Search Results (297)

Metallic nanofoams with amorphous structures demonstrate exceptional properties and significant potential for diverse applications. However, their mechanical properties at different temperatures are still unclear. By using molecular dynamics simulation, this study investigates the mechanical responses of representative CuZr amorphous metallic nanofoam (AMNF) under uniaxial tension and compression at various temperatures. Our results reveal that the mechanical properties, such as Young’s modulus, yield stress, and maximum stress, exhibit notable temperature sensitivity and tension–compression asymmetry. Under tensile loading, the Young’s modulus, yield strength, and peak stress exhibit significant reductions of approximately 30.5%, 33.3%, and 32.9%, respectively, as the temperature increases from 100 K to 600 K. Similarly, under compressive loading, these mechanical properties experience even greater declines, with the Young’s modulus, yield strength, and peak stress decreasing by about 34.5%, 38.0%, and 41.7% over the same temperature range. The tension–compression asymmetry in yield strength is temperature independent. Interestingly, the tension–compression asymmetry in elastic modulus becomes more pronounced at elevated temperatures, which is attributed to the influence of surface energy effects. This phenomenon is further amplified by the increased disparity in surface-area-to-volume ratio variations between tensile and compressive loading at higher temperatures. Additionally, as the temperature rises, despite material softening, the structural resistance under large tensile strains improves due to delayed ligament degradation and more uniform deformation distribution, delaying global failure. Full article

Potassium is the most abundant macronutrient in plants, participating in essential physiological processes such as turgor maintenance. A reduction in cell turgor is a hallmark of the ripening process associated with fruit softening. The dynamic of K⁺ fluxes in fleshy fruits is largely unknown; however, the reallocation of K⁺ into the apoplast has been proposed as a contributing factor to the decrease in fruit turgor, contributing to fruit softening. High-affinity K⁺ transporters belonging to the KUP/HT/HAK transporter family have been implicated in this process in some fruits. In this study, a comprehensive genome-wide analysis of the KUP/KT/HAK family of high-affinity K⁺ transporters in strawberry (Fragaria × ananassa Duch.) was conducted, identifying 60 putative transporter genes. The chromosomal distribution of the FaKUP gene family and phylogenetic relationship and structure of predicted proteins were thoroughly examined. Transcriptomic profiling revealed the expression of 19 FaKUP genes within the fruit receptacle, with a predominant downregulation observed during ripening, particularly in FaKUP14, 24 and 47. This pattern suggests their functional relevance in early fruit development and turgor maintenance. Mineral composition analyses confirmed that K⁺ is the most abundant macronutrient in strawberry fruits, exhibiting a slight decrease as ripening progressed. Membrane potential (E_m) and diffusion potentials (E_D) at increasing external K⁺ concentrations were measured by electrophysiology in parenchymal cells of green and white fruits. The results obtained suggest a significant diminution in cytosolic K⁺ levels in white compared to green fruits. Furthermore, the slope of change in E_D at increasing external K⁺ concentration indicated a lower K⁺ permeability of the plasma membrane in white fruits, aligning with transcriptomic data. This study provides critical insights into the regulatory mechanisms of K⁺ transport during strawberry ripening and identifies potential targets for genetic modifications aimed at enhancing fruit firmness and shelf life. Full article

