Conventional strategies for enhancing the mechanical robustness of thermoplastic polyurethane elastomers (TPUs) rely on hard-segment engineering, such as introducing dynamic covalent/noncovalent bonds or optimizing chain extenders, yet overlook the critical role of soft segments in governing microphase separation. Here, we present a soft-segment-regulated design that leverages crystallizable polyols to synergize hierarchical hydrogen bonding, tunable microphase separation, and strain-induced crystallization (SIC), achieving excellent mechanical performance. Among them, PU-PTMEG exhibits exceptional mechanical properties, including a tensile strength of 75.6 MPa, a toughness of 337.4 MJ m-3, and a fracture energy of 131.6 kJ mol-1-values that surpass those of many metals and alloys. Furthermore, its true fracture stress reaches 1.03 GPa, comparable to that of spider silk, while its toughness is approximately 2.3 times higher, demonstrating a remarkable combination of strength and toughness. The dynamic yet dense hydrogen bond network, strategically balanced in both strength and reversibility, enables efficient energy dissipation during deformation, while the SIC activated by aligned soft segments facilitates elastomer self-reinforcement. Finally, by combining the antibacterial properties endowed by intrinsic acylhydrazine groups (bacterial survival rate <20%) and the introduction of rigid polyurethane foam as an acoustic impedance modifier, high-contrast ultrasound imaging of TPU wires has been successfully achieved.

Study on bonding quality of cement-casing interfacial transition zone based on acoustic impedance testing: Influence of microstructural characteristics

This work aims the processing of multifunctional thermoset composites, consisting of carbon fibers/epoxy resin prepreg, and polybutadiene (BR) mats produced via electrospinning process aiming to provide a composite material with high tenacity. Initially, polybutadiene mats were produced by electrospinning. These mats and prepregs materials were hot compressed at eight different configurations to produce the composites. The quality of the manufactured composites was evaluated by acid digestion, dynamic mechanical analysis (DMA), acoustic ultrasound inspection, impulse excitation, and impact resistance tests. The composites with six layers of electrospun BR showed higher storage modulus value (DMA test), and no significant change was observed in its energy absorption values of impact resistance test. However, it was possible to verify that the presence of the BR mats in the composites hindered the propagation of damage in the material.

This study presents the results of a numerical investigation into the influence of geometric parameters, particularly the fillet radius, on the dynamic characteristics of an ultrasonic stepped velocity transformer. Such transformers are employed in high-frequency electromechanical systems to match the acoustic impedances between the transducer and the load, as well as to increase the amplitude of mechanical vibrations. Modeling was carried out using the finite element method (FEM), which enables consideration of the spatial distribution of stresses and strains within the transformer volume. The effects of the step diameter and acoustic length on the resonance frequency and amplification coefficient were analyzed. It has been established that an increase in the step diameter leads to a decrease in the resonance frequency, whereas an increase in the fillet radius results in its rise. Quantitative relationships between the fillet radius, transformation coefficient, and resonance frequency were obtained, allowing for approximate determination of optimal design parameters. It was shown that enlarging the fillet radius reduces stress concentration in the transition zone between steps, thereby enhancing the fatigue strength of the structure. An empirical relationship was proposed for preliminary estimation of the fillet radius to ensure agreement between the actual and the calculated resonance frequencies. The results obtained can be applied in the design and optimization of ultrasonic amplification systems and transducers used in ultrasonic welding, material processing, and surface modification technologies.

ABSTRACT Engineers face a major challenge when understanding how internal molecular interactions, such as shapes and aggregation kinetics, affect the fluid’s thermal physical properties. As a result, figuring out the ideal particle’s thermal effect at the nanoscale depends critically on the aggregation kinematics of nanoparticles. Thus, this investigation aims to study the characteristics of the aggregated nanoparticles and how they influence the slip flow of a power-law nanofluid towards a thin needle. Further, the effects of the heat source/sink are taken into account. After converting the governing equations to a nondimensional version with appropriate transformation, the BVP4c approach is implemented to solve it. The outcomes reveal that the velocity profile diminished for higher values of Ag -volume fraction, power-law index, and thermal slip parameter. Velocity and thermal slip effects reduced the temperature distribution. Additionally, regression analysis is performed to establish a deeper understanding of engineering quantities. The heat transmission rate in the aggregating nanoparticle improved relative to the non-aggregating nanoparticle as the Ag volume fraction and velocity slip parameters were enhanced. Aggregated nanoparticles maximize cooling efficiency, enhancing electronic devices’ reliability and lifespan and improving performance.

