Transmission Electron Microscopy Observations Research Articles

Unconventional Polarization Response in Titanite-Type Oxides due to Hashed Antiferroelectric Domains.

Domains in a crystal, which have crystallographic uniformity and are geometrically segmented, typically arise from various phase transitions. The physical properties within individual domains are inherently the same as those in the homogeneous bulk. As a result, sufficiently large domains have little influence on the bulk properties. However, as the domains decrease in size to the nanoscale, for instance, due to multiple phase instabilities or spatial inhomogeneities, then the materials often acquire exceptional functionalities that are unattainable without these domains. This effect is exemplified by the ultrahigh dielectric and piezoelectric responses observed in ferroelectric oxides with nanoscale polar domains as well as in ferroelectric relaxors with polar nanoclusters. Here, we demonstrate that hashed nanoscale domains in an antiferroelectric material are also capable of boosting dielectric permittivity in an unconventional way. This discovery has been made in an antiferroelectric titanite-type oxide, CaTi(Si1-xGex)O5, in which the permittivity significantly increases when the antiferroelectric order becomes short-range. Our transmission electron microscopy observations have clarified that polar regions simultaneously appear around antiphase boundaries in the antiferroelectric phase of CaTi(Si1-xGex)O5. As the concentration of the antiphase boundary increases, the polar regions become denser and play a crucial role in boosting the permittivity. At the composition of x = 0.5, the value of the permittivity finally reaches double that in the bulk and shows excellent linearity, at least until an electric field of 500 kV/cm is applied. The present findings highlight the promise of domain engineering for boosting the permittivity in antiferroelectrics as a way to develop materials with excellent dielectric properties.

Copper nanoparticle and point defect formation in Cu+-Na+ ion-exchanged glass using protons of 2 MeV energy.

There are several applications for irradiating materials with protons that could provide alternative methodologies to synthesize and induce the formation of new compounds of different size scales. In this study, we explored the effects of proton irradiation oncommercial glass silicate that was previously subjected to a Cu+-Na+ ion exchange (IE) treatment at 600 °C for a duration of 60 min. The ion-exchanged glass samples were irradiated with protons (p+) of 2 MeV energy at doses in the range of thousands of grays (3.3 × 103, 7.9 × 103 Gy) and hundreds of thousands of grays (3.6 × 105 Gy). Significant changes in the optical and structural properties were observed post the radiation treatment. The UV-Visible absorption spectra of the irradiated samples revealed the appearance of overlapping absorption bands, which could be deconvoluted into three Gaussian-shaped bands peaking at 566, 620 and 680 nm. These three bands could be attributed to the surface plasmon resonance (SPR) of copper nanoparticles, non-bridging oxygen hole centers (NBOHCs) and self-trapped hole (STH) defects, respectively. Prominent photoluminescence (PL) was observed in the Cu-exchanged and irradiated samples, mainly induced by the presence of both Cu+ and Cu2O. Increasing the irradiation dose led to an increase in the PL intensity due to the conversion of Cu2+ ions into Cu+. This result was confirmed by electron paramagnetic resonance (EPR) spectroscopy that shows a decrease in the Cu2+ signal when increasing the dose of proton exposure. Transmission electron microscopy (TEM) and high-resolution TEM (TEM and HRTEM) observations confirmed the presence of copper nanoparticles (CuNPs) in the doped and p+ irradiated Cu-exchanged glass silicate samples. These CuNPs were found to be crystalline with an average size of 12.39 nm.

Unraveling the Unique Strong Metal-Support Interaction in Titanium Dioxide Supported Platinum Clusters for the Hydrogen Evolution Reaction.

