bluuebunny/crossref_metadata_2025 huggingface dataset:
A Cytochemical Study of Glucose-6-Phosphatase (G-6-PASE) in Cells Participating in Atherogenesis of Rabbit Aorta
Authors: Kobernick Sidney D. , Elfont Edna A. , Brooks Neddra L.
Published: June 2020

This cytochemical study was designed to investigate early metabolic changes in the aortic wall that might lead to or accompany development of atherosclerotic plaques in rabbits. The hypothesis that the primary cellular alteration leading to plaque formation might be due to changes in either carbohydrate or lipid metabolism led to histochemical studies that showed elevation of G-6-Pase in atherosclerotic plaques of rabbit aorta. This observation initiated the present investigation to determine how early in plaque formation and in which cells this change could be observed.

Male New Zealand white rabbits of approximately 2000 kg consumed normal diets or diets containing 0.25 or 1.0 gm of cholesterol per day for 10, 50 and 90 days. Aortas were injected jin situ with glutaraldehyde fixative and dissected out. The plaques were identified, isolated, minced and fixed for not more than 10 minutes. Incubation and postfixation proceeded as described by Leskes and co-workers.
Ultrastructure and Fluorescence Histochemistry of Secondary Cells in the Eye of Aplysia Calijornica
Authors: Luborsky-Moore J. L.
Published: June 2020

The retina of the gastropod mollusc, Aplysia californica, contains receptor and nonreceptor (secondary) cells. The ultrastructure of the receptor cells, but not of the secondary cells, has been described. This report describes a study of the secondary cells (SC) using electron microscopy and the fluorescence histochemica1 method of Falck and Owman.

The secondary cells (15-18μm. in diameter) (Fig. 1) are situated along the periphery of the retina. The cells are ovoid and often have an irregular outline. They contain a slightly eccentric nucleus that is 8-10μm. in diameter. The SC cytoplasm lacks the numerous clear vesicles found throughout the receptor cell cytoplasm. The SC cytoplasm contains mitochondria, ribosomes, polyribosomes, neurotubu1es, neurofilaments, vacuoles, dense bodies, Golgi bodies, and dense core vesicles (inset, Fig. 1). The SC resemble neuroendocrine cells because they often contain large vacuoles and dense core vesicles. The vesicles (90-130nm. in diameter) contain a dense core (80-100nm. in diameter) surrounded by a clear halo.
Stereological Analysis of Endoplasmic Reticulum and Golgi Apparatus of Intestinal Enterocytes during Lipid Absorption
Authors: Manke Dean J. , Buschmann Robert J.
Published: June 2020

In fasting enterocytes there appears to be an abundance of rough endoplasmic reticulum (ER) and lesser amounts of smooth ER. During lipid absorption an apparent change to more smooth and less rough ER occurs (e.g. By measuring the volume and surface area of these membranous structures and the Golgi apparatus (GA) during lipid absorption we planned to determine if a simple conversion of rough to smooth ER accounts for the apparent change

In situ ligated segments of rat jejunum were injected with either a micellar solution of oleic acid, monoolein, and sodium taurocholate in buffered saline, or a non-lipid control solution of only buffered saline. At 0, 5, 15, 30 and 60 min segments were processed for electron microscopy. Villi were randomly thin sectioned (50-60 nm) and random electron micrographs obtained for analysis with standard stereological methods.
A Fine Structural Study of Mineralization Foci in Antler and Growth Plate Cartilage
Authors: Newbrey J. W. , Banks W. J.
Published: June 2020

Established staining techniques for glycosaminoglycans (GAG) and established demineralization techniques were employed to investigate the possible relationship of GAG's to hydroxyapatite crystals in mineralized cartilage. Cervine antler cartilage and rat growth plate cartilage were subjected to glutaraldehyde (6.25%) fixation, demineralized with ethylene diaminotetra acetic acid (EDTA) or acidic cacodylate buffer (pH 5.5), stained and postfixed with a ruthenium red (RR)-osmium tetroxide solution and prepared for routine transmission electron microscopy. Some tissues were subjected to hyaluronidase digestion prior to RR staining. Sections were stained with RR only or RR and uranyl acetate. The sections were examined with a Hitachi HS-8 electron microscope.

Matrix granules were positive to RR staining (Fig. 2&3). The granular density of the interterritorial zone was higher than that of the lacunar area; however, the lacunar granules were larger. After EDTA treatment, mineralization foci in the interterritorial zone were devoid of hydroxyapatite crystals.
Electron Microscopic Study of Tissues from Precolumbian Americans
Authors: Julio Martinez A. , Fultz Doris , Allison Marvin J. , Gerszten Enrique , Stanley Debra C.
Published: June 2020

Ultrastructural studies from tissues of Peruvian mummies ranging from 500 to 2000 years old have been carried out.

