Heterogeneous Coupling Research Articles

A {Ru(C6H6)}-Containing Isopolymolybdate with Good Photocatalytic Activity for Oxidative Coupling of Amines, and Proton Conduction Properties.

We present a nonclassical {Ru(C6H6)}-containing isopolymolybdate Cs8K2Na2H4{[(C6H6)Ru]6Mo24O86}·35H2O (1) via one-pot reaction. The crystallographic characterization of compound 1 revealed that it contains an unusual {Mo24O86} cluster together with six {Ru(C6H6)} groups, having the largest number of {Ru(C6H6)} groups within the field of {Ru(C6H6)}-containing polyoxometalates. Results showed that compound 1 displayed excellent proton conductivity (9.8 × 10-3 S cm-1) at 90 °C and 95% relative humidity. Based on the calculation result of activation energy, which was more than 0.4 eV (1.47 eV), it was determined that the proton conduction process for compound 1 was in accordance with the Vehicle mechanism. More interestingly, compound 1 was exploited as a catalyst to achieve the heterogeneous oxidative coupling of amines and realized a high yield (98.9%) toward N-benzylidenebenzylamine under ambient temperature and visible light irradiation (>400 nm) and O2 atmosphere.

Enhanced Heterogeneous Interfacial Coupling of NiCoS@NiCo(CH3COO)x as Efficient and Long-term Stable Electrocatalysts for Oxygen Evolution Reaction

Enhanced Heterogeneous Interfacial Coupling of NiCoS@NiCo(CH₃COO)_<i>x</i> as Efficient and Long-term Stable Electrocatalysts for Oxygen Evolution Reaction

Modeling and experiment for the roller hemming of variable curvature aluminum alloy panel with adhesive

The autobody closures have high requirements on the appearance accuracy of A-class surfaces, smooth contours, and continuous edges, so the forming quality of the autobody closures has long been the center of attention in the roller hemming process. To facilitate weight reduction in automotive manufacturing, lightweight materials such as aluminum alloy and hemming adhesive are commonly used. However, the heterogeneous coupling effect between the adhesive and aluminum alloy panel during roller hemming can significantly influence the forming quality of the panel. Additionally, the precision of the roller posture and trajectory plays a crucial role in determining the final quality of the panels, given the complex geometry of the autobody closures. Therefore, in order to continuously improve the forming quality of the autobody closures, this paper investigates the roller hemming process applied to variable curvature panel with adhesive on autobody doors. Firstly, the kinematic model for the roller posture and trajectory during roller hemming of the curved surface-curved edge panel was developed based on differential geometry theory. Secondly, a simulation model for roller hemming of the panel with adhesive was established using the finite element method and the smoothed particle hydrodynamics method (FEM-SPH). The validity of the simulation was confirmed by comparing the simulated results with experimental outcomes. In the experiment, the algorithm for solving the posture and trajectory of the roller was applied, and the forming quality of the panel was evaluated by using the two indexes of roll-in/out coefficient and surface wave coefficient. Thirdly, the impact of the hemming factors on surface wave and roll-in/out was analyzed using the response surface methodology, leading to the development of a mapping relationship between the hemming factors and forming quality. This study provides valuable support for predicting the forming quality of variable curvature panels with adhesive and continuously improving the forming quality of autobody closures in the roller hemming manufacturing process.

Multi-scale FE analysis of coupled load-moisture mechanical behavior of saturated asphalt pavements considering transversely isotropic permeability

Assessing the collective impacts of external loading and void pressure on the mechanical behavior of porous media presents a significant challenge due to its inherent heterogeneity and complex multi-physical field coupling mechanisms. This study addresses this challenge by developing a novel multiscale hydraulic-mechanical modeling framework to investigate the structural response of water-saturated asphalt pavement under sequential coupling hydro-mechanical loading. The framework comprises three key components. Firstly, incorporating an upscaling homogenization approach to establish the linkage of material properties between different scales; secondly, developing a downscaling transfer procedure to transfer the structural response across scales for insight into its multiphysics mechanisms; and finally, proposing a new sequential coupling algorithm in multiscale simulations for comprehensive multi-field coupling calculations. The primary outcomes of this study demonstrate that asphalt concrete (AC)-graded pavements are susceptible to “down-top” cracks under hydro-mechanical loading, while open graded friction course (OGFC)-graded pavements have the potential to develop both “top-down” and “down-top” cracks. In AC-graded pavements, increasing the hydraulic head reduces stress concentrations, while in OGFC-graded pavements, changes in the permeability coefficient have a lesser impact on mechanical response. At the mesoscopic level, tensile stress concentrations in the asphalt mortar decrease significantly at higher temperatures. Furthermore, the OGFC-graded RVE model exhibits higher tensile stresses in the asphalt mortar compared to the AC-graded RVE model.

