faster adjustments in real time. This study compared dry matter (DM) concentration predictions of three units of a portable near-infrared reflectance spectrometer (pNIRS) with conventional forced-air oven drying (48 h at 60 °C) using corn forage and silage samples. Moreover, a common on-farm method (Koster tester) was also compared. The reflectance curve used by pNIRS to predict DM was obtained by scanning WPCS samples and developed by SciO. A total of 113 whole-plant corn forage (WPCF) and 27 whole-plant corn silage (WPCS) samples from 66 corn hybrids were obtained from three separate experiments conducted between 2018 and 2019. These three experiments were completely independent of each other, with sample collections over different periods. In Experiment 1, all treatments were tested in WPCF, and the DM concentration of the forced-air oven differed from Koster testers (35.4 vs. 34.3% DM, on average, respectively) and all three pNIRS units (35.4 vs. 30.7% DM, on average, respectively), with no differences among pNIRS. All treatments were positively correlated with the forced-air oven treatment DM values. Experiment 2 evaluated the Koster tester and pNIRS in WPCF on farms, and the Koster tester differed from pNIRS (37.2 vs. 33.3% DM, on average, respectively) treatments. All pNIRS were positively correlated with Koster tester treatment. In Experiment 3, all treatments were tested in WPCS, and the DM concentration of the forced-air oven was greater than other treatments (35.3 vs. 32.8% DM, on average, respectively). Overall, Koster tester predictions for both Experiments 1 and 3 were better correlated with the forced-air oven than pNIRS. Additionally, pNIRS showed a lower mean bias, although low coefficients of determination and concordance correlation were observed in Experiment 3 compared to Experiments 1 and 2, which might be related to the prediction curve. Further calibrations of the predictive curve with forage samples would be needed to reasonably estimate the DM concentration of WPCF, whereas a greater number of samples could account for the variations in WPCS due to large heterogeneity in particle composition (e.g., leaves, stem, and kernel), size, and distribution. Full article