In order to solve various problems in traditional roads and extend their service life, new road materials have become a research hotspot. Polyurethane prepolymers (PUPs) and ceramic fibers (CFs), as materials with unique properties, were chosen due to their synergistic effect: PUPs provide elasticity and gel-like behavior, while CFs contribute to structural stability and high-temperature resistance, making them ideal for enhancing asphalt performance. PUPs, a thermoplastic and elastic polyurethane gel material, not only enhance the flexibility and adhesion properties of asphalt but also significantly improve the structural stability of composite materials when synergistically combined with CF. Using response surface methodology, an optimized preparation scheme for PUP/CF composite-modified asphalt was investigated. Through aging tests, dynamic shear rate (DSR) testing, bending rate (BBR) testing, microstructure scanning (MSCR), scanning electron microscopy (SEM), atomic force microscopy (AFM), and infrared spectroscopy (IR), the aging performance, rheological properties, permanent deformation resistance, microstructure, and modification mechanism of PUP/CF composite-modified asphalt were investigated. The results indicate that the optimal preparation scheme is a PUP content of 7.4%, a CF content of 2.1%, and a shear time of 40 min. The addition of the PUP and CF significantly enhances the asphalt’s aging resistance, and compared with single-CF-modified asphalt and base asphalt, the PUP/CF composite-modified asphalt exhibits superior high- and low-temperature rheological properties, demonstrating stronger strain recovery capability. The PUP forms a gel network structure in the material, effectively filling the gaps between CF and asphalt, enhancing interfacial bonding strength, and making the overall performance more stable. AFM microscopic morphology shows that PUP/CF composite-modified asphalt has more “honeycomb structures” than matrix asphalt and CF-modified asphalt, forming more structural asphalt and enhancing overall structural stability. This study indicates that the synergistic effect of PUP gel and CF significantly improves the macro and micro properties of asphalt. The PUP forms a three-dimensional elastic gel network in asphalt, improving adhesion and deformation resistance. Using response surface methodology, the optimal formulation (7.4% PUP, 2.1% CF) improves penetration (↓41.5%), softening point (↑6.7 °C), and ductility (↑9%), demonstrating the relevance of gel-based composites for asphalt modification. Full article

Background/Objectives: This study investigates the impact of high humidity (25 °C, 75% relative humidity) on gelatin and hydroxypropyl methylcellulose (HPMC) capsules used in dry powder inhalers (DPIs), focusing on moisture dynamics, structural responses, and mechanical performance, with an emphasis on understanding how different capsule types respond to prolonged exposure to humid conditions. Methods: Capsules were exposed to controlled humidity conditions, and moisture uptake was measured via thermal analysis. Visual observations of silica bead color changes were performed to assess moisture absorption, while surface wettability was measured using the sessile drop method. Hardness testing, mechanical deformation, and puncture tests were performed to evaluate structural and mechanical changes. Positron annihilation lifetime spectroscopy (PALS) was used to analyze free volume expansion. Results: HPMC capsules exhibited rapid moisture uptake, attributed to their lower equilibrium moisture content and ability to rearrange dynamically, preventing brittleness. In contrast, gelatin capsules showed slower moisture absorption but reached higher equilibrium levels, resulting in plasticization and softening. Mechanical testing showed that HPMC capsules retained structural integrity with minimal deformation, while gelatin capsules became softer and exhibited reduced puncture resistance. Structural analysis revealed greater free volume expansion in HPMC capsules, consistent with their amorphous nature, compared with gelatin’s semi-crystalline matrix. Conclusions: HPMC capsules demonstrated superior humidity resilience, making them more suitable for protecting moisture-sensitive active pharmaceutical ingredients (APIs) in DPI formulations. These findings underline the importance of appropriate storage conditions, as outlined in the Summary of Product Characteristics, to ensure optimal capsule performance throughout patient use. Full article

