bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation and Structural Studies of “A” Particles from Leydig Cell Tumors
Authors: Sarkar Nurul H. , Kramarsky Bernhard , Moore Dan H.
Published: June 2020

The presence of large inclusions of intracytoplasmic A particles (Fig. 1) in Leydig cell tumors has been described (1,2). These A particles were extracted from minced tumors by homogenizing them twice in 5 volumes of SET buffer (0.2M sucrose, 0.001M EDTA and 0.01M Tris HCl, pH 7.2). The extract was clarified by low speed centrifugation and treated with one tenth volume of 5% Triton X-100 in SET followed by one tenth volume of 1M NaCl. The resulting mixture was again clarified by low speed centrifugation and the supernatant was treated with DNAse following high speed centrifugation. The pellet was resuspended in SET, layered over a preformed CsCl density gradient and centrifuged in a Spinco SW 39 rotor.
Effect of Acetone and Kerosene on Skin Ultrastructure
Authors: Lupulescu A. P. , Pinkus H. , Birmingham D. J.
Published: June 2020

Our laboratory is engaged in the study of the effect of different chemical agents on human skin, using electron microscopy. Previous investigations revealed that topical use of a strong alkali (NaOH 1N) or acid (HCl 1N), induces ultrastructural changes in the upper layers of human epidermis. In the current experiments, acetone and kerosene, which are primarily lipid solvents, were topically used on the volar surface of the forearm of Caucasian and Negro volunteers. Skin specimens were bioptically removed after 90 min. exposure and 72. hours later, fixed in 3% buffered glutaraldehyde, postfixed in 1% phosphate osmium tetroxide, then flat embedded in Epon.
Lining Acid Mucopolysaccharides in Aortic Atherosclerosis
Authors: Gore Ira , Sekhri Karta K.
Published: June 2020

Ruthenium red (RR), an inorganic dye, has been shown to have a special affinity for acid mucopolysaccharides (AMPS). As used in combination with osmic acid in fixation, surface deposits of these substances are densely stained and readily visualized in the electron microscope. To localize AMPS at the electron microscope level, several female New Zealand albino rabbits were fed ad libitum a commercial diet supplemented with 3.2% corn oil and 0.8% cholesterol for 4 and 8 weeks. The control group was maintained on commercial diet only. In order to grossly visualize aortic lesions, rabbits were administered 5 to 8 ml. of Evans Blue via ear vein, one hour prior to sacrificing by Nembutal. After opening the thoracic cavity, a perfusion, mixture containing gluteraldehyde and paraformaldehyde was injected through the left ventricle.
A Simplified Placenta-Like Brooding System in Bulgula neritina (Bryozoa)
Authors: Woollacott Robert M. , Zimmer Russel L.
Published: June 2020

Embryos of many bryozoans are retained during development within a helmetshaped brood chamber that is composed of two parts: an outer, double-walled, calcified ooecial fold and an inner, membranous ooecial vesicle. The embryo is brooded “externally” between these two structures and, in Bugula neritina, increases 27 to 35 fold in volume during its embryogenesis. Since the blastocoelic space is obliterated early in development, this change represents an increase in tissue mass. Clearly, some form of extra-embryonic nutrition is implicated. Calvet first noted that the lining of the ooecial vesicle in regions adjacent to the embryo undergoes a pronounced hypertrophy, and Marcus later proposed that this epithelium provides nutrition to the young. Sileh, however, suggested that the hypertrophied layer functions only as a supportive cushion.
The Fine Structure of Calcoblasts in the Regenerating Sea Urchin Spine
Authors: Heatfield Barry M. , Travis Dorothy F.
Published: June 2020

The endoskeleton of echinoderms is composed of fenestrated calcium carbonate (calcite) permeated by interconnecting channels filled with a variety of cell-types and extracellular fluid containing collagen fibrils. To identify and characterize skeletogenic cells and explore the mechanism of skeleton growth in echinoderms, tissues of regenerating spines of the sea urchin Strongylocentrotus purpuratus were examined by electron microscopy.

The tip of the young regenerate is composed of two layers of tissue: an outer epidermis and an inner calcified dermis separated by a thin basal lamina (Fig. 1). In the apical dermis the skeleton consists of longitudinally oriented microspines interconnected by horizontal calcite bridges. During preparation of thin sections, skeletal mineral was lost, leaving a hole, indicated by (ms) in Figs. 1, 2, and 4.
Cuticular Pores in a Marine Mite
Authors: Crowe John H.
Published: June 2020

Several species of marine mites are known to possess elaborate cuticular pores, the function of which is not known (Newell, 1947). In the present investigation the fine structure of the cuticular pores in a Halacarid mite, Copidognathus curtusi was studied, with a view towards discovering the function of the pores.

For scanning electron microscopy the animals were fixed in cacodylatebuffered glutaraldehyde, post-fixed in osmium, and freeze-dried. For transmission electron microscopy they were fixed as above, embedded in Spurr's low viscosity epoxy resin, and sectioned on diamond knives.

