bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nucleation of Indium Atoms on an Amorphous Carbon Substrate
Authors: Snipes J. , Ohtsuki M. , Utlaut M. , Crewe A. V. 
Published: June 2020

The motion of indium atoms on a thin (∼15 Å) amorphous carbon film was followed over a period of 14 days using a high resolution STEM. Indium was chosen because it nucleates rapidly in comparison with other atom species that have been observed (e.g., Ag, U, Pt, and Pd). A previous study showed that the effect of the electron beam on the motion of the deposited atoms was negligible, so that the observed nucleation is predominantly a diffusion process.The indium atoms were evaporated onto the substrate. The specimen was then placed in the microscope and kept under vacuum at room temperature throughout the study. Micrographs were taken at daily intervals, digitized, and stored on magnetic tape for retrieval with a computer and image processor. All micrographs were taken at an electron energy of 31 keV (Fig. 1).
Anomalous Weak Beam Contrast from Extrinsic Stacking Faults
Authors: Shaw M.P. , Self P.G. 
Published: June 2020

This paper concerns observations of anomalous fault contrast arising from weak beam images of extrinsic faulted dislocation loops. Weak beam images are of considerable use when examining lattice defects due to the reduced image width associated with dislocations and the fine detail revealed in the fringe contrast from stacking faults. The observations described here arose from a study of interstitial (extrinsic) dislocation loops produced by radiation damage in a commercial nickel base superalloy, Nimonic PE16(1).Figure 1 shows a bright field image revealing faulted loops on all four {111} planes of the f.c.c. structure. Complementary images taken in a variety of different two beam diffracting conditions showed the faulted loops to be <111> interstitial faults surrounded by <111> pure edge (Frank) partial dislocations. When images were taken under weak beam conditions, contrast from the stacking faults was found to be critically dependent on the sign of g.R (where g is the diffracting vector and R the displacement vector of the fault).
EELS Measurements of Carbon and Nitrogen in V(CN) Precipates from HSLA Steel
Authors: Garratt-Reed Anthony J. 
Published: June 2020

The technique of carbon extraction replication has enabled many workers to obtain useful data on the composition of a variety of precipitates in alloys. When the available analytical method (energy-dispersive X-ray spectroscopy) was limited to detect only those elements heavier than neon the presence in the specimen of the carbon of the replica was not objectionable. With the development of methods to analyze for light elements, such as electron energy-loss spectroscopy (EELS), or energy dispersive X-ray spectroscopy with an ultra-thin window detector occasions arise when analysis for carbon is indicated. In such cases carbon extraction replication is clearly inappropriate.In the present project it was required to study the precipitation of vanadium, presumed to be in the form of carbonitrides, in vanadium HSLA steel. Of particular interest was the ratio of carbon to nitrogen as a function of the specimen history and initial composition. Replicas were therefore made using aluminum.
Rapid Recording of Microdiffraction with a STEM Instrument
Authors: Cowley J. M. 
Published: June 2020

The optical system attached to our HB5 STEM instrument acts as an efficient two-dimensional detector system which allows microdiffraction patterns from regions 10Å or less in diameter to be recorded at TV rates. Replaying the patterns from single video-tape frames allows us to study transient phenomena and to overcome to some extent the limitations due to the mechanical and electrical instabilities which often induce relative movements of the electron beam and the specimen of the order of 1Å over periods of a fraction of a second.This rapid recording has made it possible for microdiffraction patterns to be obtained from regions of less than 20Å in diameter selected from images of a highly disordered kaolinite sample which is very sensitive to radiation damage. When the electron beam is stopped at a position chosen by a marker in the bright field image, the diffraction pattern fades out in about 0.1 secs, but several single frames of the videotape provide good records such as that of figure 1(a).
Microdiffraction in Dedicated STEM
Authors: Houghton D.C. 
Published: June 2020

