bluuebunny/crossref_metadata_2025 huggingface dataset:
Localization of micropores in polymer films
Authors: Geymayer W.F. , Grasenick F.
Published: June 2020

For studying corrosion problems, for the understanding of osmotic processes or generally for the investigation of reactions inside porous polymer films the knowledge of the frequency and the size of the pores as well as the registration of the course of penetrating pores is of high importance for the determination of the active pore-volume.

In most of these processes at least one of the reactants is a fluid being in contact with the diaphragm through which it reacts with the medium on the other side. The fluid often begins to swell the polymer layer, a process that may even be necessary to develop the osmotic properties of the membrane.

Thus it was an interesting problem, to find a way of detecting the pores in a possibly swollen organic diaphragm without altering it. Drying the specimens completely disturbs the original conditions, chemical dehydration with subsequent soaking the pores with a suitable monomer-mixture causes strong changes of the sensitive material by uncontrolled shrinkag.
Degradation of cellulose with high voltage electrons
Authors: Tucker P. A. , Hersh S. P. , Berry G. M. , Kerr N. , Mcelwain D. M.
Published: June 2020

As part of a larger study of the degradation of polymers, cotton cellulose is being intentionally degraded with high voltage electrons. The initial results were reported earlier (1). Because of the implications of this study to the electron microscopy of beam sensitive materials, special attention is being given to relating these studies to electron microscopy.

Generally, the microscopist's main, and perhaps only, information on specimen degradation is that provided by diminution of the electron diffraction pattern. It will be shown in this paper that even though specimen diffraction patterns are only slightly altered, the mechanical and chemical properties are vastly changed.

To produce degraded fabrics having strength losses of 75% or more, cotton fabrics were exposed to radiation doses of 50 and 100 Mrad at 550 kV in an electron accelerator manufactured by High Voltage Engineering Corporation. Properties of such cotton fabrics before (i.e., control) and after exposure to 50 and 100 Mrad dosages are presented in Table I.
Applications of scanning transmissionelectron microscopy in materials science
Authors: Bovey P.E. , Wardell I.R.M. , Williams P.M.
Published: June 2020

Following the work of Crew and colleagues, considerable interest has been generated during recent years in the technique of scanning transmission electron microscopy (STEM). Employing a tungsten field emission source, a simple two lens electron optical column is capable of producing a beam of electrons incident on a thin sample with a gaussian FWHM of 5Å or less, which may be scanned to produce an image modulated in brightness by the transmitted electron intensity. It is then generally accepted that for a suitable detector geometry, such an image is formally equivalent on reciprocity grounds to that produced in a conventional TEM. Such equivalence is an essential prerequisite for the materials scientist who wishes to exploit the high brightness probe in STEM for analytical applications, but not at the expense of image clarity and ease of interpretation.

Thus, figure 1, shows conventional dark field (la) and weak beam dark field (lb) images recorded for dislocations in a thin foil of an Al/ Zn/Mg alloy, following orientation of the foil using rocking beam selected area diffraction and direct viewing of the non-scanned diffraction pattern on a fluorescent screen introduced into the column of the HB5 dedicated STEM.
Cathodoluminescence studies of CaF2 crystals in the SEM
Authors: Sluev V.I. , Saparin G.V. , spivak G.V. , Orlov J.N. , Bogevolnov V.E. , Ivanov L.N. , Karelin V.V.
Published: June 2020

Calcium fluoride is a base of single crystals with and without impurities and dust-shaped substances which are widely used in optical industry,laser technique,dosimetry,analitical chemistry etc.Central points of the study of processes which take place into the excited CaF2 crystals are the problem concerning to the nature and structure of irradiation centers.We studied the transfer of energy by ions of impurity in the CaF2 crystals,the problem of minimum concentration detected by the SEM ana also the dependence of spatial CL resolution upon dimensions of substance particles.

Single crystals of CaF2 activated by europium and manganese and grown by the Bridgman method in an HF atmosphere in graphite crucibles have been investigated in the paper.Some consentration series of single crystals were synthetized: CaF2:Eu(0 to 5%):Mn(0 to 6%).We observed the CL topography of crystal surface and also measured the CL intensity vs. activator concentration at room temperature.These experiments were realized with help of cutoff optical filters placed before input window of the photomultiplier in the SEM.
Effects of backscattering on the resolution of scanning Auger Microscopy
Authors: Janssen A.P. , Venables J.A.
Published: June 2020

We have previously shown that the combination of a UHV SEM with a field emmission gun and a CMA for Auger detection is a valuable tool for surface microanalysis /1,2 3/, and we have demonstrated 30nm resolution using conventional N'(E) detection /4/. Although Auger images can be produced in some circumstances with the resolution of the beam diameter, the size of the analysis volume is influenced by backscattered electrons, and this resolution limit has not previously been experimentally determined. In the present preliminary experiments we have observed Auger line scans across abrupt chemical boundaries as a function of incidence angle, ø, and beam energy, Ep. These intensity profiles show reasonable agreement with Monte Carlo calculations /5, 6, 7, 8/ of the spatial distribution of backscattered electrons. For near-normal incidence, most of the Auger current will be emitted from within the primary beam area.

