bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonvolatile Octavalent Osmium Compounds as Sources of Osmium Tetroxide for Electron Microscopic Cytochemistry
Authors: Hanker J. S. , Romanovicz D. K. , Crenshaw M. A.
Published: June 2020

A number of compounds of osmiumVIII including osmiamates and coordination complexes of OsO4 with various heterocyclic nitrogen compounds have been synthesized, characterized and evaluated as substitutes for OSO4 in cytochemistry. The compounds synthesized include ammonium osmiamate (NH4OsO3N), potassium osmiamate (KOSO3N), and addition complexes of OSO4 with hexamethylenetetramine, pyridine, quinoline, piperazine, and sym. collidine.

The ammonium osmiamate was relatively unstable. The potassium osmiamate, although stable, was insoluble. Pyridine formed a stable yellow complex with OsO4 which was insoluble in water and sublimed readily at room temperature. All of the other nitrogen heterocycles formed unstable molecular addition complexes which decomposed in a short period of time with the exception of hexamethylenetetramine. The latter formed a stable complex, which had a negligible vapor pressure of OSO4, and did not sublime like many of the other octavalent osmium compounds. Spectroscopic studies, potentiometric titration,elemental analysis, and atomic absorption studies with an osmium lamp indicated the structure shown in Fig. 1 (top).
Mitochondrial Oxidation of p-N, N-Dimethylamino-β-Phenethylamine (DAPA)
Authors: Allen Shannon W. , Wasserkrug Hannah L. , Seligman andArnold M.
Published: June 2020

The synthesis of a new substrate, p-N,N-dimethylamino-β-phenethylamine (DAPA)3 (Fig. 1) (1,2), and the testing of it as a possible substrate for tissue amine oxidase activity have resulted in the ultracytochemical localization of enzyme oxidase activity referred to as DAPA oxidase (DAPAO). DAPA was designed with the goal of providing an amine that would yield on oxidation a stronger reducing aldehyde than does tryptamine in the histochemical demonstration of monoamine oxidase (MAO) with tetrazolium salts.

Ultracytochemical preparations of guinea pig heart, liver and kidney and rat heart and liver were studied. Guinea pig kidney, known to exhibit high levels of MAO, appeared the most reactive of the tissues studied. DAPAO reaction product appears primarily in mitochondrial outer compartments and cristae (Figs. 2-4). Reaction product is also localized in endoplasmic reticulum, cytoplasmic vacuoles and nuclear envelopes (Figs. 2 and 3) and in the sarcoplasmic reticulum of heart.
The Basal Apparatus of Bovine Retinal Rods
Authors: Raveed Dan , Fleischman Darrell
Published: June 2020

Several types of mammalian sensory receptor cells possess modified cilia which may play a primary role in stimulus detection. Axonemes and basal apparatus from other types of cilia and flagella have been isolated, characterized and compared in detail. In this communication we report results of what may be the first attempt to isolate and characterize such structures from a sensory cilium, the bovine retinal rod outer segment.

Bovine eyes were obtained from a nearby abattoir, the retinas were removed and swirled vigorously in a cold solution of 50% sucrose, 5 mM Tris, 2 mM MgCl2, pH 7.5, to detach outer segments. The suspension was then filtered through cheesecloth and the filtrate was centrifuged at 20,000 rpm for 1 hr. Rod outer segments were collected from the solution surface, diluted, layered onto a continuous sucrose gradient (25-38% sucrose in Tris MgCl2 buffer) and centrifuged for 3-12 hrs. at 10,000 rpm.
Morphological Observations on Anterior Endoderm in Cardiac Mutant Mexican Salamanders (Ambystoma Mexicanum)
Authors: Lemanski Larry F. , Marx Barry S.
Published: June 2020

Humphrey reported the discovery of a recessive mutant gene, designated c for "cardiac lethal" in a dark stock of axolotls, Ambystoma mexicanum, imported from Mexico by Dr. Louis DeLanney. Homozygous recessive embryos exhibit a total absence of heart contractions even though initial heart development appears normal. Ultrastructural studies indicate that the mutant hearts fail to contract because the myocardial cells lack organized myofibrils. In further studies, Humphrey performed transplants of mutant (c/c) heart primordia into the heart regions of normal (+/+) recipients and found the cardiac defect to be corrected. When reciprocal transplants were made, no heart beat was observed. It was further shown that parabiosis of normal embryos with mutant siblings did not correct the cardiac deficiency nor were the normal parabiotic twins adversely affected by this procedure; such conjoined animals lived for up to several months and the mutant twins, except for lacking a functional heart, appeared normal.
Direct Visualization of the Hydrophobic Portion of Acholeoplasma Laidlawii Membranes
Authors: Heckman C. A. , Barrnett R.J.
Published: June 2020

Alteration and extraction of lipids occur during the preparation of biological tissues for electron microscopy. This problem has rendered the interpretation of membrane fine structure in molecular terms particularly difficult. By using a water-miscible, glutaraldehyde-carbohydrazide (GACH) resin polymerized at neutral pH, we have previously demonstrated lipid retention in biological tissues during embedding. Since A. laidlawii membranes have been characterized with regard to the composition and structural organization of the lipid component, they provided an ideal model system for direct visualization of the retained lipids after GACH embedding.

