Search Results (610)

Flexible and stretchable electronics inevitably undergo stretching, compression, bending and torsion when conformally attached to skin, soft tissues and dynamic organs. While deformation-induced electrical variations act as target signals for motion sensors, they cause resistance/impedance drift, baseline shift and sensitivity degradation in physiological electrodes, temperature/chemical sensors, interconnects and stimulation devices, leading to motion artifacts and reduced long-term reliability. Hydrogels are pivotal materials for soft bioelectronic interfaces owing to their high water content, low modulus, tissue compatibility and ionic conductivity. However, their conductive networks are susceptible to structural reconstruction under deformation, dehydration, swelling and cyclic fatigue, meaning that stretchability is by no means equivalent to strain insensitivity. This review focuses on stable resistance/impedance and functional output within a specified strain window, this paper reviews three representative material systems, liquid metal (LM)-based composite hydrogels, conductive polymer/elastic network composite hydrogels, and hydrogen-bonded isotropic architectures. It further summarizes three design strategies—geometric and functional compensation, mechanical decoupling and strain isolation, and interfacial engineering for conductive network stabilization—and discusses their applications in wearable epidermal and implantable bioelectronics. Finally, unified evaluation metrics for strain insensitivity are proposed, with future directions covering high-conductivity–low-modulus synergy, long-term water/ionic stability, robust soft-hard interfaces, multiaxial deformation tolerance and scalable manufacturability. Full article

The legs of flying insects play a critical role in enabling seamless transitions between aerial and terrestrial environments. These appendages serve multiple functions, including landing, walking, jumping, and transitioning from jumping to flight (takeoff). Such capabilities have inspired engineers to seek similar multimodal mechanisms in Flapping-Wing Aerial Robots (FWARs) to expand their operational versatility across diverse environments. However, designing multimodal mechanisms with distinct kinematic and propulsive characteristics remains challenging, particularly in the domain of autonomous jump takeoff for FWARs, where research remains relatively sparse. In this study, inspired by the jumping takeoff strategy and hindleg kinematics of the Asian migratory locust (Locusta migratoria), we propose a functional bio-inspired jumping takeoff mechanism that extracts selected mechanical principles of the locust jumping system, including elastic energy accumulation, temporary mechanical locking, and rapid energy release. The mechanism employs a gear–crank–slider transmission system and utilizes one-way bearings to regulate the locking and disengaging states, enabling the storage and rapid release of energy for jump takeoff, thereby achieving autonomous takeoff of the robot. Adams dynamic simulations show that at a torsion spring angle of 40°, the mechanism achieves a maximum resultant velocity of 1.955 m/s, a jump height of 168.2 mm, and a horizontal displacement upon landing of 134.6 mm. Ansys Fluent (2024 R2) simulations under multiple operating conditions further confirm that the aerodynamic performance is optimal at a takeoff angle of attack(α) of 5° with a torsion spring angle(β) of 40°, yielding a lift-to-drag ratio of 3.005. This work presents a functional bio-inspired jumping takeoff mechanism based on selected mechanical principles of locust jumping, providing a potential approach for improving the autonomous takeoff capability of small-scale FWARs. Full article

This study investigates the under-explored contribution of internal radial stress to macroscopic gravitational potentials. We utilize a novel, precision-damped torsion balance apparatus designed to isolate and measure gravitational perturbations induced by radial stress within rapidly rotating macroscopic masses, rigorously controlling for acoustic, thermal, and electromagnetic variables. Our findings document an anisotropic mechanical influence along the plane of rotation that exceeds standard weak-field gravitational predictions. The measured apparatus potential exhibits a kinematic scaling ($\propto {\omega }^4$) consistent with a linear torsion spring responding to an underlying quadratic (${\omega }^2$) driving force. While active Herzan leveling, counter-rotating geometry, and precision balancing successfully eliminated bulk frame-drag and mechanical vibration, this atmospheric baseline study concedes that the persistent ${\omega }^2$ force may still be masked by complex, non-linear fluid dynamic asymmetries. Consequently, this paper establishes a ‘Stage 1’ methodological baseline, mapping the absolute limits of atmospheric testing and defining the engineering prerequisites for future high-vacuum gravitational extractions. Isolating this residual force in a future high-vacuum environment is imperative. Should such testing confirm the signal is gravitationally sourced, this anisotropy suggests a potential coupling between the internal stress-energy tensor and the local spacetime metric that is not fully accounted for in standard linear approximations. If this phenomenological stress-metric coupling can be isolated and shown to scale macroscopically, it could theoretically provide a non-linear mechanism for observed rotational gravitational symmetry breaking. The speculative astrophysical implications of such a coupling are also discussed. Full article