C. curtusi was chosen for study because of the abundance of pores in its cuticle.
Visualizing the Structure of Macromolecules and Cell Structures in the Natural State
Authors: Parsons D.F.
Published: June 2020

A main objective of biological electron microscopy is the visualization of the internal structure of macromolecules and such structures as membranes, ribosomes etc. With respect to individual molecules it is hoped to see confirmation of the peptide chain in proteins and the chain of bases in nucleic acids. A more optimistic objective is that the individual amino acids and purine or pyrimidine bases will be recognizable from their shape. If achieved, these objectives should greatly speed up progress in the study of biological structure and function especially for materials where biochemical analysis and sequencing is very time consuming and x-ray crystallography not practical. A major effort to develop the electron microscope to this capability should be amply repaid by the structural advances made.
Methods for Viewing by Scanning Electron Microscopy the Interior Organization of Protoplasts of Plant Cells
Authors: Humphreys Walter J. , Wodzicki Tomasz J.
Published: June 2020

The three-dimensional organization of protoplasts of plant cells may be studied by scanning electron microscopy by exposing the cell interiors by freeze-fracturing followed by freeze-drying. Tissue blocks (1 mm3) are double fixed in glutaraldehyde and osmic acid, washed in several changes of distilled water, and positioned in shallow wells drilled into the centers of specimen stubs used for scanning electron microscopy (Kent Cambridge type). Each specimen is frozen into place with a small droplet of water by plunging the specimen holder into liquid nitrogen. While under liquid nitrogen 0. 1-0. 2 mm of tissue left projecting out of the well is cut off level with the specimen holder surface by a single thrust of a pre-cooled razor blade.
Structure of Ribosomes of Rat Liver Cells
Authors: Unuma T. , Senda R.
Published: June 2020

To compare the substructure of the isolated ribosomes with that in situ of the cytoplasmic ribosomes and the fibrillar and granular components of nucleoli, the sections of the liver cells of normal and actinomycin D-treated Wistar rats were observed in electron microscope. Tissues of the liver were fixed in osmium tetroxide and formalin, or in osmium tetroxide alone, embedded in Epon-Araldite or in Epon, sectioned and observed with a JEM 100 electron microscope after being stained with uranyl acetate and lead citrate. For RNase or DNase treatment, the tissues were fixed in formalin for 15 min and treated with the enzymes.
Uultrastructure of Microtubules
Authors: Nagayama Ariaki
Published: June 2020

Vinblastine(Vb) or vincristine, alkaloid derived from Vinca rosea is known for its antimitotic activity by regrouping of microtubules into paracrystalline form within the cells. A rapid purification method of vinblastine-induced microtubular paracrystals(PC) has provided us with a fresh and pure microtubular material demonstrating the presence of a labile ATPase associated with the PC. The present report is concerned with the fine structure of purified microtubules of mammalian cultured cells.

Confluent monolayer cultures of L cells were incubated for 20hrs with 10-5 M Vb (donated from Shionogi Seiyaku & Co., Osaka, Japan).
Surface Charge on Human Colinic Epithelial Cells as Shown by Ferritin Labelling
Authors: Mukherjee T. M.
Published: June 2020

Recent observations suggest the glycoprotein surface coat of the intestinal epithelial cells to be involved in the metabolic activities of the absorptive cells. In fact such considerations led Crane to speculate and include the “glycocalyx” as an essential component of the “digestive absorptive surface”. In spite of such speculations no conclusive evidence in support of this contention has yet been obtained. One such speculation has been that the surface coat because of its high negative charge is responsible for the adsorption of materials prior to their terminal breakdown and absorption. To test this hypothesis a study was undertaken to reveal the charge distribution over the luminal surface, of the brush border plasma membrane, i.e. the region of the “glycocalyx”.
The Morphology of Normal and Abberrant Murine Type Leukemia Virus and Its Relationship to Ribosomes
Authors: Tahmisian T. N. , Ainsworth E. J.
Published: June 2020

Studies are in progress to characterize a transmissible leukemia and the causal agent which is presumably viral. The neoplasm, originally isolated from an aged irradiated B6CF1, mouse, has been transmitted in irradiated (200 R; 250 kVp X rays) weanling mice by intraperitoneal injection of millipore filtered (0.45μ) supernatant from spleen cell suspensions. At 22 days after filtrate injection in syngeneic mice, spleen, lymph nodes, and thymus were removed and prepared for electron microscopy to determine the presence of virus and morphology of viral development.

The ultrastructure of cells from the above organs showed viral infection by a murine type leukemia virus with many “C” type buds 90 to 110nm formed in the cisternae of the rough endoplasmic reticulum (Fig. 1). The limiting membrane of the “C” type virus, apparently isolating it from the cytoplasm, is the unit membrane from the rough endoplasmic reticulum. The viral membrane is not invariably intact.
Freeze-Etch Replicas of the Mouse Proximal Tubule Cell
Authors: Spurlock Ben O.
Published: June 2020

The fine structure of the mouse kidney has been studied in detail. Attempts at preserving this metabolically highly sensitive organ in the “closest to living state” have prompted some rather elaborate and involved methods of specimen preparation. Acknowledging that these techniques probably represent the best methods of preserving the integrity of this organ, it was felt that freeze-etch techniques might provide insight into structures heretofore unappreciated by conventional electron microscopy of thin sectioned material. The present report deals with the fine structure of the mouse renal proximal tubules as visualized in replicas of freeze-fractured and freeze-etched preparations.

