scholarly journals Transition from a punched-out dislocation to a slip dislocation revealed by electron tomography

2010 ◽  
Vol 25 (12) ◽  
pp. 2292-2296 ◽  
Author(s):  
Masaki Tanaka ◽  
Grace S. Liu ◽  
Tomonobu Kishida ◽  
Kenji Higashida ◽  
Ian M. Robertson
Keyword(s):  
Dislocation Loop ◽  
Electron Tomography ◽  
Single Crystal Silicon ◽  
Crystal Silicon ◽  
High Voltage Electron Microscopy ◽  
Slip Dislocation ◽  
Voltage Electron ◽  
Large Matrix ◽  
Prismatic Dislocation Loop ◽  
Oxide Precipitate

Punched-out dislocations emitted from an octahedral oxide precipitate in single-crystal silicon were investigated using high-voltage electron microscopy and tomography (HVEM-tomography) to understand the mechanism of softening caused by the oxide precipitates. In the present paper, direct evidence of the transition of a punched-out prismatic dislocation loop to a slip dislocation is presented. The punched-out dislocation grows into a large matrix dislocation loop by absorption of interstitial atoms, which were produced during oxide precipitation.

Correlated 3D Light and Electron Microscopy of Large, Complex Structures: Analysis of Transverse Tubules in Heart Failure

1998 ◽  
Vol 4 (S2) ◽  
pp. 440-441
Author(s):  
Maryann E. Martone ◽  
Andrea Thor ◽  
Stephen J. Young ◽  
Mark H. Ellisman.
Keyword(s):  
Electron Microscopy ◽  
Electron Tomography ◽  
Light And Electron Microscopy ◽  
Structural Features ◽  
Electron Microscopic Level ◽  
Specimen Preparation ◽  
Large Sample Size ◽  
Electron Microscopic ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron

Light microscopic imaging has experienced a renaissance in the past decade or so, as new techniques for high resolution 3D light microscopy have become readily available. Light microscopic (LM) analysis of cellular details is desirable in many cases because of the flexibility of staining protocols, the ease of specimen preparation and the relatively large sample size that can be obtained compared to electron microscopic (EM) analysis. Despite these advantages, many light microscopic investigations require additional analysis at the electron microscopic level to resolve fine structural features.High voltage electron microscopy allows the use of relatively thick sections compared to conventional EM and provides the basis for excellent new methods to bridge the gap between microanatomical details revealed by LM and EM methods. When combined with electron tomography, investigators can derive accurate 3D data from these thicker specimens. Through the use of correlated light and electron microscopy, 3D reconstructions of large cellular or subcellular structures can be obtained with the confocal microscope,

Electron tomographic quantitation of mineral distribution in different collagen zones of calcifying tendon

1991 ◽  
Vol 49 ◽  
pp. 190-191
Author(s):  
B. F. McEwen ◽  
W. J. Landis ◽  
M. J. Song
Keyword(s):  
Electron Tomography ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
Organic Matrix ◽  
High Voltage Electron Microscopy ◽  
3D Images ◽  
Mineral Distribution ◽  
Voltage Electron ◽  
First Time

The skeletal system of vertebrates is composed of hard tissue formed by the deposition of hydroxyapatite, a calcium phosphate salt, into an organic matrix that is principally collagen. Although bone and other vertebrate calcifying tissues have been well studied, the processes by which mineralization is initiated and regulated at the molecular level are incompletely understood. Recently these processes have been investigated through high resolution tomographic three-dimensional (3D) reconstruction of initial mineralization sites of calcifying tendon imaged by high-voltage electron microscopy (HVEM). Such tomographic reconstruction provided the first direct 3D images of crystallization sites and clearly established in vivo that, as indicated in earlier reports, initial crystals are thin, irregularly-shaped platelets rather than rod-shaped needles. The crystals develop in both length (along their crystallographic c-axis) and width but seem limited in thickness. Crystals in local tendon regions are approximately parallel to each other and fuse in coplanar alignments to form larger platelets within collagen. Crystal growth is thought to be initiated in hole zones of the protein and develop into adjacent overlap zones. In the present study, electron tomography has been used to quantitate the mineral distribution in collagen for the first time.

