bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential mass loss in biological microanalysis determined by digital image analysis of STEM images
Authors: Hurley B. J.
Published: June 2020

Quantitative x-ray microanalysis of biological specimens requires that the extent of electron beam induced mass loss in the tissue prior to and during analysis be determined. Previous studies using x-ray counting methods have determined the extent and dose dependence of mass loss in some freeze-dried tissues. This method is limited by the requirement of large scan areas to determine low dose information. The large scan areas yield mass loss values that are cell averages and do not allow determination of differential mass loss fractions between cellular organelles. Knowledge of such differential mass loss is important for example, in the determination of ionic gradients between mitochondria and adjacent myofibril space in cardiac muscle. In the work described here, digital STEM video images of cardiac muscle and salivary gland were used to quantify the extent of mass loss in specific cellular regions. Mass loss values in mitochondria and myofibril regions were compared in cardiac muscle whereas secretory granule and nuclear mass loss fractions were compared in salivary gland cells.
Damage removal following low energy ion implantation
Authors: Myers Edward R.
Published: June 2020

Ion implantation has become the most common method of doping in the semiconductor industry. Precise concentration profiles with exact spatial locations are achievable. However, direct implantation of the desired dopant does not always meet the stringent size requirements of ultra large scale integration (ULSI). Implantation of light ions, such as boron, tend to channel down open crystallographic orientations in crystalline substrates resulting in enhanced ion penetration and an extended doping tail. Channeling can be prevented by creation of an amorphous surface layer prior to the dopant implant. The amorphous layer can be created by implanting heavy isoelectronic ions, such as Ge+, or by implanting molecular dopant ions like BF2. Solid phase epitaxial (SPE) regrowth restores the crystallinity of the amorphous layer and activates the dopant. However, the ion implantation process damages the crystalline material adjacent to the amorphous- crystalline (a/c) interface.
Cross-section TEM observation of Ba2YCu3O7-x thin film on SrTiO3
Authors: Tomita Masato , Hayashi Takayoshi , Takaoka Hidetoshi , Ishii Yoshikazu , Enomoto Youichi , Murakami Toshiaki
Published: June 2020

The structure of Ba2YCu3O7-x(BYCO) has been almost completely analyzed using neutron,x-ray, and electron diffraction techniques. However, most of these analyses have studied bulk polycrystallinites or single crystals of BYCO, not the thin film structure. In this study, cross sections of thin annealed films on SrTiO3 substrate are observed using transmission electron microscopy (TEM). The crystal structure near the film/substrate interface is examined.

The samples for TEM observation were cut from the same film which showed an onset temperature of 80 K. Samples for cross-sectional TEM observation were prepared by the ordinary method without using water. Milling was performed using a 4 kV Ar+ beam at an incident angle of about 15°. Observation was performed using a JEOL JEM 4000EX microscope at an accelerating voltage of 400 kV.

A low magnification cross-sectional image of the BYCO annealed film is shown in Fig. 1. The film thickness is about 0.7 μm.
An external photographic system for electron microscopes
Authors: Guetter E. , Menzel M.
Published: June 2020

In commercial electron microscopes documentation of the electronmicroscopic image is realized by direct exposure of the photographic emulsion by the image-forming electrons. Exchange of the photographic material loads the vacuum system by gassing when brought in the vacuum. This impairs the operating vacuum, interrupts photography, and increases the danger of contamination.

These disadvantages are overcome by a photographic system outside the vacuum chamber of the electron microscope.

It requires an image transmission element which provides a vacuum-tight closure of the microscope column, and transmits the image from the vacuum at minimum loss of energy and information content. A fiber plate of 6 μm fiber diameter and a numerical aperture of 1 proved to be the best solution. In vacuo an image converter layer is provided in close contact with the fiber plate. It converts the electron image into a visible image. A high-resolution polycrystal fluorescent screen of high luminous efficiency is deposited on the fiber plate.
Calculation of structure images of crystalline defects
Authors: O'Keefe M.A. , Iijima Sumio
Published: June 2020

We have extended the multi-slice method of computating many-beam lattice images of perfect crystals to calculations for imperfect crystals using the artificial superlattice approach. Electron waves scattered from faulted regions of crystals are distributed continuously in reciprocal space, and all these waves interact dynamically with each other to give diffuse scattering patterns.

In the computation, this continuous distribution can be sampled only at a finite number of regularly spaced points in reciprocal space, and thus finer sampling gives an improved approximation. The larger cell also allows us to defocus the objective lens further before adjacent defect images overlap, producing spurious computational Fourier images. However, smaller cells allow us to sample the direct space cell more finely; since the two-dimensional arrays in our program are limited to 128X128 and the sampling interval shoud be less than 1/2Å (and preferably only 1/4Å), superlattice sizes are limited to 40 to 60Å. Apart from finding a compromis superlattice cell size, computing time must be conserved.
Computer simulation of high resolution images of crystal defects
Authors: Rez Peter , Krivanek Ondrej L.
Published: June 2020

During the last two years, the cores of several lattice defects in elemental Si and Ge have been directly imaged by high resolution electron microscopy The 3Å resolution images necessary for such work are even more sensitive to microscope defocus, astigmatism and other imaging parameters, and the specimen thickness and orientation, than the 4Å resolution images of complex oxides. Comparison of experimental results with computer-simulated images is therefore essential. The need for matching with theoretical simulations will increase for the coming generation of the 1-2Å point-to-point resolution microscopes.