The left kidneys of lightly anesthesized mice were surgically exposed and fixed with 2% glutaraldehyde/0.1M phosphate buffer (pH 7. 2) by either the drip method (2) or by vascular perfusion (3). The kidneys were removed and stored in 0.1M phosphate buffer with 5% sucrose.
Relation Between the Function and the Ultrastructure of Profusely Appearing Microbodies in Hydrocarbon-Utiliizable Yeasts
Authors: Osumi M. , Fukui S.
Published: June 2020

Many reports have been published on physiological activity and metabolism of hydrocarbon-utilizable fungi, but only a few results were reported on their ultrastructures. We found a number of microbodies in a cell of Candida grown in n-paraffin by electron microscopical observations. As similar microbodies in plant cells have been identified as the peroxisome, we studied catalase activity of Candida cells grown with hydrocarbon, and considered its relation to the microbody. We believe that this is the first report on the biogenesis of microbodies in yeasts, and is important in relation to the mitochondriogenesis.

Seven strains of Candida were used in this study. Each strain was grown with n-paraffin mixture (C10-C12), inorganic salt medium at 30°C under shaking of 220 r.p.m. Respiratory activity, cytochrome synthesis, and catalase activity were measured. The localization of catalase was further examined by cytochemical methods with DAB (3.3'-diaminobenzidine). For electron microscopical observations, cells were fixed with glutaraldehyde-OsO4, or glutaraldehyde-KMnO4.
A Possible Origin of Myeloid Bodies in Oxygen Exposed Tissues
Authors: Takahashi Akira , Philpott Delbert E.
Published: June 2020

Myelin-like figures or myeloid bodies occur in many tissues, especially after injury and with increasing age. The breathing of 100% oxygen also produces myeloid bodies.

Tissues from rats exposed to 100% oxygen at one atmosphere for 72 hours were examined in the electron microscope. Samples from the brain, lung, spleen, heart and skeletal muscle, kidney and small intestine were fixed in glutaraldehyde, followed by osmium. Thin sections were stained in uranyl acetate and lead. Small myeloid figures which appeared as membrane pools, some showing Lamellae with about 45 Å spacing, were found in all the tissues examined. These figures were also found in the mitochondria and often gave the appearance of originating at this site (Figs. 1, 2, 3, 4). Invagination of membrane pooling occurs in places along the mitochondria. The various sizes of these membrane pools and possible extrusion and breakdown of the mitochondria suggests the mitochondria as a source of the myeloid bodies present after tissue damage from oxygen exposure.
High Spatial Resolution Auger Electron Spectroscopy
Authors: MacDonald Noel C.
Published: June 2020

During the past several years, Auger electron spectroscopy (AES) has developed from a research curiosity to a practical surface chemical analysis technique. The practical applications of AES have been further increased by combining AES with simultaneous ion sputter etching; this powerful combination of AES and sputter etching is now routinely used to chemical profile thin film and other composite structures with a depth resolution of 10 - 50 Å. AES is sensitive to all elements except hydrogen and helium, and spectra for the majority of the elements are now cataloged in one reference source.

AES is performed by electron bombarding a solid surface and energy analyzing the resulting secondary electrons. The secondary electrons that have undergone Auger transitions produce small peaks in the secondary electron distribution function, and the positions of these peaks in energy are used to identify the elements producing the transitions.
Description of a New High Resolution Scanning Transmission EM
Authors: Beer Michael , Wiggins J. W. , Woodruff David , Zubin Jon
Published: June 2020

A high resolution scanning transmission electron microscope of the type developed by A. V. Crewe is under construction in this laboratory. The basic design is completed and construction is under way with completion expected by the end of this year.

The optical column of the microscope will consist of a field emission electron source, an accelerating lens, condenser lens, objective lens, diffraction lens, an energy dispersive spectrometer, and three electron detectors. For any accelerating voltage the condenser lens function to provide a parallel beam at the entrance of the objective lens. The diffraction lens is weak and its current will be controlled by the objective lens current to give an electron diffraction pattern size which is independent of small changes in the objective lens current made to achieve focus at the specimen. The objective lens demagnifies the image of the field emission source so that its Gaussian size is small compared to the aberration limit.
A 700°C Hot Stage for the JEOL JSM-2 Scanning Electron Microscope
Authors: Maurin J. K.
Published: June 2020

A heating device compatible with the standard JSM-2 goniometer stage has been developed, thereby providing rapid interchangeability between normal and hot stage microscopy. The hot stage is designed for temperatures ranging from 25 to 700°C and requires only minor modification to and interference with normal microscope functions. The heating carriage is inserted or removed through the airlock like a normal specimen holder; power and thermocouple leads are connected through the standard instrument patch board, and the main structural components consist of stainless steel, copper, nickel and sapphire. Other important internal components of this system include a large cryogenic surface above the specimen carriage and a water chilled base plate which replaces the normal solid dovetail plate. Externally, a direct current power source and a recorder to monitor temperature are required.

