Search Results (7,146)

Durability deterioration and interlayer bonding failure of ultra-thin overlays remain critical challenges under coupled environmental and mechanical actions. Although environmental damage to asphalt mixtures has been widely investigated, the relationship between pore-structure evolution and interlayer fatigue deterioration in polymer-composite-modified ultra-thin overlays incorporating styrene–butadiene–styrene (SBS) and micro carbon fiber (MCF) remains insufficiently understood. This study therefore extends existing research by clarifying this relationship under freeze–thaw cycling and water immersion. Three-point bending and direct shear fatigue tests were conducted to evaluate bending and interlayer shear fatigue performance, respectively, while nanoindentation and X-ray computed tomography (CT) were used to characterize micromechanical properties and three-dimensional pore-structure evolution. The results showed that five freeze–thaw cycles reduced the bending fatigue life by 75.3% and the interlayer shear fatigue life by 49.6%, while six days of water immersion reduced the interlayer shear fatigue life by 55.1%. Freeze–thaw cycling promoted open-pore and pore-throat development and increased total porosity by 23.9%, contributing to aggregate displacement and redistribution of the internal skeleton. In contrast, immersion increased the proportion of small and closed pores, while isolated pores concentrated near the interlayer weakened interlayer shear resistance. Although immersion caused greater reductions in hardness and modulus, freeze–thaw-induced pore development was associated with greater deterioration in bending fatigue performance. Furthermore, an adaptive-network-based fuzzy inference system (ANFIS) was developed to predict pore tortuosity from equivalent diameter, shape factor, and porosity, with testing errors ranging from 0.102 to 0.129 for untreated, freeze–thaw, and immersed specimens. An exponential relationship was further identified between tortuosity and the pore comprehensive effect index (PCEI), providing a quantitative approach for characterizing pore connectivity and evaluating environmental deterioration in polymer-composite-modified asphalt concrete. Full article

The aim of this study is to investigate the mechanical performance of S-glass and E-glass fiber-reinforced epoxy composites manufactured using the hand-layup technique with epoxy resin (Lapox L-12) and hardener (K-6), cured for 24 h at room temperature. To investigate the effect of different configurations, six configurations were tested: pure S-glass/epoxy (Sc-E), pure E-glass/epoxy (Ec-E), and four combinations of S-glass/E-glass at different stacking sequences (1Hc-E, 2Hc-E, 3Hc-E, and 4Hc-E). All composites were fabricated with 60 wt% fiber and 40 wt% matrix. Mechanical characterization comprised tensile testing (crosshead speed 10 mm/min), three-point bending tests for flexural properties (5 mm/min), interlaminar shear strength (ILSS) testing (3 mm/min), and Shore D and Barcol hardness testing. The results showed that the ultimate tensile strength (188.42 MPa) and Young’s modulus (1.60 GPa) were highest for the Ec-E sample, while the peak load (8903.02 N) was highest for the Ec-E sample. For flexural properties, the 1Hc-E hybrid configuration (ss-ee-ss-ee) exhibited an excellent flexural strength of 416.60 MPa and a flexural modulus of 26.08 GPa, indicating a positive hybrid effect. The pure S-glass composites showed the best ILSS (16.52 MPa) and hardness properties. The study revealed that flexural properties can be optimized through strategic hybridization and that fiber stacking sequence has a significant effect on interlaminar properties. Full article

The beef industry is interested in quick, non-destructive methods to assess meat quality. This study evaluated the potential of laser-light backscattering imaging (LLBI) for assessing physicochemical properties and oxidative stress-related traits in Arouquesa beef, exploring its applicability as a non-invasive approach for detecting alterations potentially associated with pH. In 34 samples of Longissimus thoracis et lumborum (LTL) muscle from Arouquesa steers, the pH and oxidative stress biomarkers were quantified 24 h post-mortem, and backscatter images were obtained using green and red laser sources, with the areas corresponding to the core, inner ring, and outer ring of the diffusion patterns measured. After 7 days’ storage of the samples under vacuum at 4 °C, the measurements of oxidative stress biomarkers were repeated, and colour, water-holding capacity, sarcomere length (SL), and shear force (SF) were quantified. Significant correlations were found between LLBI parameters and pH 24 h post-mortem (pH_24h), colour coordinates, cooking losses (CL), drip losses (DL), and SF. Moreover, oxidative stress biomarkers also correlated with laser scattering parameters. Overall, LLBI demonstrated considerable potential as a rapid and non-invasive technique for assessing physicochemical quality attributes and oxidative stress-related traits in Arouquesa beef, supporting its application as an innovative tool for meat quality monitoring. Full article

