bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a new intelligent EPMA with advanced basic performance
Authors: Kawabe K. , Matsuya M. , Arima H. , Fuktida H. , Tajima H. , Nagatsuka Y. , Saito M. , Nielsen C. H. , Nakagawa S. 
Published: June 2020

A new electron probe mieroanalyzer (EPMA), the JXA-8800, has been developed with improved basic capabilities such as the specimen stage, wavelength dispersive x-ray spectrometers (WDS), and imaging functions. It can be operated easily like automated office equipment and is expandable owing to the use of the latest microelectronics and computer technology.The block diagram of the JXA-8800 is shown in Fig. 1. The control devices for the stage, WDSs, and electron optical system (EOS) are all made intelligent as they are each provided with a built-in microcomputer. Each device is connected to a system controller that manages TARGET, by a high-speed network. The system controller is connected to a host computer by GPIB. A 32-bit engineering workstation (EWS) is used as the host computer and UNIX is used as OS. By utilizing the high-speed graphics function of EWS, the operation of the EPMA can be freely carried out from the graphic display on the EWS color monitor, with the mouse or keyboard.
A two-spring model of the tip-sample interaction using the Scanning Tunneling Microscope in air
Authors: Woodward John T. 
Published: June 2020

The scanning tunneling microscope (STM) is capable of imaging surface features of electrically conductive samples with lateral resolution of 2 Angstroms and vertical resolution of 0.1 Angstroms. This is accomplished by rastering a conducting tip just above the sample surface using a piezoelectric drive. The tunneling current between the tip and the sample, which depends on the distance separating the two, is then used to keep the tip a constant distance above the sample and generate a height plot of the surface.When an STM is used in air, a small liquid bridge can be formed between the scanning tip and the sample as shown in Fig. 1, This bridge results from any fluid contamination on the surfaces along with condensation of primarily water from the air. For most applications of the STM, this liquid bridge has little effect on the image. However if the sample is somewhat flexible or only weakly bound on the STM base, as is the case for freeze fracture replicas, the forces exerted by the liquid bridge on the sample as the tip scans the surface can significantly alter measured heights from their actual values.
Multi-color laser scanning confocal microscopy with a krypton/argon ion laser
Authors: Clark Brelje T. , Sorenson Robert L. 
Published: June 2020

Fluorescence is presently the most important imaging mode in biological confocal microscopy. The optical properties of laser scanning confocal microscopy (LSCM) are particularly favorable for fluorescence microscopy since the generally high signal-to-background ratio is enhanced by LSCM by rejecting out-of-focus fluorescent emissions. In addition, this improved imaging capability along the optical (z-)axis allows the optical sectioning of specimens by adjusting the plane of focus. This removes one of the most severe limitations of convential fluorescence microscopy, the necessity to examine monolayers of cells or thin sections of tissues.However, the advantages of LSCM for multi-color fluorscence microscopy are critically dependent on the availability of suitable light sources and fluorophores. By far the most commonly used light source is a small, air-cooled argon ion laser with emission wavelengths at 488 and 514 nm. Although the most frequently used fluorophores, fluorescein (FITC) and tetramethylrhodamine, can be excited by these wavelengths, it is impossible to specifically excite each fluorophore in the presence of the other fluorophore.
Fulfilling the needs of physical and biological scientists in intermediate and HVEM
Authors: Kersker Michael M. 
Published: June 2020

There are three (therefore 4 or 5) reasons that high voltage microscopes have remained viable tools for applications in both biological and materials science. Higher voltage means higher penetration with lessened effect from image degrading mechanisms, higher resolution due to decreased electron wavelength, and more (or less) damage to structure due to irradiation effects (more) or to decreased ionization cross section (less). Of the 47 high voltage instruments (V > 500kV) installed worldwide, many remain operational for at least one of these three reasons.Few existing instruments are capable of delivering all three advantages. Earlier microscopes were primarily focussed on providing increased penetration and more or less damage since the high voltage stability and objective lens designs were not optimized to provide high resolution imaging as well. Though the past requirements for fulfilling the needs of physical and biological scientists have not changed for now nor are they likely to change in the future, many of the requirements fulfilled by high voltage microscopes are now achievable using lower kV intermediate voltage instruments, and in some cases, even more ubiquitous lower kV ones.
The many faces of STEM in materials science
Authors: Silcox John 
Published: June 2020