Ultrathin flaky FeSiAl and Fe3O4@C core-shell integrating the high-performance microwave absorber with gradient anti-corrosion barriers

Heterogeneous interface engineering and magnetic coupling are the main promising strategies for efficient microwave absorbers, but getting them stable in high-salt and humidity environments remains a challenge. Herein, we developed ultrathin flaky FeSiAl(FSA) integrating with Fe3O4@C core-shell for the high-performance microwave absorber with gradient anti-corrosion barriers. The Fe-Prussian blue analogue (PBA) derived microcubes decorated ultrathin FSA are prepared and transformed into Fe3O4@C core-shell in range of 500 ∼ 700 °C. The introduction of ferric oxide favors to impedance matching. Furthermore, the ultra-thin carbon layer and ferric oxide form a hybrid structure, which is conducive to enhancing electron spin and thereby enhancing microwave loss. This hybrid possess enhanced microwave absorption properties with a minimum reflection loss (RLmin) of −45.5 dB at 9.2 GHz at a thickness of 2.5 mm. Moreover, the maximum effective absorption bandwidth value reaches 5.2 GHz from 12.8 to 18 GHz at 1.6 mm. The gradient carbon layers and Fe3O4 provided the bi-barriers towards corrosive medium. Then corrosion resistance of the electric circuit increased up to 3.56×107 Ω∙cm2 for FSA/Fe3O4@C-600. Meanwhile, the corresponding corrosion current decreased into 2.52×10−8 A∙cm−2. Hence, introducing multi-heterointerfaces and dual-magnetic components opens up a fantastic avenue for designing high-efficient absorbers with gradient anti-corrosion barriers.

Heterogeneous network coupling induced ‘local sleep’ in brain cognitive networks

Heterogeneous network coupling induced ‘local sleep’ in brain cognitive networks

Carbon nanotubes-encapsulated Co/Co7Fe3 nanocomposites: Achieving wideband electromagnetic wave absorption at ultrathin-thickness by regulating magnetic phase ratio

Nowadays, through various strategies such as composition regulation and structural design, the electromagnetic wave (EMW) attenuation ability of composites has been significantly improved. Nevertheless, at ultra-thin sample matching thicknesses, it is still a challenge for absorbing materials to possess high-intensity and wide bandwidth simultaneously. In this work, the cobalt/iron nitrilotriacetic acid chelates (Co/Fe-NAC) were fabricated by a one-step hydrothermal self-assembly strategy. Then, a series of carbon nanotubes-encapsulated Co/Co7Fe3 (Co/Co7Fe3@CNTs) nanocomposites were constructed by coating glucose hydrothermal carbon on Co/Fe-NAC precursors and subsequent calcination process. By controlling the Co/Fe ion content, the magnetic phase ratio in the product can be efficiently regulated to comprehensively optimize microwave absorption (MA) performance. The minimum reflection loss (RL) of the optimized sample is −42.6 dB at only 1.1 mm thickness, and the effective absorption bandwidth (EAB) reaches up to 10.1 GHz (7.9–18 GHz). Surprisingly, for all samples, the widest EAB can exceed 8.2 GHz at the ultra-thin thickness (thinner than 1.3 mm) and the strongest RL values are all below −30 dB (99.9 % EMW can be absorbed). Such excellent MA performance is attributed to the strong magnetic loss of highly dispersed magnetic nanoparticles, the strong dielectric properties of carbon nanotubes and shells, optimized impedance matching, as well as the synergistic effect of multi-dimensional heterogeneous components and structures. Moreover, the high-frequency structure simulator (HFSS) was used to further analyze the multi-polarization behaviors and heterogeneous magnetic coupling effect. This work may provide a new direction to the fabrication of efficient and ultra-thin absorbers, and Co/Co7Fe3@CNTs nanocomposites may become a promising candidate for practical application in the MA field.

