bluuebunny/crossref_metadata_2025 huggingface dataset:
On the use of human autoantibodies in the determination of cytoskeletal-cell surface interactions
Authors: Goldman Robert D. , Jones Jonathan C. R.
Published: June 2020

Intermediate filaments (IF) form a cytoskeletal system which appears to connect the nuclear surface with the cell surface. At the level of the nuclear surface, IF appear to be anchored to the outer nuclear envelope membrane and/or to nuclear pore complexes. In turn, these cytoplasmic IF are also thought to be linked in some unknown fashion to the nuclear lamina which is composed primarily of a polymer of the Type V IF proteins, the nuclear lamins. At the level of the cell surface, IF are connected to plasma membrane associated structures at sites of cell-cell and cellsubstrate adhesion. In epithelial cells, adhesion sites between cells include desmosomes and the major adhesion sites between basal cell surfaces and the basement membrane are termed hemidesmosomes.
Ultrastructural identification of Toxoplasma gondii in the acquired immunodeficiency syndrome
Authors: Price George , Pearl Gary , Cerezo Lizardo
Published: June 2020

With the onset of the Acquired Immunodeficiency Syndrome (AIDS), a variety of opportunistic infections have now become prevalent as a complication of the Human Immunodeficiency Virus (HIV). These infections may be viral, bacterial, fungal, or protozoal.

Toxoplasma gondii is a protozoan that can infect humans in parasitic symbiosis. In the past, toxoplasmosis was most commonly found as a congenital infection of neonates, but has become a prominent infection of patients with AIDS. The cystic stage of the organism may be found in the central nervous system, skeletal muscle, cardiac muscle, and visceral organs. The tachyzoites, or individual organisms, are found in a variety of tissues, cells, and body fluids. The route of infection is either by ingestion of the organism from material contaminated by feline feces, or from the ingestion of the coccidian oocysts from the meat of infected animals.
Eukaryotic genome organization analyzed by electron microscope in situ hybridization
Authors: Hamkalo Barbara A. , Narayanswami Sandya , Dvorkin Nadja
Published: June 2020

In situ hybridization is a powerful tool for the localization of DNA/RNA sequences in nuclei and chromosomes. The introduction of nonisotopic labelling methodologies in conjunction with fluorescent or enzyme-linked detection have resulted in a dramatic increase in the application of this technique at the light microscope (LM) level and has placed it in a pivotal role in cell biology, development and genetics. Development of equivalent mapping protocols at the EM level offers increased spatial resolution. We have combined the use of nonisotopic probes with invmunogold labelling to investigate eukaryotic genome organization at high resolution.

Metaphase chromosomes released from mitotically-arrested cells are deposited on gold EM grids by centrifugation through a sucrose cushion. After fixation (0.1% glutaraldehyde, 20 min) and DNA denaturation, chromosomes are hybridized to cloned probes enzymatically labelled with biotin-dUTP, digoxigenin-dUTP, dinitrophenyl-dUTP or covalently coupled to N-acetoxyacetoaminofluorene. Hybrid sites typically are detected by a two-step antibody incubation and 1-30 nm colloidal gold particles.
Obtaining complementary images with sputter coating and high-vacuum evaporation in an field emission SEM equipped with a cryostage
Authors: Wergin William P. , Erbe Eric F. , Mills Deryck J.
Published: June 2020

An Oxford CT 1500 Cryotrans System was mounted on a Hitachi S-4000 FESEM to perform low temperature manipulations and observations. The sample, consisting of a yeast suspension, was frozen in each of six hinged gold specimen holders, which were clamped onto a complementary freeze-etch specimen cap. The cap was mounted on a precooled modified Oxford holder (Fig. 1), and transferred to the dedicated cryochamber and cryostage where the yeast was fractured, etched and sputter coated with Pt. A second sample, mounted in the same type of gold holders, was frozen, fractured, etched, shadowed with platinum and coated with carbon in a Denton DV-503 high vacuum evaporator equipped with a modified DFE-2 freeze-etch module.1 The standard Oxford specimen transfer device was used to insert the holder through the cryochamber and onto the cold stage in the microscope.
Murine macrophage activation by cisplatin and carboplatin in culture: An scanning electron microscopic study
Authors: Palma J.P. , Aggarwal S.K.
Published: June 2020

In order to study the mechanism of action of the drugs cisplatin and carboplatin in the regression of tumors, we investigated the activation and interaction of murine macrophages and S180 ascites cells. Activated macrophages have been shown to selectively and efficiently lyse tumor cells in culture. Cisplatin activated macrophages have been shown to enhance the capacity to recognize and further lyse Dalton's lymphoma cells in vitro. The present study investigates the interaction of cisplatin or carboplatin treated macrophages and S180 cells using scanning electron microscopy.