Fig. 1 shows the arrangement of the heating device and electrical contacts. The hot stage consists of a carriage with the normal dovetail runners which supports the heating device, thermal shielding structure, and electrical connections.
A Novel Diode Detector in a Scanning Transmission Microscope
Authors: Kim C. S. , Everhart T. E.
Published: June 2020

High-resolution in a scanning transmission electron microscope can be obtained using a condenser-objective lens. A suitable semiconductor diode is an efficient detector of high-energy electrons; an annular detector allows unscattered primary electrons or inelastically scattered electrons to pass through the hole, while elastically scattered electrons strike the diode, and are detected.

Electrons passing through a thin sample may be elastically scattered through angles of many tens of milliradians, inelastically scattered with angular deflections of ∼ 1 mr, or not scattered at all. The inelastically scattered electrons do not depart significantly from the unscattered beam. Since the beam convergence angle at the sample is typically a few milliradians, the elastically scattered electrons can be collected using a detector with a hole positioned at the beam axis to allow the inelastically scattered electrons and the unscattered electrons to pass through. These electrons can be separated with an electron spectrometer to provide important contrast effects.
TEM of Conducting Filament in Nb-Nb2O5-Bi Switching Glass Structure
Authors: Anderson Ronald M.
Published: June 2020

There has been considerable interest in the electronic component industry concerning the switching phenomena exhibited by certain glasses. Switching is observed in thin Nb2O5 glass sandwiched between Niobium and Bismuth conductors. A typical device vertical structure is shown in Fig. 1. Transmission electron microscopic techniques were used to consider structural aspects of the Nb-Nb2O5-Bi devices. First, the microstructure of the conducting filament was unknown and secondly, optical and scanning electron microscopy showed the top of the one micron wide filament to be shaped like a volcano and situated in the center of a large six to ten micron wide crater in the Bi top conductor with no apparent metallic contact to the Bi. This last point is illustrated in the optical micrograph, Fig. 2a, and the SEM photo, Fig. 2b.

The Bi metallurgy to filament conducting scheme was immediately obvious in TEM. The floor of the six to ten micron wide large crater was covered with ∼500Å thick Bi up to the lip of a minor crater, within which thinner, ∼200Å thick, Bi was continuous up to the filament.
Fundamental Research into Thin Films in a Developing Country
Authors: Eades J.A. , Grünbaum E.
Published: June 2020

In the last decade and a half, thin film research, particularly research into problems associated with epitaxy, has developed from a simple empirical process of determining the conditions for epitaxy into a complex analytical and experimental study of the nucleation and growth process on the one hand and a technology of very great importance on the other. During this period the thin films group of the University of Chile has studied the epitaxy of metals on metal and insulating substrates. The development of the group, one of the first research groups in physics to be established in the country, has parallelled the increasing complexity of the field.

The elaborate techniques and equipment now needed for research into thin films may be illustrated by considering the plant and facilities of this group as characteristic of a good system for the controlled deposition and study of thin films.
An Electron Microscope Study of Vapor-Liquid-Solid Growth in In and Sn Thin Films
Authors: Singh H. P. , Murr L. E.
Published: June 2020

Frankel concluded that evaporating atoms which settle and migrate on a substrate pass directly into the crystalline state, i.e. the initial stage of thin film formation is from vapor to solid (V→S). Semenov suggested that evaporating atoms settle, migrate on the substrate, form liquid nuclei, and crystallize at a later stage, i.e. growth is from vapor to liquid and then to solid [V→L(→S)]. This transformation would follow the thermodynamical step rule which states that a metastable system will transform into the next more stable state, and from this the transformation will take place to a stable state. Palatnik and Komnik examined bismuth films deposited onto glass plates with a temperature gradient and found that a substrate temperature , (Tm=melting temperature in °K) condensation proceeds by direct crystallization from vapor to solid (V-→S). For substrate temperatures , the condensation proceeds through an intermediate formation of liquid phase, i.e., V→L(→S).
Interpretation of Electrostatic Properties of Lunar Regolith
Authors: Asunmaa S. K. , Arrhenius G.
Published: June 2020

Evidence of a net surface charge on lunar regolith components and of their persistent internal polarization was discussed in a recent paper with references to charge significance for particle aggregation (Figs. 1-5); regolith dynamics; lunar dust storms; track density evaluation and albedo. The electret character observed appears to correlate with the irradiation and thermal history of the regolith. Electron microscopy provides direct evidence of microstructural features that promote internal polarization and preservation of charge.

The lunar dielectrics do not contain molecular dipoles. Elongated grains in the fines fraction tend to align in the direction of the field at sites of sufficient mobility (Figs. 3, 4, 5), suggestive of electric moments similar to those of polymeric materials whose molecular dipoles aggregate to form supramolecular dipoles. The number density and the distribution of free charge carriers obtained from the various ion implantations in the surface and subsurface layers (depending on particle energies) are heterogeneous and subject to charge redistribution in an applied field.
Structure Analysis from High Resolution EM Images
Authors: Iijima Sumio
Published: June 2020

