Search Results (9,098)

In this work, we present a theoretical study of InPO₄ under pressure. Total-energy calculations based on density functional theory were performed to explore the crystal structure of InPO₄ in light of the recent X-ray diffraction characterization of this compound under pressure. A phase coexistence was observed above 10 GPa, involving the ambient-pressure CrVO₄-type structure and the high-pressure scheelite and zircon phases. Therefore, the previously performed analysis of InPO₄ behavior under pressure is extended by simulating X-ray spectra and interplanar distances for the three polymorphs. In addition, the elastic behavior of the three phases is analyzed to assess the elastic stability of InPO₄ under pressure and to compute the mechanical properties and elastic anisotropy. Our findings significantly extend previous experimental results on the compressibility of InPO₄, which were limited to the ambient-pressure phase. Moreover, our results unambiguously reveal a marked difference in the elastic properties of the scheelite and zircon phases under pressure, showing that the zircon phase is elastically unstable at high pressures. This suggests that the reported coexistence of phases may result from kinetic barriers or from non-hydrostatic conditions within the diamond anvil cell caused by the pressure-transmitting medium. Full article

In this study, the influence of thermal loading in a supersonic flight environment on the mechanical stiffness of elastic structures and the corresponding aeroelastic stability limits is investigated analytically. Recognizing that elevated temperatures inherently alter constituent elastic properties, a temperature-dependent continuous elasticity framework is incorporated directly into the governing differential operators of the structural domain. The macro-mechanical behavior of representative panel- and wing-type elements is modeled utilizing the Euler–Bernoulli beam formulation, while high-speed supersonic aerodynamic effects are represented through linearized first-order piston theory. The continuous spatial displacement fields are discretized by means of a modal expansion, and the coupled aeroelastic system is subsequently transformed into a finite set of dynamic state-space equations using the Ritz–Galerkin truncation method. The numerical and analytical outputs demonstrate that aerothermal softening not only induces continuous erosion in the material stiffness but also directly modulates the aeroelastic pole trajectories, thereby prematurely contracting the safe supersonic flight envelope. The primary novelty of the proposed framework lies in the derivation of explicit analytical expressions that directly map temperature-dependent stiffness variations onto supersonic aeroelastic instability boundaries. Because this approach is formulated in a generalized analytical form, it can be applied across diverse material systems, geometric profiles, and thermal conditions with reduced computational overhead compared to full fluid–structure interaction solvers, thereby providing a theoretical basis for preliminary stability assessment of supersonic aerospace configurations operating under high-temperature conditions. Full article

In this work, a non-standardized hypereutectic aluminum–silicon alloy AlSi21Cu5MgCr intended for the automotive industry is presented. The modification of the alloy is performed with the conventional modifier phosphorus in an amount of 0.04 wt%. The applied metallurgical treatment is the basis for the obtained modified structure. It has been established that after conducting the T6 heat treatment, the free silicon crystals are reduced to 26.9 µm, and the eutectic silicon crystals are spherical in shape and have dimensions not exceeding 8 µm. The macrohardness of the studied alloy is 168.5HV_10/10, a value significantly higher than that required for this type of alloy, which is in the range of 95 ÷ 137 HV (90 ÷ 130 HB). The microhardness of the α-phase in the composition of the eutectic is 154 µHV_50/10, which indicates that after quenching a saturated solid solution was fixed, and during the artificial aging process secondary strengthening phases were formed and separated. A CrAlN hard coating was deposited on the alloy surface. The mechanical properties of the coating were characterized by a hardness of 14 GPa, whereas the AlSi21Cu5MgCr substrate had a hardness of 2 GPa. The results showed considerable improvement of the hardness of the new alloy and well-tuned elastic–plastic properties. The obtained adhesive properties are compatible with this class of materials. The composition of the CrAlN hard coating is homogeneously distributed on the alloy surface and the morphology is improved. The investigations showed that CrAlN hard coatings could successfully be applied for the modification of the surface of AlSIMgCu alloys. Full article