Murine macrophages were isolated from the peritoneal cavity and treated with cisplatin (9ug/ml) or carboplatin (50ug/ml) for 2h at 37C. S180 cells or hepatocytes were co-cultured with the activated macrophages for 10min, 30min, 1h, 2h, 6h, 24h, and 48h. Cells were cultured on coverslips in minimal essential medium with fetal bovine serum supplement. Coverslips were fixed 30min in 1.5% glutaraldehyde in 0.5M phosphate buffer (pH 7.2), dehydrated through a graded series of ethanol for 5min each. Samples were critical point dried, sputter coated with gold for 3min and observed under the JEOL JSM 35CF scanning electron microscope at 15 kV.
Ultrastructural changes in murine lymphoma cells exposed to ultraviolet-A radiation
Authors: Thomas Delma P. , Godar Dianne E.
Published: June 2020

Ultraviolet radiation (UVR) from all three waveband regions of the UV spectrum, UVA (320-400 nm), UVB (290-320 nm), and UVC (200-290 nm), can be emitted by some medical devices and consumer products. Sunlamps can expose the blood to a considerable amount of UVR, particularly UVA and/or UVB. The percent transmission of each waveband through the epidermis to the dermis, which contains blood, increases in the order of increasing wavelength: UVC (10%) < UVB (20%) < UVA (30%). To investigate the effects of UVR on white blood cells, we chose transmission electron microscopy to examine the ultrastructure changes in L5178Y-R murine lymphoma cells.
Hexachlorobenzene toxicity in the monkey ovary: III. Ultrastructure induced by high (10 mg/kg) dose exposure
Authors: Singh A. , Dykeman A. , Jarrelf J. , Villeneuve D. C.
Published: June 2020

Hexachlorobenzene (HCB), a persistent and mobile organochlorine pesticide, occurs in environment. HCB has been shown to be present in human follicular fluid. An objective of the present report, which is part of a comprehensive study on reproductive toxicity of HCB, was to determine the cytologic effects of the compound on ovarian follicles in a primate model.

Materials and Methods. Eight Cynomolgus monkeys were housed under controlled conditions at Animal facility of Health and Welfare, Ottawa. Animals were orally administered gelatin capsules containing HCB mixed with glucose in daily dosages of 0.0 or 10 mg/kg b.w. for 90 days; the former was the control group. On the menstrual period following completion of dosing, the monkeys underwent an induction cycle of superovulation. At necropsy, one-half of an ovary from each animal was diced into ca. 2- to 3-mm cubed specimens that were fixed by immersion in 2.5% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.3). Subsequent procedures followed to obtain thin sections that were examined in a Hitachi H-7000 electron microscope have been described earlier.
An ultrastructural study of isolated small vessel endothelial and choroid plexus epithelial cells of ovine brain
Authors: Faso L. , Trowbridge R.S. , Moretz R.C. , Wisniewski H.M.
Published: June 2020

Homeostasis in the central nervous system is maintained by two selective permeability barriers: the blood brain barrier (BBB), made up of capillary endothelial cells (ECs) and the blood cerebral spinal fluid barrier composed of specialized cuboidal epithelial (Ep) cells. The ECs of the BBB contain few profiles of trans-cellular pinocytotic vesicles and form a band of intercellular zonular occludens (ZO) sealing adjacent cells. Choroid plexus Ep cells have on their free surfaces microvilli that are irregularly oriented and expanded at the tips. They also contain juxtaluminal ZO which seal the intercellular spaces. Two cell types, small vessel endothelial cells (ECl) and choroid plexus epithelial cells (SCP), were isolated from ovine brain and established as cell strains. These cells were examined with scanning (SEM) and transmission electron microscopy (TEM) to determine if they retain the features characteristic of the cells in vivo.
Immunoelectron microscopy of bamboo mosaic virus-infected bamboo leaf cells
Authors: Lin Na-Sheng , Chen Chin-Chieh
Published: June 2020

Infection of green bamboo (Bambusa oldhamii Munro), with bamboo mosaic virus (BoMV), a member of the potexvirus group, results in the formation of a large number of unusual electrondense crystalline bodies (EDCB), in addition to virion aggregates, in the infected cells. In order to determine the subcellular site(s) of sequential appearance of EDCB and capsid protein in the infected cells, the infection sequence was followed in leaf tissues. Emerging young leaves of green bamboo that have not yet unrolled were sampled about 2 weeks post-inoculation. Leaf tissues were fixed with glutaraldehyde and embedded in Lowicryl HM20. Ultrathin sections were first treated with 1:200 dilution of anti- BoMV serum followed by gold-labelled goat anti-rabbit IgG.
The relationship of IGE receptor topography to signaling activity in RBL-2H3 mast cells
Authors: Pfeiffer J.R. , Seagrave J.C. , Wofsy C. , Oliver J.M.
Published: June 2020

In RBL-2H3 rat leukemic mast cells, crosslinking IgE-receptor complexes with anti-IgE antibody leads to degranulation. Receptor crosslinking also stimulates the redistribution of receptors on the cell surface, a process that can be observed by labeling the anti-IgE with 15 nm protein A-gold particles as described in Stump et al. (1989), followed by back-scattered electron imaging (BEI) in the scanning electron microscope. We report that anti-IgE binding stimulates the redistribution of IgE-receptor complexes at 37“C from a dispersed topography (singlets and doublets; S/D) to distributions dominated sequentially by short chains, small clusters and large aggregates of crosslinked receptors. These patterns can be observed (Figure 1), quantified (Figure 2) and analyzed statistically. Cells incubated with 1 μg/ml anti-IgE, a concentration that stimulates maximum net secretion, redistribute receptors as far as chains and small clusters during a 15 min incubation period. At 3 and 10 μg/ml anti-IgE, net secretion is reduced and the majority of receptors redistribute rapidly into clusters and large aggregates.
Video-enhanced differential interference contrast light microscopy: A method for semi-automatic object tracking
Authors: Salmon E. D. , Magers S. , Skibbens R. , Gliksman N. R.
Published: June 2020