The increasing generation of construction and demolition waste, along with the depletion of natural aggregates, has driven growing interest in recycled concrete aggregate (RCA) and reclaimed asphalt pavement (RAP) as sustainable alternatives in concrete production. However, a direct and systematic comparison between the two materials remains limited. This review addresses this gap by applying PRISMA guidelines to analyze 82 peer-reviewed studies published between 2010 and 2026. Both materials are evaluated across three key domains: physical properties, mechanical performance, and microstructural characteristics. The findings indicate that RCA can reduce compressive strength by up to 26%, mainly due to the presence of porous adhered mortar and a complex interfacial transition zone (ITZ). In contrast, RAP weakens bonding with cement paste because of its hydrophobic bituminous coating, leading to adhesive failure at the mortar asphalt interface. Despite these limitations, RCA and RAP exhibit distinct behaviors in terms of shear capacity, ductility, energy absorption, and durability. Enhancement techniques such as surface treatment, carbonation, supplementary cementitious materials, and fiber reinforcement show potential in improving performance. Additionally, life cycle and economic analyses reveal that RAP can reduce total costs and carbon emissions when efficiently processed. This study provides a unified comparative framework to support sustainable material selection and design optimization. Full article

Existing studies on selective pepper harvesting commonly use the pedicel as the picking target. However, for Hang pepper, dense branches and leaves cause severe fruit stem occlusion, resulting in a low harvesting success rate. To address this limitation, an end-effector that uses the fruit body as the picking target was designed in this study. Physical property tests of Hang pepper were first conducted. In radial compression tests, a post-release deformation of less than 5% was used as the criterion for low-damage clamping. The maximum allowable clamping force was determined to be 3.5 N, under which the maximum fruit compression ratio was 10%. The maximum cutting force required to shear the pedicel was 15.03 N. Based on these results, a harvesting strategy consisting of fruit clamping, fruit pull-down, and pedicel cutting was proposed. A five-bar linkage was adopted as the main mechanism of the end-effector, and its kinematic and mechanical models were established. Taking the minimum driving torque as the optimization objective, a genetic algorithm was used to optimize the linkage dimensions. The optimized driving torque was 0.801 N m, and a calculation method relating the target fruit diameter to the servo rotation angle was established. Harvesting experiments under prescribed target diameters showed a harvesting success rate of 95%, and the single-fruit harvesting time was 5.1 s, demonstrating the excellent harvesting capability of the proposed end-effector. Full article

In this work, a formaldehyde-free bio-based wood adhesive was successfully fabricated using epoxidized soybean oil (ESO) cross-linked with maleic anhydride (MA) and carboxylated lignin sulfonate (CLS). The effect of CLS substitution dosage on the bonding performance was systematically investigated. The results indicated that the dry shear strength and wet shear strength of the adhesive exhibited a typical non-monotonic variation with increasing CLS content, reaching the maximum values of 1.79 MPa and 1.38 MPa, respectively, at a CLS substitution ratio of 40 mol% relative to MA. These mechanical properties fully meet and exceed the requirements of the Chinese national standard for wood adhesives. Orthogonal experiments were further conducted to optimize the hot-pressing process parameters and the optimal conditions were determined as follows: hot-pressing temperature of 130 °C, pressing time of 10 min, glue spread of 280 g/m², and pre-mixing time of 70 min. FTIR, DSC, and TGA characterizations confirmed the complete curing reaction of the adhesive system. The introduced CLS served as both a reactive curing agent and an efficient catalytic component, which effectively reduced the curing temperature, while the incorporation of MA significantly improved the thermal stability of the cured adhesive. This study provides a feasible strategy for the preparation of high-performance, low-cost, and environmentally friendly bio-based wood adhesives. Full article

To overcome the limitations of conventional biopolymer films and reduce reliance on petroleum-based plastics, a nacre-inspired film was developed via 3D printing. During printing process, shear-induced alignment of mica flakes was achieved within a sodium alginate/xanthan gum matrix. Additionally, zinc oxide nanoparticles (ZnO NPs) were incorporated to achieve a synergistic reinforcement effect. Structural analysis revealed that the mica flakes within the film exhibited an oriented distribution, with ZnO NPs uniformly embedded in the interlayer voids, and hydrogen bonding assisted in forming a dense network of the components. Performance testing showed that the tensile strength rose from 13.8 MPa to 62.9 MPa. Improvements in water resistance and thermal stability were also observed. Furthermore, the material exhibited outstanding comprehensive protective properties, including a low water vapor permeability value of 7.587 × 10⁻¹¹ g·m/m²·Pa·s, an ultraviolet blocking rate of 99.37% at a wavelength of 280 nm, and the ability to completely inhibit target bacterial strains, while also possessing good biodegradability and recyclability. Shelf-life tests indicated that the film fabricated in this work could notably prolong the shelf life of strawberries. Biocompatibility test results indicated that the film was safe and non-toxic, and showed no significant cytotoxicity. Full article