Determination of the microstructure and microchemistry of small features often provides the insight needed for the understanding of processes in real materials. In many cases, it is not adequate to use microscopy alone. Microdiffraction and microspectroscopic information such as EELS, X-ray microprobe analysis and Auger spectroscopy can all contribute vital parts of the picture. For a number of reasons, dedicated STEM offers considerable promise as a quantitative instrument. In this paper, we review progress towards effective quantitative use of STEM with illustrations drawn from studies of high Tc superconductors, compound semiconductors and metallization of H-terminated silicon.Intrinsically, STEM is a quantitative instrument. Images are acquired directly by detectors in serial mode which is particularly convenient for digital image acquisition, control and display. The VG HB501A at Cornell has been installed in a particularly stable electromagnetic, vibration and acoustic environment. Care has been paid to achieving UHV conditions (i.e., 10-10 Torr). Finally, it has been interfaced with a VAX 3200 work station by Kirkland. This permits, for example, the acquisition of bright field (or energy loss) images and dark field images simultaneously as quantitative arrays in perfect registration.
TEM in situ straining of polycrystalline stoichiometric NiAl
Authors: Nagpal P. , Baker I. 
Published: June 2020

The purpose of this paper is to present a comparison of the dislocation structures that are present in polycrystalline samples of the B2 (ordered body-centered cubic) compound NiAI after straining in bulk and after in-situ straining of thin foils in the TEM.A dumbell-shaped tensile specimen (gauge length ∼ 10mm; diameter ∼ 3mm) of ∼15μm grain-sized stoichiometric NiAl which had a low initial dislocation density was strained to fracture under tension. The fracture strain was ∼ 2%. Discs were cut from the gauge and thin foils were prepared as described elsewhere. (Processing conditions to obtain this fine-grained material are also described elsewhere.) TEM in-situ straining samples (7mm long; 3 mm wide; 0.25 mm thick, with 1mm diameter loading holes located 1.5mm from the ends, see reference 4 for details) were prepared from the same material and strained in a modified JEOL straining holder. Both sets of samples were viewed in a JEOL 2000FX operated at 200 KeV. For the in-situ experiments images were recorded either on film after a given strain increment or dynamically during straining using a Gatan camera, an image intensifier and a VCR.
RHEED investigation of oxygen-annealed sapphire surfaces
Authors: Liu J. , Cowley J. M. 
Published: June 2020

Reflection high energy electron diffraction (RHEED) has been widely used to study surface reconstructions, surface morphology and crystal growth. In a transmission electron microscope RHEED can be combined with reflection electron microscopy (REM) to study the structures of surfaces with high spatial resolution. In this paper we report some preliminary results of RHEED investigation of the reconstruction of the oxygen annealed sapphire surfaces.The optically polished sapphire samples were obtained from Saphikon Inc. The specimens were cut, cleaned and chemically etched in boiling phosphoric acid before annealing in pure oxygen. Details of the sample preparation procedure was reported elsewhere. Oxygen annealing prevented change of surface stoichiometry and surface reactions with elements other than oxygen. The RHEED experiments were conducted in a Philips 400T transmission electron microscope operated at 120 kV with a vacuum pressure about 10-7 Torr and equipped with cold and hot stages.
Transmission Electron Microscopy of oriented Co84Cr14Ta2 thin films for longitudinal magnetic recording
Authors: Nolan T. P. 
Published: June 2020

Thin film magnetic media are being used as low cost, high density forms of information storage. The development of this technology requires the study, at the sub-micron level, of morphological, crystallographic, and magnetic properties, throughout the depth of the deposited films. As the microstructure becomes increasingly fine, widi grain sizes approaching 100Å, the unique characterization capabilities of transmission electron microscopy (TEM) have become indispensable to the analysis of such thin film magnetic media.Films were deposited at 225°C, on two NiP plated Al substrates, one polished, and one circumferentially textured with a mean roughness of 55Å. Three layers, a 750Å chromium underlayer, a 600Å layer of magnetic alloy of composition Co84Cr14Ta2, and a 300Å amorphous carbon overcoat were then sputter deposited using a dc magnetron system at a power of 1kW, in a chamber evacuated below 10-6 torr and filled to 12μm Ar pressure. The textured medium is presently used in industry owing to its high coercivity, Hc, and relatively low noise. One important feature is that the coercivity in the circumferential read/write direction is significandy higher than that in the radial direction.
Microstructural characterization of CoPtCr/Cr thin film disks by cross-section TEM and elongated probe micro-diffraction
Authors: Parker M.A. , Johnson K.E. , Hwang C. , Bermea A. 
Published: June 2020

