Electron energy-loss spectroscopy (EELS) coupled with scanning transmission electron microscopy (STEM) is a powerful technique to determine materials composition and bonding with high spatial resolution. Noise is often a limitation especially with the increasing sophistication of EELS experiments. The signal characteristics from direct electron detectors provide a new opportunity to design superior denoisers. We have developed a CNN based denoiser, the unsupervised deep video denoiser (UDVD), which can be applied to EELS datasets acquired with direct electron detectors. We described UDVD and explained how to adapt the denoiser to energy-loss spectral series. To benchmark the performance of the denoiser on EELS datasets, we generated and denoised a set of simulated spectra. We demonstrate the charge spreading effect associated with pixel interfaces on direct electron detectors, which leads to artifacts after denoising. To suppress such artifacts, we propose some adjustments. We demonstrate the effectiveness of the denoiser using two challenging real data examples: mapping Gd dopants in CeO₂ nanoparticles and characterizing vibrational modes in hexagonal boron nitride (h-BN) with atomic resolution.

Metallic nanoparticles play important roles in contrast enhancement and medical therapeutics. Understanding the mechanisms of nanoparticle-cell interactions is critical to the future development and utility of nanoparticles in medicine. Cryo-scanning transmission electron microscopy is suitable for collecting data from beam-sensitive biological systems. Detection of nanoparticles in these biological systems in bright-field cryo-scanning transmission electron microscopy is hindered by the vitrified ice surrounding them. Here, we demonstrate the detection of metallic nanoparticles embedded in slabs of ice with different thicknesses of ice for several electron beam fluxes, using the extended ptychographic iterative engine, non-negative matrix factorisation and virtual dark field imaging algorithms.

Rotation of the electron spin in an inhomogeneous magnetic field in the magnetic electron lens causes a partial loss of coherence. Such incoherence entails non-ideal focusing properties of an electron lens. Although this effect should be small in the current electron-optical systems, we show that the effect could be a non-negligible factor in an aberration-corrected system with an electron probe with a large half angle in the future. A semiclassical framework for evaluating the effect is described. We emphasize that the incoherence effect manifests itself for the spin unpolarized electron beam as well.

This study presents an AI-enhanced framework to address key challenges in the quantitative metallographic analysis of pure iron systems. Manual grain size characterization suffers from limited efficiency and reproducibility, while existing computational methods are constrained by scarce data and incomplete grain boundary detection. To overcome these issues, we propose three core innovations. First, a three-stage data synthesis pipeline is developed, incorporating stochastic grain mask generation via denoising diffusion probabilistic models (DDPM) and microstructural translation using a conditional adversarial network, enabling the generation of physically consistent metallographic images. Second, a deep neural network based on a U-Net architecture is trained on a paired and reconstructed dataset, where the topology-awareness emerges from the data pairing and reconstruction objectives. Third, a fully automated grain analysis system is established, based on whole-grain area quantification and twin-grain merging strategies. The proposed methodology effectively resolves longstanding limitations in metallographic analysis related to data scarcity and subjectivity in manual evaluation.

We demonstrate the iterative phase retrieval of DUT-8(Ni) metal-organic framework (MOF) nanocrystals using high-resolution electron diffraction data. The reconstructed images show contrast features associated with the crystal structure, revealing well-resolved metal-containing rows with interpretable shifts. These shifts correspond to previously reported crystal structure disorder within the MOF. Furthermore, electron diffraction patterns display modulations in the low-resolution region, indicative of the rectangular crystal shape. Based on these data, we also successfully reconstructed the crystal shape image, which closely matched the observed form of the crystal.

The morphology of the male reproductive system and sperm of adults of Discodon minutum Pic, 1928 (Elateriformia: Cantharidae) was described using light microscopy (LM) and transmission electron microscopy (TEM). The morphology of the reproductive system and sperm provides information of taxonomic value and reveals aspects of reproductive biology, although such morphological characteristics are poorly understood in Cantharidae. The reproductive system of D. minutum consists of two free testes, each with 28-30 follicles, two vasa deferentia, and three pairs of accessory glands, as well as an ejaculatory duct with its median portion functioning as an ejaculatory pump. It also has two atypical seminal vesicles formed by evaginations at the base of the vasa deferentia, which serve as sperm storage and secretion. The follicles contain developed cyst cells and mature sperm, grouped in a spermatodesma-like cystic bundle. However, sperm are found free and immersed in secretions within the seminal vesicles, whose wall folds indicate an intense exchange of substances, potentially involved in sperm maintenance, with the hemolymph. The sperm ultrastructure resembles that observed in other Elateriformia, characterized by a nucleus positioned laterally to the flagellar components and a similar arrangement of the mitochondrial derivatives and axoneme. However, they differ in the asymmetrical position of the dense bodies and the triangular cross-sectional shape of the dense bodies and the nucleus. Histological confirmation of an ejaculatory pump in D. minutum is the first report of this structure in Elateroidea. Previous descriptions in Elateridae may have misidentified the ejaculatory pumps as "accessory glands of the ejaculatory duct".

