Observations of thick and thin sections in a field-emission SEM

1994 ◽  
Vol 52 ◽  
pp. 1018-1019
Author(s):  
W. P. Wergin ◽  
S. Roy ◽  
E. F. Erbe ◽  
C. A. Murphy ◽  
C. D. Pooley
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Uranyl Acetate ◽  
Chemical Fixation ◽  
Thin Sections ◽  
Transmission Electron ◽  
Conventional Transmission Electron Microscope ◽  
Scanning Electron

Larvae of the nematode, Steinernema carpocapsae Weiser strain All, were cryofixed and freezesubstituted for 3 days in acetone containing 2% osmium tetroxide according to established procedures. Following chemical fixation, the nematodes were brought to room temperature, embedded in Spurr's medium and sectioned for observation with a Hitachi S-4100 field emission scanning electron microscope that was equipped with an Oxford CT 1500 Cryotrans System. Thin sections, about 80 nm thick, similar to those generally used in conventional transmission electron microscope (TEM) studies were mounted on copper grids and stained with uranyl acetate for 30 min and lead citrate for 5 min. Sections about 2 μm thick were also mounted and stained in a similar fashion. The grids were mounted on an Oxford grid holder, inserted into the microscope and onto a cryostage that was operated at ambient temperature. Thick and thin sections of the larvae were evaluated and photographed in the SEM at different accelerating voltages. Figs. 4 and 5 have undergone contrast conversion so that the images would resemble transmitted electron micrographs obtained with a TEM.

Mesosome-like Structures in Cryptococcus neoformans Studied by Chemical Fixation and by the Freeze-etching Technique

1968 ◽  
Vol 26 ◽  
pp. 80-81
Author(s):  
M. R. Edwards ◽  
S. C. Holt
Keyword(s):  
Electron Microscope ◽  
Cryptococcus Neoformans ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Chemical Fixation ◽  
Etching Technique ◽  
Pathogenic Yeast ◽  
Thin Sections ◽  
Lead Salts ◽  
Freeze Etching

The general features of Cryptococcus neoformans, a pathogenic yeast, have been studied with the electron microscope. In the course of such a study it was noted that the plasma membrane of C. neoformans, occasionally invaginated into the cytoplasm and formed membranous organelles which resembled bacterial mesosomes. The present investigation was undertaken in order to examine such structures in detail and to compare the results from chemical fixation with those of freeze-etching.Cells were grown in Sabouraud's agar at 25-27° C for 24-48 hr and fixed with 4% glutaraldehyde in 0.15 M phosphate (Sbrensen's) buffer, at room temperature, for 2 hr; after being thoroughly washed in the buffer and post-fixed in osmium tetroxide, in the same buffer, they were dehydrated in ethyl alcohol and embedded in Epon. Thin sections were cut in a LKB microtome, double stained with uranyl and lead salts and examined in the Siemens Elmiskop IA.

Resolution of a Transmitted Electron Image Formed by A Scanning Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 386-387
Author(s):  
S. Takashima ◽  
H. Hashimoto ◽  
S. Kimoto
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Specimen Thickness ◽  
Probe Diameter ◽  
Transmission Electron ◽  
Electron Image ◽  
Conventional Transmission Electron Microscope ◽  
Scanning Electron

The resolution of a conventional transmission electron microscope (TEM) deteriorates as the specimen thickness increases, because chromatic aberration of the objective lens is caused by the energy loss of electrons). In the case of a scanning electron microscope (SEM), chromatic aberration does not exist as the restrictive factor for the resolution of the transmitted electron image, for the SEM has no imageforming lens. It is not sure, however, that the equal resolution to the probe diameter can be obtained in the case of a thick specimen. To study the relation between the specimen thickness and the resolution of the trans-mitted electron image obtained by the SEM, the following experiment was carried out.

