bluuebunny/crossref_metadata_2025 huggingface dataset:
A HVEM and SEM Study of Elongation Rate Effects on Fracture Mechanisms in Ag Crystals
Authors: Lyles R.L. , Wilsdorf H.G.F.
Published: June 2020

The application of high voltage electron microscopy, combined with the ability to record dynamic phenomena, represents a most effective means of studying the microstructural mechanisms of fracture by direct observation. Using techniques described previously, the University of Virginia's 500 kV electron microscope has been utilized for in situ investigations of phenomena occurring during crack propagation. Chemically grown, (111) <110> single crystal silver ribbons (.5-2μ thick,.5-1 mm wide, and 3-5 mm long) were strained to fracture at elongation rates of 102Å/sec, 103Å/sec, and 104−105Å/sec. in a precision straining stage.

The orientation of the tensile specimens was such that the (111) plane was normal to the electron beam while the tensile axis was aligned with the [011] direction. Accordingly, when the crystals were strained, a 30° lattice rotation around the [111] pole resulted in the initial <110> tensile axis reorienting to a <112> direction. The failure of the specimens occurred under this new orientation.
Depth Distribution of Defect Clusters in Electron Irradiated Aluminum Films
Authors: Rao Prakash
Published: June 2020

The possibility of creating displacement damage by electron irradiation of materials in the high voltage microscope has led to several recent studies of the nature and growth of point defect clusters created by such irradiation (e.g. Ref. 1). A study of the depth distribution of such defect clusters is of interest since the film surfaces, surface contaminants, dislocations and grain boundaries should control the size and may even influence the nature of these clusters. In such cases, stereoscopic viewing has the advantage that defect densities can be measured locally and as a function of depth in the specimen rather than as an average over the film thickness.

Polycrystalline aluminum films 6250Å thick were evaporated onto cleaved rock salt substrates held at 350°C under a vacuum of 10−8 Torr. The films were irradiated at room temperature in the Berkeley 650kV electron microscope to a total dose of 6.6×l022 electrons/cm2 corresponding to 17.4 displacements/atom.
The Interaction of Fast Electrons with Aromatic Amino Acids
Authors: Lin Paul Shau-Da
Published: June 2020

As part of a program in investigating the interaction of electrons with biological molecules in a field emission scanning microscope, we have studied the energy loss spectra of aromatic amino acids: Tryptophan, Tyrosine and Phenylalanine.

The instrument used is the simple multipurpose scanning microscope previously constructed. The high resolution magnetic spectrometer installed in this microscope enables a resolution of ∽.2 ev as limited by the energy spread in field emission only.

The energy loss spectra of Tyrosine and Tryptophan are shown in Figs. 1 and 2. In general, they consist of several peaks below ∼l0 ev, a broad one around 25 ev, and some shoulders on the broad peak. The structure below ∽10 ev bears close correlation with UV, far UV or synchrotron radiation spectra, and can be deduced from each other by Kramers-Kronig transformation. For biological specimens, this has more recently been demonstrated for Nuclei-Acid Bases.
Quantitative Studies of Individual Atoms and Clusters on Solids
Authors: Ehrlich Gert , Stolt Kaj
Published: June 2020

The invention of the field ion microscope by Müller in the 1950's opened up for scientific examination a whole range of interesting phenomena. For the first time it was possible to see single atoms on a solid, a capability illustrated in Fig. 1. Especially in studies of solid surfaces this ability is crucial. The atomic arrangement at crystal interfaces, modelled in Fig. 2, is strongly dependent upon the orientation and is likely to have a profound effect upon atomic behavior. Exploration of atomic properties in relation to interfacial structure is therefore necessary for an understanding of phenomena such as crystal and thin film growth, evaporation, surface transport and sintering. The field ion microscope, with its ability to depict individual adatoms, has proved itself a powerful tool for such studies of atomic behavior.
Radiation Damage Study of Crotoxin Complex Crystal at 4K and 300K
Authors: Chiu W. , Knapek E. , Jeng T.W. , Dietrich I.
Published: June 2020

