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Microscopy

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https://www.readbyqxmd.com/read/29992251/ultrafast-electron-microscopy-with-relativistic-femtosecond-electron-pulses
#1
Jinfeng Yang, Yoichi Yoshida, Hidehiro Yasuda
Ultrafast electron microscopy (UEM) with femtosecond temporal resolution is a 'dream machine' that has been long envisioned for the study of ultrafast structural dynamics in materials. For this purpose, we developed a prototype UEM with relativistic femtosecond electron pulses generated by a radio-frequency acceleration-based photoemission gun. TEM images of polystyrene latex particles and gold nanoparticles were observed using approximately 100-fs-long electron pulses with energies of 3.1 MeV. The effect of emittance and the number of pulses on the images were investigated...
July 9, 2018: Microscopy
https://www.readbyqxmd.com/read/29982618/low-voltage-sem-contrasts-of-steel-surface-studied-by-observations-and-electron-trajectory-simulations-for-gemini-lens-system
#2
Kohei Tandokoro, Masayasu Nagoshi, Takashi Kawano, Kaoru Sato, Katsushige Tsuno
Scanning electron microscopy (SEM) is a powerful tool for observing the surface of materials. Modern SEM systems have multiple detectors with different geometries. Consequently, the SEM image contrast depends on the instrument and experimental conditions even for the same sample. Understanding the SEM imaging mechanism is necessary to for clarify SEM contrast. In this paper, low-voltage (LV)-SEM image contrast is investigated by comparing LV-SEM images and electron trajectory simulation results. Surface observations of oxides on a steel surface, positive charging contrast and topographic contrast in the image systematically changed with the working distance (WD)...
July 6, 2018: Microscopy
https://www.readbyqxmd.com/read/29982733/illumination-semiangle-of-10-9-rad-achieved-in-a-1-2-mv-atomic-resolution-holography-transmission-electron-microscope
#3
Tetsuya Akashi, Yoshio Takahashi, Ken Harada, Toshio Onai, Yoshimasa A Ono, Hiroyuki Shinada, Yasukazu Murakami
The coherency of a 1.2-MV transmission electron microscope was evaluated through illumination semiangles calculated from lengths over which Fresnel fringes can be observed. These lengths were determined from the diameters of circular holes fully filled with Fresnel fringes, i.e. this method allows lengths to be accurately measured even if micrographs are subjected to distortions. The smallest illumination semiangle of 4.0 × 10-9 rad was obtained for a circular hole with a diameter of 191 μm. In addition, electron beam brightness was estimated to be approximately 3 × 1014 A/m2·sr from the obtained illumination semiangle values and current densities...
July 3, 2018: Microscopy
https://www.readbyqxmd.com/read/29931086/short-time-pretreatment-of-wood-with-low-concentration-and-room-temperature-ionic-liquid-for-sem-observation
#4
Taiji Yamashita, Kenji Miyamoto, Hitoshi Yonenobu
A new pretreatment method using room-temperature ionic liquid (IL) was proposed for observing wood specimens in scanning electron microscopy (SEM). A variety of concentrations were examined for ethanol solution of the IL, [Emim][MePO3Me], to determine an optimal pretreatment procedure. It was concluded that 10% ethanol solution of the IL was the most adequate to acquire good SEM images. Using the procedure optimized, SEM images were taken for typical anatomical types of modern soft and hardwood species and archeological wood...
June 20, 2018: Microscopy
https://www.readbyqxmd.com/read/29920601/backscattered-electron-imaging-of-resin-embedded-sections
#5
Daisuke Koga, Satoshi Kusumi, Tsuyoshi Watanabe
Scanning electron microscopes have longer focal depths than transmission electron microscopes and enable visualization of the three-dimensional (3D) surface structures of specimens. While scanning electron microscopy (SEM) in biological research was generally used for the analysis of bulk specimens until around the year 2000, more recent instrumental advances have broadened the application of SEM; for example, backscattered electron (BSE) signals under low accelerating voltages allow block-face and section-face images of tissues embedded in resin to be acquired...
June 15, 2018: Microscopy
https://www.readbyqxmd.com/read/29893959/development-of-a-three-dimensional-tomography-holder-for-in-situ-tensile-deformation-for-soft-materials
#6
Takeshi Higuchi, Takashi Gondo, Hiroya Miyazaki, Akemi Kumagai, Keizo Akutagawa, Hiroshi Jinnai
An in situ straining holder capable of tensile deformation and high-angle tilt for electron tomography was developed for polymeric materials. The holder has a dedicated sample cartridge, on which a variety of polymeric materials, such as microtomed thin sections of bulk specimens and solvent-cast thin films, can be mounted. Fine, stable control of the deformation process with nanoscale magnification was achieved. The holder allows large tensile deformation (≃800 μm) with a large field of view (800 × 200 μm before the deformation), and a high tilt angle (±75°) during in situ observations...
