Preparation of diagnostic specimens for transmission electron microscopy

1984 ◽  
Vol 42 ◽  
pp. 62-65
Author(s):  
Joseph M. Harb
Keyword(s):  
Diagnostic Laboratory ◽  
Specimen Handling ◽  
Simultaneous Processing ◽  
Transmission Electron ◽  
Wide Range ◽  
Negative Effect ◽  
Muscle Nerve ◽  
Embedding Medium ◽  
Technical Reliability ◽  
Selection Of

Several factors influence the selection of preparatory procedures for diagnostic TEM. These include variability of specimens, lack of accessibility to additional specimens, and the need for expeditious turn-around time and technical reliability. Specimens encountered in a diagnostic laboratory may include peripheral blood huffy coats and bone marrows, biopsies of liver, muscle, nerve, skin, kidney, lung and other organs, and a variety of tumors. It would be desirable for optimal preservation to employ a dehydration and embeddment schedule designed specifically for each specimen type, but such a practice in a diagnostic setting would seriously multiply the specimen handling steps and preclude simultaneous processing of different specimen types. Such a practice could also induce errors and increase the technical workload, which could have a negative effect on cost containment. Therefore, generalization of the preparatory schedule and selection of an embedding medium which will adequately preserve ultrastructural details for a wide range of specimens is appropriate.

scholarly journals A new method of preparing embeddment-free sections for transmission electron microscopy: applications to the cytoskeletal framework and other three-dimensional networks.

1984 ◽  
Vol 98 (5) ◽  
pp. 1878-1885 ◽  
Author(s):  
D G Capco ◽  
G Krochmalnic ◽  
S Penman
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Three Dimensional ◽  
Morphological Studies ◽  
Transmission Electron ◽  
Nonionic Detergent ◽  
Embedding Medium ◽  
Filament Networks ◽  
Free Section ◽  
Selection Of

Diethylene glycol distearate is used as a removable embedding medium to produce embeddment -free sections for transmission electron microscopy. The easily cut sections of this material float and form ribbons in a water-filled knife trough and exhibit interference colors that aid in the selection of sections of equal thickness. The images obtained with embeddment -free sections are compared with those from the more conventional epoxy-embedded sections, and illustrate that embedding medium can obscure important biological structures, especially protein filament networks. The embeddment -free section methodology is well suited for morphological studies of cytoskeletal preparations obtained by extraction of cells with nonionic detergent in cytoskeletal stabilizing medium. The embeddment -free section also serves to bridge the very different images afforded by embedded sections and unembedded whole mounts.

Intrinsic Mechanism Decreases Susceptibility ofEscherichia coli O157:H7 to Multiple Antibiotics

2004 ◽  
Vol 67 (1) ◽  
pp. 34-39 ◽  
Author(s):  
SHERENE S. GOLDING ◽  
KARL R. MATTHEWS
Keyword(s):  
Fold Increase ◽  
Ofescherichia Coli ◽  
Continuous Exposure ◽  
Agricultural Practice ◽  
Intrinsic Resistance ◽  
Intrinsic Mechanism ◽  
Wide Range ◽  
Negative Effect ◽  
Resistant Mutants ◽  
Selection Of

Chloramphenicol-resistant mutants ofEscherichia coli O157:H7 (n = 52) demonstrated multiple resistance to tetracycline, nalidixic acid, and ciprofloxacin. Approximately half of the mutants approached the clinical level of resistance to the antibiotic tetracycline. Mutants demonstrated a wide range of sensitivity to each antibiotic; for tetracycline, some isolates demonstrated a twofold increase, whereas others demonstrated a 15-fold increase in resistance. Continuous exposure to chloramphenicol did not affect the growth of mutants, suggesting that mutation does not have a negative effect on cell survival. Complementation experiments with a functional marR restored antibiotic susceptibility of selected mutants to levels similar to wild-type strains, suggesting that mar mutation was responsible for the decrease in sensitivity. The multiple antibiotic resistance (mar) operon is a global regulator controlling intrinsic resistance toward structurally and functionally unrelated antibiotics and other noxious agents. Antimicrobial use in both human and agricultural practice should be administered in a manner to prevent selection of resistant mutants.