Reducing the consumption of energy-intensive cement and promoting the resource utilization of industrial waste are two critical challenges that should be urgently addressed to achieve the goals of carbon neutrality and green sustainable development in the building materials field. Among these, the massive stockpiling of industrial waste such as fly ash and silica fume poses serious threats to the environment and human health, making their efficient utilization an urgent need to alleviate environmental pressure. This study employs the ice-template method to incorporate fly ash and silica fume as functional components into a cement-based system, fabricating a novel composite material. This material features a layered porous structure, which not only reduces cement usage but also results in a lighter weight. The introduction of the ice-templating method successfully constructed an anisotropic lamellar structure, leading to significant enhancements in flexural strength and toughness-by approximately 26.6% and 30%, respectively, vertical to the lamellae compared to conventional dense cement. Meanwhile, the hybrid blend of silica fume and fly ash effectively improved the deformability of the material, as evidenced by a notable increase in compressive failure strain. These excellent behaviors of mechanical properties are attributed to the formation of a multi-scale microstructure characterized by "macroscopically continuous and microscopically dense" features. Moreover, this specific microstructure offers greater advantages in sound absorption performance. The acoustic impedance tube tests demonstrate that the noise reduction coefficient of the novel cement-based material incorporating fly ash and silica fume is improved by 82%, holding promising applications in noise reduction for the construction and transportation fields. This research provides a feasible pathway for the high-value application of industrial solid waste in low-carbon materials.

Linear electromagnetic wave scattering systems can be characterized by an impedance matrix that relates the voltages and currents at the ports of the system. When the system size becomes greater than the wavelength of the fields involved, the impedance matrix becomes a complicated function of the details of the system, in which case a statistical model, such as the random coupling model, becomes useful. The statistics of the elements of the random coupling model impedance matrix depend on the excitation frequency, the spectral density of the modes of the enclosed system volume, the average loss factor (Q-1) of the system, and the properties of the coupling ports as given by their radiation impedances. In this paper, properties of the elements of impedance matrices are explored numerically and experimentally. These include the two-point frequency correlation functions for the complex impedance of elements and the expected difference in frequencies between which impedance values are approximately repeated. Universal scaling arguments are then given for these quantities; hence, these results are generic for all sufficiently complicated scattering systems, including acoustic and optical systems. The experimental data presented in this paper come from microwave graphs, billiards, and three-dimensional cavities with embedded tunable perturbers such as metasurfaces. The data is found to be in generally good agreement with the predictions for the two-point frequency correlations and the frequency interval for successive repetitions of impedance matrix element values.

Otitis media with effusion (OME) is a common middle ear disease characterized by fluid accumulation without acute infection, leading to conductive hearing loss. Conventional diagnostic tools, such as tympanometry and otoscopy, have limited sensitivity and rely on expert interpretation. This study investigates vibro-acoustic radiation (VAR) as a novel, non-invasive, and objective method for OME detection. VAR signals were obtained from 36 OME patients (43 ears) and 15 normal ears using bone-conduction excitation and stereo microphones, and the frequency response functions were analyzed. OME increases the mechanical loading of the tympanic membrane and ossicular chain, thereby modifying sound transmission across the middle ear. Using a simplified theoretical model, we estimated acoustic parameters of the ear canal, eardrum, and middle ear, including specific acoustic impedance and resonance frequency ranges, to interpret changes in VAR. VAR analysis revealed significantly reduced signal amplitude in the 8–10 kHz range in OME ears compared with normal ears (p &lt; 0.05). A classification algorithm based on these features achieved 86.7% accuracy, 85.0% sensitivity, and 80.0% specificity, with an area under the ROC curve of 0.986. These findings suggest that VAR has strong potential as a non-invasive diagnostic tool for OME, warranting validation in larger clinical studies.

