bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron Microscopy of Liver in a Case of Neonatal Leukemia
Authors: Monroe J. H. , Chandra S. 
Published: June 2020

Histologic changes in the liver observed in cases of leukemia, particularly regarding the infiltration of leukocytes into the organ, have been recently reviewed. The present paper attempts to examine some of these changes on the fine-structural level.An autopsy sample of liver from a seven week old female infant with acute lymphoblastic leukemia was obtained six hours after death and immediately transferred into 2% glutaraldehyde in phosphate buffer. The tissue was processed for electron microscopy by standard procedures.A light microscope examination of the liver showed infiltration of lymphocytes in the portal radicles and the sinusoids. Parenchymal cells (P) adjoining the areas of extreme leukocytic infiltration (L) revealed the presence of dense granules which have not been previously described. A low power electron micrograph of such an area is shown in Fig. 1 where the disorganization of the parenchyma is clearly noticed.
High Ampere-Turn Density Coils for the Reduction of Magnetic Lens Size
Authors: Lund N.C. 
Published: June 2020

In Electron Microscope design it is often of considerable practical advantage to keep the amount of iron used in the column at the optically necessary minimum. To achieve this, lens dimensions must be kept relatively small with concomitant high ampere-turn density. In the design of the 500,000-volt column for the University of Virginia, ampere-turn densities in the order of 2500 to 3000 NI/in2 were made possible by the incorporation of high-efficiency cooling techniques in the coil design.A system was devised which would envelop the windings with a water-cooling jacket of minimum thickness in such a manner as to serve also as the sole structure or support for the windings. The combining of cooling and support functions into a single thin-walled structure allows maximum window area to be utilized for windings, within the confines of established iron circuitry dimensions.
A 1 mev Electron Microscope Facility
Authors: Fisher R. M. , Lally J. S. 
Published: June 2020

The resolution and transmissive power of the transmission electron microscope improve markedly with increasing accelerating voltage. In order to realize the advantages of high voltage microscopy in U. S. Steel's metallurgical research program, the Board of Directors, in December 1965, approved the construction of a 1 mev electron microscope at the Fundamental Research Laboratory. All three phases of the microscope facility, i.e. 1 mev accelerator, electron optical column and special building, have progressed rapidly since that time and the present projection is that the instrument will go into operation in early summer of 1967.The microscospe uses an open Cockcroft-Walton accelerator manufactured by Haefely Ltd. as the electron source and scaled-up conventional magnetic lenses in the optics. The column, manufactured by RCA, has a number of unique features including a 6th lens used as a projector to enlarge a selected area diffraction pattern and to give a wider range of magnifications at the highest voltages.
Application of the Election Microscope to the Study of Polytetrafluoroethylene
Razor-Blade Coatings
Authors: Symons N. K. J. 
Published: June 2020

Applying a polytetrafluoroethylene (PTFE) coating to the edges of razor blades leads to a marked increase in shaving comfort, due to a reduction in the flank frictional adhesion forces encountered by the blade and consequent decreased drag on the beard hairs during cutting. The electron microscope has provided valuable information concerning the nature of this blade coating and its behaviour during the shaving process.In the coating operation, the blade edges are sprayed with an aqueous dispersion of PTFE, and the blades then heated to about 400 C. to melt the dispersion polymer particles, which coalesce to form a coherent coating; the ability to withstand this temperature without undue loss of mechanical properties is one of the advantages of the stainless steel blades used. Replication shows the coating to consist of very small crystals in apparently random orientation.
Substrate-Overgrowth Interaction During the Epitaxial Growth of Niobium on Magnesium Oxide
Authors: Olsen K. H. , Hutchinson T. E. 
Published: June 2020

