bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved stability of alkali metals on catalysts during analytical electron microscopy
Authors: Reuter Kathleen B. , Lyman Charles E. 
Published: June 2020

Determination of the location and quantity of poison or promoter elements on catalyst surfaces is an ideal application for the high spatial resolution available on the analytical electron microscope (AEM). However, these elements are often unstable under an electron beam making them difficult to detect consistently. This paper describes a method to enhance the stability of cesium, a mobile alkali metal, on the surface of a catalyst using a thin coating of chromium.The catalyst in this study was MoS2 doped with 5.3 wt% CsOOCH (4.8 mol% Cs) which is used for alcohol synthesis. After grinding with a mortar and pestle and spreading between glass slides, the Cs/MoS2 was supported on a carbon coated Cu grid. The Cs/MoS2 particles were coated with 10nm of Cr using a VCR Group, Inc. ion beam sputterer model IBS/TM200. During sputtering, the vacuum produced by a turbo pump and LN2 cold trap was better than 10-5 torr and the sample was continuously rotated and tilted.
Electron microscopy on biaxially oriented PET films
Authors: Gohil Ramesh M. 
Published: June 2020

In order to understand properties of biaxially oriented PET films, it is necessary to understand the genuine morphology of the films. Inspite of previous extensive studies, our knowledge of the exact nature of PET crystals, their reorganization during heat treatment, and their relevance to the properties is not clearly understood. Therefore, the present study was undertaken to investigate characteristics of PET crystals using modified transmission electron microscopic (TEM) techniques which are providing interesting and valuable insight into the structure of PET film and its changes.Films were prepared by simultaneous biaxial stretching (SBS) of amorphous cast films at 95°C with the rate of 9000 %/min. and draw ratio of 3.5 X. The films were heat-set in die temperature range of 100-240°C. The studies were carried out using three TEM techniques by observation of (a) surface structure by a modified two stage replication method, (b) bulk structure in the film plane by a typical microtomy method, and (c) bulk structure by etching with a mixture of 60% propylamine and 40% water.
Birefringence and Ultrastructure of Isolated, Stabilized Spindles
Authors: LaFountain James R. , Evans Robert L. 
Published: June 2020

Previous investigations on the spindle apparatus in primary spermatocytes of the crane fly, Nephrotoma suturalis, with polarizing optics have shown that chromosomal fibers can be detected as positively birefringent bands extending from the chromosomes to the poles (1). Chromosomal fiber birefringence reaches a maximum at metaphase when five distinct fibers can be seen in each half spindle. An obvious question raised by these results was what is the ultrastructural basis of birefringence?Initial attempts to characterize the ultrastructure of crane-fly spindles showed that there were hundreds of microtubules (MTs) in these spindles, but there was no evidence that they were distributed in a pattern that corresponded to the pattern of birefringence (2,3).
Morphological Alterations of the Blood-Brain Barrier in Experimental Serum Sickness (ESS)
Authors: Donald A. Davis , Thomas H. Milhorat 
Published: June 2020

Information concerning the effects of systemic diseases on the blood-brain barrier is limited. Lampert and Carpenter (1) and Lampert et al. (2) have shown that experimental lead encephalalopathy produces a toxic vasculitis which permits intravascularly injected thorotrast to escape from cerebral capillaries into the perivascular and extracellular spaces. Other experiments (summarized in 3) have demonstrated an increased permeability of cerebral capillaries as a consequence of cerebral trauma, chemically induced vasculitis, hypertension, and radiation.Acute serum sickness was produced in adult male Wistar rats according to the “one shot” technique of Kniker and Cochrane (4). After seven to eight days the animals were decapitated and tissue samples from the cerebral cortex and periventricular white matter were quickly excised and placed in vials for prefixation in 1% depolymerized paraformaldehyde and 31 purified glutaraldehyde in 0.1M phosphate buffer (pH 7.5) for 24 hours at 4C.
Oligodendrocytes in Developing Hameter Cerebral Cortex
Authors: Tank Buschmann MB. 
Published: June 2020

