bluuebunny/crossref_metadata_2025 huggingface dataset:
SEM of non-coated hepatocellular cytoskeleton of perfused livers
Authors: French S.W. , Benson N.C. , Davis-Scibienski C.
Published: June 2020

Previous SEM studies of liver cytoskeletal elements have encountered technical difficulties such as variable metal coating and heat damage which occurs during metal deposition. The majority of studies involving evaluation of the cell cytoskeleton have been limited to cells which could be isolated, maintained in culture as a monolayer and thus easily extracted. Detergent extraction of excised tissue by immersion has often been unsatisfactory beyond the depth of several cells. These disadvantages have been avoided in the present study. Whole C3H mouse livers were perfused in situ with 0.5% Triton X-100 in a modified Jahn's buffer including protease inhibitors. Perfusion was continued for 1 to 2 hours at ambient temperature. The liver was then perfused with a 2% buffered gluteraldehyde solution. Liver samples including spontaneous tumors were then maintained in buffered gluteraldehyde for 2 hours. Samples were processed for SEM and TEM using the modified thicarbohydrazide procedure of Malich and Wilson, cryofractured, and critical point dried (CPD). Some samples were mechanically fractured after CPD.
Calcium oxalate crystal formation in a species of Hyphoderma (basidiomycetes)
Authors: Arnott H. J. , Whitney K. D.
Published: June 2020

Calcium oxalate crystals are often found in association with fungal hyphae. In examining leaf litter samples with the use of scanning electron microscopy, Graustein et al. demonstrated that hyphae of some basidiomycetes are often encrusted with conspicuous calcium oxalate deposits and postulated that these crystals were formed when oxalate released by the fungus precipitated with free calcium ions in the environment. Studies by Arnott and Arnott and Webb, however, showed that at least some calcium oxalate crystals produced by these fungi arose within the fungal cell wall. These studies revealed that the crystals were enclosed within a thin layer of wall material during development, and it was hypothesized that the growth of the crystals is under direct control of the fungal cell.
Substrate influences on explosively crystallized amorphous germanium films
Authors: Hoelke C.W. , Parsons J.R.
Published: June 2020

The structure of amorphous Ge can be most satisfactorily described by a continuous random network model. The basic features of this random network for amorphous Ge are the total absence of translational symmetry combined with tetrahedrally coordinated atoms whose bond angles are as close to the ideal tetrahedral angle of 109° 28’ as possible. Non-crystallinity is achieved through variations in the tetrahedral angle and through relative rotations of adjoining tetrahedra. The local structure is thus well-defined. The medium range structure is, however, subject to debate as a number of physical properties, such as optical absorption and electrical conductivity, have been found to be highly sensitive to deposition conditions and heattreatment. The purpose of the present work was to use the phenomenon of explosive crystallization as a probe to investigate the medium range structure of amorphous Ge. Inhomogeneities in the medium range structure were expected to influence the morphology of the explosively crystallized foils.
Measurements of the range of secondary electrons in low-Z materials
Authors: Muray A. , Isaacson M. , Kirkland E.
Published: June 2020

Previously, calculations of the resolution of SEM secondary electron images due to the escape depth of these electrons utilized Monte-Carlo calculations to simulate the “edge brightness effects” seen in high resolution magnification images obtained with small probe sizes (e.g.,). Similar Monte-Carlo calculations have been made to try to deduce the energy dissipation profiles in PMMA due to secondary electrons. We are trying to develop a simple analytical model which might allow us to get a better feel for the salient features with which the secondary electrons limit the pattern size in microfabrication and spatial resolution in the SEM.

For our initial measurements, we have fabricated the structure shown in figure 1. The thickness of both the PMMA and Si substrate are less than one mean free path for inelastic scattering (of 100 keV electrons) thick. A 10 Å diameter beam of convergence angle of 15 mrad is incident normal to the sample surface.
Cluster-ion bombardment of thin films
Authors: Ledbetter M. C. , Matthew M. , Beuhler R. J. , Friedman L.
Published: June 2020

Energetic cluster ion impact on solid surfaces can be used to deposit large quantities of kinetic energy in small assemblies of atoms in the surface. Extremely high transient pressures and increases in the density of surface atoms are produced by these impact processes. Significant alteration of surface structure is expected. We have investigated the effects of bombardment of thin carbon films with singly charged clusters of argon atoms and protonated water molecules accelerated to energies as high as 300 kV. Clusters were generated in weakly ionized plasmas produced by a corona discharge at atmospheric pressure in helium carrier gas. The singly charged seed ions in this discharge served as nuclei in the expanding gas mixture that was introduced into a high vacuum system through a super sonic nozzle and a differentially pumped skimmer.
Filler material in medical-grade silicones
Authors: Greer R. T.
Published: June 2020

Medical-grade silicone rubber is a widely utilized biomaterial. As is the case for most rubbers, fillers are used to give additional strength to the polymer. The nature of the filler is of interest in the development, fabrication and improvement of medical devices where blood and tissue compatibility may be altered by submicroscopic structure and phase distribution. The medical-grade silicone rubbers are of two types, heat-vulcanizing and room-temperature-vulcanizing (RTV).

