Single-image based deep learning for precise atomic defects identification

Defect engineering has been profoundly employed to confer desirable functionality to materials that pristine lattices inherently lack. Although single atomic-resolution scanning transmission electron microscopy (STEM) images are widely accessible for defect engineering, harnessing atomic-scale images containing various defects through traditional image analysis methods is hindered by random noise and human bias. Yet the rise of deep learning (DL) offering an alternative approach, its widespread application is primarily restricted by the need for large amounts of training data with labeled ground truth. In this study, we propose a two-stage method to address the problems of high annotation cost and image noise in the detection of atomic defects in monolayer 2D materials. In the first stage, to tackle the issue of data scarcity, we employ a two-state transformation network based on U-GAT-IT for adding realistic noise to simulated images with pre-located ground truth labels, thereby infinitely expanding the training dataset. In the second stage, atomic defects in monolayer 2D materials are effectively detected with high accuracy using U-Net models trained with the data generated in the first stage, avoiding random noise and human bias issues. In both stages, we utilize segmented unit-cell-level images to simplify the model's task and enhance its accuracy. Our results demonstrate that not only sulfur vacancies, we are also able to visualize oxygen dopants in monolayer MoS2, which are usually overwhelmed by random background noise. As the training was based on a few segmented unit-cell-level realistic images, this method can be readily extended to other 2D materials. Therefore, our results outline novel ways to train the model with minimized datasets, offering great opportunities to fully exploit the power of machine learning (ML) applicable to a broad materials science community

Electroacupuncture Promotes Proliferation of Amplifying Neural Progenitors and Preserves Quiescent Neural Progenitors from Apoptosis to Alleviate Depressive-Like and Anxiety-Like Behaviours

The present study was designed to investigate the effects of electroacupuncture (EA) on depressive-like and anxiety-like behaviours and neural progenitors in the hippocampal dentate gyrus (DG) in a chronic unpredictable stress (CUS) rat model of depression. After being exposed to a CUS procedure for 2 weeks, rats were subjected to EA treatment, which was performed on acupoints Du-20 (Bai-Hui) and GB-34 (Yang-Ling-Quan), once every other day for 15 consecutive days (including 8 treatments), with each treatment lasting for 30 min. The behavioural tests (i.e., forced swimming test, elevated plus-maze test, and open-field entries test) revealed that EA alleviated the depressive-like and anxiety-like behaviours of the stressed rats. Immunohistochemical results showed that proliferative cells (BrdU-positive) in the EA group were significantly larger in number compared with the Model group. Further, the results showed that EA significantly promoted the proliferation of amplifying neural progenitors (ANPs) and simultaneously inhibited the apoptosis of quiescent neural progenitors (QNPs). In a word, the mechanism underlying the antidepressant-like effects of EA is associated with enhancement of ANPs proliferation and preserving QNPs from apoptosis

Activation of P2X7 receptor and NLRP3 inflammasome assembly in hippocampal glial cells mediates chronic stress-induced depressive-like behaviors

Abstract Background In recent years, proinflammatory cytokine interleukin-1β (IL-1β) was considered to play a critical role in the pathogenesis of depression. In addition, P2X7 receptor (P2X7R), a member of the purinergic receptor family, which is predominantly present on microglia, as well as on astrocytes and neurons in lesser amounts in the central nervous system, was suggested to be involved in the processing and releasing of IL-1β. Here, we investigated the role of P2X7R in the pathogenesis of depression. Methods Male Sprague-Dawley rats were subjected to chronic unpredictable stressors (CUS) for 3 weeks. At the end of week 1, 2, and 3, extracellular ATP, caspase 1, IL-1β, and components and activation of NLRP3 inflammasome (nucleotide-binding, leucine-rich repeat, pyrin domain containing 3) were evaluated as biomarker of neuroinflammation. In separate experiments, the rats were microinjected with P2X7R agonists ATP, BzATP, and saline into the hippocampus, respectively, or exposed to CUS combined with hippocampal microinjection with P2X7R antagonist, BBG and A438079, and saline, respectively, for 3 weeks, followed by exposed to forced swimming test and open-field test. Moreover, we also evaluated the depressive and anxiety-like behavior of P2X7-null mice in forced swimming test, open-field test, and elevated plus maze. Results Along with stress accumulation, extracellular ATP, cleaved-caspase 1, IL-1β, and ASC were significantly enhanced in the hippocampus, but P2X7R and NLRP3 were not. Immunoprecipitation assay indicated that along with the accumulation of stress, assembly of NLRP3 inflammasome and cleaved caspase 1 in NLRP3 inflammasome were significantly increased. Moreover, antagonists of P2X7R, either BBG or A438079, prevented the development of depressive-like behaviors induced by chronic unpredictable stress in rats. Meanwhile, we could not observe any depressive-like or anxiety-like behaviors of P2X7-null mice after they had been exposed to CUS. The results implied that P2X7 knockout could impede the development of depressive-like and anxiety-like behaviors induced by CUS. In contrast, chronic administration of agonists of P2X7R, either ATP or BzATP, could induce depressive-like behaviors. Conclusions The activation of P2X7R and subsequent NLRP3 inflammasome in hippocampal microglial cells could mediate depressive-like behaviors, which suggests a new therapeutic target for the prevention and treatment of depression

