Hatsujiro Hashimoto – A colourful and internationally revered electron microscopist

2017 ◽  
Vol 182 ◽  
pp. A1-A4 ◽  
Author(s):  
Archie Howie
Keyword(s):  
Electron Microscopist

Electron microscopy in diagnostic virology

1984 ◽  
Vol 42 ◽  
pp. 70-73
Author(s):  
S. E. Miller
Keyword(s):  
Electron Microscopy ◽  
Tissue Culture ◽  
Molecular Identification ◽  
Point Of View ◽  
Negative Stain ◽  
Viral Diagnosis ◽  
Electron Microscopist ◽  
Diagnostic Virology

The techniques for detecting viruses are many and varied including FAT, ELISA, SPIRA, RPHA, SRH, TIA, ID, IEOP, GC (1); CF, CIE (2); Tzanck (3); EM, IEM (4); and molecular identification (5). This paper will deal with viral diagnosis by electron microscopy and will be organized from the point of view of the electron microscopist who is asked to look for an unknown agent--a consideration of the specimen and possible agents rather than from a virologist's view of comparing all the different viruses. The first step is to ascertain the specimen source and select the method of preparation, e. g. negative stain or embedment, and whether the sample should be precleared by centrifugation, concentrated, or inoculated into tissue culture. Also, knowing the type of specimen and patient symptoms will lend suggestions of possible agents and eliminate some viruses, e. g. Rotavirus will not be seen in brain, nor Rabies in stool, but preconceived notions should not prejudice the observer into missing an unlikely pathogen.

Absolute inner-shell cross section determination for EELS analysis

1988 ◽  
Vol 46 ◽  
pp. 534-535
Author(s):  
P.A. Crozier
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absolute Cross Section ◽  
Specimen Thickness ◽  
Mass Thickness ◽  
Scattering Cross ◽  
Before And After ◽  
Estimated Error ◽  
Scattering Cross Sections ◽  
Electron Microscopist

Absolute inelastic scattering cross sections or mean free paths are often used in EELS analysis for determining elemental concentrations and specimen thickness. In most instances, theoretical values must be used because there have been few attempts to determine experimental scattering cross sections from solids under the conditions of interest to electron microscopist. In addition to providing data for spectral quantitation, absolute cross section measurements yields useful information on many of the approximations which are frequently involved in EELS analysis procedures. In this paper, experimental cross sections are presented for some inner-shell edges of Al, Cu, Ag and Au.Uniform thin films of the previously mentioned materials were prepared by vacuum evaporation onto microscope cover slips. The cover slips were weighed before and after evaporation to determine the mass thickness of the films. The estimated error in this method of determining mass thickness was ±7 x 107g/cm2. The films were floated off in water and mounted on Cu grids.

Valence electron spectroscopy of inhomogeneous media

1992 ◽  
Vol 50 (2) ◽  
pp. 1150-1151
Author(s):  
A. Howie ◽  
D.W. McComb
Keyword(s):  
Specific Gravity ◽  
Loss Function ◽  
Electron Spectroscopy ◽  
Valence Electron ◽  
Peak Height ◽  
Loss Functions ◽  
Loss Peak ◽  
High Energies ◽  
Valence Electron Density ◽  
Electron Microscopist

The bulk loss function Im(-l/ε (ω)), a well established tool for the interpretation of valence loss spectra, is being progressively adapted to the wide variety of inhomogeneous samples of interest to the electron microscopist. Proportionality between n, the local valence electron density, and ε-1 (Sellmeyer's equation) has sometimes been assumed but may not be valid even in homogeneous samples. Figs. 1 and 2 show the experimentally measured bulk loss functions for three pure silicates of different specific gravity ρ - quartz (ρ = 2.66), coesite (ρ = 2.93) and a zeolite (ρ = 1.79). Clearly, despite the substantial differences in density, the shift of the prominent loss peak is very small and far less than that predicted by scaling e for quartz with Sellmeyer's equation or even the somewhat smaller shift given by the Clausius-Mossotti (CM) relation which assumes proportionality between n (or ρ in this case) and (ε - 1)/(ε + 2). Both theories overestimate the rise in the peak height for coesite and underestimate the increase at high energies.