Strong metal-support interaction (SMSI) is crucial to modulating the nature of metal species, yet the SMSI behaviors of sub-nanometer metal clusters remain unknown due to the difficulties in constructing SMSI at cluster scale. Herein, we achieve the successful construction of the SMSI between Pt clusters and amorphous TiO2 nanosheets by vacuum annealing, which required a relatively low temperature that avoids the aggregation of small clusters. In situ scanning transmission electron microscopy observation is employed to explore the SMSI behaviors, and the results reveal the dynamic rearrangement of Pt atoms upon annealing for the first time. The originally disordered Pt atoms become ordered as the crystallizing of the amorphous TiO2 support, forming an epitaxial interface between Pt and TiO2. Such SMSI state can remain stable in oxidation environment even at 400 °C. Further investigations prove that the electron transfer from TiO2 to Pt occupies the Pt 5d orbitals, which is responsible for the disappeared CO adsorption ability of Pt/TiO2 after forming SMSI. This work not only opens a new avenue for constructing SMSI at cluster scale but also provides in-depth understanding on the unique SMSI behavior, which would stimulate the development of supported metal clusters for catalysis applications.

Uniting Ultrahigh Plasticity with Near‐Theoretical Strength in Submicron‐Scale Si via Surface Healing

AbstractAs a typical hard but brittle material, Si tends to fracture abruptly at a stress well below its theoretical strength, even if the tested volume goes down to submicron scale, at which materials are usually nearly free of flaws or extended defects. Here, via the thermal–oxidation–mediated healing of the surface that is the preferred site for cracks or dislocations initiation, the premature fracture can be effectively inhibited and the over 50% homogeneous plastic strain with the near‐theoretical strength (twice the value of the unhealed counterpart) are united in submicron‐sized Si particles. In situ transmission electron microscope observations and atomistic simulations elucidate the confinement effect from the passivated and smoothened thermal oxide, which retards the dislocation nucleation and transforms the dominant deformation mechanism from partial dislocation to the more mobile full dislocation. This work demonstrates an effective and feasible surface engineering pathway to optimize the mechanical properties of Si at small scales.

Strategy toward In-Cell Self-Assembly of an Artificial Viral Capsid from a Fluorescent Protein-Modified β-Annulus Peptide.

In-cell self-assembly of natural viral capsids is an event that can be visualized under transmission electron microscopy (TEM) observations. By mimicking the self-assembly of natural viral capsids, various artificial protein- and peptide-based nanocages were developed; however, few studies have reported the in-cell self-assembly of such nanocages. Our group developed a β-Annulus peptide that can form a nanocage called artificial viral capsid in vitro, but in-cell self-assembly of the capsid has not been achieved. Here, we designed an artificial viral capsid decorated with a fluorescent protein, StayGold, to visualize in-cell self-assembly. Fluorescence anisotropy measurements and fluorescence resonance energy transfer imaging, in addition to TEM observations of the cells and super-resolution microscopy, revealed that StayGold-conjugated β-Annulus peptides self-assembled into the StayGold-decorated artificial viral capsid in a cell. Using these techniques, we achieved the in-cell self-assembly of an artificial viral capsid.

Immunohistochemical and Morphometric Assessment on the Biological Function and Vascular Endothelial Cells in the Initial Process of Cortical Porosity in Mice With PTH Administration.

To clarify the cellular mechanism of cortical porosity induced by intermittent parathyroid hormone (PTH) administration, we examined the femoral cortical bone of mice that received 40 µg/kg/day (four times a day) human PTH (hPTH) (1-34). The PTH-driven cortical porosity initiated from the metaphyseal region and chronologically expanded toward the diaphysis. Alkaline phosphatase (ALP)-positive osteoblasts in the control mice covered the cortical surface, and endomucin-positive blood vessels were distant from these osteoblasts. In PTH-administered mice, endomucin-reactive blood vessels with TRAP-positive penetrated the ALP-positive osteoblast layer, invading the cortical bone. Statistically, the distance between endomucin-positive blood vessels and the cortical bone surface abated after PTH administration. Transmission electron microscopic observation demonstrated that vascular endothelial cells often pass through the flattened osteoblast layer and accompanied osteoclasts in the deep region of the cortical bone. The cell layers covering mature osteoblasts thickened with PTH administration and exhibited ALP, α-smooth muscle actin (αSMA), vascular cell adhesion molecule-1 (VCAM1), and receptor activator of NF-κB ligand (RANKL). Within these cell layers, osteoclasts were found near endomucin-reactive blood vessels. In PTH-administered femora, osteocytes secreted Dkk1, a Wnt inhibitor that affects angiogenesis, and blood vessels exhibited plasmalemma vesicle-associated protein, an angiogenic molecule. In summary, endomucin-positive blood vessels, when accompanied by osteoclasts in the ALP/αSMA/VCAM1/RANKL-reactive osteoblastic cell layers, invade the cortical bone, potentially due to the action of osteocyte-derived molecules such as DKK1.