Recyclable Palladium-Catalyzed Carbonylative Coupling of Aryl Halides and Organoaluminum Compounds with tert-Butyl Iso­cyanide as CO Equivalent Leading to 1,2-Diketones

AbstractAn efficient heterogeneous palladium-catalyzed carbonylative coupling of aryl halides and organoaluminum compounds has been developed using tert-butyl isocyanide as CO equivalent. The carbonylation reaction proceeds smoothly in toluene with KOtBu as a base at 100 °C by using 10 mol% of an SBA-15-anchored bidentate phosphine palladium(0) complex [2P-SBA-15-Pd(0)] as the catalyst and provides a general and practical approach for the assembly of 1,2-diketones in good to excellent yields. This heterogenized palladium catalyst can be readily separated and recovered via a simple centrifugation process and reused for more than seven cycles with almost consistent catalytic efficiency.

Heterogeneous coupling of δ13Corg and δ13Ccarb during the Shuram Excursion: Implications for a large dissolved organic carbon reservoir in the Ediacaran ocean

The Ediacaran ocean recorded the largest negative carbonate carbon isotope (δ13Ccarb) excursion in Earth's history, the Shuram Excursion (SE). The relatively invariant character of organic carbon isotope (δ13Corg) profiles during the SE has been attributed to buffering by a large dissolved organic carbon (DOC) reservoir in the ocean. However, recent studies suggest that the DOC buffering may have been highly heterogeneous, a hypothesis that can be tested by assessing variability in the spatial and temporal ranges of δ13Corg buffering during the SE. In this study, we evaluated δ13Corg and δ13Ccarb records from multiple regions globally to test the heterogeneous buffering hypothesis. Making use of a high-precision astrochronological framework, we found that the buffering effect of DOC persisted for ∼2.7 Myr in Oman, ∼4.9 Myr in South China, and ∼5.9 Myr in Australia, demonstrating its temporal heterogeneity. Heterogeneous buffering is also demonstrated at a small spatial scale for South China sections based on a correlation framework subdividing the SE into three intervals: EN3a (δ13Ccarb decline from baseline to nadir), EN3b (δ13Ccarb stabilized at nadir), and EN3c (δ13Ccarb recovery from nadir value). The duration of δ13Corg buffering increased with water depth from shallow neritic to deep pelagic areas. The buffering effect terminated within EN3a in inner-shelf areas, within EN3b in an intra-shelf basin, and within EN3c in slope areas. Spatial variation in the offset between δ13Ccarb and δ13Corg values (Δ13C(carb-org)) is consistent with multiple sources of sedimentary organic matter. An average of ∼26 ‰ in inner-shelf areas implies mainly fresh phytoplankton debris, whereas an average of ∼18 ‰ in slope areas is consistent with dominance of DOC, which is thought to have been present in abundance in deeper anoxic watermasses. Thus, our study supports a large DOC reservoir in the late Ediacaran ocean that led to heterogeneous buffering during the SE at both basinal and global scales. Large shallow-to-deep oceanic δ13Ccarb and δ13Corg gradients of similar magnitude existed both before and during the SE, indicating that the circulation and productivity dynamics of the Ediacaran ocean were not significantly changed by the SE. The downward expansion of oxidant-rich surface watermasses during the SE improved the ventilation of shelf oceans while leaving the deep ocean anoxic, setting the stage for rapid biological evolution on continental shelves during the Cambrian Explosion.

Dual electron microregion with oxygen vacancy of Fe0.8La/MCM-48 in bridging peracetic acid and ozonation: Taking the pathway of free radical or nonradical generation?