So far the electron microscope has been far behind the X-ray diffraction method in crystal structure analysis. We have shown that under highly controlled imaging condition, it has been possible to take a two dimensional lattice images of niobium oxides, showing the arrangement of metal atoms at resolution of 3-4A, with a high resolution microscope equipped with a goniometer stage. The interpretation of such an image, which is very dependent on orientation of the crystal, specimen thickness and defocusing, has been reported and the detailed explanation of those images has been in progress by Fejes using n-beam dynamical theory. However, from the practical use of this two dimensional lattice image method, it can be said roughly the contrast of the image taken under so-called “optimum defocus condition”, shows a very good agreement with the projected potential of the crystal along the incident beam. Therefore, it will be possible to derive a crystal structure from high resolution images of unknown materials taken under “optimum defocus condition”.
High Quality Wide Field Imaging with JEM-100B
Authors: Shirota K. , Yanaka T.
Published: June 2020

Due to the field aberrations, mainly curvature of image field, astigmatism and field chromatic aberration, it is difficult to obtain a photograph which is of high quality from the center to the corners of the plate. But the aberrations vary greatly with the construction of lens system and the excitation modes of the lenses. This paper describes the possibility of high quality wide field imaging with the aberration minimised JEM-100B.

The width of over fringes Dsf caused by the curvature of image field and astigmatism, and the blur ΔF caused by the field chromatic aberration, both in the meridian plane, are given by the following equations based on Glaser's Blenden Freien System:

λ: wavelength, λ,K: constant, Ca...Fa,Cv,CF: aberration coefficient, xo: distance from the axis, α: angle of electron beam to the axis.
Image Theory and Image Processing
Authors: Welton T. A.
Published: June 2020

The fundamental problem of electron microscopy is the maximal extraction of object information from a noisy image. The noise-free image of course represents the object only with considerable distortion of several types. The electron microscope fails to transmit all spatial frequencies equally, and it can seriously distort local retardation and absorption values. In addition, a sample may have an essentially 3-dimensional structure compressed into a 2-dimensional display. We attempt to give a reasonably comprehensive theory of these effects, with a view to formulating a useful computational procedure for producing the best possible reconstruction of a sample from the available image data.

As the starting point, a theoretically sound treatment has been devised to replace the standard Abbe theory which, although enormously useful, has some difficulties. The wave equation is solved for a retarding and absorbing sample, immersed in a focussing field, on the reasonably valid assumption that the sample consists of a set of spherically symmetric elements (atoms).
Spatial Frequencies in Electron Images of Negatively Stained Protein
Authors: Flskin A. Max
Published: June 2020

Phase-noise which occurs in defocused Images of a negative stain layer has been extensively characterized, but usually in terms of an optical transform as averaged over fields of stain layer of an order of a tenth of a micron. We have found that adjacent fields of stain layer, if ranging from 100 to 200 A, frequently exhibit different spatial frequencies. We describe here the use of an optical autocorrelational technique by which to compare the spatial frequencies in images of negatively stained glutamic dehydrogenase (GDH) to those present in equivalent areas in the image of the surrounding stain layer.

Autocorrelational functions were recorded photographically as described previously, using the procedure developed by Meyer-Eppler and Darius. Several series of micrographs, each providing a through-focus set of data, were made of GDH negatively stained with 1% uranyl acetate on thin carbon substrates. Each micrograph was enlarged either by three or five steps of magnification with contrast enhancement.
New Aspects in the Design of Electron Optical Magnification Systems
Authors: Andersen Willem H.J.
Published: June 2020

Electron microscope design, and particularly the design of the imaging system, has reached a high degree of perfection. Present objective lenses perform up to their theoretical limit, while the whole imaging system, consisting of three or four lenses, provides very wide ranges of magnification and diffraction camera length with virtually no distortion of the image. Evolution of the electron microscope in to a routine research tool in which objects of steadily increasing thickness are investigated, has made it necessary for the designer to pay special attention to the chromatic aberrations of the magnification system (as distinct from the chromatic aberration of the objective lens). These chromatic aberrations cause edge un-sharpness of the image due to electrons which have suffered energy losses in the object.

There exist two kinds of chromatic aberration of the magnification system; the chromatic change of magnification, characterized by the coefficient Cm, and the chromatic change of rotation given by Cp.
Solid-Cadmium-Induced Cracking of Ti-6Al-4V Alloy
Authors: Meyn D. A.
Published: June 2020

Solid cadmium-induced cracking (SCIC) has been observed in titanium alloys and steels, and is a solid state analogue to liquid metal embrittlement. It is potentially inimical to titanium alloy utilization because titanium fasteners are cadmium plated to prevent galling, and aircraft structural parts of titanium alloys are usually assembled with cadmium plated steel fasteners.

Unnotched cantilever bend bars of Ti-6A1-4V solution treated and aged to 150,000 psi yield strength were loaded at 300°F (148°C) to 85,000 psi and 185,000 psi nominal bending stress in air with cadmium, steel, copper, or zinc pressed into the tension surface. After 100-200 hours, specimens in contact with cadmium cracked 0.025-in. to 0.040-in., regardless of the nominal bending stress. Identical cracking occurred in vacuum annealed (dehydrogenated) specimens. None of the other contact metals caused cracking. Figure 1 shows the fracture surface of a cadmium-cracked specimen. The “thumbnail” cracks consisted mainly of intergranular cracking and transgranular cleavage (Fig. 2).
Intensive Staining by Immersion Method
Authors: Nemeth Faye
Published: June 2020

Spurr Low-Viscosity embedding media provides superior infiltration of tissues, however difficulty in obtaining intense stains with lead and uranyl solutions by the flotation methods led to investigation of immersion procedures. The reported method permits staining of both surfaces of the section, is easy to perform, does not take too long a time, and routinely gives intensely stained specimens with a minimum of precipitation.