Eccentric reaming tools are widely integrated into bottom-hole assemblies during while-drilling reaming operations to improve borehole quality and enhance drilling-assembly passability. However, their eccentric geometry introduces periodic tool–borehole contact, friction, and impact excitations, which may adversely affect the dynamic stability of the drilling system. In this study, a process-oriented finite element dynamic model of a bottom-hole assembly incorporating a bidirectional eccentric reaming tool was developed to investigate coupled radial, axial, and torsional vibration responses under different stabilizer configurations. Three configurations, namely the near-bit, single-stabilizer, and double-stabilizer configurations, were systematically compared. The results indicate that the double-stabilizer configuration produces the most continuous and regular annular borehole profile and promotes a more stable tool–borehole contact state. Compared with the other configurations, it provides stronger lateral constraint, yields the lowest radial-displacement fluctuations, reduces radial and axial acceleration responses, and mitigates longitudinal impacts. The near-bit configuration exhibits the most pronounced torsional instability, including transient reverse rotation of the reaming tool, whereas no reverse rotation occurs under the double-stabilizer configuration. An orthogonal design was further conducted to optimize the operating parameters. Range analysis shows that rotational speed has a greater influence on the radial-displacement root-mean-square value than weight on bit within the investigated parameter range. The optimal operating condition was identified as a rotational speed of 50 rpm and a weight on bit of 80 kN. These findings demonstrate that bilateral stabilizer support can improve borehole regularity, suppress coupled vibration, and enhance the operational stability of while-drilling eccentric reaming systems. Full article

This study evaluates the post-earthquake damage of a 17-story plan-irregular reinforced concrete (RC) building damaged during the 2024 Hualien earthquake. A three-dimensional numerical model was constructed in ETABS, utilizing nonlinear component characteristics derived from the mechanics-based Seismic Evaluation of RC Building (SERCB) framework to execute nonlinear dynamic time-history analysis (NDTHA). The actual triaxial ground motion records from the 3 April 2024 earthquake were applied as the seismic input. To correlate analytical outcomes with physical seismic damage, a displacement-based ductility development index (D) was adopted to quantitatively associate simulated plastic hinge responses with field-observed damage states ranging from Slight (DS I) to Collapse (DS V). Post-earthquake reconnaissance revealed that structural damage was primarily concentrated in the perimeter RC shear walls between the 1st and 6th stories. The predicted wall damage states spanned from Moderate (DS II) to Severe (DS IV), whereas the primary beam–column frame exhibited only Slight damage (DS I). Quantitative comparison demonstrates exact damage state match rates of 63.6% (7/11) for Frame 1 and 71.4% (5/7) for Frame 2, with all remaining discrepancies bounded within a minor one-class margin. These analytical results show high consistency with field observations, confirming that NDTHA incorporating SERCB-based plastic hinge modeling can effectively reproduce the nonlinear seismic behavior and localized damage distribution of torsionally irregular RC structures. The findings extend traditional laboratory-scale component validation to full-scale building damage reconnaissance, providing robust empirical evidence for cross-validating physical seismic damage against dynamic simulation predictions. Full article

This study presents a multi-methodological approach combining subsurface characterization with dynamic structural assessment to evaluate Soil–Structure Interaction (SSI) mechanisms at the Palazzo Centrale. The 3D Electrical Resistivity Tomography (ERT) and active Multichannel Analysis of Surface Waves (MASW) results were compared with a lithostratigraphic core log to outline the subsurface framework. The stratigraphic framework mapped geotechnical heterogeneities within the upper 6.0 m, where a low-resistivity anomaly (≤1 log(Ω·m)) outlines a mechanically weakened, water-saturated cover deposit overlaying the basaltic lava. This characterization provides the physical baseline useful for interpreting the site response. In this framework, the ambient vibration recordings performed at the free-field sites exhibit a flat Horizontal-to-Vertical Spectral Ratio (HVSR) response within the 1.0–10.0 Hz range, whereas a localized stratigraphic peak emerges at higher frequencies near 15.0 Hz, particularly evident in the building’s courtyard. The building resonance frequency peaks, derived from the Horizontal-to-Horizontal Spectral Ratio (HHSR) analysis at 3.74 ± 0.09 Hz (NS) and 3.58 ± 0.22 Hz (EW), do not overlap with the site resonance frequencies, demonstrating a dynamic decoupling between the soil and the building within the low-to-medium frequency domain. Conversely, the secondary stratigraphic peak near 15.0 Hz overlaps with higher-order structural frequencies tracked in the HHSR datasets. Given the localized nature of this stratigraphic peak and the involvement of higher-order structural modes, this overlap suggests a limited, localized high-frequency amplification confined to specific architectural components, rather than a global site-structure hazard. Furthermore, torsional analysis reveals significant effects within the 3.8–4.0 Hz frequency band, targeting the North-East corner (peak value of 2.85 at station A4), indicating a localized dynamic anomaly due to structural heterogeneities. Overall, this multi-method approach proves highly effective for non-invasive structural diagnostics, establishing a rigorous physical reference that could be successfully integrated into future preventive conservation frameworks and routine monitoring protocols for ancient architectural heritage. Full article