Epitaxial growth studies of niobium on cleaved magnesium oxide have shown that chemical interaction between substrate and condensate is a controlling parameter in the resultant film structure. High purity niobium (99.93%) was vacuum vapor deposited by electron beam melting onto heated single crystals of magnesium oxide. The resultant film structures were examined by transmission electron microscopy and electron diffraction.Examination of films grown under the conditions indicated in Fig. 1 has yielded the following generalized conclusions: a) all composite films contain an initial fcc layer (<100 Å) having a lattice parameter of 4.38 At 0.02 and an orientation and direction of (001)fcc//(001)MgO and [010]fcc// [010]MgO respectively.
Lorentz Miscroscopy of Thick Ni-Fe Films
Authors: Lo D. S. , Olson A. L. , Simon W. J. , Torok E. J. 
Published: June 2020

The importance of Lorentz microscopy in carrying out investigations of the magnetic microstructure of Ni-Fe films is attested to by the extensive amount of literature on the subject. As the electron beam passes through the magnetic film, it is acted upon by the Lorentz force, , where e and are the electron charge and velocity and is the local magnetization component perpendicular to the electron beam. Most Lorentz microscopy has been reported for films less than 1200 Å thick. In this paper, techniques are reported which have made Lorentz microscopy possible in films 2000 Å thick. Some of the interesting results are also briefly reported.The work reported herein was done with an Hitachi HU 10 at the maximum available potential of 100 KV. Modifications in the stage were made so that the sample films could be placed from 15 to 35 mm above the objective lens. With the sample in this position, the objective lens current necessary for focus was 26 ma instead of the usual 135 ma. In an effort to increase the beam current, the filament was adjusted so that the tip of the filament was placed even with the bottom of the grid cap hole.
Clean Electron Microscope Substrate Films Used for Micrometeorite Collection and Study
Authors: Davies D. M. , Kemner R. , Fullam E. F. 
Published: June 2020

All serious electron microscopists at one time or another have been concerned with the cleanliness and freedom from artifacts of thin film specimen support substrates. This is particularly important where there are relatively few particles of a sample to be found for study, as in the case of micrometeorite collections. For the deposition of such celestial garbage through the use of balloons, rockets, and aircraft, the thin film substrates must have not only all the attributes necessary for use in the electron microscope, but also be able to withstand rather wide temperature variations at high altitude, vibration and shock inherent in the collection vehicle's operation and occasionally an unscheduled violent landing.Nitrocellulose has been selected as a film forming material that meets these requirements yet lends itself to a relatively simple clean-up procedure to remove particulate contaminants. A 1% nitrocellulose solution is prepared by dissolving “Parlodion” in redistilled amyl acetate from which all moisture has been removed.
Scanning Microscopy of Thin Biological Specimens
Authors: Crewe A. V. , Wall J. 
Published: June 2020

We have recently improved our scanning electron microscope to a level that point resolution of 5 Å or so is possible. The electron current in the focused spot is about 10-10amps so that good pictures can be obtained with a 10 sec exposure and the highest quality pictures can be obtained in 100 sec.The resolving power of this microscope is now comparable to that in a conventional transmission microscope for thin biological specimens and it is therefore of value to compare micrographs taken on the two types of instrument.
A Scanning Electron Microscope from Hitachi
Authors: Onuma Yoshirou , Hujiyasu Tatsuo , Kakinuma Yukio 
Published: June 2020

Hitachi, Limited has recently completed the development of a commercial scanning electron microscope, the features of which are discussed herein. Fig. 1 is an external view of the instrument.Lens SystemA three-stage reduction lens system is employed to obtain a short electron beam path. This minimizes the effects of any external electromagnetic or stray electrical fields as well as mechanical vibration or shock. Axial alignment is easily accomplished by transverse adjustment of the electron gun and lens system. Aperture plates with different hole sizes are provided in the condenser lens, deflection coil, and on the principal plane of the objective lens. The apertures are easily removed for cleaning. The electromagnetic stigmator is located outside the objective lens to facilitate removal for cleaning. Resolution of 200Å~250Å is guaranteed.
Recent Results from the 500-KV Virginia High Voltage Electron Microscope
Authors: Lawless Kenneth R. , Geiss Roy H. 
Published: June 2020

