Coupling Structure Research Articles

Enhanced hydrogen production via catalytic water and urea oxidation in a hybrid acid-base electrolytic cell with NiFe-LDH/NiMoO4/NF

The construction of crystalline-amorphous coupling structure is one of the effective strategies to enhance the performance of oxygen evolution reaction (OER) and urea oxidation reaction (UOR). Herein, NiFe-LDH/NiMoO4/NF with high oxygen evolution and urea oxidation performance was successfully prepared by electrodeposition of amorphous substances on the crystalline precursor of hydrothermal synthesis. Remarkably, the NiFe-LDH/NiMoO4/NF displays exceptional electrocatalytic performance for OER and UOR, with a potential of only 1.57 V vs. RHE at 100 mA cm−2 and the Tafel slope of 54.4 mV dec−1 for OER, high UOR activity with a potential of 1.45 mV@100 mA cm−2 and the Tafel slope of 20.4 mV dec−1 in 1.0 M KOH with 0.33 M urea solution. In a hybrid acid-base electrolysis system for urea oxidation-assisted H2 production using NiFe-LDH/NiMoO4/NF as the anode electrode and Pt/C/NF as the cathode electrode, the process requires a cell voltage of only 0.55 V vs. RHE at 10 mA cm−2. Moreover, this hybrid acid/base system demonstrates stable operation for 110 h with minimal attenuation at a current density of 100 mA cm−2. These results indicate a facile strategy for the design of electrodes with crystalline-amorphous coupling structures for energy conversion.

Numerical simulation and in vitro experimental study of the hemodynamic performance of vena cava filters with helical forms

Inferior vena cava filter (IVCF) implantation is a common method of thrombus capture. By implanting a filter in the inferior vena cava (IVC), microemboli can be effectively blocked from entering the pulmonary circulation, thereby avoiding acute pulmonary embolism (PE). Inspired by the helical flow effect in the human arterial system, we propose a helical retrievable IVCF, which, due to the presence of a helical structure inducing a helical flow pattern of blood in the region near the IVCF, can effectively avoid the deposition of microemboli in the vicinity of the IVCF while promoting the cleavage of the captured thrombus clot. It also reduces the risk of IVCF dislodging and slipping in the vessel because its shape expands in the radial direction, allowing its distal end to fit closely to the IVC wall, and because its contact structure with the inner IVC wall is curved, increasing the contact area and reducing the risk of the vessel wall being punctured by the IVCF support structure. We used ANSYS 2023 software to conduct unidirectional fluid–structure coupling simulation of four different forms of IVCF, combined with microthrombus capture experiments in vitro, to explore the impact of these four forms of IVCF on blood flow patterns and to evaluate the risk of IVCF perforation and IVCF dislocation. It can be seen from the numerical simulation results that the helical structure does have the function of inducing blood flow to undergo helical flow dynamics, and the increase in wall shear stress (WSS) brought about by this function can improve the situation of thrombosis accumulation to a certain extent. Meanwhile, the placement of IVCF will change the flow state of blood flow and lead to the deformation of blood vessels. In in vitro experiments, we found that the density of the helical support rod is a key factor affecting the thrombus trapping efficiency, and in addition, the contact area between the IVCF and the vessel wall has a major influence on the risk of IVCF displacement.

Subjectivation through Structural Coupling – The Emergence of School Laggards and Deficient Pupils

This contribution explores how practices, concepts, and ideas about including and excluding pupils in schools are connected to different arenas of knowledge and how their inter-connectedness produced specific subject positions for pupils. By applying Niklas Luhmann’s concept of structural coupling as an analytical approach this article discusses the problem of non-promotion and the emergence of the “deficient child” to grasp the connections between the different social systems involved in these processes. Based on two case studies that deal with specific iterations of efforts to alleviate non-promotion, the contribution exemplifies how structural coupling can help to identify connections between and resulting activities in different social systems.