Method: A stender dish is prepared for use by placing a smaller Petrie dish inside of the stender dish and pouring Indicarb (Fisher Scientific Co.) around the periphery. The Petrie dish provides a platform for staining, and the Indicarb absorbs the CO2. The stender dish should have a tight cover.

Staining dishes are prepared by using Lucite bars with drilled holes as suggested by Feldman and described by Pease Serological plates with deep wells, at least 3 to 4 mm. in depth can also be used to provide support for the paraffin.
Molecular Imaging in High Electric Fields
Authors: Panitz J. A.
Published: June 2020

For the past thirty years, attempts have been made to use the field-electron emission microscope (FEEM), and the field-ion microscope (FIM) to image organic molecules. These attempts were inspired by the simplicity of the techniques and the potential for achieving high image contrast, magnification, and resolution. Since both microscopies rely on direct point projection for imaging, there is no need for electron-lens systems or devices to minimize specimen vibration. As a result, both techniques offer the hope of achieving high quality molecular images with a minimum of effort.

In the early 1950's the FEEM was the only microscope which had demonstrated a magnification of 106 at an image resolution better than 2nm. Since it had already been used to image the diffusion of monomolecular films on clean metal surfaces, there was growing optimism that individual organic molecules could be imaged as well. In 1951, striking FEEM patterns of flaventhrene and copper-phthalocyanine were obtained which displayed the known symmetry of each molecule (two-fold and four-fold, respectively). Unfortunately, the success of these experiments was relatively shortlived.
Investigations of Defective β-NiAl by Transmission Electron Microscopy
Authors: Liu H. C. , Chang E. , Mitchell T. E.
Published: June 2020

The β-NiAl phase, which is an ordered B2 structure, covers a wide range of compositions extending from ∼46 at.% Ni to ∼60 at.% Ni. For non-stoichiometric β-NiAl, studies (1,2) have shown that, for compositions below 50 at.% Ni, structural vacancies are introduced on the Ni sublattice (denoted as VNi), but for compositions above 50 at.% Ni,excess Ni atoms replace A1 atoms on the A1 sublattice (denoted as NiAl). In this work, defect structures in compositions of 45, 45.5, 46, 47, 50, 55, 58 and 60 at.% Ni were studied by electron diffraction techniques in a Siemens 102 TEM.

Figs. 1 and 2 show selected area diffraction patterns at the exact [011] and [001] zone axes respectively.
In Situ Observation of Catalyzed Gasification of Graphite by Nickel
Authors: Baker R. T. K. , Sherwood R. D.
Published: June 2020

The catalytic gasification of carbon at high temperature by microscopic size metal particles is of fundamental importance to removal of coke deposits and conversion of refractory hydrocarbons into fuels and chemicals. The reaction of metal/carbon/gas systems can be observed by controlled atmosphere electron microscopy (CAEM) in an 100 KV conventional transmission microscope. In the JEOL gas reaction stage model AGl (Fig. 1) the specimen is positioned over a hole, 200μm diameter, in a platinum heater strip, and is interposed between two apertures, 75μm diameter. The control gas flows across the specimen and exits through these apertures into the specimen chamber. The gas is further confined by two apertures, one in the condenser and one in the objective lens pole pieces, and removed by an auxiliary vacuum pump. The reaction zone is <1 mm thick and is maintained at gas pressure up to 400 Torr and temperature up to 1300<C as measured by a Pt-Pt/Rh 13% thermocouple. Reaction events are observed and recorded on videotape by using a Philips phosphor-television camera located below a hole in the center of the viewing screen. The overall resolution is greater than 2.5 nm.
Preliminary Electron Microscopic Study of Thermal-Shock-Resistant Ceramic-Metal Composites
Authors: Lauf R. J. , Morgan C. S.
Published: June 2020

Ceramic-metal composites, or cermets, are used for a variety of applications. In general, the ceramic phase provides hardness or wear resistance while a continuous metal phase acts as a binder and provides toughness. The alumina-based cermets described here are unique in that the metallic phase (platinum) is discontinuous and constitutes only about 1 to 2 vol % of the structure. This material was developed to serve as a high-temperature electrical insulator under conditions of severe thermal shock. Because of the small grain sizes involved, electron microscopy was used to study the relation between properties and process variables as well as to better understand the mechanism of thermal shock resistance.