Even though the tissues had undergone extensive autolytic alterations many subcellular structures were still present and it was possible to clearly identify them. The better preserved tissues were those which contained abundant collagen and connective structures (Fig. 1-3). The collagen fibrils in particular showed the characteristic cross striations. The thickness of the dark bands was 45-50 nm while the thickness of the light bands measured between 25-30 nm.
Electron Energy Loss in Membrane Components: Possibilities of Contrast and Identification in the STEM
Authors: Hainfeld J. , Isaacson M.
Published: June 2020

It is well known that the energy loss spectra of fast electrons transmitted through thin specimens may he employed to analyze the material through which they have passed. Therefore, in principle, electrons can be used in a similar manner as one uses UV light to probe the chemical compositions of a specimen. The distinct advantage, of course, is the potential capability of utilizing the electron microscope for identifying compounds with microscopic spatial resolution (see, for example, Ref. 1). In biological membranes, for example, there thus exists the possibility of distinguishing proteins, phospholipids, cholesterol and carbohydrates on the basis of their electron energy loss spectra. This could be of value in delineating the twodimensional molecular architecture of membranes. We have therefore undertaken a program to determine the extent to which energy loss electrons can be useful in the scanning transmission electron microscopy of membranes.
Dynamic Surface Features of Cultured Cells Visualized by Combining Cinephotomicrography and SEM
Authors: Wetzel Bruce , Jones Gary , Westbrook Edwina , Fox Cecil , Sanford Katherine
Published: June 2020

The surface morphology of cells grown to subconfluent monolayers can be remarkably diverse and changeable. To study the dynamics of these surface features, cell growth and behavior can be observed by time-lapse cinematography without noticeably perturbing the culture,and the same cells reexamined by SEM1.

Mouse fibroblasts of nonneoplastic and neoplastic lines derived from a common single cell were trypsinized, then grown in NCTC-135 with 10% filtered fetal bovine serum in a 10% CO2 atmosphere for 48 hours at 37°C on glass coverslips within sealed glass flasks. During this period a field of cells was filmed at one frame/minute with phase contrast optics (80X). Cells were fixed by the addition of an equal volume of 6% phosphate-buffered glutaraldehyde for 90 minutes at 37°C, washed with distilled water, dehydrated through ethanol to amyl acetate, dried by the CO2 critical point method, and vacuum coated with carbon and gold-palladium.
SEM Evaluation of Canine Middle Cerebral Artery Endothelium Following Microvascular Surgery
Authors: Dujovny Manuel , Osgood Carroll P. , Barrionuevo Pedro J. , Longa EnriqueZea , Matta Richard
Published: June 2020

SEM of normal arterial endothelium has shown a constant picture of fine longitudinal ridges or folds. These folds are about 15 microns across, and their smooth undulations comprise a “normal” pattern which permits assessment of various types of early endothelial damage.

SEM affords rapid, stereoscopic study of relatively large areas of endothelium with ultrafine detail. Some microvascular maneuvers may mechanically distort or obliterate normal endothelial ridging. In addition, fibrin-platelet-red blood cell deposits may cover damaged endothelium.

Eighty canine middle cerebral arteries, 1.0 - 1.5 mm in diameter, were studied with SEM following: a) microtourniquet and microclip occlusion, b) pinching with jeweler's forceps, c) arteriotomy and suture, d) bipolar coagulation of a side branch 1 mm from the parent artery, 20 mv for 20 seconds, and e) end-to-side microanastomosis.

The initial event in arterial thrombosis is platelet adherence, and then platelet aggregation. These platelet clumps will begin to disperse or “wash out” 20 minutes post aggregation, so that 60 minutes later, platelet dispersion is fairly complete, if total arterial thrombosis and fibrin deposition have not occurred.
Ultrastructure Of Stressed Bovine Muscle
Authors: Carroll R. J. , Rorer F. P. , Jones S. B. , Cavanaugh J. R.
Published: June 2020

Measurements of a variety of physical properties of muscle tissue have been proposed as objective tests for meat tenderness. We have attempted to single out a specific physical factor, namely tensile stress, and to determine its effect on the ultrastructure of raw and cooked muscle tissue. Extension of this approach to the other physical factors involved in mastication will hopefully establish the structural factors important to meat tenderness.

The bovine semitendenosus muscle (eye round) was obtained either commercially or excised from a carcass aged under controlled conditions for 10 days. Small strips (¼” x ¼” x 1-½”), raw and cooked at 90°C, were subjected to tensile stress and then fixed in glutaraldehyde. A motorized minitensile stage (Fig. 1), designed to be small enough to operate within the SEM, stressed the muscle samples while viewed by a stereomicroscope and simultaneously monitored with a closed circuit TV system. Identical areas of samples subjected to tensile stress could be observed in both the light and scanning electron microscopes (Fig. 2).
Comparative Ultrastructure of Green and Xantha Redwood (Sequoia Sempervirens) Chloroplasts
Authors: Davis Ronald W. , Lasser Gerald W. , Bower Charles D.
Published: June 2020

A number of reports have appeared in the literature concerning chlorophyll and accessory pigment deficiencies in plants. These conditions are nearly always fatal as they result in nonfunctional chloroplasts. For this reason it was of considerable interest to find a wild redwood tree (Sequoia sempervirens) living in southern Humboldt County, about 15 feet tall and seemingly completely devoid of pigments.

Specimens of normal (green) and mutant (xantha) S. sempervirens leaves were taken for ultrastructural, lipid, and pigment analyses. Specimens were prepared for electron microscopy by placing small pieces of leaves in 5% glutaraldehyde in 0.2M phosphate buffer at pH 7.3 for 24 hours. Postfixation was in 2% OsO4 in phosphate buffer for 6 hours. Dehydration was by a standard acetone series and specimens were embedded in Spurr's LVEM. Ultrathin sections were cut with glass knives on a Reichert Ultramicrotome and examined with a Hitachi HU 11E electron microscope.

