Search Results (382)

Self-compacting concrete (SCC) is widely adopted in complex structural engineering due to its excellent flowability and filling capacity. However, in harsh corrosive environments, its complex internal pore structure can easily serve as a preferential pathway for the transport of aggressive media, leading to durability deterioration. This study systematically investigates the effects of chemical attack inhibitor (CAI) on the workability, mechanical properties, sulfate attack resistance, and chloride ion penetration resistance of SCC. The micro-mechanisms governing pore structure evolution are elucidated using low-field nuclear magnetic resonance (LF-NMR) and X-ray computed tomography (X-CT). At a CAI dosage of 2%, the fresh SCC exhibits a slump of 260 mm and slump flow of 720 mm, indicating excellent filling and gap-passing abilities. Meanwhile, the compressive strengths at 3 d, 7 d, and 28 d remain at a high level. After 120 sulfate wet-dry cycles, the strength loss rate is only 8.4%, with an erosion resistance coefficient exceeding 90%. In addition, the resistance to chloride ion penetration is significantly improved, with an electric flux of only 1331 C, which is considerably lower than that of the control group (1637 C). At the optimal dosage of CAI, the concrete exhibits a dense and uniform internal structure devoid of macroscopic defects or cracks, with minimized porosity, thus synergistically enhancing the resistance to sulfate attack and chloride attack. On the contrary, further increasing the CAI dosage markedly intensifies the inhibitory effect of organic components on cement hydration, leading to increased early-age defects and enhanced pore connectivity. Thus, an appropriate amount of CAI can effectively improve the overall performance of SCC, providing a solid experimental basis and theoretical support for its engineering application in harsh corrosive environments. Full article

The most recent research has demonstrated that oscillatory nano-structures found on the lumenal walls of deep cerebral veins likely contribute significantly to the regulation of the function of deep cerebral veins. The oscillatory nano-structures consist of very small, intricately organized “nanoflaps,” each consisting of a hinge element with an attached lipid bilayer architecture. These nanoflaps have distinct mechanical properties, are in close proximity to mechanically sensitive protein assemblies, and therefore it is hypothesized that the nanoflaps generate rhythmic oscillations that control the distribution of both pressure and fluid flow through the veins and also regulate the metabolic condition of the surrounding tissue. In addition, the behavior of the nanoflaps indicate that there exists a hitherto unappreciated level of venous biomechanics at the nanometer scale that regulates the hydraulic stability of the veins and may also contribute to the structural integrity of the surrounding tissues. The purpose of this review is to provide a theoretical framework for understanding the recent discoveries of the structure, oscillation and hydrodynamic effects of nanoflaps, including resonance drift, waveform irregularity, and multi-scale biomechanical interactions. Additionally, this review will present the idea that disruption of the normal oscillatory processes that occur in the nanoflaps may lead to the development of abnormal micro-environments in the early stages of neurodegenerative diseases, abnormalities of compliance, dysautonomic states, traumatic injury and micro-circulatory stress. Finally, this review will describe several pharmacological strategies that may be used to stabilize the oscillations generated by the nanometer-scale oscillatory nano-structure by modifying the torque applied to the hinge, the viscoelasticity of the membrane and the feedback pathways for mechanotransduction. Full article

Thermally induced frequency shift (FS) and energy dissipation are key factors limiting the quality factor (Q-factor) of resonators. This study combines nonlocal elasticity theory (NET) with the nonlocal dual-phase-lag (NDPL) heat-conduction model to establish a theoretical framework for evaluating thermoelastic damping (TED) in micro/nano cylindrical shells with size-dependent effects. The equation of motion of the cylindrical shell is simplified using the Donnell–Mushtari–Vlasov (DMV) approximation. The resonant frequency of the cylindrical shell with size-dependent effects is obtained by combining the compatibility equation with the equation of motion and applying the Galerkin method. Additionally, an analytical solution for the TED of cylindrical shells considering size effect under classical boundary conditions is derived using the complex frequency method. The proposed formulation is validated by comparing its predictions with available numerical results. Numerical results indicate that size effects have a significant impact on the TED of cylindrical shells, particularly as mechanical nonlocal effects increase TED, thereby reducing the Q factor of micro/nano cylindrical shells. Moreover, the impact of size effects on the FS and frequency attenuation (FA) is examined. This study lays crucial theoretical groundwork for the design of resonators utilizing micro/nano cylindrical shell materials. Full article