The filler used in heat-vulcanizing types is fumed silica of a small particle size of the order of 0.03 µm and smaller (0.007 µm; 0.012 µm; Cab-0-Sil®, Cabot Corp., Boston, MA 02110). It is made by a vapor phase process (hydrolysis of silicone tetrachloride at 1100° C ), producing a colloidal amorphous silica (SiO2). It is generally classified as a fumed silica due to its production at a high flame temperature. Fume-process silicas give the highest degree of reinforcement of silicone rubber compared with finely divided silicas made by a wet process (aerogels), or with diatomaceous earth.
Cleavage of layer crystals
Authors: Hines R. L.
Published: June 2020

Layer crystals such as graphite, molybdenite and mica have a variety of uses in electron microscopy when lamella can be easily prepared with clean surfaces, uniform thickness, high crystal perfection and tolerable waviness. The most common use of thin crystals is as a featureless support for high resolution microscopy. Crystals can also be used as phase plates and to reduce radiation damage. Crystals have long been used to display high resolution images and can be used to accurately characterize electron microscope operational parameters.

Crystals for any of the uses described above can in principle be prepared by any technique although their usefulness may be severely limited by nonuniform thickness, surface contamination and sparse fields. Crystals prepared by cleavage with pressure sensitive tape give useful supports with simple equipment and require less than 20 minutes of preparation time for the crystal lamellae mounted on one grid.
AEM investigation of ZrO2 solid solution formation in ZrO2/mullite composites
Authors: Dinger T. R.
Published: June 2020

Zirconia (ZrO2) is often added to ceramic compacts to increase their toughness. The mechanisms by which this toughness increase occurs are generally accepted to be those of transformation toughening and microcracking. The mechanism of transformation toughening is based on the presence of metastable tetragonal ZrO2 which transforms to the monoclinic allotrope when stressed by a propagating crack. The decrease in volume which accompanies this transformation effectively relieves the applied stress at the crack tip and toughens the material; microcrack toughening arises from the deflection of a propagating crack around sharply angular inclusions.

These mechanisms, however, do not explain the toughness increases associated with the class of composites investigated here. Analytical electron microscopy (AEM) has been used to determine whether solid solution effects could be the cause of this increased toughness. Specimens of a mullite (3Al2O3·2SiO2) + 15 vol. % ZrO2 were prepared by the usual technique of mechanical thinning followed by ion beam milling. All observations were made in a Philips EM400 TEM/STEM microscope fitted with EDXS and EELS spectrometers.
High resolution observations of short-range ordering in disordered Au4Mn alloys
Authors: Tanaka Nobuo , Ohshima Ken-ichi , Harada Jinpei , Cowley J.M.
Published: June 2020

Observation of short range ordered (SRO) state in disordered binary alloys is the interesting topic in the point of order-disorder transition. The observation and analysis have been made with X-ray and neutron diffraction techniques which can give the SRO-parameters. These techniques, however, give only the information of an averaged structure. The ordering process is localized, so direct observations in atomic level by high resolution electron microscopy is needed for the detailed analysis.

In the present study, disordered Au4Mn alloys were investigated with high resolution electron microscopy for the analysis of the origin of the characteristic SRO diffuse scattering (Fig. 1). The material was prepared by quenching and thinned by electrolytic polishing for microscopic observations. The specimen was observed along <120> direction by JEOL-200CX electron microscope (E=200keV).
High-resolution electron microscopy of disordered LiFeO2
Authors: Tanaka Nobuo , Cowley J.M.
Published: June 2020

The disordered structure of lithium ferrite (α-LiFeO2) has been investigated in X-ray and electron diffraction techniques. The characteristic short range order (SRO) diffuse scattering was commonly interpreted by the clustering model. The SRO state can be described by interconnecting two kinds of clusters (Fig. 1). Alternatively, it may be interpreted in terms of microdomains of some ordered structures.

In the present study, the specimen was investigated with high resolution electron microscopy and optical diffraction technique. The techniquescould give the information about the SRO state in a direct way. The material investigated was α-LiFeO2in the form of a fine powder dispersed on a holey carbon grid.

Fig. 2 shows electron diffraction patterns of the specimen in the <001> and <110> observing directions. The locus of the diffuse scattering does not exactly fit with the formula, cosπh + cosπk + cosπℓ = 0, which was derived from SRO arrangement of Li and Fe ions inside the clusters. This fact suggests the existance of “inter-cluster” ordering.
Low voltage SEM, Auger, and XPS of surface contaminants
Authors: Brandis E.K. , DeStafeno J. , Flitsch R. , Landenberger R.
Published: June 2020

Scanning electron microscopy has been successfully applied in nearly all fields of scientific endeavor. In most cases, the desired information was obtained operating the SEM with beam energies ranging from 10-30 KeV. Recently, with the advent of SEMs specially designed for operation at low beam energies, it became practical to perform analysis with low beam energies. In the field of semiconductors, to avoid charging the surface by the incident beam, the use of selected low beam energies became mandatory for circuit testing and photoresist line width measurements. In the field of materials analysis, occasional use of low electron beam energies was made, in which surface details were highlighted. With lower beam energies, the penetration of the electron beam is reduced and the interaction of the beam with surface features becomes more pronounced. In the past, widespread utilization of this mode of scanning electron microscopy was not practical because most SEMs had a severely reduced spatial resolution at beam energies of less than 5 KeV.
Stroboscopic testing of LSIs with LVSEM
Authors: Todokoro H. , Yoneda S. , Yamaguchi K.
Published: June 2020

