bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Chemical Impurities in Glutaraldehyde
Authors: Grenon B. J. , Tousimis A. J.
Published: June 2020

Ever since the introduction of glutaraldehyde as a fixative in electron microscopy of biological specimens, the identification of impurities and consequently their effects on biologic ultrastructure have been under investigation. Several reports postulate that the impurities of glutaraldehyde, used as a fixative, are glutaric acid, glutaraldehyde polymer, acrolein and glutaraldoxime.

Analysis of commercially available biological or technical grade glutaraldehyde revealed two major impurity components, none of which has been reported. The first compound is a colorless, water-soluble liquid with a boiling point of 42°C at 16 mm. Utilizing Nuclear Magnetic Resonance (NMR) spectroscopic analysis, this compound has been identified to be — dihydro-2-ethoxy 2H-pyran. This impurity component of the glutaraldehyde biological or technical grades has an UV absorption peak at 235nm. The second compound is a white amorphous solid which is insoluble in water and has a melting point of 80-82°C. Initial chemical analysis indicates that this compound is an aldol condensation product(s) of glutaraldehyde.
Borates as Agents for Negative Staining
Authors: Massover William H.
Published: June 2020

Negatively stained biological specimens generally can reveal information only to the quaternary level of macromolecular ultrastructure. In addition to the damaging influences of electron irradiation (e.g., 1), this limitation is due to such factors as the relatively large size of the staining agents being used, the physical and chemical interactions of the stain with the wet specimens, and the lack of a stable amorphous state in the dried stain. All heavy metal negative stains give much more contrast than is actually needed to reveal and record information; agents containing lighter atoms might provide improved qualities in some of the non-optical aspects while still giving adequate contrast. A preliminary study has shown that aluminum potassium sulfate and sodium tetraborate can function successfully as negative stains despite their lack of any heavy atom content. The tetraborate stain has provided information about ferritin and apoferritin that was not revealed with the usual stains.
Screening Electron Microscopy Sections with PolanretTM Light Microscope
Authors: Turner J. N. , Lillibridge C. B. , Meltzer R. J. , Park E. D.
Published: June 2020

A new, variable phase contrast microscope, the PolanretTM, has been developed which is particularly suited to the optical screening of thin sections for electron microscopy with regard to tissue orientation and section quality.

By preliminary examination, defects in preparation of the specimen can be discovered immediately after sectioning and prior to staining or examination with the electron microscope. Such examination of unprocessed sections which are thinner than conventional light microscopy sections is possible because the Polanret TM system can make exceptionally small differences in optical path. Using the PolanretTM microscope, the phase and amplitude can be adjusted continuously so as to achieve optimum specimen contrast. The microscope can thus be used to visualize specimen defects and intracellular details in a way which conventional phase microscopy is unable to do.

This preliminary screening technique was evaluated for its usefulness in detecting microtome knife defects, i.e., scratches and chatter, so that corrective measures could be taken.
Enzyme Digestion of Epon Embedded Akinetic Cilia
Authors: Hess R. A. , Thurston R. J. , Kilburn K. H.
Published: June 2020

Terminal gill cilia of the freshwater mussel Unio stop beating when exposed to hyperosmolar solutions. Ultrastructural studies of the cilia during akinesia showed the absence of the 9+2 doublet microtubules and the ciliary matrix was amorphous and extremely electron dense (Fig. 2). It seemed possible that the axonemal microtubules might not be disrupted by shock-stopping cilia, but rather were obscured by the formation of the pleomorphic matrices. This hypothesis was tested using a modified enzymatic proceedure which has been shown to specifically digest spermatozoa flagellar microtubules in Epon ultrathin sections.

Terminal gill filaments with control cilia beating in aged tap water and akinetic cilia which had been exposed to 0.154 M NaCl were fixed at 22°C for 30 min in 3% phosphate buffered (pH 7.35) glutaraldehyde and post-fixed at 22°C for 30 min in 2% buffered osmium tetroxide. The gills were rinsed in buffer, dehydrated in ethanol and embedded in Epon 812.
The Effect of P-Chlorophenylalanine on the Action of Potassium Ions on Mytilus Cilia
Authors: Paparo Anthony A. , Murphy Judith A.
Published: June 2020

The cilioexcitatory effects of 5-hydroxytryptamine(5-HT) has been observed in Mytilus. Its presence has been demonstrated by photofluorometry, bioassay and paper chromatography. Enzymes have been proved to exist not only for the biosynthesis of 5-HT, but also for its oxidation. The evidence thus far indicates that 5-HT is the principal endogenous cilioexcitatory substance involved in the nervous control of ciliary activity in the gill of Mytilus. The available evidence suggests that the decrease in 5-HT after administration of p-chlorophenylalanine(PCPA) is mediated by a decrease in the synthesis of 5-HT resulting from an inhibition of the rate limiting enzyme, tryptophan hydroxylase. Investigators propose that PCPA is incorporated into tryptophan hydroxylase at or near the active site and is responsible for the irreversible inhibition which persists for several days. The present study investigates the effect of PCPA on potassium(K) enhancement of ciliary activity.
Characterization of Rapidly Solidified Aluminum-Lithium Alloys
Authors: Gayle Frank W. , VanderSande John B.
Published: June 2020

Aluminum-lithium alloys are presently the subject of much research due to the effectiveness of lithium in reducing density, raising elastic modulus and providing for high strength. The strengthening precipitate is the metastable, L12-ordered Al3Li (Cu3Au prototype), or δ'. In binary alloys, δ’ precipitates homogeneously with a spherical shape, coherent with the aluminum matrix. These lithium-containing alloys suffer from poor ductility and fracture toughness, however, which has been attributed to 1) the shear-able nature of the δ’ precipitate, resulting in work softening and slip localization on the relevant slip planes, and 2) precipitate free zone formation along high angle grain boundaries.