USP (usual temperature pitch)-modified asphalt optimizes its rheological properties through reactions between the modifier and the asphalt. This significantly enhances the high- and low-temperature adaptability and environmental friendliness of asphalt. It has now become an important research direction in the field of highway engineering. This article systematically investigates the impact of different dosages of USP warm mix modifier on asphalt binders through rheological and microstructural analysis. Base asphalt and SBS-modified asphalt were blended with USP at varying ratios. Conventional tests (penetration, softening point, ductility) were combined with dynamic shear rheometry (DSR, AASHTO T315) and bending beam rheometry (BBR, AASHTO T313) to characterize temperature/frequency-dependent viscoelasticity. High-temperature performance was quantified via multiple stress creep recovery (MSCR, ASTM D7405), while fluorescence microscopy and FTIR spectroscopy elucidated modification mechanisms. Key findings reveal that (1) optimal USP thresholds exist at 4.0% for base asphalt and 4.5% for SBS modified asphalt, beyond which the rutting resistance factor (G*/sin δ) decreases by 20–31% due to plasticization effects; (2) USP significantly improves low-temperature flexibility, reducing creep stiffness at −12 °C by 38% (USP-modified) and 35% (USP/SBS composite) versus controls; (3) infrared spectroscopy displays that no new characteristic peaks appeared in the functional group region of 4000–1300 cm⁻¹ for the two types of modified asphalt after the incorporation of USP, indicating that no chemical changes occurred in the asphalt; and (4) fluorescence imaging confirmed that the incorporation of USP led to disintegration of the spatial network structure of the control asphalt, explaining the reason for the deterioration of high-temperature performance. Full article

In this paper, the low-cycle fatigue deformation behavior of polycrystalline γ-TiAl alloys at different temperatures was investigated by molecular dynamics simulations. The results showed that the fatigue process comprises an initial cyclic softening stage followed by saturation, and the stress–strain response of the material shows significant asymmetry. With an increase in temperature, the asymmetry between tensile and compressive stresses gradually decreases, and the amplitude of saturated stress decreases significantly. The decrease in dislocation density leads to the cyclic softening of the alloy, and the evolution of dislocation density is temperature-dependent. The dislocation density first decreases and then tends to be stable, while at 900 °C and 1000 °C, it shows an abnormal trend of decreasing first and then increasing. In addition, microscopic mechanism analysis shows that grain coarsening, dislocation annihilation, and phase instability lead to the cyclic softening of the alloys. The fatigue plastic accumulation at low temperatures is mainly dominated by dislocation slip, while at high temperatures, grain boundary slip gradually replaces dislocation slip and becomes the main deformation mechanism. This work reveals new insights into the mechanical behavior of polycrystalline γ-TiAl alloys under cyclic plasticity and temperature-dependent deformation mechanisms. Full article

A hot compression simulation was conducted on the Al-7.62Zn-2.22Mg-0.90Cu-0.30Mn-0.09Er-0.13Zr alloy (7E97) within the temperature range of 300~460 °C and strain rate range of 0.001~10 s⁻¹ using a Gleeble-3500 hot simulator. A flow-stress constitutive equation and hot processing maps were established for the alloy, and the microstructural evolution of the alloy after hot deformation was investigated. It was found that the dominant dynamic softening mechanism of the alloy was dynamic recovery, accompanied by minor dynamic recrystallization. The optimal hot processing window for the alloy was determined to be in the ranges of 0.001~0.05 s⁻¹ and 350~410 °C. Full article

The metallic shaped charge liner (SCL) is widely utilized in the defense industry, oil perforation, cutting, and other industrial fields due to the powerful penetration performance. However, quantitative law and underlying mechanisms of material properties affecting SCL penetration performance are unclear. Based on the real and virtual material properties, by combining numerical simulation with machine learning, the influence of material properties on SCL penetration performance was systematically studied. The findings in the present work provided new insights into the penetration mechanism and corresponding influencing factors of the metal jet. It indicated that penetration depth was dominated by the melting point, specific heat, and density of the SCL materials rather than the conventionally perceived plasticity and sound velocity. Average perforation diameter was dominated by the density and plasticity of the SCL materials. Particularly, the temperature rise and thermal softening effect of the SCL controlled by the melting point and specific heat have a significant effect on the “self-consumption” of the metal jet and further on the penetration ability. Additionally, the density of the SCL influences the penetration depth deeply via dynamic pressure of the jet, but the influence of density on penetration depth decreases with the increase in density. The correlation between the key properties and penetration performance was obtained according to a quadratic polynomial regression algorithm, by which the penetration potential of SCL materials can be quantitatively evaluated. Overall, the present study provides a new SCL material evaluation and design method, which can help to expand the traditional penetration regime of the SCL in terms of the penetration depth and perforation and is expected to be used for overcoming the pierced and lateral enhancement trade-off. Full article