High resolution micrographs of the membranes were taken on a Hitachi HU-11B electron microscope. At the same time, the instrument was calibrated according to established guidelines and found to give a standard deviation of 2.9% in magnification over a period of approximately one year. A. laidlawii strain B cells were generously provided by Dr. James Gilliam. The presence of an intact, hydrophobic core in sections of GACH-embedded membranes was confirmed by vanatomolybdate staining of the thin sections.
The Identification of Phospholipid Micelles in Glutaraldehyde-Urea Embedded Tissue
Authors: Pease Daniel C.
Published: June 2020

It is reasonable to think that phospholipid micelles should be visible and identifiable in electron micrographs of ultrathin sections if only they can be preserved throughout the embedding process. The development of highly polar, water-containing, aminoplastic embedments has made this a likely possibility. With this in mind, an investigation of the lecithin-secreting, Type II pneumocytes of the lung is underway.

Initially it has been easiest to recognize phospholipid micelles in lung tissue fixed first with glutaraldehyde, and then secondarily exposed to osmium tetroxide. However, the latter is not a necessary concomitant for micellar preservation. Conventional uranyl acetate and lead citrate staining is finally applied. Importantly, though, the micelles have been most easily seen in tissue embedded in 507. glutaraldehyde polymerized with urea, as described in detail by D.C. Pease and R.G. Peterson (J. Ultra- struct. Res., 41, 133, 1972).
When oriented appropriately, the micellar units are seen as tiny, bilayer plates.
Fusion of Sarcoplasmic Reticulum with Ruthenium Red
Authors: Wallace N. , Sommer J.R.
Published: June 2020

Howell recently reported the effect of Ruthenium Red (RR) on the sarcoplasmic reticulum (SR) of frog skeletal muscle after long exposures to that dye. Howell observed staining of the junctional granules within the junctional SR (terminal cisternae), and fusion of the so-called intermediate cisternae that are intercalated between junctional and free SR. This is an important observation because it may provide, first, needed additional evidence for a structural definition of the so-called intermediate cisterna, and second, the fusion of the intermediate cisternae under these circumstances suggests that they might have properties that are different from, or in addition to those of the junctional and free SR, respectively. For example, membrane fusion in that region might conceivably occur in vivo under certain circumstances in which case a large proportion of the SR might become separated, electrically, from the junctional SR. As a result, at least temporary openings of the junctional SR to the extracellular space remain a possibility even during depolarization.
Scanning Electron Microscopy of Elliptocytes in Man and Llama
Authors: Pardo Matias , Grauer Robert C. , Swart James H. , Hartsock Robert J.
Published: June 2020

Elliptical red cells may be found in man, camels, llamas, birds and reptiles. In man, these cells can occur as an autosomal dominant disease. Using a shadow-casting technic, Rebuck and Van Slyck found a constant bipolar massing of hemoglobin in the elliptical cells of man. This polar massing of hemoglobin was not observed in the red cells of the llama. From these observations they deduced that the elliptical cells in man were biconcave whereas the cells from the llama were uniformly elliptical without a zone of central thinning.

The scanning electron microscope was used to confirm these observations by comparing the red cells from a patient with hereditary elliptocytosis with red cells from a llama. As shown in Fig. 1, the elliptical cells of man are canoe-shaped. Bipolar massing of hemoglobin in these cells is seen in the red cell in Fig. 3. These observations are contrasted with red cells from the llama which are also elliptical, but they lack a central zone of thinning as shown in Fig. 2.
Relationship of the Discocyte—Echinocyte Shape Transformation to Red Cell Surface Charge
Authors: Marikovskyand Y. , Brown C.S. , Wortis H.H.
Published: June 2020

ATP-depletion of red blood cells (RBCs) by glucose deprivation transforms RBCs from the normal discocyte configuration into echinocytes. In the course of this shape change, there is a significant loss of membrane sialic acid, a decrease in cell surface negativity, and survival studies show that RBCs have an abbreviated life span. It is not known if the loss of negativity and decreased survival are directly related to nucleotide depletion or if they may be an inevitable consequence of the discocyte-echinocyte shape transformation.

In the current study, we examined the effects of rapid discocyte-echinocyte transformations on RBC surface charge, as measured by cationized ferritin binding and agglutination rates in the presence of poly-L-lysine. Lysolecithin (LYL) is a strongly echinocytogenic lipid that transforms human RBCs into echinocytes in > 5 minutes, in contrast to ATP depletion by the method of Weed et al, which requires many hours to accomplish the same transformation.
Expression of HeLa Cell Surface Alkaline Phosphatase During Attachment to Gla
Authors: Max Fiskin A. , Melnykovych G. , Peterson G.
Published: June 2020

We have reported a technique for accurately visualizing the surface distribution of alkaline phosphatase activity in replicas of cells cultured on glass [1] and have attempted to relate changes in observed activity to exposure to glucocorticoids which reduce (line S3K) or induce (S3G) total HeLa cell culture activity. Asynchrony and the history of each cell attachment to the glass substrate appeared as sources of variability in those studies. Here we relate the sequence of morphological changes followed by HeLa cells attaching to glass to changes in surface alkaline phosphatase activity, and demonstrate conspicuous differences between the response of the two lines to glucocorticoid.