A polycrystalline tungsten surface was flashed clean by electron bombardment heating and 2-5pm diam
Prediction of X-ray spatial resolution for SEM and STEM specimens using Monte Carlo methods
Authors: Faulkner R.G.
Published: June 2020

Determinations of spatial X-ray resolution in conventional microanalysis in electron probe microanalysers where the beam is perpendicular to a smooth surface are now quite straightforward. However, SEM's and STEM'S are becoming increasingly used methods for performing microanalysis. The specimen arrangement for this sort of work often involves both inclined beam and detector geometries. Under these conditions X-ray correction constants have to be altered due to the changed average path length for the emerging X-rays. The spatial resolution and correction constants peculiar to the new geometry can be physically studied using a Monte Carlo computer method which simulates the trajectories of many electrons as they interact with the specimen.

Another attempt to predict resolution and effective take-off angle using single electron scattering theory has been made for thin films. This over estimates the X-ray source size at large foil thicknesses and under estimates at small foil thicknesses. Experimental methods have been devised utilising edges and small, spherical particles.
Interaction between small particles of cobalt, iron and nickel
Authors: Hansson I. , Tholen A.
Published: June 2020

A growing interest has recently been shown in small (< 100 nm) metal particles. Such particles are conveniently made by evaporation in an inert gas atmosphere (see eg. 1,2) and the average particle size is empirically found to increase both with pressure and evaporation temperature.

A detailed study was presented earlier on the interaction between single particles of gold (3). The surface energy was found to be the driving force for the whole series of possible adhesion events which include elastic deformation with strain fields visible in the electron microscope (4), plastic deformation with twinning, relative particle rotation and sliding. Nobody has, however, convincingly reported at which position relative to the evaporation source and at what temperature the particle formation and interaction occur. It is the aim with this investigation to start elucidating these processes by using various ferromagnetic materials with different Curie temperatures. These particles have then, in a way, a memory of the actual processes.
Development of substructure in 1100 aluminum during cold rolling
Authors: Rohr D.L. , Hecker S.S.
Published: June 2020

The plastic response of metals at very large plastic strains is of considerable interest for practical and academic reasons. The question of the existence of a saturation stress remains largely unanswered because most experiments are not carried out to sufficiently large strains. In this paper we report our preliminary findings on the development of substructure in 1100 aluminum during rolling to reductions of 99.8%. This is part of a comprehensive study of microstructure and mechanical response of metals to large uniaxial and biaxial deformations.

Commercially pure (1100) aluminum plates, annealed at 500°C, were rolled at room temperature from various starting thicknesses to a final thickness of 0.127 mm in a 2-high laboratory rolling mill. Sheets with final reductions ranging from 9.1 to 99.8% were examined by transmission electron microscopy. Thin foils were prepared directly from the 0.127-mm thick sheets by electropolishing with a 50cc-50cc-2cc HNO3-CH3OH-HCl solution in a jet polisher.
Dynamic recrystallisation during creep—a comparison between magnesium and quartz
Authors: Burrows S.E. , Humphreys F.J. , White S.H.
Published: June 2020

Quartz is one of the most abundant minerals in the Earth's crust and field evidence suggests that it is the weakest component of many rock types during deformation. It is essential that the mechanical behaviour of the mineral is understood if geological deformation processes are to be modelled and it is clear that TEM provides one of the means of determining the fundamental mechanisms of flow. The well known difficulties encountered in the experimental deformation of polycrystalline aggregates of the mineral have meant that correlation between structures found in experimentally and naturally deformed quartz has not proved satisfactory. TEM studies by several workers (l,2)have shown that naturally deformed quartz contains dislocation structures similar to those produced in metals and ceramics during creep and hot-working. Results reported in the metallurgical literature (3)have been used to explain geological observations. A series of metallurgical experiments has been carried out as an aid to interpreting the dislocation substructures observed in the naturally deformed mineral.
Investigation of second phase particles in Aks-doped tungsten by TEM, SEM and atom probe microanalysis
Authors: Beaven P.A. , Chandrasekharaiah M.N. , Miller M.K. , Toll J.R.F. , Williams P.R. , Smith G.D.W.
Published: June 2020

Tungsten wire used in the production of coiled lamp filaments is usually stabilised against creep by“AKS Doping”. In this process, small additions of Al, K and Si compounds are made to the original tungsten oxide powder prior to reduction, sintering and fabrication. The final drawn wires contain long strings of ultra-fine second phase material, from which rows of stable voids develop when the material is annealed at high temperatures. These voids stabilise the tungsten microstructure by impeding the lateral migration of grain boundaries. It has recently been shown that the voids contain potassium, but the role of the other dopant elements remains unclear. Small solid alumina particles have been found after dissolving doped wires, and mullite crystals have also been reported, but these observations seem inadequate to explain the apparent interaction between the various dopant species in commercial wires. A number of observations of very small solid particles in doped material have also been reported by Field-Ion Microscopy (FIM), e.g. by Meyrick and the present authors but no direct microanalytical investigation has previously been reported.
Combined TEM, FIM, atom probe analysis of a nickel based superalloy
Authors: Beaven P.A. , Delargy K.M. , Miller M.K. , Smith G.D.W.
Published: June 2020

