bluuebunny/crossref_metadata_2025_split huggingface dataset:
Giant Mitochondria in Skeletal Muscle of the Rat Soft Palate
Authors: Leeson C. R. , Leeson T. S. 
Published: June 2020

The soft palate of the rat contains a core of skeletal muscle in which there is a mixture of two distinct fiber types, red and white. In general white fibers have a greater diameter than red fibers and show a greater concentration of myofibrils and fewer mitochondria. The most conspicuous feature of red fibers is the presence of numerous mitochondria, which occur in two principal sites. They are present as chains running longitudinally amongst myofibrils and as marked, irregular accumulations beneath the sarocolemma. The present study concerns the subsarcolemma1 mitochondria which possess three features of particular interest.Firstly, the mitochondria show a considerable variation in size and gigantic forms are seen frequently (Fig. 1). The latter can be identified readily when scanning at low magnification. They are more or less spherical in form and thus usually appear as circular profiles on electron micrographs, unlike the mitochondria found between myofibrils which often are markedly elongated. Gigantic mitochondria have been reported previously in the myocardium of the hummingbird.
Three-Dimensional Images of Proximal Tubular Cells and The Adjoining Peritubular Capillaries
Authors: Leak L.V. 
Published: June 2020

The topographical relationships of adjacent tubular cells and blood capillaries have been studied from serial sections of both light microscopic and ultrathin sections. However, a direct observation of three dimensional images of kidney tubular cells and the adjoining peritubular capillaries has not been reported. The present study was undertaken in an attempt to define more precisely the three dimensional arrangement of the proximal tubular cells in addition to the architecture of the adjoining basal lamina and peritubular capillaries.The kidney is prepared by fixing 2 x 4 mm pieces of tissue in 2% glutaraldehyde prior to treatment with 10 and 20% ethylene glycol in Ringer solution for 20 minutes each. The tissue is then frozen in liquid nitrogen. Other tissues are processed with 20, 40 and 60% glycerol in Ringers solution without prior fixation before freezing in liquid nitrogen. Tissues are placed in the McAlear and Kreutziger Freeze-Etching block and placed in a Varion VE-10 vacuum evaporator. Tissues are fractured after a temperature of -120°C is reached, and etched for periods ranging from several seconds through 15 minutes.
A New Multicolored Staining Procedure for One-Micron Sections of Epoxy Embedments
Authors: Ghidoni J. J. , Campbell M. M. , Adams J. G. , Thomas H. , Ramos E. E. 
Published: June 2020

Adequately stained one-micron sections of epoxy embedments offer a convenient means of selecting appropriate blocks for electron microscopic study. In most instances extensive light microscopic study of an experimental model is prerequisite to intelligent electron microscopic study of tissues from the model and these preparations are an aid in making the cytologic and histologic transitions from light microscopy to electron microscopy. This communication presents a staining procedure which evolved empirically in our laboratory and has enhanced the utility of the one-micron section. The procedure is now used routinely for staining one-micron sections of tissue embedded in a Maraglas-D.E.R. 732-DDSA mixture.The following procedure is carried out in Coplin jars set in 50°C water baths. More rapid staining can be obtained with more concentrated stain solutions used at higher temperatures; however, reproducibility is virtually lost.5 min. in 2% Periodic acid at room temperature.Rinse in water.5 min. in 0.15% Basic Fuchsin in 50% ETOH at 50°C.Rinse in water.5 min. in methylene blue-azure II at 50°C.Rinse in water and dry.Coverslip.
Correspondence of Etch Pits and Dislocations in Silicon
Authors: Anderson L. J. , Barrett C. R. , Taylor T. A. 
Published: June 2020

Etch pitting techniques have been extensively used to study both dislocation arrangements and densities in covalently bonded materials. In these investigations it is generally assumed that a one-to-one correspondence exists between etch pits and dislocations. In the course of the present work, which involved a study of dislocation arrangements in deformed silicon single crystals, it was observed that more than one dislocation can be associated with a single etch pit.Silicon single crystals, oriented for single slip, were deformed in compression at temperatures near 900°C. Typical dislocation arrangements are illustrated in Figures 1 and 2. Figure 1 is an optical micrograph showing the etch pit arrangement on the (211) face (the operative slip plane is normal to this face and the slip direction is parallel to this face). This sample was etched with the standard Sirtl etchant for 60 seconds. The etch pits are generally well defined and their density can be readily measured. Figure 2 is a transmission electron micrograph showing the arrangement of dislocations in the (111) slip plane. The dislocations often occur as elongated loops or dipoles and multipoles.
Charged Particle Irradiation of Thin Metal Films
Authors: Merkle K. L. 
Published: June 2020

