bluuebunny/crossref_metadata_2025 huggingface dataset:
Fine Structure of Cardiac Muscle Cells after Injection of Normal and Thiouracil-Treated Rats with Triiodothyronine.
Authors: Nunez Eladio A. , Hagopian Martin , Greif Roger L. , Gershon Michael D.
Published: June 2020

It has been reported that morphologic changes occur in mitochondria of cardiac muscle cells following treatment with thyroid hormones (thyroxine, triiodothyronine). These observations have been used to support the view that under normal conditions, thyroid hormones control mitochondrial metabolism. We have examined the effect of triiodothyronine on the fine structure of cardiac muscle from normal and thiouracil-treated rats. Rats were given thiouracil (0.1 percent in drinking water) for 10 weeks. Normal and thiouracil-treated rats were injected with triiodothyronine (75 ug of triiodo-L-thyronine i.p. per day) for three days. The left ventricular muscle of normal rats, and rats given thiouracil, triiodothyronine or thiouracil followed by triiodothyronine was examined ultrastructurally. Morphometric analysis of electron micrographs showed that mitochondrial number was not significantly different in the four groups of animals. The fine structure of normal cardiac muscle is illustrated in figure 1. Thiouracil treatment did not alter the fine structure of cardiac muscle cells (Fig. 3).
The Network Parameters Of The T-System In Frog Muscle Measured With The High Voltage Electron Microscope.
Authors: Eisenberg Brenda R. , Peachey Lee D.
Published: June 2020

Analysis of the electrical properties of the t-system requires knowledge of the geometry of the t-system network. It is now possible to determine the network parameters experimentally by use of high voltage electron microscopy. The t-system was marked with exogenous peroxidase. Conventional methods of electron microscopy were used to fix and embed the sartorius muscle from four frogs. Transverse slices 0.5-1.0 μm thick were viewed at an accelerating voltage of 1000 kV using the JEM-1000 high voltage electron microscope at Boulder, Colorado and prints at x5000 were used for analysis.

The length of a t-branch (t) from node to node (Fig. 1a) was measured with a magnifier; at least 150 t-branches around 30 myofibrils were measured from each frog. The mean length of t is 0.90 ± 0.11 μm and the number of branches per myofibril is 5.4 ± 0.2 (mean ± SD, n = 4 frogs).
The Sarcoplasmic Reticulum of Frog Slow and Twitch Muscle Fibers as Revealed by Stereoscopic High Voltage Electron Microscopy
Authors: Bailey Craig H. , Peachey Lee D.
Published: June 2020

Our present understanding of the distribution and morphology of the sarcoplasmic reticulum (SR) in frog slow and twitch muscle fibers has been derived largely from the examination of thin sections by electron microscopy. This conventional approach to the study of an organelle as complex as the SR is limited to a degree by section thickness, and the extraction of three-dimensional information must usually be gathered from an extensive collection of two-dimensional images. The present study represents an alternative approach to the problem of investigating the three-dimensional organization of the SR by utilizing high voltage electron microscopy (HVEM) and examining stereoscopic images of selectively stained 1.0 /μm thick slices of muscle tissue.

Slow and twitch fibers from the distal fiber bundles of the frog (Rana pipiens) cruralis muscle were processed for electron microscopy according to the selective SR staining technique (DAB-H2O2 and Os-ferrocyanide) developed by Waugh. Tissue slices from 0.25 to 1.0 μm in thickness were cut on a diamond knife, mounted on grids either with or without plastic support films, and examined using the JEM-1000 microscope at the University of Colorado operating at an accelerating voltage of 1000 kV.
Lipopolysaccharide Embedded within the Exine of Pollen Grains
Authors: Rowley J. R.
Published: June 2020

Recent observations indicate that sporopollenin cannot any longer be considered as the only major component of the exine. Filaments in great numbers are exposed from exines of Lycopodium spores heated to high temperatures and sporopollenin partially dissolved. The filaments have closely spaced anionic sites whereas sporopollenin is composed only of C, H, and O and is without carboxyl groups to explain the basophilia typical of exines. The exposed filaments of Lycopodium spore exines are similar in their resistance to the organic base 2-aminoethanol, reaction to basic dyes, and in morphology to lipopolysaccharide extracted from exines of Epilgbium pollen (Rowley, abst. & oral presentation for Scand. Soc. of E.M., Umea 1973).

To isolate lipopolysaccharide (LPS), exines were dissolved in 2-aminoethanol at 130-140°C for 18 hrs. Following dialysis the residue was extracted with 45% aqueous phenol at 65-68°C. The large aggregates of LPS in water were separated from other non-dialysiable substances by ultracentrifugation.
Effects of Cytochalasin B on the Golgi Apparatus of Maize Root Cells
Authors: Mollenhauer H. H. , Morrè D. J.
Published: June 2020

Seedlings of maize (Zea mays L.) var. WF-9 X M-14 were exposed to cytochalasin B for 1/2, 1, and 2 hr at concentrations of 0, 10, and 100 ppm. The root tips were then fixed for electron microscopy and the epidermal and outer cap cells examined for changes in dictyosome form, intercisternal fibers or secretory vesicles.

Cytochalasin B did not cause significant changes in dictyosome form (Fig. 1) or intercisternal fibers. However, it did induce alterations in the distribution patterns of Golgi apparatus-derived secretory vesicles.