We have recently reported the first combined use of electron microscopy (TEM), field ion microscopy (FIM) and Atom Probe microanalysis for the study of alloy element partitioning between the γ and γ' phases in a nickel-based superalloy, IN939 (l). The distribution of the major alloying elements Co, Cr, Al, and Ti was determined, and the ordered structure of the γ' phase was investigated directly by monitoring the nature of the ions field evaporated from successive atom layers of a superlattice plane. In the present paper, we report several extensions to this work, including investigation of the ultra-fine secondary precipitates formed during the final low temperature stage of heat treatment of the alloy, and a study of the detailed composition of the primary carbide phase.

The alloy studied was a cast, high-chromium superalloy, supplied by Inco (Europe) Ltd. Research Laboratories. The composition of the alloy (in atomic %) is as follows.
Electron microscopy of niobium and tantalum hydrides
Authors: Schober T.
Published: June 2020

Nb, Ta and V are prototype substances for the study of the endothermic reactions of H with metals. Such metal-hydrogen reactions have gained increased importance due to the application of metal-hydrides in hydrogen- und heat storage devices. Electron microscopy and diffraction were demonstrated to be excellent methods in the study of hydride morphologies and structures (1). - Figures 1 and 2 show the NbH and TaH phase diagrams (2,3,4). EM techniques have contributed substantially to the elucidation of the structures and domain configurations of phases β, ζ and ε (1,4). Precision length measurement techniques of distances in reciprocal space (5) recently led to a detailed understanding of the distortions of the unit cells of phases ζ and ε (4). In the same work (4) the existence of the new phase η was shown. It is stable near -68 °C. The sequence of transitions is thus below 70 %.
Cryofixation of suspensions and tissues by propane-jet freezing and high-pressure freezing
Authors: Müller Martin , Moor Hans
Published: June 2020

During the last few years, several techniques for the rapid freezing of thin aqueous layers of cells and tissues have been developed and successfully applied to various biological questions (spray-freezing, propane-jet freezing, metalmirror-freezing, plunge-freezing, high pressure freezing). For practical work, techniques where the biological material (mainly suspensions) is sandwiched between two metal platelets are most favourable, because the frozen sandwiches are easily freeze-fractured, freeze-substituted or freeze-dried. In addition, the thickness that is sufficiently well frozen (vitrified or in the microcrystalline state) is greater in a sandwiched sample than in a specimen cooled only from one side (1). Heat can be extracted from the specimen sandwich either by controlled rapid plunging into a suitable coolant (2) or by shooting the coolant simultaneously from opposite directions onto the specimen surface (propane-jet) (3).
A scanning electron microscopic method for assessing surface topography of bladders
Authors: Tarnowski Betty I. , Schonbaum Gregory R.
Published: June 2020

Neither light microscopy nor transmission electron microscopy lend themselves to an accurate assessment of focal changes of epithelium: both techniques are limited by sampling procedures. The same limitation, however, does not apply to scanning electron microscopy (SEM) (1,2) which permits statistically meaningful analyses on a larger number of samples. The usefulness of such an approach was explored in our studies on the induction of damage to rat urothelium by cyclophosphamide (3,4) and its prevention by adjunct therapy with 2,3-dimercaptopropane sulfonate (DMPS). Portions of the bladder were sampled from the dome, central region and trigone and the tissue was prepared for SEM by dehydration in acetone, followed by critical point drying and gold coating. SEM analyses were performed in a two-step procedure using a Novascan scanning electron microscope at low (20X) and high (100X) magnifications.
Ultrastructure of two neoplasms in culture compared with original biopsies
Authors: Harb Joseph M. , Casper James T. , Piaskowski Vlcki
Published: June 2020

The application of tissue culture and the newer methodologies of direct cloning and colony formation of human tumor cells in soft agar hold promise as valuable modalities for a variety of diagnostic studies, which include morphological distinction between tumor types by electron microscopy (EM). We present here two cases in which cells in culture expressed distinct morphological features not apparent in the original biopsy specimen. Evaluation of the original biopsies by light and electron microscopy indicated both neoplasms to be undifferentiated sarcomas. Colonies of cells propagated in soft agar displayed features of rhabdomyoblasts in one case, and cultured cells of the second biopsy expressed features of Ewing's sarcoma.
The value of electron microscopy in the resolution of pediatric diagnostic problems
Authors: Harb Joseph M.
Published: June 2020