The application of continuous carbon fiber (CCF) can reinforce the mechanical properties of 3D-printed parts, but the effect of reinforcement layer distribution on composite performance remains unclear. This study investigates the effect of concentrated and separated distributions of CCF layers with different numbers of reinforcement layers. Tensile and flexural tests are conducted in accordance with ASTM D5083 and ASTM D790, respectively. Under the conditions of a solid-filled matrix (Onyx) and 0° CCF deposition, both concentrated and separated CCF layers improve several mechanical properties. Compared with pure Onyx, one-layer CCF increases the tensile modulus by about six times and more than doubles the tensile strength. Increasing the CCF volume leads to further increases in these properties. With concentrated three-layer CCF, the tensile modulus and tensile strength reach 7.153 ± 0.090 GPa and 109.045 ± 5.124 MPa, respectively. For flexural properties, separated two- and three-layer CCFs significantly improve the tangent modulus of elasticity from 0.467 ± 0.106 GPa for pure Onyx to 2.246 ± 0.333 GPa and 3.394 ± 0.081 GPa, respectively. This study also compares the tensile and flexural strength-to-weight ratio of all specimen groups and analyzes the failure mechanisms based on macroscopic fracture appearance. The results can provide guidance for selecting appropriate CCF layer distribution strategies to reinforce composites in different applications. Full article

In this paper, we investigate the existence and positivity of solutions for a class of twelfth-order nonlinear boundary value problems that naturally arise in the mathematical modeling of elastic and micro-mechanical systems. The considered model incorporates higher-order derivatives to account for nonlocal and gradient effects that commonly appear in the analysis of micro- and nano-scale elastic structures. By employing the Leray–Schauder nonlinear alternative and fixed point theorems, we establish sufficient conditions for the existence of at least one positive solution. The analysis relies on the explicit construction and properties of the associated Green’s function, which plays a fundamental role in deriving upper and lower bounds for the nonlinear term. The obtained results extend and generalize earlier works on sixth, eighth and tenth-order problems to the twelfth-order case. Finally, numerical examples are presented to illustrate the applicability and accuracy of the theoretical findings. The results provide a rigorous analytical foundation for the study of high-order elastic models and micro-scale structural stability. Full article

In lignite open-pit mines, the blasting mining method and large-scale mechanical shovelling processes induce substantial cyclic disturbances in coal seams at the terminal slope during lignite extraction, significantly increasing the risk of slope destabilisation and damage. Consequently, uniaxial cyclic loading and unloading experiments were conducted to evaluate the mechanical properties and energy evolution of lignite. Acoustic emission (AE) characteristics and macroscopic crack evolution of lignite under cyclic loading and unloading conditions were analysed using AE counts and b-values. The energy evolution of lignite was further examined to elucidate the mechanisms of crack propagation and instability failure. The results indicate that initial damage exists within the lignite, and cyclic loading weakens its mechanical properties. Specifically, the irrecoverable damage resulting from the continuous development of internal cracks leads to the continuous deterioration of the mechanical properties of lignite. During the process of damage accumulation, the energy evolution characteristics of the lignite shift from being dominated by plastic energy dissipation to being dominated by elastic energy storage, which triggers higher energy dissipation and release at the cumulative damage stage. Furthermore, as the stress level increases, the cracks in the lignite transition from tensile–shear composite cracks to predominantly tensile cracks. These findings provide critical insights into the mechanisms of instability and failure in open-pit slopes subjected to cyclic loading and unloading, contributing to the advancement of slope stability management in lignite mining operations. Full article

Background: N-Acetylneuraminic acid (Neu5Ac), the predominant form of sialic acid, exhibits potent antioxidant, anti-inflammatory, and anti-glycation properties in preclinical studies, suggesting potential dermatological benefits. However, robust clinical evidence supporting the efficacy of oral Neu5Ac supplementation on human skin conditions remains lacking. Methods: A randomized, double-blind, placebo-controlled trial was conducted with 55 Chinese women (40–65 years) who received 120 mg/day Neu5Ac (n = 27) or a matching placebo (n = 28) for 84 days. Skin pigmentation, hydration, biomechanical properties, and dermis echogenicity were evaluated at baseline, D28, D56, and D84 using standardized clinical and instrumental assessments. Results: Both clinical (Pantone color card) and instrumental (photographic) assessments showed that oral Neu5Ac supplementation significantly improved skin lightness on both pigmentary spots and surrounding normal skin compared with placebo at day 84. In addition, stratum corneum hydration and skin biologic extensibility were significantly increased in the Neu5Ac group. Dermal echogenicity showed numerical improvement but did not reach statistical significance. Self-assessment indicated that 100% of the Neu5Ac participants reported improvements in skin whiteness, radiance, elasticity, firmness, and hydration, with mean satisfaction scores of 9.1/10 versus 7.9/10 for placebo. Conclusions: Daily oral supplementation with 120 mg Neu5Ac for 84 days significantly promoted localized spot brightening, enhanced skin hydration, and improved skin elasticity, providing the first clinical evidence supporting Neu5Ac as a safe and effective oral cosmetic ingredient for skin anti-aging. Full article