The installation of the RCA 500-kV electron microscope in the Department of Materials Science at the University of Virginia was completed during the summer of 1968. An overall view of the microscope is shown in Fig. 1. The microscope was designed for operation by a single operator in a manner as similar as possible to that of the conventional 100-kV microscope.The microscope contains a number of unique features. The high voltage is provided by an insulated core transformer and is fed to the accelerator on top the microscope column by an overhead cable. Voltages from 100 to 500-kV in 10-kV steps are available. The vacuum system consists of a combination of a high speed diffusion pump for initial pumpdown, and three ion pumps for normal operation Of the microscope.
Electron Optical Micro Recording at Tübingen
Authors: Möllenstedt Gottfried , Speldel Rumold , Schief Rudolf , Koops Hans , Holl Peter 
Published: June 2020

Some progress in the electron-optical recording of micro structures has been made using the following three principles:1) A micro structure is recorded by a fine electron probe of constant current magnetically deflected according to the desired pattern.2) The probe scans the recording plane with constant velocity and line distance while its intensity is controlled by the signal from a vidicon pick-up tube.3) A stencil is electron-optically demagnified using a wide stationary beam.The recording mechanisms area) Decomposition of a collodion foil.b) Chemical changes in photoresist materials.c) Surface contamination by polymerides on carbon, beryllium, silver, and other substrates.
Stereography of Freeze Etched Replicas
Authors: McAlear James H. , Shatos Marie , Demsey Anthony , Donovan Anita 
Published: June 2020

The frequent analogy made between the appearance of freeze etch replicas and the lunar landscape is appropriate in the sense that both are best viewed as if they were opaque irregular surfaces illuminated from behind and to the side of the observer. Replicas are actually illuminated by a transmitted electron beam and the illusion of a lighted opaque surface arises from the heavy metal shadow which appears light when viewed as a negative.Stereography adds to the perspective provided by shadowing and reveals remarkable differences in elevation which would be unnoticed in single micrographs. This technique now seems essential to the proper interpretation of freeze etched replicas. It further aids in the detection of artifacts due to the electron density of the replica itself.
Electron Holography and the Correction of Spherical Aberration
Authors: Crewe A. V. , Saxon J. 
Published: June 2020

Division of wavefront electron holograms have been recorded using a field emission source and electrostatic biprism to get an off axis reference beam. A schematic diagram of the apparatus used is shown in Fig. 1. The electron beam is focused to a point above the specimen and biprism fiber by a specially designed electron gun. With positive potential applied to the fiber the Fresnel diffraction pattern of the specimen is superimposed on the interference pattern of the two effective sources forming the hologram. Two standard magnetic projector lenses are used to magnify the hologram which is recorded outside the vacuum system directly on film in contact with a phosphor-coated fiber optic faceplate. A He-Ne laser is used for the reconstruction as shown in Fig. 2. Following Meier's analysis it is found that when a parallel beam is used to reconstruct the wavefront, the real image will be in focus a distancein front of the hologram where m is the total magnification of the hologram and μ is the ratio of the illuminating to recording wavelengths.
Displacement Rate Effects in Heavy Ion Bombardment of Stainless Steel
Authors: Laidler J. J. 
Published: June 2020

The effectiveness of heavy ion bombardment as a technique for the simulation of high fluence fast neutron irradiation effects depends on the significance of the widely differing displacement rates prevailing with the two types of bombarding particles. Previous experiments have established the qualitative equivalence of microstructures in neutron-irradiated and ion-bombarded stainless steel, but most current theories of defect nucleation and growth in irradiated metals are explicitly rate-dependent. Hence, the present work was performed to determine in a quantitative manner any effects ascribable to a difference in atom displacement rate.Type 316 stainless steel specimens were bombarded at 425°C with 5 MeV Ni++ ions, using the Ion Physics Corporation tandem Van de Graaff accelerator.
The Structure of Radiation Cross-Linked Poly (ethylene oxide) Gels
Authors: Cluthe C. E. , Cocks G. G. 
Published: June 2020