In a previous paper we proposed that Zr could partially substitute for Li in δ', resulting in a ternary Al3(Li,Zr) phase, which we call δ”. It was anticipated that such a phase would be more resistant to dislocation shear than δ’ from observation of deformation behavior of Al-Zr alloys containing the coherent L12-ordered Al3Zr precipitate.
Spherulite Structures in a Melt Spun Fe-Ni Austenitic Steel
Authors: Michal G. M. , Glasgow T. K. , Moore T. J.
Published: June 2020

Large additions of B to Fe-Ni alloys can lead to the formation of an amorphous structure, if the alloy is rapidly cooled from the liquid state to room temperature. Isothermal aging of such structures at elevated temperatures causes crystallization to occur. Commonly such crystallization pro ceeds by the nucleation and growth of spherulites which are spherical crystalline bodies of radiating crystal fibers. Spherulite features were found in the present study in a rapidly solidified alloy that was fully crysstalline as-cast. This alloy was part of a program to develop an austenitic steel for elevated temperature applications by strengthening it with TiB2. The alloy contained a relatively large percentage of B, not to induce an amorphous structure, but only as a consequence of trying to obtain a large volume fracture of TiB2 in the completely processed alloy. The observation of spherulitic features in this alloy is described herein. Utilization of the large range of useful magnifications obtainable in a modern TEM, when a suitably thinned foil is available, was a key element in this analysis.
Microstructural Variations in Melt-Spun Rapidly Solidified Ribbons
Authors: Bendersky L. A. , Boettinger W. J.
Published: June 2020

Rapid solidification produces a wide variety of sub-micron scale microstructure. Generally, the microstructure depends on the imposed melt undercooling and heat extraction rate. The microstructure can vary strongly not only due to processing parameters changes but also during the process itself, as a result of recalescence. Hence, careful examination of different locations in rapidly solidified products should be performed. Additionally, post-solidification solid-state reactions can alter the microstructure.

The objective of the present work is to demonstrate the strong microstructural changes in different regions of melt-spun ribbon for three different alloys. The locations of the analyzed structures were near the wheel side (W) and near the center (C) of the ribbons. The TEM specimens were prepared by selective electropolishing or ion milling.
HREM Characterization of Oxidfs and Sulfidfs
Authors: Dominguez-Esquivel J.M. , Vazquez-Zavala A. , Puentes-Moyado S.
Published: June 2020

For thin enough crystals the weak-phase object approximation (WPO) is valid, making it possible a direct relationship between the diffracted intensities (i.e. in the image-plane) and the crystal projected potential, i. e. Idα ø (x,y). At the optimum focus conditions the electron diffraction intensities, in the hack-focal plane of the objective, are equivalent to the intensities in the optical transforms (i.e. power spectrum) taken from a high-resolution micrograph. That result, reported by Tanji and Hashimoto, provides a method to characterize the microstructure of materials at the sub-unit-cell level resolution, by means of the micro- diffraction pattern obtained by laser optical diffractometry (LOD). Therefore, structural aspects in Mo oxides and sulfides, that are not unambiguously assessed from the real-space images, can be characterized and complementary information from microregions of 1- to 3-unit cells diameter can be obtained, provided that the WPO assumptions hold (i.e. Thickness less than 200 Å, Id<<IQ).
Suppression of Amplitude Effects In Bright-Field Stem Phase Contrast Imaging
Authors: Butler J. H.
Published: June 2020

Nearly all past Investigations Into the nature of the bright field Image in the STEM as a function of detector aperture size are based on the Scherzer conditions for optimum Imaging. Consequently, they are of limited use when applied to any but the thinnest of specimens. Here we examine Image contrast and resolution as the Scherzer conditions are relaxed in conjunction with detector size, and show that Image quality for strong phase objects can be significantly Improved because, in a certain configuration, amplitude contrast effects can be eliminated, while the phase contrast signal to noise ratio assumes a relative maximum. Thus, if the user is willing to make small sacrifices (≅5%) in resolution and contrast, it should be possible to obtain an amplitude effect free, pure phase contrast Image even for slightly thicker specimens.
A SEM/TEM Investigation of a Polymer Membrane
Authors: Voegele-Kliewer C. E.
Published: June 2020

INTRODUCTION. Polymeric membranes are being developed for a number of technologically important separation processes. Thus a basic understanding of their microstructure has become vital not only in the development of membranes more suitable to current requirements but also in the formation of polymers for future applications. This investigation describes the electron microscopy techniques used to characterize microstructural features which correlate with membrane separation processes.

