Search Results (941)

Shape-memory polymers (SMPs) are gaining significant attention for their ability to recover predefined shapes via external stimuli. Among thermally activated systems, biodegradable blends of polylactic acid (PLA) and polycaprolactone (PCL) are particularly promising for biomedical devices and soft actuators. This study develops a thermo-mechanical theoretical model to investigate the shape-memory behavior of a PLA/PCL composite blend under controlled thermal cycling. The framework integrates transient heat transfer, temperature-dependent elasticity, and viscoelastic dynamics to predict temperature evolution, deformation, and internal stress. The thermal response is computed via Newton’s law of convection, while the mechanical transition is described by a sigmoidal temperature- and crystallinity-dependent Young’s modulus. Beam bending theory is employed to evaluate the spatial distribution of strain and stress. A parametric sensitivity analysis was performed to evaluate the influence of different parameters, including the crystallinity grade, convective heat transfer coefficient, glass transition temperature, and viscoelastic recovery constant. The theoretical study accurately reproduces the shape-memory cycle, quantifying performance through fixation and recovery ratios. This model provides a robust tool for the rational design and optimization of biodegradable smart polymer structures. Full article

With the construction of transportation networks in mountainous areas under the Western Development Strategy, double-row pile foundations on slopes have been widely applied. However, due to the distortion of the soil stress field, their load distribution mechanism under bidirectional loading is extremely complex. To investigate the internal force distribution laws and deformation and failure modes, a systematic study was conducted utilizing theoretical derivation: 60 scale indoor physical model tests, and 3D refined finite element numerical simulations. The results show that the force distribution of double-row piles in slope environments differs significantly: the upper-row piles, affected by active earth pressure and sliding thrust, bear significantly higher load than the lower-row piles; meanwhile, the lower-row piles, constrained by stronger deep soil, can more fully utilize their vertical bearing capacity. Parametric analysis indicates that the terrain slope has a nonlinear amplification effect on the displacement difference at the pile top, with 50° being the critical mutation slope that triggers the failure of connection joints. In addition, the deformation mode of double-row piles undergoes a change when the pile spacing exceeds 5 times the pile diameter. Therefore, in practical engineering design, the traditional concept of symmetrical reinforcement should be abandoned in favor of differentiated bending reinforcement targeting the shallow surface layer of the upper-row piles and the deep inflection point of the lower-row piles. For working conditions with a slope greater than 50°, additional measures such as prestressed anchor cables must be applied to reduce the sliding load. Meanwhile, the row spacing should be strictly controlled within 5 times the pile diameter to fully ensure the diaphragm effect and the overall synergistic stability of the structure. Full article

Heterogeneous hydrogels capable of complex, programmable deformation are highly desirable for soft actuators, yet general strategies that simultaneously impart structural anisotropy, rapid responsiveness, and mechanical robustness remain limited. Here, a gradient anisotropic natural rubber-poly(N-isopropylacrylamide) (NR-PNIPAM) composite hydrogel is developed through a simple one-pot polymerization strategy by coupling pH-regulated colloidal stability with gravity-directed redistribution of natural rubber latex particles. Under an optimized pH window, NR nanoparticles gradually migrate during gelation and are fixed as a continuous gradient within the PNIPAM network, generating built-in structural asymmetry for nonuniform deformation. Meanwhile, NR nanoparticles act as soft reinforcing domains to improve mechanical strength, while water-soluble graphene nanosheets provide efficient photothermal conversion for remotely-controlled near-infrared (NIR)-responsive actuation. Benefiting from this synergistic design, the hydrogel exhibits programmable bending and localized folding with high actuation rates of 129° s⁻¹ and 46° s⁻¹, respectively, along with a tensile strength of 0.32 MPa and an active lifting capability exceeding 70 times its own weight. The material further enables biomimetic gripping and lifting under NIR stimulation. This work establishes a general route to robust gradient hydrogels by integrating colloidal regulation, structural anisotropy, and photothermal actuation, offering a versatile platform for high-performance soft intelligent systems. Full article