Microdiffraction in dedicated STEM instruments has shown considerable promise as a source of microanalytical information. A major problem has been the relatively inefficient sequential methods used to obtain the diffraction pattern. The apparatus shown schematically in Fig. 1 has facilitated parallel viewing and recording of diffraction patterns in the HB5 STEM. The equipment is robust, low cost and can be installed with no modifications to the microscope.A series of diffraction patterns were recorded under identical conditions at a (110) zone axis in an Al-4% Cu foil shown in Fig. 2(a) to allow direct comparison of sequential and parallel recording methods. The thickness in this part of the foil was ∼220 nm as measured from the projected widths of θ' plates. The selected area “rocking beam” images in Figs. 2(b) and (d) are clearly noisy, suffer from scan distortions and their usefulness for phase identification and crystal orientation is severely limited.
Experiments with an Imaging Filter in a CTEM
Authors: Krahl D. , Herrmann K.-H. , Zeitler E. 
Published: June 2020

The installation of an imaging energy filter extends the imaging and analytical capabilities of a conventional transmission electron microscope (CTEM) considerably. We report here on experiments which demonstrate the versatility of such a device. The arrangement of our system is shown in Fig. 1. The experiments performed pertain to:The improvement of contrast in thick specimens by exclusion of inelastically scattered electrons. The spatial resolution of the electron microscope can be preserved by the correction of second-order aberrations with additional electromagnetic hexapoles.The determination of the concentration of light elements with EELS at a spatial resolution better than 10 nm. The chemical structure of ceramic material (SI3N4and SiC with additions) could thus be elucidated. A study on the extended fine structure in the energy loss spectra of the oxygen and magnesium K edges in MgO (Fig. 2) did confirm the theoretical prediction for that material.
Analytical Electron Microscope Evacuated by Perfect Dry Pumping System
Authors: Harada Y. , Ishida Y. , Arai Y. , Ooi K. , Obara Y. 
Published: June 2020

Analytical electron microscopes (AEM), which provide the functions of transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and electron energy loss spectroscopy, have been in practical use to analyze elements in microareas. Meanwhile, surface studies have recently been conducted with an ultrahigh vacuum (UHV) electron microscope by utilizing reflection electron microscopy including the reflection high energy electron diffraction method. We have developed an ultrahigh vacuum analytical electron microscope (UHVAEM) aimed at surface studies.The present paper describes the outstanding features of the UHVAEM. Fig. 1 shows the schematic diagram of its vacuum system. The specimen and gun chambers are evacuated by a sputter ion pump (SIP) after being rough pumped by a turbo molecular pump (TMP). The viewing and camera chambers which have much out-gas from photographic films are evacuated by the TMP. The image forming lens system is designed to provide constant projector lens excitation over the entire magnification range.
Development of the Cryo Pump System for Electron Microscope
Authors: Iwatsuki M. , Venuti Guy 
Published: June 2020

In proportion, as the electron microscope expands the field as an analytical instrument, the problems of specimen contaimination will become more critical. Also, emission instability and short life of the LaB6 tips depend on the ultimate vacuum pressure in the gun chamber (particularly, due to the partial pressure of oxygenized molecules). Meanwhile, as scanning electron microscopes are utilized as a means for quality control in the semi-conductor field, as well as for analysis, the problems with specimen contamination will become more prominent.Today, DP-RP type pumps are widely used as high vacuum pumps in scanning electron microscopes. However, due to the oil used in these pumps, back-streaming occurs, causing specimen contamination. In contrast to this wet vacuum system, ion pumps, Ti-sublimation pumps, and Turbo-molecular pumps, etc. have been utilized as dry vacuum systems. Among these dry pumps, ion pumps and Ti-sublimation pumps are most popular as a means of obtaining ultra high vacuum. Also, Turbo-molecular pumps are widely used for scanning electron microscopes.
Generation and Storage of SEM or STEM Intensity Profiles on a Multi-Channel Analyzer
Authors: Owen R. T. , Madden M. M. , Bates S. R. 
Published: June 2020

Using an SEM for quantitative analysis often requires intensity profiles along a single scan line. These profiles are usually obtained by either: 1) selecting a scan line from the CRT display, switching to Y-modulation and photographing the displayed intensity profile, or 2) scanning the negative of a photograph of the entire CRT display along a line using a microdensitometer. The first method requires additional measurements of the CRT beam deflection to get quantitative information, and thus has limited accuracy. The second method places another interface between the measurement and the detector signal.For SEMs or STEMs equipped for energy dispersive x-ray analysis with a multichannel analyzer (MCA) and minicomputer, modifications can be made to the circuitry to allow digital recording of line scan intensity data directly with the MCA.
Bluetongue Virus Infection in Salivary Glands of Culicoides Variipennis
Authors: Foster Neil M. , Jones Robert H. 
Published: June 2020