Astragalus membranaceus, a medicinal plant used in traditional Chinese medicine for centuries, has attracted growing scientific attention for its potential anti-aging and anticancer properties, particularly for skin and bone health. Its key bioactive compounds like astragalosides, cycloastragenol, and its commercial derivative TA-65, have been associated with telomerase activation and telomere maintenance, suggesting a possible role in modulating cellular senescence and tissue repair processes. In addition to the claimed telomere maintenance, A. membranaceus exhibits antioxidant, anti-inflammatory, and DNA-protective activities, properties that contribute to its anti-aging effects. Emerging evidence also suggests that telomerase modulation by A. membranaceus influences cancer cell dynamics, either suppressing tumor progression through immune regulation and apoptosis induction or, in some contexts, potentially promoting tumor growth. This duality highlights the importance of dose, formulation, and targeted application. Clinically, TA-65 has been reported to improve vascular health, bone mineral density, and skin elasticity in aging individuals. Preclinical studies further support its protective effects against osteoporotic bone loss and photoaging-induced dermal degeneration. This review summarizes the phytochemical composition of A. membranaceus and critically evaluates the mechanistic and therapeutic evidence underlying its anti-aging and anticancer actions on skin and bone tissues. It also discusses the pharmacokinetic properties of A. membranaceus, including its absorption, bioavailability, and safety profile. The integration of A. membranaceus into evidence-based senile therapeutic strategies holds promise, but further mechanistic and clinical studies are required to optimize its safety and efficacy. Full article

To clarify the influence of α (rock–coal height ratio) and λ (rock–coal strength ratio) on the mechanical properties and failure characteristics of coal–rock composite specimens, where the weaker component varies with rock properties, four sets of coal–rock composite specimens with λ values of 0.26, 0.35, 0.59, and 3.81 were subjected to uniaxial compression tests under conditions of α = 1:3, 1:1, and 3:1. The results show that: There are significant differences in the mechanical properties of coal–rock composite specimens compared to individual coal and rock specimens. Both α and λ have significant effects on the mechanical properties and failure modes of coal–rock composite specimens. The variation in uniaxial compressive strength, elastic modulus, and peak strain in coal–rock composite specimens with respect to α is significantly influenced by rock properties. These variation patterns are not entirely identical for different rock properties. For coal–rock composite specimens at different α values, the trends in uniaxial compressive strength, elastic modulus, and peak strain as a function of λ are identical. Both uniaxial compressive strength and elastic modulus exhibit a pattern of increasing rapidly at first and then more slowly with increasing λ, and both can be quantitatively described by exponential functions. Peak strain follows a pattern of rapid decrease, rapid increase, and gradual increase with increasing λ. However, for any given change in λ, the magnitude of the changes in uniaxial compressive strength, elastic modulus, and peak strain is significantly influenced by α. When λ is small or large, the weaker component in the coal–rock composite specimen is the primary source of failure. When λ falls within a certain range, both the strong and weak components undergo relatively complete failure. When λ increases beyond a critical value, only the weaker component fails, while the stronger component remains intact and does not fail. As α increases, the degree of failure in the coal–rock composite specimen gradually decreases. Full article

To address the environmental issues arising from the large-scale stockpiling of steel slag and to explore its efficient utilisation in road sub-bases, this study investigated the effects of cement dosage and steel slag content on the mechanical properties of cement-stabilised steel slag mixtures. Through unconfined compressive strength tests, compressive modulus of elasticity tests and splitting tensile strength tests, the study revealed the mechanisms by which cement dosage and steel slag content influence microstructure. The results indicate that as the cement content increases, the unconfined compressive strength, compressive modulus of elasticity and splitting tensile strength all show an upward trend, although the rate of increase gradually decreases. With increasing steel slag content, the unconfined compressive strength and splitting tensile strength first increase and then decrease slightly, whilst the compressive modulus of elasticity continues to rise. When 60% steel slag was incorporated, the 28-day unconfined compressive strength and splitting tensile strength reached their peak values, representing increases of 22.17% and 72.7% respectively compared to the control group. Further examination of the microstructure revealed that increasing the cement content and steel slag content enhances structural density and reduces surface porosity; however, excessive cement content and steel slag content have an adverse effect on mechanical properties. Consequently, the synergistic effect of an appropriate amount of steel slag and cement can significantly improve the mechanical properties and microstructure of the mixture. These findings are of great significance in promoting the green utilisation of solid waste materials, such as steel slag, in road engineering. Full article