Clonal cultures grown (± dexamethasone) on coverslips were fixed briefly in buffered 2% gluteraldehyde, exposed to a Gomori type reaction mixture, rinsed and dried (critical point or air). Carbon-shadowed carbon replicas of the surface of the cultures were recovered by digestion, conserving the lead-product precipitate in situ. Surface morphology was visualized at .5μ underfocus, and the distribution of lead phosphate was recorded in near focus electronmicrographs.
Scanning Electron Microscopy (SEM) of the Endothelium of Canine Vein Segments Prepared for Surgery
Authors: Mitchener J.S. , Ratliff N.B. , Fuchs J.C.
Published: June 2020

In order to assess the integrity of large areas of endothelium in canine veins, segments have been studied by SEM. This technique enables one to accurately assess the surface morphology of relatively large areas of vein endothelium. Canine jugular veins were fixed in 4% glutaraldehyde, critical point dried in liquid CO2, and then coated with gold and palladium for SEM. Control veins (Fig. 1) revealed a flat, smooth sheet of polyhedral endothelial cells with slightly protruding nuclei and regular cell boundaries. The luminal surface was free of any defects, though occasional adherent blood cells were noted. When the vein was stripped of surrounding adventitia and left in situ with normal intraluminal blood flow for two hours (Fig. 2), there was a moderate increase in the number of blood cells sticking to the endothelial surface, but no evidence of endothelial cell sloughing or separation. Studies employing en face serial sections visualized by Nomarski differential interference contrast microscopy (DIC), and thin sections studied by transmission electron microscopy (TEM) revealed no evidence of endothelial or medial necrosis, but foci of extravasated erythrocytes and neutrophils were noted within the media of the veins from which the adventitia had been stripped.
Scanning Secondary Electron Microscopy of Myofibrils Using Transmission Techniques
Authors: Lamvik M. K.
Published: June 2020

When observing small objects such as cellular organelles by scanning electron microscopy, it is often valuable to use the techniques of transmission electron microscopy. The common practice of mounting and coating for SEM may not always be necessary. These possibilities are illustrated using vertebrate skeletal muscle myofibrils.

Micrographs for this study were made using a Hitachi HFS-2 scanning electron microscope, with photographic recording usually done at 60 seconds per frame. The instrument was operated at 25 kV, with a specimen chamber vacuum usually better than 10-7 torr. Myofibrils were obtained from rabbit back muscle using the method of Zak et al. To show the component filaments of this contractile organelle, the myofibrils were partially disrupted by agitation in a relaxing medium. A brief centrifugation was done to clear the solution of most of the undisrupted myofibrils before a drop was placed on the grid. Standard 3 mm transmission electron microscope grids covered with thin carbon films were used in this study.
Electron Probe Analysis and Ultrastructure of Cultured, Freeze Dried Vascular Smooth Muscle
Authors: Garfield R. E. , Somlyo A. P.
Published: June 2020

Electron probe x-ray microanalysis at a spatial resolution of 1000 Å or better is now feasible and has been used to demonstrate mitochondrial deposits of divalent cations in ultrathin sections of fixed tissues. Monovalent and unbound ions, however, are lost and/or translocated during chemical fixation, necessitating the use of unfixed ultrathin frozen dried sections for electron probe analysis. The use of whole, frozen-dried cultured cells for electron probe analysis is easier than cryo-ultramicrotomy and presents some advantages such as rapid freezing rates attainable and imaging at conventional (75-80 kV) voltages. Smooth muscle cells from guinea pig aortas were cultured on Formvar-coated nylon grids (Fig 1). Grids with attached cells were blotted on filter paper and plunged into liquid nitrogen and dried frozen in a vacuum evaporator.

In dried whole cells examined at 75 or 80 kV, the cell outline and processes were distinct and the nuclei and mitochondria containing electron opaque granules identifiable (Fig 2,3).
Silica Incorporation in the Cell Wall of the Singing Cell of Urtica dioica
Authors: Sowers A. E. , Thurston E. L.
Published: June 2020

Plant stinging emergences exhibit functional similarities in that they all elicit a pain response upon contact. A stinging emergence consists of an elongated stinging cell and a multicellular pedestal (Fig. 1). A recent ultrastructural investigation of these structures has revealed the ontogeny and morphology of the stinging cells differs in representative genera in the four plant families which possess such structures. A unique feature of the stinging cell of Urtica dioica is the presence of a siliceous cell wall in the apical portion of the cell. This rigid region of the cell wall is responsible for producing the needle-like apparatus which penetrates the skin. The stinging cell differentiates the apical bulbous tip early in development and the cell continues growth by intercalary addition of non-silicified wall material until maturity.

The uppermost region of the stinging cell wall is entirely composed of silica (Fig. 2, 3) and upon etching with a 3% solution of HF (5 seconds), the silica is partially removed revealing the wall consisting of individualized silica bodies (Fig. 4, 5).
Correlation Between Cellular Functions and Morphological Changes of Human Trophoblast in Vitro
Authors: Garancis John C. , Hussa Robert O. , Story Michael T. , Yorde Donald , Pattillo Roland A.
Published: June 2020