Bluetongue virus (BTV) multiplies in the invertebrate host culicodies variipennis and is transmitted by this biting fly to wild and domestic ruminants; e.g., see review. Virus replication in the salivary gland of nonbloodfed flies was similar to that for cultured cells. This report describe observations on BTV-infected salivary gland cells from bloodfed flies.Two-day-old female flies, which had been given a blood meal on normal rabbits when the flies were one day old, were inoculated either with normal or BTV-infected cell culture fluids into the hemocoel. Flies were maintained alternately on water and 10% sugar solution for 14-21 days when salivary glands were removed and processed for viewing in thin section.Viroplasms in association with macrotubules, fibrils, and progeny virions were observed in the cytoplasm of infected salivary gland cells (Fig. 1). Large numbers of macrotubules were observed and they often occupied large areas of the cell. Macrotubules most often appeared in bundles of linear array and had an ordered appearance.
Immunologic Localization of Murine Leukemia Virus Antigens in Thin Sections
Authors: Weigand Ray A. , Paquette Carol I. , Longley Clifford , Furmanski Philip 
Published: June 2020

In order to examine the temporal sequence of intracellular events which culminates in the release of infectious virus particles from the cell surface, we have developed immunoferritin techniques to localize viral antigens in thin sections. We previously described the intracellular localization of murine mammary tumor virus p28 protein in thin sections using an unlabelled antibody procedure with ferritin-antiferritin. We now describe the labelling of murine leukemia virus (MuLV) in thin sections using anti-MuLV and Protein A-ferritin.Cultures of F-MuLV in NIH/3T3 cells were grown to 90% confluence, fixed, dehydrated, and embedded in Epon as before. Thin sections were picked up on nickel grids, incubated in 20% H2O2 for 20 min, rinsed in PBS, and subjected to the labelling procedure. The labelling protocol included: preincubation in 5% BSA in PBS, rinse in 1% BSA in PBS, 3 hour incubation in rabbit anti-MuLV, rinse in 1% BSA in PBS, incubation in apoferritin, incubation in Protein A-ferritin (Zymed Labs., Burlingame, CA), rinses in 1% BSA in PBS and PBS, and incubation in 2% glutaraldehyde in PBS.
Effect of Iron Limitation on the Ultrastructure of Agmenellum Quadruplicatum
Authors: Hardie L. P. , Balkwill D. L. , Stevens S. E. 
Published: June 2020

Agmenellum quadruplicatum is a unicellular, non-nitrogen-fixing, marine cyanobacterium (blue-green alga). The ultrastructure of this organism, when grown in the laboratory with all necessary nutrients, has been characterized thoroughly. In contrast, little is known of its ultrastructure in the specific nutrient-limiting conditions typical of its natural habitat. Iron is one of the nutrients likely to limit this organism in such natural environments. It is also of great importance metabolically, being required for both photosynthesis and assimilation of nitrate. The purpose of this study was to assess the effects (if any) of iron limitation on the ultrastructure of A. quadruplicatum. It was part of a broader endeavor to elucidate the ultrastructure of cyanobacteria in natural systemsActively growing cells were placed in a growth medium containing 1% of its usual iron. The cultures were then sampled periodically for 10 days and prepared for thin sectioning TEM to assess the effects of iron limitation.
Ultrastructural Aspects of the Aecial, Uredial and Telial Stages of Puccinia Asparagi DC
Authors: Baker Karen K. 
Published: June 2020

Puccinia asparagi DC is a macrocyclic, autoecious rust occurring on Asparagus officinalis. The most apparent manifestations of the disease are the aecial pustules on the stalks in the spring and the uredial and telial pustules on the fern stems during the summer. Pycnia are inconspicuous and were not observed in the first year of this studyAecidioid aecia occur in groups on stems (Fig. 1). Hyphae is both inter- and intra-cellular. Aecia have a well-defined peridium, 1 cell layer thick. Aeciospores are binucleate (Fig. 2) and finely verrucose. Verrucae are electron transparent in ultrathin sections. Wedge-shaped disjunctor cells separate the aeciospores.Uredia occur on the stems of the fern growth during the summer. The pustules are subepidermal and erumpent. Urediospores are pedicillate early during development and at maturity are echinulate (Fig. 3) with 4 equatorial pores. Echinulations are electron transparent in ultrathin sections.
Electron Microscopic and Optical Diffraction Analyses of Crystalline Intranuclear Inclusions in Human Osteosarcoma Cells
Authors: Yasuzumi Gonpachiro 
Published: June 2020