The paper presents an analysis of the dynamic properties of multilayer protective structures formed by the additive method (3D printing), with an emphasis on the mechanics of elastic waves. The evolution from quasi-static characteristics (2010s) to dynamic ones (2020s), including Koch-type fractal structures for controlling wave dispersion, is considered. Additive manufacturing provides a controlled microstructure with the integration of reinforcing elements (such as fiber), minimizing waste and implementing exclusion zones according to the Bloch-Floquet theory. The physics of elastic waves is detailed: classification; propagation velocities; their interaction with the boundaries of layers of different acoustic impedances. Energy absorption is modeled by a hysteresis loop, with sources of dissipation: hysteresis, structural and aerohydrodynamic. The coefficient of energy absorption is increased by fiber reinforcement, with the phases of destruction: pre-fracture, fractured and post-fracture. The aim is to simulate wave dynamics in 3D structures, to identify the advantages and disadvantages of enclosing structures constructed in an additive way compared to traditional monolithic products.

Objective. To analyze quantitative parameters of pathological venous reflux in patients with chronic diseases of the veins of the lower extremities and to evaluate their diagnostic significance. Materials and methods. A prospective single-center study included 73 patients with chronic diseases of the veins of the lower extremities (clinical classes C2–C6). The average age of patients was (48.6 ± 6.4) years, the average body mass index was (26.1 ± 1.2) kg/m2. Distal manual compression and the Valsalva maneuver were used to provoke venous reflux. In the projection of the saphenofemoral junction of the great saphenous vein, its cross-sectional area, duration, volume, and time-averaged reflux velocity were measured. Results. When performing distal manual compression and the Valsalva maneuver, the cross-sectional area of the great saphenous vein was (0.71 ± 0.35) and (0.76 ± 0.39) cm² 2, respectively, and the duration of the reflex was (2.9 ± 1.78) and (3.8 ± 1.64) s, the volume of reflux was (226.17 ± 218.9) and (269.48 ± 288) ml/min, respectively, and the time-averaged reflux velocity was (4.68 ± 3) and (5.25 ± 3.7) cm/s, respectively. A strong positive correlation was found between the area of the large subcutaneous vein in its transverse section and the volume of reflux during both distal manual compression (r=0.85) and the Valsalva maneuver (r=0.75), as well as between the volume and time-averaged reflux velocity. Higher values of the studied parameters were associated with a higher clinical class of chronic venous disease. Conclusions. The volume and time-averaged velocity of reflux can serve as effective criteria for assessing the severity of chronic venous disease.

Patients with postural orthostatic tachycardia syndrome (POTS) experience disabling symptoms such as brain fog related to reduced cerebral perfusion. The objective of this study is to determine the mediating role of carbon dioxide in the relationship between stroke volume and cerebral blood flow. A total of 15 female patients with POTS underwent head-up tilt testing under two conditions: with lower-body compression (higher stroke volume) and without (lower stroke volume). We analyzed cerebral blood flow velocity, respiratory, and cardiovascular responses using linear mixed-effects and mediation models to examine stroke volume-cerebral blood flow interactions. Granger causality and wavelet coherence assessed cerebral autoregulation. Lower-body compression attenuated the reduction in stroke volume (-34ml versus -23ml; p < 0.01), end-tidal CO2 (-6.4mmHg versus -3.2mmHg; p < 0.01), and mean middle cerebral artery blood flow velocity (-11.2cm/s versus -4.2cm/s; p < 0.01) during tilt. Mediation analysis revealed that carbon dioxide completely mediated the relationship between stroke volume and middle cerebral artery blood flow velocity, with a significant indirect effect (0.18cm/s/ml, 95% confidence interval (CI) 0.058-0.33) and a nonsignificant direct effect (0.04cm/s/ml, p = 0.5). Compression attenuated the association between stroke volume and carbon dioxide (-0.07mmHg/ml; 95% CI -0.12 to -0.010; p = 0.02), as shown by the linear mixed-effect model, and reduced the directional influence of blood pressure on cerebral blood flow (ΔGranger causality: 0.12 (0.05-0.18) versus 0.05 (0.02-0.08); p < 0.01). Reduction in stroke volume leads to reduced cerebral perfusion in POTS, an effect likely mediated by decreased carbon dioxide.