Recently, the low-voltage scanning electron microscope (LVSEM) has become the center of wide interest. This is because the SEM has become an indispensable instrument in the field of semiconductor production, where packing density is increasing and device geometry is shrinking to a few microns or less. However, application of the SEM in the semiconductor industries presents two serious problems: (i) electron radiation damage to transistor functions and (ii) charge-up of electrons on insulators. Various reports concerning electron radiation damage have been published (1,2,3), and it has been found that electron energy must be less than 2 kV to minimize radiation damage. Such low energy also avoids the charge-up effect. However, it is quite difficult to get a fine probe at such low energy due to insufficient source brightness and electron optical aberration.
The response to heating of dislocation structures in zircaloy-2 irradiated to high neutron fluences
Authors: Gilbert R.W.
Published: June 2020

Zirconium alloys have good neutron economy and corrosion resistance in high temperature water and this has led to extensive usage of these alloys in CANDU reactors. However, during neutron irradiation, dimensional changes occur in zirconium components due to the rearrangement of atoms knocked from their lattice sites by fast neutrons. This “irradiation growth” may limit the lifetime of some reactor components and an understanding of the variables that control the process is of commercial importance.

It is believed that dislocations and dislocation loops act as sinks for the displaced atoms and thus control the direction and magnitude of the strain through their Burgers vector. A knowledge of the irradiation-induced dislocation structure is therefore required.
Microstructure of boride-containing melt-spun superalloys
Authors: Hall E. L. , Huang S.-C.
Published: June 2020

It is well known that trace amounts of boron (∼0.01w/o) have a beneficial effect on the creep properties of polycrystalline Ni-base superalloys, generally attributed to the segregation of boron to grain boundaries. Larger alloying additions of boron lead to the formation of discrete boride phases, and improvements in strength and creep behavior can result from a fine uniform dispersion of boride particles. However, during conventional solidification of alloys with significant amounts of boron, the boron tends to segregate and form blocky borides at cell or grain boundaries, which eliminates the particle strengthening effects and may actually degrade mechanical properties due to strain localization. Rapid solidification of boron-containing superalloys, on the other hand, may lead to the nucleation and growth of a fine dispersion of borides since segregation of boron will be reduced. This paper presents the results of using analytical electron microscopy to study the microstructures of rapidly-solidified boron-doped Ni-base superalloys.
The effect of different depths in the foil on the image contrast of dispersed precipitates
Authors: Hu C.T. , Allen C.W.
Published: June 2020

The precipitate particles with similar size are often observed to exhibit quite different contrast in a dark-field TEM micrograph, as shown in Figure 1. The accuracy of particle size determination will be influenced by this variation of contrast. In order to faithfully determine the diameter of second phase precipitates, the causes of this different contrast needed to be investigated. The change of image contrast due to the relaxation of coherency strain of precipitates has been discussed in other work. This study try to found out the influence on the image contrast by the different particle depths in the foil as well as by the interference with the surface oxide.

If the differing contrast of similar size particles is caused by the different particle depths in the foil, then the change of relative depths by straight inverting the specimen and imaging under the same diffraction condition would cause the variation of the particle image contrasts.
Background subtraction in STEM energy-loss mapping
Authors: Leapman R.D. , Gorlen K.E. , Swyt C.R.
Published: June 2020

The determination of elemental distributions by electron energy loss spectroscopy necessitates removal of the non-characteristic spectral background from a core-edge at each point in the image. In the scanning transmission electron microscope this is made possible by computer controlled data acquisition. Data may be processed by fitting the pre-edge counts, at two or more channels, to an inverse power law, AE-r, where A and r are parameters and E is energy loss. Processing may be performed in real-time so a single number is saved at each pixel. Detailed analysis, shows that the largest contribution to noise comes from statistical error in the least squares fit to the background. If the background shape remains constant over the entire image, the signal-to-noise ratio can be improved by fitting only one parameter. Such an assumption is generally implicit in subtraction of the “reference image” in energy selected micrographs recorded in the CTEM with a Castaing-Henry spectrometer.
X-ray diffraction effect on EDX quantitative analysis of crystals
Authors: Tanji T. , Yada K.
Published: June 2020

Analytical electron microscopy with energy dispersive x-ray analyzer (EDX) has been value for the elemental analysis. It has an advantage to be able to analyze the very narrow area of the specimen and is used often for the study of localization of the components. In the case of the quantitative analysis of bulky specimens theoretical approximations for the absorption effect and the fluorescent excitation have been almost established. For thin film specimens spectra obtained by TEM or STEM have only to be corrected on the effect of atomic number (Thin Film Approximation), although for more accurate analysis and for the thickish specimen above-mentioned two effects which, strongly depend on the thickness have to be taken into account. Some reports have shown good agreement with the results of quantitative analysis by EDX and that of chemical analysis, whereas it is observed sometimes that the results obtained are distributed more than several atomic percent.
Characterization of oxide scales on complex alloys using multiple microanalytical techniques
Authors: Sprague J. A. , Singer I. L. , Gossett C. R.
Published: June 2020

The alloys used as coatings to protect gas turbine components from high temperature oxidation and from sulfur-related hot corrosion attack are, in most cases, complex multiphase materials, which form complex oxide scales. A study of the effects of alloy composition and microstructure on the mechanisms controlling oxidation of such a system is greatly aided by the use of complimentary information from several microanalytical methods, each of which has its own strengths and weaknesses.