VE-DIC microscopy can image unresolved objects and cellular fine structure invisible by eye or photographic recording methods with z-axis resolution less than 200 nm. We use VE-DIC methods to obtain detailed kinetic data op the movements of kinetochores, chromosome arms, and centrosomes during mitosis, the assembly of individual microtubules and sickle cell haemoglobin polymers and the translation and rotary activity of microtubule motors. In our video assays, images are recorded at 30 frames/sec on video tape or at 1-2 second intervals on a Panasonic OMDR. We have been tracking object movements by eye using a PC computer to generate a cursor overlay whose position is controlled by a mouse. Although this method is accurate to about 200 nm in our system, human fatigue makes error in individual data points much higher when tracking the movements of objects through many successive frames.
Normal and regenerating rabbit retinal pigment epithelium studied by High voltage electron microscopy
Authors: Korte G. E. , Song M. J.
Published: June 2020

During regeneration the retinal pigment epithelium (RPE) undergoes changes in cell shape and the distribution of organelles. To study these changes we used highvoltage electron microscopy (HVEM) to examine normal RPE cells and cells at different stages of maturation during regeneration induced by iv injections of sodium iodate, in rabbits. This chemical poisons much of the RPE, spared cells serving as a source of a new epithelial sheet. Tissue was processed for routine electron microscopy; serial sections 0.25 or 0.50 μm thick were mounted on Formvar coated slot grids, stained with uranyl acetate and lead citrate, and examined with an AEI 1.2 MV high-voltage electron microscope. Cytological details were observed in stereo pictures and in series of sections that were used to make three-dimensional reconstructions.
Cytoplasmic hybrids, by fusing fish erythrophores and normal rat kidney cells
Authors: Porter K.R. , Anderson K.L.
Published: June 2020

When cultured together in the presence of PEG, these cells fuse (M1,M3) and survive in vitro for several days. This offers an opportunity to explore the capacity of one cell type (highly organized structurally) to impose it's structural features on a relatively unorganized cell type (NRK). Also, with two cells differing in several respects, one can ask questions regarding a role of the cell center in the control of pigment aggregation and dispersion, as well as the capacity of one cell type to assemble pigment granules in the cytplasm of another.

First, in observations on general architecture .the hybrids have numerous microtubules (M3), but not the organized array of thousands observed in the erythrophores (M2). Furthermore, the microtubules in the hybrid are randomly oriented essentially as they are in the NRK cell (M4). There is a tendency observed in the hybrids for the pigment granules to concentrate among the microtubules and the cistemae of the ER (M3). Thus far, however, we have not succeeded consistently with epinephrine to induce aggregation, or with caffeine, dispersion.
LR White acrylic resin polymerized by microwave energy for immuno-EM ofSaccharomyces cerevisiae: A rapid method
Authors: Giammara B. L. , Rose A. O. , Hanker J. S.
Published: June 2020

Microwave embedment methods have been developed for epoxy and polyester resins. Because the thick yeast cell wall is known to inhibit penetration by many embedding media, we wished to use an embedding agent exhibiting favorable properties of hydrophilicity and low viscosity. The complex requirement for low temperature and curing using UV irradiation with the polymer Lowicryl, and recent advantages described for yeast using LR White, made the latter polymer a good candidate for our studies.

Saccharomyces cerevisiaewas grown at 30°C in selective medium to an OD640= 1.0. A modification of the procedure of Tuinen and Riezman was used to fix the cells. Briefly, the cells were washed three times with Sorenson's buffer, pH 7.3, and fixed as a suspension in 3% paraformaldehyde, 0.25% glutaraldehyde in Sorenson's for 2 hours at room temperature. The cells were again washed three times followed by incubation in 1 % sodium meta-periodate at room temperature for one hour.
Early experience with a 300kV FEG STEM
Authors: Garratt-Reed Anthony J. , Harrach Sebastian von
Published: June 2020

At the time of writing, a model VG HB603 300kV analytical scanning transmission electron microscope with a field-emission gun (FEG-STEM) is undergoing its final evaluation for acceptance at MIT. The instrument as supplied has an electrostatic gun lens, two magnetic condenser lenses, a symmetric objective lens with a spherical aberration coefficient of 4.5mm., and three post-specimen lenses intended for minimizing distortion of the diffraction patterns while changing camera length. The specimen holder is of the side-entry type, with “z-adjustment” (i.e. control of the specimen position along the microscope axis). For single-tilt applications a holder accepting three specimens simultaneously is provided, which, together with the double-tilt holder, has all parts near the sample made of beryllium. The point-to-point resolution in the image is computed to be 0.28nm. X-axis tilt is +/-600, and, in the double-tilt holder, Y-axis tilt is +/-45°.
Development of a 300kV ultrahigh resolution analytical electron microscope
Authors: Fukushima Kurio , Arai Yoshihiro , Kawasaki Masahiro , Kokubo Yasushi
Published: June 2020

Intended for atomic-level observation and analysis in the material science field, a 300 kV ultrahigh resolution analytical electron microscope (UHRAEM) has been newly developed on the basis of the JEM-2010, a 200 kV UHRAEM. There are two versions: the UHR version, intended for ultrahigh resolution observation with a point resolution of 0.17 nm and the multi-purpose HT version, featuring specimen tilt angles as large as± 40° , and heating and cooling holders. The external view of the instrument is shown in Fig.1. Some characteristic features of the 300 kV UHRAEM are shown as follows.