Aqueous solutions of a 1 weight-per cent poly (ethylene oxide) (PEO) were degassed under vacuum, transferred to a parallel plate viscometer under a nitrogen gas blanket, and exposed to Co60 gamma radiation. The Co60 source was rated at 4000 curies, and the dose ratewas 3.8x105 rads/hr. The poly (ethylene oxide) employed in the irradiations had an initial viscosity average molecular weight of 2.1 x 106.The solutions were gelled by a free radical reaction with dosages ranging from 5x104 rads to 4.8x106 rads.
A Technique for Displaying Theoretical Transmission Electron Microscope Images
Authors: Fillingham P. J. , Leamy H. J. , Maher D. M. 
Published: June 2020

Since the earliest work on computer simulation of electron microscope images, it has been realized that a technique for producing a high quality image would facilitate analysis of the information content of theoretical intensity data. In particular, this would be an aid in image analysis and testing approximations used in electron diffraction theory.A technique has been developed for producing a semiglossy print from data on magnetic tape using a commercial facsimile device. In the present application only the receiver of the facsimile device is used to produce a simulated electron micrograph. An array of intensities corresponding to the light or dark field image of a defect is computed. A simple two-dimensional interpolation scheme gives an enlarged array (on magnetic tape) which is then converted to analog form and transmitted to the receiver of the facsimile device.
Microdensitometers and Data Processing for Electron Microscopy
Authors: Bender Robert , Rowe James E. 
Published: June 2020

Most of the information obtainable from transmission electron microscopy is lost in the course of normal ‘print and look’ handling -or at least made difficult to retrieve. Not only is there an actual degradation of information, but operations such as the measurement of areas etc. are then carried out manually at great cost in time, and loss of accuracy. One of the main causes of loss of accuracy is the understandable reluctance of competent persons to do a great deal of highly repetitive work. Unfortunately in order to get good error bounds in most cases of interest multiple measurements must be made. Data processing technology is now sufficiently developed to make automatic picture processing an attractive and realizable goal. While this is not specifically a paper on image processing, some simple and possibly generally useful algorithms will be presented.The first step in any data processing schema is data acquisition. In the case of transmission electron microscopy several methods are available, some with advantages in unique situations.
On the Rate Controlling Mechanism Operative During Superplastic Flow
Authors: Gecklini E. , Anderson L. J. , Barrett C. R. 
Published: June 2020

This investigation is concerned with a determination of the rate controlling mechanisms operative during superplastic flow. The experimental technique involves the deformation of Pb-Sn eutectic samples in a scanning electron microscope. Surface observations of grain shape changes and grain boundary shearing are used to assess the importance of the various deformation mechanisms. As described below, the experimental observations are consistent with a model of grain boundary sliding in association with localized deformation near grain boundaries to maintain coherency.Experiments are carried out using a specially designed tensile stage in an AMR 900 microscope. The gage section of the tensile sample is 3 mm long, 2 mm wide and 0.5 mm thick. The grain size range investigated is 2 - 5μ and deformation is carried out at room temperature. The tensile stage is designed such that the ends of the sample are translated in opposite directions.
Studies of Fracture in the High Voltage Electron Microscope
Authors: Bauer R. , Geiss R. H. , Lyles R. L. , Wilsdorf H. G. F. 
Published: June 2020

Experimental techniques for the study of in-situ crack propagation and fracture have been developed for use in the 500 kV electron microscope at the University of Virginia. The investigations are concerned with the problems of defining the mechanism of crack propagation on a microstructural scale and the relationship of thin film vs bulk behavior. By restricting ourselves to ductile fracture, the features to be seen if bulk behavior dominates are necking, shear, and hole formation in front of the propagating cracks.In-situ straining of the specimens was accomplished using a hydraulically loaded tensile stage designed and built for use with one of the radial access ports provided in the microscope.Two types of specimens have been investigated: (i) single crystal ribbons of silver grown from solution using an ionic reduction technique and (ii) annealed polycrystalline sheet stainless steel. The former served primarily for studying the fundamental aspects of ductile fracture while with the latter the influence of grains and grain boundaries on fracture was investigated.
Disappearance Voltage Determinations Using a Convergent Beam
Authors: Bell W. L. 
Published: June 2020