The electron microscope is a valuable tool which is becoming more widely used in diagnostic applications as an adjunct to surgical pathology and histopathology. Because of the resolution and magnification capabilities of electron microscopes, it is possible to document at the sub-cellular level morphological features and organelles which may not be detectable by light microscopy. Electron microscopy (EM) has been used extensively for tumor diagnosis and has proved of increasing value in the resolution of a wide variety of diagnostic problem areas, including hematologic disorders and neoplasms, hepatic, renal, muscle, and nerve disorders, and identification of metabolic storage products and infectious agents. The electron microscope is indlspensible for those diseases in which demonstration of characteristic organelles is specific for differential diagnosis.
MP26 is a lens junctional protein: Analysis with monoclonal antibodies
Authors: Johnson Ross , Sas Jane , Nelson Catherine , Schik Sue , Quade Brad , Frenzel Beth , Sas Daryl
Published: June 2020

Investigators with interests in cell junctions, and gap junctions in particular, have been intrigued over the last 5-10 years by the extensive junctional specializations found in the lens. Attention has focused on the suggested role of MP26 as the major protein component. The fundamental question has been whether the abundant junctions seen with thin-section or freeze-fracture analyses correspond to lens “gap junctions.” That is, do these cell surface specializations between lens fiber cells provide for the direct cell-to-cell movement of small molecules? Unfortunately, we still lack a definitive answer to the question. For some investigators, enthusiasm waned when protein analysis uncovered no homology between MP26 and a major liver gap junction protein. However, we have much to learn about the nature and role of the lens junction.
Alignment of low-dose STEM images of unstained macromolecules
Authors: Hainfeld J. F. , Furcinitti P. S. , Wall J. S.
Published: June 2020

Several studies of molecular structure have successfully employed computer techniques to align images of single particles. Image processing software packages (e.g., P. R. Smith's MDPP system and J. Frank's SPIDER system) have also been developed to facilitate this work. Due to the low contrast and high beam damage rate involved in the use of unstained specimens, most single particle (i.e., non-crystalline) image alignment has been of negatively stained specimens. The scanning transmission electron microscope (STEM), which has a linear transfer function at high resolution rather than the oscillating one inherent to CEMs, operationally overcomes these limitations by providing low dose, high contrast images of unstained material with high collection efficiency.
Investigation of biogenic magnetite particles by high-resolution electron microscope
Authors: Matsuda T. , Endo J. , Osakabe N. , Tonomura A. , Arii T.
Published: June 2020

In 1975, Blakemore found aquatic bacteria that swim along earth's magnetic lines of force [1]. They have permanent magnets of iron-rich fine particles within them. Such particles were found by Mössbauer analysis to consist of magnetite in the case of magnetospirilla [2]. In addition, Towe et al confirmed by electron diffraction that the particles were crystalline [3]. The purpose of the present investigation is to determine the crystal and magnetic structure of these particles by both high-resolution lattice imaging and electron holography; however only the former is reported here.

Magnetotactic bacteria were gathered in a fresh-water pond. The specimens were peanut-shaped, and approximately 3um in length. Transmission electron micrographs, such as that shown in Fig. 1, reveal that approximately 30 fine particles are aligned within each bacterium.
Combined application of monoclonal antibody to human la antigens and avidinblotin-peroxidase staining method in immunoelectron microscopy
Authors: Feng-Chen K.C. , Chen B.F. , Ng A.K.
Published: June 2020

Immunological detection of cellular and tissue antigens have been based on the widely used original enzyme labeled antibody method or the unlabeled antibody, peroxidase-anti-peroxidase (PAP) method. Recently, an improved immunoenzymatic technique for light microscopy using the avidin-biotinperoxidase complex (ABC) system was developed for cell and tissue staining, and found to be superior to the PAP technique in terms of sensitivity and specificity. The application of the ABC method in immunoelectron microscopy (IEM), however, has not been extensively evaluated. This study demonstrates that the ABC method is suitable for localizing specific cellular antigen at the ultrastructural level with monoclonal antibody (MAb), the production of which by somatic cell hybridization is now a well established procedure.
A side-entry cold stage for low-dose high-resolution studies at 1 MeV
Authors: Pawley James B.
Published: June 2020

Low-dose studies of unstained biological macromolecules such as the purple membrane have usually been carried out at 100 kV. There are reasons to believe that on relatively thick samples such studies could be carried out more effectively at 1 MeV (1). These reasons include a slight reduction in radiation sensitivity (2), a reduction of multiple scattering on thicker samples and a larger lens geometry for a given instrumental transfer function. The larger geometry leads to greater depth of focus, which is particularly important on tilted samples, and more space in the lens gap for the introduction of a tilting cold stage. We have earlier reported on various improvements to the Madison HVEM to facilitate high-resolution low-dose studies (3). These include an optimized TV viewing system, a minimal exposure system (4), an improved focus control (5) and a superior photographic film for recording low-dose images at 1 MeV (6). All that was lacking was a low-temperature stage with sufficient stability to permit us to take advantage of the 4-5 x reduction in radiation sensitivity below 130° C (7). Such a stage is described below.
Identification of calcium oxalate crystals in dried or fixed tobacco leaf
Authors: Baliga Vicki L. , Counts Mary Ellen
Published: June 2020

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.

Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.
Formation of paired helical filaments in Alzheimer's disease
Authors: Metuzals J. , Clapin D. F. , Montpetit V.
Published: June 2020

Information on the conformation of paired helical filaments (PHF) and the neurofilamentous (NF) network is essential for an understanding of the mechanisms involved in the formation of the primary lesions of Alzheimer's disease (AD): tangles and plaques. The structural and chemical relationships between the NF and the PHF have to be clarified in order to discover the etiological factors of this disease. We are investigating by stereo electron microscopic and biochemical techniques frontal lobe biopsies from patients with AD and squid giant axon preparations. The helical nature of the lesion in AD is related to pathological alterations of basic properties of the nervous system due to the helical symmetry that exists at all hierarchic structural levels in the normal brain. Because of this helical symmetry of NF protein assemblies and PHF, the employment of structure reconstruction techniques to determine the conformation, particularly the handedness of these structures, is most promising. Figs. 1-3 are frontal lobe biopsies.
Oxygen precipitation in carbon-containing silicon
Authors: Tsai H.L. , Carpenter R.W. , Peng J.D.
Published: June 2020

The effect of carbon on oxygen precipitation in heat-treated silicon has been of current research interest. It has been suggested that carbon impurity may act as nucleation center for oxide precipitates (1). On the other hand, evidence indicates that the precipitate density does not necessarily increase with the carbon concentration (2). In this paper, we report the results of the TEM study of oxide precipitates in the carboncontaining CZ silicon under various heat-treatment conditions.

The (111) wafers which were cut from several positions along a silicon ingot were initially annealed at 750°C for various times ranging from 0 to 100 h and were second-step annealed at 1050° C for 16 h or 11 h. Some (100) wafers were preannealed at 750°C for 100 h and then annealed at 1050°C for 0 to 8 h. Initial oxygen concentrations in the as-grown silicon crystals were in the range of (1.4-1.7) x 1018 cm-3 and carbon concentrations were (2-9) x 1016 cm-3.
The influence of InSb substrate surface quality on the MBE growth of CdTe films
Authors: Greggi J. , Wood Susan , Farrow R. F. C. , Takei W. J. , Shirland F. A. , Noreika A. J.
Published: June 2020

Large areas of high quality, single crystal CdTe are desirable as substrates for the subsequent growth of Hg1-xCdxTe for infrared applications. However, bulk crystal growth of CdTe invariably results in microtwins as well as other lattice defects such as boundaries, dislocations, and Te precipitates. Molecular beam epitaxial growth (MBE) of heteroepitaxial CdTe on lattice matched substrates of InSb (|∆a|/a≲5x10-4 at 25°C) has resulted in films of good quality as determined by X-ray techniques. This study reports on a TEM characterization employing cross-sectional techniques of MBE grown heteroepitaxial CdTe on InSb (001) substrates. CdTe films of high structural perfection can be prepared, but this perfection depends critically on substrate surface quality and, therefore, substrate cleaning procedures.
Examination of optical fibers by the luminescent method in the scanning electron microscope (SEM)
Authors: Wells Oliver C. , Bailey Philip J.
Published: June 2020

Light is transmitted along the central core of an optical fiber by total internal reflection at the interface with the surrounding layer. Here, we describe a method by which the optical properties of a cross-sectioned fibre can be studied by means of the luminescent image in the scanning electron microscope (SEM).

The sample is prepared by depositing a thin cathodoluminescent layer over the end of a broken or cross-sectioned optical fiber. A thin conducting layer is then deposited to prevent charging. The far end of the fiber is optically coupled to a photomultiplier. During examination in the SEM, the sample is scanned by a fine electron beam, which gives a localised source of light on the surface of the sample at the point of impact of the beam. The quantity of light that is transmitted along the fiber to the photomultiplier determines the brightness of that particular pixel in the recorded image.
Quantitative measurement of magnetization distribution in domain walls of 1.2%Fe-Co by differential-phase-contrast STEM
Authors: Tsuno K. , Sekiguchi T. , Watanabe D. , Kersker M.
Published: June 2020

When a ferromagnetic specimen is observed under diffraction mode of an electron microscope, central spot splits according to the magnetization direction in the magnetic domain of the specimen. Amount of shift of the diffraction spot is proportional to the intrinsic magnetization and specimen thickness. Magnetic domain can be seen under the image mode by covering one of the spots with an objective aperture.

If electron intensity of split diffraction discs are detected by the two adjacent detectors, one signal is subtracted from the other and the subtracted signal is displayed under the scanning mode, domain image can also be displayed under the STEM mode. This magnetic domain observation technique (differential phase contrast (DPC) STEM) has been investigated by Chapman et al.
Transmission electron microscopy study of an oriented thermotropic liquid crystalline polymer
Authors: Wood B.A.
Published: June 2020