EXPERIMENTAL. An experimental membrane was examined using both a CAMSCAN SERIES IV SEM and a JEOL 1200EX STEM. The material was prepared for SEM examination using conventional freeze fracturing techniques. A low accelerating voltage, 20kV, was used to reduce the possibility of beam damage in the SEM. The membrane was prepared for examination in the TEM by using a technique described by L. Sawyer.
Particle Contents of Human Lungs
Authors: Stettler L.E. , Platek S.F. , Groth D.H. , Green F.H.Y. , Vallyathan V.
Published: June 2020

Scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA) have been used by numerous investigators to study the particle content of human lungs. Most of this work has been performed on lung specimens from subjects with known or suspected lung diseases. The object of these analyses has been an attempt to relate the composition and concentration of the particles present in the lungs to the lung disease. A major factor missing from past microanalysis work has been data from typical “normal” lungs with which the analyses of diseased lungs could be compared. Currently in progress at NIOSH, is a study in which the particle contents of 96 urban lungs from the Cincinnati, Ohio area are being determined.

Preliminary results for thirty-five of these lung samples will be presented and discussed in the report. When completed, the analysis data will serve as background or baseline data for typical urban lungs with which comparisons of the particle contents of diseased lungs can be made.
A New Detector System For The HB5 Stem Instrument
Authors: Cowley J.M.
Published: June 2020

The HB5 STEM instrument at ASU has been modified previously to include an efficient two-dimensional detector incorporating an optical analyser device and also a digital system for the recording of multiple images. The detector system was built to explore a wide range of possibilities including in-line electron holography, the observation and recording of diffraction patterns from very small specimen regions (having diameters as small as 3Å) and the formation of both bright field and dark field images by detection of various portions of the diffraction pattern. Experience in the use of this system has shown that sane of its capabilities are unique and valuable. For other purposes it appears that, while the principles of the operational modes may be verified, the practical applications are limited by the details of the initial design.
Functions Of TEM Incorporated With Personal Computer and Frame Memory
Authors: Nomura S. , Isakozawa S. , Kamimura S.
Published: June 2020

It is expected that a computer aided TEM which incorporates a frame memory system and a TV camera, provides many useful functions which have not yet been made available. We constructed an experimental TEM, shown in Fig. 1, and made some experiments which are described below.

Dual Magnification Display of Specimen Images; If low and high magnification images are displayed at the same time, field selection would be a lot easier. This method has been already established in SEM. In our TEM, this is performed by memorizing the low magnification image in a frame memory, and by controlling the specimen stage by a computer. The CRT displays the low magnification image stored in the memory and a mask which indicates the specimen image area under the high magnification condition. The operator moves the mask and sets it on the area of interest. Then electron microscope magnification is changes from low to high. The stage is moved automatically, corresponding to a new masked position. We see a high magnification image on the fluorescent screen and also on the other CRT. The low magnification image stored in the memory is not changed, and the next specimen area for high magnification is readily chosen by moving the mask.
Specimen Preparation of Near Surface Ion Irradiated Samples
Authors: Russell K. F. , Horton L. L.
Published: June 2020

Beams of heavy ions from particle accelerators are used to produce radiation damage in metal alloys. The damaged layer extends several microns below the surface of the specimen with the maximum damage and depth dependent upon the energy of the ions, type of ions, and target material. Using 4 MeV heavy ions from a Van de Graaff accelerator causes peak damage approximately 1 μm below the specimen surface. To study this area, it is necessary to remove a thickness of approximately 1 μm of damaged metal from the surface (referred to as “sectioning“) and to electropolish this region to electron transparency from the unirradiated surface (referred to as “backthinning“). We have developed electropolishing techniques to obtain electron transparent regions at any depth below the surface of a standard TEM disk. These techniques may be applied wherever TEM information is needed at a specific subsurface position.
Mechanical Prethinning and Thinning of Unique Materials For TEM
Authors: Haltom C. P.
Published: June 2020

Several “prethinning” or mechanical dimpling devices are available for routine dimpling of ceramics prior to ion milling. Mechanical erosion thinning, to form a dimple or depression where the resulting specimen thickness is ∼50 μm reduces milling time. The shortened milling time is advantageous in many ways since some materials are quite friable and extended milling time often deteriorates the specimen. In other cases, where specimens of fine powder are mixed with an epoxy binder, the shortened milling time preserves the binder's integrity. Another advantage is that some specimens can be mechanically thinned to electron transparency thus eliminating artifacts which are sometimes introduced by ion milling.
Ultramicrotomy in the Analysis of Magnetic Recording Media
Authors: Narayan P. B.
Published: June 2020

