bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructural features of human pituitary adenomas producing growth hormone, prolactin and thyrotrophin
Authors: Horvath E. , Kovacs K. , Scheithauer B. W. 
Published: June 2020

The majority of pituitary adenomas are monohormonal and monomorphous, i.e. they produce only one hormone and are composed of one morphologic cell type. About 12-15% of pituitary adenomas are piurihormonal containing more than one hormone, either in one cell type (monomorphous) or 2 or more morphologic types (plurimorphous). Most piurihormonal adenomas produce growth hormone and prolactin. Other combinations are uncommon.We report here the ul trastructural features of 11 pituitary tumors which produced growth hormone (GH), prolactin (PRL) and thyrotrophin (TSH), as shown by immunohistochemistry. They were removed by surgery from 3 men and 8 women between 24 and 63 years of age. Eight tumors were associated with elevated blood GH levels and acromegaly. In 3 patients, blood prolactin levels were elevated. Hyperthyroidism was evident in 1 woman with elevated blood TSH levels.For fine structural studies, parts of tissue were fixed in 2.5% glutaraldehyde, postosmicated in 1% OsO4, dehydrated in graded ethanol, processed through propylene oxide and embedded in an Epon-Araldite mixture. Ultrathin sections were stained with uranyl acetate and lead citrate and investigated with a Philips 300 electron microscope.
Zoospores were produced by gill rot pathogen
Authors: Liu Kuo-chun , Chien Chau-heng 
Published: June 2020

Branchiomycosis of fish is commonly known as gill rot which was first reported in Germany more than seventy years ago. In recent years world-wide occurrence was observed among cultured fish species. The causal agent of this disease was a low form of fungus in the genus of Branchiomyces. Two species, B. demigrans and B. sanguinis, were identified mainly according to their morphological differences such as the thickness of the hyphae and the diameters of the spores.Available literature indicated that the shape of the spores was round and the size of the spores was 5 to 9 μ in B. sanguinis and 12 to 17 μ in B. demigrans. Recently, Egusa and Ohiwa reported similar observation from diseased samples of eel Anguilla japonica cultured in Japan. They also reported that no flagellum was observed in fixed samples. Chien et al., indicated that the spores produced by the pathogen were endospores.
Historical Introduction
Authors: Heidenreich R. D. 
Published: June 2020

This program has been organized by the EMSA to commensurate the 50th anniversary of the experimental verification of the wave nature of the electron. Davisson and Germer in the U.S. and Thomson and Reid in Britian accomplished this at about the same time. Their findings were published in Nature in 1927 by mutual agreement since their independent efforts had led to the same conclusion at about the same time. In 1937 Davisson and Thomson shared the Nobel Prize in physics for demonstrating the wave nature of the electron deduced in 1924 by Louis de Broglie.The Davisson experiments (1921-1927) were concerned with the angular distribution of secondary electron emission from nickel surfaces produced by 150 volt primary electrons. The motivation was the effect of secondary emission on the characteristics of vacuum tubes but significant deviations from the results expected for a corpuscular electron led to a diffraction interpretation suggested by Elasser in 1925.
TEM Evidence for the Ejection of Matter by Energetic Displacement Cascades
Authors: Merkle K.L. 
Published: June 2020

At the first wall of a D-T fusion reactor very energetic displacement cascades will be produced. These cascades are initiated by 14 MeV neutron recoils of energies near 100 keV and above. Such cascades can also be produced by selfion bombardment. TEM has served in the past as a valuable tool in investigations of cascade defect structures; also quantitative correlations between cascades produced by energetic self ions and 14 MeV neutrons have been established.1 Qualitatively Figs. 1 and 2 show strong similarities between 200 keV self ion cascades and cascades produced by 14 MeV neutron bombardment of Au. Most clusters visible in Fig. 1 and 2 are thought to result from the collapse of depleted zones. The presence of multiple defect clusters is indicative of subcascade formation.The intersection of an energetic cascade with a surface will lead to the ejection of atoms or clusters of atoms. This problem of surface erosion has recently found considerable attention.
In-Reactor Precipitation of Gamma Prime in Nimonic PE16
Authors: Gelles D. S. 
Published: June 2020

