Search Results (2,013)

To develop an analysis-oriented stress–strain model for prestressed fiber-reinforced polymer (FRP)-confined circular concrete, the path-dependent responses of prestressed FRP-confined concrete and actively confined concrete were systematically investigated. Existing experimental data were used to examine the applicability of the stress-path independence and strain-path independence assumptions under different prestressing methods. The filament winding method generally satisfies the stress-path independence assumption, with relative errors in axial stress mostly within 10%, whereas direct application of the actively confined concrete model to expansive-concrete method specimens results in errors close to 20%. After accounting for the initial confinement effect, these errors are generally reduced to within 10%. Strain-path comparisons further show that the prestress-induced initial lateral strain should be considered; after removing this initial strain component, the lateral strain–axial strain relationship shows strong consistency with that of actively confined concrete. Accordingly, the peak stress, peak strain, and lateral strain–axial strain relationship were modified, and a strain-controlled incremental calculation procedure was established to generate the complete stress–strain response. Validation against compiled published experimental data yielded an R² of 0.931 and a MAPE of 8.88% for compressive-strength prediction, while the predicted axial stress–strain and lateral dilation responses also showed reasonable agreement with the experimental results. The proposed model can therefore support nonlinear analysis over the complete loading range and quantitative assessment of strength and deformation for different prestress levels and FRP confinement parameters within the validated range. Full article

While ion correlation is known to enhance molecular-scale solvation forces, its capacity to improve macroscale boundary lubrication on engineering surfaces remains unverified. This study demonstrates that multivalent electrolyte-induced ion correlation significantly reduces macroscopic boundary friction, achieving up to a 67% reduction on alumina surfaces. This macroscopic enhancement is driven by interfacial electrochemical properties, where highly charged polar oxide interfaces trigger strong electrostatic correlation to restructure confined solvents into a rigid, load-bearing barrier. Ultimately, this work proves that interfacial ion correlation directly dictates and enhances macroscale boundary lubrication, bridging molecular-level force control with practical tribological applications. Full article

The deformation and failure mechanism of deep mudstone under high temperature and high pressure (HTHP) is a critical issue constraining deep-drilling efficiency. Taking an HTHP mudstone formation in the western South China Sea as the research object, this study integrates X-ray diffraction, scanning electron microscopy, nanoindentation, HTHP triaxial compression tests, and FDEM numerical modeling incorporating mineral heterogeneity and Weibull strength distribution. The mudstone is predominantly composed of clay minerals (44.67%) and quartz (32.37%), with low hardness (1.42–2.96 GPa) and moderate elastic modulus (43.9–58.2 GPa). Under ambient conditions, uniaxial compressive strength is approximately 19.5 MPa with axial splitting failure; at 40 MPa confining pressure, strength increases to 121.8 MPa with shear failure; at 150 °C and 40 MPa, peak strength slightly decreases, yield point is delayed, and post-peak decline accelerates. The FDEM model, calibrated against experimental data, reasonably reproduces crack evolution and failure modes. However, due to limited tests (one per condition) and variations in specimen depth, statistical robustness is constrained; thus, this study does not yet establish a generalizable quantitative cross-scale correlation, and the findings are primarily applicable to the specific formation investigated. Full article

In this paper, we report a metal-driven structural tuning strategy with the L-histidine (His) ligand to modulate peroxidase-like nanozyme performance. Although the His coordinates with gold(III) ions to form an extended helical coordination polymer, its interaction with Cu(II) ions results in quantum-confined, ultrasmall nanoclusters. Based on the optical, structural, and surface analysis, the blue-emitting cores are stabilized by His ligands through imidazole nitrogen coordination, consistent with a Cu-centered coordination environment involved in the observed catalytic activity. According to the catalytic measurements, the His-Cu clusters outperformed the His-Au coordination polymer reference system. Steady-state kinetic modeling and 3D profiling revealed a pronounced shift in the pH optimum: low-valent Cu-containing His-Cu NCs enable efficient peroxide-dependent catalysis under nearly neutral conditions (pH 7.4), whereas His-Au CP exhibits its maximum activity under acidic conditions. Based on these findings, this work highlights nanoscale engineering for tailor-made biomimetic applications. Full article