In investigations of oxide scales, scanning Auger microanalysis (SAM), in conjunction with Ar-ion milling gives semiquantitative composition vs. sputtering time for each of the phases detected. However, since various metals and their oxides can sputter at different rates, only relative depth scales can be obtained. Rutherford backscattering spectroscopy (RBS), on the other hand, provides absolute depth scales and quantitative composition information for the heavier elements in the specimens.
Electron microscopy and zirconium oxidation
Authors: Ploc R.A.
Published: June 2020

Zirconium-based alloys, namely Zircaloy-2 and Zr-2½ wt% Nb are heavily used in the CANDU (Canadian Deuterium and Uranium) system of nuclear energy generation. Although corrosion in heavy water at about 573 K is not a design limiting concern, corrosion does produce hydrogen which can result in hydride formation that embrittles reactor components. About twenty years ago, an effort was initiated at the Chalk River Nuclear laboratories (CRNL) designed to develop an understanding of the physical structure of the oxide films first, on reactor-grade zirconium, then on dilute zirconium alloys, and finally, on reactor materials. A great deal of this investigative work has been performed in the TEM, SEM and in a SAM.
Edge-on TEM studies of oxide scale formation on FeNiCr alloys
Authors: Newcomb S.B.
Published: June 2020

The high temperature oxidation resistance of many commercial alloy systems is often reliant upon the development of a steady state scale via the selective oxidation of one of the alloy constituents. The growth of adherent chromiumrich sesquioxides on iron-chromium alloys, for example, imparts good oxidation resistance although steels of low chromium content (< 13wt%) generally form thick layered scales which may breakdown after extended periods giving rise to accelerated rates of oxidation. The high temperature growth process essentially proceeds thermally activated transport and may involve either the outward diffusion of cations and/or the inward migration of anions. Typically, solid state diffusional transport will take place by lattice diffusion or by transport along grain boundaries so that the overall rate of transport is an inherent property of the oxide structure and composition. Equally, the morphology of the oxide itself will be determined by a variety of kinetic and thermodynamic factors.
Double-tilt FIM specimen holder for JEOL 200CX
Authors: Newkirk J.W. , Walck S.D. , Jones R.H. , Hren J.J.
Published: June 2020

It has long been recognized that combined TEM and FIM analyses provide a powerful analytical combination. Special holders that will accept needle shaped FIM specimens have been built and used by several investigators. However, full advantage of the TEM could not be taken because previous holders have been capable of single axis rotation only--about the specimen direction. Diffraction contrast studies were then limited to a few chance orientations and many analytical questions remained unresolved. A second othogonal tilt axis, of even modest range thus enhances the possibilities considerably. The double tilt holder described here covers the angular range ± 20° on the orthogonal or Y-axis. In addition, the wire specimen can be remounted at any rotated position so that the experimentally accessible range is ± 180°. This combined angular range is sufficient for most diffraction contrast experiments. More to the point, it permits the attainment of a number of two-beam conditions. The JEOL 200CX used here also has a combined EDS and ELS capacity and the FIM is configured as an imaging atom probe (IAP).
Inexact reconstruction: A. The basic method
Authors: Crewe A. V. , Crewe David A.
Published: June 2020

The problem of reconstructing a 3D object from its 2D projections is too well known to require much introduction. Great success has been achieved in a few special cases and in electron microscopy we can refer to the use of regular arrays of molecules or the use of isolated objects having a great deal of internal symmetry, while the case of the generalized object is exemplified by the CAT scan system. Unfortunately this last method is not suitable for electron microscopy because of the large number of projections which would be required.

If we imagine a small object contained inside a cube of N3 resolution elements it would normally require N views containing N2 line projections in order to have enough information for a reconstruction. However, if we make the reasonable assumption that the object is Boolean in nature—by which we mean that it has a uniform density—then the number of required projections decreases considerably.
Formation of single-layer arrays and 6-Angstrom electron imaging of the surface layer protein of Aquaspirillum serpens
Authors: Wu W. H.
Published: June 2020

Aquaspirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits (HP-protein). Buckmire and Murray concluded that a “backing layer”, later identified to be the outer membrane, was required for HP-protein to form 2-d arrays.

