Electron Microscopy Observations Research Articles

A Facile Strategy for Freeze-Drying Preparation of Silica Aerogel from Sodium Silicate

Silica aerogels have attracted widespread attention for their distinct nanoporous networks, composed of interconnected silica nanoparticles and high-volume nanosized pores. Nonetheless, producing silica aerogels with low costs and simple processes still remains a considerable challenge. Herein, the mesoporous silica aerogels were prepared from inorganic silicon source through the freeze-drying. Using sodium silicate as the silica precursor, the gel was formed by the ion exchange and sol-gel in sequence. The regeneration of the weak acidic ion exchange resin produced the sodium acetate solution, which can be potentially used as carbon source for sewage treatment. To eliminate the collapse of microstructure of the silica hydrogel during freeze-drying, the tert-butanol aqueous solution was used as the freeze-drying medium. Particularly, the direct mixing of tert-butanol and silica sol to generate wet gel avoids prolonged and material-consuming solvent replacement. The pore structure of mesoporous silica aerogel can be adjusted by changing the concentration of tert-butanol solution. The 18 wt% tert-butanol solution results in the most favorable mesoporous structure of silica aerogel, owing to the eutectic behavior within the gel, which was verified by differential scanning calorimetry (DSC) analysis, and also due to the superior and uniform mesoporous structure of wet gel, which was validated by the cryogenic scanning electron microscopy (cryo-SEM) observation. Under optimal process conditions, the obtained silica aerogel exhibited a high porosity (97.74%) and typical mesoporous structure with the large pore volume (4.84 cm3·g-1) and an average pore diameter of 24.40 nm. The proposed cost-effective preparation strategy could elevate the potentials for large scale applications of silica aerogels in the fields of thermal insulation for building, industrial catalysis and adsorption, etc.

Preparation of soybean isolate protein/xanthan gum/agar-Lycium ruthenicum anthocyanins intelligent indicator films and its application in mutton preservation.

The preparation of intelligent indicator films containing anthocyanins and their utilization for real-time monitoring of meat freshness represents a prominent research topic of food packaging. In this study, anthocyanins (ALR) were extracted from Lycium ruthenicum (LR) using solvent extraction. Subsequently, these anthocyanins were incorporated into films composed of soybean isolate protein (SPI), xanthan gum (XG) and agar, resulting in SPI/XG/Agar-ALR pH-responsive intelligent indicator films. The physical properties, structural characterization and application in mutton preservation were evaluated to identify the intelligent indicator films with the optimal addition ratio of ALR. The results indicated that the SPI/XG/Agar-5 % films exhibited exceptional performance in terms of thickness, mechanical properties, water vapor transmission rate, oxygen transmission rate and light transmission rate. Scanning electron microscope observations revealed that the SPI/XG/Agar-5 % films possessed a smooth and flat surface, while fourier transform infrared spectroscopy analysis confirmed their excellent compatibility. The DPPH radical scavenging rate of the SPI/XG/Agar-5 % film reached 80.75 ± 0.63 %. When applied to the preservation of mutton, the SPI/XG/Agar-5 % film significantly extended the shelf life and effectively monitored the freshness of the meat. This study not only broadens the application scope of Lycium ruthenicum anthocyanins but also provides a foundation for the development of smart packaging materials.

Exploring the correlation between variants selection and applied stress in IN718 through transmission electron microscopic analysis

Both tensile and rupture strength of Inconel 718 (IN718) are influenced by the morphology and volume fraction of γ′′ precipitates. This study investigated the preferrable coarsening behaviors of γ′′ precipitation affected by applied stress during aging. Neutron diffraction reveals the clear presence of {004}, {204}and {116} peaks of the γ′′ precipitates in the specimens aged under 300 MPa, compared to the one without stress. Scanning Electron Microscopy and Electron Backscatter Diffraction analyses have demonstrated that the stress applied promote a selective alignment of the γ′′ precipitates, to the detriment of alternative variants. The growth of preferential variants is correlated with the angle between the stress direction and the orientation of face-centered cubic nickel matrix. Crystals adhere to this pattern with misorientation angles within 15° for the {100}γ, {110}γ, {111}γ, and {311}γ planes. Transmission electron microscopy observations coupled with growth free energy calculations have elucidated that the central region of the variants experiences tensile stress exerted by the matrix under applied stress. Concurrently, the energetic barrier at the variant tips is notably reduced. This energetic disparity accounts for the observed preferential growth of variants along their axial direction.