In epidermal and outer cap cells of the maize root, following cytochalasin B treatment, secretory vesicles accumulated within the central portions of the cytoplasm in those regions occupied by Golgi apparatus (Fig. 2, 3). Cytoplasmic regions along the cell surface were devoid of secretory vesicles, and very few vesicles were found at the cell surface (Fig. 2, 3). We interpret these findings to mean that secretory vesicles formed by the Golgi apparatus did not move to the cell surface, but accumulated at or near their sites of origin following treatment with cytochalasin B.
Ultrastructural and Biochemical Evaluation of Parathyroid Function of Pregnant Cows Administered Disodium Ethane-l-Hydroxy-1, 1-Diphosphonate (EHDP) and Fed a Low Calcium Prepartal Diet
Authors: Yarrington J.T. , Capen C.C. , Black H.E. , Re R. , Potts J.T. , Geho W.B.
Published: June 2020

EHDP is a synthetic analogue of pyrophosphate and a potent inhibitor of bone resorption. The objective of this investigation was to evaluate the effects of EHDP on the ultrastructure and function of parathyroid glands stimulated by feeding a low calcium diet to pregnant cows.

Two groups of 3 pregnant cows each were fed a low calcium (5 gm/day) diet supplemented with phosphorus (25 gm/day) for approximately 70 days prepartum and up to 2 days postpartum. Cows of one group received a daily subcutaneous injection of EHDP (4 mg/kg/day). Cows of the second group received no EHDP. At parturition cows fed the low calcium diet remained clinically normal and had serum calcium and phosphorus values of 8.05 and 4.3 mg/100 ml, respectively (Fig. 1). EHDP-treated cows developed hypocalcemia (5.44 mg/100 ml), hypophosphatemia (1.49 mg/100 ml), and clinical signs pathogonomic for parturient paresis. Plasma immunoreactive parathyroid hormone (iPTH) levels were as high or higher both prepartum and postpartum than in cows only fed the low calcium diet.
Electron Microscopic Examination of DNA in an Alkaline Sucrose Gradient
Authors: Garner W. D. , Nordquist R. E. , Bottomley R. H. , Hawrylko J. M.
Published: June 2020

The technique of lysing cells on top of an alkaline sucrose gradient prior to sedimentation was first designed to examine single stranded DNA from protoplasts. The lysis of mammalian cells and sedimentation of the released DNA has not been examined thoroughly by EM. The present work describes the ultrastructural characteristics of DNA species found after whole cell lysing and sedimentation of the DNA through an alkaline sucrose gradient.

The DNA of H4-II-E rat hepatoma tissue culture cells was prelabelled with H3TdR (luci/ml) for 18 to 24 hours prior to lysis. Cells were layered into a lysing layer (0.1 M EDTA and 0.5 N NaOH, pH 13.25) on top of a 5-202or 5-25% alkaline sucrose gradient (0.01 M EDTA, 0.1 N NaOH and 0.9 M NaCl). After centrifugation the gradients were fractionated from the bottom. The fractions containing the majority of H3TdR were applied directly on grids at pH 8.5 or 12. Samples were stained with uranyl acetate.
A Modified Technic of Staining Elastic Tissue for Electron Microscopic Study
Authors: Nordquist J.A. , Chrysant K. , Mandal A.K.
Published: June 2020

By electron microscopy elastic tissue appear electrolucent in osmium fixed unstained grids as well as grids stained with uranyl acetate and lead citrate (UA + LC). Albert and Fleischer have studied aorta of mice with metalloporphyrins imparting conspicuous electron density to the elastic tissue. We are reporting here a modified method of electron microscopic (EM) study of the elastic tissue using metalloporhyrin, silver tetraphenyl porphyrin sulfonate (STPPS).

We have studied the renal arterioles of rats and human in normal and diseased states. Elastic tissue of the aorta from young normal rat served as control for this study. Renal and aortic tissues were fixed in 4 percent glutaraldehyde, post fixed in 1 percent osmium tetroxide and embedded in spurr (blocks). From the blocks of renal tissue, 0.5 μ sections were cut, stained with methylene blue and azure II and studied by light microscopy.
Ultrastructure of Nocardiae andMycobacterium RhodochrousMicroorganisms as Observed by Negative Staining and Freeze-Etching Techniques
Authors: Serrano J.A. , Serrano Anna A.
Published: June 2020

The cell envelope and structural aspects of cytoplasmic organization of Nocardiae andM. rhodochrousmicroorganisms were exmined with negative staining and freeze-etching techniques. Specimens examined wereNocardia asteroidesVAC 330 and ATCC 14759,N. corynebacterioides,N. erythropolisATCC 4277,N. canicruriaATCC 11045 andN. salmonicolorNCIB 9701. The latter four microorganisms are related to theNocardiaspecies, but belong to the "rhodochrous" microorganisms complex. The organisms were cultured on yeast-extract agar (Difco) for 48 hr at 30C. Cells were suspended in distilled water and collected by centrifugation. Negative staining was performed with 2% Na-phosphotungstic acid containing 0.005% glycerol, pH 7.5. Freeze-etching of whole cells was conducted in a Balzers BA502 by the Moor technique. Prior to Freeze-etching, the cells were treated by one of the following procedures: a) Fixation in 2% glutaraldehyde, b) Fixation in 2% glutaraldehyde and 20% glycerol, c) Suspension in distilled water, or d) Suspension in 20% glycerol.
Electron Microscopy of Antarctic Soils: Visualization of Bound Micro-Organisms
Authors: Uydess I. L. , Rice C. W. , Hempfling W. P.
Published: June 2020