Radiation damage is the most fundamental problem in the structural study of biological and organic materials by electron microscopy. Low dose technique has been rather successful to record images of beam sensitive biological crystals out to 5-7Å resolution at room temperature. However, if the specimen is kept at low temperature, the effect of radiation damage would be reduced and it will enhance the feasibility of recording images of biological crystals beyond this resolution limit. We have investigated the radiation damage kinetics of crotoxin complex thin crystal embedded in glucose at both 300K and 4K.

The room temperature experiment was conducted with a JEM100CX electron microscope at 100kV, and the low temperature experiment was conducted with the superconducting lens microscope at 220kV, built in Siemens. The experimental method was to record a successive electron diffraction pattern from the same crystal at increasing accumulated doses. These patterns were then digitized with a Perkin Elmer microdensitometer and the intensities of each reflection were integrated with the background being subtracted.
Apparent Temperature Factor Due to Dynamical Scattering in Electron Diffraction of Protein Crystals
Authors: Ho Ming-Hsiu , Jap Bing K. , Glaeser Robert M.
Published: June 2020

The failure of the kinematic scattering approximation, and also of the “weak phase object” approximation, may represent one of the most serious problems in the interpretation of high resolution electron diffraction data and electron microscope images. The existence and behavior of dynamical diffraction effects are well characterized in materials science applications, but the possible influence of dynamical effects is still not completely understood in applications involving unstained biological materials, which are characterized by low atomic number and large unit cells. We have previously reported numerical calculations in which we have explored the conditions under which the kinematic approximation would be valid, to an acceptable level of accuracy, for complex biological structures. The known structure of a protein, cytochrome b5, was used as a test object, and the Cowley-Moodie multislice method was used to calculate the “exact” dynamical diffracted waves. For 100 keV electrons it has been found that the kinematic approximation is acceptable up to a specimen thickness of about 150 Å, as judged by the crystallographic “R-value”, by the appearance of the difference Patterson function (for heavy atom derivatives), and by the number of wrong phases that are derived from the dynamical diffraction intensities.
Evaluation of High-Resolution Features in Images of Negatively Stained Tobacco Mosaic Virus
Authors: Chang Chung-Fu , Williams Robley C. , Grano David , Glaeser Robert M.
Published: June 2020

Using the “minimal exposure” technique of Williams and Fisher, it is routinely possible to obtain electron micrographs of negatively stained Tobacco Mosaic Virus (TMV), whose optical diffraction patterns show strong, nearmeridional intensity on the 3rd layer line, corresponding to the major structural features (“striations”) with an axial repeat distance of ∼23Å. Under appropriate negative-staining conditions it is also possible to obtain images whose optical diffraction patterns have distinct near-meridional intensity on the 6th layer line, corresponding to structural features at a resolution somewhat better than 12Å. We report here our evaluation and analysis of one such image. In this work we compare the results obtained by photographic superposition (translational averaging) to the results that are obtained through image processing with the computer. The photographic processing method was found to produce a surprising amount of spurious intensity on the principal layer lines, both at low resolution and at high resolution.
Microstructure of Vanadium-Oxygen Alloys
Authors: Lawless K. , Kenik E. A. , Bentley J.
Published: June 2020

The present study is a continuation of our investigation on in situ oxidation of vanadium and vanadium-titanium alloys. Vanadium is a reactive metal and forms a large number of oxides during high-temperature exposure to oxygen. The microstructure of the oxides formed during the first stages of oxidation and the transformations between oxide phases are under investigation.

Single crystal specimens were oxidized in situ using the ORNL Hitachi HU-1000 high voltage electron microscope (HVEM). Both total pressure and residual gas composition were monitored during the experiments. In addition to in situ HVEM observations, high resolution lattice imaging and convergent beam electron diffraction were performed in JEOL 120CX and Philips EM-400T/FEG analytical electron microscopes (AEM).