June 11, 2018: Microscopy
https://www.readbyqxmd.com/read/29846664/soft-x-ray-emission-spectroscopy-study-of-characteristic-bonding-states-and-its-distribution-of-amorphous-carbon-nitride-a-cnx-films
#7
Shingo Ishii, Masami Terauchi, Yohei Sato, Naoyuki Tamura, Masami Aono, Hiroshi Abe
Soft X-ray emission spectroscopy based on electron microscopy was applied to investigate bonding electron states of amorphous carbon nitride (a-CNx) films with different nitrogen contents of x. Carbon K-emission spectrum showed characteristic intensity distribution of not only sp2 bonding but also sp3 bonding. The a-CNx film with lager x, which has a larger macroscopic electric resistivity, shows a larger content of the carbon sp3: C-C bonding signal. Furthermore, the dependence of spectral intensity distribution on x suggests the presence of sp2: C-N and sp3: C-N bonding...
May 22, 2018: Microscopy
https://www.readbyqxmd.com/read/29788326/in-situ-transmission-electron-microscopic-observations-of-redox-cycling-of-a-ni-scsz-cermet-fuel-cell-anode
#8
Junko Matsuda, Tatsuya Kawasaki, Shotaro Futamura, Tsutomu Kawabata, Shunsuke Taniguchi, Kazunari Sasaki
In situ transmission electron microscopy (TEM) observations of a Ni(O)-Sc2O3-stabilized ZrO2 (ScSZ; 10 mol% Sc2O3, 1 mol% CeO2, 89 mol% ZrO2) anode in a solid oxide fuel cell (SOFC) have been performed at high temperatures under a hydrogen/oxygen gas atmosphere using an environmental transmission electron microscope (ETEM); the specimens were removed from cross-sections of the real SOFC by focused ion beam milling and lifting. When heating the NiO-ScSZ anode under a hydrogen atmosphere of 3 mbar in ETEM, nano-pores were formed at the grain boundaries and on the surface of NiO particles at around 400°C due to the volume shrinkage accompanying the reduction of NiO to Ni...
May 19, 2018: Microscopy
https://www.readbyqxmd.com/read/29771342/recent-progress-in-structural-biology-lessons-from-our-research-history
#9
Ryo Nitta, Tsuyoshi Imasaki, Eriko Nitta
The recent 'resolution revolution' in structural analyses of cryo-electron microscopy (cryo-EM) has drastically changed the research strategy for structural biology. In addition to X-ray crystallography and nuclear magnetic resonance spectroscopy, cryo-EM has achieved the structural analysis of biological molecules at near-atomic resolution, resulting in the Nobel Prize in Chemistry 2017. The effect of this revolution has spread within the biology and medical science fields affecting everything from basic research to pharmaceutical development by visualizing atomic structure...
May 16, 2018: Microscopy
https://www.readbyqxmd.com/read/29762753/annular-dark-field-scanning-confocal-electron-microscopy-studied-using-multislice-simulations
#10
Takumi Hamaoka, Chih-Yu Jao, Masaki Takeguchi
Annular dark-field scanning confocal electron microscopy (ADF-SCEM) has been studied using multislice simulations. Thermal diffuse scattering was considered in the calculations. Geometric aberrations of the lenses were introduced. A finite-sized pinhole was taken into consideration, in addition to an ideal point pinhole. ADF-SCEM images of Al crystals aligned along a zone-axis exhibit elongated contrast along the optic axis. Results of simulations suggest that if geometric aberrations of an imaging lens are corrected, depth resolution in ADF-SCEM can be improved by employing a large collection semi-angle of an annular aperture, even with a finite pinhole...
May 14, 2018: Microscopy
https://www.readbyqxmd.com/read/29750255/investigation-of-cell-cycle-associated-structural-reorganization-in-nucleolar-fc-dfcs-from-mouse-mfc-cells-by-electron-microscopy
#11
Lingling Chen, Yang Jiao, Xin Guan, Xiliang Li, Yunpeng Feng, Mingda Jiao
Nucleolus structure alters as the cell cycle is progressing. It is established in telophase, maintained throughout the entire interphase and disassembled in metaphase. Fibrillar centers (FCs), dense fibrillar components (DFCs) and granular components (GCs) are essential nucleolar organizations where rRNA transcription and processing and ribosome assembly take place. Hitherto, little is known about the cell cycle-dependent reorganization of these structures. In this study, we followed the nucleolus structure during the cell cycle by electron microscopy (EM)...
