Extracellular matrix assembly in diatoms (Bacillariophyceae). iv. ultrastructure ofAchnanthes longipesandCymbella cistulaas revealed by high-pressure freezing/freeze substituton and cryo-field emission scanning electron microscopy

2000 ◽  
Vol 36 (2) ◽  
pp. 367-378 ◽  
Author(s):  
Yan Wang ◽  
Ya Chen ◽  
Colleen Lavin ◽  
Michael R. Gretz
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Extracellular Matrix ◽  
High Pressure ◽  
Field Emission ◽  
High Pressure Freezing ◽  
Matrix Assembly ◽  
Scanning Electron

Morphology of the lateral fields of the infective juvenile of the entomopathogenic family Steinernematidae (Nematoda) using high pressure freezing (HPF)

Nematology ◽  
2019 ◽  
Vol 22 (1) ◽  
pp. 69-74
Author(s):  
Zdeněk Mráček ◽  
Jiří Nermut’ ◽  
Martina Tesařová ◽  
Vladimír Půža
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Pressure ◽  
Infective Juvenile ◽  
Field Pattern ◽  
Taxonomic Character ◽  
High Pressure Freezing ◽  
Lateral Field ◽  
Transmission Electron ◽  
Scanning Electron

Summary The lateral field pattern of infective juveniles of the nematode family Steinernematidae is an important taxonomic character. Scanning electron microscopy (SEM) shows the number of ridges and lines or incisures clearly, but does not provide other details. In the present study, ten species from six clades of Steinernematidae have been studied for their lateral field morphology using SEM and high pressure freezing (HPF) with transmission electron microscopy (TEM). Both methods indicated the same number of ridges and lines, although HPF/TEM resulted in a more detailed morphology with differences between the species. The tips of the ridges are either finely rounded or pointed and the lines are V-shaped or have a broadened bottom. These characters represent an additional pattern that may be characteristic for some species within the phylogenetic clades. Further studies of the lateral field morphology of other species is needed to ascertain whether each pattern is clade specific and phylogenetically valuable.

Characteristics of Micro/Nanopores and Their Petroleum Significance in the Eastern Segment of the Altun Piedmont, Qaidam Basin, Western China

2021 ◽  
Vol 21 (1) ◽  
pp. 181-194
Author(s):  
Qing-Bin Xie ◽  
Xin Li ◽  
Chuan-Long Li ◽  
Yong-Shu Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Pressure ◽  
Field Emission ◽  
Qaidam Basin ◽  
Western China ◽  
Tight Sandstone ◽  
Eastern Segment ◽  
Scanning Electron ◽  
Nuclear Magnetic

With continuous improvements in nanotechnology, the development of micro/nanoscale pores and fractures in reservoirs can be more clearly identified, and great progress has been made in tight sandstone and shale. Bedrock has an ultralow porosity and is a reservoir with low permeability. To study the characteristics of micro/nanoscale pore development and reveal their petroleum significance in the eastern segment of the Altun Piedmont, research has been conducted with the use of cathodoluminescence, field emission scanning electron microscopy and energy spectrum analysis, formation microresistivity image logging, high-pressure mercury injection and nuclear magnetic logging. The results have shown that the porosity of the bedrock reservoir in the eastern segment of the Altun Piedmont, as measured by helium injection and nuclear magnetic logging, is between 0.004% and 9.76%, the average porosity is between 1.663% and 3.844%, and the permeability is between the maximum of 0.002 mD and 33.239 mD. The average permeability is between 0.02 mD and approximately 3.836 mD. Micro/nanopores are generally developed, with the majority being intragranular micro/nanopores, intercrystalline micro/nanopores and microcracks, as summarized by the field emission scanning electron microscopy and energy dispersive spectroscopy analysis. Four differently sized pores develop: micropores account for approximately 20%, transition pores account for approximately 30%, and mesopores and macropores account for approximately 25% each. The pore throat development below 100 nm is greater than 50% according to the collation of experimental data from high-pressure mercury intrusion; therefore, micro/nanopores are the main storage space in the study area, and the gas logging shows good results. Micro/nanopores are also one of the main reservoir spaces of bedrock reservoirs in conjunction with the conventional reservoir space, and thus, micro/nanopores have important petroleum significance.