Unexpected nanoscale CeO2 structural transformations induced by ecologically relevant phosphate species

In the present study, the dissolution and microstructural transformation of CeO2 nanoparticles (NPs) in a phosphate-containing milieu were investigated. The dissolution behaviour of 2 nm and 5 nm CeO2 NPs in phosphate buffer solutions was found to differ markedly from that observed in 0.01 M NaClO4. Through synchrotron X-ray diffraction analysis and X-ray absorption spectroscopy, the interaction between CeO2 NPs and phosphate species was examined, revealing the transformation of the oxide into sodium-cerium double phosphate, with cerium predominantly existing in the Ce(IV) state. According to scanning and transmission electron microscopy observations, thus formed Na-Ce(IV) phosphate consists of spindle-like aggregates of nanocrystalline rods, presumably formed during phosphate anions sorption on the initial CeO2 surface. Pair distribution function analysis revealed that Na-Ce(IV) phosphate has a three-dimensional framework crystal structure, similar to NaTh2(PO4)3, as reported earlier, with large channels along the c-axis containing disordered sodium atoms. This study represents the first detailed analysis of phosphate-induced speciation and microstructural transformation of CeO2 NPs, resulting in the formation of Ce(IV) phosphate. Similar processes may occur in natural ecosystems upon the introduction of CeO2 NPs.

Increasing the adhesion of graphene on quartz through fluorination

Graphene was the first 2D-material ever discovered, and its unique properties open up for many applications. Due to its high mechanical resistance and transparency, it has been investigated as a coating for optical devices such as windows or lenses. A particular focus has been as an anti-icing coating where graphene functionalized with fluorine atoms, so-called fluorinated graphene, has been demonstrated to inhibit ice formation. However, to function as a durable coating the adhesion between graphene and the underlying substrate must be strong. Up till now it has not been possible to deposit graphene/functionalized graphene on a transparent substrate, such as SiO2, with strong adhesion, without an intermediate metal layer (that gradually makes it opaque). Through optical and electron microscopy observation of surfaces scratched with a sapphire tip, we show how a transparent, functionalized graphene coating with improved adhesion can be created through fluorination of graphene transferred onto a quartz substrate (α-SiO2). The fluorination leads to an increase in adhesion of approximately 3 times compared to unfluorinated graphene adhered to the same substrate. Comparing this with reported adhesion energies for graphene on SiO2 gives an estimated adhesion energy between 0.03J/m2 and 9J/m2 for graphene fluorinated on SiO2.

A new nanoindentation approach for determining both indentation size effect and continuous apparent activation volume during loading of nanocrystalline Ni and Ni-20 wt.% Fe alloy

A new nanoindentation approach is developed in this study to determine both indentation size effect (ISE) and continuous apparent activation volume () during loading of nanocrystalline nickel (NC Ni) and nanocrystalline nickel-20 wt.% iron alloy (NC Ni-Fe alloy). This approach involves conducting nanoindentation tests under loading modes controlled by both constant strain rate (CSR) and constant loading rate (CLR). Firstly, a new empirical expression for the parameter in the modified Nix-Gao model is established to study the strain rate dependence of the ISEs created in the CSR and CLR tests. Then, continuous data of each individual sample (indentation) during loading are obtained in the CLR test through the alternative use of continuous stiffness measurement technique. The stress dependence of is analyzed based on Duhamel et al.’s model, which considers the role of vacancies generated during inhomogeneous dislocation nucleation. Finally, based on the above experimental and theoretical work as well as transmission electron microscopy observation, the influences of loading mode, loading rate, and material properties (stacking fault energy) on resulting intrinsic hardness of NC Ni and NC Ni-Fe alloy are analyzed. The nanoindentation approach developed in this study provides profound insights into the mechanical behaviors during loading and underlying mechanisms of materials.

