scholarly journals High Voltage Microscopy in Paleontological Studies – Graptolites

1970 ◽  
Vol 28 ◽  
pp. 492-493
Author(s):  
W. B. N. Berry ◽  
R. S. Takagi ◽  
G. Thomas ◽  
D. J. Jurica
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
The Other ◽  
Transmission Power ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Transmission Electron ◽  
Thin Sectioning ◽  
Electron Microscopes ◽  
Biological Methods

Transmission electron microscopy has seldom been used in studies of fossils, and to date, no electron diffraction work has been reported. Because of the limited transmission power of the 100 kV electron microscopes (<lμ), the techniques which have been used to prepare specimens have followed standard biological methods, including ultra-thin sectioning and staining. High voltage electron microscopy on the other hand allows examination of considerably thicker specimens (up to 5μ at 500 kV) and is particularly useful in studying fossils e.g. it is often not necessary to section pieces of the fossil. Minimal preparation is advantageous because materials that have been interred in rocks of the earth's crust for millions of years are commonly brittle and distort or break while being sectioned with the microtome.

scholarly journals Diagnostic Electron Microscopy of Viruses With Low-voltage Electron Microscopes

2020 ◽  
Vol 68 (6) ◽  
pp. 389-402
Author(s):  
Lars Möller ◽  
Gudrun Holland ◽  
Michael Laue
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Voltage ◽  
Low Voltage ◽  
Optical Resolution ◽  
Plant Diseases ◽  
Voltage Electron ◽  
Transmission Electron ◽  
High Voltage Transmission ◽  
Electron Microscopes

Diagnostic electron microscopy is a useful technique for the identification of viruses associated with human, animal, or plant diseases. The size of virus structures requires a high optical resolution (i.e., about 1 nm), which, for a long time, was only provided by transmission electron microscopes operated at 60 kV and above. During the last decade, low-voltage electron microscopy has been improved and potentially provides an alternative to the use of high-voltage electron microscopy for diagnostic electron microscopy of viruses. Therefore, we have compared the imaging capabilities of three low-voltage electron microscopes, a scanning electron microscope equipped with a scanning transmission detector and two low-voltage transmission electron microscopes, operated at 25 kV, with the imaging capabilities of a high-voltage transmission electron microscope using different viruses in samples prepared by negative staining and ultrathin sectioning. All of the microscopes provided sufficient optical resolution for a recognition of the viruses tested. In ultrathin sections, ultrastructural details of virus genesis could be revealed. Speed of imaging was fast enough to allow rapid screening of diagnostic samples at a reasonable throughput. In summary, the results suggest that low-voltage microscopes are a suitable alternative to high-voltage transmission electron microscopes for diagnostic electron microscopy of viruses.

scholarly journals Some Current and Future Trends of High Voltage Transmission Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 2-3
Author(s):  
Gareth Thomas
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Materials Science ◽  
Future Trends ◽  
Light Elements ◽  
Special Effects ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Transmission Electron ◽  
Resolution Level

The Optimum Voltages for Electron Microscopy – The advantages of high voltage electron microscopy are now well established, and many applications, such as use of environmental cells both in metallurgy and biology, are now possible. However recent experiments at Toulouse indicate that except for light elements, there is no appreciable gain in transmission for a given resolution level as the energy is increased above 1 MeV (see Fig. 1). These results are not as optimistic as theory might indicate. Special effects such as critical voltages above 1 MeV are of interest, but knock-on radiation damage imposes limitations on many applications. Thus it would appear that 1 MeV is a reasonable upper limit for most applications in materials science.

Observations on Developing Blood Vessels in Rat Spinal Cord—A High Voltage Electron Microscopy Study

1974 ◽  
Vol 32 ◽  
pp. 66-67
Author(s):  
Richard S. Hannah
Keyword(s):  
Electron Microscopy ◽  
Spinal Cord ◽  
High Voltage ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
High Voltage Electron Microscopy ◽  
Thin Sections ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Transmission Electron

The formation of junctional complexes between endothelial cell processes was examined in rat spinal cords, from age birth to six weeks. Segments of spinal cord were removed from the region of the cervical enlargement and fixed. For comparative purposes, animals from each time group were subdivided into groups, fixed by either immersion or perfusion with an aldehyde combination in sodium cacodylate buffer and embedded in Araldite. Thin sections were examined by conventional transmission electron microscopy. Thick sections (0.5μ - 1.0μ) were stained with uranyl magnesium acetate for four hours at 60°C and lead citrate for 30 mins. and examined in the AEI Mark II High Voltage Electron Microscope.