The precise thickness determination of free-standing two-dimensional (2D) materials-such as few-layer graphene and molybdenum disulfide (MoS₂)-is achieved using position-averaged convergent beam electron diffraction (PACBED). Experimental PACBED patterns are quantitatively compared with simulated patterns using two distinct evaluation methods: (1) a difference value method (DVM) based on pixel-wise contrast comparison, and (2) a convolutional neural network (CNN) trained on simulated data to predict layer thickness. Optical contrast measurements serve as an independent reference for validating the PACBED-based thickness determination in the few-layer regime. For samples ranging from monolayers up to three layers, both methods demonstrate exact agreement, and up to 10 layers, deviations were not exceeding a single layer. In the further extended thickness range of up to approximately 50 layers, consistent results are obtained, with deviations of no more than two layers between methods. These results confirm that PACBED, combined with either DVM or CNN-based evaluation, offers a reliable, accurate, and non-destructive method for quantifying the thickness of 2D inorganic materials in transmission electron microscopy.

In the study of sintered microstructures, pore size and spatial distribution are relevant for the fabrication of porous structures for filtration, lightweight, and functional applications. Traditional stereology from optical micrographs is used to calculate mean pore size and separation but may result in large systematic error because of complex-shaped porosity. Pore boundary tessellation (PBT) can be used to advance microscopy image analysis by quantifying local spatial homogeneity and minimum 2D pore separation. This study focused on applying and comparing PBT of highly porous metal structures fabricated through Binder Jet Printing and partial sintering, with previous stereological measurements for a Ni-Mn-Ga magnetic shape memory alloy case study. PBT analysis of the tessellated cell pore area fractions indicates that the sintering parameters result in pore section pinch-off, shrinkage, and elimination. At 1070 °C the pore network breaks up without significant pore shrinking. At 1080 °C, the pores shrink but are not systematically eliminated. At 1090 °C the smaller pore sections in the population are preferentially eliminated, after significant shrinkage observed at 0.5 h. The distance in the solid phase between adjacent pore sections (effective cell wall thickness) was also examined. This result was similar to stereological grain size values (±30 %) for intermediate magnifications with pixel-to-μm ratios of ∼2.7, suggesting this method can be used to improve quantitative microscopy for sintered grain size estimation of this alloy, as well as other sintered metals containing grain boundary porosity (confirmed for sintered SS316L literature micrographs).

Electron beam energies in Transmission Electron Microscopes (TEMs) reach the relativistic realm constituting Quantum Electrodynamics (QED) the appropriate framework for the study of electron matter interaction in TEMs. We focus on the inelastic scattering of relativistic electrons from a generic oriented target. The inelastic differential cross section factorizes to the fast electron part which is calculated analytically, and the dynamic form factor of the target, which encodes the response of the medium to the interaction with the beam. The properties of the dynamic form factor of oriented targets are analyzed. We then derive the scattering cross section of electrons by magnetic targets where spin-flip transitions are induced. We comment on the kinematic regimes where the coefficient of the transverse magnetic interaction is amplified compared to the coulomb matrix element.