Improved efficacy of linear glutathione-peptide chaperon complexes on melanogenesis inhibition and transdermal delivery

Glutathione (GSH) exhibits considerable potential in the cosmetic industry for reducing intracellular tyrosinase activity and inhibiting melanin synthesis. However, its efficacy is hindered by limited permeability, restricting its ability to reach the basal layer of the skin where melanin production occurs. The transdermal enhancer peptide TD1 has emerged as a promising strategy to facilitate the transdermal transfer of proteins or peptides by creating intercellular gaps in keratinocytes, providing access to the basal layer. The primary objective of this study is to enhance the transdermal absorption capacity of GSH while augmenting its inhibitory effect on melanin. Two coupling structures were designed for investigation: linear (TD1-linker-GSH) and branched (TD1-GSH). The study examined the impact of the peptide skeleton on melanin inhibition ability. Our findings revealed that the linear structure not only inhibited synthetic melanin production in B16F10 cells through a direct pathway but also through a paracrine pathway, demonstrating a significant tyrosinase inhibition of nearly 70 %, attributed to the paracrine effect of human keratinocyte HaCaT. In pigmentation models of guinea pigs and zebrafish, the application of TD1-linker-GSH significantly reduced pigmentation. Notably, electric two-photon microscopy demonstrated that TD1-linker-GSH exhibited significant transdermal ability, penetrating 158.67 ± 9.28 μm into the skin of living guinea pigs. Molecular docking analysis of the binding activity with tyrosinase revealed that both TD1-linker-GSH and TD1-GSH occupy the same active pocket, with TD1-linker-GSH binding more tightly to tyrosinase. These results provide a potential foundation for therapeutic approaches aimed at enriched pigmentation and advance our understanding of the mechanisms underlying melanogenesis inhibition.

Self-Adaptive Resonance Technology for Wireless Power Transfer Systems to Eliminate Impedance Mismatches

Impedance mismatching can severely decrease the power transmission capacity or even invalid the control logic of wireless power transfer (WPT) systems. To eliminate the impedance mismatch caused by various factors, such as resonant parameter drift, coupling structure misalignment and control strategy, a self-adaptive mistuning correction circuit and corresponding parameter design rules are proposed to ensure the WPT system consistently operates under resonant state, accompanying the optimal power transfer ability. Moreover, a reactive compensation circuit that can create an auxiliary voltage source by the absorbed reactive power that is introduced by impedance mismatching is designed. This source can generate a new current on the coil to bring the mismatched input current back to the resonant state, according to the current superposition principle. Unlike passive impedance network that require high parameter precision and active impedance matching strategies equipped with detection and control circuits, the proposed approach can self-adaptively eliminate either undesired capacitive or inductive reactance with two additional switches and an energy-storage capacitor, improving impedance adjusting rate and providing better system robustness. The simulations and experiments are in good agreement with the theoretical analysis. This study has potential applications in harsh environments where the system impedance and coupling strength are continuously disturbed.

Design of a robotic gripper for casting sorting robots with rigid–flexible coupling structures

AbstractIn order to solve the problem of the insufficient adaptability of the current small- and medium-sized casting sorting robot gripper, we have designed a casting sorting robot bionic gripper with rigid–flexible coupling structures based on the robot topology theory. The second-order Yeoh model was used to statically model the clamping belt in the gripper to derive the relationship between the external input air pressure and the bending angle of the driving layer, and the feasibility of multiangle bending of the driving layer was verified by finite element analysis. The maximum gripping diameter of the gripper is 140 mm, and in order to test the adaptive gripping ability of the gripper, a prototype of the casting sorting robot gripper is prepared, and the pneumatic control system and human–machine interface of the gripper are designed. After several experimental analyses, the designed casting sorting robot gripper is characterized by strong adaptability and high robustness, with a maximum load capacity of 930 g and a maximum wrap angle of 296°, which can complete the gripping operation within 1 s, and the comprehensive gripping success rate reaches 96.4%. The casting sorting robot gripper designed in the paper can provide a reference for the design and optimization of various types of shaped workpiece gripping manipulators.