Chloroplasts of both the green and the mutant leaves were found in the thin layer of peripheral cytoplasm of leaf parenchyma cells.
The Effects of Induced Cryptorchidism upon the Principle Cells in the Rat Cauda Epididymis
Authors: Niewenhuis Robert J.
Published: June 2020

Cryptorchidism is known to cause inhibition of spermatogenesis and to decrease production of testosterone by the interstitial cells of the testes. The effects of this condition upon the epididymis is less clear. In addition, relatively little is known about the role played by the epididymal epithelial cells in the process of absorbtion, secretion and sperm maturation.

In this study the cauda epididymides of cryptorchid and vasectomized testes were studied with the electron microscope in order to see how these conditions affect the morphology of the epithelial cells of the epididymis.

Young adult male rats were divided into three groups. Animals in group 1 were rendered bilaterally cryptorchid and 25 days later a vasectomy was performed on one side only. Group 2 animals were bilaterally vasectomized and group 3 served as sham operated controls. All test animals were maintained for 90 days after vasectomy and then sacrificed.
Scanning Electron Microscopy and Microdissection of Single Drosophila Cells
Authors: Rizki T.M. , Allard L.F. , Rizki R.M. , Bigelow W.C.
Published: June 2020

The topographic features of biological structures including single cells have been revealed by scanning electron microscopy. It is likewise desirable to characterize the surfaces of intracellular organelles, and there are two general approaches to such investigations. The subcellular components can he fractionated and isolated prior to fixation and examination with the scanning electron microscope, or the cell can be dissected after it has been fixed as an intact whole. The latter method avoids artifacts associated with biochemical and mechanical manipulations for separation of individual components, and with adequate techniques of fixation should provide good resolution of surface texture of the larger intracellular organelles. For the present report the tissues and blood cells of Drosophila melanogaster larvae were fixed in situ with buffered formalin-osmic acid, dehydrated in alcohols and amyl acetate followed by critical point drying. Fractured, large pieces of the larvae were mounted on stubs and coated with about 150 Å of gold in a glow discharge coater.
Vibration Isolation for Ultramicroscopy
Authors: Ackerman L. D. , Cocks K. A. , Caughey R. C.
Published: June 2020

Ultramicrotomy remains a rather indefinite but necessary art for electron microscopists. One of the many factors which affects ultramicrotomy is extraneous vibration. Due to the construction of our facilities, difficulties were encountered. Upon the addition of more lab space it was desired to eliminate this problem. In conjunction with this goal several experiments were carried out in an attempt to assess the results quantitatively.

Two standard laboratory cabinets were used to make a tabletop by bridging them with a 24" x 60" x 2" slab of soapstone. A smaller slab, 12" x 24" x 2", was centered on this tabletop with vibration damping rubber between the two. An ultramicrotome (Sorvall MT-2B) was placed on this smaller slab. The new laboratory is one story above ground, so four deep, independent footings were poured to support four beams each which in turn supports a concrete platform in the sectioning area.
Tissue Processing of Mammalian Vascular Endothelium for Scanning or Scanning-Transmission Electron Microscopy
Authors: Robertson Abel L. , McKalen Anne
Published: June 2020

Samples of mammalian vascular endothelium,processed for surface scanning electron microscopy in the secondary electron emission mode or for transmission-scanning electron microscopy, were found to be susceptible to considerable artifacts during specimen preparation resulting in severe distortions in shape, size and spatial relationships.

Of all methods tested, freeze-drying or freeze substitution induced most severe artifactual problems due to differential shrinkage rates of underlying elastic layers. While critical point drying with carbon dioxide or Freon 13 proved to be consistently superior to the above methods, significant cellular lipid losses during processing were unavoidable. Use of nitrous oxide as suggested by Koller and Bernhard reduced delipidation but was found to give inconsistent results.

As an alternative, the following processing technique was developed and found to reduce morphological artifacts to a minimum while still preserving surface lipids and intercellular relationships.
Structure-Function Relationships in Mycobacteriophage R1
Authors: Soloff B. L. , Rado T. A.
Published: June 2020

Mycobacteriophage Rl, a lipid-containing virus lytic for Mycobacterium smegmatis, was propagated and purified according to methods described previously. The lipid component of this bacteriophage is essential for its survival, but the studies of Fay and Bowman indicated that treatment of the virus with organic solvents resulted in no release of DNA and suggested that no morphological alteration of the nucleocapsid occurred. More detailed analysis of the lipid moiety reveals two components which are present in the virus but absent in extracts of uninfected host. One of these appears related to esterified cholesterol and the other acts like a free fatty acid in chromatographic studies.

Treatment of phage on the grid with chloroform-saturated phage buffer caused little change in the appearance of the virus particles. By the same technic, treatment with a chloroform:methanol (2:1) solvent mixture resulted in disruption of the nucleocapsid and loss of DNA.
Alignment of Stereo Electron Micrographs for Projection
Authors: Mohr D. , Wray G.
Published: June 2020

Stereoscopic presentation of electron micrographs by means of a polarized light projector and polarizing glasses requires carefully aligned slides. Each stereo pair should be aligned so that little if any projector adjustment is required when going from slide to slide. Proper and consistent alignment allows the audience to grasp the stereoscopic information more readily.

