scholarly journals Crystallography of Growth Blocks in Spheroidal Graphite

2018 ◽  
Vol 925 ◽  
pp. 54-61 ◽  
Author(s):  
Etienne Brodu ◽  
Emmanuel Bouzy ◽  
Jean Jacques Fundenberger ◽  
Benoit Beausir ◽  
Lydia Laffont ◽  
...  

A better understanding of spheroidal graphite growth is expected in a near future thanks to widespread use of transmission electron microscopy. However, common transmission electron microscopy is quite time consuming and new indexing techniques are being developed, among them is transmission Kikuchi diffraction in a scanning electron microscope, a recent technique derived from electron backscatter diffraction. In the present work, on-axis transmission Kikuchi diffraction in scanning electron microscope, completed by transmission electron microscopy, was used with the objective of producing new observations on the microstructure of spheroidal graphite. This study shows that disorientations between blocks and sectors in spheroidal graphite are quite large in the early growth stage, which may be indicative of a competition process selecting the best orientations for achieving radial growth along thecdirection of graphite.

Author(s):  
William E. Vanderlinde

Abstract Recent developments in transmission electron microscopy (TEM) sample preparation have greatly reduced the time and cost for preparing thin samples. In this paper, a method is demonstrated for viewing thin samples in transmission in an unmodified scanning electron microscope (SEM) using an easily constructed sample holder. Although not a substitute for true TEM analysis, this method allows for spatial resolution that is superior to typical SEM imaging and provides image contrast from material structure that is typical of TEM images. Furthermore, the method can produce extremely high resolution x-ray maps that are typically produced only by scanning transmission electron microscope (STEM) systems.


2012 ◽  
Vol 18 (5) ◽  
pp. 1037-1042 ◽  
Author(s):  
Yun-Wen You ◽  
Hsun-Yun Chang ◽  
Hua-Yang Liao ◽  
Wei-Lun Kao ◽  
Guo-Ji Yen ◽  
...  

AbstractBased on a scanning electron microscope operated at 30 kV with a homemade specimen holder and a multiangle solid-state detector behind the sample, low-kV scanning transmission electron microscopy (STEM) is presented with subsequent electron tomography for three-dimensional (3D) volume structure. Because of the low acceleration voltage, the stronger electron-atom scattering leads to a stronger contrast in the resulting image than standard TEM, especially for light elements. Furthermore, the low-kV STEM yields less radiation damage to the specimen, hence the structure can be preserved. In this work, two-dimensional STEM images of a 1-μm-thick cell section with projection angles between ±50° were collected, and the 3D volume structure was reconstructed using the simultaneous iterative reconstructive technique algorithm with the TomoJ plugin for ImageJ, which are both public domain software. Furthermore, the cross-sectional structure was obtained with the Volume Viewer plugin in ImageJ. Although the tilting angle is constrained and limits the resulting structural resolution, slicing the reconstructed volume generated the depth profile of the thick specimen with sufficient resolution to examine cellular uptake of Au nanoparticles, and the final position of these nanoparticles inside the cell was imaged.


Parasitology ◽  
1970 ◽  
Vol 61 (2) ◽  
pp. 219-227 ◽  
Author(s):  
H. D. Chapman ◽  
R. A. Wilson

The distribution of the integumentary papillae of the cercaria ofHimasthla secundahas been studied by a variety of techniques. Structures stained by silver nitrate and visible under the light microscope correspond in their spatial distribution with papillae observed under the scanning electron microscope. The tegumentary papillae described with the light and scanning electron microscope are correlated with the specialized nerve endings in the tegument as seen in transmission electron microscopy. The ultrastructure of these papillae is examined by conventional transmission electron microscopy and the probability that these structures are sensory is discussed.


1984 ◽  
Vol 62 (10) ◽  
pp. 2081-2093 ◽  
Author(s):  
Rosmarie Honegger

The conidiomata, conidiophores, and conidia of six lichen-forming Ascomycetes were investigated using the scanning electron microscope, and conidium development in two of these species was studied by transmission electron microscopy. Phialidic (micro) conidium formation was observed in the mycobiont of Parmelia tiliacea, Physconia pulverulacea, and Cladonia furcata (Lecanorales), in Lobaria laetevirens (Peltigerales), and in Caloplaca aurantia (Teloschistales). Annellations, first described by Vobis on the basis of light and transmission electron microscope investigations, were also found in scanning electron microscope preparations of macroconidia bearing conidiogenous cells of Lecanactis abietina (Opegraphales). Ultrastructural and developmental studies on conidiophore structure and conidium formation may be of interest for taxonomic and evolutionary considerations in lichen-forming fungi.


2008 ◽  
Vol 16 (6) ◽  
pp. 28-35
Author(s):  
William Vanderlinde

Everyone always wants better resolution from his or her microscopes. With semiconductor manufacturers now shipping product with sub-100 nm gates, measuring features and defects has become a challenge, even for the scanning electron microscope (SEM). For metrology below 100 nm, some manufacturers have begun routinely using TEM (transmission electron microscopy) which is tedious and expensive. As a microscopist, I find this quite disappointing since, in principle, the SEM should be capable of providing more than enough resolution well below 100 nm. Why is it that SEMs with 1 nm spot size can’t provide adequate resolution for 100 nm gates? It turns out that at very high magnification, SEM resolution is limited by how the electron beam interacts with the sample rather than simply the spot size of the beam.


Author(s):  
V. R. Mumaw ◽  
B. L. Munger

The use of the scanning electron microscope (SEM) has become a very useful tool complimenting studies done by transmission electron microscopy (TEM). The presence of cilia in the renal epithelium have been noted by various investigators and described by Latta. The present study utilizing the SEM and a freeze fracture technique demonstrates the regularity of cilia as well as the surface topography of the renal epithelium in a fractured profile.


Author(s):  
A. Julio Martinez ◽  
E. Clifford Nelson ◽  
Doris G. Fultz ◽  
Ragnit Geeraets

Scanning electron microscopy (SEM) can serve as a valuable supplement to transmission electron microscopy (TEM) in the study of pathogenic protozoa. Details of overall form and structure of surface and organelles which may have a role in pathogenicity may be revealed. TEM studies on Naegleria have contributed much to understanding the extraordinary virulence of this ameba, but some remaining questions may be resolved by SEM. This report describes a technique which has proven useful in preparing SEM specimens. Naegleria ameba trophozoites adhere strongly to the surface on which they are growing. In culture tubes, amebae will multiply on the wall. Naegleria tends to grow from the top of the fluid downward and may multiply until a solid monolayer develops. If a strip of plastic film is introduced, the growth on the strip can be observed by direct microscope viewing through the wall of the tube.


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