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Takamichi Kamigaki, Yosiko Ito, Yuri Nishino, Atsuo Miyazawa
Casein micelles are present in bovine milk as colloidal particles with diameters of 20-600 nm, which are complex macromolecular assemblies composed of four distinct types of casein and colloidal calcium phosphate (CCP). Multiple structural models of casein micelles have been proposed based on their biochemical or physical properties and observed using electron microscopy. However, the CCP distribution and crosslinking structure between CCP and casein remain unclear. Therefore, the internal structure of casein micelles in raw milk was observed using cryo-electron microscopy of vitreous sections (CEMOVIS) with high precision at high resolution...
March 2, 2018: Microscopy
Hiroyasu Saka, Hiroyuki Iwata, Daisuke Kawaguchi
Radiation of a permeable laser beam into Si induces considerable modification of structures. Thermal stability of the laser-induced modified volumes (LIMV's) was studied comprehensively by means of in situ and ex situ heating experiments using transmission electron microscopy. The behavior in the tail region of a LIMV can be understood by dislocation theory, while that of a void formed at the very focus of a laser beam cannot be understood easily.
February 21, 2018: Microscopy
Shigeyuki Morishita, Yuji Kohno, Fumio Hosokawa, Kazu Suenaga, Hidetaka Sawada
Higher order geometrical aberration correctors for transmission electron microscopes are essential for atomic-resolution imaging, especially at low-accelerating voltages. We quantitatively calculated the residual aberrations of fifth-order aberration correctors to determine the dominant aberrations. The calculations showed that the sixth-order three-lobe aberration was dominant when fifth-order aberrations were corrected by using the double-hexapole or delta types of aberration correctors. It was also deduced that the sixth-order three-lobe aberration was generally smaller in the delta corrector than in the double-hexapole corrector...
February 21, 2018: Microscopy
Hideaki Nakayama, Norio Kitagawa, Takahito Otani, Hiroshi Iida, Hisashi Anan, Tetsuichiro Inai
Intestinal epithelial cells are the first targets of ingested mycotoxins, such as ochratoxin A, citrinin and deoxynivalenol. It has been reported that paracellular permeability regulated by tight junctions is modulated by several mycotoxins by reducing the expression of specific claudins and integral membrane proteins in cell-cell contacts, accompanied by increase in phosphorylation of mitogen-activated protein kinases, including extracellular signal-related kinase (ERK) 1/2, p38 and c-Jun NH2-terminal protein kinase...
February 21, 2018: Microscopy
Tatsuki Tahara, Xiangyu Quan, Reo Otani, Yasuhiro Takaki, Osamu Matoba
In this review, we introduce digital holographic techniques and recent progress in multidimensional sensing by using digital holography. Digital holography is an interferometric imaging technique that does not require an imaging lens and can be used to perform simultaneous imaging of multidimensional information, such as three-dimensional structure, dynamics, quantitative phase, multiple wavelengths and polarization state of light. The technique can also obtain a holographic image of nonlinear light and a three-dimensional image of incoherent light with a single-shot exposure...
February 17, 2018: Microscopy
Tobias Heil, Gordon J Tatlock
This publication is a systematic investigation of the effect the improvement of dark-reference images has on the resulting bright-field images. For this, data were acquired with three different charge-coupled device cameras attached to two different transmission electron microscopes. Multi-frame acquisitions and methods to correct x-ray noise are introduced and quantified as options to improve the dark-reference images. Furthermore, the influence of x-ray noise on transmission electron microscopy measurements is discussed and observations on its composition are shared...
February 13, 2018: Microscopy
Tetsuichi Wazawa, Yoshiyuki Arai, Yoshinobu Kawahara, Hiroki Takauchi, Takashi Washio, Takeharu Nagai
Far-field super-resolution fluorescence microscopy has enabled us to visualize live cells in great detail and with an unprecedented resolution. However, the techniques developed thus far have required high-power illumination (102-106 W/cm2), which leads to considerable phototoxicity to live cells and hampers time-lapse observation of the cells. In this study we show a highly biocompatible super-resolution microscopy technique that requires a very low-power illumination. The present technique combines a fast photoswitchable fluorescent protein, Kohinoor, with SPoD-ExPAN (super-resolution by polarization demodulation/excitation polarization angle narrowing)...