High-pressure hydrogen exposure may induce transport and diffusion–relaxation–controlled changes in elastomeric sealing materials that differ from conventional fluid aging. Hydrogen uptake through solution–diffusion processes can lead to swelling, redistribution of molecular mobility, viscoelastic evolution, and, under certain conditions, cavitation or microvoid formation during decompression, which may affect long-term sealing performance. This review compiles experimental results for commonly used elastomers, including Nitrile Butadiene Rubber (NBR), hydrogenated nitrile butadiene rubber (HNBR), Fluoroelastomer (FKM), Ethylene Propylene Diene Monomer (EPDM), and silicone, and summarizes reported ranges of hydrogen diffusivity, solubility, and permeability under high-pressure conditions. These transport characteristics are compared with mechanical and microstructural observations obtained from Dynamic Mechanical Analysis (DMA), Nuclear Magnetic Resonance (NMR), decompression testing, and micro-computed tomography (µXCT) imaging. Available evidence suggests that hydrogen-induced changes are predominantly governed by physical processes, including swelling, plasticization-like mobility changes, and constraint redistribution, while extensive chemical degradation of the polymer backbone is generally limited under clean hydrogen conditions. Materials with similar conventional mechanical properties may, therefore, exhibit different hydrogen uptake, viscoelastic response, and resistance to decompression damage. Conventional single-point mechanical tests, such as tensile measurements, may not fully capture the time-dependent viscoelastic evolution relevant to sealing performance. This work proposes a multiscale characterization framework integrating transport, viscoelastic, molecular, and microstructural analysis for more reliable evaluation of elastomers in hydrogen service, supporting improved qualification strategies for high-pressure hydrogen systems. Full article

This review comprehensively examines magnetic nanomaterials, ferrofluids, and their integration into ferrogel systems, systematically exploring their structural characteristics, dynamic behaviors, preparation techniques, and applications across medical and engineering fields. Structural characterization reveals that particle size and dispersibility directly influence functional efficiency in fluid and gel matrices, such as SAR (specific absorption rate) values in hyperthermia applications. For ferrofluids and magnetic gels, macroscopic behaviors and microscopic mechanisms are governed by key parameters like the magnetic Bond number. Preparation encompasses green synthesis, chemical reagent synthesis, and the cross-linking of these nanoparticles into hydrogel networks. Applications span diverse areas: in medicine, these include targeted hyperthermia, pH-responsive magnetic gel drug delivery, and MRI (magnetic resonance imaging); in engineering, applications range from efficient extraction and triboelectric power generation to magnetically regulated heat transfer and soft gel robotics. The paper also discusses current challenges, including material stability and unclear micro–macro correlations in complex fluid–gel systems, outlining future research directions for multifunctional magnetic materials. Full article

Objectives: Concentrated pills, as a modernization and upgrade of traditional pills, have achieved significant advancements in dosage form. However, their extended disintegration and dispersion times have become a major limitation to their therapeutic efficacy. Therefore, an in-depth study and explanation of the dissolution mechanism of concentrated pills, along with the development of processing technology to control dissolution time, has emerged as a critical bottleneck in improving the quality of concentrated pills. Methods: In this study, the Liuwei Dihuang (LWDH) concentrated pill, derived from the classical Liuwei Dihuang pill, was selected as a representative model. Two drying methods—hot-air drying and hot air–microwave combined drying—were comparatively investigated to evaluate their effects on dissolution time. The dissolution behavior was elucidated by analyzing water migration during the dissolution process, as well as the textural properties and internal structural characteristics of the pills using Low-Field Nuclear Magnetic Resonance (LF-NMR), Micro-Computed Tomography (Micro-CT), texture analysis, and other modern techniques. Results: The results indicated that: (i) The rate of water absorption during the dissolution process of the LWDH pill was influenced by the number and size of the internal pores. (ii) Hot air–microwave combined drying results in more pores and faster dissolution. (iii) High-Performance Liquid Chromatography (HPLC) fingerprints showed no significant differences in the active ingredients between the samples. Conclusions: The drying method significantly affected the internal structure of the pills, suggesting that controlling the drying process could address the prolonged dissolution time of concentrated pills. Full article