The use of composite materials within extreme environments is an exciting frontier in which a wealth of cutting-edge developments have taken place recently. Although there is vast knowledge of composites’ behaviour in standard room temperature and humidity, there is a great need to understand their performance in ‘hot/wet’ conditions, as these are the conditions of their envisaged applications. One of the key failure mechanisms within composites is interlaminar fracture, commonly referred to as delamination. The environmental effects of moisture and elevated temperatures on interlaminar fracture toughness are therefore essential design considerations for laminated aerospace-grade composite materials. IM7/8552, a toughened epoxy/carbon fibre reinforced polymer, was experimentally characterised in both ‘Dry’ and ‘Wet’ conditions at 23 °C and 90 °C. A moisture uptake study was conducted during the ‘Wet’ conditioning of the material in a 70 °C/85% relative humidity environment. Dynamic mechanical thermal analysis was carried out to determine the effect of moisture on the glass transition temperature of the material. Mode I initiation and propagation fracture properties were determined using double cantilevered beam specimens and Mode II initiation fracture properties were deduced using end-notched flexure specimens. The effects of precracking and the methodology of high-temperature testing are discussed in this report. Mode I interlaminar fracture toughness, $G_{IC}$, was found to increase with elevated temperatures and moisture content, with $G_{IC}=0.205{\mathrm{kJ}/\mathrm{m}}^2$ in ‘Dry 23 °C’ conditions increasing by 26% to $G_{IC}=0.259{\mathrm{kJ}/\mathrm{m}}^2$ in ‘Wet 90 °C’ conditions, demonstrating that the material exhibited its toughest behaviour in ‘hot/wet’ conditions. Increased ductility due to matrix softening and fibre bridging caused by temperature and moisture were key contributors to the elevated $G_{IC}$ values. Mode II interlaminar fracture toughness, $G_{IIC}$, was observed to decrease most significantly when moisture or elevated temperature was applied individually, with the combination of ‘hot/wet’ conditions resulting in an 8% drop in $G_{IIC}$, with $G_{IIC}=0.586{\mathrm{kJ}/\mathrm{m}}^2$ in ‘Dry 23 °C’ conditions and $G_{IIC}=0.541{\mathrm{kJ}/\mathrm{m}}^2$ in ‘Wet 90 °C’ conditions. The coupled effect of fibre-matrix interface degradation and increased plasticity due to moisture resulted in a relatively small knockdown on $G_{IIC}$ compared to $G_{IC}$ in ‘hot/wet’ conditions. Fractographic studies of the tested specimens were conducted using scanning electron microscopy. Noteworthy surface topography features were observed on specimens of different fracture modes, moisture saturation levels, and test temperature conditions, including scarps, cusps, broken fibres and river markings. The qualitative features identified during microscopy are critically examined to extrapolate the differences in quantitative results in the various environmental conditions. Full article

A hot compression test was conducted across a range of temperatures (350, 400, 450, and 500 °C) and varying strain rates (0.001–10 s⁻¹) to explore the hot compression behavior of the 6063 alloy. Hot processing maps were obtained based on the stress–strain curves. Optimal processing parameters were identified as residing within the intervals of (470–500 °C, 0.01–0.1108 s⁻¹), achieving a maximum dissipation efficiency of 0.4, which is of great importance for perfecting hot processing. The microstructure evolution was characterized using an optical microscope and a transmission electron microscope. The initial grains were elongated under compressive deformation, and the density of dislocation rose with increasing strain rate and decreasing temperature. Dynamic recovery serves as the main dynamic softening mechanism during hot compression. Full article

