scholarly journals Diffraction Contrast from Dissociated Frank Dislocations. I. Computed Electron Micrographs

1969 ◽  
Vol 22 (3) ◽  
pp. 351 ◽  
Author(s):  
LM Clarebrough ◽  
AJ Morton
Keyword(s):  
Electron Microscope ◽  
Electron Micrographs ◽  
Degree Of Dissociation ◽  
Diffraction Contrast ◽  
Microscope Images

The influence of degree of dissociation on the diffraction contrast from a Frank dislocation for lll, 220, and 020 reflections has been investigated using the technique devised by Head and Humble for computing electron microscope images.

Electron Microscope Observations of Magnetic and Electric Effects

1970 ◽  
Vol 28 ◽  
pp. 430-431
Author(s):  
John Silcox
Keyword(s):  
Electron Microscope ◽  
Electric Fields ◽  
Magnetic Image ◽  
Magnetic Effects ◽  
Ferromagnetic Films ◽  
Diffraction Contrast ◽  
Microscope Images ◽  
Electric Effects ◽  
Image Detail

Several aspects of magnetic and electric effects in electron microscope images are of interest and will be discussed here. Clearly electrons are deflected by magnetic and electric fields and can give rise to image detail. We will review situations in ferromagnetic films in which magnetic image effects are the predominant ones, others in which the magnetic effects give rise to rather subtle changes in diffraction contrast, cases of contrast at specimen edges due to leakage fields in both ferromagnets and superconductors and some effects due to electric fields in insulators.

scholarly journals Studies in Oberonia, 9: Lessons from excess names in Oberonia for Orchidaceae systematics, including a revision of the Oberonia Sect. Scytoxiphium

Lankesteriana ◽  
2021 ◽  
Author(s):  
Daniel L. Geiger
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Electron Micrographs ◽  
21St Century ◽  
Expert Advice ◽  
Scanning Electron Micrographs ◽  
Palabras Clave ◽  
Microscope Images ◽  
Typological Thinking ◽  
Scanning Electron

The reasons for excess names in microfloral orchids such as Oberonia Lindl. can be traced to poor scholarship (e.g., failure to review the literature, ignoring expert advice), typological thinking, and erroneous assumption of microendemism. Some extraordinarily poor descriptions, including some from the 21st century, can be termed “taxonomic vandalism”. The outdated reliance on drawings as opposed to z-stacked photographs and scanning electron micrographs poses further problems due to an abundance of demonstrable problems with drawings. The Oberonia sect. Scytoxiphium Schltr. with eight described species is reduced to one species, Oberonia heliophila Rchb.f.; it is illustrated by original drawings, live photographs and scanning electron microscope images. The distribution is extended from Java through Micronesia and Samoa. The species occurs predominantly from 0–500 m, less frequently to 900 m, and possibly to even 1900 m. It flowers throughout the year. Keywords/Palabras clave: Oberonia, Oberonia sect. Scytoxiphium, revision, revisión, synonymies, sinonimias, taxonomic vandalism, vandalismo taxonómico

scholarly journals Diffraction Contrast from Dissociated Frank Dislocations. II. Comparison of Experimental and Computed Electron Micrographs

1969 ◽  
Vol 22 (3) ◽  
pp. 371 ◽  
Author(s):  
LM Clarebrough ◽  
AJ Morton
Keyword(s):  
Electron Micrographs ◽  
Aluminium Alloys ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Dislocation Loops ◽  
Degree Of Dissociation ◽  
Diffraction Contrast

Experimental and computed images for edges of Frank dislocation loops in quenched copper-aluminium alloys and in quenched silver are compared. The comparison shows that Frank dislocations are dissociated in these materials. By matching the computed and experimental images, the degree of dissociation is determined and the stacking fault energy of the various materials is estimated.

scholarly journals Arrangement of Subunits in Flagellar Microtubules

1974 ◽  
Vol 14 (3) ◽  
pp. 523-549 ◽  
Author(s):  
LINDA A. AMOS ◽  
A. KLUG
Keyword(s):  
Electron Microscope ◽  
Electron Micrographs ◽  
Helical Surface ◽  
3 Dimensional ◽  
Additional Information ◽  
Microscope Images ◽  
Staggered Arrangement ◽  
Diffraction Patterns ◽  
Tubule Wall

Electron micrographs of outer doublet tubules from flagella have been analysed by methods which make use of the computed diffraction patterns of electron-microscope images. Analysis of singlet A-tubules in the tips of flagella has led to a determination of the helical surface lattice of the A-subfibre, confirming that there are 13 longitudinal protofilaments in the tubule wall and that dimers in neighbouring protofilaments form a staggered arrangement, equivalent to the lattice with an axial periodicity of 8.0 nm predicted in earlier work. A low-resolution 3-dimensional image of the A-tubule has been reconstructed, which supports the evidence for an 8.0-nm-long heterodimer oriented along the protofilaments. The heterodimer is identified as a pair of 4.0-nm morphological units, which appear to be globular at this resolution. Filtered images have been obtained from doublet tubules which show that the B-subfibre is also made up of 8.0-nm dimers, but it differs from the A-tubule in that dimers in adjacent filaments are not in a staggered arrangement but are lined up obliquely at a shallow angle. Using the additional information about the hands of the lattices in the 2 subfibres which is presented in the accompanying paper, a model for the whole doublet has been proposed.

Utilizing Dark Field Electron Microscopy to Produce Lantern Slides

1974 ◽  
Vol 32 ◽  
pp. 116-117
Author(s):  
J. N. Meador ◽  
C. N. Sun ◽  
H. J. White
Keyword(s):  
Electron Microscope ◽  
Electron Micrographs ◽  
Dark Field ◽  
Limiting Factor ◽  
Clinical Laboratories ◽  
Field Electron ◽  
Time Element ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Dark Field Micrographs

The electron microscope is being utilized more and more in clinical laboratories for pathologic diagnosis. One of the major problems in the utilization of the electron microscope for diagnostic purposes is the time element involved. Recent experimentation with rapid embedding has shown that this long phase of the process can be greatly shortened. In rush cases the making of projection slides can be eliminated by taking dark field electron micrographs which show up as a positive ready for use. The major limiting factor for use of dark field micrographs is resolution. However, for conference purposes electron micrographs are usually taken at 2.500X to 8.000X. At these low magnifications the resolution obtained is quite acceptable.

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