Copper (Cu) thin films and meshes on polyethylene terephthalate (PET) substrates are promising flexible transparent conductive electrodes (TCEs), yet their practical use is limited by insufficient interfacial adhesion and poor oxidative stability on inert polymer substrates. This work addresses these issues via a synergistic strategy of interfacial layer engineering and maskless laser lithography-based aperiodic mesh patterning, systematically comparing ceramic (Al₂O₃) and metallic (NiCr) interfacial layers for PET-supported Cu films and fabricating Linear/Sinusoidal aperiodic Cu meshes with tailored performance. Magnetron sputtering shows that Ar plasma-activated NiCr interfacial layers form a gradient-alloyed interface with Cu via interdiffusion, achieving 5B-level adhesion, mitigating bending-induced stress concentration, and enhancing damp-heat resistance (85 °C/85% RH) by suppressing oxidation—outperforming brittle Al₂O₃ layers. Patterning the optimized Cu/NiCr/PET structure into micrometer-scale meshes yields a Linear design with superior optoelectronic performance (~10.8 Ω/sq sheet resistance, >87% transmittance at 550 nm) and a Sinusoidal design with enhanced bending robustness via stress delocalization. Microstructural and elemental analyses clarify the NiCr layer’s interfacial toughening and anti-oxidation mechanisms. Practical validation in flexible transparent heaters demonstrates rapid thermal response and >20 h continuous operational stability. This study provides a scalable design strategy for high-performance PET-supported Cu meshes, offering insights for interface and structural optimization of flexible metallic TCEs for next-generation optoelectronics. Full article

Maize plant height and stalk mechanical strength are critical traits that influence planting density, yield, and lodging resistance. Although numerous dwarf mutants have been characterized in maize, most cannot be directly utilized in breeding programs due to associated developmental and reproductive deficiencies. In a previous study, we demonstrated that ZmNAC17 regulates mesocotyl elongation by mediating auxin and reactive oxygen species (ROS) biosynthetic pathways. Here, we characterize the role of ZmNAC17 in maize stalk development using both zmnac17 mutants and ZmNAC17-overexpressing (OE) lines. Plant height, stalk diameter, and internode length were reduced in both the zmnac17-1 EMS mutant and the zmnac17-3 CRISPR mutant. Internode cell length and cell area were decreased, whereas cell number was increased in zmnac17-1. Cellulose and lignin contents were elevated in zmnac17-1. Stalk bending force was diminished in zmnac17-3 but enhanced in the OE lines. The ratio of syringyl to guaiacyl (S/G), a key lignin monomer composition, was increased in zmnac17-3 while reduced in the OE lines. ZmNAC17 functions as a transcription factor, with its downstream targets implicated in phytohormone biosynthesis, phytohormone signaling, and lignin biosynthesis. CUT&Tag binding profile, EMSA, and dual-luciferase reporter assay demonstrate that ZmNAC17 promotes the expression of caffeoyl-CoA O-methyltransferase (CCoAOMT). IP-MS, Co-IP, and GST pull-down assays reveal that ZmNAC17 interacts with Beta glucosidase aggregating factor1 (BGAF1). Collectively, our findings indicate that ZmNAC17 regulates maize stalk development through transcriptional activation and protein–protein interactions, thereby providing new genetic resources for modifying plant architecture and mechanical strength in maize. Full article

Background/Objectives: Adolescent idiopathic scoliosis (AIS) is a multifactorial condition with an unclear etiology. Previous studies have reported associations of scoliosis with female sex, lower body mass index (BMI), and lower physical activity levels. This study examined factors associated with suspected scoliosis identified through school screening, with emphasis on BMI and sports participation. Methods: A cross-sectional study was conducted during the 2019/2020 school year and included 18,216 adolescents. Suspected scoliosis was identified using the forward bend test (FBT). Logistic regression analysis assessed associations between suspected scoliosis and sex, grade, BMI, participation in the seven most frequently reported sports, and training frequency. Results: Higher BMI (odds ratio (OR) = 0.91, p < 0.001), participation in soccer (OR = 0.64, p < 0.001), gymnastics (OR = 0.58, p = 0.05), martial arts (OR = 0.66, p = 0.02), and higher recreational training frequency (OR = 0.92, p < 0.001) were associated with lower odds of suspected scoliosis. Female sex (OR = 2.49, p < 0.001) and higher grade level (6th: OR = 1.54; 8th: OR = 2.98; p < 0.001) were associated with increased odds of suspected scoliosis. Conclusions: Suspected scoliosis identified through school screening was more frequently observed among females and adolescents with lower BMI. Participation in certain sports and greater recreational physical activity were associated with lower prevalence and odds of suspected scoliosis. These findings reflect screening-based associations and do not imply causal relationships. The results support the importance of school-based screening and consideration of body composition and physical activity patterns in the early identification of adolescents with suspected scoliosis. Full article