Revealing intermetallic strengthening in bainitic steel designed for nickel aluminide formation

BainNiAlCu steel was designed to achieve a cementite-free bainitic structure and susceptibility to the formation of intermetallic phases at elevated temperatures. Based on Transmission Electron Microscopy (TEM) observations, the intermetallic strengthening occurring in the bainitic ferrite matrix was revealed. The B2-ordered phase are rich in Ni, Al, and Cu, which indicates the growth of NiAl/Cu co-precipitates. The intermetallic phase was characterized by a spherical morphology and nanometer size. The micro-segregation of Ni, Al and Cu was observed at the boundaries of cementite particles and the bainitic matrix. The redistribution of atoms during the growth of carbides forms a heterogeneous nickel aluminide nucleation site. Intermetallic strengthening is a promising strategy for controlling the thermal stability of bainitic structures. The results of this research constitute fundamental knowledge regarding the design of ultra-fine, cementite-free bainitic steels subjected to intermetallic strengthening.

The freeze-thaw cycle exacerbates the ecotoxicity of polystyrene nanoplastics to Secale cereale L. seedlings

In the context of global climate change, recurrent freeze-thaw cycles (FTC) and concurrent exposure to polystyrene nanoplastics (PSNPs) directly impact crop growth and indirectly affect resilience to abiotic stress. In January 2023, experiments at the Environmental Biology Laboratory, Jilin University, Changchun, China, exposed rye seedlings to 100 nm PSNPs at concentrations of 0, 10, 50, and 100 mg/L for seven days, followed by three FTC. Scanning electron microscopy (SEM) demonstrated that PSNPs migrated from the roots to the leaves, with FTC significantly exacerbating their accumulation within plant tissues. Transmission electron microscopy (TEM) observations showed that FTC disrupted normal cell division, and combined stress from NPs damaged plant organs, particularly chloroplasts, thereby substantially inhibiting photosynthesis. FTC delayed plant phenological stages. Under combined stress, malondialdehyde (MDA) accumulation in plant tissues increased by 15.6%, while hydrogen peroxide (H2O2) content decreased. Simultaneously, the activities of peroxidase (POD) and catalase (CAT) increased by 34.2% and 38.6%, respectively. Molecular docking unveiled that PSNPs could bind to the active center of POD/CAT through hydrogen bonding or hydrophobic interactions. The Integrated Biomarker Response (IBR) index highlighted FTC as a crucial determinant for pronounced effects. Moreover, an apparent dose-dependent effect was observed, with antioxidant enzyme activities in rye seedlings induced by low pollutant concentrations and inhibited by high concentrations. These results indicate that FTC and PSNPs can disrupt plant membrane systems and cause severe oxidative damage. Overall, this study provides compelling scientific evidence of the risks associated with NPs exposure in plants subjected to abiotic stress.