Exceptional High-Temperature Strength of a Mo-11%Hf binary alloy

The Mo-rich side of the Mo-Hf binary system exhibits a wide solubility range, up to ∼12 at% Hf at 25°C and increasing to 28% at 2165°C, in spite of the large difference in atomic sizes and elastic moduli of these elements. As a result, strong solid solution strengthening is expected and of interest for high temperature structural applications. In this work, microstructure and mechanical properties of a binary solid solution alloy Mo-11%Hf are reported after annealing at 1400°C for 5-50 hours followed by either slow cooling (SC) or water quenching (WQ). In all annealing conditions, the alloy had remnants of a dendritic structure that formed during solidification, with dendrite cores depleted in Hf and inter-dendritic continuous channels enriched with Hf. Both dendrite cores and Hf-rich channels had BCC crystal structures with similar lattice parameters and the same crystal orientation within each grain. In SC condition, Mo-11%Hf had a yield stress of 920 MPa at 25°C, which decreased to 550 MPa at 600°C, remained nearly constant up to 1200°C and then decreased to 420 MPa at 1400°C. The WQ condition was slightly stronger at 25 - 1000°C, but it was similar to SC condition at higher temperatures. The alloy showed noticeable strain hardening at all studied temperatures. Transmission electron microscopy observations showed that the deformation microstructure consisted predominantly of long bowed edge dislocations. The temperature dependence of the yield stress of the Mo-11%Hf was satisfactorily described by the Maresca-Curtin edge dislocation strengthening model.

Melatonin Ameliorates Cadmium Toxicity in Tobacco Seedlings by Depriving Its Bioaccumulation, Enhancing Photosynthetic Activity and Antioxidant Gene Expression.

Soil remediation for cadmium (Cd) toxicity is essential for successful tobacco cultivation and production. Melatonin application can relieve heavy metal stress and promote plant growth; however, it remains somewhat unclear whether melatonin supplementation can remediate the effects of Cd toxicity on the growth and development of tobacco seedlings. Herein, we evaluated the effect of soil-applied melatonin on Cd accumulation in tobacco seedlings, as well as the responses in growth, physiological and biochemical parameters, and the expression of stress-responsive genes. Our results demonstrate that melatonin application mitigated Cd stress in tobacco, and thus promoted plant growth. It increased root fresh weight, dry weight, shoot fresh weight and dry weight by 58.40%, 163.80%, 34.70% and 84.09%, respectively, compared to the control. Physiological analyses also showed significant differences in photosynthetic rate and pigment formation among the treatments, with the highest improvements recorded for melatonin application. In addition, melatonin application alleviated Cd-induced oxidative damage by reducing MDA content and enhancing the activities of enzymatic antioxidants (CAT, SOD, POD and APX) as well as non-enzymatic antioxidants (GSH and AsA). Moreover, confocal microscopic imaging confirmed the effectiveness of melatonin application in sustaining cell integrity under Cd stress. Scanning Electron Microscopy (SEM) observations illustrated the alleviative role of melatonin on stomata and ultrastructural features under Cd toxicity. The qRT-PCR analysis revealed that melatonin application upregulated the expression of photosynthetic and antioxidant-related genes, including SNtChl, q-NtCSD1, NtPsy2 and QntFSD1, in tobacco leaves. Together, our results suggest that soil-applied melatonin can promote tobacco tolerance to Cd stress by modulating morpho-physiological and biochemical changes, as well as the expression of relevant genes.

Activation of peroxymonosulfate by MnOOH/g-C3N5: Study on highly selective removal of phenolic pollutants and its non-radical pathway

In this research, the MnOOH/g-C3N5 material was successfully synthesized, demonstrating its efficacy in selectively removing phenolic organic pollutants. This material outperformed traditional free radical pathways, exhibiting higher selectivity, enhanced persulfate utilization efficiency, and strong resistance to background anions and complex organic matter. Using phenol as the target pollutant, the MnOOH/g-C3N5/PMS system achieved 81 % mineralization, a PMS utilization efficiency of 88 %, and a 75 % process unit energy consumption value in degrading phenol. This efficient degradation is attributed to the synergistic effects of high-valence metal oxides (MnV(O)/MnIV(O)), singlet oxygen (1O2), and electron transfer complexes, as confirmed by electrochemical analysis and In-situ EPR. Additionally, Transmission Electron Microscopy observations disclosed the development of an amorphous shell on the MnOOH/g-C3N5 surface post-reaction. Electrochemical Impedance Spectroscopy analysis suggested an enhanced charge transfer resistance, further affirming the role of MnOOH/g-C3N5 as an "electron transfer station" in the electron transfer process, accompanied by the formation of electron transfer complexes. This study provides crucial scientific insights and theoretical guidance for applying MnOOH/g-C3N5 materials in environmental engineering.