Human malignant trophoblast cells in continuous culture were incubated for 3 days in medium containing 1 mM N6-O2'-dibutyryl cyclic adenosine 3':5'-monophosphate (dibutyryl cyclic AMP) and 1 mM theophylline. The culture fluid was replenished daily. Stimulated cultures secreted many times more chorionic gonadotropin and estrogens than did control cultures in the absence of increased cellular proliferation. Scanning electron microscopy revealed remarkable surface changes of stimulated cells. Control cells (not stimulated) were smooth or provided with varying numbers of microvilli (Fig. 1). The latter, usually, were short and thin. The surface features of stimulated cells were considerably different. There was marked increase of microvilli which appeared elongated and thick. Many cells were covered with confluent polypoid projections (Fig. 2). Transmission electron microscopy demonstrated marked activity of cytoplasmic organelles. Mitochondria were increased in number and size; some giant forms with numerous cristae were observed.
Ultrastructure of Glandular Epithelial Cells in the Endometrium of the Ewe during the Estrous Cycle and Early Pregnancy
Authors: Fisher M. , Brinsfield T. H. , Hawk H. W.
Published: June 2020

Five ewes were killed on each of days 0, 10, 12, 13, 14, 15, 16 and 17 of the estrous cycle (estrous = day 0) and days 12 through 17 of pregnancy. Samples of the endometrium from each uterine horn were fixed in 3% glutaraldehyde, postfixed in 1% OSO4 in Millonig's phosphate buffer and processed for electron microscopy. Thin sections were cut from three of the blocks of embedded endometrium from each uterine horn of each ewe. Randomly selected secretory glandular epithelial cells, which could be visualized from the glandular lumen to the basement membrane, were photographed in a Philips EM 200 electron microscope. Five cells were photographed from each horn of each ewe but no more than two cells from any one block were used. Cell size, percent of the cell occupied by cytoplasm, and percent of the cytoplasmic volume occupied by mitochondria, dense bodies, lysosomes, lipid, secretory vesicles and rough and smooth endoplasmic reticulum were quantitated steriologically by the point count method.
Use of Sucrose-Glycerol Density Gradients in the Preparation of Living Cells for High-Resolution Complementary Freeze-Fractured Specimens
Authors: Steere Russell L. , Michael Moseley J. , Erbe Eric F.
Published: June 2020

Glycerol, sucrose, ethylene glycol, and other cryoprotective agents are customarily utilized in the freeze-etch and freeze-fracture procedures to prevent or reduce the size of ice crystals. Fixed tissues can usually be placed directly into the final concentration of cryoprotective agent without danger of plasmolysis. Unfixed tissues, cells, and cellular components, however, must be transferred slowly into the final concentration of cryoprotective agent if the membrane integrity is to be maintained and membrane distortions are to be avoided. In an effort to minimize such problems, we have developed a density-gradient procedure which results in the retention of structural integrity of both plant and animal tissues. This procedure involves the preparation of gradient tubes containing buffer at the top and continually increasing concentrations of cryoprotective agent to the bottom of the tube. Tissue samples or suspensions of cells or cellular components are layered on top of the gradient in the buffer and allowed to settle by gravity as the cryoprotective agent diffuses into them.
Electron Microscopy of Bacteriophage T7 Internal Head Proteins
Authors: Serwer P.
Published: June 2020

The genome of bacteriophage T7 is a duplex DNA molecule packaged in a space whose volume has been measured to be 2.2 x the volume of the B form of T7 DNA. To help determine the mechanism for packaging this DNA, the configuration of proteins inside the phage head has been investigated by electron microscopy. A core which is roughly cylindrical in outline has been observed inside the head of phage T7 using three different specimen preparation techniques.

When T7 phage are treated with glutaraldehyde, DNA is ejected from the head often revealing an internal core (dark arrows in Fig. 1). When both the core and tail are present in a particle, the core appears to be coaxial with the tail. Core-tail complexes sometimes dislodge from their normal location and appear attached to the outside of a phage head (light arrow in Fig. 1).
Ultrastructure of a Strigeoid Cercaria (Alaria) (Trematoda, Diplostomatidae)
Authors: Dernaree Richard S. , Wootton Donald M.
Published: June 2020

As a continuation of our previous studies of cercarial ultrastructure: furcocercous, longifurcate-pharyngeate cercariae identified as Alaria sp. were harvested from infected snails (Heliosoma sp.) collected near Chico, CA.

Cercariae were fixed in 2.5% Sorensen's phosphate-buffered glutaraldehyde, and then 1% osmium tetroxide in the same buffer, dehydrated in ethanol, and flat-embedded in Spurr's resin.

Both the body (Fig. 1) and the tail had pronounced filamentous surface coats. Spines were numerous on syncytial body tegument (Fig. 1) and tail furcae, but absent on the tail stem.

The circular and longitudinal muscles of the body (Fig. 1), circular and radial muscles of the ventral sucker, and excretory bladder muscles (Fig. 2) all had a "non-striated" appearance which is characteristic of slowly contracting fibers. The latter finding contrasts with the "striated" nature of oral sucker muscles in Cryptocotyle lingua. Tail muscles were striated like those of Cotylurus (another closely related furcocercous, strigeoid cercaria).
Electron Probe Analysis and Cell Physiology
Authors: Somlyo A.P. , Somlyo Avril V.
Published: June 2020