Co-deposited layers on gap surfaces of bulk tungsten divertor tiles in JET ITER-like wall: Directional effects and nanostructures

Co-deposited layers on surfaces of bulk tungsten divertor tiles (W lamellae) from the first campaign of JET with the ITER-Like Wall (JET-ILW, 2011–2012) were examined by means of a cross-sectional transmission electron microscope observation. The focus was on geometrical effects in impurity deposition, mainly beryllium (Be), on surfaces located in the poloidal gap separating adjacent lamellae. The study was carried out on the sides (gap surfaces) of two W lamellae from Stack C (located on the outboard part of the horizontal section of the lower divertor), from the region most exposed to the plasma (lamellae C23) and in the magnetic shadow of the upstream divertor module (lamellae C3). The tile manufacturing process (cold rolling) left shallow grooves, i.e. structures classified as convex (hill) and concave (valley) regions. These regions are decisive for the deposition structure. The main results were: (i) two kinds of impurity deposition features, “homogeneous” and “directional”, have been distinguished; (ii) the directional ones were characterized by nanoscale inclined vertical stripes in the deposition layer; (iii) homogeneous deposition without directional features were in the valley region. The results clearly indicate the impact of the surface finish, even in the tile gaps, on the qualitative and quantitative aspects of deposition.

Green-synthesized lignin nanoparticles enhance Zea mays resilience to salt stress by improving antioxidant metabolism and mitigating ultrastructural damage

Soil salinity poses a substantial threat to agricultural productivity, resulting in far-reaching consequences. Green-synthesized lignin nanoparticles (LNPs) have emerged as significant biopolymers which effectively promote sustainable crop production and enhance abiotic stress tolerance. However, the defensive role and underlying mechanisms of LNPs against salt stress in Zea mays remain unexplored. The present study aims to elucidate two aspects: firstly, the synthesis of lignin nanoparticles from alkali lignin, which were characterized using field emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), Fourier Infrared Spectroscopy (FT-IR) and Energy Dispersive X-Ray Spectroscopy (EDX). The results confirmed the purity and morphology of LNPs. Secondly, the utilization of LNPs (200 mg/L) in nano priming to alleviate the adverse effects of NaCl (150 mM) on Zea mays seedlings. LNPs significantly reduced the accumulation of Na+ (17/21%) and MDA levels (21/28%) in shoots/roots while increased lignin absorption (30/31%), resulting in improved photosynthetic performance and plant growth. Moreover, LNPs substantially improved plant biomass, antioxidant enzymatic activities and upregulated the expression of salt-tolerant genes (ZmNHX3 (1.52 & 2.81 FC), CBL (2.83 & 3.28 FC), ZmHKT1 (2.09 & 4.87 FC) and MAPK1 (3.50 & 2.39 FC) in both shoot and root tissues. Additionally, SEM and TEM observations of plant tissues confirmed the pivotal role of LNPs in mitigating NaCl-induced stress by reducing damages to guard cells, stomata and ultra-cellular structures. Overall, our findings highlight the efficacy of LNPs as a practical and cost-effective approach to alleviate NaCl-induced stress in Zea mays plants. These results offer a sustainable agri-environmental strategy for mitigating salt toxicity and enhancing crop production in saline environments.

Optimized carbon extraction replicas for transmission electron microscopy of nanoprecipitates in microalloyed low-carbon steels

Nanoprecipitates play a decisive role in strengthening of microalloyed low-carbon steels. The direct carbon extraction replica (CER) method is a promising way to extract the nanoprecipitates from the surrounding iron matrix for a detailed characterization of their structure and chemistry using electron microscopy. Better results can generally be obtained by electron microscopy when the magnetic matrix is removed. However, there are challenges in the preparation of relatively thin CERs, especially during stripping and cleaning stages of the procedure. In this contribution, a systematic study of different parameters associated with the direct CER preparation method was performed on a vanadium-microalloyed low-carbon model steel to improve the replication procedure. Relatively low nanoscale surface kurtosis of the iron matrix with respect to the thickness of the deposited carbon layer was found to be important for successful replications from different crystallographic planes of the matrix during the stripping stage. Furthermore, modified water-based stripping and cleaning solutions were introduced that minimized wrinkling, coalescence, and disintegration of ∼8 nm thick CERs. These results are supported by (scanning) transmission electron microscopy observations, which showed successful extraction of V-rich nanoprecipitates in a size range of 1–50 nm from both the ferritic and bainitic microstructures. The modified method improves the common direct CER preparation procedure and can be used to study precipitates in a wide range of microalloyed low-carbon steels.