Additively manufactured cellular architectures frequently exhibit brittle failure under impact due to layer-induced stress concentrations. Through the programming of architectural and material design, specifically combining Fused Deposition Modeling (FDM) lattice topology with hyperelastic polyurea infiltration, this study achieves active control over the macroscopic transition from catastrophic structural fragmentation to stable progressive collapse. To evaluate this, auxetic and honeycomb specimens printed with ABS and glass-fiber-reinforced polyamide (PA-GF) were evaluated in unreinforced and polyurea-infiltrated states under quasi-static compression, three-point bending, and Charpy impact loading. Results show that the compressive response depends primarily on cellular topology; the pure auxetic (A-A) configuration provided the highest stiffness and energy absorption. Polyurea infiltration did not significantly alter elastic stiffness but increased post-yield stability, leading to a 96.6% elastic recovery in PA-GF A-A structures. In flexure, the base polymer governed stiffness, with ABS structures measuring 68% stiffer than PA-GF. Unreinforced ABS achieved 34% higher specific energy absorption (SEA) than PA-GF under compression, with the A-H topology maximizing SEA. Under dynamic impact, PA-GF absorbed an average of 70% more energy than ABS, and the H-A configuration recorded the highest impact resistance. The addition of polyurea shifted the failure mode from brittle fragmentation to stable elastomeric deformation, increasing absorbed impact energy by 52% for ABS and over 30% for PA-GF, preventing catastrophic structural failure. Integrating topological sequencing with elastomeric confinement provides a direct method to control energy dissipation and damage tolerance in 3D-printed cellular composites. Full article

Dissolution-induced spalling is a major deterioration mechanism affecting the long-term stability of grottoes exposed to acidic environments. However, existing numerical methods have limited capability in capturing the coupled effects of hydrochemical dissolution, joint degradation, and fracture propagation. In this study, a hydrochemical damage-coupled Discontinuous Deformation Analysis (DDA) method is proposed. A mineral dissolution-based crack evolution model is first established, and a chemical residual strength factor D_c is introduced to quantify the degradation of fracture toughness, tensile strength, and shear strength. The factor is then incorporated into a nonlinear joint constitutive model to simulate the mechanical-chemical behavior. The proposed method is validated through a two-block contact model and a three-point bending test. Results show that the model accurately reproduces nonlinear contact behavior, including stiffness degradation, hysteresis, and peak strength reduction (24.6% after 90 days) under chemical erosion. Further application to a typical sandstone grotto reveals a progressive failure process characterized by crack initiation, propagation, coalescence, and eventual block detachment. The results demonstrate that hydrochemical dissolution significantly accelerates structural degradation of grotto rock masses, and that both the number of active cracks as well as the total crack length have significantly increased. The proposed method provides an effective tool for evaluating long-term stability and supports the preservation of grotto cultural heritage. Full article

Organic memristive devices are promising components for neuromorphic systems. Although based on solution-processable materials, their fabrication often involves complex, resource-intensive processes. Here, we report the fabrication of organic memristive devices using aerosol jet printing to deposit both the active channel based on proprietary polyaniline-based bioink and PEDOT:PSS electrodes. Polymers printing has been carried out both on rigid and flexible substrates, the latter with the aim of demonstrating a flexible device not subjected to films delamination upon bending. By optimizing printing parameters, we achieved devices exhibiting high ON/OFF current ratios exceeding 100 and rapid switching dynamics, with performance comparable on glass and Kapton supports. Morphological and electrical characterizations revealed that channel thickness and uniformity critically influence resistive switching behavior. These findings demonstrate that aerosol jet printing enables scalable, low-material-consumption production of flexible organic memristive devices suitable for neuromorphic applications, potentially facilitating their integration into complex, energy-efficient bio-inspired circuits. Full article