Iron-based precipitation hardened superalloys are being considered for use as structural materials in Fast Breeder Reactors due to their high temperature strength. Appropriate application of these materials requires an understanding of the microstructural stability of precipitation hardening phases in the radiation damage environment. It is not yet clear whether irradiation will affect precipitate stability in-reactor; a whole host of possible behaviors have thus far been considered (1). Transmission electron microscopy appears to be the technique best suited for evaluating precipitate stability. Precipitate sizes in these alloys range from a few atom diameters to several microns, well within the range of state-of-the-art electron microscopy techniques.An example of the complexity of reactor-induced gamma prime precipitation for these materials is provided in Fig. 1. Nimonic PE16 (Fe-44Ni-15Cr-lAl-lTi-3Mo) is a precipitation hardened commercial alloy containing aluminum and titanium additions in order to develop the coherent gamma prime phase for improved strength.
High Resolution Electron Microscope Using a New 200 kV Electron Gun
Authors: Kamimura S. , Katsuta T. , Minamikawa Y. 
Published: June 2020

Higher accelerating voltage has been required of transmission electron microscopes in various research and application fields. In this report, a new electron gun developed by Hitachi, Ltd. will be described. The aim of this development was to design a compact 200 kV electron microscope offering simplicity and convenience of operation and maintenance and the highest possible performance.Description will be made first on the packaged electron gun. Fig. 1 shows the sectional view of the gun. The accelerating tube is built in the gun housing so as to be free from exterior impact. Unlike the conventional gun housing, this one is made of epoxy resin instead of metal. The inside diameter of the housing is reduced to 170 mm due to the excellent insulation property of epoxy resin. A bushing for high voltage cable is mounted on the housing, making its withstand voltage high in spite of the short contour of the housing (140 mm).
A Simple Airlock Gold Coater and Technique for Coating Heat Sensitive Samples
Authors: Allard L.F. , Thomas P.D. , Bigelow W.C. , Kirchoff B.K. 
Published: June 2020

In our laboratory, we frequently observe delicate biological samples in the SEM using cold stage and micromanipulation techniques. The accumulation of static charges often occurs on frozen tissue samples, and on critical point dried samples which are being microdissected “in situ”, thereby causing degradation of the image. In such instances it is useful to be able to coat a sample with gold to eliminate charging without warming it or exposing it to the atmosphere. We have developed a simple airlock coater for the JEOL JSM-U3 SEM, which permits a frozen specimen to be coated without introducing surface artifacts which result from moisture condensation or heating during coating. The entire system can be constructed for about $500.00. Detailed drawings and circuit diagrams are available from the authors upon request.Figure 1 shows an overall view of the airlock coating chamber attached to the SEM airlock. This chamber has an insulated copper rod feedthrough which is attached to a sample stage.
The New ANL Materials Science HVEM Facility
Authors: Lyles R. L. , Merkle K. L. , Okamoto P. 
Published: June 2020

A new transmission HVEM facility has been completed at Argonne National Laboratory. The ANL HVEM provides the beginning of a dedicated materials research laboratory which will subsequently include an interface with a 2 MV tandem accelerator and a low energy ion injector for iri situ ion irradiation and ion beam analysis experiments (Figure 1).The microscope, an improved version of the AEI EM-7, has an accelerating voltage of 1.2 MeV. Moreover, a number of exceptional features have been designed into the instrument which will significantly enhance its usefulness in materials research: 1. High vacuum specimen chamber with direct ion pumping. 2. Instrumentation for two independent and alternatively selectable dark field conditions. 3. Negative ion trap. 4. Ion beam interface. In addition, a helium temperature, side entry, cooling stage is being developed at ANL . The negative ion trap and the ion beam interface are features that have not been previously included in HVEM designs.
Lattice Imaging of a High-Angle Grain Boundary in Germanium at 500kv
Authors: Krivanek O.L. , Isoda S. , Kobayashi K. 
Published: June 2020