The fine structure of the crystalline intranuclear inclusions in the human osteosarcoma cells was studied by using a goniometer which tilted the specimen at angles of ±30° and ±40°. The results appear in the series of micrographs showing Fig. 1. At the point by the arrow, a helical structure is visible in two filaments. Optical diffrection patterns of selected areas of each negative electron micrograph film were taken by using a helium-neon laser as a source.A tentative model of the structure can be based on optical diffraction techniques applied to electron micrographs taken at different tilt angles. The diffraction pattern taken from image No. 0 in Fig. 1 is depicted in Fig. 2. Diffraction patterns from Nos. 3, 4 and 8 are shown in Figs. 3, 4 and 5. The contrast of some periodic structures can be eliminated in the image (extinction effect due to Bragg reflection of electron waves) by the interference of scattered waves from constituent elements. Hence it is rather important to interpret the electron micrographs and their optical diffraction patterns by considering the extinction effect of the image contrast.
Stereoscopic Visualization of Spermidine-DNA Torus Structure Prepared by the Freeze-Fracture, Deep-Etch Technique
Authors: Ruben George C. , Marx Kenneth A. , Reynolds Thomas C. 
Published: June 2020

Freeze-fracture TEM has been used to visualize spermidine-DNA complexes╌a model system for bacteriophage DNA packaging. We have observed the toroidal shape and bacteriophage size (770Å) of spermidine-condensed DNA particles prepared by quick freezing of DNA-spermidine solutions followed by a freeze-fracture, deep-etching technique. Single direction shadowing with low Pt-C metal levels (9Å thick) has allowed us to demonstrate that the freeze-fracture technique is capable of revealing the organization of separate double helical DNA strands on the torus surface. The spermidine-DNA toruses exhibited surface Pt-C decoration consistent with the DNA double helix being circumferentially wrapped to form the torus. In addition, we have demonstrated that a hydrated sample shows the same toroidal shapes that have been previously demonstrated by Chattoraj et. al, in a dehydrated preparation.We performed freeze-fracture TEM studies of spermidine condensed (0.2 mM) Calf Thymus DNA (5 μg/ml) complexes in 1 mM NaCl, 10 mM Tris pH 7.0. Samples were freeze-fractured and etched for 13 min at -97°C.
Position of Histone Pairs: H3, H4 and H2A, H2B Within the Nucleosome
Authors: Stoeckert C. , Beer M. , Wiggins J.W. , Hjelm R.P. 
Published: June 2020

The genetic material of eukaryotes is organized into nucleosomes. These consist of 145 base pairs of DNA and 2 each of the histone proteins: H2A, H2B, H3 and H4. Studies by Finchet al(1977) and Dubochetet al(1978) indicate that the shape of the nucleosome is a flat cylinder with a diameter of 110Å and a height of 55Å. Models based on histone-DNA and histone-histone cross-linking have been proposed by Kluget al(1980) and Carteret al(1980). Here we report a direct determination using the Johns Hopkins scanning transmission electron microscope (STEM) (Wigginset al, 1979).In order to identify a histone, it was labeled with several platinum atoms in a two-step procedure. The first is modification of the histone lysines with methyl (methyl-thio-acetimidate). This reaction was done on 0.3 mgs/ml in nucleosome protein in 0.6 M NaCl, 20mM Na borate pH 9.4. An imidate conc. of 40mM modifies about 50-60% of the lysines. The result is to provide thioether groups for subsequent platinum binding.
The Ultrastructure of Lymphocytic Hypophysitis
Authors: Asa S.L. , Kovacs K. , Bilbao J. M. , Josse R. G. , Kreines K. 
Published: June 2020