Electrochemical impedance spectroscopy (EIS) resolves the internal physicochemical processes of lithium-ion batteries across timescales—from ohmic conduction through charge-transfer kinetics to solid-state diffusion. Despite this analytical power, EIS deployment remains largely confined to laboratory electrochemical workstations that are bulky, expensive, and incapable of online multi-cell operation under dynamic DC bias conditions. This study presents a multi-channel EIS measurement device that simultaneously addresses three requirements for practical battery diagnostics: workstation-grade measurement accuracy, multi-cell synchronous acquisition, and tolerance to the DC bias voltage present across battery terminals during operation. The device employs a master–slave distributed architecture: each slave unit is built around the DNB1101 battery-dedicated impedance measurement chip with a Kelvin four-wire sensing configuration, while the STM32F407-based master controller coordinates measurement scheduling and data communication under FreeRTOS. A four-channel slave board with a differential daisy-chain communication topology and hardware broadcast trigger mechanism supports multi-cell synchronous acquisition. The device operates over a frequency range of 0.01 Hz to 5620 Hz with logarithmic spacing, and a C#-based host application provides real-time Nyquist and Bode visualization along with MATLAB R2024a-based post-processing for outlier rejection and data smoothing. Validation was conducted using Panasonic NCR18650 ternary (NCA) and LiFePO₄ (LFP) 18650 cells, benchmarked against a CorrTest CS350 electrochemical workstation at SOC = 40% and 25 °C. The device achieves a maximum impedance magnitude error of 1.55% and a maximum phase error of 1.22%. Equivalent circuit model fitting via ZSimpWin yields parameter differences below 1% between the device and the reference workstation. Under online conditions with a 3.6 V DC bias, the impedance measurement deviation of a 20 mΩ precision resistor remains below 0.69% across the full frequency range. Multi-channel synchronous measurements across four cells demonstrate inter-channel amplitude variance below 2.13%. Cross-chemistry validation with LiFePO₄ cells yields magnitude and phase errors below 0.92%. These results demonstrate that the proposed device provides laboratory-grade EIS accuracy with multi-channel, online, and cross-chemistry capabilities, offering a practical platform for integrating EIS-based diagnostics into next-generation battery management systems. Full article

Background: Cell migration is a biological process influenced by biochemical signals and mechanical stimuli from the microenvironment. In this context, the accurate characterization of the mechanical microenvironment generated within microfluidic platforms represents an essential step for the design and interpretation of cell migration studies. Understanding how hydrodynamic forces influence the mechanical microenvironment experienced by cells remains a challenge, especially in confined and biomimetic systems. Methods: In this study, a three-dimensional microfluidic device was developed in silico to characterize the effects of flow variation on mechanofluidic parameters and to provide a quantitative basis for designing future cell-migration experiments. Computational fluid dynamics simulations were performed to characterize the velocity, pressure, and wall shear stress (WSS) distributions under different inlet flow rates (0.5, 1, and 5 µL/min) and three distinct inlet/outlet configurations within the same three-dimensional geometry. Rigid hemispherical probe structures were incorporated into the model to quantify the local shear stress acting on cell-sized surfaces. Results: The results demonstrated a direct and linear relationship between the applied flow rate and the WSS, modulated by the channel geometry and the inlet and outlet configuration. Regions near micropores and lateral channels showed high WSS values, while central regions experienced less mechanical stimulation, depending on flow conditions. Comparison with WSS values and ranges associated with cellular responses reported in the literature indicated that certain operational configurations generated mechanical conditions comparable to those previously investigated in cell-based studies, including cell migration applications. Conclusions: Overall, the study highlights the importance of controlling flow conditions in microfluidic platforms and provides a quantitative basis for the development and optimization of three-dimensional microfluidic devices intended for designing future cell-migration experiments. The systematic comparison of three inlet/outlet configurations across three flow rates within the same three-dimensional geometry provides a comparative framework for identifying configuration-dependent changes in the local mechanofluidic environment, supporting the selection of operational conditions for future mechanobiological and cell-migration studies. Full article