Alkyl anchor–modified artificial viral capsid budding outside-to-inside and inside-to-outside giant vesicles

Alkyl anchor–modified artificial viral capsid budding outside-to-inside and inside-to-outside giant vesicles

Se (IV)-Doped Monodisperse Spherical TiO <sub>2</sub> Nanoparticles for Adhesively Bonded Joint Reinforcing: Synthesis and Characterization

<div>This study focused on the synthesis and characterization of monodisperse spherical TiO<sub>2</sub> nanoparticles doped on the surface with Se (IV) in order to increase the mechanical properties of the bonded joint reinforcing. Work will begin with the synthesis of monodisperse quasi-spherical TiO<sub>2</sub> nanoparticles with a modal diameter of less than 20 nm, using the sol-gel technique. Se (IV) selenium surface doping changed the specimen’s chemistry and physics. Different initial concentrations of the doping element will be tested. Next, a physicochemical characterization of the different solid systems will be carried out in order to determine the effect of the doping element on the properties of titanium dioxide. Their morphology and size will be studied through transmission electron microscope observations; volume chemical composition by X-ray diffraction analysis, EDX (energy-dispersive X-ray), and XRF (X-ray fluorescence). The careful selection of 4% and 6% concentrations produced the optimum nanoparticle increase and cohesive structure preservation. These findings demonstrate that Se (IV)-doped monodisperse spherical TiO<sub>2</sub> nanoparticles may improve adhesive junction mechanical properties, enabling the development of better adhesive formulations.</div>

Staggered structural dynamic-mediated selective adsorption of H2O/D2O on flexible graphene oxide nanosheets

Graphene oxide (GO) is the one of the most promising family of materials as atomically thin membranes for water-related molecular separation technologies due to its amphipathic nature and layered structure. Here, we show important aspects of GO on water adsorption from molecular dynamics (MD) simulations, in-situ X-ray diffraction (XRD) measurements, and ex-situ nuclear magnetic resonance (NMR) measurements. Although the MD simulations for GO and the reduced GO models revealed that the flexibility of the interlayer spacing could be attributed to the oxygen-functional groups of GO, the ultra-large GO model cannot well explain the observed swelling of GO from XRD experiments. Our MD simulations propose a realistic GO interlayer structure constructed by staggered stacking of flexible GO sheets, which can explain very well the swelling nature upon water adsorption. The transmission electron microscopic (TEM) observation also supports the non-regular staggered stacking structure of GO. Furthermore, we demonstrate the existence of the two distinct types of adsorbed water molecules in the staggered stacking: water bonded with hydrophilic functional groups and “free” mobile water. Finally, we show that the staggered stacking of GO plays a crucial role in H/D isotopic recognition in water adsorption, as well as the high mobility of water molecules.

Systematic study of FIB-induced damage for the high-quality TEM sample preparation

Nowadays, a focused Ga ion beam (FIB) with a scanning electron microscopy (SEM) system has been widely used to prepare the thin-foil sample for transmission electron microscopy (TEM) or scanning TEM (STEM) observation. An establishment of a solid strategy for a reproducible high-quality sample preparation process is essential to carry out high-quality (S)TEM analysis. In this work, the FIB damages introduced by Ga+ beam were investigated both experimentally and stopping and range of ions in matter (SRIM) simulation for silicon (Si), gallium nitride (GaN), indium phosphide (InP), and gallium arsenide (GaAs) semiconductors. It has been revealed that experimental investigations of the FIB-induced damage are in good agreement with SRIM simulation by defining the damage as not only “amorphization” but also “crystal distortion”. The systematic evaluation of FIB damages shown in this paper should be indispensable guidance for reliable (S)TEM sample preparation.