The presently used image simulation programs are based on the multi-slice formulation of the dynamical scattering theory. They are very adequate for thin specimens and a few hundred beams but at larger specimen thicknesses and a greater number of beams the computation times required to simulate one image may be an hour or more.We are therefore investigating the suitability of alternative computational approximations and formalisms such as neglecting diffuse-diffuse scattering in the multi-slice method and the matrix diagonalization formulation of the dynamical scattering theory.
Characterization of neutron irradiation damage in zirconium alloys—an international “round-robin” experiment
Authors: Northwood D.O. , Gilbert R.W. , Kelly P.M. , Madden P.K. , Faulkner D. , Adamson R.B.
Published: June 2020

Over the past few years there has been disagreement between laboratories on the exact nature of the damage in irradiated zirconium alloys. The main disagreement has centred on whether or not dislocation loops with c-component Burgers' vectors are formed during the irradiation. Since the presence of c-component loops was required in one of the current theories of irradiation growth and is considered in many other models, it was desirable to clear up this point and others relating to the nature of the damage such as loop size, loop concentration and the nature of the loop population, i.e. vacancy or interstitial. To this end a ‘round-robin’ series of transmission electron microscopy (TEM) examinations of neutron irradiated zirconium alloys was organized and the results are reported herein.

The participants in the ‘round-robin’ included laboratories who had previously claimed to have seen evidence for c-component damage. The materials examined included zirconium and Zircaloy-2 irradiated at temperatures from 250-400°C, Table 1, the materials irradiated at 400°C providing samples with dislocation loops large enough to determine the interstitial/vacancy nature by inside/outside contrast techniques.
In situ TEM studies of NaCl-gas reactions
Authors: Chung T.T. , Dash J. , O'Brien R.J.
Published: June 2020

The electron microscope is an important instrument for studying the structure and morphology of particulates collected from the atmosphere, but its potential for direct observation of the interactions between atmospheric aerosols and gases has not been explored previously. A cell with thin film windows and ports to permit the passage of gases was constructed for this purpose, Fig. 1. This cell is designed for use in the tilting stage of a Hitachi HU125 TEM. The thin film windows (manufactured by E. F. Full am, Inc. (1) ) consist of a composite film of formvar and evaporated SiO on 400 mesh Cu grids.

In the first experiments with this cell, particles of NaCl were collected from a modified De Vilbiss nebulizer on the lower window of the cell and observed continuously during passage through the cell of either (1) water vapor or (2) water vapor and NO2.

The image was recorded continuously on video tape and intermittently on sheet film.
Deposited emulsion particles in the pores of aluminum oxide film
Authors: Ashida Michio , Ueda Yasukiyo
Published: June 2020

An anodic oxide film is formed on aluminum in an acidic elecrolyte during anodizing. The structure of the oxide film was observed directly by carbon replica method(l) and ultra-thin sectioning method(2). The oxide film consists of barrier layer and porous layer constructed with fine hexagonal cellular structure. The diameter of micro pores and the thickness of barrier layer depend on the applying voltage and electrolyte. Because the dimension of the pore corresponds to that of colloidal particles, many metals deposit in the pores. When the oxide film is treated as anode in emulsion of polyelectrolyte, the emulsion particles migrate onto the film and deposit on it. We investigated the behavior of the emulsion particles during electrodeposition.

Aluminum foils (99.3%) were anodized in either 0.25M oxalic acid solution at 30°C or 3M sulfuric acid solution at 20°C. After washing with distilled water, the oxide films used as anode were coated with emulsion particles by applying voltage of 200V and then they were cured at 190°C for 30 minutes.
Lorentz microscopy study of magnetic domain walls in Fe-Cr-Co alloys
Authors: Belli Yalcin
Published: June 2020

Fe-Cr-Co alloys have great technological potential to replace Alnico alloys as hard magnets. The relationship between the microstructures and the magnetic properties has been recently established for some of these alloys. The magnetic hardening has been attributed to the decomposition of the high temperature stable phase (α) into an elongated Fe-rich ferromagnetic phase (α1) and a weakly magnetic or non-magnetic Cr-rich phase (α2). The relationships between magnetic domains and domain walls and these different phases are yet to be understood. The TEM has been used to ascertain the mechanism of magnetic hardening for the first time in these alloys. The present paper describes the magnetic domain structure and the magnetization reversal processes in some of these multiphase materials. Microstructures to change properties resulting from, (i) isothermal aging, (ii) thermomagnetic treatment (TMT) and (iii) TMT + stepaging have been chosen for this investigation. The Jem-7A and Philips EM-301 transmission electron microscopes operating at 100 kV have been used for the Lorentz microscopy study of the magnetic domains and their interactions with the finely dispersed precipitate phases.
Formation of carbides by C-diffusion in Cr-Fe-Ni alloys
Authors: Peignier P. , Demel O. , Degischer H.P.
Published: June 2020

MATERIAL: Cr-Fe-Ni alloys, casted in air, treated at 1150°C, 20 mn/water quenched. Cr constant 15%, Ni range 15 to 70%, 0,011 to 0,017% C, 0,03-0,07% N, 0,22-0,54% Mn. The C-diffusion experiments were realized at 850 °C/53 h in pure argon. The carburizing profile is known from tracer experiments (1). The penetrating carbon forms carbides to be investigated.