In this work, we develop machine-learned moment tensor potentials (MTPs) to simulate the static and dynamic structural properties in Al_xGa_1−xN and related materials. The potentials are trained on DFT-calculated data for forces, stresses, and energies obtained from random atomic displacements and cell deformations. MTP-calculated physical properties, including lattice parameters and elastic constants, thermal expansion, harmonic and anharmonic vibrational properties, and the thermal conductivity, are benchmarked against first-principles results and experimental data. The comparisons testify to the very high accuracy achieved by the machine-learned potentials despite the massively reduced computational effort. Additionally, the impact of various aspects of the MTP training procedure is examined. Full article

This study evaluated the effectiveness of maleic anhydride polypropylene (MAPP) in improving the mechanical performance and interfacial adhesion of lignocellulosic fiber-reinforced polypropylene (PP) composites. Based on Scanning Electron Microscopy (SEM) investigations, the relationship between fiber fraction, MAPP content, mechanical characteristics, and fracture morphology was the main focus. The test results showed that the stiffness and tensile strength of the composites increased with the addition of MAPP. The esterification reaction between the anhydride groups of MAPP and the hydroxyl groups of the fibers strengthened the interphase covalent bond, with the 46:50:4 composition producing the highest elastic modulus of 79.67 MPa and maximum tensile stress of 11.01 MPa. The dense interphase zone, few gaps, and no dominant fiber tension were all confirmed by SEM morphology, and also indicated effective stress transfer from the PP matrix to the fibers. However, the toughness of the material decreased significantly with increasing stiffness. Due to strong plastic deformation in the PP matrix that is not tightly attached to the fibers, the composition without MAPP (30:70:0) shows high impact energy and breaking strain, reaching 25.39 kJ/m² and 121.26%, respectively. The increase in chemical bonding at 4% MAPP content limits the mobility of the polymer chains, making it more brittle. In addition, even though MAPP is still present in the system, increasing the fiber fraction above 60% causes agglomeration, decreased homogeneity, and increased voids due to limited matrix wetting, ultimately deteriorating the mechanical properties. Tensile stress and elastic modulus have a very strong positive correlation (R² = 0.93), while impact energy and strain have a good correlation (R² = 0.89). The results overall showed that the ideal MAPP dosage is in the range of 4% before interface saturation occurs and confirmed that MAPP efficiency is determined by the balance between fiber composition, MAPP quantity, and dispersion homogeneity. Full article

Allergic asthma is among the type 2-driven chronic inflammatory allergic diseases. Osteoimmunological findings indicate that shared systemic immune mediators and persistent inflammation can disrupt skeletal homeostasis and promote bone fragility. Treatment commonly includes inhaled corticosteroids like fluticasone propionate (FP) to suppress inflammation, with anti-immunoglobulin E (anti-IgE) biologics added to interrupt the IgE-mediated allergic cascade. TNF-α inhibitors (anti-TNF) are also being studied for their impact on inflammatory pathways. However, their capacity to preserve bone mechanical/mineral integrity in allergic airway inflammation (AAI) remains unclear. This study compared the efficacy of anti-TNF, FP, and anti-IgE monotherapies and an FP/anti-IgE combination in mitigating AAI-induced deficits in bone mechanical/mineral integrity in an ovalbumin (OVA)-induced chronic murine AAI model. Fifty-six male BALB/c mice (8–10 weeks old; 22–24 g) were randomly assigned to control, AAI (OVA-sensitized/challenged), and five treatment cohorts: FP (2000 μg), low-/high-dose anti-IgE (aIgE-L/aIgE-H; 100/200 μg), anti-TNF (aTNF; 6.25 mg/kg-bw), and FP/aIgE-H combination. Following an 8-week protocol, three-point bending and inductively coupled plasma-mass spectrometry (ICP-MS) were used to assess bone mechanical properties and physicochemical characteristics of the mineral phase (calcium (Ca) and phosphorus (P) levels; stoichiometric Ca/P ratio), respectively. Analyses showed that aIgE-L and FP monotherapies failed to mitigate AAI-induced bone changes. aTNF and aIgE-H monotherapies provided comparable protection of cross-sectional properties, rigidity, energy-to-fracture, elastic modulus, and yield/ultimate moments; however, aIgE-H was more efficacious in preserving Ca and P levels and the stoichiometric Ca/P ratio. The FP/aIgE-H combination demonstrated the greatest efficacy in preventing mechanical deterioration and preserving mineral integrity, suggesting it as the optimal strategy for maintaining skeletal health in the management of type 2-driven AAI. Full article