This study analyzed the initial adsorption and activation of CO₂ on bimetallic Cu_nSc nanoclusters, with n = 3–7, using DFT calculations in ORCA with the r²SCAN-3c method. A total of 20 bare clusters and their corresponding Cu_nSc–CO₂ complexes were investigated, considering four structural configurations for each composition. To avoid classification based solely on adsorption energy, a global CO₂ activation index was developed and defined as IACO₂ = z(AG) + z(CTCO₂) + z(Bending) + z(ΔrC–O). In this index, AG = −ΔG_ads, CT_CO2 = −qCO₂, bending corresponds to (180° − ∠O–C–O), and (ΔrC–O) represents the average elongation of the C–O bonds. This descriptor enabled distinguishing complexes that only stabilize CO₂ from those that induce effective geometric and electronic activation. Although 5IV and 3IV exhibited favorable adsorption, with (ΔG_ads) values of −52.978 and −53.494 kcal mol⁻¹, respectively, their molecular activation was low, with nearly linear CO₂ and minimal or unfavorable charge transfer. In contrast, 7III and 7II showed the highest activation, with CT_CO2 values of 1.206 and 1.163, bending values of 69.867° and 68.869°, and C–O elongations of 0.208 and 0.195 Å, respectively. The standardized (IACO₂) ranking identified 7III, 7II, 3III, and 3II as the most relevant systems, with scores of 100.0, 93.8, 88.2, and 86.8, respectively. These results show that CO₂ activation on Cu_nSc nanoclusters should not be assessed solely by (ΔG_ads), but rather by a multi-criteria approach that accounts for stability, charge transfer, and molecular distortion. Full article

Background: Vitamin K2 (menaquinone) has been studied as a molecule with important effects on bone metabolism and has been proposed as a potential adjuvant in fracture healing, particularly under osteoporotic conditions. However, its functional impact on osteoporotic fracture healing remains largely undefined. The aim of this study was to evaluate the effects of vitamin K2 supplementation, in the form of menaquinone-4 (MK-4) and menaquinone-7 (MK-7), on fracture healing in an ovariectomized rat model of osteoporosis. Methods: Forty Wistar rats were included in this study and allocated to four equal groups: Sham control, ovariectomized control, MK-4, and MK-7. Osteoporosis was induced by bilateral ovariectomy, and 12 weeks after ovariectomy, a femoral fracture was produced and fixed by intramedullary nailing. Starting on postoperative day 2, the MK-4 group received 5 mg/kg/day of MK-4, while the MK-7 group received MK-7 at a dose of 0.05 mg/kg/day. Fracture healing was assessed primarily by biomechanical testing using a three-point bending test and was further analyzed by histological and biochemical parameters, including CTXI, PINP, ucOC, BALP, and ALT. Results: Vitamin K2 supplementation did not improve functional fracture healing. In both treatment groups, fractures showed nonunion-like mechanical behavior, precluding meaningful quantitative biomechanical comparison. Although histological and biochemical findings, particularly in the MK-4 group, showed some degree of biological activity, these changes did not translate into mechanically competent bone union. Both treatment groups showed a tendency toward impaired healing, with progression toward nonunion-like behavior under the present experimental conditions. No significant hepatic toxicity was observed. Conclusions: In this ovariectomized rat femoral fracture model, vitamin K2 supplementation with either MK-4 or MK-7 did not enhance functional fracture healing despite evidence of biological activity of the treatment. These findings suggest a discrepancy between molecular or histological effects and biomechanical outcomes, indicating that, under the conditions tested, vitamin K2 is insufficient to overcome impaired healing in osteoporotic bone and may adversely influence fracture repair under these experimental conditions, although the mechanism remains uncertain. Full article