Summary This review article outlines the current clinical applications of wideband tympanometry (WBT), a modern and advanced method for assessing the mechanics of the middle ear transmission system. Compared to conventional tympanometry, WBT enables analysis over a broader frequency range. The article places WBT within the historical context of immittance testing development, explains its underlying principles, and highlights its advantages over conventional methods. The main section focuses on clinical applications, primarily in the diagnosis of middle ear diseases such as secretory otitis media, otosclerosis, ossicular chain discontinuity, tympanic membrane perforation, and chronic otitis media. The article further explores the use of WBT in evaluating inner ear pathologies, such as endolymphatic hydrops and third window syndrome, implementation of WBT in newborn hearing screening, and summarizes potential new areas of application, including intracranial pressure monitoring and early postoperative follow-up after middle ear surgery. The discussion also addresses the limitations of the method, the need for standardized interpretation of results, and the potential offered by future integration of artificial intelligence in analyzing complex WBT data. Key words acoustic impedance tests – tympanometry – middle ear diseases – wideband tympanometry

Embedding nanoparticles into host materials offers a powerful strategy for tailoring acoustic properties, with significant implications for non-destructive testing and acoustic engineering. Cryo-ultrasonics - a technique that employs ice as a couplant - has emerged as a promising approach for inspecting components with complex geometries. However, its performance is hindered when testing metallic parts due to the pronounced acoustic impedance mismatch between ice and metal. To address this challenge, we propose enhancing the ice matrix with nanoparticles composed of the same material as the target metal, thereby improving acoustic coupling and signal transmission. This study focuses on the role of solid alumina (Al₂O₃) nanoparticles in modifying the ultrasonic properties of ice composites, with particular attention to the effect of a nanometric interfacial water layer between the ice matrix and particles. We investigate this behavior across a temperature range from −5 °C to −60 °C using both 2D and 3D numerical homogenization simulations, and validate our results with experimental measurements. Our findings reveal that including the water layer is critical -especially at lower temperatures - for accurately predicting compressional wave velocities, significantly outperforming classical analytical models. Furthermore, we demonstrate that a 2D simulation framework provides excellent agreement with full 3D models, offering considerable computational efficiency without sacrificing accuracy.

With the large-scale construction and long-term operation of underground reservoirs in coal mines, the problem of surrounding rock stability under long-term water immersion has become increasingly prominent. Therefore, clarifying the dynamic response of rocks under long-term immersion and impact loads is of great theoretical significance for ensuring the safe operation of coal mine reservoirs throughout their entire life cycle. In this study, sandstone samples were immersed in water for 0, 3, 30, 90 and 180 days respectively. The microstructure characterization and dynamic tests were carried out by using nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), computed tomography (CT), and an improved separated Hopkinson compression bar (SHPB) system. The results show that: (1) The combined results of SEM, NMR and CT tests indicate long-term impregnation reduces the proportion of micropores and increases the proportion of mesopores and macropores. The total dissolved solids (TDS) concentration in the impregnating solution increases with time, and the pH value of the solution first rises and then decreases with the extension of the immersion time. (2) The faster the impact velocity, the greater the frequency and amplitude of the stress wave generated. The water saturation gradually increases with immersion, weakening the discontinuity of acoustic impedance and reducing the reflection coefficient at the interface. (3) The increase in impact velocity intensifies fragmentation and promotes the development of complex fracture networks. With the extension of immersion time, the expansion of clay minerals such as montmorillonite will generate expansion stress, thereby creating micro-cracks, which leads to a higher fractal dimension of the crack network and eventually stabilizes over time. (4) Under the action of impact loads, the proportion of intergranular fractures increases with the extension of immersion time. However, at high impact speeds, the relative strength contrast between the cementing material and quartz particles leads to an increase in transgranular fracture. Overall, this study provides guidance for the safe design and operation of underground reservoirs in coal mines.