Efficient tetracycline hydrochloride (TCH) degradation and interface reaction mechanism were investigated by constructing nonradical pathways in heterogeneous peracetic acid coupling with ozonation (O3/PAA) process. Ball-milling assisted Fe–La anchoring MCM-48 catalysts with dual electron microregion was designed to trigger 1O2-dominated non-radical for strong immunity to environment interference. Results exhibited that 83.4% degradation efficiency of TCH was achieved by Fe0.8La/MCM-48/O3/PAA system in only 2 min and 94% TCH was degraded in a 12-hour continuous flow experiment. La with oxygen vacancy regulated the local atomic environment and electron structure of Fe sites, which could initiate peracetic acid activation to promote 1O2 production by surface adsorbed atomic oxygen (*Oad) reaction and this process overcame a lower reaction energy barrier than the binding of surface *Oad to O3. This work offers a reasonable interpretation for Fe–La synergy for inducing non-free radical route, which furnishes theoretical support and practical application for heterogeneous O3/PAA.

Coupled analysis and simulation of safety risk in subway tunnel construction by shallow-buried excavation method based on system dynamics

To address the existing shortcomings in the research on the coupling of safety risk factors in subway tunnel construction using the shallow-buried excavation method, this paper conducts a coupled analysis and dynamic simulation of the safety risks associated with this construction method. Firstly, by analyzing the mechanisms and effects of risk coupling in shallow-buried excavation construction of subway tunnels, this study divides the risk system into four risk subsystems (human, material, management, and environment), establishes an evaluation index system for the coupling of safety risks, calculates the comprehensive weight values of the risk indicators using the AHP-entropy weight method, and constructs a risk coupling degree model by combining the inverse cloud model and efficacy function. Subsequently, based on the principles of system dynamics, a causal relationship diagram and a system dynamics simulation model for the coupling of “human-material” risks in construction are established using Vensim PLE software. Finally, the case study of the underground excavation section of Chengdu Metro Line 2 is employed to perform dynamic simulation using the established model. By adjusting the relevant risk coupling coefficients and simulation duration, the impact of the coupling of various risk factors on the safety risk level of the human-material coupling system is observed. The simulation results demonstrate that: 1) Heterogeneous coupling of human and material risks has a particularly significant effect on the system’s safety risks; 2) Violations by personnel and initial support structure defects are key risk coupling factors. The findings of this study provide new insights for decision-makers to assess the safety risk of shallow-buried excavation construction in subway tunnel.

A Hybrid Routing Pattern in Human Brain Structural Network Revealed By Evolutionary Computation.

The human brain functional connectivity network (FCN) is constrained and shaped by the communication processes in the structural connectivity network (SCN). The underlying communication mechanism thus becomes a critical issue for understanding the formation and organization of the FCN. A number of communication models supported by different routing strategies have been proposed, with shortest path (SP), random diffusion (DIF), and spatial navigation (NAV) as the most typical, respectively requiring network global knowledge, local knowledge, and both for path seeking. Yet these models all assumed every brain region to use one routing strategy uniformly, ignoring convergent evidence that supports the regional heterogeneity in both terms of biological substrates and functional roles. In this regard, the current study developed a hybrid communication model that allowed each brain region to choose a routing strategy from SP, DIF, and NAV independently. A genetic algorithm was designed to uncover the underlying region-wise hybrid routing strategy (namely HYB). The HYB was found to outperform the three typical routing strategies in predicting FCN and facilitating robust communication. Analyses on HYB further revealed that brain regions in lower-order functional modules inclined to route signals using global knowledge, while those in higher-order functional modules preferred DIF that requires only local knowledge. Compared to regions that used global knowledge for routing, regions using DIF had denser structural connections, participated in more functional modules, but played a less dominant role within modules. Together, our findings further evidenced that hybrid routing underpins efficient SCN communication and locally heterogeneous structure-function coupling.

Rapid degradation of high-concentration antibiotic via heterogeneous photocatalysis coupling Fenton-like oxidation with MIL-53(Fe) under visible light irradiation