Electron microscopy studies of fibers spun from lyotropic polymer mesophases are far more common in the literature than reports of TEM of thermotropic polymers, but recently publications have appeared reporting oriented electron diffraction patterns and “banding” in TEM images of thermotropic polyesters. Considering the advantages of fiber spinning from the melt, an understanding of the detailed morphology of thermotropic polymers, their ordering in flow fields, and the influence of quenched-in mesomorphic orientation on 3-D crystalline order is desirable. The experimental study described herein utilizes a solution casting technique to produce oriented thin films of a block polyester containing alternating rigid mesogenic and flexible spacer groups (Fig. 1a).
Enhanced contrast SEI/TEM of polymer membranes
Authors: Sawyer L. C.
Published: June 2020

Specimen preparation for the characterization of polymers requires special handling to ensure that the in situ structures are observed. In the case of polymer membranes the situation is more difficult than usual as these thin, porous films are delicate and may collapse upon drying. Standard embedding and microtomy are often not possible due to this soft, collapsable texture. When microtomy is successful the resulting sections usually exhibit poor contrast due to their low atomic number. Scanning electron microsopy (SEM) of fractured cross-sections often reveals collapsed textures. Surface analysis also has limited resolution. The subject of this paper is to describe the enhanced contrast methods developed for both the secondary electron imaging (SEI) and transmission electron microscopy (TEM) of polymer membranes for three dimensional structure characterization.
Deformation of calcia-stabilized zirconia single crystals
Authors: Voegele-Kliewer C.E. , Mitchell T.E. , Heuer A.H.
Published: June 2020

This study is an investigation of slip in calcia-stabilized zirconia (CSZ) single crystals and the resulting dislocation substructures. CSZ has the high temperature cubic fluorite structure when cooled rapidly to room temperature, but it can be aged in the two phase region to produce either tetragonal precipitates (hypoeutectoid) or ϕ1 precipitates (hypereutectoid). In the present study, the effect of ageing to produce tetragonal precipitates prior to deformation was also examined.
TEM observations on pores in alumina
Authors: Morrissey K. J.
Published: June 2020

Pores play an important part in the microstructural development of ceramic materials such as α-Al2O3. In sintered materials pores are often found at two grain interfaces, grain boundary triple points, and in integranular regions. The separation of pores from grain boundaries in the final stage of sintering results in the isolation of the pores and prevents the material from reaching full density. The process of pore-breakway is an important aspect of the study of grain boundary migration.

This investigation has centered on observing pores in as received polycrystalline α-Al2O3 compacts and thin films of α-Al2O3. This report is part of a larger study on grain boundaries and interfaces in Al2O3. The first observations of pores in this study were made on an α-Al2O3 sample which had been extruded and sintered, MgO was used as the densification aid. Pores can affect the migration of a boundary by pinning it, moving with the boundary, or the boundary may move past the pore.
Effect of additives on the polytypic transformation of pressureless sintered silicon carbide
Authors: Shinozaki S. , Donlon W. T. , Peters C. R. , Williams R. M. , Juterbock B. N.
Published: June 2020

The influence of metallic aluminum (Al) and silicon (Si) additives on the polytype distributions in silicon carbide (SiC) has been investigated. Tajima and Kingery and Shinozaki and Kinsman have shown, respectively, that 4H polytype becomes predominant when SiC materials are heat-treated in Al- or Si-rich environments. Quantitative x-ray diffraction analysis of polytype distributions has revealed that when β-SiC powder with an Al addition is sintered near 1950°C, the 15R polytype increases considerably and the 4H polytype becomes predominant above 1950°C. The correlations between polytype distributions in SiC grains and grain boundary chemistry have been studied using analytical electron microscopy.
A low-voltage field-emission column with a Schottky emitter
Authors: Tuggle D.W. , Watson S.G.
Published: June 2020

The advantages of a room-temperature field emission (FE) cathode for forming a sub-micrometer high current, low voltage electron probe, namely small energy spread, high brightness and a small virtual source diameter are somewhat offset by the high vacuum required in the electron gun and the fluctuations in the emission current. The thermal-field mode of operation, with its relaxed vacuum requirements and relatively stable emission current has the disadvantage of an increased energy spread of emission, which degrades the spatial resolution of a focused beam. A Schottky point emitter, similar in geometry to a field emitter but with a larger radius, can achieve high current density by use of a low work function surface operating at elevated temperature. In the Schottky emission (SE) mode, electron transmission over the top of the potential barrier rather than tunneling through the barrier is the emission mechanism.
Substructures in deformed Fe-15 Ni-0.8 C austenite
Authors: Sachdev Anil K. , Shea M. M.
Published: June 2020

In a recent study, the mechanical behavior of an Fe-15 Ni-0.8 C austenite was determined at various strain rates and temperatures. An important finding of this study was the formation of intense shear bands during deformation at temperatures much greater than which bore no resemblance to the common morphologies of martensites. There is much disagreement in the literature regarding the mechanism of band formation and the associated substructure. These bands have been reported to be fine BCC martensite particles or laths delineating slip bands or thin twins in the austenite matrix. The purpose of the present work was to determine by transmission electron microscopy and diffraction the substructure of the fine bands and to attempt to clarify the various interpretations. For comparison, the substructure produced at a lower deformation temperature was also evaluated where the martensite was known to have the normal strain-induced morphology.
SEM and EDS study of magnetic effects on electroplating of Cr-Fe alloys
Authors: Cousins C.A. , Dash J.
Published: June 2020