Two of the main problems in the radiation damage in metals are the mechanisms of formation and the identification of defects that are produced due to the displacement of atoms from their regular lattice sites.We are concerned here with the class of those defects that can be observed by transmission electron microscopy of thin films. At present this includes those clusters of vacancies and interstitials that are larger than about 10Å in diameter and smaller than the film thickness (≈1000 Å).Thin expitaxially grown single-crystalline metal films have the advantage that the specimens can be observed before and after irradiation without being disturbed other than by the irradiation. Films of different orientations offer the possibility to study the anisotropy of the defects themselves as well as the anisotropies of the production of defects by a collimated beam of charged particles. Most important however is the use of thin films in the study of the energy dependence in irradiations with heavy charged particles in order to minimize the energy loss in the foil.
Development of High Resolution Electron Microscope, JEM-100B
Authors: Watanabe M. , Yanaka T. , Yamamoto M. , Suzuki S. , Nagahama Y. , Fujisawa U. 
Published: June 2020

The JEM-100B electron microscope has been developed with a view to the possibility of obtaining an ultimate resolving power at a beam accelerating voltage of 100kev. Prom the very nature of the instrument, the stability is fully ensured from a mechanical and electrical point of view. In the electron optical system, since highly excited lenses are utilized, image formation under the lowest aberration condition are ensured. The image forming system is of the 4-stage type which greatly expands the range of application not only in microscopic studies but also in the study of electron diffraction. Furthermore, with a view to simplifying instrument operation, various problems have been solved this enabling the instrument to be fully automated. The JEM-100B exhibits the following features.Objective Lens: At the present stage of development, fo=1.6mm. However, so as to be able to incorporate a lens (T. Yanaka et al, 1967) possessing an extremely small spherical aberration coefficient in the future, lens excitation has been made sufficiently high (8kA) and the movable aperture control knob and the specimen device have been designed accordingly.
A New Hot Stage for the Philips EM 200 and Its Calibration
Authors: Sprys J. W. , Gallagher P. C. J. 
Published: June 2020

A hot stage for use in metallurgical investigations with the electron microscope should have several, if not all, of the following characteristics.The specimen temperature should be measurable with accuracy over the full range of operation of the stage.The stage should allow a large tilt angle for diffraction and contrast work.The stage should not restrict expansion of the sample during temperature cycling thus avoiding alteration to the sample's defect structure from the presence of thermal stress.The heater and sample should approach equilibrium rapidly after any change in temperature, with a minimum of drift during the change, and a high degree of stability at temperature.The stage should permit study of as much of the thinned specimen area as is possible compatible with adequate thermal coupling to the furnace.
Preparation of Electron Transparent Metal-Matrix Composites
Authors: Pinnel M. R. , Lawley A. 
Published: June 2020

Numerous phenomenological descriptions of the mechanical behavior of composite materials have been developed. There is now an urgent need to study and interpret deformation behavior, load transfer, and strain distribution, in terms of micromechanisms at the atomic level. One approach is to characterize dislocation substructure resulting from specific test conditions by the various techniques of transmission electron microscopy. The present paper describes a technique for the preparation of electron transparent composites of aluminum-stainless steel, such that examination of the matrix-fiber (wire), or interfacial region is possible. Dislocation substructures are currently under examination following tensile, compressive, and creep loading. The technique complements and extends the one other study in this area by Hancock.The composite examined was hot-pressed (argon atmosphere) 99.99% aluminum reinforced with 15% volume fraction stainless steel wire (0.006″ dia.).Foils were prepared so that the stainless steel wires run longitudinally in the plane of the specimen i.e. the electron beam is perpendicular to the axes of the wires. The initial step involves cutting slices ∼0.040″ in thickness on a diamond slitting wheel.
Etched Sodium Chloride Surfaces
Authors: Rosauer E. A. , Lingscheit J. N. 
Published: June 2020