Particulate magnetic recording media is widely used to store information in computer memory applications. The media consists of submicron-size gamma iron oxide and alumina particles held together by a binder resin onto a substrate (mylar for floppy disks and aluminum for rigid disks). The electrical properties of media depend on the physical characteristics (like size and shape), dispersion and orientation of iron oxide. Well- dispersed and optimum-sized alumina improvies wear resistance of the relatively soft media. Transmission electron microscopy (TEM), with its excellent spatial resolution, is found to be very useful in analyzing media. Ultramicrotomy can be conveniently used to prepare cross-sections of the media for TEM study The major advantage of ultramicrotomy is that it provides a large amount of uniformly thin area relatively quickly.
Combined Use of Structure Imaging and Microanalysis in Structure-Composition Analysis By A 400-KV High-Resolution Analytical Electron Microscope
Authors: Bando Yoshio , Kitami Yoshizo , Mitcmo Mamoru
Published: June 2020

One of the limitations in the use of the conventional analytical electron microscope (AEM) with lower voltages of 100 to 200 kV is based on its poor image resolution compared to normal transmission electron microscope. Because of this, it is difficult to carry out structure determination by directly observing individual atom arrangements in crystals. However, a new AEM with an intermediate voltage of 400 kV (JEM-4000EX, TEMSCAN) is fully capable of high resolution observation under equipment of an energy dispersive x-ray spectrometer (EDS) and an electron energy loss spectrometer (EELS). The present paper shows crystal structure images of sialon polytypes and corresponding EDS and EELS spectra, and describes the usefullness of combined techniques of structure imaging and microanalysis in structure-composition determination.
Microstructural Study of Diamond Deformed Under High Pressure and Temperature
Authors: Koch E. F.
Published: June 2020

Because of the extremely rigid lattice structure of diamond, generating new dislocations or moving existing dislocations in diamond by applying mechanical stress at ambient temperature is very difficult. Analysis of portions of diamonds deformed under bending stress at elevated temperature has shown that diamond deforms plastically under suitable conditions and that its primary slip systems are on the ﹛111﹜ planes. Plastic deformation in diamond is more commonly observed during the high temperature - high pressure sintering process used to make diamond compacts. The pressure and temperature conditions in the sintering presses are sufficiently high that many diamond grains in the sintered compact show deformed microtructures.

In this report commercially available polycrystalline diamond discs for rock cutting applications were analyzed to study the deformation substructures in the diamond grains using transmission electron microscopy. An individual diamond particle can be plastically deformed in a high pressure apparatus at high temperature, but it is nearly impossible to prepare such a particle for TEM observation, since any medium in which the diamond is mounted wears away faster than the diamond during ion milling and the diamond is lost.
A Practical Method of Determining Grain Boundary Crystallographic Parameters Using Microdiffraction
Authors: Randle Valerie , Ralph Brian
Published: June 2020

To relate the observed structures in grain boundaries to the theoretical models requires a knowledge of the main parameters describing the crystallography across the boundary (e.g. 1). A number of methods have been described for determining the axis/angle of misorientation, ℓ/Θ and the plane of the boundary using conventional electron diffraction SADP (e.g. 2-3). In a recent study a distinction between the migration characteristics of special and general boundaries was made (4). A precise determination of the boundary parameters requires the manipulation of data from Kikuchi patterns (e.g. 3) and, in SADP these are only excited from thicker portions of the foil.

Microdiffraction has a number of significant advantages for such studies (e.g. 5) as demonstrated here. The results come from a major investigation of the interaction between precipitate dispersions and grain boundaries (6). The alloy chosen is Nimonic PE 16 (the heat treatments are given in the figure captions). Figure 1 is a bright field image of a low angle grain boundary pinned by carbide particles.
Observations of Precipitates In 95PB-5SN Solder
Authors: Frear Darrel , Morris J. W.
Published: June 2020

The electronic packaging of integrated circuit chips has been cited as the limiting factor in the performance and reliability of high speed data processing units. A very important part of the package is in the first level where solder bonds the IC chip to a ceramic carrier. The most commonly used first level solder is 95Pb-5Sn. The importance of this solder connection instigated the following fundamental study of the microstructure of 95Pb-5Sn and its precipitates.

The alloy was melted in vacuum at 400°C using 99.9% pure Pb and Sn. The ingot was allowed to cool and age for a few days at room temperature. TEM 3mm foils were cut and mechanically thinned down to 4 mil thickness. After aging at room temperature the solder is considered to be in its equilibrium state, no further changes in microstructure are observed.
Star-Shaped Multiply Twinned Gold Particles
Authors: Karlen A. , Thölén A.
Published: June 2020

Small submicron size particles have been extensively studied in the electron microscope. These particles have mainly been produced by evaporation in an inert gas, where the particles form a smoke or in vacuum, where the particles grow on a substrate held at temperature. The most common defect in these particles are twins, which essentially are of two different kinds. The first type of twins, which is usually found on one family of lattice planes are frequent in gas evaporated particles; the second type of twins build up the so called multiply twinned particles (MTP) and are more common when the evaporation occurs in vacuum onto a heated substrate. The multiply twinned particles can be regarded as five or twenty regular tetrahedrons, glued together. Although this structure is not space filling, internal strains can make it so. The shape of multiply twinned particles has recently been discussed, where also finer details in their structure were resolved.
Electron Energy Loss Spectroscopy at 5Å Spatial Resolution
Authors: Isaacson M. , Scheinfein M.
Published: June 2020

One of the ultimate goals of electron energy loss spectroscopy within the electron microscope is to be able to obtain the electronic structure of interfaces at near atomic resolution. Though this goal has not yet been achieved, there has been considerable effort devoted to elemental composition at high spatial resolution using ELS (eg. References 1-3). In this paper we wish to present initial measurements made across different types of interfaces that show core and valence shell electron energy loss spectra changing within an 8Å spatial scale across the interface.

