Evidence of chlorite weathering to halloysite appears to be limited. Trioctahedral ferruginous chlorite occurring in granitic rocks and in situ altered phases isolated from the horizons of two soils in southern Korea were studied by scanning and transmission electron microscope (SEM, TEM), chemical, and X-ray diffraction (XRD) techniques to determine the mechanism of alteration and nature of alteration products. Chlorites were entirely converted to halloysite, kaolinite, and Fe-oxyhydroxides in the thick Bt horizon. In the E and BC horizons, in addition to 1:1 silicate clays and Fe-oxyhydroxides, chlorite-like and intergradient vermiculite-kaolin minerals were also found. Total chemical analysis of chlorite flakes revealed losses of substantial amounts of Fe and Mg. Large parallel sets of galleries suggested extensive exfoliation and expansion of chlorite flakes. Tubular halloysite formed bridges between the walls of galleries. The SEM and TEM analyses showed very distinct coatings (0.2–0.3 μm thick) of Fe-oxyhydroxides above and below the surface of galleries that consisted of rounded, sub-rounded, elongated, ultramicrocrystalline particles (goethite and hematite). The 1:1 mineral species found in the thick Bt horizon had a tubular and crumpled lamellar morphology. The presence of Fe likely creates a misfit between tetrahedral and octahedral sheets and results in the morphology of the 1:1 clays observed under SEM and TEM. The presence of intergradient minerals between chlorite and 1:1-type clays in the surface and transitional BC horizon suggests that, in addition to losses of OH sheet -Fe and -Mg, the chlorite with mostly Al-octahedra is partly transformed to double 1:1 silicate clays and intergradient minerals.

Transmission electron microscopy (TEM) has been used to demonstrate the biological formation of a hollow spherical halloysite-like mineral in freshwater systems. The interaction between clays and microbes was investigated in microbial films from laboratory cultures derived from natural sediments. Optical and electron microscopic observations of cultured microbes revealed that thin clay films covered areas of the bacterial cell wall. X-ray diffraction of the thin films after 2 y of ageing showed a 7.13 Å d spacing, consistent with a 7 Å halloysite-like phase [Al2Si2O5(OH)4 H2O]. Fourier transform infrared analysis of the thin film exhibited the characteristic adsorption bands for O−H (3651 cm−1), C−H and C−N (2925, 1454 and 1420 cm−1, respectively), suggesting that the phase was closely associated with adhesive organics. Observation by TEM of the thin films revealed that spherical, hollow, halloysite-like material formed on both coccus- and bacillus-type bacterial cells. Electron diffraction analysis of this material showed 2.9, 2.5, 2.2 and 1.5 Å d spacings. The present investigation strongly suggests that the thin film wall of the spherical halloysite-like material was associated with bacteria as a bio-organic product. This material, referred to hereafter as bio-halloysite, is further evidence for the microbially-mediated formation of clay minerals. The identity of the bacteria responsible for bio-halloysite formation is unknown, but is tentatively assigned to sulfate-reducing bacteria on the basis of morphology and the presence of reducing conditions in the microcosm at the end of the experiments.

The advent of modern, high-speed electron detectors has made the collection of multidimensional hyperspectral transmission electron microscopy datasets, such as 4D-STEM, a routine. However, many microscopists find such experiments daunting since analysis, collection, long-term storage, and networking of such datasets remain challenging. Some common issues are their large and unwieldy size that often are several gigabytes, non-standardized data analysis routines, and a lack of clarity about the computing and network resources needed to utilize the electron microscope. The existing computing and networking bottlenecks introduce significant penalties in each step of these experiments, and thus, real-time analysis-driven automated experimentation for multidimensional TEM is challenging. One solution is to integrate microscopy with edge computing, where moderately powerful computational hardware performs the preliminary analysis before handing off the heavier computation to high-performance computing (HPC) systems. Here we trace the roots of computation in modern electron microscopy, demonstrate deep learning experiments running on an edge system, and discuss the networking requirements for tying together microscopes, edge computers, and HPC systems.

In insects, the number, cytological and histological structures, and the spherocrystals of the Malpighian tubules (MTs) can vary considerably in different insect groups. These differences are considered important because they can be used as taxonomic characters. For this purpose, the ultrastructure of the MT epithelial cells in Leptophyes albovittata (Kollar, 1833) (Orthoptera, Tettigoniidae) was examined by light microscopy, scanning electron microscopy, and transmission electron microscopy. The wall of each tubule consists of a single layer of cells. These cells have round-shaped nuclei. Two different cell types were demonstrated in the tubule cell. These are cells that have electron-dense cytoplasm and electron-lucent cytoplasm. It was observed that the cytoplasm of these cells has many spherocrystals. The chemical composition of the spherocrystals was found to be high in carbon, phosphorus, and manganese in tubule cells.

The Online Electron Microscopy Platform makes electron microscopy education accessible by combining simulation-based practice with a range of educational content. Students learn how to operate electron microscopes by using virtual microscopes that precisely simulate the functions of real microscopes. Built as a web application, the platform can be used by an unlimited number of people and at any time. This platform reduces the time needed for training users to operate a real microscope. By preparing students in STEM disciplines to use electron microscopes, the system helps them acquire the skills they need to succeed in the modern workforce.

The transmission electron microscope is now used in a great variety of mineralogical and petrological contexts, The development of such applications over the past thirty years is illustrated by reference mainly to studies on serpentine and amphibole minerals.

The aberration-corrected scanning transmission electron microscope can provide information on nanostructures with sub-Ångström image resolution. The relatively intuitive interpretation of high-angle annular dark-field (HAADF) imaging technique makes it a popular tool to image a variety of samples and finds broad applications to characterizing nanostructures, especially when combined with electron energy-loss spectroscopy and X-ray energy-dispersive spectroscopy techniques. To quantitatively interpret HAADF images, however, requires full understanding of the various types of signals that contribute to the HAADF image contrast. We have observed significant intensity enhancement in HAADF images, and large expansion of lattice spacings, of surface atoms of atomically flat ZnO surfaces. The surface-resonance channeling effect, one of the electron-beam channeling phenomena in crystalline nanostructures, was invoked to explain the observed image intensity enhancement. A better understanding of the effect of electron beam channeling along surfaces or interfaces on HAADF image contrast may have implications for quantifying HAADF images and may provide new routes to utilize the channeling phenomenon to study surface structures with sub-Ångström spatial resolution.

Experimental low-loss electron (LLE) yields were measured as a function of loss energy for a range of elemental standards using a high-vacuum scanning electron microscope operating at 5 keV primary beam energy with losses from 0 to 1 keV. The resulting LLE yield curves were compared with Monte Carlo simulations of the LLE yield in the particular beam/sample/detector geometry employed in the experiment to investigate the possibility of modeling the LLE yield for a series of elements. Monte Carlo simulations were performed using both the Joy and Luo [Joy, D.C. & Luo, S., Scanning11(4), 176–180 (1989)] expression for the electron stopping power and recent tabulated values of Tanuma et al. [Tanuma, S. et al., Surf Interf Anal37(11), 978–988 (2005)] to assess the influence of the more recent stopping power data on the simulation results. Further simulations have been conducted to explore the influence of sample/detector geometry on the LLE signal in the case of layered samples consisting of a thin C overlayer on an elemental substrate. Experimental LLE data were collected from a range of elemental samples coated with a thin C overlayer, and comparisons with Monte Carlo simulations were used to establish the overlayer thickness.