Carbon Nanotube-Directed 7 GPa Heterocyclic Aramid Fiber and Its Application in Artificial Muscles

Poly(p-phenylene-benzimidazole-terephthalamide) (PBIA) fibers with excellent mechanical properties are widely used in fields that require impact-resistant materials such as ballistic protection and aerospace. The introduction of heterocycles in polymer chains increases their flexibility and makes it easier to optimize the fiber structure. However, the inadequate orientation of polymer chains is one of the main reasons for the large difference between the measured and theoretical mechanical properties of PBIA fibers. Herein, carbon nanotubes (CNTs) are selected as an orientation seed. Their structural features allow CNTs to orient during the spinning process, which can induce an orderly arrangement of polymers and improve the orientation of the fiber microstructure. To ensure the complete 1D topology of long CNTs (approximate to 10 mu m), PBIA is used as an efficient dispersant to overcome dispersion challenges. The p-CNT/PBIA fibers (10 mu m single-walled carbon nanotube 0.025 wt%) exhibit an increase of 22% in tensile strength and 23% in elongation, with a maximum tensile strength of 7.01 +/- 0.31 GPa and a reinforcement efficiency of 893.6. The artificial muscle fabricated using CNT/PBIA fibers exhibits a 34.8% contraction and a 25% lifting of a 2 kg dumbbell, providing a promising paradigm for high-performance organic fibers as high-load smart actuators. The damage-free single-walled carbon nanotubes (SWNTs) dispersed using poly(p-phenylene-benzimidazole-terephthalamide) (PBIA) are selected as the orientation seed to improve the fiber microstructure and the mechanical properties. The p-SWNT/PBIA fibers exhibit an increase of 22% in tensile strength and 23% in elongation, with a maximum tensile strength of 7.01 +/- 0.31 GPa and a reinforcement efficiency of 893.6.imag

Additional file 2: Figure S2. of Activation of P2X7 receptor and NLRP3 inflammasome assembly in hippocampal glial cells mediates chronic stress-induced depressive-like behaviors

There was no significant sexual difference in the mice model of depression induced by chronic unpredictable stress. (A) Experimental paradigm. Wild-type C57BL6/J (WT) male and female mice were exposed to CUS for 35 days. Behavioral indicators were then assessed, including (B) immobility time in forced swimming test (FST) (interaction: F1,34 = 0.0003, p = 0.9857; stress: F1,34 = 26.51, p < 0.0001; sex: F1,34 = 0.4940, p = 0.4869), (C) the number of rearing in open-field test (OFT) (interaction: F1,34 = 0.01154, p = 0.9151; stress: F1,34 = 20.44, p < 0.0001; sex: F1,34 = 0.1414, p = 0.7092), (D) total distance in open-field test (OFT) (interaction: F1,34 = 0.03584, p = 0.8510; stress: F1,34 = 4.501, p = 0.0412; sex: F1,34 = 0.1341, p = 0.7165), (E) open-arm entrance percent in elevated plus maze test (EPM) (interaction: F1,34 = 0.1817, p = 0.6728; stress: F1,34 = 16.47, p = 0.0003; sex: F1,34 = 7.879, p = 0.0084), (F) open-arm time percent in elevated plus maze test (EPM) (interaction: F1,34 = 0.7491, p = 0.3932; stress: F1,34 = 5.100, p = 0.0309; sex: F1,34 = 0.2789, p = 0.6011) n = 8–12 per group, all data are expressed as the mean ± SEM. # p < 0.05, ## p < 0.01, ### p < 0.001, compared to male before CUS. *p < 0.05 and **p < 0.01, compared to female before CUS. (G) Experimental paradigm. Wild-type C57BL6/J (WT) and P2X7-null female mice were exposed to CUS for 35 days. Behavioral indicators were then assessed, including (H) immobility time in forced swimming test (FST) (interaction: F1,23 = 1.038, p = 0.3188; stress: F1,23 = 8.155, p = 0.0089; genotype: F1,23 = 1.610, p = 0.2171), (I) the number of rearing in open-field test (OFT) (interaction: F1,23 = 3.690, p = 0.0672; stress: F1,23 = 3.929, p = 0.0595; genotype: F1,23 = 1.221, p = 0.2805), (J) total distance in open-field test (OFT) (interaction: F1,23 = 4.348, p = 0.0483; stress: F1,23 = 0.2596, p = 0.6153; genotype: F1,23 = 2.684, p = 0.1150), (K) open-arm entrance percent in elevated plus maze test (EPM) (interaction: F1,23 = 5.294, p = 0.0308; stress: F1,23 = 2.595, p = 0.1208; genotype: F1,23 = 1.976, p = 0.1732), and (L) open-arm time percent in elevated plus maze test (EPM) (interaction: F1,23 = 5.914, p = 0.0232; stress: F1,23 = 3.100, p = 0.0916; genotype: F1,23 = 3.463, p = 0.0756). n = 5–8 per group, all data are expressed as the mean ± SEM. # p < 0.05, ## p < 0.01, ### p < 0.001, compared to wild-type before CUS. p < 0.05, comparing genotypes. (TIF 9760 kb

