bluuebunny/crossref_metadata_2025_split huggingface dataset:
The orientation effect on amorphization in CoTi under 1 MeV electron irradiation
Authors: Xu Genbao , Meshii M. , Okamoto P. R. 
Published: June 2020

Since the first report of electron irradiation induced amorphization in 1982, this phenomenon has been characterized in many aspects. The effects of the dose and temperature, the mass of the incident beam, the deviation from stoichiometry and the electron flux, have been studied. There is, however, no systematic study has been reported on the crystallographic orientation effects. This paper will report the orientation effect on amorphization of intermetallic compound CoTi irradiated by 1 MeV electrons.An alloy button of Co-45 at.% Ti was prepared by arc-melting and subsequently annealed at 1100°C for ten days. The HVEM samples were spark-cut from the button and then thinned by double jetpolishing in the solution of 15%HCLO4and methanol. The irradiation was carried out with fully focused 1 MeV electron beam in a high voltage electron microscope. The critical electron dose for complete amorphization and its temperature dependence have been determined for <111>, <110> and <001> orientations.
The Demonstration of Human Prostatic Acid Phosphatase (Pap) With Phosphorylcholine
Authors: Serrano José A. , Wasserkrug Hannah L. , Serrano Anna A. , Seligman Arnold M. 
Published: June 2020

As previously reported (1, 2) phosphorylcholine (PC) is a specific substrate for prostatatic acid phosphatase (PAP) as opposed to other acid phosphatases, e.g., lysosomal acid phosphatase. The specificity of PC for PAP is due to the pentavalent nitrogen in PC, a feature that renders PC resistant to hydrolysis by all other acid phosphatases. Detailed comparative cytochemical results in rat tissues are in press. This report deals with ultracytochemical results applying the method to normal and pathological human prostate gland.Fresh human prostate was obtained from 7 patients having transurethral resections or radical prostatectomies. The tissue was fixed in 3% glutaraldehyde- 0.1 M cacodylate buffer (pH 7.4) for 15 min, sectioned at 50 μm on a Sorvall TC-2 tissue sectioner, refixed for a total of 2 hr, and rinsed overnight in 0.1 M cacodylate buffer (pH 7.4)-7.5% sucrose.
Electron Cytochemical Study of Corneal Epithelial Repair After Carbon Dioxide Laser Damage
Authors: Tsou K. C. , Severdia J. , Stuck B. , Beatrice E. 
Published: June 2020

Investigation of laser damage to the eye relies mainly on electron microscopy because of the limitation of the amount of tissue available for such study and the low level of damage that is discernible only under the electron microscope (1). Previously, we showed that functional damage to Rhesus monkey cornea epithelium by carbon dioxide laser could be studied with cytochemical methods adaptable to electron microscopy (2). The present paper reports repair of corneal epithelium in Rhesus monkey, following treatment by carbon dioxide laser.Rhesus monkey corneas were divided into three sections: the damaged area in the center (Area 1), the adjacent area (Area 2), and the area next to the sclera region (Area 3). The tissues were fixed in 3% glutaraldehyde in 0.25 M sucrose overnight for NADH diaphorase (2) and Mg++-ATPase (3) study, and postosmicated with 1% Os04in cacodylate buffer. Lasing effect could not be seen visually after 24 hrs.
An Aortitis of Knots Caused by a Besnoitia-Like Agent
Authors: Simpson C. F. , Woodard J. C. , Forrester D. J. 
Published: June 2020

An epizootic among knots (Calidrus canutus)on the Gulf coast of Florida was characterized by considerable mortality. From a histologic study of birds that died, it was concluded that the etiologic agent of the disease was an encysted sporozoan parasite closely associated with the endothelium of the thoracic aorta. The parasitized aortas were examined with the electron microscope in order to characterize the agent involved.In 1 μm sections of plastic embedded artery examined with the light microscope, it was observed that the etiologic agent was a multinucleated cyst which was closely associated with, or attached to, the luminal aspect of the aorta. The cyst consisted of four layers (Fig. 1). The most internal layer was a central area of vacuolization which contained a round body. The second most peripheral layer contained several nuclei.
Ultrastructural Alterations in Sinusoidal Endothelial Fenestrae as a Result of Hypoxia
Authors: Nopanitaya Waykin , Brown Raeford E. , Grisham Joe W. , Carson Johnny L. 
Published: June 2020