Development of oligodendrocytes in rat corpus callosum was described as a sequential change in cytoplasmic density which progressed from light to medium to dark (1). In rat optic nerve, changes in cytoplasmic density were not observed, but significant changes in morphology occurred just prior to and during myelination (2). In our study, the ultrastructural development of oligodendrocytes was studied in newborn, 5-, 10-, 15-, 20-day and adult frontal cortex of the golden hamster (Mesocricetus auratus).Young and adult hamster brains were perfused with paraformaldehyde-glutaraldehyde in sodium cacodylate buffer at pH 7.3 according to the method of Peters (3). Tissue samples of layer V of the frontal cortex were post-fixed in 2% osmium tetroxide, dehydrated in acetone and embedded in Epon-Araldite resin.
Ultrastructural Features of the Oral Apparatus of Stentor
Authors: Howell Elizabeth F. 
Published: June 2020

The ultrastructure of the normal oral apparatus of Stentor has not been extensively studied. I report here on the ultrastructure of the buccal cavity of Stentor coeruleus.Stentor coeruleus was fixed in either a buffered mixture of osmium tetroxide and glutaraldehyde, or in buffered glutaraldehyde alone. Cells were then dehydrated and embedded in a mixture of Epon and Araldite.An extensive adoral zone of membranelles surrounds the anterior of the cell, and each membranelle consists of 2 parallel rows of cilia. These extend down into the buccal cavity. Two microtubular root fibers, or nemadesmata (Figs. 2 and 5), extend deeply into the cytoplasm from the base of each ciliary kinetosome. Mitochondria are usually closely associated with the root fiber bundles, and small vesicles are present between the nemadesmata of adjacent kinetosomes (Fig. 5). In the cytopharyngeal, non-ciliated areas of the buccal cavity, microtubular ribbons which extend into the cytoplasm are aligned perpendicular to the plasma membrane of the buccal cavity (Figs. 1 and 2).
The Fine Structure of Irradiated Mouse Heart
Authors: Yang Vivian V. , Phyllis Stearner S. 
Published: June 2020

The heart is generally considered a radioresistant organ, and has received relatively little study after total-body irradiation with doses below the acutely lethal range. Some late damage in the irradiated heart has been described at the light microscopic level. However, since the dimensions of many important structures of the blood vessel wall are submicroscopic, investigators have turned to the electron microscope for adequate visualization of histopathological changes. Our studies are designed to evaluate ultrastructural changes in the mouse heart, particularly in the capillaries and muscle fibers, for 18 months after total-body exposure, and to compare the effects of 240 rad fission neutrons and 788 rad 60Co γ-rays.Three animals from each irradiated group and three control mice were sacrificed by ether inhalation at 4 days, and at 1, 3, 6, 12, and 18 months after irradiation. The thorax was opened and the heart was fixed briefly in situwith Karnofsky's fixative.
Cytosomal and Neuronal Changes During Photoreception as Related to Ionic Permeability and Ciliary Activity in Mytilus Epulis
Authors: Murphy Judith A. , Paparo Anthony A. 
Published: June 2020

The lateral ciliated cells in the bivalve, M. edulis are controlled by the nervous system. Ultrastructural studies reveal pigment granules (cytosomes) occurring in the nerve endings under these cells. In response to light, there is a gradual lateral cilioinhibition coupled with a change in morphology of these pigment granules. The purpose of this study was to examine lateral ciliary activity during photoreception as related to both, changes in the pigment granules, and neuronal Ca/K shifts.Gill preparations were isolated and subsequent stroboscopic measurements of lateral cilia were made. Specimens were exposed to light or darkness. The following drugs were added by perfusion: 10-100 mM Ca and 10-6 M ethylene glycol-bis(amino-ethyl-ether)-N,N'-tetraacetic acid (EGTA). Measurements of the orange yellow fluorophore were made on a Leitz MPV system.
Ultrastructural Surface Characterization of Cultured Intracranial Tumors
Authors: Liszczak T. , Jacobson S. , Kornblith P. 
Published: June 2020