Electron Gun: An extremely stable and compact 300 kV election gun is constructed with 10-stage accelerating tube. SF6 gas is used for electric insulation.
An electron optical tool kit for transmission and surface electron microscopy
Authors: Veneklasen Lee H.
Published: June 2020

This speculative discussion is offered in memory of Prof. Ben Siegel's fascination with the science of microscope instrumentation. It views the microscope configuration as a set of tools for creating observational opportunities. The central element is a condensor/objective lens in which the specimen is immersed, and along whose axis lie conjugate image and diffraction planes. An illumination system sets up beam conditions, in mode l1, forming a parallel beam, and Mode l2 forming a probe at the center of the lens. A projection system determines the plane within the objective that is magnified onto a recording detector surface. Projection mode P1, views the plane at the lens center, while projection mode P2 views the back focal or diffraction plane behind the lens. These two lens systems, along with apertures, scan coils, and detectors establish various modes of operation which make up the microscopist “tool kit”.
Three-dimensional morphometry of biological fine structure using HVEM stereo images
Authors: Hama Kiyoshi
Published: June 2020

There are several approaches of extracting three dimensional (3D) morphometrical information from biological fine structures, computer 3D reconstruction using thin serial sections, stereologica1 analysis of random thin section images, reconstruction from the results obtained by Fourier analysis of continuously tilted images, and so on. We have developed a computer analysis method of HVEM stereo images of thick biological specimens. Each method has advantages and disadvantages and one can choose one or other method according to the nature of samples and/or the nature of the required information.

In our method, stereo paired electron micrographs are processed to produce skeletonized images, they are automatically traced, and the z coordinates of the given specimen points are calculated from the parallaxes between the two tilted images and the tilt angle.
Computer-aided image analysis and graphics in biological microscopy at higher voltages
Authors: Carragher B. , Hessler D. F. , Hinshaw J. E. , Martone M. , Milligan R. A. , Young S. J. , Ellisman M. H.
Published: June 2020

The range of problems accessible to study using high voltage microscopy encompasses structures that span a wide range of dimensions from Angstroms to tens of microns. Structurally oriented cell biologists and neurobiologists examine cells, tissues, organelles and macromolecules in order to gain insight into cellular and molecular physiology by relating structure to function. Comprehension of these structures can be greatly enhanced by the application of computer aided three dimensional reconstruction and analysis techniques.

The past decade has seen an explosive growth in the capabilities for the digital acquisition of images. At the same time, the availability of relatively inexpensive graphics workstations and sophisticated image processing and analysis software packages has made graphics and imaging techniques accessible to most research laboratories. However, the complexity of problems studied in the biological sciences has always presented a challenge to the techniques used in the analysis, and methods based on computer graphics are certainly no exception to this rule.
Research thrusts and the BRITE-EURAM project
Authors: Van Dyck D.
Published: June 2020

The most performant high resolution electron microscopes nowadays achieve a resolution of about 0.2 nm so that the structural details of matter can be visualised at the atomic scale.

If a resolution of 0.1 nm could be reached, most of the individual atoms of a structure could be resolved which would make high resolution electron microscopy (HREM) an extremely and unparalleled technique for the study of materials, especially for the characterisation of the structure of defects, new materials, crystalline as well as disordered and amorphous, etc. However, the potential power of the technique is still severely limited by the problem of the interpretation of the images. Thus far, the only way to obtain reliable information is by comparing simultaneously the experimental images with computer calculated images for various structure models. However, this trial and error technique requires a large amount of prior information obtained by other techniques and makes HREM much more dependent and thus much less powerful. For complicated structures such as defects, disordered and amorphous materials, hardly no reliable information can be obtained at present.
Resolution in near-field optical microscopy
Authors: Isaacson M.
Published: June 2020

It has only been within the last half decade that the concept of super resolution microscopy in the near-field has been vigorously pursued and experimentally demonstrated. However, the idea of optical resolution unhindered by far field diffraction limitations was conceived more than a half century ago by Synge and further elaborated by O'Keefe in the fifties. That die method was possible, however, was only first demonstrated using 3cm wavelength microwaves almost 20 years later.