Figure one shows a photograph of an alignment device for stereos. The two pictures can be moved in four ways: each film can be rotated, and one film translated both horizontally and vertically. The films are held in place by means of a vacuum. This leaves the front open so that the films can be easily transferred to a stereo mask by means of double-sided sticky tape once they are aligned.
In practice, a blank slide is first projected and the projector aligned so that the two images of the mask superimpose. The projector controls for horizontal and vertical movement remain fixed and the two films are then projected and moved until they are aligned.
Reflection Electron Diffraction of Catalase
Authors: Chatterjee T. K. , Spadaro J. A. , Vook R. W.
Published: June 2020

Matricardi et al. have shown that high energy electron diffraction patterns of unstained and unfixed catalase may be obtained with a high voltage TEM using a hydration stage and that without such a stage TED patterns could not be obtained. They showed that such patterns were observed only when the water vapor pressure in the vicinity of the catalase was greater than 90 percent of the equilibrium value. They attributed their results to the destruction of the crystallinity of catalase when it is vacuum dried. Similar results using X-ray diffraction techniques have been reported. Matricardi et al. also noted effects due to radiation damage, whereby the number of reflections observed using the hydration stage decreased substantially with electron beam exposure. In the present preliminary report, it is shown that electron diffraction patterns can be obtained from unstained and unfixed catalase even when the crystals are exposed directly to the vacuum of the TEM but under such conditions whereby the electron beam intensity is reduced by up to approximately two orders of magnitude from that usually obtained in normal TED work on a TEM.
Copper Storage Bodies in the Hepatopancreas of the Isopod, Oniscus Asellus
Authors: Roberts John W. , Witkus E.R.
Published: June 2020

The hepatopancreas of the Isopod, Oniscus asellus consists of two pairs of blind-ending diverticula. Two types of mature cells are found: secretory cells (B-cells) and storage cells (S-cells). Both differentiate from a common stock of regenerative cells located at the blind end of each lobe.

The appearance of what Weiser (1968) calls copper-storage bodies in the S-cells first occurs in the area of each lobe where the transitional cells differentiate into either mature secretory (B) cells or storage (S) cells. Figure 1 shows a basophilic S-cell sandwiched between two acidophilic B-cells. Figure 2 shows an electron micrograph of S-cell storage bodies with different affinities for electron-dense stain.

By employing the method of Scheuer-et al (1967) copper localization was demonstrated only in S-cells. No copper was adsorbed into the B-cells but was actively absorbed into adjacent S-cells. This might indicate a mechanism for selective copper absorption in S-cells and no such mechanism in B-cells.
Scanning, Transmission and Electron Probe Analysis of the Cat Tapetum
Authors: Turnbill C. E.
Published: June 2020

The tapetum lucidum or “bright carpet” of the cat eye is an adaptation for vision in limited light. The tapetum is of particular interest to our laboratory in that it might be used as a visual maker for cosmic “heavy primary” radiation. Since this marker would be located rear the retina, it would provide close correlation between high energy particle trajectories and related retinal damage. In preparation for this task, the cellular tapetune of adult cats were examined as controls.

Adult cats were perfused with 2% glutaralderhyde, 2% paraformaldehyde and placed in cacodylate buffer. The tapetune was separated from the retina and choroid and processed for either scanning or transmission microscopy.

Material for the transmission microscope was postfixed in 1% osmium tetroxide and examined both stained, with uranyl acetate and lead, and unstained for microprobe analysis. The stained sections (Fig. 1) cut parallel to the axis of the retinal rods, show layers of cells filled with electron dense rod-like structures approximately 10 microns by .1 micron.
Analytical Electron Microscopy in Secretory Cell Studies
Authors: Johnson D.E. , Izutsu K.T.
Published: June 2020

There is currently much interest in detailing the secretion-related changes in intracellular elemental concentrations of exocrine glands because of their fundamental roles in secretion processes. Numerous in vivo, in situ and in vitro studies utilizing radioisotopes flame photometry and ion-specific electrodes have shown the importance of Ca. Na. K. Cl and HC03 ions to secretion. The Analytical Electron Microscope is uniquely capable of yielding specific and quantitative information about subcellular elemental concentrations that complements information from the preceding types of studies. The research to be described concerns the application of this method to the study of secretion- related. elemental concentration changes in the rat parotid gland. We have found significant secretion-related changes in levels of Na, K. Cl and/or osmolarity in secretory granules, cytoplasm and nuclei of parotid acinar cells. These changes have important physiological implications. In other studies underway, we have measured significant subcellular elemental concentration differences between human labial salivary gland tissue from normal controls and cystic fibrosis (CF) patients.
TEM/STEM Characterization of Rapidly Solidified Aluminum Alloys
Authors: Kar R. J. , McHale T. P. , Kessler R. T.
Published: June 2020

Low-density and high strength-type rapidly solidified (RST) aluminum alloys offer promise for structural aerospace applications. At Northrop, as part of a continuing program to establish structure-property relationships in advanced materials, detailed transmission electron microscopy (TEM)/scanning transmission electron microscopy (STEM) of candidate RST aluminum-lithium (Al-Li) and high strength (7XXX-type) aluminum-copper-magnesium-zinc (Al-Cu-Mg-Zn) alloys is routinely performed. This paper describes typical microstructural features that we have observed in these alloys.