Effect of the sintering temperature on the electrical properties of Y–Al‐doped ZnO varistors

AbstractTo investigate the relationship between the electrical properties of Y–Al doped ZnO varistors and sintering temperature, in this study, we measured the voltage–current characteristics and electrical performance parameters of samples sintered at –. Scanning electron microscopy observations revealed that as the sintering temperature increased, the grain size grew significantly, leading to a reduction in voltage gradient. Through characteristic testing, X‐ray diffraction and energy dispersive X‐ray spectroscopy analysis, it was found that the increase in sintering temperature promoted the formation of interface negative charge and defect reactions by , increasing and ; tends to aggregate in the grain area, further increasing ; the volatilization of gradually increases, causing a decrease in ; the first increases and then decreases with the changes in and , resulting in a U‐shaped variation characteristic of the nonlinear coefficient and leakage current density. At a sintering temperature of , the performance of ZnO varistors is optimal.

Bromodomain and extraterminal domain (BET) promote autophagy in buffalo sertoli cells

Sertoli cells (SCs) play a pivotal role in spermatogenesis, with autophagy modulation being an evolutionarily conserved mechanism for maintaining cellular homeostasis and protecting spermatogenic cells against apoptosis. The bromodomain and extraterminal domain (BET) family are transcriptional regulators of autophagy. This study investigated the relationship between BET inhibition and autophagy in buffalo SCs. Our findings reveal that BET inhibition suppresses cell proliferation and alters the biological characteristics of SCs. RNA-seq analysis demonstrated significant downregulation of autophagy-related genes upon BET inhibition. Moreover, our bioinformatics analysis suggested the involvement of the PI3K-AKT signaling pathway in autophagy regulation within buffalo SCs. Immunofluorescence and Transmission electron microscopy observations indicated that BET inhibition results in autophagosome accumulation and impedes autophagosome-lysosome degradation, thereby compromising autophagy activity and flux. In summary, this study sheds light on the indispensable role of BET proteins in autophagy and paves the way for further investigations into the mechanisms governing BET protein-mediated autophagy regulation and its implications for male reproduction.

Nanocarbon and medicine: polymer/carbon nanotube composites for medical devices

AbstractIn view of wide-ranging application to the biomedical field, this work investigates the mechanical and electrical properties of a composite made of Single Wall Carbon Nanotubes (SWCNT) bundles self-grafted onto a poly-dimethyl-siloxane (PDMS) elastomer, particularly Sylgard 184, that has well assessed biocompatible properties and is commonly used in prosthetics. Due to the potential risks associated with the use of carbon nanostructures in implanted devices, we also assess the viability of cells directly grown on such composite substrates. Furthermore, as the stability of conductive, stretchable devices made of such composite is also crucial to their use in the medical field, we investigate, by different experimental techniques, the grafting of SWCNT bundles deep into PDMS films. Our findings prove that penetration of SWCNT bundles into the polymer bulk depends on heating time and carbon nanotubes can be seen beyond 150 μm from the surface. This is confirmed by direct electron microscopy observation of large bundles as deep as about 20 μm. The composites exhibit reliable mechanical and electrical responses that are more suitable to large and repeated deformation of the polymer with respect to thermoplastic based composites, suggesting a wide potential for their application to stretchable biomedical devices. Aiming at the proposed application of artificial bladders, a bladder prototype made of poly-dimethyl siloxane endowed with a printed SWCNT-based strain sensor was developed.

Effect of ultrasound power on moisture status change of apple by contact ultrasound reinforced far-infrared radiation drying

To explore the effect of ultrasound power on internal water change of apple dried by contact ultrasound enhanced far-infrared radiation drying (CUFRD), the drying characteristics, microstructure, moisture migration, and molecular vibration patterns of apple slices subjected to this process at different ultrasound powers were investigated using low-field nuclear magnetic resonance (LF-NMR), Near-infrared (NIR) and two-dimensional(2D) correlation analysis. With the increase of contact ultrasound (CU) power, the drying times of apple were shortened by 8.69% to 17.39%, respectively. Scanning electron microscopy (SEM) observation indicated that higher CU power resulted in an increase in the number of microporous channels and pore diameter within apple’s internal tissue. The findings of LF-NMR clarified that free water content kept decreasing, while the content of semi-bound water initially increased and then reduced. Magnetic resonance imaging (MRI) images illustrated that higher CU power corresponded to a faster decrease in the redness value of the H+ density map of apple during drying. 2D correlation analysis revealed that the changes in the O-H bonds of apple were prioritized over the C-H bonds during drying process. NIR spectroscopy and LF-NMR heterogeneous correlation spectrograms demonstrated that at wavelengths of 950, 1450, and 1680 nm, the order of changes in water-related functional groups was quadruple-frequency O-H > combination of the first overtone of O-H stretching and OH-bending band > double-frequency C-H. Moreover, with increasing CU power, the vibration of hydrogen-containing functional groups intensified, leading to increased water activity. Thus, CU application could significantly enhance the CUFRD process of apple slices.