The promise of the new generation of high-voltage, high-resolution electron microscopes (HREMs) for atomic resolution studies in materials science has excited considerable interest (1). This paper describes an application to elemental Ge of the first member of this generation, the Kyoto 500kV HREM (2).Fig. 1 shows a (Oil) Ge crystal almost certainly less than 100Å thick, supported by a thin amorphous Ge film and surrounded by several Au crystallites. The specimen was prepared by vapor co-deposition of Au and Ge from separate sources onto a rock salt substrate held at room temperature. The imaging parameters were: accelerating voltage 500kV, axial illumination, no objective aperture, el. opt. mag. 200 000x, exposureotime 10 secs and, as the optical diffractogram (Fig. lb) shows, defocus =-600Å (≃ Scherzer defocus). The dashed circles in the diffractogram show the theoretical extent of the first phase-contrast transfer interval. The interval easily includes all the 111 diffraction spots, indicating that all the end-on (ill) planes and the defects they contain have been imaged faithfully and without distortion.
Experiments With Thin Single Crystal Graphite Films
Authors: Mlinarsky L. 
Published: June 2020

The ability to make extremely thin single crystal films could be potentially of great use for high resolution biological and single atom electron microscopy because the substrate noise could be greatly reduced over that obtained with amorphous films. (That is, the number of atoms in any resolution cylinder would not obey a Poisson distribution but would vary in a regular fashion.) This would increase the visibility of atoms and biological particles and would permit imaging with less dose. In addition, very thin films would be useful in minimizing multiple scattering effects in electron energy loss spectra which would be helpful in interpreting EXAFS-like structure near inner shell excitation edges. For these reasons, we have started a program aimed at trying to fabricate very thin (∽20-30 Å) single crystal films.We have begun to grow thin graphite films after the method of Riddle and Siegel (1).
Calculation Of Stem Dark-Field Images
Authors: Fertig J. , Rose H. 
Published: June 2020

Dark-field imaging is a promising procedure to visualize single atoms in high resolution electron microscopy. The quality of a dark-field micrograph depends to a large extent on the illumination mode for the CTEM or on the detector geometry for the STEM. The most commonly used dark-field modes are: CTEM with axial, tilted, or hollow-cone illumination and STEM with an annular detector limited by the angles and θ1-θ2. The STEM is equivalent to a CTEM which uses hollow-cone illumination of finite angular width (limiting angles θ1, θ2). the following we always assume θ2 = п/2.The three CTEM imaging modes have been investigated theoretically by several authors. Krakow (1) computed dark-field images of small organometallic molecules assuming tilted illumination. However, he could not achieve results for hollow-cone illumination because his computing method was too timeconsuming. Hoch (2) calculated images of model objects under axialy tilted, and hollow-cone illumination of infinitely small angular widthy applying the fast Fourier transform technique.
Quantitative Analysis of Human Gastric Parietal Cells
Authors: Turner J. N. , Chey W.Y. 
Published: June 2020

Stereologic analysis has been performed on the images of parietal cells from the body of the stomach from eleven patients--five with Zollinger-Ellison Syndrome (Z-E), three with gastric ulcer (GU), and three with esophagitis who serve as controls (C). Two blocks were randomly selected from each patient for sectioning. All parietal cells in both block faces were photographed and five cells were randomly selected from the photographs from each block (i.e. 10 cells per patient).Cell diameters were measured both parallel to and perpendicular to the basement menbrane. Figure 1 is a bar plot showing the means and standard deviations for these measurements. There was no statistical difference between the three groups for the measurement parallel to the basement membrane. However, the mean perpendicular diameter of the cells (19.0 μm) from the Z-E cases was greater than that (15.8 μm) of the control group (p<0.05).
Subcellular Localization of Fluorinated Serotonin in Human Platelets by Electron Energy-Loss Spectroscopy
Authors: Costa J.L. , Joy D.C. , Maher D.M. , Kirk K.L. , Hui S.W. 
Published: June 2020