Figure 1 illustrates the microstructure of an inert-gas atomized RST Al-Li-Cu-Mg-Zr alloy. Frequently the grain boundaries are decorated with continuous or semi-continuous stringers of oxide that are relatively opaque to the incident electron beam. These have been identified to be Al-,Mg-, and Li- containing oxides present on powder particle surfaces prior to consolidation, and which have not been adequately broken up and dispersed by post-consolidation processing. The microstructures of these alloys are generally characterized by unrecystallized grains and equiaxed sub-grains pinned by fine (0.2μm) precipitates. These have been identified to be Al3Zr dispersoids using a combination of selected area diffraction/energy-dispersive x-ray (SAD/EDX) methods.
Alternative Crystallization Phases in Sub-Micron Droplets of Fe-Ni Alloys
Authors: Kim Yeon-Wook , Kelly Thomas F.
Published: June 2020

When a liquid becomes highly supercooled, the crystal phases that nucleate from it may be one of several alternatives other than the primary crystallization phase. Even though these crystal phases would be metastable at the liquidus temperature of the primary crystallization phase, they may or may not be the most stable crystal phase at the nucleation temperature. Thus the term “metastable phase” is not generally applicable and the name “alternative crystallization phase” (ACP) is used.

In order to determine whether a particular crystal phase may nucleate in a supercooled liquid, it is not sufficient to determine simply which phase has the greater liquidus temperature. The effect of liquid supercooling (relative to the liquidus temperature of each phase) on the nucleation of each possible phase must be considered. For a given situation (eg. liquid volume, cooling rate,…), the propensity of a given phase for nucleating from the supercooled liquid can be gauged by calculating a nucleation temperature for that phase [1].
HREM Profile Image Interpretation In MgO Cubes
Authors: O'Keefe M. A. , Spence J. C. H. , Hutchison J. L. , Waddington W. G.
Published: June 2020

For the most credible interpretation of HREM images, it is desirable to match computed and experimental images against the variation of some parameter, usually either specimen thickness or defocus (and preferably both). MgO smoke forms in perfect crystalline cubes, so that the thickness, T, of a cube in <110> zone axis orientation can accurately be determined by geometry at each co-ordinate X (normal to the wedge edge) in the image. Figure 1 shows such an experimental 90° MgO wedge lattice image recorded in an exact <110> orientation using a JEOL 200CX. Dynamical multislice calculations for the thickness dependence of the inner beams important for imaging are shown (c) scaled to the abscissa of the experimental image (the crystal thickness, T, at any point is twice the X value shown). Analysis of this image by means of simulated images (not shown) shows the thin-crystal “structure” image changing to one containing vertical (220) fringes at A (due to strong second-order (111) x (111) interference), to a re verse-contrast image at C, to one with horizontal (002) fringes at B (from strong (111) x (111) interference), and to a “structure“-like image at D. Matching with simulated images provides a rare possibility for guantitative structure analysis by HREM, since the complex low order structure factors can be adjusted in the dynamical calculation until the contrast reversals and other turning points occur at the observed thicknesses.
Comparison of Conventional and Electron Spectroscopic Imaging in the Fixed Beam Electron Microscope of Ordered Protein Arrays
Authors: Buhle E. L. , Aebi U.
Published: June 2020

CTEM brightfield images are formed by a combination of relatively high resolution elastically scattered electrons and unscattered and inelastically scattered electrons. In the case of electron spectroscopic images (ESI), the inelastically scattered electrons cause a loss of both contrast and spatial resolution in the image. In the case of ESI imaging on the Zeiss EM902, the transmited electrons are dispersed into their various energy components by passing them through a magnetic prism spectrometer; a slit is then placed in the image plane of the prism to select the electrons of a given energy loss for image formation. The purpose of this study was to compare CTEM with ESI images recorded on a Zeiss EM902 of ordered protein arrays. Digital image processing was employed to analyze the average unit cell morphologies of the two types of images.
Analytical Electron Microscopy of a Polymer Blend
Authors: Haddock T. , Krause S.J. , Kumar S. , Adams W.W.
Published: June 2020

A polymer blend which is composed of poly-p-phenylene benzobisthiazole (PBT) and poly-2,5(6)benzimidazole (ABPBI) has been processed into both a phase-separated material and a “molecular composite”. In the molecular composite, the PBT and ABPBI components are dispersed at a scale finer than 3 nm. This results in high mechanical properties as the rod-like, high strength PBT reinforces the flexible-coil ABPBI matrix. In the phase- separated blend, micron-sized aggregates form within a more ductile matrix. This study qualitatively examines the structure and composition of the phase- separated 20% PBT / 80% ABPBI blend using the analytical electron microscopy (AEM) techniques of energy dispersive x-ray spectroscopy (EDS), electron energy loss spectroscopy (EELS), and microdiffraction. Beam damage of the components is also considered.
Effects of the Elements Ni, V, Co on Ultrastructure of the Heart Muscle
Authors: Kovach A.G.B. , Balogh I. , Rubanyl G.
Published: June 2020

The finding of altered distribution of metallic elements in the infarcted myocardium and the demonstration of elevated serum Ni concentration in patients with myocardial infarction, burns, shock and toxemia have indicated that elements, like Ni, V, Co etc. may play important role in cardiovascular and obstetrical pathology, This report explains cardiovascular effects of nickel, vanadium, and cobalt ions at elevated concentration and gives valuable information about the possible physiological and pathological significance of these elements.