METHODS: Optical metallography and T.E. microscopy on carbon replicas (etching agent: Br-ethanol 10%) were performed to identify the precipitates and to determine their distribution and morphology. The crystal structure was investigated by SAD using a rotation-tilt stage (± 55° tilt) : a low indexed g-vector is rotated into the tilt axis,from there the specimen is tilted to obtain the characteristic diffraction patterns of the inclusion and thus it is possible to reconstruct the reciprocal lattice. X-ray structure analysis was performed to find the exact lattice parameters and to get an indication of the amount of the different phases.
Electron microscopic examination of mast cells and nerve processes in hepatic portal areas of the rat
Authors: Dimlich R. V. W.
Published: June 2020

Neural mechanisms are important in the regulation of numerous hepatic functions including hepatic blood flow, carbohydrate metabolism and biliary flow. The innervation of the liver is species specific and in the rat, light microscopic data indicated that catecholamine and cholinergic nerves were present in portal areas. (1,2) Electron microscopic studies described the presence of nerve endings in the connective tissue adjacent to blood vessels and bile ducts as well as limiting plate hepatocytes. (2) A previous study in this laboratory reported unmyelinated nerve processes near mast cells. (3) The present study was undertaken to quantify the appearance of nerves and their relationship to mast cells in hepatic portal areas in rats.

Hepatic tissue from 8 rats was removed and fixed in 2% glutaraldehyde and 2% paraformaldehyde in a 0.1M Na cacodylate buffer (pH 7.3), postfixed in 1% osmium tetroxide, and embedded in Epon. Sections stained with uranyl acetate and lead citrate were viewed on a Philips 301 electron microscope. A minimum of 3 sections per rat and a total of 30 portal areas were analyzed.
Ultrastructural localization of protein kinase subunits in glucagon-treated rat hepatocytes applying the colloidal-gold technique
Authors: Kuettel Michael R.
Published: June 2020

The molecular mechanisms by which non-steroidal hormones regulate transcription in eukaryotes has not been elucidated. However, cyclic AMP, an important second messenger of the hormonal signal has been suggested to play a significant role in the regulation of eukaryotic gene expression (1). It has also been proposed that hormones functioning through the cAMP/adenylate cyclase system initiate a series of biochemical events in the target tissue resulting in the synthesis of new RNA and protein (2). The important link in this scheme appears to be the cAMP dependent protein kinase which may translocate from cytoplasm to nucleus following its activation by cAMP. Two types of soluble cAMP dependent protein kinases exist in mammalian tissues (type I and II). Each isozyme exists as a tetramer composed of two catalytic (C) and two regulatory (R) subunits. Binding of cAMP to the R subunit activates the C subunit according to the following stoichiometry: R2C2 + 4cAMP = R2·cAMP4 + 2C.
The cytochemical localization of glucose-6-phosphatase and catalase in cells comprising the root cap of corn
Authors: McClelen C.E.
Published: June 2020

The root cap of corn (Zea mays) is comprised of several different types of cells, each having a unique structure and function. For example, columella cells in the center of the cap are responsible for perceiving gravity. These cells subsequently differentiate into peripheral cells, which are located at the edge of the cap and function in the production and/or secretion of mucopolysaccharides (mucilage). Differences in enzymatic activity and location in cells of the root cap provide key evidence for the nature and site of the functional changes that accompany differentiation.

The cytochemical localizations of glucose-6-phosphatase (G-6-Ptase) and catalase were undertaken to define the modifications of enzyme localization associated with cellular differentiation in root caps of Zea mays. G-6-Ptase and catalase were localized using procedures described by Hall. Cytochemistry as performed in this study was consistently specific for the designated enzyme and gave precise ultrastructural localization. Enzymatic precipitate was absent in all controls. Sections were not counterstained to allow for positive identification of staining due to enzymatic activity.
Interpretation of irradiation-induced changes in electron diffractograms and images of extinction contours at low temperatures
Authors: Knapek E. , Formanek H. , Lefranc G. , Dietrich I.
Published: June 2020

A few years ago results on cryoprotection of L-valine were reported, where the values of the critical fluence De i.e, the electron exposure which decreases the intensity of the diffraction reflections by a factor e, amounted to the order of 2000 + 1000 e/nm2. In the meantime a discrepancy arose, since several groups published De values between 100 e/nm2 and 1200 e/nm2 /1 - 4/. This disagreement and particularly the wide spread of the results induced us to investigate more thoroughly the behaviour of organic crystals at very low temperatures during electron irradiation.