Disappearance voltages for second order reflections can be determined experimentally in a variety of ways. The more subjective methods, such as Kikuchi line disappearance and bend contour imaging, involve comparing a series of diffraction patterns or micrographs taken at intervals throughout the disappearance range and selecting that voltage which gives the strongest disappearance effect. The estimated accuracies of these methods are both to within 10 kV, or about 2-4%, of the true disappearance voltage, which is quite sufficient for using these voltages in further calculations. However, it is the necessity of determining this information by comparisons of exposed plates rather than while operating the microscope that detracts from the immediate usefulness of these methods if there is reason to perform experiments at an unknown disappearance voltage.The convergent beam technique for determining the disappearance voltage has been found to be a highly objective method when it is applicable, i.e. when reasonable crystal perfection exists and an area of uniform thickness can be found. The criterion for determining this voltage is that the central maximum disappear from the rocking curve for the second order spot.
Thin Pyrolytic Graphite Films for Electron Microscope Substrates
Authors: Riddle George H. N. , Siegel Benjamin M. 
Published: June 2020

A routine procedure for growing very thin graphite substrate films has been developed. The films are grown pyrolytically in an ultra-high vacuum chamber by exposing (111) epitaxial nickel films to carbon monoxide gas. The nickel serves as a catalyst for the disproportionation of CO through the reaction 2C0 → C + CO2. The nickel catalyst is prepared by evaporation onto artificial mica at 400°C and annealing for 1/2 hour at 600°C in vacuum. Exposure of the annealed nickel to 1 torr CO for 3 hours at 500°C results in the growth of very thin continuous graphite films. The graphite is stripped from its nickel substrate in acid and mounted on holey formvar support films for use as specimen substrates.The graphite films, self-supporting over formvar holes up to five microns in diameter, have been studied by bright and dark field electron microscopy, by electron diffraction, and have been shadowed to reveal their topography and thickness. The films consist of individual crystallites typically a micron across with their basal planes parallel to the surface but oriented in different, apparently random directions about the normal to the basal plane.
Nerve Cells and Fibers in the Optic Lobe Cortex of Octopus
Authors: Case Norman M. , Gray E. G. 
Published: June 2020

Montages of electron micrographs from the outer portion of the cortex of the optic lobe of Octopus are shown. Sheets of dark cytoplasm which originate from glial cells in the outer granular layer form a basement layer separating the outer granular layer from the deeper plexiform layer.Optic nerve fibers from the retina entering the optic lobe around its periphery must pass between the amacrine cells composing the bulk of the outer granular layer. Here they are the darker of the two fiber types that can be identified. Passing through the basement layer they expand into large “carrot” shaped terminal endings easily identified by their dark appearance caused by the extremely high content of synaptic vesicles they contain.Fibers in the neuropil press tightly against and indent the “carrots” and occasionally make synaptic contact with them. Some fibers penetrate deeply into the “carrots” where they branch and terminate in grape-like clusters that show many synaptic contacts with the enveloping bag.
Ultrastructure of the Actinomycele Ceodermatophilus Obscurus
Authors: da Fonseca A. Freitas , Edwards M. R. 
Published: June 2020

Geodermatophilus, a new generic taxon of the Dermatophylaceae (Actinomycetales), was first described by Luedemann and shown to display close similarities to Dermatophilus congolensis, previously described in our laboratory.Although Geodermatophilus has been studied by electron microscopy, the present investigation was undertaken to clarify further some ultrastructural aspects of this organism in relation to those of D. congolensis. Standard procedures for chemical fixation, as well as recently developed methods for physical fixation, were chosen but the present report is concerned only with results of thin sections. Cells from 16 hr. to 15-day-old cultures, in the medium described by Luedemann, were fixed with cacodylate buffered glutaraldehyde followed by osmium tetroxide in veronal acetate buffer, or according to Kellenberger et al. Dehydration was in ethanol and embedding in Epon 812.