Electron probe x-ray microanalysis (EPMA) of rapidly frozen tissues is a uniquely powerful method for dealing with a large class of general problems in cell physiology, as it is suitable for measuring, under direct vision, the elemental composition of cells and cell organelles. EPMA can reach a spatial resolution of at least 10nm, and its practically attainable sensitivity (for Ca) is 0.3mmol Ca/kg dry wt. Therefore, the composition of mitochondria and of other organelles, as small as the endoplasmic reticulum (ER), can be quantitated with EPMA. The most extensive applications of EPMA to cell physiology have been in muscle physiology and epithelial transport (for reviews). In this discussion, we will illustrate the applications of EPMA by summarizing studies from our laboratory on striated and smooth muscle function. We shall also illustrate the use of EPMA to study the effects of drugs on organelles. The general applicability of EPMA to cell transport will be illustrated, somewhat arbitrarily, through EPMA studies of vertebrate photoreceptors. We are convinced that as experience is gained, largely with the specimen preparatory techniques required, EPMA will also find increasing applications to cell pathology, as illustrated by the recent demonstration of calcium compartmentalization in sickle red blood cells.
Quick-Freezing With High Time Resolution Of Fast Physiological Events
Authors: Sommer Joachim R.
Published: June 2020

Quick-freezing methodology has made three major contributions to our ability to relate structure to function: 1. Quick-freezing, especially when followed by freeze-fracture, is suited to study the ultrastructure of unfixed biological material as close to the native state as can possibly be obtained. 2. Physiological events associated with morphological changes at the level of electron microscopic resolution can be stopped at any desired time interval and, thus, analysed against a known time scale and, 3. Microchemical measurements, e.g. of elemental concentrations and their spatial displacements, can be obtained by electron dispersive X-ray microanalysis from freeze-dried frozen sections of quick-frozen biological material. Indeed, it is now possible to investigate, simultaneously, anatomical, physiological and microchemical parameters in a single cell, with a precise time scale thrown in for good measure.

In the following I shall describe the techniques that we employ to study the morphology of single intact skeletal muscle fibers of the frog at known time intervals following electrical stimulation. The methodology is the judicious extension, including some modifications, of procedures whose efficacy is mostly uncontroversial and a matter of scientific record.
Microstructural Characterization of Rapidly Solidified Carbide-Containing Ni-Base Superalloys
Authors: Hall E. L. , Jackson M. R.
Published: June 2020

The temperature capability of nickel-base superalloys which are used in aircraft turbines may be able to be extended if novel microstructures can be produced in these materials by rapid solidification. The primary goal of these efforts is to achieve a fine dispersion of small precipitates which are stable at high temperature in the alloys. One class of alloys which seem particularly promising are the eutectic superalloys, which solidify via a eutectic reaction in which a γ- γ’ matrix containing MC carbides is formed. For this investigation, alloys which contained either Ta, Ti, or V as the primary carbide former were studied. In all cases, the base alloy consisted of Ni-4%Co-4%Cr-5.5%Al-2%Mo-3%W-1.5%Re-0.3%C in weight percent. The alloys additionally contained either 9% Ta, 5.5% Ti, or 4.5% V (subsequently referred to as alloys A, B, and C, respectively). The alloys were rapidly solidified by melt-spinning in vacuum.
Electron Beam Damage in High-Temperature Polymers
Authors: Kumar Satish , Krause Stephen J. , Adams W. W.
Published: June 2020

Electron microscopy studies of polymers are limited due to beam damage. Two concerns are (i) the damage mechanism in a particular material, and (ii) the maximum dose for a material before damage effects are observed. To understand these aspects of beam damage of polymers several systematic studies have been under taken. From the knowledge of the dose required for damage to the polymer crystals, optimum parameters for electron microscopy imaging can be determined.

Electron beam damage can be quantified by changes in (i) mass, (ii) diffraction contrast, (iii) diffraction intensity, and (iv) electron energy loss spectrum (EELS) intensity. Dose required to damage a material depends on which of the above criteria is applied. Therefore to compare the beam damage results for different polymers it is necessary to use the same criteria. We have studied beam damage by measuring the loss of diffraction intensity. Diffraction intensity decreases exponentially with increasing electron dose, after a short initial period. The intensity, I(D), of a particular reflection at a dose, D, can be given by the following equation.
Forensic Examination of Bulb Filaments By the Sem
Authors: Thorsen Knud Aage
Published: June 2020

In the investigation of traffic accidents, whether auto collisions or airplane crashes, it is often very important to establish whether the headlights as well as the signal and warning system of the vehicles were on or off at the moment of the accident. Legal responsibility for the specific case may thus be assigned, and countermeasures can be taken to reduce the risk of recurrences.

Fortunately the incandescent lamps themselves, or more specific, their filaments, often give the key to clearing the case. The stresses generated on a filament by the accelerations and sudden stop of a collision, produce deformation and fracture phenomena, with characteristic differences between hot and cold filaments resulting. Further evidence may arise if the glass bulb is broken at the accident, as the tungsten metal of the filament will be oxidized if hot. Glass splinters from the broken bulb hitting a hot wire will melt in the same way.
Subcellular Ions By X-Ray Microanalysis For Evidence of Hepatotoxicity
Authors: Millette J. R. , Allenspach A. L. , Clark P. J.
Published: June 2020

