Slow Propagation Research Articles

A review of chemical kinetic mechanisms and after-treatment of amino fuel combustion.

Ammonia is a highly promising carbon-neutral fuel. The use of ammonia as a fuel for internal combustion engines can reduce fossil energy consumption and greenhouse gas emissions. However, the high ignition energy required for ammonia and the slow flame propagation rate result in low combustion efficiency when ammonia is used directly in internal combustion engines. The combination of ammonia with highly reactive fuels improves combustion quality and increases efficiency. However, the combustion of these combined fuels generates particulate matter, CO, hydrocarbon, and significant amounts of NOx. Therefore, pollutant emissions must be reduced through after-treatment technologies. In this paper, a series of combustion and post-treatment challenges faced by amino fuel combustion in internal combustion engines are extensively discussed and the combustion reaction mechanisms of different amino fuels are also analyzed. The paper then reviews five key technologies applicable to the reprocessing of amino fuels, including selective catalytic reduction, selective catalytic reduction filter technology, electrochemical methods for NOx removal, direct catalytic decomposition of N2O, and ammonia sliding catalysts. An in-depth discussion of the catalytic materials and reaction mechanisms involved in these technologies is also provided in this paper. Finally, the paper summarizes the main technical challenges that must be addressed for the future application of amino fuels in internal combustion engines. These discussions can serve as an essential reference for developing and applying critical technologies for combustion control and pollutant treatment of amino fuels.

Delayed Tooth Development and the Impaired Differentiation of Stem/Progenitor Cells in Incisors from Type 2 Diabetes Mice.

Patients with diabetes mellitus (DM) have an increased risk of tooth decay caused by alterations in their tooth development and their oral environment, as well as a tendency to present with pulp infection due to compromised immune response. The present study analyzed the characteristic alterations in tooth development under DM conditions using incisors from db/db type 2 diabetic mouse model (T2DM mice). In micro-CT analyses, T2DM mice showed delayed dentin and enamel formation. Through transcriptomic analyses, pre-ameloblast- and pre-odontoblast-specific genes were found to be significantly decreased in the incisors of T2DM mice, whereas major ameloblast- and mature odontoblast-specific genes were not changed. Stem cell markers were decreased in T2DM mice compared to those from the control mice, suggesting that the stemness of dental pulp cells (DPCs) is attenuated in T2DM mice. In vitro analyses demonstrated that DPCs from T2DM mice have lower colony-forming units (CFU), slower propagation, and diminished differentiation characteristics compared to the control. These data suggest that T2DM conditions could impair the differentiation property of multiple progenitor/stem cells in the tooth, resulting in delayed tooth development in T2DM mice.

Improving Visible Light Photocatalysis Using Optical Defects in CoOx-TiO2 Photonic Crystals.

The rational design of photonic crystal photocatalysts has attracted significant interest in order to improve their light harvesting and photocatalytic performances. In this work, an advanced approach to enhance slow light propagation and visible light photocatalysis is demonstrated for the first time by integrating a planar defect into CoOx-TiO2 inverse opals. Trilayer photonic crystal films were fabricated through the successive deposition of an inverse opal TiO2 underlayer, a thin titania interlayer, and a photonic top layer, whose visible light activation was implemented through surface modification with CoOx nanoscale complexes. Optical measurements showed the formation of "donor"-like localized states within the photonic band gap, which reduced the Bragg reflection and expanded the slow photon spectral range. The optimization of CoOx loading and photonic band gap tuning resulted in a markedly improved photocatalytic performance for salicylic acid degradation and photocurrent generation compared to the additive effects of the constituent monolayers, indicative of light localization in the defect layer. The electrochemical impedance results showed reduced recombination kinetics, corroborating that the introduction of an optical defect into inverse opal photocatalysts provides a versatile and effective strategy for boosting the photonic amplification effects in visible light photocatalysis by evading the constraints imposed by narrow slow photon spectral regions.