One property of a malignant cell is its decreased intercellular adhesiveness in vivo(l), and in vitro(2). In an attempt to visualize any morphological correlates associated with this phenomenon we utilized the replica technique to examine cell surfaces and cell to substrate attachment regions in cultured intracranial tumors, tumors from other sites and reactive cells.Cells were explanted onto glass coverslips in Leighton tubes, cultured to approximately 50%confluency, buffer rinsed, 2.5% glutaraldehyde fixed, chrome-osmium postfixed, critical point dried with Freon 13 and 113, and replicated with platinum carbon. The cells and coverslips were dissolved away by hydroflouric acid.
Acidophil Stem Cell Adenoma of the Human Pituitary: A New Entity
Authors: Horvath E. , Kovacs K. , Ezrin C. 
Published: June 2020

Electron microscopy and immunocytochemistry have been applied to determine the origin of 3 pituitary adenomas found among 70 surgically removed hypophysial tumors, which did not correspond to any tumor type classified so far.The tumors were surgically removed from 3 male patients between 38 - 66 years of age. Clinically, no signs indicative of hormonal hypersecretion were evident. The patients complained of decreased libido and progressing visual disturbances. Blood prolactin levels were markedly elevated in 2 cases, and were normal in one case. Blood growth hormone levels were normal. Additional endocrine laboratory tests failed to provide contributory data.By histology, the tumors corresponded to sparsely granulated acidophilicchromophobic adenomas. The cytoplasm of adenoma cells stained neither with PAS, nor with aniline blue, lead hematoxylin. Negative staining was obtained by various acid dyes, such as eosin, phloxine, orange G or light green, except for occasional granules in a few adenoma cells.
Ultrastructural Change in Muscle Biopsy From a Case of Progressive Ophthalmoplegia
Authors: Dodson R. F. , Patten B. M. , Chu L. W-F. 
Published: June 2020

Progressive external ophthalmoplegia is a disease which is classifiable as a “mitochondrial myopathy” (1). Mitochondrial changes have been reported as giant mitochondria with swirls of cristae, giant mitochondria with paracrystalline structures, and in extreme instances, abnormal mitochondria were reported to be replaced by dense rectangular inclusions and occasionally showed complete transition to crystalline structures (2). Presently we are reporting ultra structural findings from muscle biopsies obtained from a 51 year old man who had been clinically and histochemically diagnosed as having chronic external ophthalmoplegia. Histochemical findings indicate the presence of abnormal mitochondria as a component of the “ragged-red fibers” (3).Specimens from open biopsy of biceps muscle were dissected in a 1 cm long muscle clamp and immediately placed in a 3% glutaraldehyde in 0.1M phosphate buffered fixative.
Tannic Acid as a Mordant for Heavy Metal Stains
Authors: Wagner Roger C. 
Published: June 2020

Tannic acid used concomitantly with glutaraldehyde fixation results in an increase in the electron-density and apparent thickness of the outer leaflet of cell-surface membranes (1,2). This effect has been attributed to binding of tannic acid to cell-surface proteins and subsequent chelation of heavy-metal ions (2). In isolated capillary endothelium (3), the localization and degree of this enhanced density varies according to the point at which cells are treated with tannic acid during fixation and staining and with selective omission of stains and fixativesTreatment of cells with tannic acid(2%) and glutaraldehyde (2%)followed by osmium(l%) and counterstaining of sections (saturated uranyl acetate-10 min., Reynold's lead citrate-3 min.) results in an increase in thickness and electron density of the outer leaflet of all surface membranes including those comprising micropinocytic caveolae (fig. 1). When cells are fixed with glutaraldehyde prior to tannic acid treatment, both inner and outer leaflets of both surface and intracellular membrane systems exhibit an increase in density and apparent thickness (fig. 2).
Modification of Philips Em 301 for Optimum Edx Analysis
Authors: Hren J. J. , Ong P. S. , Johnson P. F. , Jenkins E. J. 
Published: June 2020

It is well recognized that the incorporation of STEM into commercial electron microscopes offers potential advantage for EDX analyses as well. The microscope requirements for high resolution EDX are severe for even qualitative compositional measurements of regions excited by electrons beams approximately 100Ådiameter. We report here on some modifications of a Philips EM 301 equipped with STEM and an Ortec Model 6200 EDX system aimed at improving the EDX capability.Geiss and Huang (1) earlier reported similar studies on metallic alloy films. Our intention is to look at low solute concentrations in both crystalline and amorphous materials, including biological specimens. Thus, we are especially concerned about ultimate sensitivity and resolution for compositional measurements. In turn, these goals dictate special attention to sources of background and secondary excitation.
Micropatterning of Permalloy Films by Electron Lithography
Authors: Maurin J. K. 
Published: June 2020