Detection efficiency and estimation of the performance of high voltage STEM

1978 ◽  
Vol 36 (1) ◽  
pp. 84-85
Author(s):  
A. Ishikawa ◽  
C. Morita ◽  
M. Hibino ◽  
S. Maruse
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Radiation Damage ◽  
High Voltage ◽  
Detection Efficiency ◽  
Beam Current ◽  
High Energy ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Transmission Electron

One of the problems which are met in conventional transmission electron microscopy (CTEM) at high voltages is the reduction of the sensitivity of photographic films for high energy electron beams, resulting in the necessity of using high beam current. This cancels out an advantage of high voltage electron microscopy which is otherwise expected from the reduction of the inelastic scattering in the specimen, that is the reduced radiation damage of the specimen during observations. However, it is expected that the efficiency of the detector of scanning transmission electron microscopy (STEM) can be superior to that of CTEM, since the divergence of the electron beam in the detecting material does not affect the quality of the image. In addition to observation with less radiation damage, high voltage STEM with high detection efficiency is very attractive for observations of weak contrast objects since the enhancement of the contrast (which is an important advantage of STEM) is easily realized electrically.

High Voltage Electron Microscopy in Biology

1970 ◽  
Vol 28 ◽  
pp. 12-13
Author(s):  
Hans Ris
Keyword(s):  
Electron Microscopy ◽  
Heavy Metal ◽  
Electron Microscope ◽  
High Voltage ◽  
Cell Structure ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Sectioning Method ◽  
High Voltage Electron ◽  
Electron Microscopes

Conventional electron microscopes operate with accelerating voltages up to 100kV. Because of the scattering of electrons by atoms of the specimen an image with reasonable resolution can only be obtained with very thin specimens. The study of cell structure with the electron microscope became possible only with the introduction of ultramicrotomes which produce sections of plastic-embedded tissues down to about 100A in thickness. It has long been known that useful images could be obtained with much thicker materials at higher accelerating voltages (cf. refs. 1 and 2) and in the early sixties electron microscopes operating at voltages of up to one million Volts were built in Japan and in France. Their capabilities were soon demonstrated in metallurgy but they were ignored until recently by biologists. For one, biologists were busy exploiting the sectioning method and in addition may have been deterred by the knowledge that scattering contrast rapidly decreases at higher accelerating voltage. Only recently has it been realized that excellent contrast is obtained at 500 and 1000kV with the usual heavy metal stains (3,4). High voltage microscopes are now manufactured commercially in England (AEI), France (GESPA) and Japan (Hitachi, Jeol) and should soon be more widely accessible.

Integrated microscopy resource for biomedical research at the university of wisconsin at madison

1987 ◽  
Vol 45 ◽  
pp. 594-597 ◽  
Author(s):  
G. Schatten ◽  
J. Pawley ◽  
H. Ris
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
High Voltage ◽  
Biomedical Research ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
University Of Wisconsin ◽  
Transmission Electron ◽  
The University

The High Voltage Electron Microscopy Laboratory [HVEM] at the University of Wisconsin-Madison, a National Institutes of Health Biomedical Research Technology Resource, has recently been renamed the Integrated Microscopy Resource for Biomedical Research [IMR]. This change is designed to highlight both our increasing abilities to provide sophisticated microscopes for biomedical investigators, and the expansion of our mission beyond furnishing access to a million-volt transmission electron microscope. This abstract will describe the current status of the IMR, some preliminary results, our upcoming plans, and the current procedures for applying for microscope time.The IMR has five principal facilities: 1.High Voltage Electron Microscopy2.Computer-Based Motion Analysis3.Low Voltage High-Resolution Scanning Electron Microscopy4.Tandem Scanning Reflected Light Microscopy5.Computer-Enhanced Video MicroscopyThe IMR houses an AEI-EM7 one million-volt transmission electron microscope.

scholarly journals High Voltage Electron Microscopy at Berkeley

1970 ◽  
Vol 28 ◽  
pp. 2-3
Author(s):  
G. Thomas
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Voltage ◽  
Research Program ◽  
Transmission Power ◽  
Preparation Methods ◽  
High Voltage Electron Microscopy ◽  
High Energies ◽  
Voltage Electron ◽  
Thin Foils

A Hitachi 650kV electron microscope was installed at Berkeley in May 1969. (fig. 1) The fourier resolution test showed 4A° (fig. 2). The research program is centered around three principal advantages which open up new areas of microscopic analyses. These advantages are: a) the gain in transmission power with increasing voltage enabling thick specimens to be examined (up to about 6μ at 650kV depending on material) b) increased stability of roganic solids to radiation damage c) the disappearance voltage effect and fundamental advantages arising from many beam contrast phenomena at high energies.The increase in transmission enables materials to be examined for which preparation of thin foils is difficult. It also enables specimens to be examined in some cases without any preparation. In the study of fossils it is particularly important to minimize preparation methods since material which has been imbedded in rocks for millions of years are usually brittle and difficult to section. Fig. 3 shows an example of the fibious structure of part of a graptolite specimen, which is 4 × 108 years old. Another example is a study of damage in as-received lunar surface particles (fig. 4).

Sign in / Sign up

Export Citation Format

Share Document