Slow Propagation Velocities in Schrödinger Operators with Large Periodic Potential

Slow Propagation Velocities in Schrödinger Operators with Large Periodic Potential

Process-Based Evaluation of Intraseasonal Oceanic Kelvin Waves in the Pacific Ocean in CMIP6 Models

Abstract Oceanic intraseasonal Kelvin waves (KWs) help modulate upper-ocean thermal characteristics, providing feedbacks to important coupled air–sea phenomena in the tropics. The recent availability of daily thermocline depth fields from several phase 6 of the Coupled Model Intercomparison Project (CMIP6) models makes it possible to evaluate the performance of KWs and identify potential sources of bias. Most models fail to simulate a realistic spatial distribution of KW variability. Models simulate a large variability of KWs in the western or eastern Pacific rather than in the central Pacific as observed. The modeled KWs propagate slowly (about 1.5 m s−1) compared to observations (about 2.5 m s−1). This slow propagation is also identified in wavenumber–frequency spectra for KWs and meridional KW structures, which is more consistent with a second baroclinic mode structure in models compared to the first baroclinic mode structure in observations. An analysis of the relative contributions of the vertical wavenumber and background ocean stability to KW phase speeds indicates that the high vertical wavenumber bias in models contributes most to the slow propagation, in which the higher-than-observed vertical wavenumbers imply the biased incorporation of higher baroclinic modes in the model KW structure. This finding is further supported by the results of vertical mode decomposition that incorporates background density profiles. These results indicate that a realistic representation of the KW vertical structure is essential to produce realistic KW propagations in models. Significance Statement Oceanic intraseasonal Kelvin waves (KWs) play a significant role in regulating the heat content and temperature of the ocean, which provides feedbacks to coupled ocean–atmosphere phenomena in the tropics such as El Niño–Southern Oscillation (ENSO). Consequently, identifying the biases in KWs and the potential sources of those biases in state-of-the-art models is essential to improve simulations of ENSO and its diversity and advance forecasts of weather extremes around the globe induced by ENSO. We find that KWs in the models propagate slower than observations, mainly due to biases in their vertical structure, with secondary effects due to biases in model ocean stability. These issues may be potential sources for current imperfect ENSO model simulations and predictions.

Numerical investigation on the effect of ignition timing on a low-temperature hydrogen-fueled Wankel rotary engine with passive pre-chamber ignition

Adopting the low-temperature hydrogen evaporated from the liquid hydrogen is capable of improving volumetric efficiency for the Wankel rotary engine (WRE). Considering the difficulty in ignition and slow flame propagation of low-temperature hydrogen-air mixtures, the passive pre-chamber is used to improve ignition and combustion. A three-dimensional computational fluid dynamics model for a turbulent jet ignition (TJI) WRE fueled by low-temperature hydrogen was established. The effects of low temperature and TJI on the in-cylinder flow field, combustion, emissions and leakage in the TJI-WRE fueled by low-temperature hydrogen were studied under different ignition timings. The results indicated that low-temperature tends to suppress the flame propagation, whereas TJI can accelerate the flame speed and promote flame propagation to the unburned zone in the combustion chamber. Combining low-temperature hydrogen with the passive pre-chamber can achieve high engine thermal efficiency and power while significantly reducing leakage. With the ignition timing set at 18 °CA before the top dead center, the indicated thermal efficiency reached 39.49% and the indicated mean effective pressure peaked at 0.77 MPa. Compared to the original engine, fresh mixture leakage through spark plug cavities and adjacent chambers was reduced by 72.13% and 78.79%, respectively.

Multi-scale study on the crack resistance and energy dissipation mechanism of modified rubberized concrete

This study investigates the impact of rubber aggregates with different particle sizes, volume proportions, and pretreatment methods on the crack resistance and energy dissipation properties of rubberized concrete (RuC). The mechanisms of crack resistance and energy consumption are analyzed from macroscopic, mesoscopic, and microscopic perspectives using static and dynamic performance tests, digital image correlation (DIC), and scanning electron microscopy (SEM). These techniques reveal changes in crack patterns, interface transition zones, and pore characteristics. The findings demonstrate that rubber aggregates significantly slow crack propagation and enhance damping energy dissipation, with the volume content of rubber being the most critical factor. The inclusion of rubber aggregates introduces "cavity defects" into the concrete structure, which accounts for RuC's reduced strength compared to standard concrete while highlighting its advantages in vibration reduction and energy absorption. These insights are essential for advancing research on material modifications and microscopic numerical simulations, contributing to reduced carbon emissions.