For this purpose large L-valine crystals with homogenuous thickness were deposited on holey carbon films, thin carbon films or Au-coated holey carbon films. These specimens were cooled down to nearly liquid helium temperature in an electron microscope with a superconducting lens system and irradiated with 200 keU-electrons. The progress of radiation damage under different preparation conditions has been observed with series of electron diffraction patterns and direct images of extinction contours.
High-performance transmission electron microscopy of cryospecimens
Authors: Hezel U. B. , Zellmann E. , Hoffmeister D.
Published: June 2020

Chemical fixation, resin embedding and subsequent staining with heavy metals can both produce artefacts and limit the resolution in the electron microscopic specimen /1-5/. The objective is thus to observe the specimens in the electron microscope in the frozen-hydrated state, the one most similar to the native state.

All preparation steps such as cryofixation, cryosectioning and cryotransfer to the cryo-transmission electron microscope (CryoTEM) should be performed below 145K /5/ in order to observe the specimen in a matrix of vitrified ice avoiding any crystallization artefacts. In the CryoTEM itself the temperature of the frozen-hydrated specimen should be kept much lower to avoid devitrification caused by the electron beam /1/. - To meet all these requirements a special cryotransfer system and cryostage for the Zeiss transmission electron microscopes have been developed /7/.
Energy-dispersive x-ray spectroscopy: A tutorial
Authors: Hall Ernest L.
Published: June 2020

The purpose of this paper is to present a tutorial review of the principles and practice of energy dispersive X-ray spectroscopy (EDXS) in the analytical electron microscope (AEM). Since this topic can only be treated here in the most cursory fashion, references which constitute a short bibliography on the subject are provided at the end of the paper. Excellent detailed summaries of the current status and future directions of EDXS in the AEM have been provided by Goldstein, Zaluzec, Williams, and Goldstein and Williams. In this paper, some of the important considerations for obtaining meaningful results from X-ray spectra will be described. Although all of the specific examples will be taken from materials science, this description applies equally to biological materials.
An ultrahigh vacuum and ultrahigh resolution transmission electron microscope
Authors: McDonald M.L. , Gibson J.M.
Published: June 2020

Interest in ultrahigh vacuum (UHV) specimen environments in the transmission electron microscope (TEM) has grown considerably in recent years. The possibility of in-situ studies of atomically clean surfaces has been demonstrated by Yagi et.al., Wilson & Petroff & others. Most designs have involved a side entry specimen holder with cryopumping in the pole piece and are not easily compatible with ultrahigh resolution(UHR) due to size and stability requirements. We have designed a differentially pumped UHV specimen chamber for the JEOL 200CX (UHRTEM). It is intended to allow examination of clean thin specimens at pressures below 10-9 torr with a point to point resolution of 2.5 Å. Provisions for in-situ heating, cooling & deposition have been made. A unique part of this design is the relatively large volume sample chamber held at UHV (figsl&2). This design allows characterization of the atmosphere to which the sample is exposed & cleaning & preparation of samples out of the pole piece which is believed to be necessary for UHRTEM. Another possibility with this design is the transfer of a sample into the TEM from other chambers by use of a transfer case without exposing the sample to an atmosphere above 10-9 torr. Extra ports have been provided to accommodate future experiments.
Analytical transmission electron microscopy of multifilamentary V3Ga superconducting wires
Authors: Pande C.S. , Smith S. , Francavilla T.L. , Gubser D.U.
Published: June 2020

High field (>10 Tesla) superconducting wires of the A15 compound V3Ga have recently been produced by a new solid state diffusion technique known as the modified jelly roll (MJR) technique which is suitable for rapid production of V3Ga composite superconducting wires. In this process vanadium is rolled into a sheet, slit in a regular pattern, expanded and then wrapped with the Cu-Ga sheet to form a billet. This billet is subsequently extruded to 1.9 cm diameter at 500°C and then drawn into wires (final diameter 0.9 mm). The wires can then be reacted typically around 600°C for about 100 hours to produce superconducting V3Ga filaments. Each wire contains about 5300 such filaments (see Figure 1). Analytical and conventional TEM has been used to characterize grain size, texture, stoichiometry and degree of order for this material.
On the dynamical extinction condition
Authors: Ling P.
Published: June 2020

The conditions for dynamical extinction have been discussed by Cowley, Moodie, Miyake, Takagi and Fujimoto and by Gjϕnner and Moodie. Ling has extended the analysis of Gjϕnnes and Moodie on the effect of axial glide plane to the dynamical extinction in crystals with diamond glide plane. The dynamical extinction condition for the (200) spot in Fd3m structure is that the projection of the center of the Ewald sphere lies on a line passing through (000) and (200) spots as shown in Fig. 1. The electron diffraction pattern of Si taken under the dynamical extinction and Bragg conditions of (200) is shown in Fig. 2. The strongly excited (200) spot can be observed in Fig. 2, which is contradicted with the dynamical extinction prediction. This observation indicates there must be some points not taken into consideration in the derivation of the dynamical extinction condition.
Analysis of transition alumina structures using HRTEM
Authors: Morrissey K. J. , Czanderna K. K. , Merrill R. P. , Carter C. B.
Published: June 2020