Some preliminary results of the effects of magnetic fields on high current efficiency electrodeposition of CR-FE alloys were reported previously (1). For the present experiments, high purity Ni cathodes and Pb anodes were used. The cathode current density was 0.25 amps/cm2 and the cathode and anode were positioned vertically and parallel to each other and to the horizontal magnetic field (B). Two series-wired water-jacketed electrolytic cells were used. One cell was located between the pole pieces of an electromagnet and the other was approximately 30 cm away. The plating time was 30 minutes for each experiment and the current efficiency varied from 51.8 to 53.9% for the deposits in Fig. A. The initial cell temperature was 40°C.
Structural determination of amorphous Ti-Ni alloys
Authors: Pelton A. R. , Moine P. , Sinclair R.
Published: June 2020

Amorphous Ti-Ni alloys may be prepared by a variety of techniques, including: liquid quenching, ion implantation, electron irradiation, and vapor synthesis. Each of these techniques involves fundamentally different atomic processes with concomitant different effective quench rates. Since quench rates affect the degree of structural order, it is conceivable that a variety of metastable configurational states may thus result. Radial distribution functions (RDF’s) from diffraction experiments are a generally accessible probe for statistical characterization of amorphous alloys, and hence, a useful tool to compare amorphous structures. However, not all of the amorphization methods are capable of producing sufficient quantities of material required for x-ray or neutron scattering. Therefore, the purpose of this paper is to report the preliminary results from a comparative structural investigation of Ti-Ni alloys by x-ray and electron diffraction.
Lattice misfit by convergent-beam electron diffraction - Part II: Energy measurement
Authors: Lin L. S. , Walsh J. M.
Published: June 2020

Geometry measurement described in Part I required photographing the CBED and measuring the height of the triangle Pγ, Pγ' and the folz ring radius Rγ/γ'. These manipulations can be eliminated by an energy measurement approach first described by Steeds. Using the small angle approximation to Bragg's law gives

For a cubic material with lattice constant a, Eq. (1) can be restated as

Small changes in the accelerating voltage will change the position of holz lines and are related to changes in lattice constant as in Eq. (4)
Translation symmetries in convergent-beam electron diffraction
Authors: Buxton B. F. , Shannon M. D. , Eades J. A.
Published: June 2020

For crystallographic studies in the transmission electron microscope the “ideal” sample is considered to be a parallel sided slab, oriented perpendicular to the electron beam, cut from perfect crystal. Such a slab does not, in general, have the full symmetry of the crystal from which it has been cut. As a result, there arises the question as to whether the symmetry observed in the diffraction pattern reflects the symmetry of the slab or that of the infinite, perfect crystal. For the most part this matter is clear but there is one class of situation that has been (and perhaps still is) the subject of some debate.

If the infinite crystal contains glide planes or screw axes for which the corresponding translation is not parallel to the slab, then, strictly speaking, the slab does not have these symmetries. Normally, however, in transmission electron diffraction patterns, symmetry features that result from the presence of these symmetry elements are observed (although Goodman asserts that they should not be).
Singularities in moiré patterns
Authors: Sawhill H. T.
Published: June 2020

Terminating fringes in moiré patterns were first reported in 1957 and optical analogues have historically been used to attribute their presence to lattice dislocations. In this investigation, a criterion for singularities in moire patterns is developed by establishing a direct relation between phase changes and displacement fields between overlapping crystals. Two misoriented crystals imaged under strong 2 beam diffraction conditions are shown schematically in Fig. 1. The resulting intensity takes the form of eq. 1, where F, G and x0 are constants (different for bright and dark field) g is the reciprocal lattice vector of crystal 1 (2 beam condition) and vector R describes the displacement of crystal 2 lattice positions relative to crystal 1 in the interface. The resulting intensity is described by a set of cosine fringes, with bright fringes corresponding to the loci of points for which cos (2πg.R) = 1 (with x0 = 0). This condition is satisfied whenever R is a lattice vector of crystal 1; solutions are position vectors of lattice 2 with associated displacement vectors equal to crystal 1 lattice vectors.
K-shell cross sections for analytical electron microscopy
Authors: Zaluzec Nestor J.
Published: June 2020

There has during the last few years been a renewed interest in the calculation of ionization cross-sections for use in AEM-based x-ray analysis, due to the fact that modern AEM's can operate up to accelerating potentials of 400 kV. In this regime relativistic effects are considerable and the extrapolation of the “accepted” microprobe-based formulae to these levels is questionable and the relativistic Bethe equation is the most appropriate formulation.
A complex network of “snake-like tubules” revealed by the NADPase cytochemical reaction in the acinar cell of pancreas
Authors: Beaudoin A.R. , Grondin G. , Lord A. , Pelletier M.
Published: June 2020

We have recently described the ultrastructural localization of NADPase activity in the exocrine pancreas of rat. The enzyme was found in the intermediate saccules of the Golgi apparatus, in dense bodies and lysosomes but was absent from zymogen granules. A very intense reaction was noticed in a peculiar structure which was termed “Snake-Like Tubule” (SLT). The purposes of the present study were firstly to delineate SLT distribution in the acinar cell and secondly to define any possible relationship or association with other cellular organelles.