Conductor, resistor, and dielectric patterns of microelectronic device are usually defined by exposure of a photosensitive material through a mask onto the device with subsequent development of the photoresist and chemical removal of the undesired materials. Standard optical techniques are limited and electron lithography provides several important advantages, including the ability to expose features as small as 1,000 Å, and direct exposure on the wafer with no intermediate mask. This presentation is intended to report how electron lithography was used to define the permalloy patterns which are used to manipulate domains in magnetic bubble memory devices.The electron optical system used in our experiment as shown in Fig. 1 consisted of a high resolution scanning electron microscope, a computer, and a high precision motorized specimen stage. The computer is appropriately interfaced to address the electron beam, control beam exposure, and move the specimen stage.
Inelastic Electron Scattering from Valence Electrons in Aluminum
Authors: Batson P. E. , Chen C. H. , Silcox J. 
Published: June 2020

We wish to report in this paper measurements of the inelastic scattering component due to the collective excitations (plasmons) and single particlehole excitations of the valence electrons in Al. Such scattering contributes to the diffuse electronic scattering seen in electron diffraction patterns and has recently been considered of significance in weak-beam images (see Gai and Howie) . A major problem in the determination of such scattering is the proper correction for multiple scattering. We outline here a procedure which we believe suitably deals with such problems and report the observed single scattering spectrum.In principle, one can use the procedure of Misell and Jones—suitably generalized to three dimensions (qx, qyand #x2206;E)--to derive single scattering profiles. However, such a computation becomes prohibitively large if applied in a brute force fashion since the quasi-elastic scattering (and associated multiple electronic scattering) extends to much larger angles than the multiple electronic scattering on its own.
Accurate Microcrystallography in the S.E.M. using Electron Backscattering Patterns
Authors: Venables J. A. , Harland C. J. , bin-Jaya R. 
Published: June 2020

We have previously shown that electron back-scattering patterns (EBSP) can be observed on a fluorescent screen placed in the specimen chamber of an S.E.M. with the microscope in the spot mode and the angle of incidence > 60°. (1,2). Here we describe methods of determining crystal orientation with 0.5° accuracy using these patterns, and indicate the potential of EBSP's as crystallographic detectors for microscopy at better than 50 nm resolution.The accuracy of orientation determination using an EBSP is limited by the accuracy with which the position of the emitting point on the specimen is known relative to the screen. By casting geometrical shadows of objects onto the screen this position can be determined. Two types of objects have been investigated, a circular mask and three steel balls. The geometry of the mask arrangement is shown in fig. 1, and an EBSP taken using it is shown in fig. 2;an example using the three ball method is shown in fig. 4. During setting up, these patterns were viewed by closed-circuit TV, and then recorded direct onto 35 mm film.
Characterization of a Fixed Beam Electron Microscope with a Field Emission Gun
Authors: Chiu Wah , Glaeser Robert M. 
Published: June 2020

One of the objectives of our research program is to obtain a 2.0 Å point to point resolution in a fixed beam bright field electron microscope. The resolution in the fixed beam electron microscope is limited by a number of factors: electron beam coherence, energy spread, objective lens stability, mechanical stability, and specimen stability. This paper presents systematic studies of the mentioned factors in our JEM 100B fixed beam electron microscope equipped with a field emission gun operating at ∼ 1800°K.The most important characteristic of a field emission gun is its high brightness in the emitter source. In order to estimate the brightness at the specimen plane, one needs to measure the electron beam current density and the angle of illumination. The electron beam current density has been measured by means of a lithium-drifted silicon detector located below the normal position of the photographic plates. The angle of illumination can be estimated from the size of the condenser aperture and its distance from the specimen plane.
An Interactive Minicomputer Program for the Indexing and Simulation of Electron Diffraction Patterns
Authors: Goehner R.P. , Hatfield W.T. , Rao Prakash 
Published: June 2020