Advances in transmission electron microscopy under extreme conditions have enabled in situ experiments to capture vast amounts of data on defect evolution. On the other hand, computer vision models such as Mask R-CNN have become popular in the last few years, enabling fast and accurate segmentation of images of different natures. In the present work, we propose a workflow to label, segment, and analyze irradiation-induced defects in TEM images using Mask R-CNN. The work focuses on interpreting bright-field (BF) videos recorded during the irradiation of three different metallic materials. After establishing a baseline dataset based on austenitic stainless steel 316L, we tested small and large models as the backbone of Mask R-CNN and different hyperparameters for training them. Our best model predicts the areal density of defects in 316L with 83.6 % accuracy, measured by a custom metric which assesses cumulative defect area using an ellipsoidal approximation. We tested the generalization limits of the trained model to ensure accurate estimations of key physical metrics, including the foreground fraction occupied by defects, the number of detected particles, and their relative sizes - all of which exhibit relative errors below 5%. At last, the model helps interpret videos concerning two similar irradiation experiments: one with the 16Cr-37Fe-13Mn-34Ni (at. %) alloy, and another with pure Cr. The model's segmentation clearly captures the different nature of defect evolution between different materials, as expected. Moreover, the proposed workflow not only enables consistent, real-time analysis of small defect loops during in situ TEM experiments but also generates the quantitative data needed to refine mesoscale models.

Enhanced green fluorescent proteins (EGFP) emit cathodoluminescence upon irradiation with electron beams. This phenomenon can be leveraged as a promising tool for investigating biological processes. However, bleaching upon electron beam irradiation presents a challenge to its application. In this study, the electron beam resistance of mAzami Green (mAG), a fluorescent protein with higher structural stability than EGFP, was examined. Similar to EGFP, mAG exhibited a red shift and decreased fluorescence intensity upon electron beam irradiation. This decrease in fluorescence intensity was attributed to quenching by two different decomposition processes: direct quenching and redshift. Analysis of the effect of environmental conditions on the electron beam resistance revealed that the electron beam resistance was slightly higher in solution than in the dry state. This is likely because, in a liquid environment, material exchange with the environment facilitates structural repair, resulting in a decrease in the effective intensity decay rate.

A cross-sectional lamella in thickness around 20 ∼ 100 nm is essential for (S)TEM characterizations of micro/nano particles with compositional gradients or structural inhomogeneity including core shell, surface doped and coated structures, or those with excessive thickness in one or more dimensions. Focused ion beam (FIB) remains as the most reliable technique for extracting site-specific, thin cross-sectional TEM samples. However, conventional bulk epoxy resin embedding often compromises precision for site-specific processing due to particle aggregation with surrounded bubble defects resulting in particle detachment, poor observability, and failed sample preparation under ion beam milling. In this paper, we have proposed a thin film embedding-strengthened focused ion beam (FES-FIB) technique to improve precision for site-specific and mitigate particles detachment during ion beam milling, enabling precise extraction of ultra-thin lamellae for (S)TEM characterization. Consequently, the feasibility of this FES-FIB process is verified by site-specific extraction of the cross-sectional lamellae from two typical structures: spherical microparticles and nanoflakes, successfully collecting the morphology and structural details by (S)TEM.

Gelidium species cultivation is rare because establishing one methodology is difficult, or even when this is possible, the application to the field can be a challenge. These difficulties are associated with the low growth rates related to the availability of nutrients in culture media. The goal of this study was to observe the role of extracellular calcium on spore germination. We investigated the effects of EGTA (a calcium-chelating agent) and CaCl₂ (a source of extracellular calcium) in the germination of Gelidium floridanum tetraspores. Tetraspores were cultivated with EGTA and CaCl for 6 h when the germ tube formation process was initiated. Adhesion, germination rate, and morphology analysis of the tetraspores were performed by light microscopy; analysis of actin filaments and cell wall (cellulose) by confocal scanning laser microscopy; and ultrastructure analysis by transmission electron microscopy (TEM). There was no germination of tetraspores, and adhesion was reduced when treated with EGTA. A higher germination rate and acceleration of this process was observed when treated with CaCl, indicating that germination and adhesion are calcium-dependent. Tetraspores treated with EGTA show no cell wall formation or polarization of actin filaments, confirmed by TEM, indicating interference with intracellular calcium homeostasis and disorganization of organelles. These results contrasted with those observed in CaCl treatment, where a small amount of extracellular calcium accelerates the germinative process. Based on these results, we conclude that this species has the germination dependent on extracellular Ca influx, and its suppression may cause the interruption of Ca-dependent signaling required for tetraspores germination.

A phase imaging method, Diffracted Beam Interferometry, has imaged a dislocation passing through a crystal specimen and annihilating on the bottom free surface. The strain associated with the dislocation and released at the free surface transforms the 1 dimensional dislocation to a three dimensional volume defect most likely a surface pit. A mechanism based on dislocation theory is proposed for the transformational process.