The transition aluminas are important materials used as catalysts, co-catalysts, catalyst supports, and adsorbents, γ-alumina is used in catalysis because it has a high surface area and an inherent defect structure. Much of the special surface chemistry is attributed to defect acid sites. These sites apparently occur during the dehydroxyilation of the oxyhydroxides which are their precursors. The structure of γ-Al2O3 is not well understood; most of the previous structure analysis has used powder x-ray diffraction. In this study high resolution transmission electron microscopy (HRTEM) and selected area diffraction (SAD) were used to investigate the structure and the defect nature of the aluminas.
Atomic-level imaging of the surface structure of Ag2O
Authors: Krakow William
Published: June 2020

In recent years electron microscopy has been used to image surfaces in both the transmission and reflection modes by many research groups. Some of this work has been performed under ultra high vacuum conditions (UHV) and apparent surface reconstructions observed. The level of resolution generally has been at least an order of magnitude worse than is necessary to visualize atoms directly and therefore the detailed atomic rearrangements of the surface are not known. The present author has achieved atomic level resolution under normal vacuum conditions of various Au surfaces. Unfortunately these samples were exposed to atmosphere and could not be cleaned in a standard high resolution electron microscope. The result obtained surfaces which were impurity stabilized and reveal the bulk lattice (1x1) type surface structures also encountered by other surface physics techniques under impure or overlayer contaminant conditions. It was therefore decided to study a system where exposure to air was unimportant by using a oxygen saturated structure, Ag2O, and seeking to find surface reconstructions, which will now be described.
Ultrastructural and metabolic effects of products of activated mononuclear leucocytes on cultured human dermal fibroblasts
Authors: Stachura I. , Pardo Matias , Worrall Jennifer , Whiteside Theresa L.
Published: June 2020

Products of antigen- or mitogen-activated mononuclear leucocytes (ML) are known to modulate fibroblast proliferation and collagen production in vitro. In tissue, ML accumulate at sites of inflammation and are probably involved in the process of fibrosis. We have established that supernatants (SN) of concanavalin A-activated ML increase synthesis of glycosaminoglycan (GAG) in human dermal fibroblast (DF) cultures). When explants of normal human skin were cultured in CMRL 1066 medium supplemented with 15% pooled human serum and containing MLSN the outgrowing DF acquired a distinctive phenotype. In comparison to control DF, the cells treated with MLSN exhibited a marked increase in the number of intracytoplasmic organelles especially dilated cisternae of RER filled with electrondense material, abundant lysosomes, prominent Golgi apparatus and bundles of microfilaments often extending beyond the cell boundaries. Cell surfaces were shaggy and floccular material accumulated in patches along the plasma membranes.
Structural changes induced by fluoride in rat bones
Authors: Reid A. D. , Grynpas M. D. , Pritzker K. P. H. , Harrison J. E.
Published: June 2020

Fluoride is an essential trace element for normal skeletal growth and maintenance. As fluoride intake can lead to increased skeletal mass, fluoride in the form of NaF is being used clinically in the treatment of osteoporosis. The mechanisms by which fluoride affects bone is poorly understood. NaF administration has been found to increase the rate of bone formation along with an increase in the number of osteoblast cells. Fluoride has been also shown to increase the crystallinity of bone apatite by substituting for hydroxylions in the apatite lattice, rendering bone mineral less soluble and more stable.

In our study we undertook to elucidate further the effects of fluoride on bone mineral. Eight mature female rats (250-300 g) were divided into control and fluoride-treated groups with 4 rats in each group. The fluoridetreated rats were given a fixed amount of supplemental NaF in their water and food: the control group was given distilled water and no supplemental fluoride. The animals were sacrificed 7 weeks later.
Scanning Electron Microscopy Study of Porous Anodic Films on Aluminum
Authors: Phillips V. A. , Meyerhoff M.
Published: June 2020

If aluminum is anodized in a bath, such as sulfuric acid, in which the anodic oxide coating has appreciable solubility, then the oxide layer may grow to a thickness of many microns. The resulting film can be regarded as consisting of two layers, a thin barrier layer adjoining the surface of. the metal, and an outer thick film containing pores. The latter convey the electrolyte to the barrier layer, permitting continued oxidation.

We have examined the structure of a number of sulfuric acid anodized films to assess the applicability of the two principal models of the pore structure. The older model represented the pores as rather regularly spaced, uniform channels running nearly normal to the oxide surface, separated by walls of amorphous alumina. Although conceived as starshaped rather than circular in cross-section, experimental evidence has pointed to the latter. In this ideal model, the porous film was made up of hexagonal cells of amorphous alumina, each containing a central pore.
The Properties and Use of a Computer Interfaced Video System for High Resolution Microscopy
Authors: Goldfarb William , Siegel Benjamin M.
Published: June 2020

Image collection from a transmission electron microscope operating at UHV throughout the column offers special problems and opportunities. Since photographic emulsion is excluded as the primary detector of electrons, a high resolution low noise slow scan video system directly interfaced to a minicomputer with disk and tape storage has been designed to do the job. The functions envisioned for the microscope requires high sensitivity, Dqe, and signal-to-noise ratio from the image collection system. Television for transmission electron microscopy has been a commercial reality for years but standard systems have resolution and signal-to-noise characteristics too limited for our application. Also, the normal TV scan rate excludes efficient computer data collection.
The Energy Dependence of Radiation Damage in 1-Valine
Authors: Howitt D. G. , Glaeser R. M. , Thomas G.
Published: June 2020