NADPase cytochemical reaction was performed on the pancreas of adult Sprague Dawley rats. Small lobules were excised and fixed for 50 min, at 4°C, in 2% glutaraldehyde buffered with 0.1M cacodylate at pH 7.2. Lobules were rinsed several times with the same buffer containing 570 sucrose and cut with a Mcllwayn tissue chopper. Sections were washed several times with buffer and incubated for 2 hr at 37°C in the following medium: 4mM NADPH; 40mM sodium acetate buffer, pH 5.0; 4mM lead acetate and 5% sucrose.
β-Mannosidosis: Myelin and oligodendrocyte lesions in brain and spinal cord
Authors: Lovell Kathryn L. , Jones Margaret Z.
Published: June 2020

Caprine β-mannosidosis, an autosomal recessive defect of glycoprotein catabolism, is associated with a deficiency of tissue and plasma -mannosidase and with tissue accumulation and urinary excretion of oligosaccharides, including the trisaccharide Man(β1-4)GlcNAc(βl-4)GlcNAc and the disaccharide Man(β1-4)GlcNAc. This genetic disorder is evident at birth, with severe neurological deficits including a marked intention tremor, pendular nystagmus, ataxia and inability to stand. Major pathological characteristics described in Nubian goats in Michigan and in Anglo-Nubian goats in New South Wales include widespread cytoplasmic vacuolation in the nervous system and viscera, axonal spheroids, and severe myelin paucity in the brain but not spinal cord or peripheral nerves. Light microscopic examination revealed marked regional variation in the severity of central nervous system myelin deficits, with some brain areas showing nearly complete absence of myelin and other regions characterized by the presence of 25-50% of the control number of myelin sheaths.
Phagocytosis studied by acridine orange-crystal violet fluorescent staining
Authors: Musclow C.E. , Farkas-Himsley H. , Kormendy A. , Goldner M.
Published: June 2020

Bacteria can be examined by fluorescent microscopy, using the flurochrome dye acridine orange (AO) which distinguishes between viable (green) and nonviable (red-orange) organisms. (Fig. 1) The colour changes when increased amounts of AO intercalate with the phosphate sugar backbone of DNA, as it becomes denatured. This metachromatic shift can be used in phagocytosis studies to record viability and monitor killing of ingested bacteria. To avoid counting extracellular bacteria, crystal violet (CV) is used subsequently to quench the fluorescence in the external environment. At supravital concentration (0.05%) CV enters the prokaryotic cells, but will not penetrate the eukaryotic phagocytes. This study establishes the reliability of counting viable and nonviable cells by AO fluorescence in comparison to conventional methods; studies the kinetics of phagocytosis by polymorphonuclear cells (PMN) and monocytes; optimizes the test conditions; evaluates a phagocytic base line in normal individuals and determines if deliberate interference of some phagocytic parameter, such as inhibition of killing, can be recognized by AO-CV assay.
An ultrastructural investigation of urethane-induced lung tumors in strain-A mice
Authors: Gunning W.T. , Stoner G.D. , Maklinson A.M. , Goldblatt P.J.
Published: June 2020

The cellular origin of chemically-induced lung tumors in mice has not been completely resolved. Brooks (1968) reported that most urethane-induced lung tumors in strain A mice were derived from type II alveolar epithelial cells. In contrast, Kauffman (1981) observed that the majority of clinically- induced lung tumor in Swiss mice were derived from Clara cells of the bronchiolar epithelium. Preliminary results from the present study are in agreement with those of Kauffman (1981) in that most urethane-induced lung tumors in strain A/J mice appear to be derived from Clara cells.

Eight week-old female A/J mice were injected I.P. with 1000 mg/kg of urethane. Twelve months after injection, the mice were sacrificed by cervical dislocation and their lungs fixed in buffered 4% formalin - 1% glutaraldehyde, introduced via the trachea. Tumors in the right lung were identified grossly, catagorized according to size (<1-.5, 1.6-5, and >5 mm in diameter) and location (centrolobular or peripheral), and prepared for both light and electron microscopy.
Effects of aculeacin A and papulacandin B onCandida albicans
Authors: Bozzola J. J. , Mehta R. J.
Published: June 2020

Aculeacin A1and papulacandin B2are closely related antimycotic agents that interfere with the synthesis of alkalai-insoluble β 1-3 glucan in the cell wall ofCandida albicans, Saccharomyces cerevisiaeandGeotrichum lactis. The chemical structures of both agents contain a long-chain fatty acid, and both agents are strongly inhibitory toC. albicansand some other fungi while having negligible activity against bacteria or protozoa. Earlier studies involving light microscopy of aculeacin A treated cells revealed rounded, distorted cells aggregated in clumps. The sole TEM micrograph of aculeacin A treated cells showed invaginations and globular bodies associated with plasma membranes.