This paper provides a comprehensive overview of the progress in fiber-optic gyroscope technology, covering 260 key studies of the last ten years. A critical comparative analysis of fiber-optic gyroscope with alternative inertial sensors (Micro-Electro-Mechanical Systems, Hemispherical Resonator Gyroscope, Ring Laser Gyroscope) has been carried out. Confirming the unique advantages of fiber-optic gyroscope for autonomous navigation. Fundamental limitations of accuracy are considered in detail: temperature drifts, polarization noise, and Rayleigh backscattering. Modern hardware methods for suppressing these errors, including the use of photonic crystal and hollow fibers (Air-Core/Hollow-Core), are also considered in this work. The central place in the review is occupied by the analysis of the technological paradigm shift from bulky discrete circuits to hybrid integrated photonics (Indium Phosphide, Silicon Nitride, Lithium Niobate) and hybrid architectures to reduce weight and size characteristics. The role of artificial intelligence (Deep Learning, Long Short-Term Memory) methods in nonlinear drift compensation and calibration is discussed. The usage of the Brillouin effect and optomechanics promising areas are outlined, necessary to create a new generation of navigation systems operating in the absence of Global Navigation Satellite Systems signals. Full article

Acoustic emission (AE) monitoring in metal additive manufacturing (AM) requires compact sensors capable of high-frequency operation, broad bandwidth, and high sensitivity. However, increasing structural stiffness to achieve high resonance frequencies typically reduces electromechanical sensitivity. This work presents a finite element study of a coupled-resonator capacitive micromachined ultrasonic transducer (CMUT) designed to address this trade-off. The proposed architecture integrates three mechanically coupled silicon membranes with a stepped capacitive cavity that increases capacitance while preserving structural stiffness, enabling enhanced sensitivity without compromising high-frequency operation. COMSOL Multiphysics simulations were used to evaluate modal characteristics and frequency response under DC pre-stressed conditions. Modal coupling produced closely spaced resonances that broadened the effective bandwidth, while the stepped cavity significantly increased voltage output through improved electromechanical coupling. Compared to a single-resonator flat-cavity design, the coupled stepped-cavity configuration demonstrated nearly a threefold enhancement in output voltage while maintaining operation near 100 kHz. Additionally, adjusting the central resonator length enabled controlled frequency tuning for scalable array implementation. These results establish a proof of concept for a high-frequency, high-sensitivity micro-electro-mechanical systems (MEMS) CMUT architecture suitable for distributed AE monitoring in advanced manufacturing environments. Full article

This study proposes an effective method for realizing broadband-infrared (IR)-equivalent absorption using a metasurface constructed by shaping a metal–insulator–metal structure leading to a semi-opened nanocavity. The metasurface architecture is formed according to an optimized structural configuration and mature micro–nano-fabrication flow. Both the surface travelling and localized resonant wavefield accumulation excited by incident lightwaves in a broad wavelength range of 1–14 μm can be efficiently manipulated based on a dipole molecule antenna responding mechanism. An electromagnetic wavefield shielding effect within the semi-opened nanocavity and the standing-wave formation around the metasurface near-field based on an arrayed titanium–dielectric–titanium structure are examined in detail. The measured IR spectral absorption characteristics reveal that the metasurfaces based on an arrayed top titanium cap with the featured dimensions of 2.0 μm and 2.4 μm can be used to achieve an average equivalent IR absorptivity higher than 80% and 82%, respectively, across a broad wavelength range of 1.29–14 μm, which covers the traditional short-, medium- and long-wave IR bands. Full article