For investigating the effect of temperature and strain rate on martensitic transformation and establishing the corresponding kinetic model for newly TRIP (transformation-induced plasticity) aided duplex stainless steel (DSS), the tensile tests are conducted at temperatures of 20–150 °C and strain rates of 0.0001–150 s⁻¹. The stepped cross-section tensile specimen is proposed and designed for obtaining microstructure at specific strain during dynamic tensile testing. The results demonstrate that the deformation mechanism of austenite in TRIP-aided DSS is highly sensitive to temperature and strain rate. As the deformation temperature increases, strain-induced martensitic transformation is inhibited, and the deformation mechanism transforms from martensitic transformation to the co-occurrence of martensitic transformation and twinning, and finally, twinning is the main deformation mechanism. This leads to reduced strength with an initial increase followed by a decrease in elongation. As the strain rate increases, martensitic transformation is inhibited, resulting in a reduction in strength and plasticity during quasi-static tensile testing, while during dynamic tensile testing, strength increases due to enhanced resistance to dislocation motion, and plasticity displays no significant variation because of the combination of adiabatic softening and martensitic transformation suppression. Moreover, during tensile deformation, a plastic temperature rise model is established for newly developed DSSs. Based on this model, the Ludwigson–Berger model for martensitic transformation was modified to couple the effect of temperature and strain rate by considering the non-uniform distribution of temperature rise within the material and its variation with strain rate, as well as the suppression of dynamic strain rate on martensitic transformation. This new model could accurately describe the characteristics of martensitic transformation in newly developed DSSs at different deformation temperatures and strain rates. Full article

Various high-throughput screening methods have been developed to explore plant phenotypes, primarily at the organ and whole plant levels. There is a need to develop phenomics methods at the cellular level to narrow down the genotype to phenotype gap. This study used double-resonator piezoelectric cytometry biosensors to capture the dynamic changes in mechanical phenotypes of living cells of two rice species, drought-resistant Lvhan No. 1 and drought-sensitive 6527, under PEG6000 drought stress. In rice cells of Lvhan No. 1 and 6527, mechanomics parameters, including cell-generated surface stress (ΔS) and viscoelastic parameters (G′, G″, G″/G′), were measured and compared under 5–25% PEG6000. Lvhan No. 1 showed larger viscoelastic but smaller surface stress changes with the same concentration of PEG6000. Moreover, Lvhan No. 1 cells showed better wall–plasma membrane–cytoskeleton continuum structure maintaining ability under drought stress, as proven by transient tension stress (ΔS > 0) and linear G′~ΔS, G″~ΔS relations at higher 15–25% PEG6000, but not for 6527 cells. Additionally, two distinct defense and drought resistance mechanisms were identified through dynamic G″/G′ responses: (i) transient hardening followed by softening recovery under weak drought, and (ii) transient softening followed by hardening recovery under strong drought. The abilities of Lvhan No. 1 cells to both recover from transient hardening to softening and to recover from transient softening to hardening are better than those of 6527 cells. Overall, the dynamic mechanomics phenotypic patterns (ΔS, G′, G″, G″/G′, G′~ΔS, G″~ΔS) verified that Lvhan No. 1 has better drought resistance than that of 6527, which is consistent with the field data. Full article

The physico-mechanical properties of date fruit varieties can indicate their quality and freshness. These properties, which include firmness, moisture content, and mechanical resistance, are closely linked to the fruit’s overall quality and can be used to assess its ripeness and suitability for consumption. Therefore, the current study evaluated the physico-mechanical properties of three date varieties—Sukkari, Khalas, and Saqie—across different ripening stages to enhance food quality and optimize postharvest handling. The study uniquely focused on how ripening stages affect the stress–strain behavior of dates, offering new insights into their mechanical resistance, deformability, and structural stability, all of which are critical parameters for maintaining food quality during storage, transportation, and processing. Significant changes in physical characteristics, including size, mass, moisture content, and density, were observed as the fruit progressed through ripening stages. Sukkari showed the most notable decrease in moisture content, from 61.8% at the Khalal stage to 17.3% at the Tamar stage, resulting in softening and reduced mechanical resistance, potentially impacting shelf life and consumer acceptance. Khalas exhibited a more gradual decline in mechanical properties, with moisture content dropping to 24.6%. At the same time, Saqie demonstrated minimal changes in mechanical properties and moisture content, suggesting better structural and nutritional quality retention. Additionally, the dynamic coefficient of friction increased with temperature and pressure at the Tamr stage, with Sukkari showing the highest values (up to 0.496), followed by Khalas (up to 0.451) and Saqie (up to 0.406). This study introduced the concept of variety-specific differences in frictional behavior, providing valuable insights for improving mechanical processing, reducing physical damage, and preserving date fruits’ nutritional and sensory quality. In conclusion, findings highlight the importance of variety-specific mechanical profiling in improving processing protocols, reducing postharvest losses, and maintaining the nutritional and sensory quality of date fruits for industrial-scale operations. Full article