The hypothesis that the influx of extracellullar Ca2+ across a damaged plasma membrane is the final common pathway for chemically mediated cell death has stirred considerable controversy and continued interest in the study of subcellular ion shifts as sensitive indicators of hepatotoxicity caused by environmental pollutants. A number of studies have shown that increases in hepatic mitochondrial calcium result from the ingestion of carbon tetrachloride. Quantitative measurement of calcium in subcellular components was accomplished in early studies by using techniques involving whole tissue homogenation and fractionation by centrifugation. In this study x-ray microanalysis of quick-frozen liver tissue, cryo-sectioned for the electron microscope, provided an alternative approach to studying subcellular ion distribution.
Analysis of Biological Elements of Scalp Hairs With Sem-Edx and Tem and its Application to the Hair Comparison
Authors: Seta S.
Published: June 2020

Personal identification of hair samples collected from the crime scene has been principally made on basis of precise comparison of morphological features and the result of blood grouping of hair samples. For the present only ABO blood types can be routinely examined on hair samples, and therefore, other additional informations for the hair comparison have long been required, among which the trace element composition of hairs has been utilized as giving a clue to the hair comparison. Here, scanning electron microscope equipped with energy dispersive X-ray microanalyzer (SEM/EDX), which has been widely used to examine many kinds of physical evidences in forensic laboratories, was applied to the elemental analysis of hairs. Since SEM/EDX enables us to analyze very small amount of sample, it is very efficient in the hair comparison in which each single hair strand collected from crime scenes has its own evidential value. But SEM/EDX analysis of hairs involves the intrinsic problem that trace elements other than sulfur and chlorine are very hard to detect from raw hair samples.
Aberration-Correcting Properties of the Hyperbolic Electron Mirror
Authors: Rempfer F. F. , Mauck M. S.
Published: June 2020

Spherical and chromatic aberration are inherent in electron lenses. Under certain conditions the possibility exists that these lens aberrations can be eliminated or compensated. The conditions under which such corrections are possible (in principle) have been characterized originally by Scherzer and later by Septier. One type of correcting system involves the use of an electrostatic electron mirror. The work presented here deals with the properties of hyperbolic electron mirrors and the conditions for matching the correcting properties of a mirror to the spherical and chromatic aberration of a lens or lens system.

In an earlier work by the authors, the properties of the hyperbolic mirror were studied for rays incident on the mirror parallel to the optical axis. In the present work, symmetrical rays are studied.
Sensitivity-Enhanced Interference Electron Microscopy
Authors: Osakabe N. , Endo J. , Matsuda T. , Kawasaki T. , Tonomura A.
Published: June 2020

Interference electron microscopy by holographic reconstruction has been applied to many fields: An interferogram of a specimen having nonunifom thickness can be interpreted as a thickness contour map. In case of a ferromagnetic thin film, contour lines in an interferogram follow the magnetic lines of force. The contour interval of a phase-shift ƛ (ƛ is an electron wave length) correspons to a thickness of 2 ϕ0 ƛ/V0 (V0 is the mean inner potential and ϕ0 is the accererlating voltage) and a magnetic flux of h/e (= 4.1X10—15 Wb) respectively. For detailed observation such as that of atomic scale thickness variation or weak magnetic fields from single domain fine particles, electron phase shifts recorded in a hologram has to be amplified. In recent experiment conducted by authors, interferograms phase amplified 10 times were obtained. The method employed a higher-order diffracted beam and its conjugate utilizing the film's nonlineality. However the phase amplification of factor 10 is not sufficient for the above purposes. In the present experiment, successful attempt to detect an electron phase shift of order ƛ /100 was made using another phase-amplification technique introduced by Bryngdahl and improved by Matsuda.
Energy-Dispersive Spectroscopy in A 400Kv Electron Microscope
Authors: S. Suzuki  , Y. Bando  , H. Kitajima  , T. Honda  , Y. Harada  , M. Kersker
Published: June 2020

A Si(Li) detector for X-ray energy dispersive spectroscopy (EDS) has been installed on a 400 kV EM, the JEM-4000EX, which is also interfaced with a scanning device (ASID40) and electron energy loss spectrometer (ASEA40). The EM's basic performance, i.e., resolving power, is 0.23 nm at 400 kV. X-ray microanalysis in a high-voltage EM has many advantages, but few reports have been published because of some severe instrumental problems originating from it's high energy electron beam. To overcome these problems many modifications have been made on the EM column.

The modifications are divided into two aspects. One is the reduction of bremsstrahlung and the other is the protection of the Si(Li) detector from hard X-ray radiation from the upper parts of the detector, especially condenser lens (CL) aperture. To reduce bremsstrahlung many parts of the wall which electron beam might hit are covered with graphite and the materials for CL fixed apertures are changed to light elements. To protect the detector X-ray shielding parts made of heavy metals (W, Ta, Pb) and with a total thickness of more than 30 mm are set between the CL aperture and the Si(Li) detector.
Current Status of Solid-State X-Ray Systems
Authors: Peckerar Martin , Tousimis Anastasios
Published: June 2020

Solid state x-ray sensing systems have been used for many years in conjunction with scanning and transmission electron microscopes. Such systems conveniently provide users with elemental area maps and quantitative chemical analyses of samples. Improvements on these tools are currently sought in the following areas: sensitivity at longer and shorter x-ray wavelengths and minimization of noise-broadening of spectral lines. In this paper, we review basic limitations and recent advances in each of these areas. Throughout the review, we emphasize the systems nature of the problem. That is. limitations exist not only in the sensor elements but also in the preamplifier/amplifier chain and in the interfaces between these components.