All the measurements have been performed using a modified dedicated STEM (VG Scientific HB-5) equipped with beam blanking facilities, digital control and a wide-gap aberration connected energy loss spectrometer. The details of this instrument have been described elsewhere (4). The main point to be noted is that the incident illumination half angle was 7.5mrad for these experiments and the full width at half maximum of the probe was 4.6Å (measured). With these optical conditions, 90% of all the incident beam current is contained within a diameter of 9.0Å (5). For beam sensitive materials, the recording dose was kept to less than 1/3 the dose for observable sample degradation.
Excited State Lifetime Measurement By EEL-CL Coincidence
Authors: Ahn C.C. , Krivanek O.L.
Published: June 2020

The lifetime of an excited state can be measured by detecting both the excitation (by EELS) and the de-excitation (by catho- doluminescence), and measuring the delay between the two events. We have adapted this technique for the measurement of lifetimes in an electron microscope.

The experimental set-up is shown in Fig. 1. The arrival time and the energy loss of single electrons is monitored by the EELS (Gatan 607), and the arrival time and wavelength of single photons is monitored by the CL spectrometer. Pulses corresponding to the two events are fed to a time-to-amplitude converter (TAC), which outputs a variable height pulse proportional to the delay between the events. If no second (stop) pulse is detected within a preset time interval, the TAC recognizes a “false start”, does not output anything, and starts looking for a “start” pulse again. Since the count rate in the CL channel was typically 10 to 100 times weaker than in the EEL channel, we minimized the false starts by using the CL signal as the start pulse and the EEL signal, suitably delayed, as the stop pulse. This yields a “reversed time” spectrum, but minimizes the dead time of the electronics.
Immunoelectron Microscopic Localization of Intermediate Filament Vimentin in Neuroblastoma Cells: Methods
Authors: Feng-Chen K.C. , Wang H. , Yorke G. , Browning E.T. , Roisen F.J.
Published: June 2020

The cytoskeleton of many cell types contains three prominent filamentous elements: intermediate filaments; actin-containing microfilaments and microtubules. Five antigenically distinct classes of intermediate filaments (IFs) have been identified on the basis of their protein subunit composition: keratin; desmin; glial fibrillary acidic protein; neurofilament triplet protein and vimentin. Although substantial progress in identifying and determining the functional roles of these filamentous proteins has been made with immunof1uorescent techniques, relatively little has been accomplished with immunoelectron microscopy. Previously, it has been difficult to simultaneously preserve ultrastructural detail, maintain antigenicity and ensure antibody penetration into dense cytoskeletal structures. The non-ionic detergent, Triton X-100 has been used, prior to or after fixation, to facilitate macromolecular access to deeply localized antigens. This extraction procedure maintains antigenicity as mirrored by immunofluorescence microscopy. The present study presents a reliable method that preserves dense filamentous cellular organelles and permits immunocytochemica1 localization of vimentin in cultured neuroblastoma cells.
Three-Dimensional Immunoelectron Microscopy of Yeast Cells by a New High-Resolution Replica Method
Authors: T. Hirano , Yamaguchi M. , Hayashi M. , Sekiguchi Y. , Tanaka A.
Published: June 2020

A plasma polymerization film replica method is a new high resolution replica technique devised by Tanaka et al. in 1978. It has been developed for investigation of the three dimensional ultrastructure in biological or nonbiological specimens with the transmission electron microscope. This method is based on direct observation of the single-stage replica film, which was obtained by directly coating on the specimen surface. A plasma polymerization film was deposited by gaseous hydrocarbon monomer in a glow discharge.

The present study further developed the freeze fracture method by means of a plasma polymerization film produces a three dimensional replica of chemically untreated cells and provides a clear evidence of fine structure of the yeast plasma membrane, especially the dynamic aspect of the structure of invagination (Figure 1).
Surface Ultrastructure of Human Ectocervix in Certain Pathological Conditions
Authors: Mukherjee S. , Guha T. , Chakrabarti B. , Chakrabarti P.
Published: June 2020

The cervix is an important organ in reproduction. Its malfunction is frequently a factor for infertility. Ectocervix region does not appear to have received much attention although many studies have been reported on the endocervix. We report here our SEM observations on ectocervix in certain pathological conditions compared to normal ectocervix.

Ectocervix specimens from human females with specific pathological disorders were processed for Scanning Electron Microscopy by conventional method and they were examined in a Philips SEM.