Treatment of a freshly-cleaved NaC1 surface with a solution containing 3 g HgCl2 per liter absolute ethanol results in typical inverted-pyramidal etch pits at the emergence points of dislocations. The pit sides are parallel to the [100] directions. There seems to be general agreement that crystal material at a dislocation emergence point has a higher dissolution rate than material at some distance from the emergence point. The role of the HgCl —the inhibitor—is not precisely understood; however, the literature suggests that the inhibitor is sorbed at certain sites near the emergence point and controls the rate of lateral and vertical dissolution. Since dissolution is the reverse of growth, removal of crystal material is thought to be on a monatomic scale.In this study freshly-cleaved NaCl surfaces were treated for various periods of time (1-30 sec) with ACS absolute methanol and with absolute methanol containing various concentrations of NH4Cl (1-20 g/1). Freshly-cleaved NaCl crystals were held with tweezers and swirled in the etchant for the designated time period.
An Electron Gun Scanning Microscope
Authors: Crewe A. V. , Johnson D. , Isaacson M. 
Published: June 2020

A simple scanning electron microscope has been built using a field emission electron gun. The gun is used alone, without the aid of auxiliary lenses, and is theoretically capable of producing a 100 Å probe with a beam current of 10-10 A. Such a beam current allows scan times of the order of a few seconds.A schematic drawing of the microscope is shown in Fig. 2. The field emission voltage is applied to the first anode which controls the emission current. An accelerating voltage is applied to the second anode, and the field between the anodes focuses the electrons to form an image of the tip at the specimen. The angular spread of the beam is limited by an aperture on the second anode.
Voltage Contrast in Scanning Electron Microscopy
Authors: Kimoto S. , Hashimoto H. , Mase K. 
Published: June 2020

In the study of such micro electronic devices as a transistor and an integrated circuit by using a scanning electron microscope the contrast of a secondary electron image reveals potential distribution on the surface of a specimen. The intensity of secondary electrons collected by a detector depends on the potential of the specimen surface because the yield of the secondary electrons is restricted by the surface potential and the trajectory of the secondary electrons from the specimen to the detector is disturbed by the field which is produced by the potential applied to the specimen. The relation between the contrast and the potential of the specimen surface varies according to instruments.A simple specimen was used in order to obtain the relation. Two copper blocks with flat surfaces were arranged with a narrow gap of about 50 μ. One of them is electrically grounded and the other is variously biased. The intensity of the secondary electrons emitted from each block of the specimen was measured at the output of a photomultiplier of the detector.
Precipitation in Al + 4% Cu Epitaxial Films
Authors: Herd S. , Mader S. M. 
Published: June 2020

Single crystal films in (001) orientation, about 1500 Å thick, were produced by R-F sputtering of Al + 4 wt % Cu onto cleaved KCl at 150°C substrate temperature. The as-deposited films contained numerous θ-CuAl2 particles (C16 structure) about 0.1μ in size. They were transferred onto Mo screens, solution treated and rapidly cooled (within about ½ min) so as to retain a homogeneous solid solution. Subsequently, the films were aged in vacuum at various temperatures in order to induce precipitation and to compare structures and morphologies of precipitate particles in Al-Cu films with those found in age hardened bulk material.Aging for 3 weeks at 60°C or 48 hrs at 100°C did not produce any detectable change in high resolution micrographs or diffraction patterns. In this range Guinier-Preston zones (GP) form in quenched bulk material. The absence of GP in the present experiments in this aging range is perhaps due to the cooling rate employed, which might be more equivalent to an aged and reverted bulk material than to a quenched one.
Morphology of Amorphous Polymers
Authors: Lambert S.L. , Yeh G.S.Y. 
Published: June 2020