We have reported the dependence of the magnetic and recording properties of CoPtCr recording media on the thickness of the Cr underlayer. It was inferred from XRD data that grain-to-grain epitaxy of the Cr with the CoPtCr was responsible for the interaction observed between these layers. However, no cross-sectional TEM (XTEM) work was performed to confirm this inference. In this paper, we report the application of new techniques for preparing XTEM specimens from actual magnetic recording disks, and for layer-by-layer micro-diffraction with an electron probe elongated parallel to the surface of the deposited structure which elucidate the effect of the crystallographic structure of the Cr on that of the CoPtCr.XTEM specimens were prepared from magnetic recording disks by modifying a technique used to prepare semiconductor specimens. After 3mm disks were prepared per the standard XTEM procedure, these disks were then lapped using a tripod polishing device. A grid with a single 1mmx2mm hole was then glued with M-bond 610 to the polished side of the disk.
Profile TEM observations of small UHV-grown palladium particles
Authors: Neiman D.L. , Fuchs G. , Poppa H.R. 
Published: June 2020

Projectional Transmission Electron Microscopy (TEM) of vapor-grown metal clusters on oxide supports is an extensively-used technique. An important limitation to this technique is the difficulty in determining the particle shape parallel to the electron beam. Use of submicron-sized “micro-supports” such as microcubes (MgO) and microspheres (TiO2 and Al2O3) allows the metal particles to be seen directly in profile. This has been shown for nonreactive deposits such Au, but few results for reactive metals have been published (notably Pd/MgO2 and Rh/TiO2). We present results for the system Pd/Al2O3, which show limitations to the use of profile TEM in the study of reactive metal deposits.Plasma-grown microspheres of A12O3 were supended in cthanol and then applied to commercial holey carbon grids. The grid were inserted into an ultrahigh vacuum (p<2x10-7 Pa) system for Pd deposition. Palladium was deposited from a heated-wire source at a rate R = 0.03nm/min. Sample temperature during deposition was 573K.
Silver staining of fluorocarbon copolymer membranes for contrast enhancement
Authors: Garrison C.C. , Garcia-Meitin E.I. 
Published: June 2020

Fluorocarbon copolymer membranes will replace conventional diaphragms in new generation chlorine cell designs. One design of such membranes is a bilayer material consisting of barrier (carboxylic) and support (sulfonic) layers which allow transport of sodium ions and inhibit transfer of other species. While the two layers can be distinguished without staining in the transmission electron microscope (TEM), resolution at the interface is typically 50 nanometers. Resolution can be improved to 5 nanometers after staining the membranes with silver ions.Previous work on staining sulfonic copolymers has been published. Xue et al. obtained excellent staining with vapor phase ruthenium tetraoxide. However, our lab was unsuccessful in applying this technique in the current study. Chryssikos et al. obtained good results using silver ions to stain by ion exchange. Since the membrane is designed to transport sodium ions, similarities between silver ions and sodium ions (+1 charge, similar ionic radii) point toward silver as a good choice. Staining experiments were carried out using silver ions, zinc ions, and ruthenium tetraoxide vapor.
Microstructural improvements in melt-textured YBa2Cu3O7 bulk superconductors
Authors: Sabatini R.L. , Zhu Yimei , Wang Y.L. , Suenaga Masaki 
Published: June 2020

