Microscopy (Oxford, England)最新文献

(Scanning) transmission electron microscopy (TEM) images of samples in gas and liquid media are acquired with an environmental cell (EC) via silicon nitride membranes. The ratio of sample signal against the background is a significant factor for resolution. Depth-sectioning scanning TEM (STEM) is a promising technique that enhances the signal for a sample embedded in a matrix. It can increase the resolution to the atomic level, thereby enabling EC-STEM applications in important areas. This review introduces depth-sectioning STEM and its applications to high-resolution EC-STEM imaging of samples in gases and in liquids.

During the in situ transmission electron microscopy (TEM) observations, the diverse functionalities of different specimen holders play a crucial role. We hereby provide a comprehensive overview of the main types of holders, associated technologies and case studies pertaining to the widely employed heating and gas heating methods, from their initial developments to the latest advancement. In addition to the conventional approaches, we also discuss the emergence of holders that incorporate a micro-electro-mechanical system (MEMS) chip for in situ observations. The MEMS technology offers a multitude of functions within a single chip, thereby enhancing the capabilities and versatility of the holders. MEMS chips have been utilized in environmental-cell designs, enabling customized fabrication of diverse shapes. This innovation has facilitated their application in conducting in situ observations within gas and liquid environments, particularly in the investigation of catalytic and battery reactions. We summarize recent noteworthy studies conducted using in situ liquid TEM. These studies highlight significant advancements and provide valuable insights into the utilization of MEMS chips in environmental-cells, as well as the expanding capabilities of in situ liquid TEM in various research domains.

We developed an in-situ shear test system suitable for transmission electron microscopy (TEM) observations, which enabled us to examine the shear deformation behaviours inside soft materials at nanoscale resolutions. This study was conducted on a nanoparticle-filled rubber to investigate its nanoscale deformation behaviour under a large shear strain. First, the shear deformation process of a large area in the specimen was accurately examined and proven to exhibit an almost perfect simple shear. At the nanoscale, voids grew along the maximum principal strain during shear deformation. In addition, the nanoscale regions with rubber and silica aggregates exhibited deformation behaviours similar to the global shear deformation of the specimen. Although the silica aggregates exhibited displacement along the shearing directions, rotational motions were also observed owing to the torque generated by the local shear stress. This in-situ shear deformation system for TEM enabled us to understand the nanoscale origins of the mechanical properties of soft materials, particularly polymer composites. Graphical Abstract.

Solid-state batteries have potential to realize a rechargeable Li-metal anode. However, several challenges persist in the charging and discharging processes of the Li-metal anode, which require a fundamental understanding of Li plating and stripping across the interface of solid-state electrolytes (SEs) to address. This review overviews studies on Li-metal anodes in solid-state batteries using in situ observation techniques with an emphasis on Li electrodeposition and dissolution using scanning electron microscopy and SEs such as lithium phosphorus oxynitride and garnet-type compounds such as Li7La3Zr2O12. The previous research is categorized into three topics: (i) Li nucleation, growth and dissolution at the anode-free interface, (ii) electrochemical reduction of SE and (iii) short-circuit phenomena in SE. The current trends of each topic are summarized.

Glucose is the most important energy source in all organisms; however, our understanding of the pathways and mechanisms underlying glucose transportation and localization in living cells is incomplete. Here, we prepared two glucose analogs labeled with a dansylamino group at the C-1 (1-Dansyl) or C-2 (2-Dansyl) position; the dansyl group is a highly fluorescent moiety that is characterized by a large Stokes shift between its excitation and emission wavelengths. We then examined the cytotoxicity of the two glucose analogs in mammalian fibroblast cells and in the ciliated protozoan Tetrahymena thermophila. In both cell types, 2-Dansyl had no negative effects on cell growth. The specificity of cellular uptake of glucose analogs was confirmed using an inhibitor of glucose transporter in NIH3T3 cells. In NIH3T3 cells and T. thermophila, fluorescence microscopy revealed that the glucose analogs localized throughout the cytoplasm, but especially at the periphery of the nucleus. In T. thermophila, we also found that swimming speed was comparable in media containing non-labeled glucose or one of the glucose analogs, which provided more evidence not only that the analogs were not cytotoxic in these cells but also that the analogs had no negative effect on the ciliary motion. Together, the present results suggest that the glucose analogs have low toxicity and will be useful for bioimaging of glucose-related systems.