This study investigated the pollution characteristics, ecological risks, and sources of six trace elements in the water, riparian soils, and benthic sediments of the Taohuajiang lead–zinc mining area, Guangxi. Water, soil, and sediment samples were evaluated using pollution indices and source apportionment models. The results show zinc (Zn) is the primary water pollutant, spatially correlated with mining sites. Conversely, both soils and sediments exhibit severe composite contamination, with cadmium (Cd), lead (Pb), Zn, and silver (Ag) significantly exceeding background values. Notably, sediment trace elements accumulate intensely downstream of the mining zone and at river meander bends driven by hydrodynamic deposition. The area is classified as an extremely high risk zone (mean ecological risk index > 1200), predominantly driven by Cd. Source apportionment identified three factors governing the soils and sediments: legacy mining constitutes the principal source of Pb, Zn, Cd, Ag, and copper (Cu); natural geological processes govern arsenic (As); and agricultural/domestic activities partially contribute to Cu and Ag. Overall, historical mining primarily drives the regional contamination across multi-phase media, which is further exacerbated by agriculture, collectively threatening the local benthic and terrestrial ecosystem. Full article

Accurate and unobtrusive measurement of upper-limb kinematics is critical for advancing wearable sensing technologies used in industrial ergonomics, human–machine interaction, and real-time biomechanics monitoring. This study evaluates the performance of two soft, flexible wearable sensors—BendLabs biaxial angular displacement sensors and StretchSense capacitive stretch sensors—for quantifying wrist and elbow motions during simulated dynamic industrial tasks. Wrist flexion–extension and radial–ulnar deviation were measured using BendLabs sensors mounted on the dorsal hand, while elbow flexion–extension was captured using StretchSense sensors positioned along the elbow joint. A multi-camera optical motion capture system served as the reference standard. Sensor data were preprocessed using baseline correction, smoothing, denoising, and normalized cross-correlation techniques to support temporal alignment with motion-capture recordings. Across all activities, the BendLabs sensors demonstrated moderate agreement with motion capture for wrist kinematics, with generally better performance for radial–ulnar deviation than for flexion–extension. StretchSense sensors demonstrated stronger agreement with motion capture for elbow flexion–extension, with performance that was generally consistent across task types. These findings support the feasibility of soft wearable sensors for capturing upper-limb kinematics during simulated occupational tasks and highlight their potential for integration into ergonomic assessment, occupational monitoring systems, and future industrial wearable platforms. Full article

Bending actuators are key components in soft robotics and other engineering applications where compact, reversible, and biomimetic motion is required. Although many bending actuators have been identified, the literature remains fragmented, with most studies organized by material type, activation principle, or application domain. This review adopts a configuration-based perspective and classifies bending actuators by geometric architecture rather than by actuation technology. Representative actuators from the literature were analyzed and grouped according to geometric mechanisms that convert input energy into curvature. The analysis reveals that diverse actuator technologies repeatedly rely on a set of recurring configuration families, including laminated, tubular, internal chambers, rolled, origami/kirigami, articulated, and hybrid structures. By emphasizing geometry, the proposed taxonomy clarifies the structural origins of bending motion and enables cross-technology comparison of bending actuators. Full article

An efficient hybrid modeling framework is developed for the dynamic analysis of offshore wind turbines (OWTs) by coupling an aero–servo–elastic rotor–nacelle superelement with a hydroelastic substructure. The complex rotor–nacelle dynamics are condensed into a reduced-order 14-DOF representation through a modal-based multibody formulation, while retaining blade deformation, spinning effects, nonlinear aerodynamic loading, and active servo controls. Its interface compatibility at the nacelle enables the coupling with either numerical or physical substructures, establishing a unified basis for system hybrid formulation, co-simulations, and real-time hybrid simulations. The validity of the superelement is verified by comparing the resulting fully coupled modal model against OpenFAST, demonstrating high consistency in time-domain responses. As a demonstration, the verified superelement is further coupled with a 1D finite element model of the supporting structure (tower–monopile substructure) to form a hybrid model, enabling accurate force analysis of the OWT structure. Dynamic analyses of the IEA 10 MW OWT reveal that while the blade flapwise responses and the operation-related edgewise responses are 1P-dominated, tower side–side responses and idling-related tower fore–aft and blade edgewise responses manifest at their corresponding resonance frequencies. The maximum displacement and maximum bending moment envelopes vary monotonically with height. Instead, the maximum stress envelope possesses high values in the mid-lower sections of the tower. This high-stress region undergoes a spatial shift driven by the blade feathering mechanism. Full article