In the study of radiation sensitive materials in an electron microscope a limit to resolution is imposed when the number of electrons required to record an image is greater than the number required to destroy the specimen. This limitation is conveniently expressed in the equation due to Glaeser (1973):

where d is the size of the object detail, c the contrast of the object feature, f the detection efficiency of the recording device and Ncr the critical exposure, is the number of electrons in unit area which will destroy the specimen.
Fluorocitrate Neural Dystrophy of the Guinea Pig Cochlea
Authors: Spector G.J. , Carr C.D. , Kaufman Arenberg I. , Maisel R.H.
Published: June 2020

All studies on primary neural degeneration in the cochlea have evaluated the end stages of degeneration or the indiscriminate destruction of both sensory cells and cochlear neurons. We have developed a model which selectively simulates the dystrophic changes denoting cochlear neural degeneration while sparing the cochlear hair cells. Such a model can be used to define more precisely the mechanism of presbycusis or the hearing loss in aging man.

Twenty-two pigmented guinea pigs (200-250 gm) were perfused by the perilymphatic route as live preparations using fluorocitrate in various concentrations (15-250 ug/cc) and at different incubation times (5-150 minutes). The barium salt of DL fluorocitrate, (C6H4O7F)2Ba3, was reacted with 1.0N sulfuric acid to precipitate the barium as a sulfate. The perfusion medium was prepared, just prior to use, as follows: sodium phosphate buffer 0.2M, pH 7.4 = 9cc; fluorocitrate = 15-200 mg/cc; and sucrose = 0.2M.
The Production of Neuroaxonal Dystrophy in the Lateral Vestibular Nucleus of Rats by Centrifugation
Authors: Johnson J.E.
Published: June 2020

Very little is known about the effects of altered gravitational forces on the morphology of the central nervous system. Data so far published have been at the light microscopic level. The present abstract and corresponding article (in preparation) represent initial electron microscopic observations of changes in the lateral vestibular nuclei (VL) of rats centrifuged for varying lengths of time. Several groups of rats were employed in the study. Two groups were placed on a centrifuge (4.15 g's) at weaning and removed after 4 days. One group was conceived, born and raised on the centrifuge (4.15 g's) for 1 month. Other rats were placed on at weaning and left on for up to 21 months (2.76-4.l5 g's). All the centrifuged rats were sacrificed by aldehyde perfusion immediately after removal from the centrifuge.

In the rat lateral vestibular nucleus, some synaptic terminals contain spherical (S) vesicles and others flattened (F) vesicles.
Unlabeled Antibody Immunocytochemistry Applied to Murine Mammary Tumor Cells
Authors: Arnold Wm. J. , Russo J. , Soule H. D. , Rich M. A.
Published: June 2020

Our studies of mammary tumor virus have included the application of the unlabeled antibody enzyme method of Sternberger to mammary tumor derived mouse cells in culture and observation with an electron microscope. The method avoids the extravagance of covalent binding of indicator molecules (horseradish peroxidase) with precious antibody locator molecules by relying instead upon specific antibody-antigen linkages. Our reagents included: Primary Antibody, rabbit anti-murine mammary tumor virus (MuMTV) which was antiserum 113 AV-2; Secondary Antibody, goat anti-rabbit IgG gamma chain (Cappel Laboratories); andthe Indicator, rabbit anti-horseradish peroxidase - horseradish peroxidase complex (PAP) (Cappel Labs.). Dilutions and washes were made in 0.05 M Tris 0.15 M saline buffered to pH 7.4. Cell monolayers, after light fixation in glutaraldehyde, were incubated in place by a protocol adapted from Sternberger and Graham and Karnovsky, then embedded by our usual method for monolayers. Reagents were confined to specific areas by neoprene 0-rings (Parker Seal Co.) reducing the amount of reagent needed to 50 microliters, 1/6th of that required to wet a 35 mm petri dish.
Cytoplasmic Cylinders Associated with the Nucleus and Cell Wall of Marchantia Spermatids
Authors: Kreitner G. L.
Published: June 2020

Analysis of thin sections reveals that young spermatids of the liverwort Marchantia effect considerable thickening of their cell wall over a narrow range of spermatid development. Cells of only slightly different age can be identified by wall thickness and by their appearance in separate blocks, the cells of which are synchronous. On rare occasion in one block cytoplasmic cylinders appeared singly or in aggregates of many closely arranged, parallel cylinders (Fig. 1). Their long axes follow an oblique path through the cytoplasm, and they appear to penetrate the envelope of the nucleus at one end (Fig. 3) and merge with fibrogranular material of the spermatid wall at the other end (Fig. 4).