Gelatin-Based Polymers Can Be Processed to Highly Resilient Biocompatible Porous Hydrogel Scaffolds for Soft Tissue Regeneration Applications.

Tissue regeneration relies on the mechanical properties of the surrounding environment, and it has already been shown that mechanostimulation is highly dependent on the stiffness of the native biological tissue. The main advantage of injectable hydrogels in medical applications is their ability to be delivered through minimally invasive techniques. Natural polymer-based hydrogels have been widely used in biomedical applications, due to their high biocompatibility, low immunogenicity, and similarity to soft tissues. However, the crucial combination of low stiffness with high resilience has not been achieved for natural polymers. The current study focuses on the development of novel gelatin-based injectable hydrogels for soft tissue regeneration applications, elucidating the effects of the formulation parameters on the resilience, microstructure, biocompatibility, and mechanical properties. Non-foamed hydrogels demonstrated resilience of at least 95%, while porous hydrogels maintained resilience above 90%, allowing them to withstand mechanical stresses and dynamic conditions within the body. The adjustable modulus of these hydrogels provides the necessary flexibility to mimic the mechanical properties of soft and very soft tissues, without compromising resilience. Environmental Scanning Electron Microscopy (ESEM) observations of the porous hydrogels indicated round interconnected pore structures, desired for cell migration and nutrient flow. Biocompatibility tests on fibroblasts and pre-adipocytes confirmed high biocompatibility, both directly and indirectly. In summary, structuring these new hydrogels for achieving adjustable stiffness, along with the excellent resilience and biocompatibility, is expected to enable this new technology to fit various soft tissue regeneration applications.

Enhancement in clinker hydration degrees and later stage-ettringite stability of calcium sulfoaluminate cements by the incorporation of dolomite

The hydration degrees of clinkers and ettringite stability in calcium sulfoaluminate (C S‾ A) cements in the presence of externally supplied dolomite were investigated in this study. The mineralogical and microstructural characteristics of C S‾ A cements containing different dosages of dolomite were characterized using X-ray diffractometry, Rietveld refinement-based quantification analysis, thermogravimetry analysis, mercury intrusion porosimetry, scanning electron microscopy observation, and energy dispersive spectroscopy point analysis. Furthermore, the binder systems were simulated using thermodynamic modeling to observe the phase changes of hydration products and the underlying hydration kinetics. The incorporation of dolomite accelerated clinker consumption and enhanced the stability of ettringite throughout the testing period, due possibly to the nucleation seeding effect and provision of carbonate ions by dolomite. The modeling outcomes showed the stability of ettringite at later stage by the incorporation of dolomite in the simulated timeframe, yet the active dissolution of dolomite assumed in the modeling procedure overestimated the Mg-bearing hydrates in the samples.

Superconducting Boride Nb2IrB2 with Variable and Tunable Stacking Behaviors of Two-Dimensional [Nb-Ir-Nb] Triangular Lattices.

In structures with special geometry lattices, variations in stacking sequences are ubiquitous, yielding many novel structures and functionalities. Despite a wealth of intriguing properties and wide-ranging applications, there remains a considerable gap in understanding the correlation between special geometry lattices and functionalities in borides. Here, we design and synthesize a new superconducting boride Nb2IrB2, with a body-centered orthorhombic structure, consisting of alternating two-dimensional [Nb-Ir-Nb] triple-triangular-lattice-layers and B fragment layers. Advanced aberration-corrected scanning transmission electron microscopy observations show variable stacking configurations between [Nb-Ir-Nb] triple-triangular-lattice layers that can be tuned through synthesis conditions. Density functional theory calculations reveal that the coherent low-energy boundary interface plane of {101} between [11̅1] and [010] domains is responsible for the variable stacking behaviors. Energetically favorable structures are thereby reasonably proposed, based on nanoscale imperfect structure units. These findings provide valuable insights for designing and exploring new structures and functionalities within boride systems involving special geometry lattices.