SEM Examination of a Used Diamond Knife

1971 ◽  
Vol 29 ◽  
pp. 452-453
Author(s):  
J. Temple Black
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
High Magnification ◽  
Metallic Materials ◽  
Wide Spread ◽  
Thin Sections ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Scanning Electron ◽  
Diamond Knife

Since its introduction by Fernandez-Moran, the diamond knife has gained wide spread usage as a common material for cutting of thin sections of biological and metallic materials into thin films for examination in the transmission electron microscope. With the development of high voltage E.M. and scanning transmission E.M., microtomy applications will become increasingly important in the preparation of specimens. For those who can afford it, the diamond knife will thus continue to be an important tool to accomplish this effort until a cheaper but equally strong and sharp tool is found to replace the diamond, glass not withstanding.In Figs. 1 thru 3, a first attempt was made to examine the edge of a used (β=45°) diamond knife by means of the scanning electron microscope. Because diamond is conductive, first examination was tried without any coating of the diamond. However, the contamination at the edge caused severe charging during imaging. Next, a thin layer of carbon was deposited but charging was still extensive at high magnification - high voltage settings. Finally, the knife was given a light coating of gold-palladium which eliminated the charging and allowed high magnification micrographs to be made with reasonable resolution.

Ultrastructural comparison of prolactin adenomas of pituitary in men and women

1988 ◽  
Vol 46 ◽  
pp. 346-347
Author(s):  
R.C. Caughey ◽  
U.P. Kalyan-Raman
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Phosphate Buffer ◽  
Pituitary Adenomas ◽  
Osmium Tetroxide ◽  
Secretory Granules ◽  
Uranyl Acetate ◽  
En Bloc ◽  
Men And Women ◽  
Transmission Electron

Prolactin producing pituitary adenomas are ultrastructurally characterized by secretory granules varying in size (150-300nm), abundance of endoplasmic reticulum, and misplaced exocytosis. They are also subclassified as sparsely or densely granulated according to the amount of granules present. The hormone levels in men and women vary, being higher in men; so also the symptoms vary between both sexes. In order to understand this variation, we studied 21 prolactin producing pituitary adenomas by transmission electron microscope. This was out of a total of 80 pituitary adenomas. There were 6 men and 15 women in this group of 21 prolactinomas.All of the pituitary adenomas were fixed in 2.5% glutaraldehyde, rinsed in Millonig's phosphate buffer, and post fixed with 1% osmium tetroxide. They were then en bloc stained with 0.5% uranyl acetate, rinsed with Walpole's non-phosphate buffer, dehydrated with graded series of ethanols and embedded with Epon 812 epoxy resin.

The Observation of NBC Precipitates In Steels In The Nanometer Range Using A Field Emission Gun Scanning Electron Microscope

1997 ◽  
Vol 3 (S2) ◽  
pp. 1243-1244 ◽  
Author(s):  
Raynald Gauvin ◽  
Steve Yue
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Incident Electron Energy ◽  
Beam Diameter ◽  
Probe Diameter ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

The observation of microstructural features smaller than 300 nm is generally performed using Transmission Electron Microscopy (TEM) because conventional Scanning Electron Microscopes (SEM) do not have the resolution to image such small phases. Since the early 1990’s, a new generation of microscopes is now available on the market. These are the Field Emission Gun Scanning Electron Microscope with a virtual secondary electron detector. The field emission gun gives a higher brightness than those obtained using conventional electron filaments allowing enough electrons to be collected to operate the microscope with incident electron energy, E0, below 5 keV with probe diameter smaller than 5 nm. At 1 keV, the electron range is 60 nm in aluminum and 10 nm in iron (computed using the CASINO program). Since the electron beam diameter is smaller than 5 nm at 1 keV, the resolution of these microscopes becomes closer to that of TEM.

Ultrafast Response Humidity Sensor Based on Electrospun Porous BaTiO3 Nanofibers

2013 ◽  
Vol 319 ◽  
pp. 43-48 ◽  
Author(s):  
Hong Di Zhang ◽  
Chen Hao Sheng ◽  
Bin Sun ◽  
Yun Ze Long
Keyword(s):  
Electron Microscope ◽  
Recovery Time ◽  
Room Temperature ◽  
Humidity Sensor ◽  
Humidity Sensing ◽  
X Ray ◽  
Transmission Electron ◽  
Porous Microstructure ◽  
Humidity Sensing Properties ◽  
Scanning Electron

Nanocrystalline and porous barium titanate (BaTiO3) nanofibers with diameter 200-400 nm were synthesized via electrospinning and followed calcinations. The morphology and microstructure of the nanofibers were characterized using field emission scanning electron microscope, X-ray diffractometer and transmission electron microscope, respectively. And the electrical and humidity sensing properties of the nanofibers were also measured. The results reveal that the BaTiO3 nanofibers have a conductivity of about 0.3 S/cm, and show an ultrafast response time (~0.7 s) and a recovery time (~0.4 s) to humidity at room temperature. In addition, the sensing mechanism was also discussed briefly based on its nanocrystalline and porous microstructure of the electrospun material.