Quantitative assessment of xylan distribution across the secondary cell wall layers of Eucalyptus dissolving pulp fibres

Holzforschung ◽  
2017 ◽  
Vol 72 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Prabashni Lekha ◽  
Tamara Bush ◽  
Norman Pammenter ◽  
Bruce Sitholè ◽  
Patricia Berjak
Keyword(s):  
Cell Wall ◽  
Secondary Cell Wall ◽  
Dissolving Pulp ◽  
Carbohydrate Binding ◽  
Transmission Electron ◽  
Wide Range ◽  
Pulp Fibres ◽  
S2 Layer ◽  
Selection Of ◽  
Specific Labelling

AbstractA quantitative method has been developed for assessment of the distribution of xylan across the secondary cell wall layers ofEucalyptusdissolving pulp fibres by means of a carbohydrate binding module (CBM),CtCBM6, in combination with transmission electron microscopy (TEM). To ensure reproducibility and to minimise non-specific labelling, various parameters were optimised, namely the size of the gold colloid marker,CtCBM6 concentration, and the selection of buffer solutions. The method was replicated on processedEucalyptusfibres containing different xylan contents. Reproducible xylan counts and distributions across the secondary cell wall layers were obtained for unbleached and bleachedEucalyptusfibres. The xylan distribution pattern across the cell wall layers S1, S2 and S3 was similar, but the S1 and S3 layers contained after bleaching more xylan than the S2 layer. The technique has a wide range of applications in basic wood research as well as in the analysis of technological processes.

Selection and Preparation of Specific Tissue Regions For Tem Using Large Epoxy-Embedded Blocks

1973 ◽  
Vol 31 ◽  
pp. 324-325 ◽  
Author(s):  
P. M. Lowrie ◽  
W. S. Tyler
Keyword(s):  
Electron Microscopy ◽  
Anatomical Structures ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Microscopic Evaluation ◽  
Embedded Blocks ◽  
Specific Tissue ◽  
Definition Of ◽  
Areas Of Interest ◽  
Selection Of

The importance of examining stained 1 to 2μ plastic sections by light microscopy has long been recognized, both for increased definition of many histologic features and for selection of specimen samples to be used in ultrastructural studies. Selection of specimens with specific orien ation relative to anatomical structures becomes of critical importance in ultrastructural investigations of organs such as the lung. The uantity of blocks necessary to locate special areas of interest by random sampling is large, however, and the method is lacking in precision. Several methods have been described for selection of specific areas for electron microscopy using light microscopic evaluation of paraffin, epoxy-infiltrated, or epoxy-embedded large blocks from which thick sections were cut. Selected areas from these thick sections were subsequently removed and re-embedded or attached to blank precasted blocks and resectioned for transmission electron microscopy (TEM).

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

Luminescence from individual dislocations in II-VI and III-V semiconductors

1991 ◽  
Vol 49 ◽  
pp. 834-835
Author(s):  
J W Steeds
Keyword(s):  
Group Iv ◽  
Luminescence Properties ◽  
Carrier Recombination ◽  
Transmission Electron ◽  
Wide Range ◽  
Basic Physics ◽  
Semiconducting Compounds ◽  
Diamond Group ◽  
Non Destructive ◽  
Technological Significance

There is a wide range of experimental results related to dislocations in diamond, group IV, II-VI, III-V semiconducting compounds, but few of these come from isolated, well-characterized individual dislocations. We are here concerned with only those results obtained in a transmission electron microscope so that the dislocations responsible were individually imaged. The luminescence properties of the dislocations were studied by cathodoluminescence performed at low temperatures (~30K) achieved by liquid helium cooling. Both spectra and monochromatic cathodoluminescence images have been obtained, in some cases as a function of temperature.There are two aspects of this work. One is mainly of technological significance. By understanding the luminescence properties of dislocations in epitaxial structures, future non-destructive evaluation will be enhanced. The second aim is to arrive at a good detailed understanding of the basic physics associated with carrier recombination near dislocations as revealed by local luminescence properties.

Applications of Transmission Electron Microscopy in the Characterization of Metal Machinability

1968 ◽  
Vol 26 ◽  
pp. 442-443 ◽  
Author(s):  
L.E. Murr ◽  
A.B. Draper
Keyword(s):  
Electron Microscopy ◽  
State Physics ◽  
Test Material ◽  
Milling Machine ◽  
Rotary Table ◽  
Solid State Physics ◽  
Materials Properties ◽  
Transmission Electron ◽  
Selection Of

The industrial characterization of the machinability of metals and alloys has always been a very arbitrarily defined property, subject to the selection of various reference or test materials; and the adoption of rather naive and misleading interpretations and standards. However, it seems reasonable to assume that with the present state of knowledge of materials properties, and the current theories of solid state physics, more basic guidelines for machinability characterization might be established on the basis of the residual machined microstructures. This approach was originally pursued by Draper; and our presentation here will simply reflect an exposition and extension of this research.The technique consists initially in the production of machined chips of a desired test material on a horizontal milling machine with the workpiece (specimen) mounted on a rotary table vice. A single cut of a specified depth is taken from the workpiece (0.25 in. wide) each at a new tool location.