Cytoplasmic cylinders average about 100 nm in diameter and have been measured at 0.6 microns in length. Tangential sections following the length of a cylinder show that its margin is regularly contoured in this plane, but smooth in transection (Fig. 2).
Transmission Electron Microscopy of Endometrium in Women Bearing Progesterone- Releasing Intrauterine Devices
Authors: González-Angulo A. , Aznar-Ramos R. , Ruiz de Chavez I.
Published: June 2020

The addition of natural progesterone with a continuous daily release rate to inert intrauterine devices has resulted in a lower pregnancy rate and a reduced frequency of bleeding and expulsions. Light microscopy studies on these endometria have shown a suppressed or inactive pattern in addition to inflammatory infiltrate as well as a diffuse predecidual reaction with degenerative changes in most cases. The aim of the present study is to characterize at ultrastructural level the possible modifications seen in cell organelles in both epithelium and stroma resulting from a continuous release rate of progesterone.

Twenty endometrial biopsies were taken; ten at day 10 ± 2 and ten at 20 ± 2 days of the menstrual cycle. Proliferative endometrium disclosed a paucity of cell organelles and it was similar to what has been described for inert devices (2). Secretory endometrium disclosed accumulation of light and dark glycogen in the cytoplasm (Fig. 1).
Tube-Foot Ultrastructure of an Ophiuroid Echinoderm
Authors: Hajduk S.L.
Published: June 2020

The tube-feet of asteroids and echinoids, highly extensible tubular structures expanded distally into suckers, are important in gas exchange, locomotion, feeding and sense-reception. Their ultrastructure has been thoroughly examined. The less extensible, suckerless tube feet of ophiuroids have been shown to serve the same functions, but their ultrastructure has not been examined. I report here on ultrastructural features of the tube-feet of the ophiuroid Hemipholis elongata.

The wall of the tube-foot is continuous with the water vascular system. The lumen of the tube-foot contains the same spherical hemoglobin-containing cells found elsewhere in the water vascular system. The innermost layer of the wall is composed of flagellated, choanocyte-like cells which form cytoplasmic extensions into the cavity of the tube-foot (Figure 3). Attachment of these cytoplasmic extensions to the hemoglobin-containing cells has been observed. Septate desmosome cell junctions are frequently seen in this inner epithelial layer and less frequently in the surface epithelial layer.
Auto-Correlation Analysis of High-Resolution Electron Micrographs of Near-Amorphous Thin Films
Authors: Fan G.Y. , Cowley J.M.
Published: June 2020

Many electron micrographs of thin films of amorphous materials give the impression that small ordered regions are present (Fig. 1). However, for cases where little order exists it is difficult to decide whether small regular patches are indictions of ordering or just chance occurances. In order to quantitatively characterize the degree of local ordering of nearamorphous materials from information contained in this kind of micrographs, we have developed a new method in which 2-D auto-correlation functions are obtained from small image regions and then rotated relative to each other so that similar features coincide. By summing up of these auto-correlation functions, sane statistical information of the local orderig for the whole image is obtained.

Under certain limiting conditions, the intensity distribution of electron micrographs may be related directly to the projection of the charge or potential distribution of a thin film [1]. Then the 2-D auto-correlation function is equivalent to a 2-D form of Patterson Function (PF), well known in X-ray crystallography in that it represents a map of inter-atomic vectors [2]. Fran different area of the image, PFs may be similar but have mutual rotations so that when they are added together, the orientation information is lost; only the Radial Distribution Function (RDF) is obtained (fig. 4). It is therefore necessary to do sane kind of alignment before the summation.
Transmission Electron Microscopy of an Aluminum-Silver-Stainless Steel Solid State Bond
Authors: Carr M. J. , Shewbridge J. F. , Wilford T. O.
Published: June 2020

Strong solid state bonds are routinely produced between physical vapor deposited (PVD) silver coatings deposited on sputter cleaned surfaces of two dissimilar metal parts. The low temperature (200°C) and short time (10 min) used in the bonding cycle are advantageous from the standpoint of productivity and dimensional control. These conditions unfortunately produce no microstructural changes at or near the interface that are detectable by optical, SEM, or microprobe examination. Microstructural problems arising at these interfaces could therefore easily go undetected by these techniques. TEM analysis has not been previously applied to this problem because of the difficulty in specimen preparation. The purpose of this paper is to describe our technique for preparing specimens from solid state bonds and to present our initial observations of the microstructural details of such bonds.
Electron Energy Loss Spectroscopy in a 400kV Transmission Electron Microscope
Authors: Oikawa T. , Bando Y. , Hosoi J. , Kokubo Y. , Naruse M.
Published: June 2020

Electron energy loss spectroscopy (EELS) is a powerful technique to investigate the “electron and atom interaction in specimens.” EELS, as an elementary analysis tool, has the following advantages in a higher accelerating voltage transmission electron microscope (TEM):

1)

Multiple scattering disturbance decreases with increasing accelerating voltage, because the mean free path of plasmon scattering decreases.

2)

The signal background ratio (S/B) increases with increasing accelerating voltage, because the effective cut-off angle increases.

This report introduces our newly developed electron energy analyzer, the ASEA40, used for the JEM-4000EX 400kV TEM, and presents experimental results that verify its advantages.

Fig.1 shows the block diagram of the ASEA40 attached to the JEM-4000EX with the ASID40 and the computer of the EDS system.
A Sampling Device For Acquisition of Negatively Stained Clinical Specimens
Authors: Bozzola John J.
Published: June 2020

Transmission electron microscopists have used the negative staining technique for the rapid identification of viral particles in clinical samples for nearly forty years. Occasionally, it was the only laboratory procedure available until appropriate cultural or serological procedures were developed for the particular virus.