In situ synthesis, mechanical properties, and reaction mechanism of the WB2–SiC composites

AbstractIn the present work, WB2–SiC composite powders containing 20 vol.% of SiC were in situ synthesized by the boro/carbothermal reduction with WO3, SiO2, B4C, and carbon black as raw materials at 1400°C, 1500°C, and 1600°C, respectively. The as‐synthesized composite powders were then consolidated by spark plasma sintering (SPS) technique to obtain WB2–SiC composite bulk samples. The experimental results showed that the relative density of the WB2–SiC composite ceramic samples achieved in this study was higher than 97.5%. Also, electronic microscopy observations showed that SiO2 had reacted completely during the preparation process, and the SiC grains were homogenously embedded among the WB2 grains with the formation of a three‐dimensional structure. The Vickers hardness and fracture toughness values of the composite ceramic fabricated by powder heat treated at 1400°C were 24.6 ± 0.7 GPa and 5.4 ± 0.7 MPa·m1/2, respectively, which were the highest among three samples prepared in this study.

Effect of precipitate evolution on galvanic corrosion behavior of friction stir welded AA6061-T6 joint after post-weld aging

The microstructural transformation of FSW AA6061-T6 joint after post-weld T6 and its effects on the mechanical properties and corrosion behavior was investigated through electrochemical tests, immersion experiments and transmission electron microscopy (TEM) observation. The research results show that the joint efficiency and strength can be enhanced by post-welding aging. The hardness of SZ is recovered to a level close to that of matrix due to the sufficient precipitation of the effective strengthening phase β''. The main β' precipitate in over-aged HAZ coarsens during post-weld aging and cannot effectively restore strength, resulting in the lowest hardness in HAZ and limited tensile strength of the joint. The presence of macro-galvanic effects in the whole joint was confirmed. In SZ, the highest level of aging characteristics is caused by the highest aging drive due to fully solidified atoms, and is confirmed by the continuous grain boundary precipitates (GBPs) and dense matrix precipitates, which lead to the most positive potentials. Whereas, in HAZ, discrete GBPs and coarsened matrix precipitates indicate over-aged features, which lead to the most negative potentials. The potential difference between SZ and HAZ results in a macro-galvanic effect in the joint, where SZ is protected as the cathode and HAZ is corroded faster as the anode.

One-Pot Hybridization of Microfibrillated Cellulose and Hydroxyapatite as a Versatile Route to Eco-Friendly Mechanical Materials.

Hydroxyapatite was crystallized in an alkaline dispersion of mechanically fibrillated cellulose to prepare their composites with hydroxyapatite contents of 26-86 wt %. The composite powder was uniaxially pressed at 120 °C and 300 MPa to obtain the compacts. Three-point bending tests revealed that the bending strengths of the compacts were 40-100 MPa, and the elastic moduli were 4-9 GPa. The composite containing 43% hydroxyapatite showed the largest bending strength and the largest work of fracture, and the composite containing 62% hydroxyapatite showed the largest elastic modulus. The composites, derived from the bioderived eco-friendly materials, showed the mechanical properties comparable to those of engineering plastics such as polyamide-6. Scanning electron microscopic observation of the fracture surface showed that the organic phase was discontinuous when the hydroxyapatite weight fraction was increased from 43% to 62%, and the compacts with a discontinuous organic phase lost toughness.

MLKL promotes extracellular trap releasing in Vibrio splendidus AJ01-challenged coelomocytes of sea cucumber Apostichopus japonicus

Extracellular traps (ETs) is a novel host-defense mechanism for the immobilization and killing of invading microorganisms, of which pseudokinase mixed lineage kinase-like protein (MLKL) is necessary for ET formation. Here, we aimed to investigate the effects of various stimulations (including classic ET inducers and pathogen) on ET formation in the coelomocytes of invertebrate sea cucumber Apostichopus japonicus. Our results show that stimulation of sea cucumber coelomocytes with phorbol 12-myristate 13-acetate (PMA), zymosan, Vibrio splendidus AJ01, and AJ01 flagella all led to the formation of typical ET fibers, which can be further digested by DNase I. This finding suggests that DNA is an essential component of coelomocyte ETs. Meanwhile, the signals of histones H2A and H2B transferred to extracellular spaces and colocalized with AJ01, which indicates that histones are also crucial components of coelomocyte ETs. Scanning electron microscopy observation and antimicrobial activity analysis successfully revealed that AJ01 was trapped and killed by ET fibers, and this finding implies the antimicrobial role of sea cucumber coelomocyte ETs. More importantly, silencing and inhibition of AjMLKL after AJ01 infection not only considerably depressed ET generation but also increased the survival rate of AJ01. All our results indicate that AjMLKL mediates sea cucumber ET formation and plays critical roles during pathogen infection.