During Professor Wolf Vishniac's final journey to the “Dry Valleys” region of South Victorialand, Antarctica, he and Professor Zeddie Bowen conducted a number of experiments designed to re-examine claims of sterile or “abiotic” soils made by other investigators visiting these same regions. In addition to “labeled-release” experiments in which C14-labeled amino acids were inoculated into the soil, sterile carbon and collodion coated EM grids mounted on glass slides were implanted into the ground at geographically distinct sites. The slides were allowed to incubatein situfor a period of 4-5 weeks during which time the typical diurnal soil temperature ranged between -10° and 0°C. The slides were then carefully collected so as not to disturb attached soil particles and sealed within screw-cap containers filled with a 1.5% glutaraldehyde-phosphate buffered saline solution. Bulk soil samples were also collected aseptically from each station for examination in the laboratory.
The Effect of Temperature on Coronavirus Replication
Authors: Jamison R. M. , Cowley L. H.
Published: June 2020

Monolayers of human foreskin fibroblast cells were infected with a high input multiplicity of coronavirus 229-E. Virus was allowed to adsorb to the cells for 2 hours at 37°C. After this interval, one series of cell monolayers was covered with Eagle's minimal essential medium with 2% bovine serum warmed to 33°C and incubated in an atmosphere of 5% CO2 at 33°C. Another cell monolayer series was covered with the same medium at 37°C and incubated in an atmosphere of 5% CO2 at 37°C. At appropriate intervals, cultures were switched from 33°C to 37°C and incubated for a total of 24 hours post-inoculation. After incubation, all cultures were harvested for titration of infectious virus or electron microscopy.

The monolayers for electron microscopy were fixed in 6% glutaraldehyde, post-fixed in 2% OsO4 in Clark's buffer, dehydrated in an ethanol series, and embedded in Epon 812. Ultra-thin sections were prepared and double stained with lead citrate and uranyl acetate.
Development of Methodology for Low Exposure, High Resolution Electron Microscopy of Biological Specimens
Authors: Ai-Ming Kuo Ivy , Glaeser Robert M.
Published: June 2020

Specimen damage in the electron microscope due to the inelastic scattering of the incident electrons is one limitation to obtaining high resolution image data of biological specimens. For most organic molecules, when the electron exposure reaches 10-3 Coulomb/cm2, further observation will provide no information concerning the original structure. Therefore, in order to obtain high resolution data, the exposure must not exceed this value. At this exposure, the resulting image will be a statistically noisy one. In our work, we investigated the feasibility of improving the signal to noise ratio in the image of a periodic specimen, by spatially averaging the statistically noisy images of all the unit cells.

Using a carbon replica of an optical diffraction cross grating(54800 lines/ inch) as our test specimen, the statistically noisy image was recorded with an image intensifier at the magnification of xl600 and at the exposure of 3xl0-4electron/ μm2 on the image plane (Fig. 1a).
Experimental Determination of the Effective Resolution Limit in Thick Specimens at High Voltages
Authors: Fotino Mircea
Published: June 2020

The use of thick specimens (0.5 μm to 5.0 μm or more) is one of the most resourceful applications of high-voltage electron microscopy in biological research. However, the energy loss experienced by the electron beam in the specimen results in chromatic aberration and thus in a deterioration of the effective resolving power. This sets a limit to the maximum usable specimen thickness when investigating structures requiring a certain resolution level.

An experimental approach is here described in which the deterioration of the resolving power as a function of specimen thickness is determined. In a manner similar to the Rayleigh criterion in which two image points are considered resolved at the resolution limit when their profiles overlap such that the minimum of one coincides with the maximum of the other, the resolution attainable in thick sections can be measured by the distance from minimum to maximum (or, equivalently, from 10% to 90% maximum) of the broadened profile of a well-defined step-like object placed on the specimen.
Forensic Identifications Aided by Scanning Electron Microscopy of Silicone-Epoxy Microreplicas of Calcified and Cornified Structures
Authors: Sognnaes R.F.
Published: June 2020

Sufficient experience has been gained during the past five years to suggest an extended application of microreplication and scanning electron microscopy to problems of forensic science. The author's research was originally initiated with a view to develop a non-destructive method for identification of materials that went into objects of art, notably ivory and ivories. This was followed by a very specific application to the identification and duplication of the kinds of materials from animal teeth and tusks which two centuries ago went into the fabrication of the ivory dentures of George Washington. Subsequently it became apparent that a similar method of microreplication and SEM examination offered promise for a whole series of problems pertinent to art, technology and science. Furthermore, what began primarily as an application to solid substances has turned out to be similarly applicable to soft tissue surfaces such as mucous membranes and skin, even in cases of acute, chronic and precancerous epithelial surface changes, and to post-mortem identification of specific structures pertinent to forensic science.
An Electron Microscopy Study of the Icosahedral Phase in the Aluminum-Manganese System
Authors: Gronsky R. , Krishnan K.M. , Tanner L.E.
Published: June 2020