The basic principles of the method of near field scanning optical microscopy (NSOM) have been described before in the literature. Briefly, the idea is as follows: if an optical probe (source or detector) of diameter D is positioned within a distance of approximately D/π from the surface of an object, and the reflected, transmitted or emitted light is detected, then the lateral spatial region from which the information occurs is limited to aregion of approximate size D and not by the wavelength of the illuminated or detected light.
“Resolution” in atomic-resolution Electron microscopy
Authors: O'Keefe Michael A. , Spence John C.H.
Published: June 2020

The Rayleigh resolution criterion was developed for incoherent imaging conditions and cannot, in general, be applied to coherent high-resolution transmission electron microscopy (HRTEM). In fact, the Rayleigh criterion may lead to paradoxical results since it considers only two scatterers and does not account for the signal-to-noise ratio. It may, however, be used for dark-field HAAD STEM imaging. For the case of strong multiple scattering in HRTEM lattice imaging, the only general relations that can be assumed between the image of a specimen and its projected crystal potential are those imposed by symmetry, and the “local” HRTEM column approximation. The effects of limited resolution may produce an image of lower symmetry than that of the object. Also, misalignment along symmetry axes may preserve some symmetry elements. Under coherent conditions the ability to distinguish atoms in an image depends on their scattering phases, which are a property of the sample.
Automatic electron tomography
Authors: Typke D. , Dierksen K. , Baumeister W.
Published: June 2020

The new generation of microprocessor-controlled electron microscopes in combination with large-area CCD arrays and fast image processing computers enables automatic control of complex imaging procedures. Using a Philips CM 20 CTEM equipped with a Photometries 1Kx1K CCD camera and a TEMDIPS computer, we have set up automatic recording of tilt series for tomographic 3D reconstruction. It is our goal to combine automatic recording with on-line processing of the measured data.

Fig. 1 shows a scheme of the experimental set-up. As the goniometer is not incorporated in the microprocessor control of the CM 20, an accurate readout of the tilt angle (resolution 0.01 deg.) and an additional board in the external computer driving the goniometer motor have been installed. The CCD camera is mounted on a pivotable flange; this allows to adjust its orientation with respect to the tilt axis direction in the image. For magnifications higher than 5,000x it is necessary to correct for image displacements caused by the limited mechanical accuracy of the goniometer (ca. +/-1 μm).
Epitaxy and diffusion-induced recrystallization in gold/copper films
Authors: Tan E.K. , Dregia S. A.
Published: June 2020

Most previous studies of epitaxy have shown that growth of fee thin films on fee substrates leads to parallel, cube-on-cube orientation relationships. However, recent studies of Ag/Ni interfaces indicated that non-parallel orientation relationships may be preferred in fcc/fcc systems of large misfit. One objective of this study is to investigate the orientation relationships produced by epitaxy in Au/Cu bilayers. The Au/Cu system is especially interesting because it has complete mutual solid solubility despite the large lattice parameter misfit (∼ 12%). Hence, the second objective of this study is to investigate low-temperature interfacial diffusion phenomena in the special microstructures produced by multivariant epitaxy.
Atomic structure of interface of intermetallic compound TiAl and nitride Ti2AIN using HREM and image processing
Authors: Sukedai E. , Mabuchi H. , Hashimoto H. , Nakayama Y.
Published: June 2020

In order to improve the mechanical properties of an intermetal1ic compound TiAl, a composite material of TiAl involving a second phase Ti2AIN was prepared by a new combustion reaction method. It is found that Ti2AIN (hexagonal structure) is a rod shape as shown in Fig.1 and its side surface is almost parallel to the basal plane, and this composite material has distinguished strength at elevated temperature and considerable toughness at room temperature comparing with TiAl single phase material. Since the property of the interface of composite materials has strong influences to their mechanical properties, the structure of the interface of intermetallic compound and nitride on the areas corresponding to 2, 3 and 4 as shown in Fig.1 was investigated using high resolution electron microscopy and image processing.
Granular bainite or granular ferrite? A preliminary TEM investigation of an HSLA-100 steel
Authors: Varughese R. , Thompson S. W. , Howell P. R.
Published: June 2020

Ever since Habraken and Economopoulos first employed the term granular bainite to classify certain unconventional transformation products in continuously cooled steels, the term has been widely accepted and used, despite the lack of a clear consensus as to the detailed nature of the transformation products which constitute granular bainite. This paper presents the preliminary results of a TEM investigation of an 0.04 wt% C, copper-containing steel (designated HSLA-100). It is suggested that the term granular ferrite rather than granular bainite is a more accurate description of this multiphase reaction product.

Figure 1 is a light micrograph of a sample which had been air-cooled from 900°C to room temperature. The microstructure is typical of that which has been termed granular bainite in the past and appears to consist of equiaxed ferritic grains together with other minor transformation products. In order to examine these structures in more detail, both continuously cooled and isothermally transformed and quenched materials have been examined with TEM. Granular bainite has been found in virtually all samples.
The role of interphase boundary phenomena on mechanical behavior during high-temperature deformation
Authors: Hidalgo-Prada B.
Published: June 2020

The influence of interphase boundary on the mechanical behavior of a two-phase (α/β) Ni-Modified Ti-6A1-4V alloy during superplastic deformation (SPD), has been investigated in the range of temperature and strain rate where maximum ductility is - attained.

Uniaxial tests for constant and differential strain rates were performed over the - range of 5.0 x 10-5 s-1 to 5.0 x 10-3 s-1 and at temperature from 1023 to 1123 K. To optimize the initial microstructure, tensile specimens were static annealed in argon for 1 hour at 815 °C ( SA-1-815).