Canopy 3D architecture is a critical determinant of light interception, photosynthetic efficiency, and final yield in cotton, yet its rapid and accurate characterisation remains challenging in field conditions. To achieve efficient, non-destructive, and quantitative monitoring of the canopy structure of field-grown cotton, this study proposes a 3D structure-based technology stack for high-efficiency, low-cost, and high-precision phenotyping extraction. This stack directly addresses the technical bottlenecks of traditional 3D data acquisition, namely high cost, long processing time, and low operational efficiency, which have hindered large-scale application. We developed a pipeline that integrates a fast reconstruction algorithm with a scale-recovery mechanism using ground control points (GCPs), enabling the generation of true-scale 3D point clouds from UAV aerial images in a cost- and time-effective manner. Using only 141 UAV images and with a reconstruction time of approximately 20 min, we efficiently reconstructed high-quality, scale-accurate point clouds of two 5.5 m × 5.5 m cotton plots, significantly outperforming SfM-MVS and Instant-NGP in terms of both reconstruction efficiency and point cloud completeness. This method, whose current validation is confined to a single season, one growth stage, and two experimental plots, not only achieves a breakthrough by using fewer input images with high efficiency, but also ensures point cloud accuracy and completeness, showing strong potential for rapid field monitoring and real-time management. Based on the high-quality reconstructed point clouds, we further quantitatively evaluated canopy characteristics at harvest, analyzing the coefficient of variation of canopy height, porosity distribution, and canopy volume fraction. The core shortcomings and optimization strategies for the existing canopy structure were identified, providing scientific data support and practical technical references for precision cultivation management and mechanization-compatible planting in cotton. Full article

Natural wood possesses a hierarchically porous and anisotropic structure, which provides a foundation for functional utilization, but its flammability and hygroscopicity limit its applications. Conventional bulk impregnation modification involves introducing functional agents throughout the entire pore system. This approach can enhance performance, but inevitably leads to lumen occlusion and increased density. To address this trade-off, researchers have recently developed micronano coating strategies based on interfacial decoration rather than bulk deposition within the lumina. These strategies confine functional components to cell wall surfaces while preserving the natural porous scaffold. Two fabrication routes have been developed, namely liquid-phase methods and gas-phase methods, which differ in coating precision, penetration depth, and interfacial bonding. In flame retardancy, interfacial coatings act as physical barriers and promote chemical charring. Inorganic layers suppress oxygen diffusion and heat transfer, while phosphorus or nitrogen components catalyze cellulose dehydration. In acoustics, conformal coatings regulate pore wall roughness and acoustic impedance, enhancing viscous and thermal dissipation without blocking channels. Challenges for practical application include mass transfer limitations in large logs, conflicts between high-precision processes and industrial economics, and interfacial durability under service conditions. This narrative review summarizes fabrication strategies, flame-retardant mechanisms, and acoustic regulation principles, providing guidance for coating strategy selection and process optimization. It is noted that this review focuses on wood species with open, permeable pore structures suitable for functional modification, rather than species whose pores are occluded by heartwood extractives. Full article

Tapered optical fiber-based surface-enhanced Raman scattering (SERS) probes have emerged as promising miniaturized platforms for chemical and molecular sensing by integrating optical excitation, plasmonic enhancement, and Raman signal collection within a single fiber architecture. Their enhanced light–matter interaction, compact geometry, and remote interrogation capability make them particularly attractive for in situ sensing in confined and complex environments. This review systematically examines recent advances in tapered optical fiber SERS probes, covering enhancement mechanisms, taper fabrication, plasmonic hotspot engineering, and analytical applications. Particular emphasis is placed on how taper geometry and plasmonic nanostructure organization jointly influence sensing performance. Fabrication and hotspot-engineering strategies are critically compared in terms of sensitivity, reproducibility, stability, fabrication complexity, and scalability. Representative applications in biomedical analysis, food safety, and environmental monitoring are further evaluated. Despite these advances, practical implementation remains constrained by insufficient hotspot reproducibility, quantitative reliability in complex matrices, long-term stability and antifouling performance, as well as the limited scalability of current fabrication protocols. Future progress will require balancing analytical sensitivity with reproducibility, robustness, and real-sample compatibility, while advancing deterministic hotspot engineering, selective recognition interfaces, standardized performance evaluation, intelligent spectral analysis, and Lab-on-Fiber integration. Together, these developments could accelerate the transition of tapered optical fiber SERS from laboratory-scale demonstrations to field-deployable platforms for remote and in situ molecular sensing. Full article