A program for simulation of changes in diffraction patterns with crystal rotations

1990 ◽  
Vol 48 (1) ◽  
pp. 544-545
Author(s):  
F.C. Mijlhoff ◽  
H.W. Zandbergenl
Keyword(s):  
Electron Microscope ◽  
Reciprocal Lattice ◽  
Extensive Training ◽  
Diffraction Mode ◽  
Diffraction Patterns ◽  
Electron Microscopist

Orientation of crystals for HREM is done in diffraction mode. To do this efficiently thorough knowledge of the electron microscope and the reciprocal lattice of the investigated material is essential. With respect to the electron microscope extensive training is required to obtain the ability to tilt a crystal in the desired orientation. Familiarity with the reciprocal lattice of the investigated materials has to be obtained by tilt experiments on a relatively large number of crystals in the electron microscope. Even for experienced electron microscopists this can be very time consuming.In order to be able to practice tilt experiments without using the electron microscope, a program to simulate the electron microscope in diffraction mode was developed. The inexperienced electron microscopist may use the program to practice tilting of crystals. The experienced microscopist can use the program to familiarize with the reciprocal lattice of materials, which have not been studied by him before.

scholarly journals The chronicles of coronaviruses: the electron microscope, the doughnut, and the spike

2020 ◽  
Vol 20 (2) ◽  
pp. 78-92
Author(s):  
K. Lalchhandama
Keyword(s):  
Electron Microscope ◽  
Large Measure ◽  
University Of Maryland ◽  
Infectious Bronchitis ◽  
Transmission Electron ◽  
American Model ◽  
Nobel Prize In Physics ◽  
Human Viruses ◽  
The University ◽  
Electron Microscopist

The advancement of medicine owes in large measure to a German engineer Ernst Ruska, whose invention of transmission electron microscope in 1931 won him the 1986 Nobel Prize in Physics, when it comes to infectious diseases. Encouraged by his physician brother Helmut Ruska to use the prototype instrument for the study of viruses, the course of virology was shifted to a different and unprecedented level. Virus could then be seen, identified and imaged. The University of Maryland happened to acquire an American model of transmission EM, the RCA EMU, using which the first structural study was done for the first known coronavirus (then was simply known as infectious bronchitis virus) in 1948. The virus was described as rounded bodies with filamentous projections. The magnification was not great and the resolution was poor. The study was followed by a series of studies using improved techniques and better EM spanning the next decade. An upgraded version RCA-EMU2A gave better images in 1957 and the virus was described as doughnut-like structure. Using Siemens Elmiskop, D.M. Berry and collaborators made the first high-resolution pictures in 1964. The thick envelope which gave doughnut-like appearance and filamentous projections reported before could be discerned as discrete pear-shaped projections called the spikes. These spikes form a corona-like halo around the virus, which were also seen in novel human viruses (B814 and 229E) that caused common colds. The discoverer of B814, David Tyrrell and his aid June Almeida, a magnificent electron microscopist, established that IBV, B814 and 229E were of the same kind of virus in 1967, which prompted to create the name coronavirus in 1968. This article further highlights the detail structural organisation of coronaviruses emanating from these pioneering research.