The photocatalytic technology based on Metal-Organic Frameworks (MOFs) has shown promising applications in the field of antibiotic pollution control. However, it still faces challenges in efficiently removing high-concentration antibiotic wastewater. A typical Fe-containing MOF, MIL-53(Fe), was successfully synthesized and demonstrated efficient photocatalytic activity under visible light irradiation for high-concentrations of tetracycline hydrochloride (TCH). However, the bare MIL-53(Fe) exhibited unsatisfactory photocatalytic performance. To overcome the low degradation efficiency resulting from the rapid recombination of light-induced electron-hole pairs, H2O2 was introduced as an external electron acceptor to establish a synergistic Fenton-like system to couple with the photocatalysis process. The results showed that in the MIL-53(Fe)/H2O2/Vis system, 99% of 1 g/L TCH was degraded within 80 min, while the degradation efficiency of the MIL-53(Fe)/Vis process was only 4.89% under identical conditions. The degradation mechanism of the coupling system was performed by radical scavenging experiments and Electron Spin Resonance characterization. The results indicated that ·OH was the dominant radical in the coupled reaction, and ·O2- and h+ also played a role in this system. The significant improvement in TCH degradation efficiency during the coupling process was attributed to the following three factors: (1) In the coupling reaction process, photo-generated electrons can stimulate H2O2 to form ·OH radicals, inhibiting the recombination of photo-generated electrons and holes, improving the efficiency of the photocatalytic reaction. (2) FeIII in MIL-53(Fe) can be excited by photo-generated electrons and converted to FeII, which then stimulates H2O2 to form ·OH radicals. (3) FeIII in MIL-53(Fe) can convert with FeII, stimulate H2O2 to form ·OH radicals, and participate in the degradation reaction. In addition, the reusability and stability of the MIL-53(Fe) photocatalyst in the coupled system, as well as the impact of operational parameters, were systematically studied. This work demonstrates a feasible strategy for environmental remediation by enhancing the efficiency of MIL-53(Fe) in photocatalytic Fenton-like systems, thereby providing a viable approach for the treatment of high-concentration antibiotic wastewater.

Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra

Geometry and frictional states of the megathrust in subduction zones play critical roles on the rupture extent, hence the magnitude, of great earthquakes. However, their details are often difficult to obtain, primarily due to limited offshore geophysical observations. Here we overcome this challenge by precisely determining source parameters (i.e., location and focal mechanism) of medium-sized earthquakes using global broadband seismic waveform data. The dip angles of 108 Mw 5.0+ plate interface events from 1990 to 2017 in the central Sumatran subduction zone are tightly constrained by waveform inversion, and their locations are refined with surface-wave relocation and depth phases modeling. Our results reveal compact trench parallel earthquake belts at the up-dip and down-dip boundaries of the ruptures of the Mentawai 2007 Mw 8.4 and Mw 7.9 earthquakes. The down-dip seismicity belt marks ∼8º bending of the plate interface, suggesting that the change of fault geometry may have played a role in halting the megathrust rupture along with thermal effects. The up-dip seismicity belt shows a clear spatial complementarity to the largest events’ slip distribution. This belt is quite narrow (∼20 km) for the Mw 8.4 rupture but much broader (∼50 km) for the Mw 7.9 event. The combination of the up-dip seismicity belt and slip distributions matches well with the positive residual bathymetry and gravity anomalies, suggesting that these events resulted from long-term coupling on the plate boundary. Our findings suggest the importance of considering both up-dip and down-dip seismicity belts, along with residual bathymetry and gravity data, in understanding megathrust rupture behaviors and assessing the associated hazards.

LVI-Fusion: A Robust Lidar-Visual-Inertial SLAM Scheme

With the development of simultaneous positioning and mapping technology in the field of automatic driving, the current simultaneous localization and mapping scheme is no longer limited to a single sensor and is developing in the direction of multi-sensor fusion to enhance the robustness and accuracy. In this study, a localization and mapping scheme named LVI-fusion based on multi-sensor fusion of camera, lidar and IMU is proposed. Different sensors have different data acquisition frequencies. To solve the problem of time inconsistency in heterogeneous sensor data tight coupling, the time alignment module is used to align the time stamp between the lidar, camera and IMU. The image segmentation algorithm is used to segment the dynamic target of the image and extract the static key points. At the same time, the optical flow tracking based on the static key points are carried out and a robust feature point depth recovery model is proposed to realize the robust estimation of feature point depth. Finally, lidar constraint factor, IMU pre-integral constraint factor and visual constraint factor together construct the error equation that is processed with a sliding window-based optimization module. Experimental results show that the proposed algorithm has competitive accuracy and robustness.

Solvable dynamics of the three-dimensional Kuramoto model with frequency-weighted coupling.