One of the most interesting structures to evolve from rapid solidification processing (RSP) methods is the solid metallic phase of the Al-Mn system first reported by Shechtman et al to have icosahedral symmetry. With six 5-fold rotational axes, an icosahedron defies classification as a crystallographic point lattice: it simply has no translational symmetry. Earlier work by Levine and Steinhardt showed that “quasicrystals” with 5-fold axes could be defined by extension of the Penrose tiling idea to three dimensions. These results and their recent history prompted the present attempt at structural analysis of this novel solid by a combination of convergent beam electron diffraction (CBED) and phase contrast imaging. Specimens of 74.7 at % A1 and 25.3 at % Mn were prepared by arc melting and splat quenching (hammer and anvil) followed by jet electropolishing in a nitric acid-methanol electrolyte. They were examined in both the JEM 200CX analytical electron microscope and the JEM ARM 1000 atomic resolution microscope at the National Center for Electron Microscopy.
Phase Separation in Shock Consolidated Amorphous Powder
Authors: Thadhani Naresh , Mutz Andrew H. , Vreeland T.
Published: June 2020

During shock-wave consolidation of irregularly shaped (≌50 μm diameter) Marko-met 1064 powder (Ni55.8Mo25.7Cr9.7B8.8), obtained from melt-spun ribbon, the shock energy is preferentially input at particle surfaces. Heat flow to particle interiors is sufficiently rapid to quench melted regions and form the amorphous phase at shock energies less than about 400 kJ/kg.

Amorphous powder was rolled between two 100 μm thick sheets. Discs cut from the composite strip and sections of a consolidated sample (shock energy ≌325 kJ/kg) were electrolytically jet thinned (at -25°C and -50°C) for TEM examination in a Philips EM 420 TEM/STEM.

Figure 1 is a stereo pair taken at an interparticle melted and resolidified region in the compacted powder specimen. The microstructure exhibits a dispersion of fine amorphous spherical phase (diameter ≌0.01 to 0.08 μm), randomly distributed in a continuous amorphous matrix.
Precipitation and Recovery Near Interparticle Regions In Explosively Consolidated 304 Stainless Steel Rapidly Solidified Powders
Authors: Schoenlein L. H. , Korth G. E. , Flinn J. E.
Published: June 2020

Rapid solidification often produces new and unique alloy microstructures. Retention of these microstructures may be accomplished by dynamic consolidation, the bulk temperature rise generated by this technique is quite low. However, at near-surface regions of powder particles the temperature rise can be substantial and may cause extensive recovery, recrystallization or remelting of these areas.

Examination of explosively-consolidated 304 stainless steel powders produced by dissolved gas atomization was performed by TEM. Particle interiors contained copious dislocations, twins and stacking faults, typical of shock-hardened materials. Some interparticle regions (Figure 1) contained few structural defects, apart from a network of low angle boundaries, indicating that extensive recovery occurred. The extent of these areas is typically ∼5 μm and the average subgrain is ∼0.5 μm in diameter. Precipitation also occurred in these areas, as discussed below, but was not observed in the particle interiors.
Identification of Metastable Phases Using Convergent Beam Electron Diffraction
Authors: Fraser Hamish L.
Published: June 2020

The use of convergent beam electron diffraction in the characterization of microstructures of rapidly solidified materials is described. In view of the imposed length restrictions of this paper, one example of metastable phase identification is given. At the meeting, the critical factors involved in this type of analysis will be reviewed.

The example given here is taken from a study of melt-spinning of Al-Ge alloys. In an Al-36Ge (atomic %) alloy, the type of microstructure observed in melt-spun ribbons is shown in fig. 1. A dendritic structure is seen to be surrounded by either an interdendritic second phase or a eutectic mixture. Selected area diffraction patterns obtained from this primary dendritic phase could not be indexed as either α-Al or β-Ge; since the phase diagram indicates that only these latter two solid phases are expected to be present in alloys of this composition, it is concluded that this is a metastable crystalline phase.
Failure of the Conservation of Flux in the Dynamical Theory of the Electron Diffraction
Authors: Kim H. S. , Sheinin S.S.
Published: June 2020

It is widely believed that flux is conserved in the dynamical theory of electron diffraction. Conservation of flux requires that

where ϕg is the amplitude of a diffraction beam and the sum is over all diffracted beams. (1) is valid if the crystal is assumed to be non-absorbing and if reflected waves are neglected. It can also be shown that (1) only holds if the eigenvectors of the dynamical matrix are orthogonal. Orthogonality of these eigenvectors is, however, only obtained when certain approximations and assumptions are made including, for example, the column approximation and the assumption of symmetrical Laue diffraction conditions.

In order to see the possible effects of relaxing these assumptions and approximations on conservation of flux, consider the expression for diffracted beam amplitude in non-symmetrical Laue case

where the summation is over all Bloch waves excited in the crystal.
Small-Angle Electron Scattering (SAES) of Polymers
Authors: Oralor Ralph , Lloyd Pamela , Kumar Satish , Adams W. W.
Published: June 2020

Small angle electron scattering (SAES) has been used to study structural features of up to several thousand angstroms in polymers, as well as in metals. SAES may be done either in (a) long camera mode by switching off the objective lens current or in (b) selected area diffraction mode. In the first case very high camera lengths (up to 7Ømeters on JEOL 1Ø ØCX) and high angular resolution can be obtained, while in the second case smaller camera lengths (approximately up to 3.6 meters on JEOL 1Ø ØCX) and lower angular resolution is obtainable. We conducted our SAES studies on JEOL 1ØØCX which can be switched to either mode with a push button as a standard feature.
The Mechanism of Gunshot Residue Deposition And Its Probing Characteristics to Reconstruct Shootings
Authors: Basu S.
Published: June 2020

Gunshot residue (GSR) studies by glue-lift were conducted to determine the mechanism of GSR deposition and its probing characteristics that had been essential to reconstruction of shootings in self-inflicted deaths, and have been immensely useful to interpretation of the GSR distribution on a suspect's or victim's hands.