We developed a modified procedure of isolation of outer wall fragments. The yield was about 10 times increased, and patches with structured arrays were bigger and more frequent. Large, light arrays of good crystalline order were obtained, with which the optical diffraction patterns always show “handedness” (see Fig. 1); whereas with the dark patches, the optical diffraction patterns appear to be symmetrical. We conclude that the light arrays are real single layer protein arrays.
Pyrolytic carbon filaments and associated catalytic particles formed in steel tubes
Authors: Chen Y. L. , Bradley J. R.
Published: June 2020

Considerable effort has been directed toward an improved understanding of the production of the strong and stiff ∼ 1-20 μm diameter pyrolytic carbon fibers of the type reported by Koyama and, more recently, by Tibbetts. These macroscopic fibers are produced when pyrolytic carbon filaments (∼ 0.1 μm or less in diameter) are thickened by deposition of carbon during thermal decomposition of hydrocarbon gases. Each such precursor filament normally lengthens in association with an attached catalyst particle. The subject of filamentous carbon formation and much of the work on characterization of the catalyst particles have been reviewed thoroughly by Baker and Harris. However, identification of the catalyst particles remains a problem of continuing interest. The purpose of this work was to characterize the microstructure of the pyrolytic carbon filaments and the catalyst particles formed inside stainless steel and plain carbon steel tubes. For the present study, natural gas (∼; 97 % methane) was passed through type 304 stainless steel and SAE 1020 plain carbon steel tubes at 1240°K.
Topographical mapping of ribosomal RNAs in situ by electron spectroscopic imaging
Authors: Boublik M. , Oostergetel G.T. , Frankland B. , Ottensmeyer F.P.
Published: June 2020

Visualization of the in situ location of the individual components of any macromolecular system is important for understanding its assembly, interactions, and function. Ribosomes, which are small cellular organelles involved in protein synthesis are high molecular weight nucleoprotein complexes composed only of proteins and RNAs. This “simple” composition of ribosomes enables us topographical studies directed either towards localization of the individual ribosomal protein and RNA molecules or merely to the determination of the distribution of the protein and RNA moieties within the ribosome and its subunits. We have utilized the recent progress in the development of microanalytical electron spectroscopic techniques, electron energy loss spectroscopy (EELS) in particular, and the unique distribution of the phosphorus atoms on the ribosome (the phosphorus atoms are present only in the structural backbone of the rRNA) for the direct tracing of the RNA molecules in situ.
Evidence of an helicoidal symmetry for rubella virus nucleocapsid
Authors: Alain R. , Berthiaume L. , Trudel M.
Published: June 2020

Rubella virus is presently the only member of the genus Rubivirus of the Togaviridae family (Matthews, 1982). One of the main characteristics of this family is that the symmetry of the nucleocapside is cubical. Electron microscopy shows that rubella virus is a small spherical enveloped particle, 50 to 100 nm in diameter, with a dense core measuring 28 to 30 nm in diameter. Payment et al., in 1975, reported that the core structures are composed of circular subunit, 10 nm in diameter. Morphogenetic studies reveal that core formation coincides with the process of budding (Murphy, 1981).

Rubella virus is composed of three structural proteins E1 (60K), E2 (47K.) and C (33K): E1 and E2 are membrane glycoproteins while C is the nucleoprotein (Trudel et al., 1982). The genome of the virus is a single standed positive RNA.

Upon examination of purified rubella virus by electron microscope, beside whole virus particles we observed in all preparations helicoidal nucleocapsids of variable lenghts, ranging from a few nanometers to as long as 265 nm (Fig. 1). The width of these was evaluated to about 14.7 + 0.9 nm with a helix pitch of 10 nm. They were flexible and fragile, showing rapid denaturation when viral suspensions were kept at room temperature for a few hours.
Cryo-SEM observation of water in leaf intercellular spaces
Authors: Willison J.H.M. , Pearce R.S. , Odense P.H.
Published: June 2020

In the process of transpiration, plants lose water acquired from the soil through pores (stomata) in the leaf epidermis. Beneath the epidermis, within the cortex of the leaf, spaces between cells are interconnected to form a complex lattice. Particularly large spaces, the substomatal cavities, lie beneath the stomata. The pathway taken by transpired water has long been contentious (e.g. Tyree & Yianoulis, 1980), but it is becoming clear that most transpired water passes into the vapour phase within the substomatal cavity. Few direct observations have been made of water in leaf intercellular spaces, the clearest being of large distilled water droplets in substomatal cavities in vivo using light microscopy (Sheriff, 1977). We report here direct observation using cryo-SEM of small convex water droplets lying on wheat leaf air space cell wall surfaces.
Lattice Fringe Imaging Applied to Microstructural Analysis in Materials
Authors: Sande J. B. Vander , Kohlstedt D. L.
Published: June 2020

The formation of lattice fringes from crystalline solids in the transmission electron microscope is a technique which has been used for nearly twenty years as a practical resolution test for these instruments. With the advent of modern transmission microscopes capable of a line-to-line resolution of ~ 2 Å on a routine basis, researchers interested in the microstructures of crystalline solids have made an effort to interpret lattice fringe images in terms of features in the microstructure. In the earlier work, a one-to-one correspondence between the perturbing influence in the object and the observed disturbance in the lattice fringe image was assumed.
Application of Lattice Imaging Techniques to Amorphous Films
Authors: Herd S. R. , Chaudhari P.
Published: June 2020