To address the lack of systematic quantitative studies on waterborne epoxy resin (WER)-modified emulsified asphalt regarding its rheological optimization and engineering applicability, this study fills the gap by preparing WER-modified emulsified asphalt via a two-step process. New findings reveal that 20% WER content significantly enhances elastic components, creep–recovery, fatigue life, and fracture energy. The main objective is to establish a theoretical basis for high-performance pavement materials. Modified emulsified asphalt specimens with different waterborne epoxy resin contents were prepared using a two-step method of “emulsification followed by compounding”. The stability of the emulsions was quantitatively evaluated by zeta potential, storage stability, particle size distribution, and demulsification time. Their rheological parameters, multi-stress creep–recovery characteristics, fatigue life, and low-temperature crack resistance were systematically tested across the full temperature range using a dynamic shear rheometer and a bending beam rheometer. In addition, the bonding performance, strength development behavior, and water resistance durability were comprehensively assessed through pull-out tests, Marshall stability and splitting strength tests, as well as freeze–thaw cycle tests. These properties were compared with those of unmodified emulsified asphalt (UEA-0) and SBR-modified emulsified asphalt (SBR-EA). With an increase in waterborne epoxy resin content, the elastic component of the modified asphalt improved significantly, and the phase angle continuously decreased. The specimen with 20% waterborne epoxy resin content (WER-EA-20) exhibited the best performance: its phase angle was lower than those of the other groups under high-, medium-, and low-temperature conditions. After seven creep–recovery cycles, its creep–recovery rate remained at 33%, substantially higher than the 8% observed for the unmodified specimen. The fatigue life reached 15,000 cycles under a shear stress of 2.1 MPa. At −10 °C, the fracture strength was 0.92 MPa, and the fracture energy reached 21.4 J. Furthermore, the pull-out strength of WER-EA-20 was 0.86 MPa, with the failure mode identified as asphalt cohesive failure. After 37 days of curing, the Marshall stability reached 22.5 kN, and the splitting strength was 1.36 MPa. After 40 freeze–thaw cycles, the freeze–thaw splitting strength ratio (TSR) of WER-EA-20 remained above 75%, representing an improvement of more than 110% compared to the unmodified UEA-0 (TSR ≈ 35.5%), which highlights the significant enhancement in water resistance imparted by the waterborne epoxy resin. Compared to SBR-EA, WER-EA-20 has a higher softening point, a lower suitable mixing temperature, and better anti-aging properties. Waterborne epoxy resin can effectively improve the viscoelastic properties and overall road performance of emulsified asphalt, and the modification effect increases with increasing dosage. Full article

Multi-field coupled numerical analysis and strain monitoring experiments were conducted for the curing process of a ring-shaped CFRP component. The curing kinetics and mechanical properties of LD-2184 epoxy resin were characterized using non-isothermal DSC, tensile testing, and CTE measurements. The curing reaction follows a single-stage autocatalytic mechanism with an activation energy of 54.73 kJ·mol⁻¹. A piecewise curing kinetics equation was established. The elastic modulus of the fully cured resin is 2.810 GPa, and the coefficient of thermal expansion is 6.060 × 10⁻⁵ K⁻¹. Composite ring specimens were fabricated using a wet winding process. FBG sensors were embedded to monitor axial strain during curing. A coupled numerical model was developed that includes heat conduction, curing kinetics, and curing deformation. ABAQUS was used to simulate the curing process of the composite ring. The results show a temperature gradient within the filament-wound layer. Thermo-chemical strain is similar between inner and outer regions. Total strain varies along the thickness due to mold constraint. Residual stress is governed by resin chemical shrinkage and thermal contraction during cooling. The difference between measured and simulated strain is 7.15%, which supports the validity of the multi-field coupled curing model. Full article