Specimens for negative staining may be classified as either directly collected fluids (urine, vesicle fluid, serum, cerebral spinal fluid, tears, nasal secretions, washings from various lesions or body sites), or suspensions in physiologically balanced solutions (suspensions of disrupted cells or semisolid materials as excreta or pus). The technique for specimen preparation usually consists of depositing the fluid specimen onto a coated grid followed by the application of a drop of stain. It is also possible to mix the fluid with stain prior to deposition on the grid. Most often specimens must be collected and transported some distance over variable periods of time in order to perform the procedure. In the laboratory, trained technicians process the specimens and carefully manipulate the fragile coated grids using jeweler's forceps that often become contaminated with infectious material.
Two-Dimensional Crystallization of Tetanus Toxin
Authors: Reidler Jeffry A. , Robinson John P.
Published: June 2020

We have prepared two-dimensional (2D) crystals of tetanus toxin using procedures developed by Uzgiris and Kornberg for the directed production of 2D crystals of monoclonal antibodies at an antigen-phospholipid monolayer interface. The tetanus toxin crystals were formed using a small mole fraction of the natural receptor, GT1, incorporated into phosphatidyl choline monolayers. The crystals formed at low concentration overnight. Two dimensional crystals of this type are particularly useful for structure determination using electron microscopy and computer image refinement. Three dimensional (3D) structural information can be derived from these crystals by computer reconstruction of photographs of toxin crystals taken at different tilt angles. Such 3D reconstructions may help elucidate the mechanism of entry of the enzymatic subunit of toxins into cells, particularly since these crystals form directly on a membrane interface at similar concentrations of ganglioside GT1to the natural cellular receptors.
Cytoskeletal Alterations Associated with the Progression of Neonatal Cardiac Myocytes Into Culture.
Authors: Terracio L. , Robertsson K. , Dewey A.R. , Borg T.K.
Published: June 2020

Recognition, attachment, spreading and subsequent progression of cells into culture has been studied individually but rarely as a series of complex events. Numerous studies have shown that cells can attach to a wide variety of substances and/or surfaces but only a few macromolecules initiate spreading reactions and subsequent progression into culture. Specific adhesion of cells to extracellular matrix (ECM) components has been shown to influence both the attachment process and progression into culture. The involvement of the cytoskeleton in the spreading of cells is well documented, however, in isolated myocytes, the cytoskeleton is also necessary for the mechcanical linkage of the contractile apparatus to the sarcolemma. In this study we investigated cytoskeletal reorganization associated with progression of neonatal rat cardiac myocytes into culture on ECM components.
Electrostatic optics and aberration correction in the 1940s and today
Authors: Rempfer Gertrude F.
Published: June 2020

I became involved in electron optics in early 1945, when my husband Robert and I were hired by the Farrand Optical Company. My husband had a mathematics Ph.D.; my degree was in physics. My main responsibilities were connected with the development of an electrostatic electron microscope. Fortunately, my thesis research on thermionic and field emission, in the late 1930s under the direction of Professor Joseph E. Henderson at the University of Washington, provided a foundation for dealing with electron beams, high vacuum, and high voltage.

At the Farrand Company my co-workers and I used an electron-optical bench to carry out an extensive series of tests on three-electrode electrostatic lenses, as a function of geometrical and voltage parameters. Our studies enabled us to select optimum designs for the lenses in the electron microscope. We early on discovered that, in general, electron lenses are not “thin” lenses, and that aberrations of focal point and aberrations of focal length are not the same. I found electron optics to be an intriguing blend of theory and experiment. A laboratory version of the electron microscope was built and tested, and a report was given at the December 1947 EMSA meeting. The micrograph in fig. 1 is one of several which were presented at the meeting. This micrograph also appeared on the cover of the January 1949 issue of Journal of Applied Physics. These were exciting times in electron microscopy; it seemed that almost everything that happened was new. Our opportunities to publish were limited to patents because Mr. Farrand envisaged a commercial instrument. Regrettably, a commercial version of our laboratory microscope was not produced.
Structural analysis of ω-like diffuse scattering from quenched Cr-Ti alloys
Authors: Sinkler W. , Luzzi D. E.
Published: June 2020

Incommensurate diffuse scattering is seen in electron diffraction from the quenched-in body centered cubic phase (β phase) of alloys composed of titanium or zirconium with other early transition metals. Such diffuse scattering is related to the commensurate ω phase, a high pressure equilibrium phase of pure titanium, which also forms in dilute quenched alloys after annealing. The present study concerns ω-like diffuse scattering in the quenched (β phase of the Ti-Cr system. It is shown that the diffuse scattering in concentrated alloys consists of ω diffraction maxima which have undergone ordered displacements from commensurate ω reciprocal lattice positions. The displacement magnitude increases with solute content (see figure 1). A general expression in reciprocal space for the dependence of the diffuse peak shift on (hkl)ω was found. A model based on this expression correctly predicts the location of all diffuse peaks.