The presence of coupling heterogeneity is deemed to be a natural attribute in realistic systems comprised of many interacting agents. In this work, we study dynamics of the 3D Kuramoto model with heterogeneous couplings, where the strength of coupling for each agent is weighted by its intrinsic rotation frequency. The critical coupling strength for the instability of incoherence is rigorously derived to be zero by carrying out a linear stability analysis of an incoherent state. For positive values of the coupling strength, at which the incoherence turns out to be unstable, a self-consistency approach is developed to theoretically predict the degree of global coherence of the model. Our theoretical analyses match well with numerical simulations, which helps us to deepen the understanding of collective behaviors spontaneously emerged in heterogeneously coupled high-dimensional dynamical networks.

The vegetation–topography heterogeneity coupling in the Loess Plateau, China

As a result of adaptation to the environment, the great environmental spatial heterogeneity leads to the high spatial heterogeneity of vegetation status. This coupling may be more apparent in water-limited drylands, where topography is the main determinant of small-scale variation in water availability and energy. Metrics describing this coupling may contribute to the detection of the extension of vegetation reshaped by human intervention and other driven forces. In this study, the heterogeneity index of coupling (HIC) was developed to indicate the coupling between spatial heterogeneity of vegetation status (Hv) and the spatial heterogeneity of topography (HT) in the Loess Plateau in northern China. The 16-day composed MODIS normalized vegetation index (NDVI) with a resolution of 250 m and SRTM DEM were employed to quantify the heterogeneity of vegetation status and the topographical heterogeneity. The results show that HIC varies among geomorphic zones, land cover types, and land cover change categories. Among all land cover types, HIC of sandy areas was the largest, followed by the HIC of the forest, shrub, farmland, and grassland. Among geomorphic zones, the highest HIC value appeared in plains with dense residential areas, followed by sandy land that is frequently reshaped by wind, rocky mountainous areas, hilly and gully loess plateaus, and loess tableland. It was revealed that the alternation of vegetation by human activities and natural disturbances shaped greater HIC. Results of this study approved the effectiveness of the HIC in reflecting the coupling of the vegetation status with topography at regional scale.

A Sum-of-States Preservation Framework for Open Multiagent Systems With Nonlinear Heterogeneous Coupling

A Sum-of-States Preservation Framework for Open Multiagent Systems With Nonlinear Heterogeneous Coupling

Stochastic simulation methods in the study of cell rhythm

Stochastic simulation methods play a crucial role in the study of cellular rhythms. Based on the characteristics of stochastic algorithms, we can more accurately capture the noise effects existing in biological systems and explore their impact on cell rhythms. The findings from stochastic simulation methods shed light on how cell rhythms operate at the molecular level, and this paper presents them inductively for different algorithm types, enabling a deeper understanding of their characteristics. Furthermore, based on the analysis of existing studies, this paper finds that a stochastic simulation approach that considers spatial heterogeneity and intercellular coupling helps reveal the design principles and functional characteristics of the cellular rhythmic system. However, existing stochastic methods also have limitations, including the arbitrariness of parameters and ignoring spatial features. This paper argues that future improvements should focus on integrating quantitative data, accounting for spatial effects, and increasing computational efficiency. These enhancements will contribute to a comprehensive understanding of the generation of cellular rhythms and their importance in biological processes.

Coupling resonance of signal responses induced by heterogeneously mixed positive and negative couplings in cognitive subnetworks

How weak external signals are detected in cognitive subnetworks is one of the key problems to understand how brain functions work. So far, most studies on signal responses are focused on artificial complex networks and it is found that a topological resonance can be induced by the feature of scale-free networks, but little attention has been paid to real brain networks, especially the cognitive subnetworks responsible for signal responses. Herein we address this problem in real brain networks but do not find such a topological resonance, indicating that scale-free is not the key feature of brain networks. Surprisingly, we find a novel resonance effect of signal response induced by heterogeneously mixed positive and negative couplings and thus name it as coupling resonance of signal responses, which explains the mechanism of how brain networks, especially the cognitive subnetworks, detects weak signals. We investigate this coupling resonance in the cases of both heterogeneous couplings and heterogeneous oscillators and find that there is an optimal phenomenon on both the average and standard deviation of coupling strengths. Further, we confirm this coupling resonance in real cognitive subnetworks with weighted links. Finally, we provide a theoretical analysis to show that this coupling resonant comes from the coexistence of the two different local states of neighboring nodes.