Re-determination of the temperature of the coherent spinodal curve in an-Al-15 at.% Zn alloy by transmission electron microscopic and hardness investigations

Electron microscopic methods have been applied increasingly during the past fifteen years, to problems in structural molecular biology. Used in conjunction with physical chemical methods and/or Fourier methods of analysis, they constitute powerful tools for determining sizes, shapes and modes of aggregation of biopolymers with molecular weights greater than 50, 000. However, the application of the e.m. to the determination of very fine structure approaching the limit of instrumental resolving power in biological systems has not been productive, due to various difficulties such as the destructive effects of dehydration, damage to the specimen by the electron beam, and lack of adequate and specific contrast. One of the most satisfactory methods for contrasting individual macromolecules involves the deposition of heavy metal vapor upon the specimen. We have investigated this process, and present here what we believe to be the more important considerations for optimizing it. Results of the application of these methods to several biological systems including muscle proteins, fibrinogen, ribosomes and chromatin will be discussed.

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Determination of the phase structure of polymerblends by electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109604 ◽

1978 ◽

Vol 36 (1) ◽

pp. 492-493

Author(s):

Dr. G. Kaemof

Keyword(s):

Screw Extruder ◽

Electron Microscopic ◽

Thin Sections ◽

Single Screw Extruder ◽

Transmission Electron ◽

The Matrix ◽

Twin Screw ◽

Special Case ◽

Microscopic Investigations

A mixture of polycarbonate (PC) and styrene-acrylonitrile-copolymer (SAN) represents a very good example for the efficiency of electron microscopic investigations concerning the determination of optimum production procedures for high grade product properties.The following parameters have been varied:components of charge (PC : SAN 50 : 50, 60 : 40, 70 : 30), kind of compounding machine (single screw extruder, twin screw extruder, discontinuous kneader), mass-temperature (lowest and highest possible temperature).The transmission electron microscopic investigations (TEM) were carried out on ultra thin sections, the PC-phase of which was selectively etched by triethylamine.The phase transition (matrix to disperse phase) does not occur - as might be expected - at a PC to SAN ratio of 50 : 50, but at a ratio of 65 : 35. Our results show that the matrix is preferably formed by the components with the lower melting viscosity (in this special case SAN), even at concentrations of less than 50 %.

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The blister of porphyria cutanea tarda: A Scanning and Transmission Electron Microscopic study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143298 ◽

1986 ◽

Vol 44 ◽

pp. 334-335

Author(s):

Veronika Burmeister ◽

R. Swaminathan

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Basement Membrane ◽

Middle Age ◽

Porphyria Cutanea Tarda ◽

Minor Trauma ◽

Electron Microscopic ◽

Transmission Electron Microscopic Study ◽

Transmission Electron ◽

Transmission Electron Microscopic

Porphyria cutanea tarda (PCT) is a disorder of porphyrin metabolism which occurs most often during middle age. The disease is characterized by excessive production of uroporphyrin which causes photosensitivity and skin eruptions on hands and arms, due to minor trauma and exposure to sunlight. The pathology of the blister is well known, being subepidermal with epidermodermal separation, it is not always absolutely clear, whether the basal lamina is attached to the epidermis or the dermis. The purpose of our investigation was to study the attachment of the basement membrane in the blister by comparing scanning with transmission electron microscopy.

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TEM comparison of osmium vs osmium with potassium ferricyanide secondary fixatives and the impact of secondary fixative temperature on tissue preservation/contrast quality

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100167019 ◽

1996 ◽

Vol 54 ◽

pp. 910-911

Author(s):

J. W. Horn ◽

B. J. Dovey-Hartman ◽

V. P. Meador

Keyword(s):