Individuals with transtibial amputation have impaired postural control due to limited ankle function. Conventional energy-storing-and-return (ESAR) prosthetic feet mainly support sagittal-plane mechanics and provide limited frontal-plane adaptability. This pilot pre–post motion analysis study examined the effects of the Intersection Foot^® (IF), a torsion-adaptive ESAR prosthetic foot, on balance control in 10 male individuals with unilateral transtibial amputation. Three-dimensional motion analysis and force plate measurements were performed during five Berg Balance Scale-derived tasks. During sit-to-stand, IF reduced the mediolateral root mean square distance of center of pressure from 10.20 ± 3.59 to 8.29 ± 3.32 mm (p = 0.047) and the anteroposterior center of mass (CoM) range from 345.51 ± 31.72 to 326.45 ± 47.40 mm (p = 0.008). During tandem stance, IF increased mediolateral CoM range from 23.94 ± 18.77 to 55.99 ± 30.90 mm (p = 0.021), vertical CoM range from 4.14 ± 4.18 to 9.45 ± 7.72 mm (p = 0.038), and sound-side frontal-plane ankle ROM from 1.44 ± 1.20° to 2.48 ± 1.30° (p = 0.022). Overall, replacing the habitual feet with IF produced task-dependent biomechanical adaptations rather than uniform improvements in postural stability, suggesting reduced dynamic sway during sit-to-stand but increased whole-body and sound-limb compensatory motion during tandem stance. Full article

To enhance critical infrastructure protection against low-cost UAV impacts, this study proposes a novel ring lattice sandwich structure (RLSS) fabricated via an economical interlocking-assembly-brazing method. Its quasi-static compressive behavior is systematically investigated through experiments, numerical simulations, and theoretical analysis. Theoretical models for relative density and initial yield stress are validated against experiments, with errors of 7.1% and 6.6%, respectively. Quasi-static tests show that the one-layer RLSS exhibits a specific energy absorption (SEA) of 8.67 J/g, while the two-layer structure drops to 5.66 J/g due to inter-layer torsional instability. SHPB impact tests at strain rates of 750–1369 s⁻¹ demonstrate a pronounced strain-rate effect, with dynamic increase factors ranging from 1.14 to 1.43. Numerical simulations accurately reproduce the experimental deformation modes and reveal that multi-layer (2–5 layers) RLSSs reduce SEA by 46.9% compared with the one-layer simulated value of 9.43 J/g. Adding a 0.3-mm inner panel in simulations restores the crushing mode and raises the SEA of the two-layer structure to 7.19 J/g, surpassing the non-panel counterpart (6.03 J/g). Hybrid core configurations provide additional advantages: Mode I (ring–pyramid with inner panel) enhances total energy absorption with a limited ring-layer count, while Mode II (alternating layers) achieves minimal plateau stress fluctuation (PSF = 0.09). These findings confirm that the proposed RLSS, especially when optimized with thin inner panels or hybrid designs, offers great potential as protective cladding against impact and blast threats. Full article

Objective: We aimed to evaluate the association between preoperative ultrasound features, dynamic changes, and ovarian outcomes in neonatal ovarian torsion, and to compare ovarian survival across ultrasound subgroups. Methods: This retrospective study included 58 neonates with prenatally or postnatally diagnosed ovarian cysts who had surgically confirmed ovarian torsion and were treated at our institution between June 2015 and July 2025. Results: Of the 58 cases, 45 (77.6%) underwent oophorectomy and 13 (22.4%) underwent ovary-sparing surgery. Ovarian survival was achieved in 44.4% (4/9) of simple cysts compared with 0% (0/49) of complex cysts (RD +44.4%, 95% CI: +14.8% to +74.1%; p < 0.001). Among the 9 simple cysts, only 2 (22.2%) had preoperative sonographic signs of torsion; the other 7 underwent surgery due to size-related indications, of whom 4 (57.1%) had necrosis at surgery. In the 50 cases with serial follow-up, observation window, cyst size changes, morphological shifts, and age at surgery did not differ significantly between the oophorectomy and ovary-sparing surgery groups (all global p > 0.05). Conclusions: In neonatal ovarian cysts with torsion, the overall ovarian survival rate was low (6.9%, 4/58). However, a salvageable subgroup was identified: simple cysts had a 44.4% (4/9) survival rate, whereas complex cysts had 0% (0/49), indicating that ovarian salvage is rarely achievable in complex cysts. The conclusions are limited to surgically confirmed ovarian torsion cases and should not be generalized to other neonatal ovarian cysts. Full article