Electron diffraction and direct transmission have been used extensively to study the local atomic arrangement in amorphous solids and in particular Ge. Nearest neighbor distances had been calculated from E.D. profiles and the results have been interpreted in terms of the microcrystalline or the random network models. Direct transmission electron microscopy appears the most direct and accurate method to resolve this issue since the spacial resolution of the better instruments are of the order of 3Å. In particular the tilted beam interference method is used regularly to show fringes corresponding to 1.5 to 3Å lattice planes in crystals as resolution tests.
Digital Image Processing in High Resolution Electron Microscopy
Authors: Frank J.
Published: June 2020

Image processing can be considered as an attempt to aid image interpretation and to improve image quality by using additional information not contained in the image, or to make optimal use of redundant information contained in the image. Since high resolution electron micrographs contain a very high amount of noise from substrate, electron statistics and photographic grain, the separation of the signal from the noise part of the image is one of the most important problems. An operation that produces an output image with a higher signal-to-noise ratio than the input image may appear as witchcraft but is in fact feasible through clever use of a-priori information such as the knowledge of object and noise statistics.
Processing of High Resolution Images by Analogue Methods
Authors: Thon F.
Published: June 2020

The information content of an electron micrograph taken under high resolution conditions in bright field phase contrast technique can be very high. In practice, however, it is impossible to extract any relevant information on the real structure of a totally unknown amorphous object from the image by visual observation. The reason is that most of the information is transferred to the image in a coded manner. This is a consequence of the complicated nature of the phase contrast transfer function (CTF) of conventional objective lenses.
In situ Electron Microscope Study of the Oxide/Metal (Cu2O/Cu) Interfacial Reaction During Annealing
Authors: Heinemann K. , Bhogeswara Rao D. , Douglass D. L.
Published: June 2020

A certain amount of oxygen is soluble in copper. The attainment of the solubility limit for oxygen near the metal surface is a necessary condition for the nucleation of oxide. The rest of the unoxidized copper may remain unsaturated with oxygen even during the oxidation and is potentially capable of dissolving additional amounts of oxygen. The disappearance of copper oxide during high-temperature annealing experiments of partially oxidized copper films as detected by T E M and TED was suggested to be due to such an oxygen dissolution process following the dissociation of copper oxide.
Electron Microscopy of Early Stages of Precipitation in Lithium Ferrite-(LiFe5O8)-Spinel
Authors: Mishra R. K.
Published: June 2020

The advent of high voltage microscopes with penetrating power higher than that of conventional microscopes and development of ion-milling technique for preparing ceramic specimens have opened up the field of microstructural characterisation of ceramic materials. The present paper describes the electron microscopy of the early stages of precipitation in ferrimagnetic lithium ferrite (LiFe5O8) spinel. These materials are of interest for applications in electronics industry. Thin slices (30ym in thickness) from a slightly lithium deficient lithium ferrite single crystal are aged at 1200°C in air for a sequence of times. Specimens for examination in HU 650 HVEM operating at 650kV are prepared from the center of these slices by mechanical polishing followed by ion-thinning.
A Study of Amine-Etched Poly (Ethylene Terephthalate) Filaments by HVEM and SEM
Authors: Tucker Paul , Murray Richard
Published: June 2020

The n-alkyl amines cleave the ester link in poly(ethylene terephthalate) (PET) and release ethylene glycol and the amine soluble N, N'dialkyl terephthalamide. Earlier work suggests that ethylamine is more selective in attack than methylamine in that regions of low structural order are attacked more rapidly than are crystalline areas. Findings similar to those described above and reported elsewhere have also been found in the present studies for treatments with a higher homologue, n-propylamine, in the neat condition.
Electron Microscopy of Porous Silicon Films
Authors: Anderson R. M. , Aboaf J. , Cameron D. P.
Published: June 2020

Thick thermal oxide films on Si are usually obtained by oxidation at high temperatures; e. g., 1 μm of thermal oxide is obtained at 1000°C after 5 hr in water vapor. Such a long oxidation step is unattractive from a Si processing viewpoint; also, defects have been observed to occur in wafers subjected to such a procedure. A porous Si film may be comparably oxidized in 3 to 4 min.

Porous Si is obtained by anodizing Si in HF solution. The growth and porosity of the porous layer depend on the type and resistivity of the Si, HF concentration, and anodizing time. Microstructural characterization shows that “pores” in Si, depending on conditions, vary from a few tens of angstroms to microns.
The Initial Epitaxy of Copper on (111) Gold Single Crystals
Authors: Macur J. E.
Published: June 2020

Two of the primary requirements needed for a successful study of epitaxy are a contamination free environment (UHV) and an extremely smooth, clean substrate surface. The deposition should be studied in situ by means of some surface sensitive technique (e.g. RHEED or LEED) and then in TEM and TED. Such a study has been conducted with Cu on (111) Au.