A coupled smoothed particle hydrodynamics–peridynamics model for two-dimensional hydroelastic water entry

In this paper, a numerical model coupling the smoothed particle hydrodynamics (SPH) with peridynamics (PD) is developed to solve the problem of the hydroelastic water entry. By combining the geometric nonlinear peridynamics with the weakly compressible SPH, the proposed model can efficiently simulate the nonlinear deformation of the structure and the deformation of a fluid free surface. The transmission of information between the fluid and solid phases is implemented by a dummy particle boundary treatment method. By simulating benchmark tests, the ability of the proposed model to solve nonlinear fluid–structure coupling problems is verified. In order to improve the computational efficiency, the graphics processing unit parallel acceleration scheme is applied to the SPH-PD model. Compared with the serial scheme, the speedup effect of the parallel scheme in large-scale computation is verified. As an application of the numerical model, the water entry of the flexible panel at a constant entry velocity is studied. The mechanism of hydroelastic effect is explained by analyzing the variations in the fluid pressure field, slamming force, and panel deformation during water entry. In addition, the influences of plate rigidity, impact velocity, and deadrise angle on the hydroelastic effect are investigated.

Free-Drop Experimental and Simulation Study on the Ultimate Bearing Capacity of Stiffened Plates with Different Stiffnesses under Slamming Loads

Differing from previous studies on free-drop tests, this study focuses on the ultimate bearing capacity and failure mechanism of the ship’s bow under slamming loads. A prototype ship’s bow is selected to design two simplified stiffened plates with different stiffeners, and the lateral slamming loads used are equivalent to flare slamming loads. Free-drop tests of the two simplified models are conducted, and the test setups and procedures are provided. The experimental results of slamming pressures and structural responses are obtained. By comparing with the simulation results obtained by Arbitrary Lagrangian-Eulerian (ALE) fluid–structure coupling, the convergence study, symmetry, and independence verifications are carried out. Finally, the dynamic ultimate bearing capacity of stiffened plates with different stiffnesses under lateral slamming loads is studied. The results show that stiffeners enhance the ability of stiffened plates to resist plastic deformation under slamming loads, and T-section stiffeners can provide greater resistance to plastic deformation than other types.

Mechanical characteristics of track slab and clamps during the pouring of self-compacting concrete in the China Railway Track System III slab track

The pouring of self-compacting concrete (SCC) is crucial for ensuring the construction quality and comfort of slab tracks. In this study, a fluid–structure coupling pouring model of SCC was established based on the coupled Eulerian–Lagrangian (CEL) approach. It was applied to trace the forces and displacements of track slab and clamps during SCC pouring. The influences of some key parameters, such as the pouring equipment, technology, and rheological properties, were investigated, including the height and diameter of the funnel, pouring velocity, and plastic viscosity of the SCC. The results indicated that during pouring, the floating force and maximum vertical displacement of the track slab, as well as the vertical forces of the clamps, initially remained stable before undergoing rapid changes, eventually reaching stable values. The flow velocity of SCC in the pouring hole and its rebound primarily influenced these mechanical indicators. The funnel height positively affected the floating force of the track slab, negatively affected the vertical forces of the clamps, and slightly affected the peak values of the maximum vertical displacement of the track slab. By contrast, the funnel diameter had little influence on these mechanical behaviour indicators. As the pouring velocity increased, the floating force of the track slab and vertical forces of the clamps significantly increased. Moreover, the peak values of the maximum vertical displacement of the track slab increased to 0.47 mm at a pouring velocity of 0.03 m/s. In the case of low plastic viscosity, an increase in plastic viscosity led to a visible decline in the floating and clamp forces. However, when the plastic viscosity exceeded 80 Pa•s, further changes had little effect on the mechanical indicators owing to the combined effects of excessively low flow velocity and rebounding.