Osmium Tetroxide ◽

Potassium Ferricyanide ◽

Electron Microscopic ◽

Transmission Electron ◽

Microscopic Evaluation ◽

Cacodylate Buffer ◽

Transmission Electron Microscopic ◽

Glutaraldehyde Solution ◽

Temperature Impact ◽

The Impact

Osmium tetroxide (OsO4) is a universally used secondary fixative for routine transmission electron microscopic evaluation of biological specimens. Use of OsO4 results in good ultrastructural preservation and electron density but several factors, such as concentration, length of exposure, and temperature, impact overall results. Potassium ferricyanide, an additive used primarily in combination with OsO4, has mainly been used to enhance the contrast of lipids, glycogen, cell membranes, and membranous organelles. The purpose of this project was to compare the secondary fixative solutions, OsO4 vs. OsO4 with potassium ferricyanide, and secondary fixative temperature for determining which combination gives optimal ultrastructural fixation and enhanced organelle staining/contrast.Fresh rat liver samples were diced to ∼1 mm3 blocks, placed into porous processing capsules/baskets, preserved in buffered 2% formaldehyde/2.5% glutaraldehyde solution, and rinsed with 0.12 M cacodylate buffer (pH 7.2). Tissue processing capsules were separated (3 capsules/secondary fixative.solution) and secondarily fixed (table) for 90 minutes. Tissues were buffer rinsed, dehydrated with ascending concentrations of ethanol solutions, infiltrated, and embedded in epoxy resin.

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Radial mass analysis of unstained STEM images of molluscan hemocyanins

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100161618 ◽

1990 ◽

Vol 48 (3) ◽

pp. 810-811

Author(s):

M.G. Hamilton ◽

T.T. Herskovits ◽

J.S. Wall

Keyword(s):

Image Analysis ◽

Hollow Cylinder ◽

Electron Micrographs ◽

Side View ◽

Mass Analysis ◽

Mass Measurements ◽

Electron Microscopic ◽

Transmission Electron ◽

Transmission Electron Microscopic ◽

Microscopic Studies

The hemocyanins of molluscs are aggregates of a cylindrical decameric subparticle that assembles into di-, tri-, tetra-, penta-, and larger multi-decameric particles with masses that are multiples of the 4.4 Md decamer. Electron micrographs of these hemocyanins typically show the particles with two profiles: circular representing the cylinder viewed from the end and rectangular representing the side-view of the hollow cylinder.The model proposed by Mellema and Klug from image analysis of a didecameric hemocyanin with the two decamers facing one another with collar (closed) ends outward fits the appearance of side-views of the negatively-stained cylinders. These authors also suggested that there might be caps at the ends. In one of a series of transmission electron microscopic studies of molluscan hemocyanins, Siezen and Van Bruggen supported the Mellema-Klug model, but stated that they had never observed a cap component. With STEM we have tested the end cap hypothesis by direct mass measurements across the end-views of unstained particles.

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Transmission Electron Microscopic Observations of Al3Li and Al3Ti Precipitation in A Rapidly Solidified Al-3Li-0.2Ti ALLOY

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600001422 ◽

1980 ◽

Vol 38 ◽

pp. 336-337

Author(s):

J. E. O’Neal ◽

K. K. Sankaran ◽

S. M. L. Sastry

Keyword(s):

Rapid Solidification ◽

Metallic Substrate ◽

Deformation Characteristics ◽

Phase Decomposition ◽

Electron Microscopic ◽

Transmission Electron ◽

Supersaturated Solid Solutions ◽

Transmission Electron Microscopic ◽

Rapidly Solidified ◽

Microstructural Homogeneity

Rapid solidification of a molten, multicomponent alloy against a metallic substrate promotes greater microstructural homogeneity and greater solid solubility of alloying elements than can be achieved by slower-cooling casting methods. The supersaturated solid solutions produced by rapid solidification can be subsequently annealed to precipitate, by controlled phase decomposition, uniform 10-100 nm precipitates or dispersoids. TEM studies were made of the precipitation of metastable Al3Li(δ’) and equilibrium AL3H phases and the deformation characteristics of a rapidly solidified Al-3Li-0.2Ti alloy.

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