Unlike many solid vapors that grow as various forms of crystals, GSR particles form mainly as spheroids (diameter mainly 0.5-55 μm, Fig.1) by solidification of lead, antimony and barium-containing vapors of melted primer when a bullet is discharged from its cartridge with a firearm. The molten condensate morphologies of GSR when combined with the elemental composition (Pb, Sb, Ba), makes GSR quite distinct from many environmental and occupational particulates, which may contain one or more elements of GSR.
An EELS Acquisition Peripheral For A Superminicomputer
Authors: Kopf D. A.
Published: June 2020

alysis of radiation-sensitive specimens is to relate the elemental information obtained from the specimen to that of the unirradiated material. One method is to record many low dose spectra from an area, perform elemental analysis on running averages of the spectra, and extrapolate the curves for each element to zero dose. A superminicomputer is best suited for processing the large amounts of data involved. While a commercial EELS acquisition system could be used to acquire the data, for later transfer to a larger machine, this procedure is cumbersome and involves a great deal of record keeping. The actual rate of data generation is slow enough (typically A Kbytes in 10 seconds) to permit the use of a medium-speed serial I/O channel for the transfer of spectra to a remote large computer as they are acquired. A multichannel analyzer peripheral has been built from off-the-shelf components to acquire the spectra and pass them along to the remote host.
Preparation of TEM Specimens From Highly Radioactive Materials
Authors: McCarthy J. M. , Thomas L. E.
Published: June 2020

Intense radioactivity from nuclear materials such as irradiated UO2 and high-level waste glass often makes it impractical to prepare specimens of these materials for transmission electron microscopy. This paper describes a technique that yields ion-milled TEM specimens of reasonably low total activity from highly radioactive materials. Finished specimens each consist of a 3 mm diameter annular support ring that contains a small particle of sample, typically 50 to 300 μm in diameter and 5 to 10 μm in thickness, in epoxy. Although the application to nuclear materials is highly specialized, the basic preparation method requires only readily obtained materials, the simple grinding jig shown in Fig. 1 and an ion micromill for final specimen thinning.

The specimen preparation procedure is as follows: A 3 mm diameter washer, 0.15 mm in thickness with a 0.5 mm central hole, is placed over a 50 to 300 μm diameter particle on Parafilnn and the resulting well containing the particle is filled with epoxy.
The Spinel/Alumina Phase Boundary
Authors: Kouh Y.M. , Carter C.B. , Schmalzried H.
Published: June 2020

The formation of spinel during solid-state reactions between two oxides of the type A0 (e.g. Mg0) and B203 (e.g. A1203), has been extensively studied both from a theoretical viewpoint and an experimental one. The present paper will illustrate the structural aspects of the study of the spinel/sesquioxide interface. It has recently been shown by Carter and Schmalzried, that, when Co0 and A1203 react to form Co-Al spinel, the {111} oxygen planes in the spinel do not lie parallel to the (0001) oxygen planes in the parent alumina even though the oxygen ions are almost close-packed in both planes. The small rotation which is present implies that the mechanism whereby the alumina is transformed to spinel is not simply the glide of either isolated, or bundles of, Shockley partial-like transformation dislocations as had previously been assumed, but rather involves a new defect which causes a rotation of the oxygen sublattice.
Silicon Carbide Whiskers and the VLS Mechanism
Authors: Nutt S.R. , Carpenter R.W.
Published: June 2020

Silicon carbide whiskers can be grown by pyrolysis of silica and cellulose derived from rice hulls. Whiskers grown by this process are useful as composite reinforcements in a wide range of matrix materials. Due to the scarcity of published information regarding the crystal growth mechanism, research was devoted to analysis of inclusions and defects in the whiskers. Most SiC whiskers exhibited microinclusions (<10nm in size) confined to a central core region (Fig. 1). The distribution implies a two-stage growth process in which the core region grows in the first stage, followed by lateral growth in the second stage. An HREM image of a single twinned inclusion is shown in Fig. 2. The whisker orientation is [0001] and the inclusion exhibits crossed 0.45nm lattice fringes running parallel to type II prism planes in the SiC lattice. The lattice fringes often did not span the entire inclusion diameter, and radiation damage to the inclusion was observed with increasing dose using a 200 kV electron beam.
The Observation Of Mg)-Al Interface By Hrem and Microdiffraction
Authors: Zhang S.Y. , Cowley J.M.
Published: June 2020

The combination of high resolution electron microscopy (HREM) and nanodiffraction techniques provided a powerful means for characterizing many of the interface structures which are of fundamental importance in materials science. In this work the interface structure between magnesium oxide and aluminum has been examined by HREM (with JEM-200CX) and nanodiffraction (with HB-5). The interfaces were formed by evaporating Al on freshly prepared cubic MgO smoke crystals under various vacuum conditions, at 10 -4, 10-5 10-6 and 10-7 torr. The Al layers on the MgO (001) surface are about 100Å thick. TEM observations were performed with the incident beam along the MgO [100] direction so that the interface could be revealed clearly. The nanodiffraction patterns were obtained with the electron beam of 15Å diameter parallel to the interface.
Segregation to Boundaries in an Antimony-Containing Stainless Steel
Authors: Kenik Edward A.
Published: June 2020