Enhancement of superconductivity and phase diagram of Ta-doped Kagome superconductor CsV3Sb5

Kagome superconductors AV3Sb5 (A = K, Rb, and Cs) have attracted enormous interest due to the coexistence of charge density wave (CDW) order, unconventional superconductivity (SC) and anomalous Hall effect (AHE). In this paper, we reported an intensive investigation on Cs(V1−xTax)3Sb5 single crystals with systematic Ta doping. Ta was confirmed to be doped into V-site in the Kagome layer from both single crystal X-ray diffraction structural refinement and scanning transmission electron microscopy observation. The highest Ta doping level was found to be about 16%, which is more than twice as much as 7% in Nb-doped CsV3Sb5. With the increase of Ta doping, CDW order was gradually suppressed and finally vanished when the doping level reached to more than 8%. Meanwhile, superconductivity was enhanced with a maximum critical temperature (Tc) of 5.3 K, which is the highest Tc in the bulk crystal of this Kagome system at ambient pressure so far. The μ0Hc2(T) behavior demonstrates that the system is still a two-band superconductor after Ta doping. Based on the electrical transport measurement, a phase diagram was set up to exhibit the evolution of CDW and SC in the Cs(V1−xTax)3Sb5 system. These findings pave a new way to search for new superconductors with higher Tc in the AV3Sb5 family and establish a new platform for tuning and controlling the multiple orders and superconducting states.

Resolving the long-standing discrepancy in Fe3Al ordering mobilities: A synergistic experimental and phase-field study

This study addressed the long-standing challenge of determining the growth kinetic of Antiphase Domains (APDs) with D03-ordered structure in Fe3Al by the combination of phase-field (PF) simulations and transmission electron microscopy (TEM) observation. The “shape coefficient” which correlates the growth rate of APD with 3-dimensional intricate shape and the shrinking rate of 2-dimensional circular antiphase boundaries (APBs) in thin film was assessed through a comparative analysis of PF simulations involving the shrinking of 2D circular APBs and the growth of 3D APDs emerged from a disordered state. Simultaneously, the increase rate in APD size in bulk samples after heat treatment was measured using TEM. By incorporating the calculated shape coefficient and experimental data on APD growth rates, we successfully derived accurate values of mobility for forming D03 type ordered structure. The ordering mobilities evaluated by this approach align more closely with those obtained through traditional X-ray powder diffraction of order-order relaxation rather than those obtained through in-situ TEM observation. This finding lays the foundation for optimizing heat treatment conditions to regulate APD structure and enhance the superelasticity of Fe3Al primarily due to the interaction between dislocation and APBs. This methodology can be extended to estimate the ordering mobility of other intermetallic.

Cyclic Failure of a Cr–Au Bilayer on Polyimide: In Situ Transmission Electron Microscopy Observations of Interfacial Dislocation Mechanisms

This work presents in situ transmission electron microscopy observations of dislocation activities and associated fatigue properties in a cross‐sectional sample of a Cr–Au bilayer on a polyimide substrate under cyclic loading. Dislocation structures in the Au layer are observed to evolve into a geometrically necessary boundary parallel to the Cr–Au interface, which significantly impedes dislocation motion and plays a crucial role in enhancing the fatigue resistance of the studied sample. While a comparison to the damage in a conventional blanket film testing geometry reveals some differences in the accumulation of plastic flow, the findings can provide insights into the underlying mechanisms governing fatigue in nanostructured multilayer materials on polymer substrates.

Replicating Human Characteristics: A Promising Animal Model of Central Fatigue.