Fluorinated organic molecules have considerable potential as tracers in bio logical systems, since a number of fluorinated analogs demonstrate biological activity similar to that of the parent molecule1. To date, however, the subcellular localization of fluorine has been hampered by the relatively low sensitivity of conventional X-ray microanalysis systems to fluorine. Electron energy-loss spectroscopy, in contrast, is a very efficient method for detecting light elements. We have capitalized on the high sensitivity of this technique to fluorine to identify and localize fluorinated serotonin at a subcellular level in human platelets.Intact human platelets were incubated with 10-5 M concentrations of either serotonin (5HT) or 4,6 difluoroserotonin (DF5HT)2 for 30 minutes at 37°C. Following the incubation period, air-dried whole mounts3 were prepared on 200 mesh copper grids coated with collodion and carbon. Individual platelets were examined at 80 kv in the STEM mode (10 nm spot size), utilizing a Jeol 100B microscope equipped with a field emission gun, a scanning attachment, an electron spectrometer, and a Kevex analysis recording system.
Quantitative Metallurgical Applications of Plasmon Energy Loss Microanalysis
Authors: Williams David B. 
Published: June 2020

When A1 and Mg alloys are studied in the transmission electron microscope, the principal energy loss sustained by the 100 kV imaging electrons that of plasmon excitation (quantized oscillations of the free electrons). ! By placing an electron spectrometer beneath the viewing screen of the micro scope, with a limiting entrance slit, the energy loss spectrum from a line ' the bright field image may be obtained, see Fig. 1. The spectrum consists a zero loss line and plasmon loss lines corresponding to one or more plasmo excitations. It has been shown that the spectral peak position may be reladirectly to composition with an accuracy of < 1wt%)(1) and a spatial resolution of < 10nm.(2) Thus changes in peak separation across the spectrum may interpreted in terms of composition changes along a line in the image.By placing the spectrometer entrance slit underneath a grain boundary, the solute composition profiles accompanying grain boundary precipitation have been investigated.
Transmission Electron Microscopy Studies of Ti-6A1-4V Showing the Microstructural Influence on Fatigue Life and Microhardness Values
Authors: Imam M. Ashraf 
Published: June 2020

The purpose of this paper is to discuss the improvement of some material properties through changing the microstructure. Transmission electron microscopy TEM, has been used to characterize microstructures of the Ti-6A1-4V alloy after different heat treatments. These microstructural studies have been correlated with fatigue property measurements and microhardness values as shown in Table 1. In general, microhardness increases with increasing solution treatment temperature while fatigue resistance reaches a maximum at 900°C and then again decreases.Experimentally, the ELI Ti-6A1-4V specimens were heat treated under the conditions shown in Table 1. Surfaces were polished to a 16 μm surface prior to fatigue testing at ±0.020 shear strain with a constant axial stress of 2.12 x 107 N/M2. Thin foils for TEM observation at 100KV and 200KV were obtained by spark cutting followed by electropolishing in a solution of 62.5% methanol, 31% butanol and 6.5% of 70% perchloric acid at 13.9 volts at -40°C.
Cementation of Copper on Pure Aluminum: Analysis of the Two-Step Rate Mechanism by Scanning Electron Microscopy
Authors: Annamalai V. 
Published: June 2020

Iron has been the major source of the precipitant metal in the copper cementation process. Aluminum, due to its abundant availability in the form of beverage cans, has been used successfully in the process in laboratory experiments1. In a recent study of the cementation of the Cu2+/pure A1 system2, it was found that the reaction rates followed a distinct two-step rate mechanism. This paper presents a physical explanation of the two-step rate mechanism on the basis of the structural characteristics of the copper deposits.A specially designed cementation cell along with aluminum (99.99% pure) rotating discs was used in this study2. Ultrasonic experiments were conducted using an 80 watt Bransonic 12 ultrasonic cleaner. Copper deposits were examined in a Hitachi Perkin-Elmer HHS-2R scanning electron microscope operated at 25 KV in the secondary electron emission mode.In most of the experiments, two distinct kinetic regions were observed, namely an initial slow rate followed by a final enhanced rate.
a<100> Dislocation Loops in MgO
Authors: Narayan J. , Ohr S. M. 
Published: June 2020