The mechanical strength and local chemical properties of alloys are often determined by the presence of grain boundaries in the material. Degradation of these properties is often associated with segregation of arsenic, phosphorus, and other elements to the boundaries. Though Auger spectroscopy is often employed to study the segregation, some alloys cannot be fractured inter- granularly in situ and thus cannot be studied in this fashion. Such is the case for a 16 at. % Cr, 14 at. % Ni stainless steel containing ∼0.46 at. % Sb. Relative to the antimony-free material, the presence of antimony results in a threefold decrease in the fracture elongation and a threefold increase in the density of intergranular cracks formed during creep deformation.
Electron Beam Induced Desorption: W on WO3
Authors: Marks L.D. , Petford A.K. , O'Keefe M.
Published: June 2020

We report here direct observation within an HREM of an electron beam induced desorption process by the Knotek-Feibelman or KF mechanism [1]. Results were obtained for both ground WO3 crystals and WO3 smoke, in both cases supported on holey carbon films and examined in a JEOL 200CX. The results are shown in Figures 1-4, the main features of which are:

1)

Formation of at least 2-3 layers of the metal epitaxed in the relationship W(110)//WO3(100), W[001]//WO3[001], a near coincident site epitaxy [2] with 6 WO3(100) matching 10 W(110).

2)

No evidence of a W03-x or layer near the surface, ruling out thermal decomposition mechanisms.

3)

A fairly uniform coverage indicating that the metal wets the ceramic surface.
The Microstructual Characterization of Boron Ion Implanted Silicon During Amorphization Process
Authors: Shih Yih-Cheng , Washburn Jack
Published: June 2020

Two amorphization models, heterogeneous and homogeneous nucleation have been used to describe heavy ion implantation at low temperature and light ion implantation at high temperature by many authors. However, the amorphization mechanism for light ion damage is still unclear. Cross section views of the amorphous-crystalline transition region afford a continuous picture of the crystalline to amorphous transformation process. In this work, high resolution cross-section TEM has been used to clarify the amorphization mechanism for silicon implanted with Boron ions at various temperatures and dose rates.

A cross section view is shown in Fig. 1, of silicon implanted with 1x1016/cm2 Boron ions at room temperature and 80 KeV energy. It shows that small spots first gather around near the depth of peak damage (∼2300A below the surface). High resolution images of these spots reveals that they are damage zones losing periodic atom arrangement (Fig. 2). The Electron Paramagnetic Resonance Spectrum from the same specimen contains an isotropic amorphous peak.
Complementary Z-Contrast Imaging and Digital Image Processing
Authors: Colonna K. N. , Oliphant G.
Published: June 2020

Harmonious use of Z-contrast imaging and digital image processing as an analytical imaging tool was developed and demonstrated in studying the elemental constitution of human and maturing rabbit spermatozoa. Due to its analog origin (Fig. 1), the Z-contrast image offers information unique to the science of biological imaging. Despite the information and distinct advantages it offers, the potential of Z-contrast imaging is extremely limited without the application of techniques of digital image processing. For the first time in biological imaging, this study demonstrates the tremendous potential involved in the complementary use of Z-contrast imaging and digital image processing.

Imaging in the Z-contrast mode is powerful for three distinct reasons, the first of which involves tissue preparation. It affords biologists the opportunity to visualize biological tissue without the use of heavy metal fixatives and stains. For years biologists have used heavy metal components to compensate for the limited electron scattering properties of biological tissue.
Cross-Sectional Reconstructions of Sickle Cell Hemoglobin Macrofibers.
Authors: Carragher Bridget , Bluemke David A. , Frantz Cathy E. , Potel Michael J.
Published: June 2020

We have succeeded in performing two-dimensional cross sectional image reconstructions of sickle cell hemoglobin (HbS) macrofibers. Macrofibers are long helical structures which are intermediates in the crystallization of deoxygenated sickle cell hemoglobin at low pH. Earlier work has established that macrofibers are aggregates of Wishner-Love double strands which consist of 2 half-staggered HbS molecules repeating every 64 A in the axial direction. Thin sections of embedded aggregating macrofiber cross sections reveal a dumbbell like pattern of double strands (Figure 2a,b) that is similar to the a-axis projection of the crystal structure. Approximately 5 rows with 10 double strands per row were identified in the cross section, but structural features in the thin sections were obscured by an approximately 15 degree rotational blur due to the finite thickness (400 A) of the helical section, the ill defined boundaries of the section due to uneven staining, and apparent particle damage. These structural features have now been resolved in reconstructed cross sections obtained using a real space filtered back projection algorithm.
HVEM and Computer Graphics Study of the Polarization of Cells Migrating Through Tissue
Authors: Parsons Donald F. , Marko Michael , Radermacher Michael , Frank Joachim
Published: June 2020

Study of Individual cells migrating through tissue is often carried out in thin preparations by light microcsopy, followed by fixation and Identification of the same cells by electron microscopy. This technique Is not applicable to the common situation of cells moving through bulk tissue. We show that cells migrating through tissue can assume complex shapes and distributions of organelles which change markedly between adjacent thick sections. Thus, a complete set of serial sections Is necessary to properly assess the structure of these cells. HVEM of serial thick sections also facilitates Identification of the cell types Involved and decreases by up to 30 times the number of sections required by conventional EM. Computer graphics appears to be the most versatile way to summarize and display the structural Information so obtained.
Thermal Aging Of Primary Coolant Pipe Steel
Authors: Miller M. K. , Bentley J. , Brenner S. S. , Spitznagel J. A.
Published: June 2020

The long term mechanical integrity of the pipes used to carry the primary cooling water in a pressurized water nuclear reactor is of the utmost importance for safe operation. A combined atom probe field-ion microscopy (APFIM) and transmission electron microscopy (TEM) study was performed to characterize the microstructure of this cast stainless steel and to determine the changes that occur during long-term low-temperature thermal aging.