Solid state x-ray sensors usually function by way of incident photons creating electron-hole pairs in semiconductor material. This radiation-produced mobile charge is swept into external circuitry by electric fields in the semiconductor bulk.
Comparison of Ion-Milling Techniques For Cross-Sectional TEM of Semiconductors
Authors: Luck Julia T. , Boggs C. W. , Pennycook S. J.
Published: June 2020

The use of cross-sectional Transmission Electron Microscopy (TEM) has become invaluable for the characterization of the near-surface regions of semiconductors following ion-implantation and/or transient thermal processing. A fast and reliable technique is required which produces a large thin region while preserving the original sample surface. New analytical techniques, particularly the direct imaging of dopant distributions, also require good thickness uniformity. Two methods of ion milling are commonly used, and are compared below. The older method involves milling with a single gun from each side in turn, whereas a newer method uses two guns to mill from both sides simultaneously.
Examination of Intergranular Attack in Alloy 600 Tubing: Pneumatic Expansion to Separate Grains
Authors: Gibbon Donald L.
Published: June 2020

Severe intergranular attack (IGA) has occurred in Ni-based Alloy 600 under some use conditions, degrading as much as 40-60% of the wall thickness in heat exchanger tubes. In order to understand the IGA process more thoroughly, it was necessary to examine pristine samples of the attacked grain surfaces. Any preparation that involved use of liquids was ruled out because of possible contamination or removal of important constituents; ion-thinning for transmission electron microscopy would be difficult because of the extremely poor bonding between the grains in the IGA areas; simple fracture would be difficult because of the extremely plastic behavior of Alloy 600 (even at LN temperatures) and because of the irregular distribution of the attacked areas. The following preparation technique met all of these objections and even turned some of them into advantages.
Microscopic Investigation of Nb Filaments In In Situ Superconducting Wire
Authors: Cheng C. C. , Laabs F. C. , Pelton A. R. , Verhoeven J. D.
Published: June 2020

In-situ processing is one of the most interesting approaches for fabricating multifilamentary Nb3Sn-Cu superconducting wire for large scale application. In the initial stage of this fabrication process, the desired weight fraction of Nb dendrites is formed in a Cu matrix. Subsequent processing steps include wire drawing and reaction with Sn to produce the Nb3Sn superconducting phase. The distribution and morphology of this phase determines the ultimate properties of the composite wire. It is therefore of interest to determine: the effects of processing on the development of Nb filaments and (2) how these parameters affect the precipitation of Nb3Sn. Thus, the purpose of this paper is to report the results from a SEM and TEM study of Nb filaments in unreacted Cu-Nb wire.
Electron Microscopy in the Study of Magnetic Materials
Authors: Grundy P.J.
Published: June 2020

The aim of this paper is to highlight in brief two main areas in recent electron microscope studies of magnetic materials. The first is in detailed micromagnetic investigations of a fundamental kind and the second is the observation and characterisation of magnetic properties, magnetic domain structure and microstructure in technically important materials. Detailed quantitative investigations of micromagnetic features have, of necessity, been confined to specialist techniques of Lorentz microscopy (LEM). However, conventional modes of TEM and SEM, and X-ray microanalysis complement the defocussed or Fresnel mode of LEM in giving a detailed characterisation of iragnetic materials. It is in this context that LEM has found the widest application.
The Microstructure of Melt-Spun Iron Neodymium Permanent Magnet Materials
Authors: Dickenson R. C.
Published: June 2020

Rapidly-quenched iron rare-earth boron alloys, with appropriate heat treatment, exhibit commercially promising permanent magnetic properties. This paper will report the results of an AEM characterization undertaken to explain the origin of the magnetic properties of an iron-neodymium-boron alloy in terms of its microstructure. Ribbons of Fe76 Nd16 B8 were prepared by melt-spinning, and were subsequently annealed at 700°C for 6 minutes to promote growth of a fine-grained structure. Samples were prepared for AEM by ion-milling the ribbons on a cold stage and examined using a Philips 400T TEM/STEM equipped with an energy dispersive x-ray unit.

Three different microstructures are commonly observed in these alloys, and several others have been found in isolated cases.
Bacterial Trace Fossils in Eocene Kaolin
Authors: Barker W. W.
Published: June 2020

Spheroidal electron-dense masses averaging two microns in diameter comprise up to 20% of a thin Eocene grey kaolin in the upper part of the Huber Fm. near Wrens, Georgia. TEM and SEM reveal that the microspheroids consist of tangentially oriented kaolinite platelets enclosing much finer, delicate intergrowths of secondary authigenic minerals.

Many types of bacteria and algae produce mucopolysaccharidal exudates which can attach clay platelets. Clay-clad microorganisms are especially common in marine and estuarine environments, where high ionic strength compresses the electric double layer of kaolinite sufficiently for van der Waals forces to aid its attachment to exudates. Maclean and Smart found clay-clad prokaryotic cells in recent estuarine sediments. Avnimelech, et al. demonstrated mutual flocculation of algae and clay upon addition of electrolyte. Because the size and structure of the clay-clad microspheroids in the Eocene kaolin closely resembles the clay-clad bacteria in recent marine muds, they are interpreted as trace fossils of bacteria.
The Effect of Coherent Bremsstrahlung Peaks in AEM Studies of Grain Boundary Segregation
Authors: Vecchio K. S.
Published: June 2020