Upon completion of the tests, specimens were quenched in pre-chilled argon to pre—serve the high temperature microstructure for metallographic analysis. The gage portion of the specimen was polished and etched in a solution of 2 ml HF, 3 ml HNO3 and 95 ml H2O. Subsequently, they were subjected to scanning and transmission electron - microscopy (SEM and TEM) examination. A Quantimet Image Analizer was used for determining the phase size, its distribution and volume fractions.
Parallel EELS as a complementary tool in an Analytical TEM study of metal alloys
Authors: Guerra R.E. , Rightor E.G.
Published: June 2020

The advent of efficient parallel-detection electron energy loss spectrometers (EELS) in analytical transmission electron microscopes (ATEM) promotes rapid elemental characterization of various materials containing light, as well as heavy, elements at high spatial resolution. In the current study, the microstructures of Udimet 520 and HK-25 were investigated to integrate advances in parallel EELS methods with other ATEM techniques.

Thin foils of Udimet 520, a nickel based heat-resistant superalloy, were obtained using common ion milling techniques. Precipitates of the HK-25, a heat resistant steel alloy, were obtained by etching (with Marble's reagent) a polished surface, extracting with a replicating Parlodian film, dissolving the film with amyl acetate and dispersing the resulting particles on holey carbon grids. A JEOL 2000FX ATEM fitted with a Gatan Model 666 EELS system was operated at 200 kV for studies of these alloys.
High-resolution REM of the reconstruction of sapphire surfaces
Authors: Liu J.
Published: June 2020

Sapphire (α-Al2O3) is widely used in industry and research as a high temperature insulator, a substrate for growing thin films and carrier materials in catalysis. It is important to understand the surface properties of the substrate materials for thin film growth and for metal support interactions. Recently RHEED (reflection high energy electron diffraction) and REM (reflection electron microscopy) techniques have been used to characterize surface properties of sapphire annealed in air or in oxygen. The presentpaper reports some results of high resolution REM imaging of lattice fringes of reconstructed sapphire surface.

The sample preparation procedure was reported elsewhere. The results presented here were obtained from a sample annealed in pure oxygen at 1650° C for 72 h. The high resolution REM observations were done in a Philips 400T transmission electron microscope operated at 120 kV with a vacuum pressure about 10-7 Torr.
Analysis of ion-induced damage in GaAs etched with chemically reactive SiCl4
Authors: Cole M. W. , Saliman S. , Cooper C. B. , Dutta M.
Published: June 2020

Reactive ion etching (RIE) is an important technique for the fabrication of III-V semiconductor devices. Although RIE has demonstrated high - resolution fabrication of structures and devices on the sub-micron scale there is concern that this technique may introduce damage which may limit its utility. Previous work regarding the material quality of these etched surfaces indicates the presence of undesirable radiation damage and material contamination resultant from the RIE process. The consequences of this damage undoubtably leads to deterioration in device performance. In the present work we have applied microstructural (transmission electron microscopy, TEM), optical (Raman Scattering & photo luminescence, PL) and electrical characterization methods to study the residual damage incurred by dry etching with chemically reactive SiCl4. We have systematically evaluated changes in the structural and electronic properties as a function of critical etch parameters in order to optimize SiCl4 RIE for device processing.
Observing dislocations with ADF-STEM
Authors: Huang Y. , Cowley J. M.
Published: June 2020

Scanning transmission electron microscopy (STEM) with a high angle annular detector has become a useful technique in material science. The atomic number sensitive contrast (Z-contrast) of the Annular Dark-Field (ADF) image is good for looking at the distribution of heavy elements in a relatively light substrate. In many cases the impurity distributions are substantially affected by the defects in the materials and their interaction with the impurities. Therefore it is also desirable to observe defects with ADF images. This is possible and has some advantages over normal STEM. We have studied the ADF imaging of dislocations, its contrast mechanism and visibility in the ADF image.
Applications of electron holography to multilayer interfaces
Authors: Weiss J. K. , de Ruijter W. J. , Gajdardziska-Josifovska M. , Smith David J. , Voelkl E. , Lichte H.
Published: June 2020

Electron holography has received renewed interest recently as a means of resolution enhancement in high resolution phase contrast imaging and as a technique for imaging microscopic magnetic domain structures. Some of the original applications of the technique involved measurement of the absolute mean inner potential in films of known thickness. This approach has now been extended in order to gain information about changes in elemental concentrations at interfaces in multilayer films.

The abruptness of interfaces in multilayer films used for X-ray mirrors strongly affects their reflective properties. Previous studies using high resolution phase contrast imaging have shown that this interface diffuseness can be imaged, but typically with low contrast and an unknown contribution from amplitude contrast effects. The differences in mean inner potential between successive layers suggests that the variation of the mean inner potential across the interface should be a good measurement of the change in elemental concentration.
Probe-shifting method in in-line holography
Authors: Wang Shi-Yao , Cowley J.M.
Published: June 2020

In-line holography was Gabor's idea to record the interference patterns between the directly transmitted beam and the diffracted beams (hologram), and subsequently to determine the amplitude and phase of the object from the hologram by some reconstruction procedures. As has been pointed out by many authors, a fundamental limitation of in-line holography is that the reconstruction will produce two superimposed images, the desired real image of the object and a defocused, aberrated, conjugate image. Although this conjugate image could be completely removed by introducing off-line holography, efforts continued to reconstruct in-line holograms with the least conjugate image disturbance. Lin and Cowley suggested that by using the scanning ability of STEM, it could be possible to reduce this disturbance. Here we want to further check and develop the applicability of this method.
Application of hollow-cone illumination to High-resolution electron microscopy
Authors: Herring R.A.
Published: June 2020