Effects of water sprays on hydrogen autoignition in heated air

The effects of water mist with different diameters and mass loadings on hydrogen auto-ignition in air with elevated temperatures and pressures are studied. It is shown that smaller droplets with larger mass loading are the most effective in inhibiting the auto-ignition process. Under elevated initial pressures and temperatures, the role of water mist in impacting auto-ignition is minimal, primarily because the ignition delay is substantially shorter than the droplet evaporation duration. As the initial temperature decreases, there exists a temperature value below which water mist markedly extends the ignition delay time, even escalating it by up to two orders of magnitude or causing a complete suppression of ignition. The rate of production for important radicals was analyzed. The data indicates that the evaporation of the water mist lowers the initial temperature, leading to a reduction in the rate of the temperature-sensitive fast chain branching reaction. In contrast, the third body reaction that generates HO2 is not sensitive to temperature. Meanwhile, the introduction of H2O results in an earlier activation of the third body reactions. Consequently, the production of HO2 is enhanced, emphasizing the role of subsequent slow chain propagation reactions that generate OH, thereby extending the ignition delay. By deactivating the mass transfer between two phases and introducing artificial species, it is evident that water vapor dilution and thermal effects predominantly influence the ignition delay, while its role as a direct reactant is minimal.

Combustion characteristics of ammonia-hydrogen mixture with turbulent jet ignition

Ammonia and hydrogen are promising zero-carbon fuels that can help combustion engines achieve the zero-carbon emissions target. However, ammonia features high ignition energy demand and slow flame propagation speed. Pre-chamber turbulent jet ignition, with high ignition energy and enhanced in-cylinder turbulence, shows potential for achieving efficient and stable engine combustion with low-reactivity fuels. The optical constant volume combustion chamber simulates the process of pressure environment in the engine cylinder during the compression stroke to push the unburned gas into the pre-chamber, and simulates the process of jet ignition during the pressure environment in the main combustion chamber at the end of the compression stroke. The effects of different parameters such as ambient pressure, hydrogen fraction, and orifice diameter on the turbulent jet ignition combustion were investigated. The results indicate that jet ignition is a more effective means than spark ignition to accelerate the ammonia-hydrogen mixture combustion. A hot jet carrying heat and active radicals is injected into the main chamber due to the pressure difference, and then ignites the ammonia-hydrogen mixture. With increased hydrogen volume fraction, the ignition process is advanced due to the earlier formation and higher reactivity of the hot jet. Meanwhile, the enhanced fuel reactivity and turbulent disturbance accelerate turbulent flame propagation with increased hydrogen addition. The ignition delay time and jet flame axial development are accelerated with increase in equivalence ratio from 0.6 to 1.0. With increased orifice diameter, the pre-chamber jet flame is observed due to the weakened quenching effect, leading to shortened ignition delay and extended combustion duration.

A Workflow for Creating Gastric Computational Models from SPARC Scaffolds

In-silico studies are an ideal medium to model and improve our understanding of the mechanisms underlying gastric motility in health and disease. In this study, a workflow to create computational models of the stomach was developed using SPARC scaffolds. Three anatomically based finite element method (FEM) models of the rat stomach incorporating experimental measurements of muscle layer thickness and fiber orientations across the stomach were developed: (i) 2D (surface) FEM model with no thickness, (ii) 3D (volume) FEM model with a fixed thickness across the longitudinal and circular muscle layers, and (iii) 3D (volume) FEM model with varying thickness across the longitudinal and circular muscle layers. The three FEM models were subsequently used in whole-organ slow wave simulations and the impact of anatomical details on the simulation outcomes was investigated. The 3D FEM model with varying thickness was the most computationally expensive, while the 2D FEM model provided the fastest solution (a 200 s simulation took 8 min vs. 38 h to solve). The spatiotemporal profiles of the slow wave activation and propagation in the three FEM models were in good agreement. The largest temporal difference of 1 s in cellular activation was observed between the 2D FEM model and the varying thickness 3D FEM model in the most distal-stomach regions. These FEM models and developed workflow will be used in in-silico studies to improve our understanding of the structure-function relationship in the stomach and identify the optimal parameters of electrical therapies, an alternative treatment for the motility disorders in the stomach. In addition, the developed workflow can be readily used to generate computational models of other organs using SPARC scaffolds.

Combining Imaging and Electrophysiology to Visualize and Record Spreading Depolarizations in Mice.