February 2, 2018: Microscopy
Kartik Venkatraman, Peter Rez, Katia March, Peter A Crozier
High-resolution monochromated electron energy-loss spectroscopy has the potential to map vibrational modes at nanometer resolution. Using the SiO2/Si interface as a test case, we observe an initial drop in the SiO2 vibrational signal when the electron probe is 200 nm from the Si due to long-range nature of the Coulomb interaction. However, the distance from the interface at which the SiO2 integrated signal intensity drops to half its maximum value is 5 nm. We show that nanometer resolution is possible when selecting the SiO2/Si interface signal which is at a different energy position than the bulk signal...
February 1, 2018: Microscopy
Yi Wang, Y Eren Suyolcu, Ute Salzberger, Kersten Hahn, Vesna Srot, Wilfried Sigle, Peter A van Aken
Specimen and stage drift as well as scan distortions can lead to a mismatch between true and desired electron probe positions in scanning transmission electron microscopy (STEM) which can result in both linear and nonlinear distortions in the subsequent experimental images. This problem is intensified in STEM spectrum and diffraction imaging techniques owing to the extended dwell times (pixel exposure time) as compared to conventional STEM imaging. As a consequence, these image distortions become more severe in STEM spectrum/diffraction imaging...
January 29, 2018: Microscopy
Shigeto Isakozawa, Taishi Fuse, Junpei Amano, Norio Baba
As alternatives to the diffractogram-based method in high-resolution transmission electron microscopy, a spot auto-focusing (AF) method and a spot auto-stigmation (AS) method are presented with a unique high-definition auto-correlation function (HD-ACF). The HD-ACF clearly resolves the ACF central peak region in small amorphous-thin-film images, reflecting the phase contrast transfer function. At a 300-k magnification for a 120-kV transmission electron microscope, the smallest areas used are 64 × 64 pixels (~3 nm2) for the AF and 256 × 256 pixels for the AS...
January 25, 2018: Microscopy
Yasuko Kaneko, Makoto Tokunaga, Kyoko Tanaka, Kimie Atsuzawa, Masako Nishimura
Rapidly frozen rosemary leaves were observed at variable accelerating voltages in a low-vacuum scanning electron microscope equipped with a cryo transfer system. After water was sublimated from the fractured face of the leaf, distinct backscattered electron (BSE) images were obtained depending on the accelerating voltages applied. At 5 kV, surface cell wall structure was observed, whereas at 10 and 15 kV chloroplasts lining the inside of the cell wall and membrane were visualized. With energy dispersive X-ray microanalysis, elemental information corresponding to the BSE images was obtained...
January 24, 2018: Microscopy
Maureen J Lagos, Andreas Trügler, Voshadhi Amarasinghe, Leonard C Feldman, Ulrich Hohenester, Philip E Batson
Using spatially resolved Electron Energy-Loss Spectroscopy, we investigate the excitation of long-wavelength surface optical vibrational modes in elementary types of nanostructures: an amorphous SiO2 slab, an MgO cube, and in the composite cube/slab system. We find rich sets of optical vibrational modes strongly constrained by the nanoscale size and geometry. For slabs, we find two surface resonances resulting from the excitation of surface phonon polariton modes. For cubes, we obtain three main highly localized corner, edge, and face resonances...
January 23, 2018: Microscopy
S Löffler, W Hetaba
Energy-loss magnetic chiral dichroism (EMCD) is a versatile method for studying magnetic properties on the nanoscale. However, the classical EMCD technique is notorious for its low signal-to-noise ratio (SNR), which is why many experimentalists have adopted a convergent-beam approach. Here, we study the theoretical possibilities of using a convergent beam for EMCD. In particular, we study the influence of detector positioning as well as convergence and collection angles on the detectable EMCD signal. In addition, we analyse the expected SNR and give some guidelines for achieving optimal EMCD results...