What HVEM tomographic reconstruction methods tell us about biological ultrastructure: Present and future developments

1991 ◽  
Vol 49 ◽  
pp. 436-437
Author(s):  
B. F. McEwen ◽  
J. Frank
Keyword(s):  
Electron Tomography ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
Structural Investigations ◽  
High Voltage Electron Microscopy ◽  
Future Developments ◽  
Voltage Electron ◽  
Reconstruction Methods ◽  
Different Depths ◽  
3D Information

For biological specimens, the primary application of high-voltage electron microscopy (HVEM) has been to enhance three-dimensional (3D) structural investigations. The chief advantage of higher accelerating voltages is that they enable imaging of thicker specimens which are correspondingly richer in 3D information. In order to realize this advantage, however, the specimen must be viewed from more than one direction so that features from different depths superimposed in a single projection may be separated. The simplest application of this approach is stereo viewing, which uses a pair of images viewed from directions separated by a relatively small angle. Due to its simpicity, stereo viewing is widely used but it has the disadvantages of being qualitative, subjective and limited in the amount of 3D information that can be revealed. These limitations can be overcome by electron tomography where several views of the specimen are collected over a wide angular range (up to 180°), entered into a computer, and a 3D image computed from these views according to well-established mathematical principles.

Variation in Dislocation Pattern Observed in SCS Films Fractured by Tensile Test: Effects of Film Thickness and Testing Temperature

2007 ◽  
Vol 1052 ◽  
Author(s):  
Shigeki Nakao ◽  
Taeko Ando ◽  
Shigeo Arai ◽  
Noriyuki Saito ◽  
Kazuo Sato
Keyword(s):  
Fracture Toughness ◽  
Film Thickness ◽  
Thick Film ◽  
Fracture Behavior ◽  
Single Crystal Silicon ◽  
Testing Temperature ◽  
Crystal Silicon ◽  
High Voltage Electron Microscopy ◽  
Ambient Temperatures ◽  
Dislocation Activity

AbstractThis paper reports a transition in the fracture behavior of micron-sized single-crystal-silicon (SCS) film in an MEMS structure for various film thicknesses and ambient temperatures. The mean fracture toughness of 4-µm-thick SCS films was 1.28 MPa at room temperature (RT), and the value increased as the film thickness decreased, reaching 2.91 MPa for submicron-thick films. The fracture toughness of 4-µm-thick film did not change for ambient temperatures ranging from RT to 60ºC. However, it drastically increased at 70ºC and reached 2.60 MPa at 150ºC. Enhanced dislocation activity in the SCS crystal near the fracture surface was observed on 1-µm-thick film at RT and 4-µm-thick film at 80ºC by high-voltage electron microscopy. This change in dislocation activity seemed to correlated with the transition in fracture behavior.

Three-dimensional reconstruction by HVEM tomography

1992 ◽  
Vol 50 (1) ◽  
pp. 580-581
Author(s):  
Bruce F. McEwen ◽  
Joachim Frank
Keyword(s):  
Electron Tomography ◽  
Three Dimensional ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Angular Interval ◽  
Dimensional Reconstruction ◽  
Low Pass ◽  
Image Density ◽  
Density Map ◽  
The Individual

Electron Tomography has recently emerged as an effective tool for three-dimensional (3D) ultrastructural analysis, particularly when combined with Intermediate or High Voltage Electron Microscopy (IVEM and HVEM) (reviewed in 1-3). In this approach a tilt series is recorded over a large angular range, up to 180°, typically with an angular interval of 2-5°. The individual images are digitized, rotationally and translationally aligned, the image density normalized, and finally the 3D reconstruction computed. After low pass filtration to the limiting resolution, the reconstruction volume can be examined by a growing number of computer graphic tools. The chief advantages of tomography are that: 1) the reconstruction is an objectively determined, uninterrupted 3D density map of the specimen, as seen in the electron microscope; and 2) the method is generally applicable to any sample which is sufficiently contrasted or isolated from its surrounding environment.