May 1, 2018: Microscopy
https://www.readbyqxmd.com/read/29741637/microscopic-analysis-of-sperm-movement-links-to-mechanisms-and-protein-components
#12
Kazuo Inaba, Kogiku Shiba
Cilia and flagella are cell machines that power hydrodynamic forces by fast beating. They are composed of bundles of 9 + 2 microtubules that associate with several protein structures including axonemal dyneins and their regulators. Spermatozoa are single cells with in most cases a single flagellum and are good cell models to study how flagellar movements are regulated and linked to cell behavior. In addition, the assessment of sperm motility is an important diagnostic tool for evaluating male fertility in human reproductive medicine, and in livestock and fisheries sciences...
June 1, 2018: Microscopy
https://www.readbyqxmd.com/read/29635636/electric-shielding-films-for-biased-tem-samples-and-their-application-to-in-situ-electron-holography
#13
Yuki Nomura, Kazuo Yamamoto, Tsukasa Hirayama, Koh Saitoh
We developed a novel sample preparation method for transmission electron microscopy (TEM) to suppress superfluous electric fields leaked from biased TEM samples. In this method, a thin TEM sample is first coated with an insulating amorphous aluminum oxide (AlOx) film with a thickness of about 20 nm. Then, the sample is coated with a conductive amorphous carbon film with a thickness of about 10 nm, and the film is grounded. This technique was applied to a model sample of a metal electrode/Li-ion-conductive-solid-electrolyte/metal electrode for biasing electron holography...
June 1, 2018: Microscopy
https://www.readbyqxmd.com/read/29590408/phase-retrieval-using-through-focus-images-in-lorentz-transmission-electron-microscopy
#14
Takahiro Tamura, Yukinori Nakane, Hiroshi Nakajima, Shigeo Mori, Ken Harada, Yoshizo Takai
In this study, we report on phase retrieval by the maximum likelihood method with conjugate gradient method (CG-MAL) using through-focus images in Lorentz transmission electron microscopy (LTEM). The method was evaluated using 32 simulated and experimentally obtained through-focus images of magnetic bubbles; these images were collected under a defocus range from approximately -3 mm to 3 mm. Consequently, we obtained the magnetic domain structures of the magnetic bubbles in both the simulation and the LTEM experiment...
June 1, 2018: Microscopy
https://www.readbyqxmd.com/read/29554288/ti-workbench-an-integrated-software-package-for-electrophysiology-and-imaging
#15
Takafumi Inoue
TI Workbench is a software package that serves as a control and analysis center for cellular imaging and electrophysiological experiments. It is unique among general-purpose software packages where it integrates the control of cellular imaging and electrophysiological devices, as well as sophisticated data analyses, which provides superior usability in imaging experiments combined with electrophysiology. During the development over the last 20 years, the range of supported image acquisition devices has expanded from cooled charge-coupled device (CCD) cameras to multi-photon microscope systems...
June 1, 2018: Microscopy
https://www.readbyqxmd.com/read/29509921/microstructural-observation-of-casein-micelles-in-milk-by-cryo-electron-microscopy-of-vitreous-sections-cemovis
#16
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...
June 1, 2018: Microscopy
https://www.readbyqxmd.com/read/29474670/evaluation-of-residual-aberration-in-fifth-order-geometrical-aberration-correctors
#17
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...
June 1, 2018: Microscopy
https://www.readbyqxmd.com/read/29701816/electron-diffraction-covering-a-wide-angular-range-from-bragg-diffraction-to-small-angle-diffraction
#18
Hiroshi Nakajima, Atsuhiro Kotani, Ken Harada, Shigeo Mori
We construct an electron optical system to investigate Bragg diffraction (the crystal lattice plane, 10-2 to 10-3 rad) with the objective lens turned off by adjusting the current in the intermediate lenses. A crossover was located on the selected-area aperture plane. Thus, the dark-field imaging can be performed by using a selected-area aperture to select Bragg diffraction spots. The camera length can be controlled in the range of 0.8-4 m without exciting the objective lens. Furthermore, we can observe the magnetic-field dependence of electron diffraction using the objective lens under weak excitation conditions...
April 9, 2018: Microscopy
https://www.readbyqxmd.com/read/29635467/role-of-medical-ozone-in-attenuating-age-related-changes-in-the-rat-cerebellum
#19
Wael B Elkholy, Marwa A Al-Gholam
Aging is an inevitable biological process characterized by motor in coordination and decline in the ability to learn new motor skills. The purpose of this study is to investigate, for the first time, the beneficial antiaging effects of medical ozone (O3) on the age-related structural damage of the rat cerebellum. We have examined the cerebellum of albino rats at the ages of 6, 20 and 22, and the effect of intraperitoneal medical O3 administration (0.7 g/kg) by histological, immunohistochemical and morphometric studies...
April 9, 2018: Microscopy
https://www.readbyqxmd.com/read/29474725/thermal-stability-of-laser-induced-modified-volumes-in-si-as-studied-by-in-situ-and-ex-situ-heating-experiments
#20
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.
April 1, 2018: Microscopy
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