Surface Acoustic Wave (SAW) technology, long central to analog signal processing and RF filtering, is undergoing a major renewal. Driven by advances that decouple SAWs from traditional piezoelectric materials and fixed-function devices, the field is gaining unprecedented control over acoustic, optical, and electronic interactions at the micro and nanoscale. This review synthesizes these developments across four fronts: new physical mechanisms for SAW manipulation, emerging material platforms, ranging from thin films to 2D systems, along with reconfigurable device architectures and circuits, and the expanding landscape of applications they enable. Optical methods are reshaping how SAWs are generated and controlled, bypassing the limits of conventional electromechanical coupling. Coherent optical excitation of high-Q SAW cavities via Brillouin-like optomechanical interactions now grants access to modes in non-piezoelectric substrates such as diamond and silicon, while on-chip SAW excitation in photonic waveguides through backward stimulated Brillouin scattering opens new integrated sensing routes. In parallel, magneto-acoustic experiments have revealed nonreciprocal SAW diffraction from resonant scattering in magnetoelastic gratings. On the device side, ZnO thin-film transistors integrated on LiNbO₃ exploit acoustoelectric coupling to realize voltage-tunable phase shifters; UHF Z-shaped delay lines achieve high sensitivity in a compact footprint; and parametric synthesis of wideband, multi-stage lattice filters targets 5G-class performance. Atomistic simulations show that SAW propagation in 2D MXene films can be engineered via surface terminations, while aerosol jet printing and SAW-assisted particle patterning provide agile, cleanroom-light fabrication of microfluidic and magnetic components. These advances enable applications ranging from hybrid quantum systems and quantum links to lab-on-a-chip particle control, SBS-based and UHF sensing, reconfigurable RF front-ends, and soft robotic actuators based on patterned magnetic composites. At the same time, optical techniques offer non-contact probes of dissipation, and MXenes and other emerging materials open new regimes of acoustic control. Conclusively, they are transforming SAW technology into a versatile, programmable platform for mediating complex interactions in next-generation electronic, photonic, and quantum systems. Full article

Mechanical and thermal relaxation times are of utmost importance in determining the thermal quality of micro- and nano-resonators. The interplay between mechanical and thermal activity governs energy dissipation in these resonators. In a recent paper, an analytical thermal model was developed to incorporate mechanical and thermal relaxation times, thereby increasing the quality factor under mechanical damage, while accounting for static prestress in a micro-viscothermoelastic resonator. The effects of the relaxation time parameters and static prestress on the thermal quality factor have been addressed. This model assumes that static prestress can serve as a tuning knob for significant improvements in thermal efficiency variables. The mechanical and thermal relaxation times, isothermal frequency, and mechanical damage parameter have substantial effects on the resonator’s thermal quality factor. Full article

Mitigating the surface loss induced by subsurface damage is of critical importance in the manufacturing of fused silica devices with ultra-low mechanical loss. Chemical etching technology has been applied as an effective approach in controlling surface loss, while fundamental research on its mechanism is still lacking. In this work, chemical etching treatment on lapped fused silica samples was carried out for different periods of time. The evolution of surface micro-topography and roughness was observed. A set of apparatus for the Q-factor measurement was built, and an evaluation method for surface loss was proposed. The changes in the Q-factor and surface loss of samples during the etching process were demonstrated. The mechanism of surface loss induced by subsurface damage was revealed based on the friction of micro-interfaces. A surface loss model was derived from the definition of surface loss and the perspective of kinetic energy conservation. The results show that the surface micro-topography and roughness of samples depend on the evolution of subsurface cracks in etching. The Q-factor of samples is improved by about 50 times via chemical etching, from an initial value of 2.736 × 10⁵ to a maximum value of 1.338 × 10⁷. The subsurface-damage-induced surface loss of the sample lapped in this experiment is about 3.58 × 10⁻⁶, and most of the loss is caused by cracks in the near-surface layer. This work provides profound insights into the mechanism of surface loss caused by subsurface damage and holds guiding importance for the manufacture of fused silica resonators. Full article