Facile synthesis of hierarchical Fe–S co-doped carbon-based composites with superior microwave absorption

Difficulty of multi-component coupling and hierarchical pore structure preparation make it challenging to manufacture highly efficient microwave absorption materials (MAMs). Herein, hierarchical porous carbon composites anchored with various types of iron sulfides are successfully fabricated using a simply feasible heating-induced self-assembly approach. Controllable electromagnetic parameters and impedance matching features of FexSy/AC (amorphous carbon) composites are obtained by varying carbonization temperature. Besides, AC and FexSy provide dielectric and magnetic losses, while defect-rich AC can effectively disperse FexSy nanoparticles, exhibiting high sintering resistance and high-density interfaces, which contributes to polarization losses. Moreover, the unique hierarchical porous structure not only offers better impedance matching, but also enhances microwave loss. The thorough investigation indicates that FexSy/AC nanocomposites exhibit outstanding microwave absorption performance by the joint effect of unique hierarchical porous structure and coupling loss of multi-components. The optimal sample (FSC-700) shows a strongest reflection loss value of up to −78.96 dB with a matching thickness of 2.85 mm, an effective absorption bandwidth (EAB, RL<−10 dB) of 6.98 GHz (11.02–18.0 GHz, spanning Ku-band), and a radar cross section (RCS) reduction value of 21.75 dBm2. In addition, the EAB can reach 13.8 GHz with the simulated thickness varies from 1.0 to 5.5 mm, covering 86 % of the measured frequency range. The in-depth research of the multi-component system with hierarchical porous structure offers an innovative and practical method for high-performance MAMs.

Self-Referential Plasmonic Refractive Index Sensor by Square Hole Array and Gold Film Coupling Structure

Self-Referential Plasmonic Refractive Index Sensor by Square Hole Array and Gold Film Coupling Structure

Liquid metal-based flexible heat sink for adaptive thermal management

The deformable heat sinks are critical for flexible electronics, wearable personal thermoregulation and energy management. However, the available soft polymer materials with poor thermal characteristics face challenges in achieving efficient heat transfer. Herein, we report an excellent flexible heat sink enabled by a gallium-based liquid metal (LM) for adaptive thermal management. The flexible heat sink is prepared by embedding LM droplets and copper particles into the elastic matrix forming solid–liquid multiphase composites, achieving a considerable thermal conductivity (3.5 W/mK@300 % stretching deformation), outstanding high-temperature resistance, and excellent conformity. The cooling and hydrodynamic characteristics of the flexible heat sink with different structures, including parallel (plane), S-type (plane), and annular (three-dimensional) channels, are investigated and optimized by the thermal experiment and developing the fluid–structure coupling numerical simulation. The results show that the maximum temperature and heat flux achieved by the S-type heat sink are 36.7 °C and 0.68 W/cm2 respectively, due to the secondary flow enhancing convection thermal transfer intensity. The annular heat sink has outstanding advantages in suppressing temperature and improving uniformity because the thermal transfer path is optimized by stretching, especially for larger deformation. Furthermore, the annular heat sink has been proven feasible for lithium battery cooling and pre-insulation.

Weakly coupled photonic flexible sensors based on sodium polyacrylate

The flexible optical fiber sensor serves as a prototype for highly sensitive photonic skin flexible sensors (PSFS) with rapid response times, facilitating the development of advanced wearable healthcare devices. Future bionic skin sensors, tailored for wearable devices focusing on health monitoring and robotics applications, will necessitate the incorporation of optical systems. In this work, PSFS based on weak coupling structure is proposed for the first time. This structure comprises a fiber optic sensor with weak coupling as the core sensing node, and the sensing material is hydrophilic and flexible sodium polyacrylate (SPA). The SPA combines the high sensitivity of PSFS with excellent biocompatibility, enabling both static and dynamic sensing measurements for physical parameters such as humidity and temperature. Leveraging the strain amplification effect of the single-mode tapered fiber and the unique fiber structure, the material's sensitivity to relative humidity (RH) is significantly enhanced, reaching 0.19 dB/%RH. Furthermore, the temperature response demonstrates exceptional sensitivity (0.29 dB/℃) within the range of human skin surface temperatures (30–48℃). Remarkably, the sensor has a significant response time of 128 ms. This research proposes a novel approach for constructing highly sensitive and versatile PSFS, which is critical for health care monitoring.