Mammalian endothelial cells lining hepatic sinusoids have been found to be widely fenestrated. Previous SEM studies (1,2) have noted two general size catagories of fenestrations; large fenestrae were distributed randomly while the small type occurred in groups. These investigations also reported that large fenestrae were more numerous and larger in the endothelial cells at the afferent ends of sinusoids or around the portal areas, whereas small fenestrae were more numerous around the centrilobular portion of the hepatic lobule. It has been further suggested that under some physiologic conditions small fenestrae could fuse and subsequently become the large type, but this is, as yet, unproven.We have used a reproducible experimental model of hypoxia to study the ultrastructural alterations in sinusoidal endothelial fenestrations in order to investigate the origin of occurrence of large fenestrae.
Human Enamel Replication
Authors: Dockum Norman L. , Dockum John G. 
Published: June 2020

Ultrastructural characteristics of fractured human enamel and acid-etched enamel were compared using acetate replicas shadowed with platinum and palladium. Shadowed replications of acid-etched surfaces were also obtained by the same method.Enamel from human teeth has a rod structure within which there are crystals of hydroxyapatite contained within a structureless organic matrix composed of keratin. The rods which run at right angles from the dentino-enamel junction are considered to run in a straight line perpendicular to the perimeter of the enamel, however, in many areas these enamel rods overlap, interlacing and intertwining with one another.
Fine Structure of Planarian Neuroglial Cell
Authors: Morita Michio , Best Jay Boyd 
Published: June 2020

The species of the planarian Dugesia dorotocephala was used as the experimental animal to study a neuroglial cell in the ventral nerve cord. Animals were fixed with 3% buffered glutaraldehyde solution and postfixed with 1% buffered osmium tetroxide.The neuroglial cell is multipolar, expanding into three or four cytoplasmic processes with many daughter branches. Some neuroglial processes are found to extend perpendicular to the longitudinal nerve fibers, whereas others are seen to be parallel to them. The nucleus of the neuroglial cell is irregular in shape and frequently has a deep indentation. Convex portions of the nucleus seem to be related to the areas from which cytoplasmic processes are extended. Granular endoplasmic reticulum (Fig. 4), Golgi body (Fig. 2), mitochondria (Figs. 1 and 2), microtubules (Fig. 4), and many glycogen granules are observable in the electron dense neuroglial cytoplasm. Neuroglial cells are also observed to contain various sizes of phagosomes and lipids (Fig. 2).
Cell Junctions in the Hepatopancreas of the Isopod, Armadillidium Vulgare
Authors: Gonzalez Marcia Vega 
Published: June 2020

An ultrastructural study of the hepatopancreas of the terrestrial isopod, Armadillidium vulgare, indicates that morphological change in intercellular membrane apposition parallels functional differention of cells. In the isopod the midgut is structurally and functionally represented by the hepatopancreas. Each of the four lobes of this structure is histologically differentiated into regenerative, transitional and glandular regions, which progress from the distal to the proximal end respectively, and then connect through ducts to the hindgut.The distribution of cellular organelles is similar in all cells of the regenerative region. Plasma membranes of adjacent cells are separated by a distance of 160 A, (fig. 1). There is no indication of specialized membrane apposition such as junctional complexes or gap junctions. The cell membranes do not exhibit infoldings or extensive convolutions.
Visualization of Surface-Associated Nucleic Acid in Tumoricenic Cells Using Ultrathin Frozen Sections and Platinum-Pyrimidine Complexes
Authors: Aggarwal Surinder K. 
Published: June 2020

Platinum-pyrimidine complexes have been used as sole electron-dense stains for electron microscopy on number of mammalian cells (1-3) . They are selective for areas rich in nucleic acids and stain the cellular chromatin, ribosomes and nucleolus. Tumorigenic cells exhibit special binding on the plasma membrane surface in the form of dense patches; normal cells do not. Solid tumor biopsy samples from animals and humans show similar patches but only in malignant tissues. Various enzymatic studies suggest that the electron-dense patches are DNA with neuraminic acid involved in the binding. Autoradiographic studies using H3-thymidine confirms the presence of surface- associated DNA.Swiss Webster mice bearing ascites sarcoma-180 tumor are given intraperitoneal injection of 7. 0 μ c of tritiated thymidine in 0. 5 ml sterile 0. 85% NaCI on day 5 of the tumor implant.
Normal Rat Urinary Bladder: Developmental Variations in Surface Contour
Authors: Malick Linda E. 
Published: June 2020