Spreading Depolarizations (SDs) are massive events in the brain that often go undetected due to their slow propagation through gray matter. Because SD detection can be elusive, it is optimally confirmed using multiple methods. This protocol describes methods for combining imaging and electrophysiology to detect SDs in a manner that most laboratories can reliably and easily adopt. SDs occur following traumatic brain injuries, stroke, subarachnoid hemorrhages, ischemia, and migraine aura. Historically, SDs have been recorded using DC amplifiers, which can resolve the slow extracellular shift and the depression in high-frequency activity. However, DC amplifiers are nearly impossible to use for chronic in vivo recordings. This protocol employs a common AC amplifier for in vivo electrophysiology recordings to confirm high-frequency depression, along with non-invasive imaging necessary to detect the propagating wave of SD. These methods can be reliably adopted and/or modified for most experimental approaches to confirm the presence or absence of SDs following brain injury.

Explaining slow seizure propagation with white matter tractography.

Epileptic seizures recorded with stereo-EEG can take a fraction of a second or several seconds to propagate from one region to another. What explains such propagation patterns? We combine tractography and stereo-EEG to determine the relationship between seizure propagation and the white matter architecture and to describe seizure propagation mechanisms. Patient-specific spatiotemporal seizure propagation maps were combined with tractography from diffusion imaging of matched subjects from the Human Connectome Project. The onset of seizure activity was marked on a channel-by-channel basis by two board-certified neurologists for all channels involved in the seizure. We measured the tract connectivity (number of tracts) between regions-of-interest pairs among the seizure onset zone, regions of seizure spread and non-involved regions. We also investigated how tract-connected the seizure onset zone is to regions of early seizure spread compared with regions of late spread. Comparisons were made after correcting for differences in distance. Sixty-nine seizures were marked across 26 patients with drug-resistant epilepsy; 11 were seizure free after surgery (Engel IA) and 15 were not (Engel IB-Engel IV). The seizure onset zone was more tract-connected to regions of seizure spread than to non-involved regions (P < 0.0001); however, regions of seizure spread were not differentially tract-connected to other regions of seizure spread compared with non-involved regions. In seizure-free patients only, regions of seizure spread were more tract-connected to the seizure onset zone than to other regions of spread (P < 0.0001). Over the temporal evolution of a seizure, the seizure onset zone was significantly more tract-connected to regions of early spread compared with regions of late spread in seizure-free patients only (P < 0.0001). By integrating information on structure, we demonstrate that seizure propagation is likely to be mediated by white matter tracts. The pattern of connectivity between seizure onset zone, regions of spread and non-involved regions demonstrates that the onset zone might be largely responsible for seizures propagating throughout the brain, rather than seizures propagating to intermediate points, from which further propagation takes place. Our findings also suggest that seizure propagation over seconds might be the result of a continuous bombardment of action potentials from the seizure onset zone to regions of spread. In non-seizure-free patients, the paucity of tracts from the presumed seizure onset zone to regions of spread suggests that the onset zone was missed. Fully understanding the structure-propagation relationship might eventually provide insight into selecting the correct targets for epilepsy surgery.

Numerical simulation of mechanical properties and damage process of carbon nanotube concrete under triaxial compression and splitting conditions

To investigate the mechanical properties and failure processes of carbon nanotube concrete, a three-dimensional meso-scale finite element model of concrete was constructed. Using ABAQUS software, numerical simulations were conducted on concrete samples with different carbon nanotube concentrations under triaxial compression and splitting conditions. The results indicate that under splitting conditions, the failure of the specimens initially occurs along the loading direction from both ends, with few cracks and slow propagation. Subsequently, the cracks rapidly expand, penetrating the entire specimen, leading to the formation of a macro-fracture surface with a crack aligned with the loading direction. This failure mode manifests as a straight crack. At the same loading rate, the tensile strength of the specimens with different carbon nanotube concentrations increases to varying degrees during splitting failure, with a maximum increase of 45.10% to 4.15 MPa. nder triaxial compression conditions, the main failure mode of the specimens exhibits shear failure characteristics. As the confining pressure gradually increases, the failure angle of the specimens enlarges. Under low confining pressure, there are fewer wing-shaped tensile cracks at the shear failure surface of the specimens. As the confining pressure increases, irregular shear failures and multiple shear planes appear in the specimens, resulting in more complex failure modes. For specimens with the same carbon nanotube concentration, the triaxial compressive strength of carbon nanotube concrete specimens increases with increasing confining pressure. The triaxial compressive strengths of the specimens under confining pressures of 5 MPa, 10 MPa, 15 MPa, and 20 MPa are 90.48 MPa, 122.72 MPa, 137.22 MPa, and 172.65 MPa, with strength increases of 35.63%, 51.66%, and 90.81%, respectively.