Extremely smooth (111) single crystals of Au were evaporated on NaCl/mica in a UHV-RHEED system whose base pressure was 7 x 10-10 torr. After a 15 minute anneal at 625°C the films were cooled to room temperature. The initial growth of Cu on (111) Au at room temperature was studied is the following manner. Fractions of a monolayer of Cu were deposited (~1A per minute) onto the Au substrate and immediately examined in RHEED.
A New High Resolution STEM for Biological Studies
Authors: Bittner J. W. , Wall J. S.
Published: June 2020

A new high resolution scanning transmission electron microscope (STEM) has been constructed in the Biology Department at Brookhaven National Laboratory. The microscope will be operated under the NIH National Research Resource Program and will be open to outside users as well as Brookhaven staff.

Since the primary goal of the facility is biological research rather than instrument development, careful attention has been paid to designing an instrument which will be easy to use, reliable, and easy to service, without sacrificing high performance. The electron gun is copied from one of the Chicago designs and operates at 100 KeV with the field emission source at room temperature in a vacuum better than 10-10 Torr.
A Simple Transmission Stage for a Scanning Electron Microscope
Authors: Lin P. S. D. , Lamvik M. K.
Published: June 2020

Unlike a CEM or high resolution STEM, where the specimen is immersed between the pole pieces of the objective lens, a scanning electron microscope has its specimen stage situated off the lens field. After scattering with the specimen, electrons follow straight paths. It is rather simple to deduce the information from the signal. A transmission stage in a SEM is therefore a useful device for studying various scattering processes and the contrast thus generated.

The transmission stage can also be used in connection with the investigation of secondary and backscattered electron emission phenomena. Previously, a back-scattered electron detector was installed in one of the scanning microscopes in the laboratory.
Energy Filter for High Resolution Low-Loss Scanning Electron Microscopy
Authors: Broers A. N. , Sokolowski J.
Published: June 2020

Images are formed in low-loss scanning electron microscopy with electrons scattered from the sample surface with little energy loss. These Electrons have not penetrated deeply into the sample and only provide information about the region immediately surrounding the incident beam. High resolution can therefore be obtained. The low energy loss electrons can be selected in two ways; by the use of an energy filter, or by arranging the detector so that only those electrons emerging almost parallel to the sample surface are collected. For optimum operation both approaches can be used simultaneously. With the high resolution low-loss method the sample is placed at the center of the pole-piece gap of a condenser-objective final lens. The action of the second half of the lens is such that for most samples only electrons emerging almost parallel to the specimen surface reach the detector. An energy filter is therefore not necessary to form a high resolution image and 20 Å point-to-point resolution (7 Å resolution using the width of the dark space criterion) has already been demonstrated without one.
Applications of Through-Focus Dark Field Image Shifts to Phase Identification
Authors: Rao Prakash
Published: June 2020

Image shifts in out-of-focus dark field images have been used in the past to determine, for example, epitaxial relationships in thin films. A recent extension of the use of dark field image shifts has been to out-of-focus images in conjunction with stereoviewing to produce an artificial stereo image effect. The technique, called through-focus dark field electron microscopy or 2-1/2D microscopy, basically involves obtaining two beam-tilted dark field images such that one is slightly over-focus and the other slightly under-focus, followed by examination of the two images through a conventional stereoviewer. The elevation differences so produced are usually unrelated to object positions in the thin foil and no specimen tilting is required.

In order to produce this artificial stereo effect for the purpose of phase separation and identification, it is first necessary to select a region of the diffraction pattern containing more than just one discrete spot, with the objective aperture.
Classical Transport Theory and the Imaging of Thick Specimens
Authors: Groves T.
Published: June 2020

It is common in transmission electron microscopy to use specimens which are of the order of a micron in thickness. For such thicknesses it becomes likely that an incident electron will scatter more than once, and one would expect some drastic effects on image formation. A theory of image formation has been derived for thick specimens in the conventional (CEM) and scanning transmission (STEM) electron microscopes. This theory is based on a solution of the Boltzmann transport equation for plural scattering, and is expected to apply to the imaging of small objects embedded in thick amorphous films.

We imagine an idealized specimen shown in Fig. 1. A point-like object is embedded in a thick film at a depth n1, measured in units of the mean free path λ for elastic scattering.
Image Analysis of Intramembrane Particles in Freeze-Fractured Biomembranes Using Computer Simulation Techniques
Authors: Benefiel D.J. , Weinstein R.S.
Published: June 2020

Intramembrane particles (IMP or MAP) are components of most biomembranes. They are visualized by freeze-fracture electron microscopy, and they probably represent replicas of integral membrane proteins. The presence of MAP in biomembranes has been extensively investigated but their detailed ultrastructure has been largely ignored. In this study, we have attempted to lay groundwork for a systematic evaluation of MAP ultrastructure. Using mathematical modeling methods, we have simulated the electron optical appearances of idealized globular proteins as they might be expected to appear in replicas under defined conditions. By comparing these images with the apearances of MAPs in replicas, we have attempted to evaluate dimensional and shape distortions that may be introduced by the freeze-fracture technique and further to deduce the actual shapes of integral membrane proteins from their freezefracture images.
Electron Energy Loss Microanalysis of an Internally Oxidised Ni-Al Alloy
Authors: Ditchfield R W , Fourdeux A , Whelan M J
Published: June 2020

A good strength, high temperature Ni-Al alloy had been produced by thermomechanically cycling sintered aluminium and nickel powders. The microstructure of the alloy consisted of a solid solution in which there was a fine dispersion of inert ceramic particles. A typical micrograph is shown in Fig 1 in which three distinct types of particle A, B and C are indicated. To explain the mechanical properties of the alloy it was necessary to determine the composition and structure of the particles.