Phase and Composition Engineering of Self-Intercalated 2D Metallic Tantalum Sulfide for Second-Harmonic Generation

Self-intercalation in two-dimensional (2D) materials is significant, as it offers a versatile approach to modify material properties, enabling the creation of interesting functional materials, which is essential in advancing applications across various fields. Here, we define ic-2D materials as covalently bonded compounds that result from the self-intercalation of a metal into layered 2D compounds. However, precisely growing ic-2D materials with controllable phases and self-intercalation concentrations to fully exploit the applications in the ic-2D family remains a great challenge. Herein, we demonstrated the controlled synthesis of self-intercalated H-phase and T-phase Ta1+xS2 via a temperature-driven chemical vapor deposition (CVD) approach with a viable intercalation concentration spanning from 10% to 58%. Atomic-resolution scanning transmission electron microscopy-annular dark field imaging demonstrated that the self-intercalated Ta atoms occupy the octahedral vacancies located at the van der Waals gap. The nonperiodic Ta atoms break the centrosymmetry structure and Fermi surface properties of intrinsic TaS2. Therefore, ic-2D T-phase Ta1+xS2 consistently exhibit a spontaneous nonlinear optical (NLO) effect regardless of the sample thickness and self-intercalation concentrations. Our results propose an approach to activate the NLO response of centrosymmetric 2D materials, achieving the modulation of a wide range of optoelectronic properties via nonperiodic self-intercalation in the ic-2D family

Unveiling Electronic Properties in Metal–Phthalocyanine-Based Pyrazine-Linked Conjugated Two-Dimensional Covalent Organic Frameworks

π-Conjugated two-dimensional covalent organic frameworks (2D COFs) are emerging as a novel class of electro-active materials for (opto-)electronic and chemiresistive sensing applications. However, understanding the intricate interplay between chemistry, structure and conductivity in π-conjugated 2D COFs remains elusive. Here, we report a detailed charac-terization for the electronic properties of two novel samples consisting of Zn- and Cu-phthalocyanine-based pyrazine-linked 2D COFs. These 2D COFs are synthesized by condensation of metal-phthalocyanine (M=Zn and Cu) and pyrene derivatives. The obtained polycrystalline-layered COFs are p-type semiconductors both with a band gap of ~1.2 eV. Mobilities up to ~5 cm²/Vs are resolved in the dc limit, which represent a lower threshold induced by charge carrier localization at crystalline grain boundaries. Hall Effect measurements (dc limit) and terahertz (THz) spectroscopy (ac limit) in combination with den-sity functional theory (DFT) calculations demonstrate that varying metal center from Cu to Zn in the phthalocyanine moiety has a negligible effect in the conductivity (~5×10⁻⁷ S/cm), charge carrier density (~10¹² cm⁻³), charge carrier scattering rate (~3×10¹³ s⁻¹), and effective mass (~2.3m₀) of majority carriers (holes). Notably, charge carrier transport is found to be aniso-tropic, with hole mobilities being practically null in-plane and finite out-of-plane for these 2D COFs

Genetic architecture of the inflammatory bowel diseases across East Asian and European ancestries

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