In spite of its known high intragranular current density Jc, bulk YBa2Cu3O7(123) superconductors presently have a limited commercial viability due to their low current carrying capacities. Thus the problem with the bulk superconductors is widely attributed to its weak coupling at the grain boundaries. One possible solution, based on work by Jin and others, is to “melt texture” the sample so that grains align to provide a high current path through the material. But melt texturing produces other problems such as microcracking and shape distortion.To investigate the problems associated with producing high Jc bulk superconductors from the melt texturing process, we have studied the effects of modifying composition and processing conditions of the samples and examined the resulting microstructure and electrical properties.
Possible flux pinning centers in YBa2Cu3O7-x
Authors: Kulik J. , Huang Z.J. , Bechtold J. , Xue Y.Y. , Hor P.H. 
Published: June 2020

The critical current density Jc of a superconductor is one of its most important properties for the purposes of applications. Various investigators have made numerous attempts to increase the value of Jc in the high temperature superconductor YBa2Cu3O7-x (Y123) through the introduction of defects into the crystal structure. References 1, 2, and 3 provide a few examples of some of the more recent efforts. In general, defects of an appropriate size should act as flux pinning centers in the material.We have attempted to increase Jc in Y123 samples both through bulk processing techniques and through irradiation by fast neutrons. In an attempt to correlate the microstructures of the materials with the superconducting properties we have studied the materials using TEM. Here, we report on results from two samples. The first is an Y123 sample prepared by the decomposition of YBa2Cu4O8 (Y124). The decomposition process results in Y123 material with a value of Jc which is enhanced by approximately a factor of 10 at low magnetic field at 77 K as compared with Y123 prepared by standard processes. The second sample is one which was irradiated with fast neutrons (> 0.1 MeV) to a fluence of 6.0 x 1017 cm-2. This sample also shows an increase in Jc.
Mechanism for radiation damage in borosilicate glasses
Authors: Dascomb S.D. , Howitt D.G. 
Published: June 2020

Oxygen bubble formation has been observed in sodasilicate glasses during irradiation. Although the irradiation always produces a consistent microstructure of oxygen microbubbles and an amorphous phase decomposition, there is a substantial difference between the rate at which the damage occurs. When a sample has been previously gamma irradiated, the damage occurs at much greater rates when compared to in situ irradiation in the electron microscope. It has been suggested that it is not the radiation damage rate that is responsible for this behavior but rather the presence of an electric fieldFigure 1 illustrates the microstructure found in a sodasilicate glasses showing the characteristic bubble formation on the perimeter of the area illuminated by the beam and the phase separation within the interior.
The Structural Basis of Synaptic Transmitter Release
Authors: Pfenninger Karl H. 
Published: June 2020

For intercellular transfer of signals, neurons form long processes to contact and form junctions with selected target cells or specific parts thereof. At these sites, they release in a quantal fashion neurotransmitter substances which interact with the receptors of the target cells. Thus, synaptic ultrastructure bears the characteristics of a secreting cellular region combined with those of a junctional complex.Synaptic junctional structure consists of a set of cytoplasmic and cleft (i.e., extracellular) elements which are formed by proteinaceous and (in the cleft) carbohydrate-bearing components anchored in the joined plasma membranes. The synaptic cleft is filled with two layers of material that can be stained with cytochemical techniques such as ethanolic phosphotungstic acid (E-PTA) and bismuth-iodide (BIUL; for review, see 1).
The Influence of Antifertility Agents on the Fine Structure of the Male Reproductive Tract
Authors: Flickinger Charles J. 
Published: June 2020

The effects of antifertility agents on the histology and fine structure of the male reproductive tract have been studied, with the objective of understanding the basis of the antifertility action. Certain agents were chosen for study as representatives of classes of compounds that affect the reproductive tract by different mechanisms. These include: 1) a progestin and progestin plus androgen, which are steroids that suppress gonadotropin release; and 2) cyproterone acetate, a representative of the antiandrogens, which are compounds that interfere with the action of testosterone on target cells.The combination of a progestin and androgen is currently believed to show promise as a male contraceptive. The progestin is thought to reduce gonadotropin secretion and suppress spermatogenesis. However, the Leydig cells of the testis are also suppressed and their secretion of testosterone is diminished.
Structure of the “Core” Particles from 50S IS. coli Ribosomes Depleted by LiCl.
Authors: Spiess E. , Roth H.E. , Hellmann W. , Jenkins F. , Boublik M. 
Published: June 2020