Tensegrity structures, due to their lightweight and self-equilibrating characteristics, have found extensive applications across various engineering fields. The introduction of equal cable length as an additional geometric constraint enables a high degree of geometric symmetry, resulting in uniform internal force distribution and predictable mechanical responses. However, existing stiffness matrix assembly methods predominantly rely on conventional node-element topological connectivity matrices confined to classical one-to-one force-displacement systems, struggling to exploit the geometric regularities inherent in equal-length constraints and highly symmetric configurations. To address this, the paper proposes a stiffness matrix modeling method tailored for equal-cable-length tensegrity structures within the linear stiffness framework. A generalized connectivity matrix is introduced to unify the topological description of struts and cables while integrating displacement compatibility, internal equilibrium, and geometric constraints into a cohesive algebraic system. Leveraging symmetry properties and member categorization by loading type, the method embeds equal-length and symmetry grouping information directly into assembly, significantly reducing independent variables and construction complexity. A finite element model is established for numerical implementation, and experiments on a three-bar tensegrity structure validate the theoretical model, with minor deviations confirming its reliability. Full article

The limitations of conventional inorganic electrodes call for organic alternatives for advanced energy storage. Metal–covalent organic frameworks (MCOFs) integrate the metal active sites of metal–organic frameworks (MOFs) with the high chemical stability imparted by strong covalent bonds in covalent organic frameworks (COFs) while retaining the high specific surface area and tunable porosity of both material classes. Among these, MCOFs constructed from porphyrin and phthalocyanine building units have emerged as a research hotspot in electrochemical energy storage owing to their inherent 18π-conjugated macrocyclic electronic systems, well-defined M–N₄ coordination sites, and potential bipolar charge storage characteristics. This review systematically summarizes recent advances in this class of materials. First, from the perspective of metal center introduction timing, three core synthetic strategies—pre-metallation, simultaneous metallation, and post-metallation—are categorized and evaluated in terms of coordination precision, synthetic efficiency, and scalability potential. Second, the regulatory effects of two-dimensional layered and three-dimensional interpenetrated structures on charge transport pathways and structural stability are elucidated. Subsequently, the applications of porphyrin/phthalocyanine-based MCOFs in lithium-based batteries, zinc-based batteries, sodium/potassium-ion batteries, and supercapacitors are reviewed in detail, with emphasis on the key roles of metal active sites in catalytic conversion, chemical anchoring/confinement, interface stabilization, and pseudocapacitive contribution. Finally, future directions to address key performance and mechanistic bottlenecks are discussed. This review aims to provide a systematic reference for the rational design and energy storage applications of high-performance porphyrin/phthalocyanine-based MCOFs. Full article

This study demonstrates that supercritical carbon dioxide phase-change fracturing technology can reduce acute pressure-related injury potential compared to conventional explosives in underwater reef clearance operations along the Yangtze River. Employing a stepwise “pipe test, numerical simulation and engineering application” framework, a novel rock–water–fish coupled HJC–Gruneisen elastoplastic model was established to simulate cross-medium shock wave attenuation processes. The supercritical CO₂ shock wave exhibits characteristics of “low peak overpressure (13% of equivalent explosives) and long duration (6–7 times longer than conventional explosives),” attenuating in water with a power-law index α = 0.717. A dual-parameter “resistance line (intact rock buffer between the fracturing tube and the rock–water interface)–water depth” correction model indicates that the resistance line reduces peak overpressure by 18.6%, while each 10 m increase in water depth enhances attenuation by 60.6%. The preliminary engineering critical safety threshold for 30 cm silver carp (indicated by swim bladder rupture) is 0.20 MPa. Based on the representative engineering scale of the Chaofu Waterway Regulation Project, characterized by water depths of approximately 6–16 m and a resistance-line-controlled buffer condition, a theoretical safety distance model R_safe was also derived. Under these engineering constraints, the application results indicate that the lethal zone was confined to 7.5–9.9 m, enabling precise lethal-injury-safe zoning. This work establishes a fish injury threshold and safety assessment system for supercritical CO₂ subaquatic fracturing, providing direct green guidelines for Yangtze River navigation projects. Full article