Imaging Plant Cells by High-Pressure Freezing and Serial block-face scanning electron microscopy

2020 ◽  
pp. 69-81
Author(s):  
Kirk Czymmek ◽  
Abhilash Sawant ◽  
Kaija Goodman ◽  
Janice Pennington ◽  
Pal Pedersen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Pressure ◽  
Plant Cells ◽  
High Pressure Freezing ◽  
Face Scanning ◽  
Block Face ◽  
Scanning Electron

A New Image Processing Technique for STEM

1974 ◽  
Vol 32 ◽  
pp. 432-433
Author(s):  
Yasushi Kokubo ◽  
Hirotami Koike ◽  
Teruo Someya
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Scanning Electron Microscopy ◽  
Elastic Scattering ◽  
Field Emission ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Energy Analyzer ◽  
Scanning Microscope ◽  
Scanning Electron

One of the advantages of scanning electron microscopy is the capability for processing the image contrast, i.e., the image processing technique. Crewe et al were the first to apply this technique to a field emission scanning microscope and show images of individual atoms. They obtained a contrast which depended exclusively on the atomic numbers of specimen elements (Zcontrast), by displaying the images treated with the intensity ratio of elastically scattered to inelastically scattered electrons. The elastic scattering electrons were extracted by a solid detector and inelastic scattering electrons by an energy analyzer. We noted, however, that there is a possibility of the same contrast being obtained only by using an annular-type solid detector consisting of multiple concentric detector elements.

Scattering of Electrons at High - Pressure and Restoration of Image Contrast in High Pressure Scanning Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 384-385
Author(s):  
J. S. Shah ◽  
R. Durkin ◽  
A. N. Farley
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Pressure ◽  
Cross Sections ◽  
Single Scattering ◽  
Image Contrast ◽  
Experimental Scheme ◽  
Medium Resolution ◽  
Scattering Approximation ◽  
Scanning Electron

It is now possible to perform High Pressure Scanning Electron Microscopy (HPSEM) in the range 10 to 2000 Pa. Here the effect of scattering on resolution has been evaluated by calculating the profile of the beam in high pressure and assessing its effect on the image contrast . An experimental scheme is presented to show that the effect of the primary beam ionization is to reduce image contrast but this effect can be eliminated by a novel use of specimen current detection in the presence of an electric field. The mechanism of image enhancement is discussed in terms of collection of additional carriers generated by the emissive components.High Pressure SEM (HPSEM) instrumentation is establishing itself as commercially viable. There are now a number of manufacturers, such as JEOL, ABT, ESCAN, DEBEN RESEARCH, selling microscopes and accessories for HPSEM. This is because high pressure techniques have begun to yield high quality micrographs at medium resolution.To study the effect of scattering on the incident electron beam, its profile - in a high pressure environment - was evaluated by calculating the elastic and inelastic scattering cross sections for nitrogen in the energy range 5-25 keV. To assess the effect of the scattered beam on the image contrast, the modification of a sharp step contrast function due to scattering was calculated by single scattering approximation and experimentally confirmed for a 20kV accelerated beam.

Neutrophil Derived Cathepsin G Induces Potentially Thrombogenic Changes in Human Endothelial Cells: a Scanning Electron Microscopy Study in Static and Dynamic Conditions

1994 ◽  
Vol 72 (01) ◽  
pp. 140-145 ◽  
Author(s):  
Valeri Kolpakov ◽  
Maria Cristina D'Adamo ◽  
Lorena Salvatore ◽  
Concetta Amore ◽  
Alexander Mironov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Thrombus Formation ◽  
Cathepsin G ◽  
Arterial Segment ◽  
Dynamic Conditions ◽  
Activated Neutrophils ◽  
Scanning Electron

SummaryActivated neutrophils may promote thrombus formation by releasing proteases which may activate platelets, impair the fibrinolytic balance and injure the endothelial monolayer.We have investigated the morphological correlates of damage induced by activated neutrophils on the vascular wall, in particular the vascular injury induced by released cathepsin G in both static and dynamic conditions.Human umbilical vein endothelial cells were studied both in a cell culture system and in a model of perfused umbilical veins. At scanning electron microscopy, progressive alterations of the cell monolayer resulted in cell contraction, disruption of the intercellular contacts, formation of gaps and cell detachment.Contraction was associated with shape change of the endothelial cells, that appeared star-like, while the underlying extracellular matrix, a potentially thrombogenic surface, was exposed. Comparable cellular response was observed in an “in vivo” model of perfused rat arterial segment. Interestingly, cathepsin G was active at lower concentrations in perfused vessels than in culture systems. Restoration of blood flow in the arterial segment previously damaged by cathepsin G caused adhesion and spreading of platelets on the surface of the exposed extracellular matrix. The subsequent deposition of a fibrin network among adherent platelets, could be at least partially ascribed to the inhibition by cathepsin G of the vascular fibrinolytic potential.This study supports the suggestion that the release of cathepsin G by activated neutrophils, f.i. during inflammation, may contribute to thrombus formation by inducing extensive vascular damage.

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