The material used in this investigation was a commercial CF 8 type stainless steel with a bulk chemical composition as given in Table 1. The steel was examined in the as-cast, unaged condition and also after aging for 7500 h at 673K. This temperature is 100K higher than the normal service temperature and was chosen to accelerate the microstructural changes that may occur during service. As these pipes are external to the reactor they are not exposed to any significant radiation that may influence the aging behavior.
TEM Observations of Vanadium Carbide Reversion in an HSLA Steel
Authors: Locci I. E.
Published: June 2020

Microalloy precipitates in HSLA steels have relatively high equilibrium solubility temperatures. Being equilibrium phases, they are not normally associated with precipitate reversion processes. However, a recent observation has indicated that VC precipitate reversion may occur when HSLA steels are subjected to rapid heat treatment cycles. This investigation sought to determine if VC reversion occurs during rapid austenitization heat treatment cycles applied to a.14 wt% C,.48 wt% Mn and.49 wt% V HSLA steel.

As-hot-rolled strips of the alloy were cut into sections VL cm by ∼0.5 cm thick. The equilibrium solubility temperature of VC in this alloy is 1037° C. Samples were initially solution treated at 1150°C for 1/2 hour, then quenched in iced brine solution to produce low carbon martensite.
Micro Beam Orientation Determinations in Highly Deformed Cu - 12.5% Ni Alloy
Authors: Caceres P.G. , Garwood R.D.
Published: June 2020

Convergent beam microdiffraction (CBD) techniques have been used to determine changes in orientation along and across subs truetural regions such as microbands, shear bands, crystallites, etc., in a heavily cold rolled Cu - 12.5% Ni alloy of high purity. The investigation is an extension of similar studies on copper and alpha brass (see eg. 1, 2 and 3).

Pole figures and inverse pole figures determined by x-ray diffraction techniques have shown (see 4 and 5) that this alloy develops a copper-type deformation texture, although, more slowly than the pure metal since a substantial increase of the 422 reflection, arising from a (112) [111] end orientation, occurs only at deformations greater than 90% (ε ∼2.30).
High-Resolution STEM Characterisation of Discontinuous Precipitate Products in Aluminum-Zinc
Authors: Solórzano G.
Published: June 2020

Discontinuous precipitation is an interface diffusion-controlled transformation resulting from the decomposition of a supersaturated parent phase α° to yield generally a lamellar second phase 8 and a less-supersaturated matrix α'. The main transformation interface is therefore a grain boundary which acts as a fast diffusion path, enabling the required composition to change at temperatures too low for appreciable volume diffusion. The practical importance of this transformation, present in a large number of alloy systems, is related to the degradation of precipitation hardening microstructures, wherein an otherwise long lived microstructure is discontinuously coarsened by the sweeping grain boundaries.

The Kinetic and thermodynamical aspects of the steady state transformation has been Know, in theory, for many years. The theory predicts that the grain boundary-reaction front is capable of supporting a composition difference across it and a composition gradient along it.
Titanium-Suicide Contacts on GaAs
Authors: Liliental Z. , Wakita A. , Kocot C. , Washburn J. , Gronsky R.
Published: June 2020

Successful use of titanium silicides as contacts on Si suggested the possibility of their application as Schottky contacts on GaAs. One composition of Ti:Si with the ratio 1:3 annealed for 5 sec at 875°C was found to result in good Schottky contacts. The barrier height and ideality factor were 0.8 eV and 1.15, respectively. The same heat treatment procedure for the composition of Ti:Si 1:2 did not give satisfactory electrical parameters.

Cross section samples were prepared from these contacts for both compositions and were examined in a JEOL 200 CX electron microscope. Energy dispersive X-ray (EDX) and electron energy loss spectra (EELS) were taken using a Phillips 400 FEG electron microscope at 100 KV accelerating voltage.

As-deposited structures with Ti:Si ratios 1:2 and 1:3 consisted of four alternate Ti and Si layers with different thicknesses. The interface of the first Ti layer with GaAs was very flat and abrupt for both compositions.
Electron Microscopy of Barium-Promoted Copper Chromite
Authors: Hall J. B. , Kouba J. K.
Published: June 2020

Copper chromite was reported as an effective catalyst for the hydrogenation of esters to alcohols by Homer Adkins in 1931, and it still remains the catalyst of choice for this reaction. Its most common commercial application is in the hydrogenation of fatty esters to detergent range linear alcohols. Typical reaction conditions are relatively severe: 200-250°C and 2000-4000 psig hydrogen. Barium is often used as a promoter and such a catalyst is prepared by codeposition of barium and copper chromates followed by calcination to the mixed chromite. The catalyst is usually activated by reduction with hydrogen which is believed to generate highly dispersed copper metal. The barium supposedly retards overreduction of the catalyst and ameliorates sulfate poisoning.

Knowledge of the distribution and association of the Ba, Cu, and Cr catalyst components is important in understanding its function and in the design of better catalysts.
Microanalysis of Radiation-Sensitive Semiconductor Interfaces
Authors: O.L. Krivanek  , Liliental Z.
Published: June 2020

Owing to the success of high resolution electron microscopy (HREM), the structure of the most important semiconductor interfaces is now relatively well known on a scale of about 0.3nm. What is frequently missing, however, is information on the chemical composition on a similar scale.