Our general concept of the amorphous morphology of polymers is that of a structureless mass of coiled and intercoiled molecules. However, replica studies of freeze-fractured rubbers, amorphous polystyrene and polymethyl methacrylate and ion-etched glassy polycarbonate often suggest the presence of nodular structures (100-1000 Å) of unknown origin. Recently a nodular ball-like structure of the order of 100 Å was also observed in thin films of amorphous polyethylene terephthalate, its appearance being due to polymer molecules tending to back fold and arranging themselves more or less parallel to one another.We have extended these studies to several other polymers including amorphous and crystallizable polystyrene and polymethyl metha-crylate, trans- and cis-polyisoprene, polyphenylene oxide, etc. and have observed similar ball-like structures (Figs. 1 and 2). The size of these structures may vary from polymer to polymer (30-100 Å), however for a given polymer no substantial size variation has been observed with respect to preparation conditions, e.g., temperature, solvent and molecular weight.
Techniques to Study Devitrification in Glass Systems Using Electron Microscopy and Diffraction
Authors: Tufts Charles F. 
Published: June 2020

Adequate description of crystalline states in glass systems should include information about geometry, structure and perfection of crystals less than 1000Å in size. Such information can be obtained by analyzing thin sections (<2000Å thick) using transmission electron diffraction-contrast microscopy (TEDCM) and selected area electron diffraction (SAED). If surfaces can be prepared that represent bulk character, reflection electron diffraction (RED) should be employed as a supplementary tool. Preparation of thin glass sections and surfaces by chemical methods usually introduces serious artifacts. The techniques described here use surfaces produced by fracture in inert gas and are applicable to the study of various glasses and ceramics.The specimen is fractured in a dry box containing an inert gas such as nitrogen or argon with dew point lower than -50°C. The specimen is protected at all times by the gas when not under vacuum. After fracture, the specimen is moved to an electron diffraction camera filled with flowing inert gas until evacuated for analysis.
Electron Microscopy of Precious Opal
Authors: Amaral Eugene J. , Rau Robert C. 
Published: June 2020

Replica and transmission electron microscopy have been used to study the microstructure of precious opal. This mineral is an amorphous silica which is often prized as a gemstone because of its vivid display of iridescent colors when viewed in visible light. For the present study, specimens were examined in fractured, polished, and etched conditions.As shown in the figures, precious opal consists of many tiny silica spheres, of essentially uniform diameter, that have been deposited in an orderly array before silica cementation. Regularly spaced interstitial voids resulting from the ordered packing serve as a three dimensional diffraction grating for visible light, thus giving rise to the characteristic play of colors. The separation of the voids is controlled by sphere diameter, and determines the maximum wavelength of visible light diffracted. Thus specimens consisting of larger spheres diffract higher order colors (longer wavelengths) than specimens consisting of smaller spheres. For example, the specimen shown in Fig. 1 contained spheres of approximately 2700 Å diameter and diffracted all visible colors up through red, while the specimen shown in Fig. 2 contained spheres of approximately 2000 Å diameter and diffracted only blues and greens.
In vivo confocal imaging of the eye using tandem scanning confocal microscopy (TSCM)
Authors: Jester J. V. , Cavanagh H. D. , Lemp M. A. 
Published: June 2020

New developments in optical microscopy involving confocal imaging are now becoming available which dramatically increase resolution, contrast and depth of focus by optically sectioning through structures. The transparency of the anterior ocular structures, cornea and lens, make microscopic visualization and optical sectioning of the living intact eye an interesting possibility. Of the confocal microscopes available, the Tandem Scanning Reflected Light Microscope (referred to here as the Tandem Scanning Confocal Microscope), developed by Professors Petran and Hadravsky at Charles University in Pilzen, Czechoslovakia, permits real-time image acquisition and analysis facilitating in vivo studies of ocular structures.Currently, TSCM imaging is most successful for the cornea. The corneal epithelium, stroma, and endothelium have been studied in vivo and photographed in situ. Confocal scanning images of the superficial epithelium, similar to those obtained by scanning electron microscopy, show both light and dark surface epithelial cells.
Ruthenium red and alcian blue effects on outer structures of methanotrophic bacteria
Authors: Fassel T.A. , Schaller M.J. , Remsen C.C. 
Published: June 2020