As the particles were 300Å to 1200Å in size the only satisfactory method to use was combined electron microscopy and energy analysis. Thinned foils containing unobscured particles were used so that, by placing slit of the Mollenstedt analyser across it, the energy loss spectrum of each particle was measured directly.
Mass Determination by Direct Measurement of Electron Scattering
Authors: Lamvik M. K. , Crewe A. V.
Published: June 2020

If a molecule or atom of material has molecular weight A, the number density of such units is given by n=Nρ/A, where N is Avogadro's number and ρ is the mass density of the material. The amount of scattering from each unit can be written by assigning an imaginary cross-sectional area σ to each unit. If the current I0is incident on a thin slice of material of thickness z and the current I remains unscattered, then the scattering cross-section σ is defined by I=IOnσz. For a specimen that is not thin, the definition must be applied to each imaginary thin slice and the result I/I0=exp(-nσz) is obtained by integrating over the whole thickness. It is useful to separate the variable mass-thickness w=ρz from the other factors to yield I/I0=exp(-sw), where s=Nσ/A is the scattering cross-section per unit mass.
Energy Dispersive X-Ray Analysis of Picoliter Samples of Physiological Fluids
Authors: Quinton Paul M.
Published: June 2020

Investigations of biological parameters at increasingly refined levels have sustained interest in methods for analyzing diminishingly small quantities of biological fluids. This report presents a rapid, straight forward procedure for elemental analysis of volumes on the order of 50 picoliters or less using the scanning electron microscope coupled with energy dispersive X-ray analysis. This technique has advantages over previously reported methods in that the preparation is faster, no freeze drying is necessary, and all elements heavier than flouride can be analized simultaneously.
Surfactant Bodies: The New Look o£ the Lamellar Inclusions from Type II Alveolar Pneumocytes
Authors: Wagner R. M. , Miyai K.
Published: June 2020

Lamellar bodies, inclusions unique to type II alveolar cells, have an essential role in the metabolism of the surface-active lipoproteins of the mammalian lung. Most recent investigations have shown that the type II alveolar cell also functions as a progenitor of alveolar epithelial regeneration in certain types of alveolar injury, thus emphasizing the need for complete characterization of this cell and its lamellar inclusions. This paper presents a new appearance for the lamellar inclusion in situ as well as in isolated fraction and suggests a correlation between the improved appearance and the biochemical composition of the inclusion.

The lungs from adult male rats were removed and 1 mm3 blocks were cut from the peripheral lung regions for the in situ studies. This tissue was fixed in 1% OSO4 in 0.15 M isotonic buffered saline at 4°C for 2 hours then dehydrated with a graded series of acetone at 4°C and embedded in Luft's Epon.
Middle Cerebral Artery Response Following Occlusion with a Surgical Clamp
Authors: Dodson Ronald F. , Tagashira Yukio , Chu Lena W.F. , Scates Ronald W.
Published: June 2020

One of the most consistently reproducible models for studying experimentally induced cerebral infarction in animals has been through surgical occlusion (clamping) of the middle cerebral artery (MCA). The resultant morphological, hemodynamic, and metabolic changes in brain tissue mimic those which occur in man following stroke. Although numerous reports exist which have incorporated this model in their study of ischemic effects on the brain, a void of information exists as to the morphological response of the vessel and its associated nerve bundles following the application of the clip.

Adult squirrel monkeys used in this investigation were subjected to transorbital occlusion at the M-l segment of the right middle cerebral artery for respective periods of either 1/2, 1,2,3 or 4 hrs. At the end of the selected time period, the clip was removed and the animals were subjected to whole body perfusion with 500 ml of 3% glutaraldehyde in 0.1 M phosphate buffer.
Fine Structural Analysis of Muscle Degeneration Caused by Amyloid Infiltration
Authors: Rodgers O. G. , Shirahama T. , Cohen A.S.
Published: June 2020

Amyloidosis, especially the primary type, often causes myopathies including heart failure. These myopathies are believed to be secondary to the infiltration of amyloid around and into the muscle cells. However no detailed ultrastructural study has been available on this subject in either skeletal or cardiac muscle.

The intrinsic muscle ultrastructure of tongue obtained at hemiglossectomy from two patients with systemic primary amyloidosis with macroglossia were studied. The results were analysed to assess the process of muscle atrophy caused by infiltration of the amyloid fibrils.

The atrophic process can be classified into five phases. 1) In the area free of and remote from the amyloid deposition muscle ultrastructure was normal (Fig. 1). 2) While larger amounts of amyloid fibrils were deposited around the muscle cells, amyloid fibrils were also found in the muscle cells forming relatively large islands or in small amounts among the myofibrils.