Zirconia orthodontic brackets exhibit favorable mechanical and esthetic properties; however, their chemically inert surfaces can limit adhesion to resin cements. This study evaluated the effect of multi-gas atmospheric plasma irradiation on the shear bond strength (SBS) of zirconia brackets. Zirconia brackets were treated with nitrogen (N₂), argon (Ar), or air plasma for 3 and 10 s and compared with untreated controls and conventional alumina-sandblasted specimens. Surface wettability was assessed by contact angle measurements, and surface chemical changes were analyzed using Fourier transform infrared (FT-IR) spectroscopy. After 10 s of plasma treatment, the water-contact angle decreased from 64.3° ± 8.4° in the untreated group to 17.9° ± 6.4°, 18.8° ± 2.7°, and 16.8° ± 5.3° with Ar, N₂, and air, respectively. For SBS testing, zirconia brackets were bonded to bovine enamel, stored in distilled water at 37 °C for 24 h, and subsequently tested (n = 12–15 per group). The mean SBS was 20.99 ± 2.87 MPa for the untreated group, 25.50 ± 2.40 MPa for the sandblasted group, and 23.63 ± 3.33, 23.99 ± 3.26, and 23.98 ± 3.58 MPa after 10-s Ar, N₂, and air plasma treatment, respectively. FT-IR revealed no new absorption peaks. Within the limitations of this study, multi-gas atmospheric plasma treatment markedly reduced the apparent water-contact angle measured on flat zirconia specimens, whereas its effect on SBS relative to the untreated group was not statistically significant. Full article

Functionally graded (FG) beams have been used more and more in highly designed structures under dynamic loading due to their graded mechanical properties and excellent performance. Their transient response on complex elastic foundations is, however, not easily predicted due to the material heterogeneity, shear deformation, rotary inertia, and coupled effect of the foundation parameters. The purpose of this study is thus to propose an accurate and efficient computational model for the dynamic analysis of FG Timoshenko beams supported by biparametric Vlasov foundations under harmonic excitation. The formulation takes into account the space-varying material properties, Timoshenko shear deformation, rotary inertia, and coupled Winkler–shear interaction of the Vlasov foundation. The governing equations are numerically solved in space with the high-order spectral element method (SEM) and in time with the Hilber–Hughes–Taylor (HHT) scheme. The resulting framework is used to study the transient displacement and vibration response with respect to the excitation frequency, material gradation index, and stiffness and damping properties of the foundation. The numerical results prove that the results converge quickly in space and time and also indicate that the dynamic response is significantly affected by the interaction between the gradation of material and the parameters of the foundation. The displacement amplitude, resonance behavior, and vibration characteristics are significantly altered by any variations in the gradation index and foundation characteristics. The results obtained with the proposed formulation are in good agreement with those available from the benchmark solutions, thus validating the correctness and reliability of the formulation. The SEM–HHT methodology offers a reliable, precise, and low-computational-cost solution for transient analysis of FG Timoshenko beams on biparametric Vlasov foundations under harmonic excitation. The proposed framework offers a powerful predictive tool for vibration analysis, response control, and design of advanced FG beam systems that can be applied in aerospace, marine, smart infrastructure, and other high-performance engineering structures. Full article

A carbide-slag-activated slag-fly ash geopolymer (CSF) and waste gold tailings sand were used to co-stabilize mucky soil, aiming to promote the valorization of multiple industrial solid wastes and provide a low-carbon treatment approach for mucky soil in river and lake regions. Unconfined compression, direct shear, water stability, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), and heavy metal leaching tests were conducted to investigate the effects of CSF and gold tailings sand contents on the mechanical properties, water stability, microstructure, and environmental safety of the stabilized soil. The results showed that the unconfined compressive strength (UCS) and shear strength increased with increasing CSF content, whereas the strength gain became marginal when the CSF content exceeded 15%. With the CSF content fixed at 15%, both the strength and water stability initially increased and then decreased as the gold tailings sand content increased. The CSF15-G30 specimen exhibited favorable overall performance, with 7 d and 28 d UCS values of 0.65 and 1.53 MPa, respectively, representing increases of 25.0% and 12.5% relative to CSF15. Its cohesion and internal friction angle reached 88.21 kPa and 47.13°, corresponding to increases of 44.5% and 8.1%, respectively. The water stability coefficients at 7 d and 28 d were 76.9% and 87.6%, respectively. SEM-EDS observations indicated that the cementitious products generated by CSF, together with the filling and skeletal effects of gold tailings sand, enhanced interparticle bonding and matrix densification. Although the concentrations of leached heavy metals increased with increasing gold tailings sand content, all measured values remained below the relevant leaching-toxicity limits. These results demonstrate that an appropriate amount of gold tailings sand can effectively improve the mechanical properties and water stability of CSF-stabilized mucky soil while maintaining satisfactory environmental compatibility. Full article