Methane, a contributor to the “greenhouse effect”, is oxidized in the natural environment by methanotrophic bacteria. As part of a comprehensive research effort, we have been examining the ultrastructure of methanotrophs. These microorganisms have complex outer cell wall structures similar to those frequently found in other chemol itho- trophic bacteria. (1,2)In our work, we have focused on the “type” strains of Methylomonas albus BG8 and Methylosinus trichosporium OB3b. Between Spurr and LR White embedding resins, we found a difference 1n the preservation of an outer cup layer of BG8 external to the peripheral membranes. Cells from the same sample embedded in Spurr consistently lacked this feature (FIG. 1). This effect was overcome by an en bloc ruthenium red (RR) protocol that resulted in successful retention of the cup layer in Spurr resin (FIG. 2). For OB3b cells, the en bloc RR protocol resulted in an exterior bead feature distinguishable in thin section (FIG. 4) that previously was seen only by SEM.
The use of thick sections with transmission electron microscopy in combination with scanning electron microscopy to study the attachment of Neisseria gonorrhoeae to vero cells infected with Chlamydia trachomatis
Authors: Pontrefract R. D. , Ng C. W. , Ashton E. E. , Bergeron G. 
Published: June 2020

Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) are well known pathogens associated with sexually transmitted disease. Clinical studies have shown that these organisms are frequently found together, and it has been suggested that gonorrhoeae be used as a marker for chlamydial infections. The reason for the high rates of co-infection is not known. However, in vitro studies (Ng et al. manuscript in preparation) have shown that the adsorption of NG to Vero cells pre-infected with CT is increased at least twenty times compared with that obtained with non-infected cells. In order to determine the areas of attachment and the fine structure of the attachment sites of the gonococci to the CT infected Vero cells, both transmission electron microscopy (TEM) using thick (0.25-0.5μm) sections and scanning electron microscopy (SEM) were used.To prepare samples for TEM, Vero (African green monkey kidney) cells were grown in T-flasks for 48h in M199 + 10% fetal calf serum at 37C in an atmosphere containing 5% CO2.
GACH-prepared specimens for sem and confocal reflected light microscopy
Authors: Crang R. E. , Thompson B. 
Published: June 2020

Biological specimens prepared for SEM are difficult to observe in detail by means of light microscopy. Conventional epi-illuminescence produces relatively poor images with reflected light due to poor contrast and multiple scattering of the light (1). However, we have found that mammalian tissue culture cells prepared for SEM by means of the co-polymerized glutaraldehyde-carbohydrazide (GACH) technique (2), can be alternately observed by means of SEM and reflected light microscopy if the light optical instrument is a confocal tandem scanning microscope (TSM). The images produced with TSM show resolution comparable to that of the SEM at magnifications ≤ 1,000 X. Furthermore, due to the extremely small depth of focus containing high contrast and brightness, optical sections can be produced which bear detail similar to that in conventional TEM observations.Fibroblasts and myotobes, from newborn rat hindlimb muscles were grown in Eagle's minimum essential medium with 10% fetal calf serum on collagen- coated glass cover slips for a period of 7 d (3).
Analysis of the Mechanism of Microtubule Dynamic Instability Using a UV Microbeam to Sever Elongating Microtubules
Authors: Walker R.A , Inoue S. , Salmon E.D. 
Published: June 2020

Microtubules polymerized in vitro from tubulin purified free of microtubule-associated proteins exhibit dynamic instability (1,2,3). Free microtubule ends exist in persistent phases of elongation or rapid shortening with infrequent, but, abrupt transitions between these phases. The abrupt transition from elongation to rapid shortening is termed catastrophe and the abrupt transition from rapid shortening to elongation is termed rescue. A microtubule is an asymmetrical structure. The plus end grows faster than the minus end. The frequency of catastrophe of the plus end is somewhat greater than the minus end, while the frequency of rescue of the plus end in much lower than for the minus end (4).The mechanism of catastrophe is controversial, but for both the plus and minus microtubule ends, catastrophe is thought to be dependent on GTP hydrolysis. Microtubule elongation occurs by the association of tubulin-GTP subunits to the growing end. Sometime after incorporation into an elongating microtubule end, the GTP is hydrolyzed to GDP, yielding a core of tubulin-GDP capped by tubulin-GTP (“GTP-cap”).