Elastic electron delocalization displaces elemental signals from their true atomic positions, introducing artifacts in atomic-resolution elemental maps acquired via atomic-resolution energy-dispersive X-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS), which may potentially lead to misinterpretation of new structure. This study systematically investigates the influence of the atomic coordination environment on delocalization distance using a model structure of multi-element metal carbide MoErNbAlC. Building on experimentally observed artifacts, model simulations reveal that EELS signals are more localized for light elements, while EDS signals are more localized for heavy elements. Furthermore, while the delocalization distance follows an increasing trend with larger convergence semi-angles and greater sample thicknesses, the atomic number of neighboring atoms has a negligible effect-typically resulting in deviations of less than 0.1 Å, which is negligible for current structural interpretation. In contrast, variations in interatomic spacing lead to non-monotonic changes in delocalization distance, with overall fluctuations remaining within 20 %, even as spacing nearly doubles. These insights offer a quantitative basis for identifying and interpreting imaging artifacts, contributing to more accurate atomic-scale structural analysis using EELS and EDS.

This study investigates the cellular immune responses of hemocytes against experimental targets (buffalo RBCs and yeast cells) in the freshwater crab Barytelphusa cunicularis. Total hemocyte count (THC), differential hemocyte count (DHC), viability of hemocytes using trypan blue exclusion test, inherent phagocytic ability and enhancement in phagocytic ability up on pre-treating with serum agglutinins was evaluated. The THC was determined to be 1.12 × 107 cells/ml. Further, transmission electron microscope (TEM) images showed three distinct cell types based on their morphological features and the presence of other cellular organelles. Additionally, the hemocyte count of B. cunicularis revealed 24 % hyaline cells with no granularity, 60 % semi-granular cells exhibiting variable cytoplasmic granularity and 16 % granular cells containing numerous large granules. Similarly, viability assays using trypan blue exclusion demonstrated a decline from 99 % to 92 % over a 120 min period. Moreover, the inherent phagocytic ability of hemocytes and enhancement in phagocytosis up on pre-treating with serum agglutinins was assessed using buffalo RBCs and yeast cells as targets. In addition, the inherent phagocytic ability was found to be 25 % and showed an enhancement to 39 % in buffalo RBCs for opsono-phagocytosis and for yeast cells it showed an enhancement from 26 % to 32 %. This study revealed the unusual occurrence of binucleate granulocyte devoid of nucleus. Understanding these cellular defense mechanisms contributes to elucidating the innate immunity of B. cunicularis.

To overcome the limitations in current identification techniques for non-bead freshwater cultured pearls(NFC), this study employed X-ray transmission imaging (RTX) and micro-computed tomography (μ-CT) to analyze the internal structures of 45 near-round or baroque NFC, aiming to reveal the correlation between their internal structural characteristics and cultivation origins. The experimental results demonstrate that void structures are universally present in the growth centers of NFC, which can be classified into five morphological types (tiny crack-like voids, tiny rod-like voids, multi-void complex, large crack-like voids, and large rod-like voids). Notably, larger voids were exclusively observed in baroque samples and showed structural similarities to non-bead saltwater cultured pearls ("keshi" pearls), suggesting their formation results from expelled nuclei during cultivation. In contrast, natural saltwater pearls predominantly exhibit compact structures with only 6 % showing central voids, presenting a distinct difference from NFC. While non-bead saltwater cultured pearls display void characteristics overlapping with some freshwater samples, their identification requires comprehensive analysis incorporating additional features. This study not only expands the structural database of NFC but also provides a scientific basis for reliable origin authentication.

Photosensitive materials are widely used in micro-/nanofabrication and photonic device development, where their refractive index (RI) distributions play a critical role in determining optical performances. To enable precise measurements of the RI distribution in photosensitive materials - particularly in the microstructures of photoresists - this study proposes a quantitative reconstruction method based on differential interference contrast (DIC) microscopy. Unlike conventional approaches requiring intermediate phase retrieval or interferometric systems, the proposed method directly reconstructs RI from intensity images acquired at multiple polarization angles and axial planes. A global optimization framework based on the first Born approximation enables high spatial resolution, rapid computation (∼30 s for images of 250 × 250 pixels), and high measurement accuracy. Experimental validation on periodic photoresist patterns shows a clear RI contrast between bleached and unbleached regions, with absolute relative errors of the RI reconstruction below 0.4% and mean absolute relative error of 0.17%. This technique offers a compact and efficient solution for quantitative RI characterization, with promising applicability in micro-/nanofabrication, photonic device inspection, and process monitoring.