Platinum was intimately mixed with alumina powder by precipitation from a PtCl4 solution followed by drying. The resulting powder mixture was hot-pressed in a graphite die at 1610°C for 15 min under 69 MPa (10,000 psi) pressure. Cermets produced from Alcoa A-17 alumina powder had a final grain size of 15 ± 4 μm, while Fisher Scientific reagent-grade alumina resulted in a grain size of 4 ± 1 μm. The platinum particles ranged from 0.2 to 1.0 μm in diameter. Thermal shock resistance was tested by heating the cermet to 520°C and quenching in hot water. Cermets that were gastight after 15 quench cycles were considered acceptable. Thermal shock resistance was improved by heating the as-pressed pellet to 1630°C and air cooling.
TEM Studies of Crystalline Minerals in Mt. St. Helens Ash
Authors: Rice L. , Dash J.
Published: June 2020

Mount St. Helens ash is a pumaceous, pyroclastic material which has been dispersed in varying amounts over most of the Pacific Northwest on a number of occasions during 1980, including the catastrophic eruption of May 18 1980. Samples have been collected and examined from several sites between the crater itself and northwestern Oregon from March 20, 1980 through October 17, 1980. Ejected material consists of both older mountain and new particles. Tephra composition varies in proportions of glass and glass-coated minerals with length of plume travel time. Portland area fallout has ranged from coarse, steel gray, low in glass on June 12, 1980 (travel time two hours) to fine, talcy, brownish gray, high in glass on May 25, 1980 (travel time six to eight hours).

Crystalline, sub-micron sized particles of the ash are being studied by the selected-area electron diffraction technique with the TEM in an effort to determine the nature of the mineral content of the ash. The particles are deposited on carbon-coated grids containing small pieces of evaporated gold film for determination of accurate camera constants. Several plagioclase feldspar minerals (70-75% of the mineral fraction for Cascade volcanoes) have been identified from random samples of the atmospheric fallout.
A SEM and EDS Study of Manganese Nodules From the Northwest Atlantic
Authors: Berry V.K. , Addy S.K.
Published: June 2020

In a recent study of micronodules from the red clay province on the Abyssal Hills of Northwest Atlantic the micronodules were generally found to be bo-tryoidal clusters of concentric “ compact balls” fused in a coarse grained friable “Porous Cement.” It is believed that the compact balls which have higher Mn content than Fe, were formed by direct precipitation of ferromanganese oxide from the sea water at the sediment water interface and later joined with each other by a porous cement containing higher Fe and clay content. In the present studies two groups of nodule samples were used to compare their morphology and chemistry with the micronodule samples studied earlier. The samples from one group were collected from the Abyssal Hills-the red clay area and the second group from the Bermuda High-the foraminiferal clay area.

The location and the depths of the four samples studied here are (1)28°46.2'N, 60°20.5'W, 5359 meters, (2)27°01.5'N, 58°49.8'W, 5087 meters, (3)31°16.07N, 67°37.99'W, 4590 meters and (4)same as (3) but different location in the vicinity. The nodule samples varied in size from ½” to 3” in diameter. The sample pieces were mounted on a carbon planchet with silver paste and sputtered with ∼200Å of AU/Pd, before transferring to the microscope. Both the outside surface of the nodules and the inside surface (after cutting open with a sharp blade) were examined in JEOL JSM-35 SEM fitted with Nuclear Semiconductor Si (Li) x-ray detector and Tracor Northern NS-880 Analysis System. The microscope was operated at 25kV acc. voltage in the secondary electron emission mode. The x-ray spectra were taken in 0-10 keV range with total count time of 100 sec.
TEM Study of a Tilt Boundary in Hot-Pressed Silicon
Authors: Carter C. B. , Rose J. , Ast D. G.
Published: June 2020

The hot-pressing technique which has been successfully used to manufacture twist boundaries in silicon has now been used to form tilt boundaries in this material. In the present study, weak-beam imaging, lattice-fringe imaging and electron diffraction techniques have been combined to identify different features of the interface structure. The weak-beam technique gives an overall picture of the geometry of the boundary and in particular allows steps in the plane of the boundary which are normal to the dislocation lines to be identified. It also allows pockets of amorphous SiO2 remaining in the interface to be recognized. The lattice-fringe imaging technique allows the boundary plane parallel to the dislocation to be identified. Finally the electron diffraction technique allows the periodic structure of the boundary to be evaluated over a large area - this is particularly valuable when the dislocations are closely spaced - and can also provide information on the structural width of the interface.
Some Observations on Core Edge Fine Structure and Orientation Dependent Effects in Inelastic Electron Scattering
Authors: Grunes L. A. , Leapman R. D. , Ray A. B. , Silcox J.
Published: June 2020

In this paper we review experiments carried out at Cornell University in recent years concerning fine structure in core edges and effects in cross sections that relate to orientation dependent effects on inelastic electron scattering in crystals. The experiments are primarily of an exploratory character but do demonstrate how inelastic scattering could be of value in studies of oxidation in transition metals. They also indicate how characteristics such as the directionality of a final state Π* orbital or peaks in the final density-of-states appear in the spectra. Finally, at low energy losses the orientation dependence can be related to anisotropic effects in the optical constants.

The experiments were carried out in a Hitachi HU-llA-Wien electron spectrometer system described previously. For present purposes, the role of the electron microscope is to provide a sophisticated electron optical bench which, using small angle scattering geometry, can explore scattering angles below 3x10-4 radians at angular resolutions of 10-5 radians (corresponding to a wave vector change of k0θ≃0.0015 Å-1).
Electron Energy Loss Spectroscopy of Surfaces and Interfaces
Authors: Krivanek O. L.
Published: June 2020

The structure of bulk surfaces can be studied by reflection electron microscopy and the structure of interfaces in thin foils by TEM. Both methods are capable of nearly atomic-level resolution. This paper explores whether the structural information can be supplemented with chemical and electronic information by the use of electron energy loss spectroscopy.