Dislocation loops having a/2 <110> Burgers vectors on {110} planes introduced by plastic deformation and subsequent annealing of MgO have been studied extensively in the past using transmission electron microscopy.1 Recently it was reported that high temperature electrical conduction for a long period of time (> 100 hours) induced a thermal breakdown2 in MgO crystals. Transmission electron microscope investigation of these samples just before the thermal breakdown, revealed the presence of a type of loop not previously observed in this material with a<100> Burgers vector lying in {100} planes.Figure la-d shows electron micrograph of two of these a<100> type loops for diffraction vectors (ḡ) [200], [020], [220] and [220], These micrographs were taken under kinematical diffraction conditions with the deviation parameter w ∽ 1.0. From stereo microscopy it was determined that the loops labeled α and β lie on (001) and (100) planes respectively.
SEM Study of Tension Wood Fiber Morphology and its Effect on Paper Properties
Authors: Robinson K. W. 
Published: June 2020

Tension wood (TW) is an abnormal tissue of hardwood trees; although it has been isolated from most parts of the tree, it is frequently found on the upper side of branches and leaning stems. TW has been classically associated with geotropic alignment, but more recently it has been associated with fast growth. Paper made from TW is generally lower in strength properties. Consequently, the paper industries' growing dependence on fast growing, short- rotation trees will result in higher amounts of TW in the final product and a corresponding reduction in strength.Relatively few studies have dealt with the role of TW in the structure of paper. It was suggested that the lower strength properties of TW were due to a combination of factors, namely, its unique morphology, compression failures in the cell wall, and lower hemicellulose content. Central to the unique morphology of the TW fiber is the thick gelatinous layer (G-layer) composed almost entirely of pure cellulose.
A Freeze Shadow Technique for the Preparation of Soft Paint Latexes for Electron Microscopy
Authors: Walter Earl R. , Bryant Glen H. 
Published: June 2020

With the development of soft, film forming latexes for use in paints and other coatings applications, it became desirable to develop new methods of sample preparation for latex particle size distribution studies with the electron microscope. Conventional latex sample preparation techniques were inadequate due to the pronounced tendency of these new soft latex particles to distort, flatten and fuse on the substrate when they dried. In order to avoid these complications and obtain electron micrographs of undistorted latex particles of soft resins, a freeze-dry, cold shadowing technique was developed. The method has now been used in our laboratory on a routine basis for several years.The cold shadowing is done in a specially constructed vacuum system, having a conventional mechanical fore pump and oil diffusion pump supplying vacuum. The system incorporates bellows type high vacuum valves to permit a prepump cycle and opening of the shadowing chamber without shutting down the oil diffusion pump. A baffeled sorption trap isolates the shadowing chamber from the pumps.
Studies of Oxide Formation on Copper Thin Films by Electron Microscopy
Authors: Hembree G. G. , Otooni M. A. , Cowley J. M. 
Published: June 2020

The formation of oxide structures on single crystal films of metals has been investigated using the REMEDIE system (for Reflection Electron Microscopy and Electron Diffraction at Intermediate Energies) (1). Using this instrument scanning images can be obtained with a 5 to 15keV incident electron beam by collecting either secondary or diffracted electrons from the crystal surface (2). It is particularly suited to studies of the present sort where the surface reactions are strongly related to surface morphology and crystal defects and the growth of reaction products is inhomogeneous and not adequately described in terms of a single parameter. Observation of the samples has also been made by reflection electron diffraction, reflection electron microscopy and replication techniques in a JEM-100B electron microscope.A thin single crystal film of copper, epitaxially grown on NaCl of (100) orientation, was repositioned on a large copper single crystal of (111) orientation.
Limitations and Prospects of Freeze-Fixation and Freeze-Etching
Authors: Moor Hans 
Published: June 2020

Ever since the freeze-etching method became a routine laboratory technique, an increasing number of scientists has applied it in biological and especially in membrane research. The manifold details of membrane architecture gave rise to a multitude of questions as to the functional significance of these structures, the possible introduction of artificial alterations and the presumptive limits of the method.The limitations of freezing originate from segregation phenomena in the cytosol caused by rapidly growing ice crystals. Using the standard freezing technique (dipping specimens in liquid Freon or propane) segregation artifacts are avoided by the application of antifreeze agents. Mani structures are stable or can be stabilized against the action of the antifreeze. If this is not possible, very high freezing rates have to be achieved. These require special techniques using a propane jet or a jet of liquid nitrogen under high hydrostatic pressure (1).