The normal ectocervix is lined by flat layer of squamous epithelial cells with microridges (Fig. 1). These cells are known to be formed from columnar cells through metaplastic transformation. The cells of carcinoma-bearing ectocervix show a disorganised appearance (Fig. 2). In non-malignant tumour surface some cuboidal and few columnar cells were seen (Fig. 3). A cyst appears like an overgrowth on the surface of the squamous epithelium (Fig. 4). In ulcerated ectocervix a marked reduction of epithelial cells are observed (Fig. 5); the cells are devoid of microridges and, the large polygonal cells, as observed in normal tissues, have somehow acquired comparatively small hexagonal shape
Coronary Artery Trauma Following Syngeneic Heterotopic Heart Transplantation: A Model For Atherogenesis in the Rat
Authors: Van Valen Ronald G. , Melden Mary Kay , Saunders Robert N. , Handley Dean A.
Published: June 2020

A wide variety of experimental models are used to develop atherosclerosis in animals. Many researchers have applied the basic premise that repetitive injury to the vascular endothelium (i.e. chemical, immunological, metabolic or physical) can induce a neointimal proliferative response. There are, however, relatively few experimental models available to evaluate coronary artery atherogenesis in small laboratory animals. We investigated the rat syngeneic heterotopic heart transplant model to produce coronary artery (CA) injury. By mechanical design, reversed blood flow to the aortic sinus would provide localized turbulence with resultant endothelial cell damage in the coronary ostia of the grafted heart.
Electron Microscopy in the Study of Natural Phytoplankton Assemblages
Authors: Sicko-Goad Linda
Published: June 2020

Although the use of electron microscopy and its varied methodologies is not usually associated with ecological studies, the types of species specific information that can be generated by these techniques are often quite useful in predicting long-term ecosystem effects. The utility of these techniques is especially apparent when one considers both the size range of particles found in the aquatic environment and the complexity of the phytoplankton assemblages.

The size range and character of organisms found in the aquatic environment are dependent upon a variety of physical parameters that include sampling depth, location, and time of year. In the winter months, all the Laurentian Great Lakes are uniformly mixed and homothermous in the range of 1.1 to 1.7°C. During this time phytoplankton productivity is quite low.
Applications of Electron Microscopy to Plant Pathology
Authors: Klomparens-Baker Karen , Roberts David L.
Published: June 2020

With the publication of the first micrograph of tobacco mosaic virus by Ruska and his collaborators in 1939, the electron microscope, specifically the transmission microscope (TEM) was launched as a useful tool in plant pathology. While both the TEM and scanning EM (SEM) are used in basic and applied plant science research in studies of morphological and structural development, their use in plant pathology extends to diagnosis of diseases, studies on the subcellular interactions of plant hosts, pathogens and their vectors, morphological development of pathogens, effects of environmental factors, ultrastructural effects of disease control measures and detection of such disease agents as viruses and virions which are unresolvable with other methods. In addition, recent advances in EM analytical techniques such as energy dispersive x-ray analysis, cytochemistry and immunologic labeling have lent themselves well to new applications in basic plant pathology research.
A Scanning Electron Microscopic Study of Pro-Vascular Cellular Morphology in Chaetophora Incressata
Authors: Hotchkiss A. E. , Hotchkiss A. T. , Apkarian R. P.
Published: June 2020

Multicellular green algae may be an ancestral form of the vascular plants. These algae exhibit cell wall structure, chlorophyll pigmentation, and physiological processes similar to those of higher plants. The presence of a vascular system which provides water, minerals, and nutrients to remote tissues in higher plants was believed unnecessary for the algae. Among the green algae, the Chaetophorales are complex highly branched forms that might require some means of nutrient transport. The Chaetophorales do possess apical meristematic groups of cells that have growth orientations suggestive of stem and root positions. Branches of Chaetophora incressata were examined by the scanning electron microscope (SEM) for ultrastructural evidence of pro-vascular transport.
Cerebral Tubuloreticular Inclusions In Reye's Syndrome
Authors: Harb Joseph M. , Murphy Jerome V. , Tang Thomas T.
Published: June 2020

Introduction

Tubuloreticular inclusions (TRI) were first reported in patients with herpesvirus encephalitis or systemic lupus erythematosus (SLE). TRI are abnormal subcellular structures which consist of fine irregularly branched, anastomosing tubules within cisternae of endoplasmic reticulum. TRI have also been reported in blood lymphoreticular cells, vascular endothelial cells, mesenchymal cells, and epithelial cells in a variety of clinical conditions which include SLE and other autoimmune diseases, congenital immunodeficiency, lymphoproliferative disorders, neoplasms, neurodegenerative disorders, T-cell leukemia, and acquired immune deficiency syndrome (AIDS). We have recently reported an association of TRI with Reye's syndrome (RS). The inclusions were found in peripheral leukocytes of two unrelated patients with RS following a prodromal influenza respiratory infection. Subsequent to those studies we have retrospectively examined biopsy material from earlier cases of RS, and have identified TRI in the capillary endothelial cells from brain biopsies of three RS patients. The purpose of this report is to present these observations and to discuss the association of TRI with RS.
Ultrastructural Identification of Ferritin in Seminoma
Authors: Siew S.
Published: June 2020