TEM hollow cone illumination can produce high resolution images having atomic number (Z) contrast within a lattice image. Inorder to produce these images, the contribution of four sources of electrons should be considered. These are the main, inelastically scattered, elastically scattered, and diffracted beams. This abstract discusses these sources of electrons to the hollow cone (HC) image, and then goes further to propose a possible method of extending the resolution of the electron microscope by using diffracted HC beams to form holograms which should remove the limitation on resolution imposed by the objective lens and inelastically scattered electrons. A Philips EM 430T was used to take the electron micrographs.
Materials science applications of a 120kV FEG TEM/STEM: Triskaidekaphilia
Authors: Bentley J. , Fisher A. T. , Kenik E. A. , Wang Z. L.
Published: June 2020

The introduction by several manufacturers of 200kV transmission electron microscopes (TEM) equipped with field emission guns affords the opportunity to assess their potential impact on materials science by examining applications of similar 100-120kV instruments that have been in use for more than a decade. This summary is based on results from a Philips EM400T/FEG configured as an analytical electron microscope (AEM) with a 6585 scanning transmission (STEM) unit, ED AX 9100/70 or 9900 energy dispersive X-ray spectroscopy (EDS) systems, and Gatan 607 serial- or 666 parallel-detection electron energy-loss spectrometers (EELS). Examples in four areas that illustrate applications that are impossible or so difficult as to be impracticable with conventional thermionic electron guns are described below.
Correcting channeling and diffraction effects in quantitative REELS surface microanalysis
Authors: Wang Z. L. , Bentley J.
Published: June 2020

Channeling conditions or resonance conditions have to be satisfied in order to enhance image contrast in reflection electron microscopy (REM) and the signal-to-background ratio in reflection electron energy-loss spectroscopy (REELS). The introduction of the channeling and diffraction effects can complicate surface microanalysis (Fig. 1). In REELS, the composition ratio for two elements may be determined by

(1)

where σ(A,β,Δ) is the single-atom ionization cross-section of element A for collection semi-angle β and energy window Δ; iA is the average local (channeling) current density at A atom sites; NA is the average atomic concentration of A atoms; σeff(A,β,Δ) is defined as an effective ionization cross-section (EICS) of element A; IA(β,Δ) is the integrated core-loss intensity for element A; and KA is introduced to take into account the deviation of the final inelastic electron angular distribution from the Lorentzian function due to dynamical diffraction effects. Equivalent symbols apply to element B.
Inelastic scattering probability for electrons traveling through the oxide in an MOS heterostructure
Authors: Turowski Marek A. , Kelly Thomas F. , Batson Philip E.
Published: June 2020

Al/SiO2/Si (MOS) heterostructures which are typical of actual electronic devices have been studied with high spatial resolution scanning transmission electron microscopy (STEM). As the starting material for a cross-section view TEM sample, the n-type, 4" silicon wafer with 40 ran thick, thermally grown silicon dioxide and 120 nm thick aluminum overlayer was used. Sample preparation procedures and experimental conditions have been described elsewhere. Electron energy loss spectra were recorded over the low-loss region (0 to 100 eV) at 1, 2 and up to 5 nm intervals across interfaces in all three materials. The energy loss function was then obtained from experimental spectra after Fourier-log deconvolution of multiple scattering. We found the structure in the energy loss spectra below the bulk plasmon energy in the vicinity of either interface. They included 3.5 - 4 eV and 7 - 8 eV peaks as clearly seen in Fig.1.
The standard hole-count test: A progress report
Authors: Lyman C. E. , Ackland D. W.
Published: June 2020

Analytical electron microscopy (AEM) was well served by the original hole count test that prompted microscope manufacturers to reduce, by an order of magnitude, spurious x-ray generation in the specimen. This spurious x-ray signal is caused by hard x-rays or uncollimated electrons from the illumination system and is typically generated over the entire specimen regardless of where the electron probe is placed for analysis. The original test was performed on an ion-milled thin foil disk specimen of Ag or Mo, but the absolute value of hole count was dependent upon both specimen and operator. To make progress in die reduction of spurious xrays at intermediate voltages (if the problem is present), a hole-count test on a standard specimen that does not require operator judgement would be useful. The ultimate goal would be to reduce spurious x-rays to a level that would not affect any experiment on any specimen.
Nanoanalysis of semi-insulating polycrystalline silicon by high-spatial-resolution electron microscopy
Authors: Catalano M. , Kim M.J. , Carpenter R.W. , Wong J.
Published: June 2020

Semi-insulating polycrystalline silicon (SIPOS) has been used extensively as a passivating layer in highvoltage power devices and as the wide bandgap material in solar cells. Little information, however, is available on the nano-scale nature of oxygen distribution and its redistribution upon thermal annealing, and the rnicrostructural characteristics of SIPOS thin films. In the present study, the atomic structure of SIPOS layers on Si wafers was characterized by HREM and the oxygen content was quantitatively determined by nanospectroscopy.