Evolution of Telencephalon Anterior-Posterior Patterning through Core Endogenous Network Bifurcation.

How did the complex structure of the telencephalon evolve? Existing explanations are based on phenomena and lack a first-principles account. The Darwinian dynamics and endogenous network theory-established decades ago-provides a mathematical and theoretical framework and a general constitutive structure for theory-experiment coupling for answering this question from a first-principles perspective. By revisiting a gene network that explains the anterior-posterior patterning of the vertebrate telencephalon, we found that upon increasing the cooperative effect within this network, fixed points gradually evolve, accompanied by the occurrence of two bifurcations. The dynamic behavior of this network is informed by the knowledge obtained from experiments on telencephalic evolution. Our work provides a quantitative explanation for how telencephalon anterior-posterior patterning evolved from the pre-vertebrate chordate to the vertebrate and provides a series of verifiable predictions from a first-principles perspective.

Time-Varying Aeroelastic Modeling and Analysis for a Morphing Wing

The paper presents a novel time-varying aeroelastic modeling approach for the morphing wing with the process of camber changing. The time-varying modeling methodology includes structural dynamics modeling, unsteady aerodynamic modeling, and interpolation for fluid–structure coupling. Firstly, the morphing wing is modularized and divided into fixed and variable parts by the floating frame of reference formulation. It is combined with the Craig–Bampton method to reduce order and eliminate nonindependent degrees of freedom. Then, the unsteady vortex-lattice method is used to calculate the transient, unsteady aerodynamic force for time evolution. Furthermore, the above time-varying structural dynamics modeling and a fluid–structure coupling interpolation are integrated to construct overall aeroelastic modeling, obtaining a set of differential-algebraic equations. Finally, these equations are numerically solved by the generalized-α method. The proposed approach provides an innovative idea to deal with the incredible complexity of the aeroelastic effect as structural characteristics change over time. It can efficiently and accurately analyze the morphing wing’s transient response or flutter property. To verify and utilize the time-varying aeroelastic modeling approach, numerical calculations and comparative studies were carried out regarding the time-varying characteristics of the structural modes, aerodynamic calculations, and flutter prediction of the morphing wing.

Creating absolute band gap based on frequency locking of three wave modes in a wavy plate

This paper presents an absolute band gap (BG) by overlapping coupled band gaps based on frequency locking mechanism within a wavy structure. We first introduce coupled BG’s trigger conditions, including weak coupling, and then utilize two coupling in a wavy structure to lock three wave modes into two overlapped coupled BGs. A wavy specimen is determined for experimental validation, by selecting the geometric parameters based on their individual effects on the coupled BG. Four testing loads with the capability to excite all guided waves are applied numerically and experimentally to verify the performance of the absolute BG. The response signals validate the existence of a wide attenuation band introduced by the absolute BG. The results exhibit a great potential for utilizing the frequency locking mechanism to construct an absolute BG for applications such as vibration control.

Damage evolution in layered rock masses of a mining floor under the influence of fluid–structure coupling

AbstractCurrent research on rock damage in mining floors primarily focuses on the seepage‐stress coupling effect, overlooking the fact that rock masses in coal measure strata are predominantly layered. To address this gap, cyclic loading and unloading triaxial tests were conducted. Additionally, theoretical analysis, mathematical statistics, and other methods were used to investigate the damage evolution law of layered rock masses in coal measures. This investigation was carried out under the coupled effects of a specific stress path, characterized by ‘stress concentration‐stress unloading‐stress recovery’, and a high confined water seepage field. The results show that the compression modulus increases with the increase in confining pressure and osmotic pressure, but its increasing trend gradually slows down. Within a certain range, increasing the confining pressure and osmotic pressure helps to close rock fractures and increase stiffness.

Role of cilia activity and surrounding viscous fluid in properties of metachronal waves.