Involvement of ribosomes in protein synthesis is well established. Also substantial data about the roles of both ribosomal constituents, proteins and ribonucleic acids, in this process are known. However, the detailed mechanism of the function of ribosomes remains obscure, mainly because of our limited knowledge of the interactions and structural arrangement of ribosomal components.One of the approaches to study ribosome structure involves progressive depletion of proteins and correlation of the protein-depleted ribonucleoprotein cores with function. High resolution electron microscopy has been applied for direct imaging of the changes in the fine structure of depleted ribosomes.
Acridine Orange Staining Reaction in Bone Marrow Colony Forming Units Incubated with Phytohaemagglutinin
Authors: Ahearn M. J. , Trujillo J. M. , Dicke K. A. 
Published: June 2020

It has recently been demonstrated that bone marrow cells from acute leukemia patients in active disease will form colonies in vitro in soft agar if pre-incubated in phytohaemagglutinin (PHA). This finding is contrary to evidence obtained from the Robinson System of in vitro culture utilizing a leucocyte stimulating factor to promote significant colonies of marrow cells only from haematologically normal individuals.In the present investigation the effects of the PHA incubation on human bone marrow cells from leukemia patients in the acute and remission phases of their disease, as well as normal controls, are studied utilizing Frenster's acridine orange reaction product to delineate the active extended euchromatic portion of the cell nucleus.
Fine Structure of Rat Extraocular Muscle in Myotonia Induced by 20,25- Diazacholesterol
Authors: Pachter Bruce R. , Davidowitz Jacob , Breinin Goodwin M. 
Published: June 2020

Rats administered with 20,25-diazacholesterol manifest physiological and clinical signs characteristic of human myotonic dystrophy, i.e., prolonged contraction and bizarre electromyographic discharges which are not abolished by curare or peripheral nerve block, in association with prominent ptosis, cataract formation and testicular atrophy. The extraocular muscles (EOM) are prominently involved in human myotonic dystrophy but have not been studied on the electronmicroscopic (EM) level; the present study examined the EOM of rats with induced myotonia as a possibly suitable model of the human syndrome.Wistar rats (125 gms.) were injected with 13mgAg of 20,25-diazacholesterol, daily for 2-3 weeks. These animals were perfused with 1% paraformaldehyde- 1% glutaraldehyde. The superior rectus muscle was dissected free and prepared by standard EM procedures, embedded whole in Epon 812 and serially sectioned at 15 microns.
The Application of Quantitative Stereology to the Study of Adenohypophyseal Cells
Authors: Poole Max C. , Mahesh V.B. , Costoff Allen 
Published: June 2020

Quantitative stereology of liver parenchymal cells has previously been reported (1,2), but there have been few studies of morphometry applied to a heterogenous tissue (3). Due to the presence of several different cell types, it is difficult to study the synthesis and secretion of hormones in cells of the anterior pituitary by conventional biochemical means. In this study prolactin cells were analyzed using morphometry during different times of the rat estrous cycle, and were correlated with changing levels of prolactin in the serum and pituitary gland.Vaginal smears of 60 day old Holtzman rats were monitored through three estrous cycles, and only four day cycling rats were used. Groups of six animals were decapitated at 4 P.M., 6 P.M., 10 P.M. and 12 midnight of proestrus and one half of the pituitary was processed for electron microscopy and the other half for assay.
Aspects of Endocytosis in the Ciliate Tetrahymena Pyriformis
Authors: L. J. Brenner  , D. G. Osborne  , B. L. Schumaker  
Published: June 2020

The ciliate, Tetrahymena pyriformis, is an excellent cell for studying endocytic processes. It ingests particulate matter like bacteria and latex particles by way of the buccal apparatus. Soluble material entering by pinocytosis and the coalescing of pinocytic vacuoles to form larger vesicles also occurs. It is not uncommon to see autophagic vacuoles containing recognizable cytoplasmic structures like mitochondria. The visualization of the formation of a food vacuole in the cytopharyngeal region has not been accomplished. Some observations reported in this paper may cast additional light on this and other endocytic processes.Static cultures of log phase cells of strain WH6 were generally used. Most of the preparations studied were of control animals suspended in dilute NaCl solution. Chance bacterial contaminants frequently served as valuable reference points.