Since rats, hamsters and mice are commonly used for testing potential carcinogens, a study of the normal surface structure of urinary bladder epithelium of different age animals was undertaken to provide a basis of comparison for long term studies of animals with experimentally treated bladders. Scanning electron microscopy (SEM) provides a unique opportunity to rapidly detect and map out altered cell surfaces.Healthy albino rats from the 17th day of gestation to 7 months of age were anesthetized. The abdominal cavity of each animal was opened and the urinary bladder perfused in situ with 2.5% buffered glutaraldehyde, pH 7.4.
Fenestrations in Normal and Oxidant-Exposed Alveolar Walls in the Lungs of Exercising Squirrel Monkeys.
Authors: Bils Robert F. 
Published: June 2020

The significance of the lung alveolar pores of Kohn has been discussed in great detail. Though not proven conclusively, the assumed function of these pores or fenestrations is that of collateral ventilation in the event of airway obstruction (1). Boatman and Martin (2) concluded that the alveolar pores in the dog lung were lined with alveolar epithelium, and that many of the alveolar pores had epithelial junctions on one or both sides of the pores.Squirrel monkeys were exposed to 0.6 ppm ozone for 4 hours per day for 4 days with intermittent exercise in a rotating cylinder. Following standard procedures for processing the lung tissues for TEM and SEM (3), alveolar walls of exposed and control animal lungs were studied. Pathological lesions were focal and centroacinar involving both the terminal bronchioles and alveoli. Normal alveolar wall fenestrations (Pores of Kohn) were seen in the control tissues, but they were significantly increased in number and size after exposure 4 days consecutively.
Morphometry Evaluation & Ultrastructure of the Lungs of Rats Exposed to Low Levels of Ozone
Authors: Boatman E.S. 
Published: June 2020

Ozone (O3) is one of the principal oxidants formed in polluted air. It is a highly reactive gas which readily attacks biological tissues to give rise to a diversity of changes, both marked and subtle. The effects of prolonged exposure to low concentrations of O3 on the function and structure of the lungs is a subject of considerable interest and speculation.This study is concerned with the functional, structural and morphometric changes in the lungs of rats exposed to 0.45 ppm of 03 for 6 hrs/day, 5 days/ week for up to 10 weeks.Lungs were fixed at a constant distending pressure of 25 cm of water with 0.1M sodium cacodylate buffered 1.5% glutaraldehyde pH 7.4 for 18 hours, sliced transversely and post fixed in buffered 1.0% osmium tetroxide. Tissue slices from left and right lungs were embedded in epoxy resin, sectioned at l.0μ and stained with azure II methylene blue.
Alteration of Mitochondria in Oxythiamine-Induced, Acute Thiamine Deficiency in the Mouse
Authors: Watanabe Itaru , Scarpelli Dante G. 
Published: June 2020

Acute thiamine deficiency was produced in mice by the administration of oxythiamine, a thiamine analogue, superimposed upon a thiamine deficient diet. Adult male Swiss mice (30 gm. B.W.) were fed with a thiamine deficient diet ad libitumand were injected with oxythiamine (170 mg/Kg B.W.) subcutaneously on days 4 and 10. On day 11, severe lassitude and anorexia developed, followed by death within 48 hours. The animals treated daily with subcutaneous injections of thiamine (300 μg/Kg B.W.) from day 11 through 15 were kept alive. Similarly, feeding with a diet containing thiamine (600 μg/Kg B.W./day) from day 9 through 17 reversed the condition. During this time period, no fatal illness occurred in the controls which were pair-fed with a thiamine deficient diet.The oxythiamine-treated mice showed a significant enlargement of the liver, which weighed approximately 1.5 times as much as that of the pair-fed controls. By light and electron microscopy, the hepatocytes were markedly swollen due to severe fatty change and swelling of the mitochondria.
Gallstone Ultrastructural Analysis
Authors: McConville R.L. , McConville B.E. 
Published: June 2020