Preparation of Helminths For Scanning Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 438-439
Author(s):  
Robert W. Weise
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Room Temperature ◽  
Parasitic Nematodes ◽  
Live Animal ◽  
Transmission Electron ◽  
Critical Point Drying ◽  
Scanning Electron

The role that scanning electron microscopy (SEM) is playing in descriptive helminthology is becoming more apparent in the literature. However, the majority of papers on the SEM of helminths have used conventional or modified light microscope techniques of fixation and dehydration, and not established SEM techniques in which freeze- and critical point-drying are routinely used. The present investigation was undertaken to examine the applicability of modified scanning and transmission electron microscope techniques for the preparation of certain helminths for SEM.Method I.– Live animal-parasitic nematodes were fixed in 6% phosphate buffered glutaraldehyde for 24 hr at room temperature.

Nonspecific structures seen in diagnostic muscle biopsies

1987 ◽  
Vol 45 ◽  
pp. 846-847
Author(s):  
R. C. Caughey ◽  
U. P. Kalyan-Raman
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Osmium Tetroxide ◽  
Clinical History ◽  
Uranyl Acetate ◽  
Ethanol Dehydration ◽  
Tubular Aggregates ◽  
En Bloc ◽  
Transmission Electron ◽  
Muscle Biopsies

In a period of two years we have analyzed 50 muscle biopsies using the transmission electron microscope. Six nonspecific structures consisting of filamentous bodies, tubular aggregates, paracrystalline mitochondrial inclusions, honeycomb arrays, concentric laminated bodies, and finger print profiles were observed in 47 of 50 cases. In order to know the significance of these structures in muscle biopsies, we correlated their occurrence with their clinical history, histological findings, and histochemistry.The biopsies were initially fixed in 2.5% glutaraldehyde (pH. 7.5, 500 mOsm), then randomly minced and post fixed in 1% osmium tetroxide. All biopsies were processed with and without uranyl acetate en bloc staining in Walpole's buffer before ethanol dehydration. They were embedded in Epon 812 epoxy resin, sectioned, and stained with uranyl acetate and lead citrate before evaluation with a JEOL, JEM 100 C Transmission Electron Microscope. All grid squares of six different blocks were scanned to evaluate the ultra-structural pathology.

Electron Microscopy as an aid to diagnosis in pediatric hematology/oncology

1989 ◽  
Vol 47 ◽  
pp. 1062-1063
Author(s):  
K. L. Saving ◽  
R. C. Caughey
Keyword(s):  
Electron Microscopy ◽  
Phosphate Buffer ◽  
Osmium Tetroxide ◽  
Uranyl Acetate ◽  
En Bloc ◽  
Thin Sections ◽  
Megakaryoblastic Leukemia ◽  
Pediatric Hematology ◽  
Transmission Electron ◽  
Microscopy Techniques

This presentation is designed to demonstrate how scanning and transmission electron microscopy techniques can be utilized to confirm or support a variety of unusual pediatric hematologic/oncologic disorders. Patients with the following diagnoses will be presented: (1) hereditary pyropoikilocytosis, (2) familial erythrophagocytic lymphohistiocytosis, (3) acute megakaryoblastic leukemia, and (4) pseudo-von Willebrand’s disease.All transmission and scanning electron microscopy samples were fixed in 2.5% glutaraldehyde, rinsed in Millonig’s phosphate buffer, and post-fixed with 1% osmium tetroxide. The transmission samples were then en bloc stained with 0.5% uranyl acetate, rinsed with Walpole ’ s non-phosphate buffer, dehydrated with graded series of ethanols and embedded with Epon 812 epoxy resin. Ultramicrotomy thin sections were stained with uranyl acetate and lead citrate and scanned using a JEOL-JEM 100C, The scanning samples were dehydrated with graded series of ethanols, critical point dried with CO2, gold-coated, and scanned using a JEOL-JSM 35. The peroxidase samples were fixed in 3% glutaraldehyde, incubated in diaminobenzidine (DAB), dehydrated with ethanol, embedded with Epon 812, and scanned without post-staining using a JEOL-JEM 100C.

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