Energy loss spectra from the surface of bulk Be have been obtained at 35kV primary energy by Klein, and spectra of the Si surface at 14.2kV have been obtained by Schilling, who also demonstrated that the relative strength of the volume and the surface plasmon can be altered by changing the reflection geometry.

Fig. 1 contains two energy loss spectra obtained in surface reflection from (100) Si at 100kV in a standard TEM (Philips 400) with a magnetic sector energy analyzer (Gatan 607), and a diagram showing the geometry of the incident beam and the beam admitted into the spectrometer relative to the surface.
Digital Image Processing of High Resolution 500KV Micrographs
Authors: Kirkland E.J. , Siegel B.M. , Uyeda N. , Fujiyoshi Y.
Published: June 2020

The predominate linear components of a defocus series of bright field phase contrast electron micrographs of a thin specimen may be represented in Fourier space as;

(1)

If there are m micrographs in the series then are m dimensional vectors, each component of which represents one micrograph. is the Fourier transform of the recorded defocus series and is the random noise content of is an mx2 matrix representing the transfer functions of the microscope (including spherical aberration, defocus, and partial coherence). is a two component vector representing the two components (real and imaginary) of the ideal unaberrated phase contrast image, is a two dimensional spatial frequency vector in the image plane.
Comments on the Computerization of an Analytical Electron Microscope
Authors: Fiori C.E. , Gorlen K.E. , Gibson C.G.
Published: June 2020

The digital computer has had a dramatic impact on most specialties of science, and electron microscopy is no exception. Until quite recently the majority of applications in electron microscopy involve the digitization of a transmission micrograph recorded on a photographic emulsion. Such digitization is carried out by a device such as a rotating drum or flat bed microdensitometer or a flying spot scanner. Subsequent processing of the digitized image is carried out in a large central computer. It was obvious from the beginning that the output from a scanning mode microscope could be directly digitized. There have recently been several reports of such work now that computers with sufficient memory, mass storage, and speed have become available at an acceptable cost (see, for example, references 2, 3, 5). Our own laboratory has nearly completed the hardware interface of a Digital Equipment Corporation PDP 11-60 mini-computer to a 200 keV analytical electron microscope (Hitachi H700H). In this paper we will discuss several factors regarding the overall design of such a system.
Electron Diffraction Applied to the Study of the Structure of (110) Tilt Boundaries in Fe-3% Si
Authors: Hall E. L. , Briant C. L. , Walter J. L.
Published: June 2020

It has become clear in recent years that both low-angle and high-angle grain boundaries can be described in terms of periodic structures. It has also been shown that much useful information concerning the structure of grain boundaries can be obtained by a combination of imaging and electron diffraction in the TEM. In the present study, these techniques are applied to the investigation of grain boundaries in high-purity Fe-3% Si. This material was chosen since very little work has been done to date on the structure of boundaries in bcc materials, and because it was possible to produce nearly pure (110) tilt boundaries with a wide range of angular misorientation in this material by a series of rolling and annealing treatments.

The geometry of electron diffraction effects associated with grain boundaries has been extensively described in the literature. In the case of a boundary which is parallel to the electron beam and which has a periodicity present with a direction and a spacing P, a row of spots will occur in reciprocal space at each matrix reflection with a direction and a spacing 1/P.
Thin Foil Viewing Screens and On-Line Computer as HVEM Focusing Aids
Authors: Pawley J. , Neuberger D. , Hanrahan P.
Published: June 2020

Because 1 MeV electrons have a mm range in the A1 viewing screen substrate, the screen image is dim and of low resolution/contrast (CTF). This makes it difficult to focus and, at higher magnification, to stigmate. This paper describes improvements both to the normal viewing screen and to a low light level TV viewing system as part of an ongoing improvement program.

Improvements in viewing screen performance have been handicapped by the lack of a simple method of measuring screen CTF. In the only careful study, Camps and Cosslett used the microscope lenses to form a spot on the screen and this was then scanned in a fan-shaped raster. The raster was photographed through the viewing window and the negative then analyzed at different line spacings with a microdensitometer. Unfortunately, this study only analyzed the effect of phosphor type and thickness and did not consider the thickness and atomic number of the substrate.
High-Temperature Dislocation Structures in Cyclically Deformed Pure Iron
Authors: Pak H-r. , Meshii M.
Published: June 2020

In an effort to understand the inverse (positive) temperature dependence of cyclic stress of purified iron (Fig. 1), the dislocation structures developed during cyclic deformation were studied as a function of the number of cycles and deformation temperature. Cylindrical specimens were prepared from MRC-VP grade iron rods by machining to produce the reduced gage section of 6.1 mm in diameter and 5.1 mm in length. The specimens were purified for 3 days at 1033K in a ZrH2 furnace to reduce the interstitial concentration to less than 1 at.ppm. The grain size after this treatment was 200 μm. The specimens were cycled in tension-compression at a constant total strain amplitude of ± 10-3 at a strain rate of 10-3S-1 in a purified argon atmosphere at 298, 473, 673 and 903K. Thin foils were prepared from discs sliced perpendicular to the stress axis by jetpolishing and final polishing in a perchloric acid-acetic acid solution and were examined in a Hitachi HU-200E electron microscope at 200kV.