Large groups of active cilia collectively beat in a fluid medium as metachronal waves, essential for some microorganisms motility and for flow generation in mucociliary clearance. Several models can predict the emergence of metachronal waves, but what controls the properties of metachronal waves is still unclear. Here, we numerically investigate the respective impacts of active beating and viscous dissipation on the properties of metachronal waves in a collection of oscillators, using a simple model for cilia in the presence of noise on regular lattices in one and two dimensions. We characterize the wave using spatial correlation and the frequency of collective beating. Our results clearly show that the viscosity of the fluid medium does not affect the wavelength; the activity of the cilia does. These numerical results are supported by a dimensional analysis, which shows that the result of wavelength invariance is robust against the model taken for sustained beating and the structure of hydrodynamic coupling. Interestingly, the enhancement of cilia activity increases the wavelength and decreases the beating frequency, keeping the wave velocity almost unchanged. These results might have significance in understanding paramecium locomotion and mucociliary clearance diseases.

Graphene-based tunable broadband metamaterial absorber for terahertz waves

In order to overcome the limitations exhibited by traditional absorbers in electromagnetic wave absorption, such as the extremely narrow absorption bandwidth and uncontrollable absorption results, this paper proposes a novel tunable broadband metamaterial absorber based on graphene. Compared to other terahertz absorbers, the absorber designed in this study exhibits simpler structural design, compact form, thin thickness, efficient absorption performance, and a broader bandwidth. This absorber adopts a three-layer structure, including a patterned monolayer graphene metasurface, a dielectric layer, and a metal substrate. The structure of this patterned graphene consists of four triangular graphene resonators, achieving both high absorption efficiency and maintaining an exceptionally wide absorption bandwidth. The simulation results indicate that at a Fermi energy level Ef of 0.45 eV, the absorber achieves a broadband absorption rate of over 90 % in the 3.287 THz to 5.247 THz frequency range under normal terahertz wave incidence conditions. By analyzing different quantities of the triangular graphene structure on the top of the absorber, we found that the wide absorption bandwidth of the absorber is mainly attributed to the structural coupling of the top-layer graphene in the absorber. Furthermore, through the study of electric field amplitude and current distribution, we stumbled upon that when terahertz waves are incident on the absorber, due to the structural coupling between the graphene layers, electric resonance and magnetic resonance occur within the absorber, resulting in the absorption effect. Finally, through the study of geometric parameters, different polarization angles and oblique incidence angles of the incident waves, as well as different Fermi energy levels of graphene, we discovered that by adjusting the Fermi energy level of graphene, the bandwidth and absorption performance of the absorber can be flexibly tuned. In addition, this absorber exhibits wide-angle absorption characteristics and polarization-insensitive properties, providing potential application prospects in fields such as terahertz thermal imaging and stealth technology.

The Auditory Dimension of the Technologically Mediated Self

Abstract In this article, I aim to clarify some of the ways in which the auditory dimension of the self is constituted through the mediation of technology. I show that by excluding our immediate surroundings with mobile personalized and private auditory technologies, we are increasingly laying down a personal, inner spatial grid of acoustic memories that get integrated into our narrative identity and co-constitutes the space of familiarity and belonging that gives us a sense of who we are. To do so, I first lay out a clear ontological ground. Next, I outline how the auditory dimension of the self is constituted and subsequently mediated technologically. Finally, I bring to bear Erving Goffman’s theatrical framework of performative self-constitution as a useful framework to illustrate how, on one hand, the culturally available repertoire on which the imagination draws to constitute the self has augmented thanks to the contributions of other people in distal spatiotemporal contexts; on the other, the reconfiguration of how we listen to the world and the other people in it entails muting or blocking out of other voices. This can stunt how we conceive of ourselves, producing an epistemic bubble involving a tunnel “vision” or echo-chamber effect. In addition, due to the coupling of bodily and cognitive structures with mobile, privatized auditory technologies that thereby become transparent in experience, others, by listening in on us, acquire the ability to privilege certain types of behavior while suppressing others. Thus, there is a danger that the individual autonomous agency so important to self-constitution can be compromised.