Computer programs are now available in various laboratories for the indexing and simulation of transmission electron diffraction patterns. Although these programs address themselves to the solution of various aspects of the indexing and simulation process, the ultimate goal is to perform real time diffraction pattern analysis directly off of the imaging screen of the transmission electron microscope. The program to be described in this paper represents one step prior to real time analysis. It involves the combination of two programs, described in an earlier paper(l), into a single program for use on an interactive basis with a minicomputer. In our case, the minicomputer is an INTERDATA 70 equipped with a Tektronix 4010-1 graphical display terminal and hard copy unit.A simplified flow diagram of the combined program, written in Fortran IV, is shown in Figure 1. It consists of two programs INDEX and TEDP which index and simulate electron diffraction patterns respectively. The user has the option of choosing either the indexing or simulating aspects of the combined program.
Sample Preparation and Measurement of Losses in Electron Optical Analyses of Particulates in Air and Water Samples
Authors: Lee R. J. , DeBray D. R. , Szirmae A. 
Published: June 2020

Electron optical analyses of the type and concentration of particles in air and water samples utilize some method of transferring the particulate material from the collection media to a transmission electron microscope (TEM) grid. The method used represents a significant step in sample preparation and may be the factor limiting the ultimate reliability of the data. We have found that a carbon replication technique in which the collection media (usually a membrane filter) is carbon-coated directly results in no measurable loss during the transfer. The salient features of the technique and a method for direct observation of any losses are described below.Under normal circumstances the sample received at the Electron Microscope laboratory consists of a membrane filter on which particulates have been deposited. This sample, if lightly loaded, may be prepared in the as-received condition.
Multilevel Methods for Following the Evolution of Structure from Ingot to Sheet
Authors: Park B. K. , Fricke W. G. 
Published: June 2020

Most investigations of structure concern themselves with the effect that the final structure in some product has on properties and not on how the structure itself came into being. And yet, the structure of sheet, for example, is profoundly influenced by all steps of fabrication from ingot, through preheat, hot and cold rolling, to final heat treatment. Electronic instruments supplement, or even supplant, the traditional role of the light microscope in following these changes.Taking aluminum auto body sheet alloy X5020 (2.8% Mg, 1.6% Cu, 0.3% Mn, 0.25% Fe, 0.12% Si) as an example, the evolution of final structure was observed with the scanning and transmission electron microscopes, the image analyzing light microscope, x-ray diffraction and the electron microprobe. Particular attention was paid to intermetallics which have a profound influence on formability and ductility.
Limitation of the use of thin Amorphous Carbon Substrates for High Temperature Microscopy
Authors: Lee Eal H. 
Published: June 2020

Carbon films have been used as substrates by many authors at temperatures ranging from 400°-1050°C(1-4). At such high temperatures, however, substrate/ grid interactions become appreciable and the carbon film becomes contaminated, due to carbide formation. Therefore, a series of experiments was performed on the C/Ti, C/Mo, and C/W film/support-grid systems to determine the usefulness of carbon substrates for high temperature TEM applications.Amorphous carbon films approximately 1000 Å in thickness were prepared using conventional arc evaporation and mounted on Ti, Mo, and W grids. The specimens were then placed in a UHV (∼2xl0-8 torr) electron microscope and observed continuously in-situ during their exposure to temperatures greater than 800°C(5). In this study it was found that carbides formed with all specimens after short times of exposure at 900°C. The micrographs in Fig.
Resistance Monitor and Control for Vacuum Evaporation of Metals and Carbon
Authors: Steere Russell L. , Erbe Eric F. , Michael Moseley J. 
Published: June 2020

We have designed and built an electronic device which compares the resistance of a defined area of vacuum evaporated material with a variable resistor. When the two resistances are matched, the device automatically disconnects the primary side of the substrate transformer and stops further evaporation.This approach to controlled evaporation in conjunction with the modified guns and evaporation source permits reliably reproducible multiple Pt shadow films from a single Pt wrapped carbon point source. The reproducibility from consecutive C point sources is also reliable. Furthermore, the device we have developed permits us to select a predetermined resistance so that low contrast high-resolution shadows, heavy high contrast shadows, or any grade in between can be selected at will. The reproducibility and quality of results are demonstrated in Figures 1-4 which represent evaporations at various settings of the variable resistor.