Underground coal mining can induce deformation and failure of overlying strata and ground surface, which seriously endangers the safety of human life and property. During mining, the immediate roof rock successively experiences initial caving (fixed support on four sides) and periodic caving (fixed support on three sides and free on one side). Different boundary conditions alter the unloading and deformation processes such as cracking and fracturing of immediate roof rock, thereby affecting its subsequent mechanical behavior of compaction and deformation, and resulting in differences in the movement law of overlying strata. In this paper, the numerical simulation method is adopted to investigate the variation laws of unloading and fracturing characteristics of immediate roof rock under initial caving and periodic caving with thickness-width ratio (t/w), length-width ratio (l/w), unloading stress (σ_u) and specimen strength (σ_c), and the corresponding action mechanism is revealed. The fractal evolution law of fractured immediate roof rock obtained from this study can quantitatively evaluate the compaction characteristics of caved rock, provide refined parameter support for surface subsidence prediction and possess guiding significance for stope surrounding rock control engineering. The results show that the fragments formed after the failure of immediate roof rock are mainly block-strip shaped under both first caving and periodic caving conditions. With the increase in the thickness-width ratio, the flexural rigidity of immediate roof rock increases and crack propagation is restrained, so that the particle-size–mass fractal dimension of fragments increases first and then decreases for the two caving modes. The increase in length-width ratio weakens the propagation of secondary fractures and raises the particle size of fragments, while the overall variation in particle-size–mass fractal dimension is small under the two working conditions. As the unloading stress continuously rises, the coupled tension-shear effect inside the rock gradually intensifies, and the failure mode changes from tension-shear failure to global shear failure. Accordingly, both the particle-size–mass fractal dimension and fractal dimension of crack distribution increase first and then decrease under first caving and periodic caving conditions. The increase in the strength of immediate roof rock raises the energy consumption during rock failure, and large-size fragments are more likely to be generated, which reduces the particle-size–mass fractal dimension and increases the particle size of fragments under both caving modes. Meanwhile, internal micro-fractures continuously initiate and propagate with the growth of rock strength. For specimens with relatively high strength, crack propagation is inhibited and the development of secondary fractures is weakened, leading to an evolution trend that the fractal dimension of crack distribution increases first and then decreases. Under identical parameter conditions, the particle-size distribution and crack complexity for first caving are mainly affected by geometric parameters; the particle size of fragments is primarily controlled by specimen strength; and the unloading stress threshold governs the transition of failure mode. For periodic caving, the crack-initiation location is first determined by asymmetric boundary constraints. The thickness-width ratio dominates the particle-size distribution of fragments, and unloading stress as well as specimen strength further regulate the complexity of cracks. Full article

The development of sustainable, nutrient-dense food systems requires a comprehensive understanding of how microalgae influence the mechanical properties of starch hydrogels. While certain microalgae are common food additives, a critical research gap remains regarding their effect on the rheological behavior and structural integrity of potato starch gels specifically. This study addressed this gap by evaluating the mechanical, microstructural and optical impacts of Arthrospira platensis (commonly known as Spirulina) and Chlorella vulgaris at 0.5%, 1% and 2% (w/w). Utilizing steady-shear flow tests, colorimetry, NIR spectroscopy and microscopy, we characterized changes in steady rheological parameters, color, chemical changes and microstructure of fortified hydrogels. Results indicated that filamentous Arthrospira platensis reinforces the matrix, significantly increasing yield stress from 10.2 Pa in the control to 32.4 Pa at 2% inclusion. In contrast, spherical Chlorella vulgaris appears to act as a structural filler, reducing yield stress to 4.8 Pa at 2%. Microscopy confirmed these morphological influences, showing Arthrospira platensis filaments entangling granules while Chlorella cells integrated into inter-granular spaces. Colorimetry revealed significant darkening (L* decreased from 31.59 to 18.54 at 2% Spirulina addition) and significant greening (p < 0.05). NIR spectroscopy demonstrated potential physical interactions via vibrational markers at 5172 cm⁻¹ and 5646 cm⁻¹, indicating water matrix redistribution within the system. This research demonstrates how incorporating Spirulina and Chlorella vulgaris provides a viable approach for modifying the physical properties of starch-based matrices. The findings indicate that Spirulina enhances flow resistance and structural stability under steady shear, whereas Chlorella vulgaris reduces flow barriers, thereby increasing the spreadability of these composite food systems. Full article