In directional coring drilling, toolface adjustment is performed during drilling interruption by rotating the drill string through the top drive. Because the bottom-hole toolface angle cannot be transmitted to the surface in real time, a dynamic prediction model is required to guide toolface control. Existing flexible drill string models, however, generally neglect the nonlinear wellbore friction caused by stick–slip motion, reducing prediction accuracy. To address this issue, a distributed-parameter torsional dynamic model is established and discretized into a multi-degree-of-freedom system. A friction-state-based prediction–correction iterative algorithm is proposed to resolve the strong coupling between wellbore friction and system dynamics. At each time step, the sticking or slipping state is identified from the predicted motion, and the wellbore friction torque is iteratively updated until the friction state and dynamic equilibrium simultaneously converge, enabling accurate prediction of the drill bit toolface angle. Simulation results show that the proposed model captures the key dynamic characteristics of toolface adjustment. Under typical operating conditions, the drill bit start-up delay is 3.53 s, the peak angular velocity reaches 1.73°/s, and the peak transmitted torque is 2.28 kN·m. After the top drive stops, the drill bit continues rotating because of inertia, resulting in a 2.12° toolface overshoot and an angular lag rate of 21.2%. In addition, the effects of weight on bit, top-drive speed, and equivalent damping on toolface adjustment are quantified, providing guidance for parameter optimization. The proposed method provides a theoretical basis for toolface prediction and control in intelligent directional coring drilling. Full article

Transcription-coupled nucleotide excision repair (TC-NER) removes transcription-blocking lesions from active genes, but how lesion-stalled RNA polymerase II (RNAPII) is converted into a repair-accessible substrate remains incompletely understood. Active chromatin is dynamic but not topology-free. RNAPII elongation generates torsional stress that is buffered by nucleosome dynamics, chromatin remodelers, topoisomerases, and gene-body organization. Upon lesion-induced RNAPII arrest, this buffering system may fail locally, creating a topologically and architecturally constrained repair substrate. Here, we integrate established mechanisms of CSB-dependent RNAPII remodeling and recently defined ubiquitin-dependent clearance pathways with a testable model in which local torsional stress and topoisomerase-mediated relaxation influence repair permissiveness. In this framework, CSB remodels and organizes lesion-stalled RNAPII complexes, whereas topoisomerase may contribute to relaxation of transcription-generated supercoiling, thereby promoting a repair-permissive chromatin state. Recent evidence further indicates that CRL4^CSA-dependent RNAPII ubiquitylation initiates a hierarchical clearance program in which TFIIH/XPD drives rapid RNAPII displacement and VCP/p97 provides a backup extraction pathway. Together, these findings support a model in which TC-NER is possibly licensed not only by repair-factor recruitment but also by coordinated remodeling of RNAPII architecture, chromatin topology, and polymerase fate. Full article

Soil–structure interaction (SSI) can affect the apparent dynamic properties of instrumented buildings, and its long-term variability may complicate structural health monitoring when SSI effects are not explicitly tracked. This study presents a long-term monitoring analysis of SSI effects for a 17-story reinforced concrete building founded on soft soil in Acapulco, Mexico, using earthquake records collected between 2001 and 2022. The simplified Luco decomposition model is combined with a recursive subspace identification method to independently estimate the frequencies associated with the soil–structure system, the fixed-base structure, foundation rocking, foundation translation, and torsional response. The estimated frequencies are assessed through comparisons with classical spectral analysis and subsequently used to evaluate the long-term evolution of the equivalent SSI stiffness against analytical and numerical models. The results reveal a gradual reduction in both the system and fixed-base structural frequencies throughout the monitoring period, accompanied by a corresponding decrease in the equivalent stiffness. The proposed methodology provides consistent component-by-component SSI estimates from seismic recordings and supports the long-term identification and interpretation of SSI-related dynamic properties in instrumented buildings founded on soft soils. Full article