SIPOS films were chemical vapor deposited on Si {001} wafers from a preset mixture of SiH4 and N2O. Annealing was done in dry N2 at 900°C for 30 min. Cross-sectional TEM specimens were prepared from both as-deposited and annealed materials. HREM was done in an ISI-002B at 200kV. Nanospectroscopy was performed at 100kV in a Philips EM400ST/FEG microscope coupled to a Gatan parallel-detection EELS, with better than 3 nm spatial resolution.
Annealing effects on the microstructure of titanium electrical contacts on diamond films
Authors: Ma G-H. M. , Evans N. D. , Tachibana T. , Clausing R. E. , Glass J. T.
Published: June 2020

With its large band gap and a unique combination of many excellent properties, diamond is regarded as an excellent candidate for making electronic devices for operation at high temperature. In order to fabricate diamond devices, suitable electrical contacts and appropriate deposition techniques must be developed. Titanium is considered a suitable candidate material for diamond electrical contacts based on its properties. Recent current-voltage (I-V) measurements showed that as-deposited titanium contacts on boron-doped semiconducting diamond are rectifying in nature. However, upon post-deposition annealing at 430 °C, these contacts became ohmic. Surface analysis by X-ray photoelectron spectroscopy of these annealed metal contacts showed interfacial metal carbide formation at the metal/diamond interface. 1 Therefore, the microstructural evolution causing these metal contacts to change from rectifying to ohmic in nature is the primary purpose of the present research.
Study of the resistor material of an automotive spark plug by use of the charge-up effect along with elemental mapping in an electron microprobe
Authors: Liu D. R. , Shinozaki S. S. , Park J. S. , Juterbock B. N.
Published: June 2020

The electric and thermal properties of the resistor material in an automotive spark plug should be stable during its service lifetime. Containing many elements and many phases, this material has a very complex microstructure. Elemental mapping with an electron microprobe can reveal the distribution of all relevant elements throughout the sample. In this work, it is demonstrated that the charge-up effect, which would distort an electron image and, therefore, is normally to be avoided in an electron imaging work, could be used to advantage to reveal conductive and resistive zones in a sample. Its combination with elemental mapping can provide valuable insight into the underlying conductivity mechanism of the resistor.

This work was performed in a CAMECA SX-50 microprobe. The spark plug used in the present report was a commercial product taken from the shelf. It was sectioned to expose the cross section of the resistor. The resistor was known not to contain the precious metal Au as checked on the carbon coated sample. The sample was then stripped of carbon coating and re-coated with Au.
Scanning electron microscopy with polarization analysis: An update
Authors: Unguris J. , Hart M. W. , Celotta R. J. , Pierce D. T.
Published: June 2020

Over the past ten years the technique of scanning electron microscopy with polarization analysis (SEMPA) has rapidly evolved from a scientific curiosity to a useful analytical tool for looking at a material's magnetic microstructure. Several reviews of the technique have been published elsewhere. SEMPA has been successfully used to analyze various technological problems such as: noise in magnetic and magneto-optical recording media, domain wall motion in thin film recording heads, and domain structures in small Permalloy shapes. Basic science applications of SEMPA include quantitative studies of the influence of the surface on the structure of magnetic domains and domain walls, and studies of magnetic microstructures in ultra-thin (0.1 - 1 nm) ferromagnetic films. Many current applications of SEMPA make use of the technique's surface sensitivity to probe the magnetism of thin films and multilayers.
A study of the magnetic structure of magnetic force microscope tips using transmission electron microscopy
Authors: McVitie S. , Hartmann U.
Published: June 2020

Magnetic force microscopy (MFM) has become an important tool in the investigation of the micromagnetic structure of magnetic systems. The interaction of stray magnetic field from a sample with a sharp magnetic tip is measured as the tip is scanned across the surface of the sample. Characterisation of the tip-sample interaction is of paramount importance if the measured signal obtained by MFM is to be put on a quantitative basis. In this paper we describe the preliminary results obtained by studying MFM tips using the Lorentz techniques of transmission electron microscopy.

The MFM tips were prepared from 25nm thick Ni wire by an electrolytic etching and polishing technique which produces tips with a sharp apex of radius <100nm. The nature of the tips meant that only the very end of the tips were thin enough to be observed using 200kV electrons in TEM.
Transmission electron microscopy studies of Bi-substituted garnet films
Authors: Labun P.A. , Crazier P.A. , Suzuki T.
Published: June 2020

Bi-substituted garnet films have attracted much attention as possible materials for high density magneto-optical recording media. Recently a new rapid thermal annealing technique has been developed to produce garnet films with improved microstructural and magnetic properties. We have employed in-situ heating in an analytical electron microscope to characterize the microstructural changes to the morphology and chemistry during thermal annealing of garnet films.

Garnet films were produced by an r.f. magnetron sputter deposition method in an Ar atmosphere. The nominal composition of the films was (BiDy)3(FeGa)5O12 with a thickness of ∼ 40 nm. The films were transferred into the hot stage of a Philips 400T transmission electron microscope and heated to a maximum temperature of 720 C. Different rates were used to simulate the effect of heat pulsed annealing.