Expansive soils have significant characteristics of expansion by water absorption, contraction by water loss. Under the freeze–thaw (F-T) cycles, the engineering diseases are more significant, and the serious geotechnical engineering incidents are induced extremely easily. The aim is to investigate the mechanical response characteristics of geogrid-reinforced expansive soils (GRES) under F-T cycles. Based on a series of large-scale temperature-controlled triaxial tests, influencing factors were considered, such as the number of F-T cycles, the geogrid layers, and the confining pressure. The results showed that: (1) Friction between the expansive soil and geogrid and the geogrid’s embedded locking effect indirectly provided additional pressure, limited shear deformation. With the increase in reinforced layers, the stress–strain curve changed from a strain-softening to a strain-hardening type. (2) Elastic modulus, cohesion, and friction angle decreased significantly with increasing number of F-T cycles, whereas dynamic equilibrium was reached after six F-T cycles. (3) The three-layer reinforced specimens showed the best performance of F-T resistance, compared to the plain soil, the elastic modulus reduction amount decreases from 35.7% to 18.3%, cohesion from 24.5% to 14.3%, and friction angle from 7.6% to 4.5%. (4) A modified Duncan–Zhang model with the confining pressure, the F-T cycles, and the geogrid layers was proposed; the predicted values agreed with the measured values by more than 90%, which can be used as a prediction formula for the stress–strain characteristics of GRES under freeze–thaw cycling conditions. The research results can provide important theoretical support for the practical engineering design of GRES in cold regions. Full article

During deep mining engineering, coal bodies are subjected to complex geological stresses such as periodic roof pressure and blasting impacts, which may induce mechanical property deterioration and trigger severe rock burst accidents. This study systematically investigated the mechanical characteristics and failure mechanisms of coal under strain rates on two orders of magnitude through quasi-static cyclic loading–unloading experiments and split Hopkinson pressure bar (SHPB) tests, combined with acoustic emission (AE) localization and crack characteristic stress analysis. The research focused on the differential mechanical responses of coal-rock masses under distinct stress environments in deep mining. The results demonstrated that under quasi-static loading, the stress–strain curve exhibited four characteristic stages: compaction (I), linear elasticity (II), nonlinear crack propagation (III), and post-peak softening (IV). The peak strain displayed linear growth with increasing cycle, accompanied by a failure mode characterized by oblique shear failure that induced a transition from gradual to abrupt increases in the AE counts. In contrast, under the dynamic loading conditions, there was a bifurcated post-peak phase consisting of two unloading stages due to elastic rebound effects, with nonlinear growth of the peak strain and an interlaced failure pattern combining lateral tensile cracks and axial compressive fractures. The two loading conditions exhibited similar evolutionary trends in crack damage stress, though a slight reduction in stress occurred during the final dynamic loading phase due to accumulated damage. Notably, the crack closure stress under quasi-static loading followed a decrease–increase pattern with cycle progression, whereas the dynamic loading conditions presented the inverse increase–decrease tendency. These findings provide theoretical foundations for stability control in underground engineering and prevention of dynamic hazards. Full article