In recent years, investigation of the pathophysiology of malignant neoplasia has led to the identification of the presence of products known as tumor markers, which are characteristic of certain tumors. The demonstration of increased levels in the serum of such specific tumor markers is of high diagnostic significance and their decrease after appropriate treatment is important in the monitoring of therapy. In non-seminomatous testicular germ cell tumors, the most reliable tumor markers are alpha-fetoprotein and human chorionic gonadotrophin, as their levels are raised in about 75% cases. However, in pure seminomas, their levels are not raised in the serum and their presence cannot be demonstrated in the tissue. Serum ferritin levels are reported to be increased in more than 80% of patients with seminomas. Immunohistochemical studies have shown the presence of both acidic and basic isoferritins in the majority of testicular seminomas. This investigation extends these observations to the ultrastructural level of elemental analysis by the application of energy dispersive x-ray microanalysis.
The Congenital Nephrotic Syndrome: A Review and Case Report
Authors: Price George , Cerezo Lizardo
Published: June 2020

The congenital nephrotic syndrome (CNS) is a rare form of neo-natal nephropathy that generally occurs within the first three months of life, and is characterized by proteinuria, placentamegaly, and retarded intrauterine growth. Proteinuria in infants can result from a variety of other causes such as congenital infections (syphilis, CMV, etc.), mercury intoxication, and minimal change lesion, but CNS is the only nephrotic syndrome of neonates that is unresponsive to immunosuppressive drugs.

This syndrome was first defined and extensively studied in Finland where this condition was estimated to occur in 1 per 10,000 births, and was found to be an expression of an autosomal recessive inheritence. It has also occured in children without a history of Finnish ancestry.

The prognosis for these children is poor, most often resulting in death by the fourth year of life unless a renal transplant is received. A study of 17 transplants in children with CNS reported a 71% graft survival rate over a two year period with no recurrence of nephrotic syndrome in any transplants.
Preparation of the Buffy Coat From Small-Volume Blood Samples For Ultrastructural Study
Authors: Mitchell M. J. , Mirro E. J. , Black H. E. , Schwartz E.
Published: June 2020

Electron microscopic examination of peripheral blood is a valuable technique in toxicological research. Blood can be collected for examination several times during a toxicological study. Compound-induced cellular changes detected in peripheral blood cells prior to the terminal necropsy may be an early indication of potential compound-related toxicity.

The routine use of small rodents in toxicological studies presents a problem; the amount of blood available at interim collections is minimal. The following technique has been refined for the purpose of examining leukocytes in small blood samples (1 cc or less). Leukocytes are concentrated so that a maximal number per sample can be examined.
High-Resolution Stereo Electron Microscopy of Neurofilaments and Alzheimer Type Paired Helical Filaments
Authors: Wisniewski H.M. , Wen G.Y.
Published: June 2020

To learn about the ultrastructural similarities and dissimilarities between the Alzheimer's paired helical filaments (PHF) and normal neurofilaments, we developed a new method to cut the plastic embedded block. We call the sections cut by this new method supra-ultrathin sections. To obtain supra-ultrathin EM sections, a selected area of the tissue block was first trimmed to a size about 0.25 mm2 to reduce the sectioning pressure between the knife and the tissue block. The tissue was sectioned as thin as possible. The interference color of the sections was almost as transparent as the water surface. The thicker sections with different interference colors were removed by picking up with hair tip so that all of the sections floating on the water were of same or similar thickness. A saturated solution of uranyl acetate in 50% ethanol was used to maximize the contrast of these supra-ultrathin EM sections on uncoated grids.
Neurofilaments and Paired Helical Filaments
Authors: Metuzals J.
Published: June 2020

It has been demonstrated that the neurofibrillary tangles in biopsies of Alzheimer patients, composed of typical paired helical filaments (PHF), consist also of typical neurofilaments (NF) and 15nm wide filaments. Close structural relationships, and even continuity between NF and PHF, have been observed. In this paper, such relationships are investigated from the standpoint that the PHF are formed through posttranslational modifications of NF. To investigate the validity of the posttranslational modification hypothesis of PHF formation, we have identified in thin sections from frontal lobe biopsies of Alzheimer patients all existing conformations of NF and PHF and ordered these conformations in a hypothetical sequence. However, only experiments with animal model preparations will prove or disprove the validity of the interpretations of static structural observations made on patients. For this purpose, the results of in vitro experiments with the squid giant axon preparations are compared with those obtained from human patients. This approach is essential in discovering etiological factors of Alzheimer's disease and its early diagnosis.
Structural modifications in H-implanted and laser desorbed Si
Authors: Zheng P. , Saint-Jacques R.G. , Boivin R. , Terreault B.
Published: June 2020

Near-surface microstructural modifications of silicon which occur in hydrogen ion implantation and classical thermal desorption have already been reported. Our work is related to desorption using an intense and pulsed laser. The particularity of this technique is only the surface (≈2μm) heated. We report results of transmission electron microscopy (TEM) of the microstructural modifications in H-implanted and laser desorbed silicon.