METHOD

Isolated rat hearts were perfused by Krebs-Ringer bicarbonate solution for 15 minutes at room temperature. Various doses of nickel chloride, sodium vanadate and cobalt chloride (1-100 uM) were then added to the Krebs solution.
Development of a New TEM With an Image Rotation System
Authors: Isakozawa S. , Kobayashi H. , Ohashi T. , Tomita M. , Kamimura S.
Published: June 2020

We have developed a new 125KV TEM (Fig. 1). It incorporates an electron gun operable up to 125KV, 3-stage illumination lens system, and 5-stage imaging lens system. Microprocessors are used to control the high voltage, electron optics and vacuum system.

In the high voltage system, accelerating voltage is variable from 10KV to 125KV with increments of 100V/step. In the low voltage operation at 10KV and 25KV,the anode to wehnelt distance is automatically controlled for optimum gun brightness. Filament and bias voltage supplies are also precisely regulated to give stable emission currents at all accelerating voltages.

Imaging lens system is free of image rotation during magnification change from 100x to 500,000x. In addition, a new image rotation system is built in. This image rotation system utilizes the individual lens data such as rotation angle, focal length, etc. When a required image rotation angle is given, the computer determines excitation condition of each lens for a selected magnification.
A Field-Effect Fim Specimen Holder For Jeol 200CX
Authors: Walck S. D.
Published: June 2020

Very large field-induced stresses are imposed on specimens in the Field-Ion Microscope (FIM) and the magnitude of these stresses approach the theoretical strengths for many metals. The interaction of the field- induced stresses with defects such as grain boundaries or precipitates is usually the cause of fracture failure of samples in the FIM. It has long been known that the stresses in the emitters cause most dislocations to be swept out of the sample in the field-affected region. Frequently, results obtained by FIM techniques are questioned because of the presence of these stresses. Eaton and Bayuzick used a FIM image-brightness, mapping technique to find the actual geometry of a tungsten specimen and then obtained the stress state within it by using finite element analysis. Their analysis shows the distribution of shear stresses to be quite complicated.
The Basic Physical Principles of Ion, Electron, and X-Ray Detectors and Their Application to Microanalysis
Authors: Tousimis A.J.
Published: June 2020

An integral and of prime importance of any microtopography and microanalysis instrument system is its electron, x-ray and ion detector(s). The resolution and sensitivity of the electron microscope (TEM, SEM, STEM) and microanalyzers (SIMS and electron probe x-ray microanalyzers) are closely related to those of the sensing and recording devices incorporated with them.

Table I lists characteristic sensitivities, minimum surface area and depth analyzed by various methods. Smaller ion, electron and x-ray beam diameters than those listed, are possible with currently available electromagnetic or electrostatic columns. Therefore, improvements in sensitivity and spatial/depth resolution of microanalysis will follow that of the detectors. In most of these methods, the sample surface is subjected to a stationary, line or raster scanning photon, electron or ion beam. The resultant radiation: photons (low energy) or high energy (x-rays), electrons and ions are detected and analyzed.
Practical Aspects of Preparing Thin Sections From Catalyst Specimens
Authors: Chan I. Y. , Cain J. H. , Rea T. M.
Published: June 2020

Transmission electron microscopy is an important technique for catalyst characterization. The thin-sectioning technique has been recognized as the preferable specimen preparation method in most cases. The merit of this technique has been discussed in a number of publications. It has been applied to catalysts containing alumina, carbon, silica, and zeolites. In this paper, we present the practical aspects we have found for obtaining high quality thin sections consistently.

Requirements

1.

The sections should be mechanically and electrically stable under the electron beam.

2.

They should be as thin as possible in order to achieve the highest image resolution permitted by the instrument.

3.

The results should be readily reproducible so that comparison between similar samples can be made easily.

4.

The number of artifacts (e.g., those arising from shatter marks, knife marks, and thickness variations) should be minimized.
Crystal Site Occupancy of Alloying Elements in Polycrystalline Nb3Sn Superconductors By Electron Channeling
Authors: Tafto J. , Sabatini R. L. , Suenaga M.
Published: June 2020

Many of the crystallographic problems encountered in materials science require techniques that can be used on small volumes of materials, e.g., in VLSI semiconductors, thin films, and the composite materials used in high magnetic field superconductors. In recent years several sensitive and accurate microcrystallographic techniques, based on diffraction of 100-keV electrons, have been developed. For example, convergent beam electron diffraction is a powerful technique to determine the symmetry of microcrystals and electron channeling techniques for the location of dilute elements in the crystal unit cell.

We shall here deal with the application of the electron channeling technique called ALCHEMI (Atom Location by Channeling Enhanced Microanalysis) to study composite materials by determining the crystal sites of small amounts of alloying elements in Nb3Sn made by the bronze process. This is a problem of considerable interest in conjunction with the development of high magnetic field superconductors, because small amounts of certain alloying elements increase the upper critical magnetic field significantly.
Microcracks and Micro-Twins in Partially Stabilized Zirconia Alloys (PSZ)
Authors: Lu Y.N. , Tighe N.J.
Published: June 2020

Three commercial magnesia-doped partially stabilized zirconia ceramics (Nilsen MS and TS and Coors TT), have been examined before and after aging for 100 hours at 1000°C The proposed use of these ceramics for components in diesel engines requires long term reliability at temperatures up to 1000°C. The microscopy is being used to identify the microstructural changes that can result during high temperature tests carried out in this laboratory.