Recently coherent bremsstrahlung (CB) peaks have been detected in x-ray spectra in the analytical electron microscope (AEM). It has been suggested that CB peaks, which are Gaussian, may either mask, or be misinterpreted as elemental peaks in x-ray spectra. A method for identifying and isolating these peaks has been presented, The problem of CB peaks is particularly severe in AEM grain boundary segregation studies, because the amount of segregant in the interaction volume is small (<∼3 wt%), the x-ray counting times are long, and as a result the CB peak intensities can approximate to the expected segregant peak intensity. The misleading effects of CB can be either to produce pseudo-element peaks close to true element peak positions, or to overestimate the true element peak intensity when the CB peaks are superimposed on the x-ray peak of the segregant. This article reports an investigation of the effects of CB on segregation studies in Cu and Fe.
Surfaces and Surface Rearrangements at Atomic Resolution
Authors: Smith David J. , Bursill L.A. , Marks L.D. , Lin Peng Ju
Published: June 2020

With proper operating conditions and suitable specimens, it is possible with the latest HREMs to obtain atomic-level information from surface profile images. In this paper, we describe recent observations of metal and oxide surfaces, including atomic rearrangements, using the JEOL 4000EX at Arizona State University. This microscope, which is equipped with a top-entry, double-tilt, ultra-high-resolution specimen stage, bettered the guaranteed resolution figure of 1.8A during installation. It is therefore an ideal instrument for investigating surface morphology at atomic resolution.

Gold surfaces

Our original objective was to further our previous observations of atomic rearrangements on extended Au surfaces by imaging in the novel (100) projection. Although this requires a resolution of better than 2.0A, it is possible to observe, as shown in Fig. 1, details of the surface morphology including surface steps, facetting and the presence of adatoms. Moreover, when cleaned of carbon, it is found that substantial atomic motion occurs along the surface and videotape recordings are now being analysed to establish whether there is any correlated motion of atomic columns.
Reaction Products of Cathodically Protected Steel in Soil
Authors: Moore T. J.
Published: June 2020

Cathodic protection is employed in soils to reduce the corrosion sustained by metallic structures in aggressive soil environments. This study is designed to investigate the mechanisms of cathodic protection :n soils by observing the solid phase products which precipitate as a result of these reactions.

Cathodic protection of mild steel specimens was monitored using sacrificial magnesium anodes placed in two soils at four depths. After a period of one year, the samples were retrieved, vacuum dried, and subjected to scanning electron microscopy, electron microprobe analysis, and x-ray diffraction.

The solid phases precipitated at the soil/metal interface may be categorized into two groups: 1) A thin coating of iron oxides and 2) A thicker layer of magnesium salts.
Analytical Electron Microscopy of Ion-Implanted Metals
Authors: Potter D.I. , Ahmed M. , Ruffing K.
Published: June 2020

Ion implantation, used extensively for the past decade in fabricating semiconductor devices, now provides a unique means for altering the near-surface chemical compositions and microstructures of metals. These alterations often significantly improve physical properties that depend on the surface of the material; for example, catalysis, corrosion, oxidation, hardness, friction and wear. Frequently the mechanisms causing these beneficial alterations and property changes remain obscure and much of the current research in the area of ion implantation metallurgy is aimed at identifying such mechanisms. Investigators thus confront two immediate questions: To what extent is the chemical composition changed by implantation? What is the resulting microstructure? These two questions can be investigated very fruitfully with analytical electron microscopy (AEM), as described below.
Microstructure of TiC Layers on Iron and Carbon Steel Formed By Elevated-Temperature Ion Implantation
Authors: Sprague J. A.
Published: June 2020

In several previous investigations, it has been shown that the implantation of carbon-active elements such as Ti, Hf, Ta, and Nb into Fe or steel specimens can produce low-friction, wear-resistant surface layers, provided that the implanted element is chemically bound to a sufficient concentration of carbon. For the case of room-temperature implants, the source of the carbon can be either a directly implanted layer or carbon that is adsorbed from the residual atmosphere of the target chamber. For these room-temperature implants, the surface layers consist of an amorphous Fe-Ti-C alloy. In more recent work, it was observed that the implantation of 5 x 1017 Ti/cm2 at 190 keV into Fe or carbon steels at temperatures between 600 and 800°C produced a near-stoichiometric crystalline TiC layer, approximately 60 nm thick, which was continuously graded in composition into the substrate. For pure Fe, the source of the carbon was shown to be the residual atmosphere, while for steels containing greater than 0.1 wt.% C, the source was the C in the alloy.
Ion Beam Mixing of Ni-Ti Bilayered Thin Films
Authors: Rai A. K. , Bhattacharya R. S. , Rashid M. H.
Published: June 2020

Ion beam mixing has recently been found to be an effective method of producing amorphous alloys in the binary metal systems where the two original constituent metals are of different crystal structure. The mechanism of ion beam mixing are not well understood yet. Several mechanisms have been proposed to account for the observed mixing phenomena. The first mechanism is enhanced diffusion due to defects created by the incoming ions. Second is the cascade mixing mechanism for which the kinematicel collisional models exist in the literature. Third mechanism is thermal spikes. In the present work we have studied the mixing efficiency and ion beam induced amorphisation of Ni-Ti system under high energy ion bombardment and the results are compared with collisional models. We have employed plan and x-sectional veiw TEM and RBS techniques in the present work.