Azimuthally Modulating Surface Plasmon Polaritons

Abstract We suggest a scheme for the lossless excitation of surface plasmon polaritons (SPPs) at a metal-dielectric interface using a Laguerre Gaussian (LG) beam. We consider a three-layer structure consisting of a top transparent medium, a middle metal thin film, and a dielectric bottom layer. The dielectric medium contains three-level atoms exhibiting electromagnetically induced transparency (EIT). By applying a control field, a LG beam, and a microwave field, we induce azimuthally varying permittivity, which leads to the azimuthal modulation of SPPs. The propagation length of SPPs is increased when excited by a LG beam carrying optical angular momentum (OAM). Moreover, the group velocity of SPPs can be effectively controlled by adjusting the OAM and azimuthal angle of the LG beam, allowing for both slow and fast propagation of SPPs.

Mouse polyomavirus infection induces lamin reorganisation.

The nuclear lamina is a dense network of intermediate filaments beneath the inner nuclear membrane. Composed of A-type lamins (lamin A/C) and B-type lamins (lamins B1 and B2), the nuclear lamina provides a scaffold for the nuclear envelope and chromatin, thereby maintaining the structural integrity of the nucleus. A-type lamins are also found inside the nucleus where they interact with chromatin and participate in gene regulation. Viruses replicating in the cell nucleus have to overcome the nuclear envelope during the initial phase of infection and during the nuclear egress of viral progeny. Here, we focused on the role of lamins in the replication cycle of a dsDNA virus, mouse polyomavirus. We detected accumulation of the major capsid protein VP1 at the nuclear periphery, defects in nuclear lamina staining and different lamin A/C phosphorylation patterns in the late phase of mouse polyomavirus infection, but the nuclear envelope remained intact. An absence of lamin A/C did not affect the formation of replication complexes but did slow virus propagation. Based on our findings, we propose that the nuclear lamina is a scaffold for replication complex formation and that lamin A/C has a crucial role in the early phases of infection with mouse polyomavirus.

Generation of second-order sidebands and slow–fast light in cavity magnomechanics with a parametric amplifier

In this work, we theoretically investigate the optical second-order sideband (OSS) efficiency and group delay of an output probe field in a two-coupled cavity magnomechanics (CMM) system. The setup comprises a gain (active) cavity and a passive (loss) cavity, which simultaneously includes an optical parametric amplifier (OPA) and a yttrium iron garnet sphere to facilitate magnon–photon coupling. Employing experimentally attainable parameters, we show that the presence of an OPA can significantly enhance the optical transmission rate and OSS efficiency. We show that photon–magnon strong coupling can enhance OSS efficiency substantially when compared to weak photon–magnon coupling. Our results, in particular, show that the OSS’s efficiency may be significantly improved for active–passive-coupled cavities as compared to the passive–passive cavities system. Furthermore, we demonstrate that modifying the system configurations may change the group delay, affecting the transition from rapid to slow light propagation, and vice versa. Our results provide a novel and easy approach to designing CMM devices for altering light propagation, with possible applications including optical switching, information storage, and accurate measurement of weak signals.

Simultaneous optical imaging of gastric slow waves and contractions in the in vivo porcine stomach.

