Diffraction Contrast Transmission Electron Microscopy on Flax Fiber Ultrathin Cross Sections

1988 ◽  
Vol 58 (7) ◽  
pp. 414-417 ◽  
Author(s):  
P. Näslund ◽  
R. Vuong ◽  
H. Chanzy ◽  
J. C. Jésior
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Micrographs ◽  
Cross Sections ◽  
Flax Fiber ◽  
Flax Fibers ◽  
Diffraction Contrast ◽  
Cutting Angle ◽  
Transmission Electron ◽  
Diamond Knife

The crystalline ultrastructure of flax fibers was studied using diffraction contrast transmission electron microscopy applied to ultrathin transverse sections obtained with an experimental diamond knife with a cutting angle of only 26.6°. This technique permitted the recording of electron micrographs where individual crystalline microfibrils could be seen in the middle of their tightly packed arrangements. The microfibrils in flax had diameters ranging from 1 to 4 nm; in some instances their angular and nearly square contours were revealed.

Chitin Systems Studied by Electron Diffraction, Diffraction-Contrast Electron Microscopy and Lattice Imaging

1990 ◽  
Vol 48 (1) ◽  
pp. 582-583 ◽  
Author(s):  
Henri CHANZY ◽  
Francoise Gaill ◽  
Marie-Madeleine Giraud-Guille ◽  
Jan Persson ◽  
Junji Sugiyama ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Electron Diffraction ◽  
Cross Sections ◽  
Room Temperature ◽  
Lattice Imaging ◽  
Diffraction Contrast ◽  
Transmission Electron ◽  
Tevnia Jerichonana

Chitin the poly β (1-4)-N Acetyl D glucosamine is widespread in nature and occurs normally as a crystalline fibrillar substance. As opposed to most of the crystalline polysaccharides, chitin is quite resistant to the electron beam. In particular, at room temperature, accumulated doses as high as 200 elec/nm2 at 120 kV can be used to record successful images showing crystalline details. For this reason, chitin can be studied without too much difficulty by electron diffraction (ED), diffraction contrast transmission electron microscopy (DCTEM) and lattice imaging. This study presents some of the diversity of chitin morphology.Several chitin rich specimens were studied. They include : 1) cross sections of an ovipositor from an ichneumon fly Rhyssa persuosaria ; 2) cross sections of fragments of demineralized crab cuticle ; 3) cross sections of a tube from the vestimentiferan worm Tevnia jerichonana ; 4) bundles of chitin microfibrils isolated from Tevnia tube fragments after deproteinization.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

Enamel Crystal Shape: History of an Idea

1987 ◽  
Vol 1 (2) ◽  
pp. 322-329 ◽  
Author(s):  
H. Warshawsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cross Sections ◽  
Three Dimensional ◽  
Unit Cell ◽  
Cross Sectional ◽  
Transmission Electron ◽  
History Of ◽  
Sectional Shape ◽  
Imaging Plane

The purpose of this paper is to review evidence which casts doubt on the interpretation universally applied to hexagonal images seen in sectioned enamel. The evidence is based on two possible models to explain the hexagonal profiles seen in mammalian enamel with transmission electron microscopy. The "hexagonal ribbon" model proposes that hexagonal profiles are true cross-sections of elongated hexagonal ribbons. The "rectangular ribbon" model proposes that hexagonal profiles are caused by three-dimensional segments that are parallelepipeds contained in the Epon section. Since shadow projections of such rectangular segments give angles that are inconsistent with the hexagonal unit cell, a model based on ribbons with rhomboidal cut ends and angles of 60 and 120° is proposed. The "rhomboidal ribbon" model projects shadows with angles that are predicted by the unit cell. It is suggested that segments of such crystallites in section project as opaque hexagons on the imaging plane in routine transmission electron microscopy. Morphological observations on crystallites in sections - together with predictions from the hexagonal, rectangular, and rhomboidal ribbon models - indicate that crystallites in rat incisor enamel are flat ribbons with rhomboidal cross-sectional shape. Hexagonal images in electron micrographs of thin-sectioned enamel can result from rhomboidal-ended, parallelepiped-shaped segments of these crystallites projected and viewed as two-dimensional shadows.

scholarly journals Improved Sectioning of Polymers Using an Oscillating Diamond Knife for Transmission Electron Microscopy

2006 ◽  
Vol 14 (5) ◽  
pp. 20-21 ◽  
Author(s):  
J.D. Harris ◽  
J.S. Vastenhout
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Wedge Angle ◽  
Cutting Speed ◽  
Sample Surface ◽  
Section Thickness ◽  
Thin Sections ◽  
Transmission Electron ◽  
Surface Section ◽  
Diamond Knife

Polymers are viscoelastic materials that can often deform during microtome sectioning. Similar to plastic embedded biological materials, many methods have been developed over the years to not only improve the image contrast of these materials but also to harden the material for improved sectioning during microtomy. Even with these improvements, a common artifact, compression, during the sectioning of this class of materials remains problematic.Compression is caused by several factors: hardness of the sample, embedding media, wedge angle of the knife, interaction between the diamond and sample surface, section thickness and cutting speed. It has been found that reducing the knife angle from 45º to 35° leads to a reduction in compression. Recent efforts to further reduce the compression of ultra-thin sections have led to the invention of an oscillating diamond knife.

scholarly journals Electron tomography imaging methods with diffraction contrast for materials research

Microscopy ◽  
2020 ◽  
Vol 69 (3) ◽  
pp. 141-155
Author(s):  
Satoshi Hata ◽  
Hiromitsu Furukawa ◽  
Takashi Gondo ◽  
Daisuke Hirakami ◽  
Noritaka Horii ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Tomography ◽  
Atomic Resolution ◽  
Current Status ◽  
Research Trend ◽  
Imaging Methods ◽  
Diffraction Contrast ◽  
Transmission Electron ◽  
Materials Research

ABSTRACT Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) enable the visualization of three-dimensional (3D) microstructures ranging from atomic to micrometer scales using 3D reconstruction techniques based on computed tomography algorithms. This 3D microscopy method is called electron tomography (ET) and has been utilized in the fields of materials science and engineering for more than two decades. Although atomic resolution is one of the current topics in ET research, the development and deployment of intermediate-resolution (non-atomic-resolution) ET imaging methods have garnered considerable attention from researchers. This research trend is probably not irrelevant due to the fact that the spatial resolution and functionality of 3D imaging methods of scanning electron microscopy (SEM) and X-ray microscopy have come to overlap with those of ET. In other words, there may be multiple ways to carry out 3D visualization using different microscopy methods for nanometer-scale objects in materials. From the above standpoint, this review paper aims to (i) describe the current status and issues of intermediate-resolution ET with regard to enhancing the effectiveness of TEM/STEM imaging and (ii) discuss promising applications of state-of-the-art intermediate-resolution ET for materials research with a particular focus on diffraction contrast ET for crystalline microstructures (superlattice domains and dislocations) including a demonstration of in situ dislocation tomography.

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