Silicon [001] oriented has been implanted with 5 keV H to a dose of 1017cm-2 and desorbed with a ruby laser (694.3 nm, 30 ns). It received an energy of 0.9 J.cm-2 and its surface temperature reached the melting point. This sample was totally desorbed as indicated by mass spectroscopy and checked by Elastic Recoil Detection. Plan-view [001] and cross-sectional [110] TEM samples were mechano-chemically thinned (10% HF + 90% HNO3). TEM dynamic imaging conditions (imaging vector g=220, w=0) were used to observe the defects.
Incommensurate modulated phases of the NbxTa1-xTe4 charge density wave system
Authors: Ritchie S. , Bennett J. C. , Prodan A. , Boswell F.W. , Corbett J.M.
Published: June 2020

A continuous sequence of compounds having composition NbxTa1-xTe4; 0 ≤ x ≤ 1 have been studied by electron diffraction and microscopy. Previous studies have shown that the end members of the series, TaTε4 and NbTε4 possess a quasi-one-dimensional character and exhibit charge density wave (CDW) distortions. In these compounds, the subcell structure is tetragonal with axes (a × a × c) and consists of the metal atoms (Nb or Ta) centered within an extended antiprismatic cage of Te atoms. At room temperature, TaTε4 has a commensurate modulation structure with a 2a × 2a × 3c unit cell. In NbTε4, an incommensurate modulation with × ∼ 16c axes is observed. Preliminary studies of the mixed compounds NbxTα1-xTε4 showed a discontinuous jump of the modulation wave vector commensurate to incommensurate when the Nb dopant concentration x, exceeded x ≃ 0.3, In this paper, the nature of the compositional dependence of is studied in greater detail and evidence is presented for a stepwise variation of . This constitutes the first direct evidence for a Devil's staircase in CDW materials.
Chemical-shift analysis of O Kα by EPMA color-mapping method for BiSrCaCuO superconductive specimen
Authors: Takahashi H. , Okumura T. , Seo Y. , Kabaya A. , Nielsen C.
Published: June 2020

The chemical shifts of x-ray spectra are now frequently observed with EPMA (Electron Probe Microanalysis). The conventional method of chemical-shift analysis with EPMA is to compare the peak shapes and peak positions of standard spectra with those of unknown spectra. We reported that O-Kα peak shapes detected by using a TAP (Thallium acid phthalate) crystal reflect their crystal structures. Fig. 1 shows these O-Kα spectral peaks. In the present study, concerning the BiSrCaCuO superconductor made by the sintering method, it was observed that the O-Kα spectra of several kinds of phases reflected their crystal structures. Moreover, it is now possible to observe these chemical shifts of spectra by using the color mapping method in EPMA.
HREM in solid-state chemistry and crystallography
Authors: Kihlborg Lars , Sundberg Margareta , Svensson Gunnar
Published: June 2020

High-resolution electron microscopy has had a great impact on solid state chemistry. The possibility it offers of directly imaging the structure of solids has made it an unvaluable complement to conventional diffraction methods. Disorder and extended effects have become accessible to observation, superstructures, structural modulations and microphases can be identified and particles down to nanometer size can be studied. Combined with electron diffraction and x-ray microanalysis it is a powerful tool for phase analysis, giving guidance to synthesis of new compounds. Under certain conditions even chemical reactions can be studied in situ at atomic resolution. Numerous examples in be found in the fields of high-temperature superconductors, zeolites, ferroelectrics and solid state ionics.
SPECTRA: A program for processing electron images of crystals
Authors: Schmid M.F. , Dargahi R. , Tam M. W.
Published: June 2020

Electron crystallography is an emerging field for structure determination as evidenced by a number of membrane proteins that have been solved to near-atomic resolution. Advances in specimen preparation and in data acquisition with a 400kV microscope by computer controlled spot scanning mean that our ability to record electron image data will outstrip our capacity to analyze it. The computed fourier transform of these images must be processed in order to provide a direct measurement of amplitudes and phases needed for 3-D reconstruction.

In anticipation of this processing bottleneck, we have written a program that incorporates a menu-and mouse-driven procedure for auto-indexing and refining the reciprocal lattice parameters in the computed transform from an image of a crystal. It is linked to subsequent steps of image processing by a system of data bases and spawned child processes; data transfer between different program modules no longer requires manual data entry. The progress of the reciprocal lattice refinement is monitored visually and quantitatively. If desired, the processing is carried through the lattice distortion correction (unbending) steps automatically.
Effect of matrix crystallinity on the characteristics of the interfacial layer in SiC fiber-reinforced Si-Al-O-N composites
Authors: Shin Hyun-Ho , Berta Yolande , Park Chan , Speyer Robert F.
Published: June 2020

Glass or glass-ceramics have been used as matrix materials for fiber reinforcing by the slurry infiltration process, followed by hot pressing. These matrices have been used for two major reasons: (i) They oxidize the SiC fiber to form a C-rich interfacial layer between the fiber and matrix during hot pressing (2SiC(s) + O2(g) = 2C(s) + 2SiO(g)). Such carbon-rich layers cause low fiber-matrix interfacial shear strength resulting in high composite fracture toughness. (ii) A low viscosity matrix is required to minimize fiber damage during hot pressing. In the present study, the Si2N2O - AI2O3 system was used as a new host material for Nicalon SiC fiber: it has a more refractory nature and is able to provide a liquid phase (with the presence of a sintering agent, e.g., A12O3, CaO, etc.) to avoid fiber damage during densification. This matrix system can also provide oxygen to form a C-rich interphase. In this paper, the effect of matrix crystallinity on the interfacial characteristics is described.