Gastric peristalsis is governed by electrical "slow waves" generally assumed to travel from proximal to distal stomach (antegrade propagation) in symmetric rings. Although alternative slow-wave patterns have been correlated with gastric disorders, their mechanisms and how they alter contractions remain understudied. Optical electromechanical mapping, a developing field in cardiac electrophysiology, images electrical and mechanical physiology simultaneously. Here, we translate this technology to the in vivo porcine stomach. Stomachs were surgically exposed and a fluorescent dye (di-4-ANEQ(F)PTEA) that transduces the membrane potential (Vm) was injected through the right gastroepiploic artery. Fluorescence was excited by LEDs and imaged with one or two 256 × 256 pixel cameras. Motion artifact was corrected using a marker-based motion-tracking method and excitation ratiometry, which cancels common-mode artifact. Tracking marker displacement also enabled gastric deformation to be measured. We validated detection of electrical activation and Vm morphology against alternative nonoptical technologies. Nonantegrade slow waves and propagation direction differences between the anterior and posterior stomach were commonly present in our data. However, sham experiments suggest they were a feature of the animal preparation and not an artifact of optical mapping. In experiments to demonstrate the method's capabilities, we found that repolarization did not always follow at a fixed time behind activation "wavefronts," which could be a factor in dysrhythmia. Contraction strength and the latency between electrical activation and contraction differed between antegrade and nonantegrade propagation. In conclusion, optical electromechanical mapping, which simultaneously images electrical and mechanical activity, enables novel questions regarding normal and abnormal gastric physiology to be explored.NEW & NOTEWORTHY This article introduces a novel method for imaging gastric electrophysiology and mechanical function simultaneously in anesthetized, open-abdomen pigs. We demonstrate it by observing propagating slow-wave depolarization and repolarization along with the strength, spatial distribution, and direction of contractions. In addition, we observe that in this animal preparation, slow waves often do not propagate from the proximal to distal stomach and are frequently asymmetric between the anterior and posterior sides of the stomach.

Analysis on a five-spot well for enhancing energy recovery from silty natural gas hydrate deposits in the South China Sea

The five-spot well is a promising technique for enhancing the inherent low gas production rate from silty natural gas hydrate (NGH) reservoirs with low permeability in the South China Sea (SCS). However, the production characteristics and the responses to key geological and engineering factors are still unclear and warrants investigation. Herein, we first establish a three-dimensional reservoir model based on the SH2 NGH deposits at SCS with the implementation of a five-spot well. We systematically examine the gas production enhancement effect and the unexpected well-to-well interaction induced by long-term depressurization. A sensitivity analysis on the effects of bottomhole pressure (Pbtm), permeability (k) and hydrate saturation (SH) is conducted to elucidate the key factors controlling the gas production enhancement. Our results reveal that the five-spot well significantly improves the gas productivity with cumulative gas production increased to 4.12 times that of a single well over 10 years. The well interference on gas production is not significant in the early stage but becomes more significant as depressurization sustains. Due to the relatively slow pressure propagation at the inner well, contribution to gas production from the inner well decreases over time while the outer wells increase. Based on the sensitivity analysis, gas production increases with decreasing Pbtm, increasing k, and decreasing SH with Pbtm and k as the key controlling factors. The findings provide valuable design basis for the adoption of a multi-well system in enhancing gas production for targeted NGH reservoirs in the next field production trial at SCS.

Modelling of ICRH slow wave propagation and absorption in Wendelstein 7-X stellarator

Abstract The propagation and absorption of the slow waves in the three-ion plasma of the Wendelstein 7-X stellarator have been investigated by ray tracing. The aim of the study is to obtain a qualitative notion of the penetration into the plasma and absorption of the wave excited by the potential difference between the antenna conductors and the antenna box. It has been discovered that the rays propagate along the magnetic field lines over a significant distance, up to 6 m, from the antenna. They weakly, to a depth of 0.1 m, penetrate into the plasma. Absorption of the slow waves by electrons does not lead to the generation of the currents capable of affecting the plasma equilibrium. Most of the slow waves are absorbed beyond the region of ion-ion hybrid resonance in the zone of cyclotron resonance of He3 ions at the periphery of the plasma. The ICRH of the three-ion W 7-X plasma will be used to heat He3 ions to high energies and simulate the confinement of alpha particles in an optimized stellarator configuration. The presence of a source of hot He3 ions, which are poorly confined, at the periphery of the plasma can affect the experimental results.

Slow rupture in a fluid-rich fault zone initiated the 2024 Mw 7.5 Noto earthquake.

The 2024 moment magnitude 7.5 Noto Peninsula (Japan) earthquake caused devastation to communities and was generated by a complex rupture process. Using space geodetic and seismic observations, we have shown that the event deformed the peninsula with a peak uplift reaching 5 meters at the west coast. Shallow slip exceeded 10 meters on an offshore fault. Peak stress drop was greater than 10 megapascals. This devastating event began with a slow rupture propagation lasting 15 to 20 seconds near its hypocenter, where seismic swarms had surged since 2020 because of lower-crust fluid supply. The slow start was accompanied by intense high-frequency seismic radiation. These observations suggest a distinct coseismic slip mode reflecting high heterogeneity in fault properties within a fluid-rich fault zone.