A detailed knowledge of the structure of gallstones is important since the gallstones contain a record of those changes in the tody which influence the function of the liver and the gallbladder, and since 15-20 million people in the United States alone, suffer from the disease (l), investigations leading to a “better understanding of the disease is a worthwhile endeavour.A study of one of the most common categories of gallstone is reported here:- a mixed stone of cholesterol and calcium carbonate from a multiple deposit. This was a small (approx. 0.8 cm. diameter) off-white, spherical stone with a heavily pigmented centre. The stone was prepared and analysed using the scanning electron microscope (S.E.M.) together with energy dispersive X-ray analysis in the manner used for urinary calculi (2).
Rapid Chemical Dehydration of Mammalian Tissues for Scanning Electron Microscopy using 2 ,2-Dimethoxypropane
Authors: Maser Morton D , Trimble John J. 
Published: June 2020

Muller and Jacks used 2,2-dimethoxypropane (DMP) as a dehydrating agent for biological specimens prior to embedment, ultrathin sectioning, and examination by transmission electron microscopy. Acidified DMP reacts endothermically with water to produce methanol and acetone. Muller and Jacks demonstrated excellent fine structural preservation in a variety of specimens dehydrated with DMP.We have used the same method, prior to critical point drying, to prepare specimens for scanning electron microscopy (SEM) . Portions of the trachea, small intestine, and kidney from a laboratory mouse killed by cervical dislocation were fixed for 16 hours in cold 3% glutaraldehyde in 0.1 M phosphate buffer, pH 7.2.
Preparative Techniques for Sem Examination of a Smooth Plastic Fabricated for use as a Blood-Handling Surface
Authors: Kurusz M. , Mumaw V.R. , O'Bannon W. , Donachy J.H. , Pierce W.S. 
Published: June 2020

Efforts are underway to develop a left ventricular assist pump and total artificial heart for use in patients with end-stage cardiac disease. The blood-handling material in both devices is a smooth elastomer of the segmented polyurethane family that has excellent mechanical, chemical, and biological properties when used in animal studies. However, a persistent problem with any artificial blood-handling device is activation of the coagulation system and the development of thrombo-emboli.Scanning electron microscopy was used to evaluate the microtopography of the plastic surfaces for baseline information and to compare the effects of different fabrication techniques upon surface finish prior to implantation of assist devices in bovines. Defining surface smoothness is difficult, but it is believed that thrombo-resistant surfaces must not have any defects larger than the diameter of blood platelets (2-4μm).
UHV In-Situ Electron Microscopy of thin Film Growth
Authors: Yagi K. , Takayanagi K. , Kobayashi K. , Honjo G. 
Published: June 2020

An ultra-high vacuum (UHV) electron microscope was constructed for special purpose of in-situ studies of thin film growth and some experimental results have already been published (1). Here, recent results are described.1. Au/graphite (nucleation and growth mode). Growths of Au in a dendritic shape at 150°C were observed on graphite. The dendritic morphology was said to be characteristic of the Au growth on UHV cleaved graphite (2). We cleaned an air cleaved surface by heating in UHV EM (10-8 torr) for 20 minutes prior to the Au deposition. The dendritic shape growth in Fig. 1, therefore, indicates that the graphite surface became clean with the present heat treatment and that the in-situ studies were done under clean conditions.
Image Simulation of Dislocation Loops
Authors: Ohr S. M. 
Published: June 2020

Computer simulation of image contrast is a useful tool in the identification of lattice defects observed in the electron microscope. In order to obtain high quality simulated micrographs, it is necessary either to consume a considerable amount of computer time or to have the micrographs processed through special photographic devices. In this paper, we describe a numerical scheme by which half-tone simulated images of dislocation loops can be constructed with efficient use of computer time and without special photographic handling.We have solved the Howie-Whelan two-beam dynamical equations by the extrapolation method of Bulirsch and Stoer which has been shown to be about six times faster than the Runge-Kutta method. The method evaluates the transmitted and diffracted intensities at the bottom surface of the foil as a function of step size. The final solution is obtained by forcing the convergence of this sequence of solutions to the limit.
Dynamic Dark-Field Electron Microscopy
Authors: Haydon G.B. , Crane R.A. , Zercher C.R. 
Published: June 2020

Dynamic dark-field electron microscopy as described here provides capabilities not present with other methods. An annular ring of any selected diameter is used to illuminate the specimen. Diffraction rings selected by the objective aperture are integrated photographically to produce the dark-field image.All methods of dark-field electron microscopy eliminate the incident illumination from the image and utilize only a selected portion of the scattered electrons and each has its limitations (1):1. Movement of the objective aperture off of the optical axis introduces spherical aberation which increases as the 4th power of the distance from the axis.2. Tilting the beam either mechanically or electrically allows only those electrons scattered in one direction to be imaged.
Some Observations on the Adsorption of Heavy Atoms on Carbon Substrates
Authors: Isaacson M. S. , Kopf D. , W. Parker N. , Utlaut M. 
Published: June 2020