Single Processing of Tissue for Light and Electron Microscopy

1977 ◽  
Vol 35 ◽  
pp. 550-551 ◽  
Author(s):  
W. A. Burns ◽  
A. M. Bretschneider ◽  
A. B. Morrison
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Ultrastructural Level ◽  
Significant Problem ◽  
Diagnostic Ability ◽  
Large Samples ◽  
Microscopic Evaluation ◽  
Light Microscopist ◽  
Plastic Embedding ◽  
Electron Microscopist

Tissues for light and electron microscopy are traditionally processed separately. Different fixatives and embedding media are usually employed. Paraffin is unsuitable for electron microscopy and the small amounts of tissue generally embedded in plastic makes sampling a significant problem for the light, as well as the electron microscopist. Techniques, however, have been described for plastic embedding of large samples of tissue which can be sectioned at 1 μm. The added resolution of these thinner sections potentially increases the diagnostic ability of the light microscopist. These techniques have not been fully utilized in pathology. If one fixative were utilized and the quantity embedded in plastic were comparable to that which is normally processed for paraffin, then the investigator could use plastic sections for better light microscopic evaluation with the option of subsequent examination of the same region in the same block at an ultrastructural level.

Ultrastructural comparison of cynomolgus monkey liver samples following immersion fixation in different primary fixatives

1987 ◽  
Vol 45 ◽  
pp. 712-713
Author(s):  
M. A. Egy
Keyword(s):  
Electron Microscopy ◽  
Young Adult ◽  
Normal Control ◽  
Adult Male ◽  
Cynomolgus Monkey ◽  
Hepatic Tissue ◽  
Pathology Laboratory ◽  
Cynomolgus Monkeys ◽  
Monkey Liver ◽  
Electron Microscopist

This study was undertaken to find an optimal primary fixative for the assessment of ultrastructural morphology of hepatic tissue from cynomolgus monkeys under common constraints in a pathology laboratory. No single fixative for electron microscopy is suitable for every organ, species or application. Immersion fixation is prescribed when a limited amount of tissue is available from biopsies or when tissues must be shared with other investigators. In addition, tissues are often collected at another location and then sent to the electron microscopist so a delay is incurred before processing is completed. The ultrastructural effects of eight fixatives and two designed delays were evaluated in this study.Fresh hepatic tissue was excised from the left lateral hepatic lobe of normal control young adult male cynomolgus monkeys and fixed by immersion according to 8 protocols.

Modulation Transfer Functions of Photographic Emulsions

1980 ◽  
Vol 38 ◽  
pp. 228-229 ◽  
Author(s):  
David A. Grano ◽  
Kenneth H. Downing
Keyword(s):  
Transfer Functions ◽  
Computer Processing ◽  
Modulation Transfer ◽  
Critical Importance ◽  
Limited Ability ◽  
Modulation Transfer Functions ◽  
Processing Techniques ◽  
Transfer Of Information ◽  
Photographic Emulsions ◽  
Electron Microscopist

All photographic emulsions suffer, to varying degrees, from two flaws - they have a limited ability to record accurately minute details and they add noise to whatever they record. To the electron microscopist attempting to do high resolution work on biological material using low electron exposures, these flaws can be of critical importance. The choice of exposure, magnification and emulsion used will determine the amount of detail recorded and the relative influence of the added noise. These choices thus dictate the transfer of information from the image to the emulsion and limit its retrieval by optical and/or computer processing techniques. How does one make a sensible choice?

scholarly journals Dehydration and Rehydration Issues in Biological Tissue Processing for Electron Microscopy

2005 ◽  
Vol 13 (1) ◽  
pp. 32-35 ◽  
Author(s):  
Christian T. K.-H. Stadtländer
Keyword(s):  
Electron Microscopy ◽  
Biological Tissue ◽  
Specimen Preparation ◽  
Tissue Processing ◽  
Transmission Electron ◽  
Indispensable Tool ◽  
Processing Steps ◽  
Electron Microscopist

Electron microscopy (EM) is an indispensable tool for the study of ultrastructures of biological specimens. Every electron microscopist would like to process biological specimens for either scanning electron microscopy (SEM) or transmission electron microscopy (TEM) in a way that the specimens viewed under the electron microscope resemble those seen in vivo or in vitro under the light microscope. This is, however, often easier said than done because biological tissue processing for EM requires careful attention of the investigator with regard to the numerous processing steps involved in specimen preparation, such as fixation, dehydration, infiltration, embedding, and sectioning.

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