Perovskite oxides, ABO3, are potential catalysts for the oxygen evolution reaction, which is important in the production of hydrogen as a sustainable energy resource. Optimizing the chemical composition of such oxides by substitution or doping with additional elements is an effective approach to improving the activity of such catalysts. Here, we characterized the crystal and electronic structures of fluorine-doped La0.5Sr0.5CoO3-δ particles using scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). High-resolution STEM imaging demonstrated the formation of a disordered surface phase caused by fluorine doping. In addition, spatially resolved EELS data showed that fluorine anions were introduced into the interiors of the particles and that Co ions near the surfaces were slightly reduced by fluorine doping in conjunction with the loss of oxygen ions. Peak fitting of energy-loss near-edge structure data demonstrated an unexpected nanostructure in the vicinity of the surface. An EELS characterization comprising elemental mapping together with an energy-loss near-edge structure analysis indicated that this nanostructure could not be assigned to Co-based materials but rather to the solid electrolyte BaF2. Complementary structural and electronic characterizations using STEM and EELS as demonstrated herein evidently have the potential to play an increasingly important role in elucidating the nanostructures of functional materials.

Nanosized precipitates play a critical role in increasing the strength of metallic alloys. There are many reports that the initial precipitates are metastable phases holding a different composition and crystal structure from the equilibrium precipitate. The metastable precipitate transforms to its stable phase during heat treatment. A transmission electron microscope enables researchers to study the phase transition of metastable precipitates to stable phases due to its fine resolution in identifying crystal structures and chemical compositions. This review introduces the various phase transformation mechanisms of metastable precipitates to stable phases obtained from the analysis using a transmission electron microscope. The role of dislocation movement in the phase transition is further discussed.

We have demonstrated a new data analysis method that enables nondestructive depth profiling of a multilayer thin-film sample from energy-dispersive X-ray spectroscopy (EDX) data without the assumption of initial profiles. This method is based on a quadratic programming problem and allows for three-dimensional elemental mapping in the sample without destroying it, by performing depth profiling for all the pixels in the EDX two-dimensional mapping data. In this paper, first nondestructive depth profiling of two samples with different multilayer structures was performed using the proposed method. The results were compared with those obtained by cross-sectional observation to validate the accuracy and usefulness of the proposed method. Next, an example of the three-dimensional elemental mapping based on the proposed method was demonstrated. This method allows us to nondestructively obtain three-dimensional elemental distribution within a sample over a wide area on the order of mm, which is impossible to obtain using other analytical methods. The way to determine the hyperparameters, which significantly affects the calculation results, is fully described in this paper.

Optical errors, including spherical aberrations, hinder high-resolution imaging of biological samples due to biochemical components and physical properties. We developed the Deep-C microscope system to achieve aberration-free images, employing a motorized correction collar and contrast-based calculations. However, current contrast-maximization techniques, such as the Brenner gradient method, inadequately assess specific frequency bands. The Peak-C method addresses this issue, but its arbitrary neighbor selection and susceptibility to the noise limit its effectiveness. In this paper, we emphasize the importance of a broad spatial frequency range for accurate spherical aberration correction and propose Peak-F. This spatial frequency-based system utilizes a fast Fourier transform as a bandpass filter. This approach overcomes Peak-C's limitations and comprehensively covers the low-frequency domain of image spatial frequencies.

High-speed atomic force microscopy (HS-AFM) is now a widely used technique to study the dynamics of single biomolecules and complex structures. In the past, it has mainly been used to capture surface topography as structural analysis, leading to important discoveries not attainable by other methods. Similar to conventional AFM, the scope of HS-AFM was recently expanded to encompass quantities beyond topography, such as the measurement of mechanical properties. This review delves into various methodologies for assessing mechanical properties, ranging from semi-quantitative approaches to precise force measurements and their corresponding sample responses. We will focus on the application to single proteins such as bridging integrator-1, ion channels such as Piezo1, complex structures such as microtubules and supramolecular fibers. In all these examples, the unique combination of quantifiable force application and high spatiotemporal resolution allows to unravel mechanisms that cannot be investigated by conventional means.