Zoledronic compounds are widely used as antiresorptive and antitumor agents to prevent bone loss and treat multiple myeloma; however, their pharmacokinetic limitations motivate the search for alternative delivery systems capable of improving their controlled release and bioavailability. In this work, we investigate the stability, structural behavior, and adsorption properties of zoledronic acid (ZOL) and its Ca²⁺ and Zn²⁺ salts confined within the interlayer space of the smectite clay mineral montmorillonite by combining empirical force field (FF), density functional theory (DFT), and molecular dynamics (MD) simulations. The main objective of this study is to evaluate the suitability of montmorillonite as a potential drug delivery system (DDS). Specifically, crystal polymorph structures of zoledronic acid [1-(2-hydroxy-2-phosphonate-2-phosphonoethyl)-1H-imidazol-3-ium)] (ZOL) and its Ca²⁺ and Zn²⁺ salts were analyzed. Our calculated crystal structures obtained by both methods (FF and DFT) agree well with the known experimental data. Furthermore, the intercalation of ZOL into the confined interlayer space of montmorillonite is energetically favorable. Several interlayer cations (Na⁺, Ca²⁺, and Zn²⁺) were also evaluated. MD simulations showed that ZOL adopts stable confined configurations within the interlayer space of montmorillonite, exhibiting small torsions of the imidazole group. Additionally, the desorption of ZOL in a modelized acidic medium is energetically favorable. Our calculations predict that this clay mineral holds strong potential for the controlled delivery of zoledronic compounds. Full article

Carbon fiber reinforced plastic (CFRP) composites have been widely adopted in the aerospace industry due to their excellent mechanical and physical properties. However, their anisotropy and weak interlaminar bonding make them prone to defects such as delamination and fiber pull-out during conventional drilling (CD). Longitudinal-torsional coupled ultrasonic vibration-assisted drilling (LTC-UAD) integrates axial and circumferential vibrations to suppress hole defects and is considered a promising machining method for improving the quality of holes drilled in CFRP. Based on kinematic analysis, a model for the working rake angle of the main cutting edge is established to obtain the variation law of the maximum working rake angle along the cutting edge. Compared with CD and longitudinal ultrasonic vibration-assisted drilling (L-UAD), LTC-UAD significantly increases and homogenizes the maximum working rake angle of the main cutting edge, which helps optimize its cutting performance. A three-dimensional finite element model of CFRP is constructed to analyze the dynamic fiber removal process under typical fiber orientations. Finally, drilling experiments are performed to observe the hole wall micro-morphology at various fiber angles. The simulation results indicate that ultrasonic vibration causes periodic changes in the fiber cutting angle, subjecting the fibers to a directional shear state and making them more prone to shear fracture. Two-dimensional ultrasonic vibration cutting enhances the directional shear effect, promotes fiber fracture, accelerates chip removal, and improves the quality of the machined surface. Experimental observations confirm LTC-UAD alleviates fiber crushing, bare fibers, and surface cavities with uniform resin coverage. Furthermore, ultrasonic vibration suppresses thrust force. L-UAD and LTC-UAD yield 10.6% and 17.1% reductions via periodic cutting depth variation and facilitated carbon fiber shear fracture. Full article

This paper presents the research, development, and functional validation of an original rear suspension system designed for hybrid reverse trike vehicles (two guided wheels on the front axle and a twin-tire-driven assembly at the rear). Conventional configurations featuring a single rear wheel exhibit severe limitations regarding lateral stability under critical dynamic regimes and induce roll-induced torsional loading in flexible chain drives. The proposed solution utilizes a twin-tire rear assembly integrated into an articulated suspension mechanism with two degrees of freedom (2 DoF), which reconfigures the geometric stability polygon from a triangle into an isosceles trapezoid. A mathematical model based on tire dynamics and tire slip phenomena demonstrates that introducing a controlled roll stiffness on the rear axle stabilizes the slip angles, ensuring a neutral and predictable steering behavior. Structural validation via finite element analysis (FEA) performed in SOLIDWORKS Simulation on the entire assembly under a conservative combined load scenario (2400 N vertical force shared by the two wheel bearings, 2400 N lateral force, and 1200 N tractive force) indicated a minimum factor of safety of 1.26 on S275N structural steel, confirmed by an eleven-run mesh independence study. Finally, the system’s functionality was experimentally confirmed through the manufacturing and road testing of a full-scale (1:1) demonstrator vehicle powered by an 1129 cc Boxer engine, highlighting a measurable increase in rollover resistance and trouble-free operation of the two-stage chain drive throughout the test program. A numerical evaluation shows that for rear-biased vehicles of the category the proposed axle raises the rollover-related lateral acceleration threshold by up to 54% and replaces the strongly oversteering balance of the single-wheel layout with a near-neutral, tunable one. Full article