In this work, a novel approach for implementing a resonant micro-accelerometer is demonstrated that may extend the operating frequency of such devices to several tens of MHz, which may enable direct wireless signal transfer. The proposed resonant accelerometer consists of a hybrid structure: a piezoelectric micro-resonator and a capacitive mass-spring (CMS) system (that are mechanically separated but electrically interconnected). The sensor utilizes the piezoelectric stiffening mechanism, which translates the acceleration-induced displacement of the capacitive mass-spring (CMS) structure into a shift in the resonance frequency of the interconnected resonator. The operating principle is elaborated upon in detail, supported by simulation and experimental results. Additionally, a novel fabrication technique is presented to realize a suspended fixed bi-layer electrode for the CMS in which a hardened layer of photoresist is utilized as a sacrificial layer. The experimental sensitivity of a fully functional device is reported to be ~6 Hz/g at 25 MHz (~0.23 ppm/g), which closely matches the simulated sensitivity of ~7 Hz/g (~0.278 ppm/g) for the fabricated capacitive gap of ~7 µm. Full article

Removing trace amounts of dissolved organic matter (DOM) has always been a significant issue in the field of environmental science and engineering. Herein, a UV-coupled O₃ micro-nano bubble (O₃-MNB) system was constructed, demonstrating superior efficiency in eliminating DOM compared to bulk O₃-MNB oxidation and direct UV photolysis. Various advanced analytical techniques, including in situ electron paramagnetic resonance, Fourier transform infrared spectroscopy and three-dimensional excitation–emission matrix, were employed to reveal the mechanism of the reaction process. Benefiting from the abundant interfacial area and enhanced mass transfer efficiency provided by the micro-nano bubbles, along with the simultaneous generation of reactive oxygen species such as •OH through UV activation, the UV/O₃-MNB system demonstrates excellent performance in removing DOM, and more than 90% of the mineralization rate was achieved after 1 h reaction. Furthermore, the findings were verified using both municipal water and natural surface water, and the proposed system also shows advantages in energy consumption compared to direct UV irradiation and conventional O₃ treatment, with an energy consumption of 25 kWh/mg dissolved organic carbon. This study innovatively integrates UV light with O₃-MNB technology, offering novel insights for advanced water purification and providing valuable references for practical engineering applications. Full article

The use of one-step products and their applications in sensory applications has gained much importance. Herein, Schiff’s base fluorescent turn-on sensor, namely FBTS, was synthesised via a condensation reaction between 6-fluorobenzo[d]thiazol-2-amine and 2-hydroxybenzaldehyde. The probe FBTS exhibits an intense “turn-on” blue fluorescence upon binding to Al³⁺ ions in a dimethyl sulfoxide–water (DMSO–H₂O (8:2, v/v)) medium. From photoluminescence (PL) titrations, the detection limit (LOD) for Al³⁺ is estimated to be 0.14 microM, and the Benesi–Hildebrand plot-based association constant (K_a) of 5.4 × 10⁴ M⁻¹ confirm a strong association between FBTS and Al³⁺. Negligible interference is observed in the presence of other metal ions. From the pH effect studies, the optimal pH range for Al³⁺ detection is 7–9. The recyclable reversibility of FBTS + Al³⁺ complex has been demonstrated via the sodium salt of ethylenediaminetetraacetic acid (Na₂-EDTA) chelation. A Job’s plot and interrogations, such as high-resolution mass spectrometry (HR-MS), ¹H-nuclear magnetic resonance (NMR) titration, and density functional theory (DFT), verified the 1:1 stoichiometry of binding between FBTS and Al³⁺. Based on multiple analyses, the binding mode and mechanism have been detailed. In addition, the practical application of FBTS for detecting Al³⁺ is demonstrated using the strip paper method, fish analysis, spiked real sample analysis, and cellular imaging. Full article