Mycotoxin contamination remains a persistent threat to food and feed safety owing to the chemical stability of many mycotoxins, frequent co-occurrence, and matrix-dependent risks. Enzymatic detoxification enables structure-targeted transformation of toxicity-determining motifs, such as epoxide rings, reactive double bonds, amide linkages, and lactone structures. However, free mycotoxin-degrading enzymes are often constrained by poor operational stability, difficult recovery, and limited adaptability to complex matrices. Metal–organic frameworks (MOFs) provide programmable microenvironments for enzyme immobilization through tunable pore structures, interfacial chemistry, and confinement effects. This review links toxic structural motifs with enzymatic transformation targets, discusses MOF–enzyme interface engineering and representative host–enzyme compatibility, and evaluates application modes including single-enzyme systems, multi-enzyme co-immobilization or cascade systems, adsorption–degradation coupling, and detection–degradation integration. Key bottlenecks involving enzyme leakage, mass-transfer limitation, real-matrix stability, scalable preparation, and biosafety are critically discussed. Rather than treating MOFs as passive enzyme carriers, this review proposes an application-oriented framework that integrates toxin structure, enzyme function, MOF interface regulation, matrix compatibility, and safety validation to guide the development of MOF-immobilized degrading enzymes for practical mycotoxin detoxification. Full article

Graphite-based nanocomposites with nitrogen-rich covalent two-dimensional materials are promising for energy, catalytic and sensing applications, but their controlled construction remains challenging because both graphite and many covalent 2D materials consist of stacked sheets that are difficult to integrate homogeneously without prior exfoliation, dispersion, mixing, and restacking. Here, we explore a solvent-free strategy that uses melamine-confined graphite as a preorganized precursor for chemical transformations between graphene layers. We demonstrate that intercalated melamine can undergo reaction pathways analogous to those of bulk melamine, enabling not only the previously reported formation of graphite/g-C₃N₄ composites but also the construction of a new graphite/melem composite. The same concept is further extended to multicomponent solid-state reactions by introducing pyromellitic dianhydride, enabling the formation of new graphite/polyimide-linked two-dimensional material composites from either melamine or melem precursors. Comparison of one-pot and stepwise routes shows that precursor preorganization within graphite improves framework preservation, structural continuity, and morphological homogeneity. Overall, this work presents graphite interlayers as confined reaction environments for transforming simple nitrogen-rich molecules into integrated graphite/2D-material composites, providing a scalable platform for exploring solid-state chemistry and hybrid material synthesis between graphene layers. Full article

InGaN/GaN quantum wells on polar substrates exhibit a pronounced quantum-confined Stark effect, which significantly limits their efficiency as light emitters. Surprisingly, this detrimental effect is significantly reduced when wider wells (above 10 nm) are used; their emission kinetics are the central focus of this work. A time range spanning nine orders of magnitude, from picoseconds to milliseconds, is explored through various experiments. This includes experiments on the optical visualization of slow decays of charge in the ground states (called “dark charge”) in the millisecond range, experiments on radiative recombination of excited states in the nanosecond range, and experiments on the relaxation of hot carriers in the picosecond range. All data are explained within the framework of qualitative and semi-quantitative models. The highly diverse kinetics of ground and excited states are due to the fact that the ground states of electrons and holes have negligible overlap and screen the built-in field, are optically inactive, and recombine nonradiatively in milliseconds. Meanwhile, when the field is screened, the excited states recombine radiatively in the picosecond/nanosecond ranges. The pulses of photo- and electroluminescence depend strongly on the excitation period. The application of negative-voltage pulses allows us to deplete the well of charge and generate short pulses of light. Full article