Pure zirconia exists in three polymorphs which on cooling transform from cubic to tetragonal (at -2200°C) to monoclinic (at -950°C). With MgO additions and under appropriate conditions of temperature and time, the tetragonal to monoclinic transition can be controlled to produce partially stabilized magnesia zirconia alloys with grains and intergranular phases that are mixtures of monoclinic, tetragonal and cubic phases. The morphology of the grains and intergranular phases is readily distinguished in polished sections; however, the phase distributions can be confirmed only with electron microscopy. For example, the intergranular phase is predominantly monoclinic and grains can have: transgranular monoclinic plates in a cubic matrix; twinned monoclinic plates in a cubic matrix; distributions of tetragonal precipitates in a cubic matrix. The microcracks are found by examining interfacial regions at high magnifications.
Weak-Beam Imaging of Coherent Twin Boundaries After High-Temperature Deformation
Authors: Rajan Krishna
Published: June 2020

Weak beam dark field microscopy has been used extensively to study deformation induced intragranular defects in materials. However as noted by Tones et al weak beam imaging is also an asset in examining intergranular defects. The localisation of strain contrast close to the defect core by weak beam imaging allows the interaction of matrix dislocations with the boundary (to form extrinsic dislocations) to be studied more easily. Also, the reduction in extinction distance with weak beam microscopy produces a higher density of extinction contours, which allows topographical discontinuities associated with long range strain fields to be more readily observed.

Thus in the present study, where we were interested in interfacial phenomena during high temperature deformation processing of a cobalt base alloy (Co-Cr-Mo), weak beam imaging was used to obtain a better understanding of the role of intergranular defects.
AEM of Grain-Boundary Precipitation in Type 304 Stainless Steels Containing N
Authors: Betrabet Hemant S.
Published: June 2020

A systematic analytical electron microscope (AEM) study was conducted on a series of 18Cr-8Ni stainless steels in order to determine the effect of N additions on sensitization. This phenomenon is associated with intergranular carbide (Cr23C6) precipitation, and the subsequent Cr depletion of the surrounding region, and leads to susceptibility to intergranular corrosion and intergranular stress corrosion cracking. Sensitization can be retarded by reducing the C content of the steels, but this causes an unacceptable loss of mechanical properties. A better solution is to replace much of the C by N.

A series of steels with varying N (0.04-0.25 wt%) and C (0.02-0.07 wt%) contents were studied in the AEM, and the results compared with electrochemical potentiokinetic reactivation (EPR) test data used to measure the degree of sensitization (DOS). EPR tests indicate that N additions up to 0.16 wt% retard sensitization, but above 0.16 wt% promote it, a result which does not agree with thermodynamic calculations of carbide precipitation which show that N slows the Cr23C6 growth kinetics, even at levels above 0.16 wt%.
Three-Dimensional Algebraic Reconstruction From Three Mutually Orthogonal Projections
Authors: Jiye Ximen , Zhifeng Shao
Published: June 2020

The classic reconstruction problem is that of reconstructing a 3D object from its 2D projections /1-5/. It is also well known that the principal difficulty in solving this problem in electron microscopy is that a very large number of independent projections are normally required. Recently it has been shown /3,4/ that if we restrict our attention to binary or Boolean objects, far fewer projections are needed in order to obtain an approximate solution. 2-dimensional solutions of ID projections were demonstrated using only four views and 3-dimensional reconstruction of 2D projections were obtained by dividing the projections into identifiable slices.

In the present paper, an algebraic reconstruction technique (ART) has been studied which uses three mutually orthogonal projections.
Cryo-Electron Microscopy and Image Analysis of SV40
Authors: Baker T. S. , Drak J. , M. Bina
Published: June 2020

The discovery that the T=7 icosahedral capsid of polyoma virus is composed of 72 pentameric capsomers rather than 12 pentamers and 60 hexamers as predicted by constraints of quasi-equivalence has prompted an examination of SV40 virus by electron microscopy to determine whether the capsids of other members of the papovavirus family are similarly constructed.

Thin layers of buffered aqueous solutions (∼4 mg/ml) of Simian virus 40 (strain WT776) were prepared for cryo-microscopy using recently developed procedures. Images of virus particles suspended in thin layers of vitreous ice over holes in the carbon support film and maintained at -170°C were recorded using minimal irradiation conditions. Figure 1 shows a typical field in which the frozen solution is similar in thickness to the virus particles (∼49 nm diameter). Particles appear to be excluded or squeezed away from the thinnest regions of solution (e.g., the clear region bordered by particles at the top of Fig. 1).
Radial Mass Density Analysis of Unstained Stem Images
Authors: Furcinitti P.S. , Hainfeld J.F. , Lipka J.J. , Wall J.S.
Published: June 2020