A simply supported rectangular isotropic ferromagnetic plate with magnetocaloric properties subjected to convective heating on its upper surface is considered. The governing equations comprise a system of two-dimensional transient equations for the thickness-averaged temperature characteristics of the plate and the two-dimensional bending equations for isotropic plates expressed in terms of generalized displacements within the framework of first-order shear deformation theory. Closed-form solutions to the governing equations are obtained by expanding all thermal and mechanical field quantities in double Fourier sine series satisfying the prescribed boundary conditions, combined with the Laplace transform in time applied to the thermal quantities. A comparative numerical analysis is carried out for the magnetocaloric ferromagnetic plate and a carbon steel plate under ambient temperature rising at a finite rate to a prescribed value. The dependences of all quantities under investigation on the ambient temperature rise rate, time, convective heat transfer coefficient, thermal conductivity of the ferromagnetic material, and geometric parameters of the plate are analyzed and presented graphically. The results obtained provide a quantitative basis for assessing the thermoelastic state and for optimizing the geometry and operating conditions of active magnetic regenerator plate stacks with a view to enhancing their structural reliability. Full article

Extrusion-based bioprinting imposes stringent mechanical constraints on bioink formulations, yet the rheological parameters governing cell survival during the printing process are rarely reported in a standardized way, limiting cross-study comparison. In this work, we systematically characterized the viscoelastic properties of alginate/methylcellulose bioinks incorporating strontium-enriched hydroxyapatite (Sr-OHAp) particles and Poloxamer 188, and assessed their effect on PANC-1 cell viability in bioprinted constructs. The power law consistency index K and pseudoplasticity index n were used as quantitative descriptors of bioink behavior. Addition of Poloxamer 188 reduced K by 52.1% in particle-free inks and by 64.6% in particle-containing inks, while n remained largely unchanged (≤2% variation), indicating that particles selectively modulate consistency without compromising shear-thinning behavior. On day 1, bioprinted constructs showed lower cell viability than cell-seeded scaffolds (53.9–58.9% vs. 96.7%); however, constructs containing Sr-OHAp (B3) displayed progressive recovery, reaching 84.0% viability by day 7, compared to 72.9% for particle-free bioinks (B1). These results demonstrate that Sr-OHAp particles act as rheological sensitizers that reduce extrusion-induced shear stress while simultaneously promoting long-term cell recovery, likely through their bioactive surface chemistry. We propose that systematic reporting of K and n indices should become standard practice in bioprinting studies to enable rational bioink design and consistent knowledge accumulation across the field. Full article

Viscous fingering is a canonical nonlinear interfacial instability that arises when a less viscous fluid displaces a more viscous one under an adverse viscosity contrast. Despite extensive investigations into the effects of fluid properties, operating conditions, and rheology, systems involving a shear-thickening displaced phase remain largely unexplored. Here, three-dimensional numerical simulations of immiscible air–fluid displacement in a Hele–Shaw cell are performed to elucidate how interfacial tension, air-inlet velocity, and gap-depth gradient regulate instability evolution. Increasing interfacial tension strengthens the Laplace-pressure barrier, suppresses shear-induced necking and pinch-off, and preserves finger topology; however, it intensifies flow diversion and delays the advancement of the central finger. Increasing the inlet velocity markedly amplifies the local interfacial shear rate and triggers pronounced shear thickening. The resulting viscous-resistance barrier redistributes momentum toward paths of least hydraulic resistance, directly promoting tip splitting and severe topological breakup. Even a small gap-depth gradient reorganizes the local hydraulic resistance and pressure field. Positive and negative gradients induce resistance-reduction and throttling effects, respectively, generating pronounced pressure shielding that governs asymmetric momentum transfer and preferential flow-path selection. These findings identify the capillary, rheological, and geometric mechanisms controlling viscous fingering during the air-driven displacement of shear-thickening fluids. Because such instabilities compromise the integrity of geological-fracture seals and the operating efficiency of semi-solid flow batteries, this study provides a mechanistic basis for stabilizing immiscible displacement and optimizing industrial fluid-transport systems. Full article