The spatial resolution of conventional depth-profiling, broad-beam techniques (Auger, ESCA, ion scattering) is usually limited to about 3nm normal and several PM parallel to the interface. High resolution microanalysis of cross-sectional samples by EELS and EDXS in a field emission STEM instrument is limited by the probe diameter and spreading, and the de-localization of inelastic scattering to about 2nm (theoretically), both normal and parallel to the interface. However, to obtain such a resolution, doses of the order of 108 to 1010 electrons/ nm2 are required. In semiconductors and particularly in oxides such doses lead to significant radiation damage and mass loss, often to the point of perforation of the sample.
Time-Resolved Electron Energy Loss Spectroscopy on Copper Oxides
Authors: Long N.J. , Skiff W.M. , Higgs A. , Carpenter R.W. , Lyman C.E.
Published: June 2020

In a previous paper it was shown that it is possible to distinguish CuO from Cu metal in a CuO/ZnO catalyst. It was also observed that the CuO showed signs of reduction under the impact of the high current density used in a field emission UHV STEM. This work reports on the efforts so far to study the changes in the L3, 2 edge of Cu as a function of time and hence ultimately to determine the kinetics of whatever radiation damage process is responsible for the changes observed in the catalyst CuO.

The first problem to be overcome was to provide a multichannel analyzer system capable of recording the same region of an ELS spectrum repeatedly and yet retain the individual scans. A Kevex 7000 series computer/MCA system was modified and software written which enables the user to select a region of a normal spectrum for subsequent analysis. An additional D to A converter, plus modified Gatan ELS spectrometer electronics, provided the means to offset the spectrometer magnet by an amount equal to the chosen windows so that the same energy window would be scanned sequentially. The electron microscopy was performed using a Philips EM400ST with a field emission gun at 100kV.
Energy-Filtered CTEM Image of MgO Smoke Particles
Authors: Kondo Y. , Yoshioka T. , Oikawa T. , Kokubo Y. , Kersker M.
Published: June 2020

The energy filtered imaging technique has so far been carried out in a scanning transmission electron microscope (STEM) fitted with a sector type energy analyzer. The STEM has a disadvantage of low beam parallelity because it uses a convergent beam, while the conventional transmission electron microscope (CTEM) allows good phase contrast and diffraction contrast to be obtained because of the high parallelity of the beam, and allows also high resolution images to be obtained. The technique to obtain energy filtered CTEM images has thus far been carried out by a Castaing-Henry type filter or an Ω type filter. However, these filters have the disadvantage of lower energy resolution than conventional sector type energy analyzer at the present time. This paper reports energy filtered CTEM images of MgO smoke, obtained using a new scanning CTEM image technique and a high energy resolution sector type energy analyzer which can resolve bulk and surface plasmon energy.
Structural Preservation of Thick Frozen Sections by Critical Point Drying
Authors: Tinglu Guan , Ris Hans
Published: June 2020

Stereoscopic Imaging of critical point dried (CPD) whole mounts of intact cells or isolated cell organelles using a high voltage electron microscope has provided new information on cellular organization. In such preparations the visibility of delicate structures is greatly improved since no embedding plastic is present. After permeabilization of the plasma membrane such whole mounts have also advantages over thin sections for immunolabeling of extended structures such as cytoplasmic filaments. In order to extend these advantages to tissue cells, plastics have been developed which can be extracted from the sections which are then dried by CPD. Another approach for obtaining embeddment free sections is cryosectioning. Modern rapid freezing techniques and cryoultramicrotomes can produce excellent sections free of ice crystal damage. However structural preservation so far has been unsatisfactory unless the sections were embedded in a layer of plastic.
An Analysis Of Residual Asbestos Remaining In Preparative Vials Following Bleach Digestion
Authors: Corn C. J. , Williams M. G. , Dodson R. F.
Published: June 2020

A continual question that concerns researchers using digestion techniques for the study of asbestos load in tissue is, “What percentage of the total fibers remains adhered to the walls of the preparative vials after digestion?“

In order to get a perspective on this problem, a test series was established which enabled us to define this residual fiber content following several variations in the rinsing procedure. The test material for all studies was a digested piece of lung tissue from a former asbestos worker. The digestion procedure used was based on the bleach digestion technique presented by Smith and Naylor. This tissue contained 3x108 fibers and 8x105 ferruginous bodies per gram and had a fiber per ferruginous body ratio of 37.5. Aliquots (1.5 ml) of the digest were used to create reproducible standards.
Technical Evaluation of Four Common Embedding Resins Used in Electron Microscopy
Authors: Juengel L.I. , Uphoff C. , Cole T.B.
Published: June 2020

Today, numerous types of embedding media are available for use in the electron microscopy laboratory. Laboratories generally choose a particular embedding media based on their own practical experiences with it. This study was performed to compare and evaluate four common resins found in electron microscopy laboratories.

Skeletal muscle was removed from rats perfused with 3% glutaraldehyde in 0.1M collidine, cut into rectangles and allowed to remain in fixative for 6 hours. Tissue was then washed in 0.1M collidine buffer and post fixed for 1 hour with 1% osmium tetroxide in 0.1M collidine. After rinsing in collidine buffer the tissue was divided into groups for processing according to established procedures for the following resins: Araldite, Epon, Mollenhauer, Spurr (see formulas).