Central fatigue is a common pathological state characterized by psychological loss of drive, lack of appetite, drowsiness, and decreased psychic alertness. The mechanism underlying central fatigue is still unclear, and there is no widely accepted successful animal model that fully represents human characteristics. We aimed to construct a more clinically relevant and comprehensive animal model of central fatigue. In this study, we utilized the Modified Multiple Platform Method (MMPM) combined with alternate-day fasting (ADF) to create the animal model. The model group rats are placed on a stationary water environment platform for sleep deprivation at a fixed time each day, and they were subjected to ADF treatment. On non-fasting days, the rats were allowed unrestricted access to food. This process was sustained over a period of 21 days. We evaluated the model using behavioral assessments such as open field test, elevated plus maze test, tail suspension test, Morris water maze test, grip strength test, and forced swimming test, as well as serum biochemical laboratory indices. Additionally, we conducted pathological observations of the hippocampus and quadriceps muscle tissues, transmission electron microscope observation of mitochondrial ultrastructure, and assessment of mitochondrial energy metabolism and oxidative stress-related markers. The results revealed that the model rats displayed emotional anomalies resembling symptoms of depression and anxiety, decreased exploratory behavior, decline in learning and memory function, and signs of skeletal muscle fatigue, successfully replicating human features of negative emotions, cognitive decline, and physical fatigue. Pathological damage and mitochondrial ultrastructural alterations were observed in the hippocampus and quadriceps muscle tissues, accompanied by abnormal mitochondrial energy metabolism and oxidative stress in the form of decreased ATP and increased ROS levels. In conclusion, our ADF+MMPM model comprehensively replicated the features of human central fatigue and is a promising platform for preclinical research. Furthermore, the pivotal role of mitochondrial energy metabolism and oxidative stress damage in the occurrence of central fatigue in the hippocampus and skeletal muscle tissues was corroborated.

Mitochondrial damage and activation of NLRP3 induced by Yersinia ruckeri infection play an important role in the occurrence of diffuse acute inflammation of channel catfish (Ictalurus punctatus)

Yersinia ruckeri, as a facultative intracellular pathogen, can cause two different infection phenotypes of fish. An important phenotype is diffuse acute inflammation (DAI), which is mainly characterized by systemic hemorrhage and multiple tissues damage. Another phenotype is enteric redmouth symptom (EM) with predominantly digestive system damage, while slight damage to other tissues and organs. At present, the causes and mechanisms of heterogeneity of Y. ruckeri infection are not clear. According to our previous research and related bioinformatics analysis, it is suggested that the heterogeneity of infection of Y. ruckeri may be related to the activation of intracellular pattern recognition receptor (NLRP3). Furthermore, combined with the transmission electron microscope observation and ultrastructural pathological analysis of DAI and EM phenotypes, it is hypothesized that Y. ruckeri infection may mediate the occurrence of DAI by inducing mitochondrial damage and activation of NLRP3. In this study, we established DAI and EM phenotypes of channel catfish (Ictalurus punctatus) through the artificial infection experiment. Subsequently, we observed the pathological changes and characteristics of different tissues in DAI and EM phenotypes, such as liver, spleen, kidney, intestine and gill. In addition, the mitochondrial damage of head kidney mediated by Y. ruckeri infection was confirmed by transmission electron microscope observation. Furthermore, by detecting the expression of proinflammatory factors and related pattern recognition receptors in various tissues, we preliminarily clarified the molecular characteristics of immune response in DAI and EM phenotype fish. Moreover, the head kidney macrophages isolated from DAI and EM were observed through transmission electron microscope, and the expression levels of NLRP3, Caspase-1 and IL-1β were detected. Finally, the correlation between mitochondrial damage induced by Y. ruckeri infection and NLRP3 signal transduction was preliminary revealed. Taken together, our results showed that the inflammatory DAI phenotype of fish mediated by Y. ruckeri infection is closely related to mitochondrial damage and NLRP3 activation, which will provide theoretical basis for further study on the pathogenic mechanism of Y. ruckeri infection and clinical diagnosis of the disease, and also provide some insights into the role of NLRP3 in the natural immunity of aquatic animals.