The high contrast and signal-to-noise ratio inherent in the Scanning Transmission Electron Microscope (STEM) makes it possible to examine unstained, freeze-dried biological macromolecules. Since the large-angle, elastically scattered STEM signal is directly proportional to the specimen mass, molecular weight or mass per unit length determinations are possible for individual macromolecules. For objects which have cylindrical or spherical symmetry the resolution lost by sparse sampling (2 Å spot, 5 or 10 Å between pixels) may be regained by employing the “Vernier Sampling” method developed by Steven et al. to rebin the data on a finer grid. A projected mass distribution is then obtained for the average values of the mass per unit area on an axis perpendicular to the symmetry axis. Assuming the particle to consist of a set of concentric cylinders of varying density, a set of simultaneous equations can be solved for the mass density at each annular ring. Thus the outer diameter and the internal radial structure of complex macromolecules Can be determined.
Small-Spot Illumination For High-Resolution Electron Microscopy of Beam-Sensitive Specimens
Authors: Downing Kenneth H. , Glaeser Robert M.
Published: June 2020

The contrast observed in images of beam-sensitive, crystalline specimens is found to be significantly less than one would predict based on observations of electron diffraction patterns of the specimens. Factors such as finite coherence, inelastic scattering, and the limited MTF of the photographic emulsion account for some decrease in contrast. It appears, however, that most of the loss in signal is caused by motion of the specimen during exposure to the electron beam. The introduction of point and other defects in the crystal, resulting from radiation damage, causes bending and lateral motion, which degrade the contrast in the image. We have therefore sought to determine whether the beam-induced specimen motion can be reduced by reducing the area of the specimen which is illuminated at any one time.
Bonafide Substructure in the Core of Ferritin
Authors: Massover William H.
Published: June 2020

Each molecule of ferritin (d = 130Å) contains a core of iron surrounded by a 24-subunit protein shell. The amount of iron stored is variable and is present within the central cavity (d = 80Å) as a hydrated ferric oxide equivalent to the mineral, ferrihydrite. Many early ultrastructural studies of ferritin detected regular patterns of a multiparticulate substructure in the iron-rich core [e.g., 3,4], Each small particle was termed a “micelle“; a theory became widely accepted that a core consisted of up to six micelles positioned at the vertices of an octahedron. Other workers recognized that the apparent micelles were smaller or even disappeared if images were recorded closer to exact focus [e.g., 5]. In 1969, Haydon clearly established that the observed substructure was really an imaging artifact; each apparent micelle was only a dot in the underfocused phase contrast image of the supporting film superimposed on the amplitude image of the strongly scattering metal.
Identification Of G-Phase In Aged Cast CF 8 Type Stainless Steel
Authors: Bentley J. , Miller M. K. , Brenner S. S. , Spitznagel J. A.
Published: June 2020

The microstructure of as-cast and aged CF 8 type stainless steel, used for the primary coolant pipes in pressurized light-water nuclear reactors, is being studied by analytical electron microscopy (AEM) and atom probe field-ion microscopy (APFIM). The phase transformations of the ferrite (∼19 vol % of the duplex structure) that occur after aging at 673 K for 7500 h are described by Miller et al. The present work deals with the identification of G-phase (prototype compound Ni16Ti6Si7) observed in the ferrite of aged material.

In FIM images the precipitates had bright contrast, appeared roughly spherical, were ∼10 nm in diameter, and were present at a concentration of ∼1023 m-3. Atom probe selected area microchemical analyses of the central portion of five precipitates revealed that they were alloy silicides, Table 1.
TEM Investigation Of Hydrogen-Induced Phase Transitions In Stainless Steel
Authors: Minkovitz E. , Eliezer D.
Published: June 2020

The role of martensitic phase transitions in the embrittlement of stainless steels by hydrogen has been one of persistent controversial theme studied during recent years. The unresolved question, concerns the role of hydrogen in hydrogen induced phase transformation of the γ(fcc) austenite to α‘(bcc) and ɛ (hcp) martensite phases in the fracture mechanisms. The purpose of this study is to report the results of a TEM analysis of martensitic phase transitions under conditions of high hydrogen fugacities such as cathodic polarization in the absence of any externally applied stress.

The results demonstrate the appearance of hydrogen induced ɛ-phase in 316L steel (Fig. 1(b)). No evidence of the appearance of α'-martensite phase after hydrogen charging was found within the grains, however, α'-martensite was found in front of the crack tip and along the crack surfaces as a very fine-grained polycrystalline structure (Fig. 1(c)).
Enhancement of the Order/Disorder Reaction in Fe-Ni
Authors: Reuter Kathleen B.
Published: June 2020

The Fe-Ni phase diagram is not well understood below 400°C. Of particular interest in this region is a disorder to order reaction whereby Fe-50 wt% Ni transforms from an FCC structure to an L1o superstructure. The kinetics of this transformation, however, are extremely slow (Table I). Therefore, to observe low-temperature transformations in the Fe-Ni system, extremely slow-cooled alloys must be studied (e.g., meteorites) or diffusion must be enhanced. One method to speed diffusion is irradiation. In 1962 Fe-50 wt% Ni was neutron irradiated; electrical resistivity measurements revealed a critical temperature (Tc)of 320°C. In 1977 Fe-50 wt% Ni was irradiated on a high voltage electron microscope (HVEM) and a T of 320°C was again found. A question arises, however, whether radiation enhanced diffusion or whether the radiation induced the transformation, causing a non-equilibrium ordered phase to form.