High Voltage Electron Microscopy of Ion-Milled Dental Enamel

1974 ◽  
Vol 32 ◽  
pp. 60-61
Author(s):  
L. D. Ackerman ◽  
S. H. Y. Wei
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Third Molar ◽  
Polarized Light ◽  
Dental Enamel ◽  
Longitudinal Section ◽  
Ion Milling ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron

Mature human dental enamel has presented investigators with several difficulties in ultramicrotomy of specimens for electron microscopy due to its high degree of mineralization. This study explores the possibility of combining ion-milling and high voltage electron microscopy as a means of circumventing the problems of ultramicrotomy.A longitudinal section of an extracted human third molar was ground to a thickness of about 30 um and polarized light micrographs were taken. The specimen was attached to a single hole grid and thinned by argon-ion bombardment at 15° incidence while rotating at 15 rpm. The beam current in each of two guns was 50 μA with an accelerating voltage of 4 kV. A 20 nm carbon coating was evaporated onto the specimen to prevent an electron charge from building up during electron microscopy.

A High Voltage Electron Microscopy Study of Sub-Oxide Formation in Vanadium

1971 ◽  
Vol 29 ◽  
pp. 212-213
Author(s):  
R. H. Geiss ◽  
R. L. Ladd ◽  
K. R. Lawless
Keyword(s):  
High Vacuum ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Ultra High Vacuum ◽  
Pure Oxygen ◽  
Pressure Oxidation ◽  
High Voltage Electron Microscopy ◽  
Oxidation Study ◽  
Voltage Electron ◽  
Good Agreement

Detailed electron microscope and diffraction studies of the sub-oxides of vanadium have been reported by Cambini and co-workers, and an oxidation study, possibly complicated by carbon and/or nitrogen, has been published by Edington and Smallman. The results reported by these different authors are not in good agreement. For this study, high purity polycrystalline vanadium samples were electrochemically thinned in a dual jet polisher using a solution of 20% H2SO4, 80% CH3OH, and then oxidized in an ion-pumped ultra-high vacuum reactor system using spectroscopically pure oxygen. Samples were oxidized at 350°C and 100μ oxygen pressure for periods of 30,60,90 and 160 minutes. Since our primary interest is in the mechanism of the low pressure oxidation process, the oxidized samples were cooled rapidly and not homogenized. The specimens were then examined in the HVEM at voltages up to 500 kV, the higher voltages being necessary to examine thick sections for which the oxidation behavior was more characteristic of the bulk.

Three-Dimensional Visualization of the T-System of Frog Muscle Using High Voltage Electron Microscopy and a Lanthanum Stain

1977 ◽  
Vol 35 ◽  
pp. 570-571 ◽  
Author(s):  
Lee D. Peachey ◽  
Clara Franzini-Armstrong
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Three Dimensional ◽  
Biological Tissues ◽  
High Voltage Electron Microscopy ◽  
Transverse Tubular System ◽  
Peroxidase Reaction ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
T System

The effective study of biological tissues in thick slices of embedded material by high voltage electron microscopy (HVEM) requires highly selective staining of those structures to be visualized so that they are not hidden or obscured by other structures in the image. A tilt pair of micrographs with subsequent stereoscopic viewing can be an important aid in three-dimensional visualization of these images, once an appropriate stain has been found. The peroxidase reaction has been used for this purpose in visualizing the T-system (transverse tubular system) of frog skeletal muscle by HVEM (1). We have found infiltration with lanthanum hydroxide to be particularly useful for three-dimensional visualization of certain aspects of the structure of the T- system in skeletal muscles of the frog. Specifically, lanthanum more completely fills the lumen of the tubules and is denser than the peroxidase reaction product.

Radiation-Induced Precipitation at Thin Foil Surfaces in Ni-Be Alloys

1982 ◽  
Vol 40 ◽  
pp. 598-599
Author(s):  
T. Mukai ◽  
T. E. Mitchell
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Electron Irradiation ◽  
High Vacuum ◽  
Thin Foil ◽  
Homogeneous Precipitation ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Radiation Induced

Radiation-induced homogeneous precipitation in Ni-Be alloys was recently observed by high voltage electron microscopy. A coupling of interstitial flux with solute Be atoms is responsible for the precipitation. The present investigation further shows that precipitation is also induced at thin foil surfaces by electron irradiation under a high vacuum.

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