Structural and electronic properties of defects in semiconductors

1995 ◽  
Vol 53 ◽  
pp. 4-5
Author(s):  
J.L. Batstone
Keyword(s):  
Semiconductor Device ◽  
Chemical Vapor ◽  
Misfit Strain ◽  
Organic Chemical ◽  
Extended Defects ◽  
Transmission Electron ◽  
Semiconductor Thin Films ◽  
Wide Range ◽  
Metal Organic ◽  
Film Substrate

The development of growth techniques such as metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy during the last fifteen years has resulted in the growth of high quality epitaxial semiconductor thin films for the semiconductor device industry. The III-V and II-VI semiconductors exhibit a wide range of fundamental band gap energies, enabling the fabrication of sophisticated optoelectronic devices such as lasers and electroluminescent displays. However, the radiative efficiency of such devices is strongly affected by the presence of optically and electrically active defects within the epitaxial layer; thus an understanding of factors influencing the defect densities is required.Extended defects such as dislocations, twins, stacking faults and grain boundaries can occur during epitaxial growth to relieve the misfit strain that builds up. Such defects can nucleate either at surfaces or thin film/substrate interfaces and the growth and nucleation events can be determined by in situ transmission electron microscopy (TEM).

Preparation of Ceramic Particulates for Transmission Electron Microscopy

1980 ◽  
Vol 38 ◽  
pp. 196-197
Author(s):  
R. J. Lauf ◽  
H. Keating
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ceramic Materials ◽  
Ion Milling ◽  
Plastic Films ◽  
Transmission Electron ◽  
Specimen Orientation ◽  
Selection Of

The preparation of fragmented or particulate ceramic materials for transmission electron microscopy (TEM) examination has traditionally been difficult, particularly if a durable, permanent specimen is desired. Furthermore, most established methods for dealing with micron- and submicron-sized samples (e.g., dispersion in plastic films) do not permit selection of orientations or ion thinning. A technique has been developed that is useful for a variety of materials, permits the selection of specimen orientation, is compatible with ion milling requirements, and produces a durable specimen that can be reexamined later if necessary.

COMBINATORIAL POLYNOMIALLY COMPUTABLE CHARACTERISTICS OF SUBSTITUTIONS AND THEIR PROPERTIES

2020 ◽  
Vol 7 (2) ◽  
pp. 34-41
Author(s):  
VLADIMIR NIKONOV ◽  
◽  
ANTON ZOBOV ◽  
Keyword(s):  
Mathematical Expectation ◽  
Point Of View ◽  
Small Range ◽  
Computational Point ◽  
Wide Range ◽  
Bijective Function ◽  
The Difference ◽  
Element Base ◽  
Selection Of

The construction and selection of a suitable bijective function, that is, substitution, is now becoming an important applied task, particularly for building block encryption systems. Many articles have suggested using different approaches to determining the quality of substitution, but most of them are highly computationally complex. The solution of this problem will significantly expand the range of methods for constructing and analyzing scheme in information protection systems. The purpose of research is to find easily measurable characteristics of substitutions, allowing to evaluate their quality, and also measures of the proximity of a particular substitutions to a random one, or its distance from it. For this purpose, several characteristics were proposed in this work: difference and polynomial, and their mathematical expectation was found, as well as variance for the difference characteristic. This allows us to make a conclusion about its quality by comparing the result of calculating the characteristic for a particular substitution with the calculated mathematical expectation. From a computational point of view, the thesises of the article are of exceptional interest due to the simplicity of the algorithm for quantifying the quality of bijective function substitutions. By its nature, the operation of calculating the difference characteristic carries out a simple summation of integer terms in a fixed and small range. Such an operation, both in the modern and in the prospective element base, is embedded in the logic of a wide range of functional elements, especially when implementing computational actions in the optical range, or on other carriers related to the field of nanotechnology.

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