Seven cases of lymphocytic hypophysitis in women have been reported previously in association with various degrees of hypopituitarism. We report two pregnant patients who presented with mass lesions of the sella turcica, clinically mimicking pituitary adenoma. However, pathologic examination revealed extensive infiltration of the anterior pituitary by lymphocytes and plasma cells with destruction of the gland. To our knowledge, the ultrastructural features of lymphocytic hypophysitis have not been studied so far.For transmission electron microscopy, tissue from surgical specimens was fixed in glutaraldehyde, postfixed in OsO4, dehydrated and embedded in epoxy-resin. Ultrathin sections were stained with uranyl acetate and lead citrate and examined with a Philips 300 electron microscope.Electron microscopy revealed adenohypophysial cells of all types exhibiting varying degrees of injury. In the areas of most dense inflammatory cell infiltration pituitary cells contained large lysosomal bodies fusing with secretory granules (Fig. 1), as well as increased numbers of swollen mitochondria, indicating oncocytic transformation (Fig. 2).
High Resolution X-Ray Contact Microscopy of Hydrated Muscle Filaments
Authors: Panessa B.J. , Dewey M.M. , Brink P. , Gaylinn B. , McCorkle R.A. , Coleman G. , Warren J.B. 
Published: June 2020

Soft x-ray contact microscopy is a relatively new method for imaging biological materials at resolutions of 5-30 nm. By using a wet cell, and flash x-ray source to reduce the exposure time, we have been able to obtain high contrast images of hydrated biological specimens at better than 30 nm resolution. This paper describes the technique and results of using this type of “wet” microscopy for the examination of hydrated invertebrate isolated myosin filament, and paramyosin paracrystal,preparations.Paramyosin paracrystals and myosin filaments were isolated from telson muscle of the horseshoe crab, Limulus polyphemus L. The muscle was homogenized and the cellular debris and filaments segregated by differential centrifugation. Isolated filaments were resuspended in buffer (Tris, pH 7.4-7.5), and dialyzed overnight against buffer containing EDTA at 4°C. Tissue taken from the white adductor muscle of the clam, Mercenaria mercenaria, was similarly homogenized and isolated by standard methods.
Scanning Electron Microscopy of the Polycystic Ovary in Constant Light Rats
Authors: Singh K. B. , Khosho F. K. 
Published: June 2020

Exposure of female rats to continuous light eventually induces persistent estrus (PE), a syndrome which in many respects resembles the human polycystic ovary syndrome. Light microscopic studies on the polycystic ovaries of constant light PE rats have been previously reported. In the present study, we have utilized scanning electron microscopy (SEM) to provide information regarding three-dimensional changes occurring on the surface of the polycystic ovary.Following exposure to continuous light for 50 days, PE was induced in a group of Sprague-Dawley female rats according to the procedure described elsewhere (2). Polycystic ovaries from constant light PE rats and ovaries from controls were fixed in 2.5% glutaraldehyde in 0.1M Na cacodylate buffer, pH 7.3 at room temperature for 24 hours. They were then cut into two equal halves along their long axis and fixed for an additional 3-4 hours. The specimens were processed for SEM studies by a modified OTOTO technique, dehydrated and critical point dried with CO2.
Hepatic Lipid Accumulation and Intracellular Cholesterol Crystal Formation in Hypercholesterolemic Diabetic Rats
Authors: Handley Dean A. , Chien Shu , Arbeeny Cynthia M. 
Published: June 2020

Hypercholesterolemia, induced by feeding rats a diet of cholesterol and cholic acid, can be markedly accentuated by diabetes, resulting in serum cholesterol levels greater than 1000 mg/dl and extensive accumulate of cholesterol in the liver. To examine the cellular events of hepatic cholesterol accumulation in cholesterol-fed diabetic rats, we used a fixative containing digitonin and water-soluble embedment to preserve native lipid structures.Sprague Dawley male rats were made diabetic by intravenous injection of streptozotocin (45 mg/kg body weight) and fed a powdered diet containing 2% cholesterol, 10% lard and 1% cholic acid (CLC) for 3 wk. Non-diabetic rats were also fed CLC diet. Cholesterol, glucose and insulin levels were monitored for both groups. Livers were fixed by perfusion with 3% glutaraldehyde (30°C) and 0.2% digitonin in cacodylate buffer (1 hr), then by 1% OsO4 in buffer for 2 hr. Staining was in 2% uranyl acetate and embedding in water soluble urea glutaraldehyde. Thin sections were stained with lead citrate and viewed in a Zeiss EM-9S.