January 23, 2018: Microscopy
Masami Terauchi, Haruhiko Morito, Hisanori Yamane, Shogo Koshiya, Koji Kimoto
Chemical bonding state of sodium borosilicide Na8B74.5Si17.5, which is a new member of B12-cluster materials, is investigated by soft X-ray emission spectroscopy. The material is composed of B12 cluster network and characteristic silicon chains of [-Si-(Si-Si)3-Si-] connected by sp3 bonding, in which bonding distances and bonding angles are close to those in cubic Si crystal. B K-emission spectrum of the material showed a similar but a broader intensity distribution with those of B12 cluster materials of α-r-B, B4C and β-r-B...
January 23, 2018: Microscopy
Hideyuki Magara, Takeshi Tomita, Yukihito Kondo, Takafumi Sato, Zentaro Akase, Daisuke Shindo
A secondary electron (SE) energy analyzer was developed for a transmission electron microscope. The analyzer comprises a microchannel plate (MCP) for detecting electrons, a coil for collecting SEs emitted from the specimen, a tube for reducing the number of backscattered electrons incident on the MCP, and a retarding mesh for selecting the energy of SEs incident on the MCP. The detection of the SEs associated with charging phenomena around a charged specimen was attempted by performing electron holography and SE spectroscopy using the energy analyzer...
January 23, 2018: Microscopy
Toshihide Agemura, Takashi Sekiguchi
Collection efficiency and acceptance maps of typical detectors in modern scanning electron microscopes (SEMs) were investigated. Secondary and backscattered electron trajectories from a specimen to through-the-lens and under-the-lens detectors placed on an electron optical axis and an Everhart-Thornley detector mounted on a specimen chamber were simulated three-dimensionally. The acceptance maps were drawn as the relationship between the energy and angle of collected electrons under different working distances...
January 11, 2018: Microscopy
Youhei Egami, Nobukazu Araki
M-Ras, a member of the Ras superfamily, is known to be involved in diverse cellular processes. However, its involvement in FcγR-mediated phagocytosis remains unknown. We examined the spatiotemporal localization of M-Ras during the engulfment of IgG-opsonized erythrocytes (IgG-Es) in RAW264 macrophages. By the live-cell imaging of fluorescent protein-fused M-Ras, we found that M-Ras was localized to the membrane of phagocytic cups during the early stage of phagosome formation. Notably, ratiometric image analysis revealed that M-Ras was concentrated in the membrane of forming phagosomes...
January 11, 2018: Microscopy
Lewys Jones, Aakash Varambhia, Richard Beanland, Demie Kepaptsoglou, Ian Griffiths, Akimitsu Ishizuka, Feridoon Azough, Robert Freer, Kazuo Ishizuka, David Cherns, Quentin M Ramasse, Sergio Lozano-Perez, Peter D Nellist
As an instrument, the scanning transmission electron microscope is unique in being able to simultaneously explore both local structural and chemical variations in materials at the atomic scale. This is made possible as both types of data are acquired serially, originating simultaneously from sample interactions with a sharply focused electron probe. Unfortunately, such scanned data can be distorted by environmental factors, though recently fast-scanned multi-frame imaging approaches have been shown to mitigate these effects...
January 11, 2018: Microscopy
Hiroyuki Iwata, Daisuke Kawaguchi, Hiroyasu Saka
Internal modification induced in Si by a permeable pulse laser was investigated by transmission electron microscopy. A laser induced modified volume (LIMV) was a cylindrical rod along the track of a laser beam with the head at the focus of the laser beam. In the LIMV, beside voids, dislocations, micro-cracks and what had been supposed to be an unidentified high-pressure phase (hpp) of Si were observed in LIMV. The so-called 'hpp' was identified mostly as diamond Si.
January 6, 2018: Microscopy
Takahiro Tamura, Yoshihide Kimura, Yoshizo Takai
In this study, a function for the correction of coma aberration, 3-fold astigmatism and real-time correction of 2-fold astigmatism was newly incorporated into a recently developed real-time wave field reconstruction TEM system. The aberration correction function was developed by modifying the image-processing software previously designed for auto focus tracking, as described in the first article of this series. Using the newly developed system, the coma aberration and 3-fold astigmatism were corrected using the aberration coefficients obtained experimentally before the processing was carried out...
January 5, 2018: Microscopy
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