Noise is a significant environmental factor that must be eliminated by appropriate means. This study investigates the acoustic insulation properties of 3D-printed porous materials with an octet-truss lattice structure, fabricated using fused filament fabrication (FFF) technology. The sound insulation performance of the tested materials was evaluated based on the frequency dependent sound absorption coefficient, which was experimentally determined using an acoustic impedance tube. In this work, several parameters affecting the sound absorption properties of the investigated lattice material structures were systematically analysed, including volume ratio, sample thickness, excitation frequency, and the presence of air gaps. Based on the findings, specific recommendations are proposed to enhance the sound absorption characteristics of the octet-truss lattice structures and thereby reduce unwanted noise.

Abstract Waterborne acoustic metamaterials have emerged as promising platforms for manipulating underwater sound propagation within the subwavelength regime. Despite their critical role in underwater stealth applications, conventional designs face dual limitations: inefficient low‐frequency broadband absorption and poor mechanical load‐bearing capacity due to their inherently soft architectures. The longstanding acoustic‐mechanical trade‐off underscores an urgent need for co‐design strategies that synergistically reconcile these conflicting requirements. Herein, an ultrathin strut‐alterable trussed composite waterborne metamaterial is proposed as an acoustic‐mechanical coupling design paradigm. By strategically tuning the truss geometry via an artificial neural network (ANN), this design enables precise acoustic impedance matching through tailored local resonances while simultaneously constructing a stress‐redistribution framework for mechanical reinforcement. Experimental results demonstrate the outstanding broadband sound absorption performance (average sound absorption coefficient &gt; 0.88) spanning 0.8–10 kHz with a subwavelength thickness of ∼λ/ 33.8 at 1.2 kHz. Remarkably, the waterborne metamaterial structure achieves a maximum bearing stress of 18.48 MPa, representing an order of magnitude enhancement compared to non‐trussed counterparts (0.035 MPa) at the same strain. This work opens a new multi‐functional design path and provides more possibilities for the applications of underwater vehicles.

Nano Silica Fume (NSF) is characterized by its ultrafine particle size and high pozzolanic reactivity, and it has shown great potential in enhancing the structural and functional properties of cement-based materials. In this work, NSF was incorporated into Barium-Zirconate-Titanate (BZT) cement composites to assess its influence on the dielectric, piezoelectric, and mechanical behavior of the system. The microstructural examinations revealed that the NSF addition refined the internal morphology, improved the BZT particle dispersion, and stimulated the formation of additional Calcium Silicate Hydrate (C-S-H), resulting in a denser and more uniform matrix. The dielectric measurements indicated a notable increase in relative permittivity and a reduction in dielectric loss, primarily attributed to the improved BZT interconnectivity and interfacial polarization. The incorporation of NSF also enhanced the matrix-filler bonding and electromechanical coupling, leading to higher piezoelectric coefficients and better acoustic impedance. It additionally caused a significant improvement in the compressive strength of the cement mortar compared to the unmodified BZT-cement composite. The findings indicate that NSF functions simultaneously as a microstructure modifier and a performance enhancer, thus broadening the application of BZT-cement composites for multifunctional sensing and structural health monitoring purposes.