We present the design and performance of a novel scanning tunnelling microscope (STM) that demonstrate compatibility with a cryogen-free superconducting magnet operation. The STM features an isolated scanning unit housing a tightly clamped piezoelectric tube scanner (PTS) and a zirconia shaft collectively forming the PTS unit supported by a zirconia frame. To minimize magnetic field interference, all components within the tip-sample mechanical loop are made of sapphire and zirconia. The PTS unit are clamped firmly to suppress vibrations induced by the magnet. For coarse approach, we employ an improved GeckoDrive motor capable of delivering an output force exceeding 2.2 N to actuate the tightly held PTS unit. After tunneling current detection, the tip-sample mechanical loop is mechanically decoupled from the piezo motor to suppress vibration transfer, while high-voltage signal interference is mitigated through proper shielding and grounding, ensuring stable imaging. The devices exceptional performance was validated through atomic-resolution imaging of graphite. The system demonstrates excellent stability, maintaining low drift rates in both the X-Y plane and Z direction at room and cryogenic temperatures, ensuring precise tip-sample alignment. Furthermore, we obtained atomic-resolution images of HOPG by varying the magnetic field from 0 T to 9 T at 300 K and acquired dI/dV spectra of an NbSe₂ sample at 3 K. These results indicated that our compact device is highly suitable for STM imaging and STS spectroscopy studies in high magnetic fields and low temperatures. Its high output force and stable performance make it well-suited for exploring magnetic field effects and low-temperature electronic properties in quantum and strongly correlated materials.

Laser powder bed fusion (LPBF) technology provides a new approach for microstructure control of high entropy alloys (HEAs) through layer-by-layer stacking and rapid solidification characteristics. This study focuses on the AlCoCrFeNi HEAs and systematically investigates the effects of different interlayer rotation angles (0°, 67°, 90°) on the porosity, grain orientation, phase distribution, and mechanical properties of LPBF formed HEAs. The results showed that the interlayer rotation angle significantly controlled the grain morphology and grain boundary characteristics by changing the thermal accumulation and gradient direction of the melt pool. At a rotation angle of 67°, the melt pool size increased, the porosity decreased to 2.05 %, and the proportion of high angle grain boundaries (HAGB) increased to 31.34 %. Combining EBSD and TEM analysis, it was found that at the rotation angle of 67°, the BCC phase content increased to 8.36 %, the preferred grain orientation weakened, the degree of recrystallization increased to 7.69 %, and the dislocation network density decreased to 1.18 × 10m. These promoted the tensile strength to 733.53 MPa, an increase of 36.9 % compared to the 0° sample and 6.4 % compared to the 90° sample. This study reveals the coupling mechanism of interlayer rotation angle on the 'thermal-mechanical-microstructure' of LPBF formed HEAs, providing theoretical support for the optimization of additive manufacturing processes for high-performance complex structural alloys.

Correlative microscopy has gained increasing importance across a range of research disciplines. Combining different microscopy techniques broadens knowledge about a sample by providing more comprehensive insights. In particular, the correlation of atomic force microscopy (AFM) and transmission electron microscopy (TEM) offers a powerful complementary approach for investigating materials, as both surface and subsurface information can be obtained. The fundamental motivation of this study is to establish a direct correlation between measurements obtained from the same specimen region by both methods. Such correlation is not always straightforward, as each technique requires different sample preparation. Consequently, performing AFM measurements on TEM samples inevitably gives rise to several challenges, including, but not limited to, surface distortion and limited accessibility. In this study, we propose a range of AFM measurement strategies tailored to two typical TEM sample types: a 3 nm thin membrane on lacey carbon and a TEM lamella mounted on a lift-out grid. We compare the influence of different cantilever dimensions and AFM modes on image quality, and explore the fabrication of AFM tips positioned at the very front of a cantilever via focused electron beam induced deposition to improve accessibility of regions of interest. With the strategies developed here, we successfully demonstrate the feasibility of AFM measurements on TEM samples without the need for additional sample preparation, enabling direct correlation. The results highlight the practical viability of this combined approach, and expand the scope of correlative microscopy for advanced materials characterization.