In previous papers we have shown that the use of the atomic resolution STEM to study adsorption of heavy atoms on light element substrates could be of potential value in surface science. We indicated that we had undertaken a program to determine to what extent that was true and that one particular measurement we were attempting was to measure adatom-adatom spacing distributions. In this paper we would like to present some further results and also discuss the general validity of our approach.At present, our specimens are made by depositing 5 μl of a 10-4 - 10-5 M solution of a heavy-atom-containing molecule onto a thin carbon film. The drop is allowed to sit for about 20 seconds and then pipetted off the film. This results in the heavy atoms being deposited within a molecule and so if the molecule remains intact, the preferential spacings between heavy atoms which may be observed could be dependent upon the molecule.
A Field Emission Probe Forming System with a Magnetic Pre-Accelerator Lens
Authors: Pei Kuo Huei , Siegel Benjamin M. 
Published: June 2020

A field emission electron probe forming system with a magnetic preaccelerator lens has been developed.The magnetic lens has been designed using computer optimization for best compromise between high lens quality, ease of tip manipulation and tolerable power dissipation of the exciting coil. Figure 1 shows the configuration of the magnetic lens and the field emission tip assembly. The optical properties of the magnetic lens are plotted in Figure 2.The performance of the magnetic pre-accelerator lens was evaluated with a prototype electron optical bench developed by Veneklasen. It consists of a two cylinder accelerator, a magnetic transfer lens and a projector lens followed by a razor blade assembly for measurement of the spot size and the beam current.
Electron Metallography Methods Applied to Studies of Recovery and Recrystallization in Rolled Tantalum Single Crystals
Authors: Johnson D. H. , Snyder W. B. 
Published: June 2020

Recovery and recrystallization studies of deformed tantalum single crystals show widely varying recrystallization behavior. Image analysis methods, utilized to quantitatively characterize changes, are described; advantages in precision, reproducibility, and operator time were realized over conventional methods. The data obtained compared well with previous data for niobium.Dislocation densities were measured by placing bright field micrographs in the scanner of an image analyzing microscope; the contrast was adjusted to differentiate the dislocations; and their area fraction (total line length) measured directly. The projected line length, A, of dislocations was corrected to total line length by multiplying by a shape factor. Foil thickness, t, was determined by counting thickness fringes from the edge of the perforated hole.
Aperture Dependence of Resolution and Beam Transmission in High-Voltage Tem of Thick Biological Specimens
Authors: Fotino Mircea 
Published: June 2020

In standard transmission electron microscopy the image is formed by electrons scattered both elastically and inelastically within the specimen. Their relative contributions to the image quality are determined by electron energy, specimen thickness and vertex half angle a of the collection cone defined by the objective aperture.The cross sections for scattering into a given angle decrease as the electron energy increases to the MeV region (1), and the accompanying increased preponderance of the elastic component results in improved resolution in the image of thin objects.In most biological applications of high-voltage electron microscopy the usual thickness range (0.25-5.0 μn) is such that plural scattering within the specimen becomes the dominant factor for resolution and contrast (e.g.(2)). In particular, increased fractions of electrons are removed from the transmitted beam by scattering outside the collection cone.
Reduction of Specimen Contamination in Electron-Beam Instruments
Authors: Lehmpfuhl G. , Smith P. J. 
Published: June 2020

Specimens being observed with electron-beam instruments are subject to contamination, which is due to polymerization of hydrocarbon molecules by the beam. This effect becomes more important as the size of the beam is reduced. In convergent-beam studies with a beam diameter of 100 Å, contamination was observed to grow on samples at very high rates. Within a few seconds needles began forming under the beam on both the top and the underside of the sample, at growth rates of 400-500 Å/s, severely limiting the time available for observation. Such contamination could cause serious difficulty in examining a sample with the new scanning transmission electron microscopes, in which the beam is focused to a few angstroms.We have been able to reduce the rate of contamination buildup by a combination of methods: placing an anticontamination cold trap in the sample region, preheating the sample before observation, and irradiating the sample with a large beam before observing it with a small beam.