To address the issue of sound absorption valleys in open-cell aluminum foam and enhance mid-to-high frequency (800–6300 Hz) performance, we developed a novel pore-penetrating 316L stainless steel fiber–aluminum foam (PPFCAF) composite using an infiltration method. The formation mechanism of the pore-penetrating fibers, the resultant pore-structure, and the accompanying sound absorption properties were investigated systematically. The PPFCAF was fabricated using 316L stainless steel fiber–NaCl composites created by an evaporation crystallization process, which ensured the full embedding of fibers within the pore-forming agent, resulting in a three-dimensional fiber-pore interpenetrating network after infiltration and desalination. Experimental results demonstrate that the PPFCAF with a porosity of 82.8% and a main pore size of 0.5 mm achieves a sound absorption valley value of 0.861. An average sound absorption coefficient is 0.880 in the target frequency range, representing significant improvements of 9.8% and 9.9%, respectively, higher than that of the conventional infiltration aluminum foam (CIAF). Acoustic impedance reveal that the incorporated fibers improve the impedance matching between the composite material and air, thereby reducing sound reflection. Finite element simulations further elucidate the underlying mechanisms: the pore-penetrating fibers influence the paths followed by air particles and the internal surface area, thereby increasing the interaction between sound waves and the solid framework. A reduction in the main pore size intensifies the interaction between sound waves and pore walls, resulting in a lower overall reflection coefficient and a decreased reflected sound pressure amplitude (0.502 Pa). In terms of energy dissipation, the combined effects of the fibers and refinement increase the specific surface area, thereby strengthening viscous effects (instantaneous sound velocity up to 46.1 m/s) and thermal effects (temperature field increases to 0.735 K). This synergy leads to a notable rise in the total plane wave power dissipation density, reaching 0.0609 W/m3. Our work provides an effective strategy for designing high-performance composite metal foams for noise control applications.

Purpose In this paper, a theoretical analysis model for vibration control of stiffened cantilever plates is established based on Kirchhoff plate theory and Euler–Bernoulli beam theory to reveal the physical mechanism of vibration control from the perspective of resonance modes. Design/methodology/approach The vibration response of a stiffened cantilever plate under the action of external concentrated forces and multi-stage control forces is solved based on the finite integral transform method. A detailed derivation is then conducted to elucidate the fundamental process of controlling the plate vibration using the cancellation volume velocity method. The vibration control performance of the cantilever plates is investigated, and the influence of the stiffener, the number of control sources and the applied position on the vibration control are analyzed. Findings Satisfactory damping effect can be obtained after vibration control of cantilever plate structures. For the control system of a single force source, the influence of stiffener on vibration control of cantilever plates depends on the role played by the stiffener in the modal vibration. For the control system of multi-stage force source, the failure of a single control force can be avoided effectively because the force sources are distributed on the plate surface. Originality/value The theoretical model for vibration control of stiffened cantilever plates is solved using the finite integral transform and cancellation volume velocity method and exploring the influence of the stiffener and various control parameters on the damping effect. It provides new insights into the physical mechanisms of vibration control and offers practical strategies to enhance the performance of cantilever plate structures.

The design and analysis of a small hexagonal ring microstrip antenna optimized at 5.5 GHz are presented in this work. The FR4 substrate, which has a dielectric constant of 4.3 and a thickness of 1.6 mm, is used to fabricate the antenna because it is inexpensive and compatible with printed circuit board technology. By extending the effective current path and allowing for multiple resonant modes, the hexagonal ring geometry improves radiation performance and impedance bandwidth when compared to traditional rectangular patches. Using CST Microwave Studio, Characteristic Mode Analysis (CMA) is used to analyze the antenna's modal behavior. According to the CMA results, higher-order modes aid in stability, but the dominant resonant mode around 5.5 GHz largely controls the radiation mechanism. With an impedance bandwidth of 126 MHz (5.392–5.518 GHz), the simulated response exhibits a resonance of –20 dB at 5.5 GHz. The antenna produces strong current distribution along the hexagonal edges, broadside radiation, and a steady gain of 6.11 dBi. The design is appropriate for WLAN and Wi-Fi 5 (IEEE 802.11ac) applications because of these features. The hexagonal ring structure is an efficient technique for increasing bandwidth and performance in wireless systems, as demonstrated by the combination of CMA and full-wave simulations.