During exposure to oxygen, the transformation to oxide occurs first in the thinnest regions of the foil where the concentration of absorbed oxygen is highest. As oxidation proceeds, the transformation zone moves into thicker regions of the foil.
High Resolution Electron Microscopy of Incommensurate Superlattices
Authors: Iijima Sumio , Bando Yoshio
Published: June 2020

Diffraction patterns of crystals having long period superlattices are described by their matrix lattice reflections, M = ha* + kb* + lc*, and a set of satellite reflections S appearing around each matrix reflection, which are characterized by S = m1a* + m2b* + m3c*. For usual superstructures the m's become rational numbers but for certain superstructures they are irrational. The latter are called the incommensurate superstructures. Crystal structure analysis by the conventional diffraction methods is based on perfectly periodic structures and generally cannot be applied to the crystals having the irrational superstructure periodicities. This paper deals with the study of such crystals using the high resolution lattice imaging method and the types of information obtained are discussed. It was intended that the study not only supplement the information on statistically averaged structures obtained from diffraction data but also provide further understanding of the incommensurate structures.
Atomic Imaging of the Amorphous State
Authors: Gibson J.M.
Published: June 2020

When an electron microscopist takes a high resolution image of an amorphous object, perhaps he has something in common with a pianist who tackles a complex atonal sonata. Both efforts could represent a pinnacle of achievement for the performer and his instrument but the pianist's audience may not immediately recognize the difference if a monkey were to walk over the keys. To stretch the analogy, a perfect lattice image could be equated to a faultless rendition of a Haydn Sonata: aesthetically satisfying but predictable. One conclusion from a decade's work on the subject (see a recent review by Howie) is that high resolution images from amorphous samples are not easily interpreted directly. One can learn more about the atomic arrangement in amorphous materials from such images if one treats them rather as quantitative information about the local scattering properties than pictures.
Point Defect and Interface Imaging at the Atomic Resolution Level
Authors: Krakow W. , Tan T.Y. , Foell H. , Cherns D. , Smith D.A.
Published: June 2020

The ultimate goal of high resolution electron microscopy is to obtain a structure image which is representative of the atomic arrangement of a thin film. The problem in achieving this goal is two-fold involving: (1) the diffraction mechanisms of the specimen of interest (structure, orientation, inelastic scattering, thickness) and (2) the modification of the diffracted waves by the microscope electron optics (aberrations, beam tilt and divergence). These two difficulties are often intermixed with one being a direct consequence of the other. Several authors have considered some of these effects for perfect crystalline structures which include those of tungsten bronze. Si and Ge. Axial illumination has been the standard imaging mode for these investigations since only a radial contrast transfer function need be considered. The analysis of data from micrographs has been simplified by considering a discrete or small number of Bragg beams at specific reciprocal space positions.

The analysis of images of defects requires a more detailed knowledge of the reciprocal space scattering distribution of a specimen which includes the diffuse scattering. Hence, a full two dimensional map of the phase shifts introduced by the microscope optics is needed. The two main classes of defects which will be considered for crystalline materials are: (1) point defect rows and (2) intercryslalline interfaces. The main reason for classifying an interfacial region separately that scattered waves from different crystal phases or crystal orientations on each side of the boundary can extend into the other and complicate image interpretation.
High Resolution Electron Microscopy of Semiconductor Defects
Authors: Spence J.C.H.
Published: June 2020

Any attempt to study the relationship between the electronic and atomic struc ture of isolated defects in semiconductors by high resolution electron microscopy must deal with the following difficulties: (i) The limited point reso lution of modern TEM instruments, which has fallen by about 1Å from 3.8Å to 2.8Å (with tilt) over the last decade. This is still not sufficient to resolve the individual atomic columns in any semiconductor. (ii) The fundamental difficulties in obtaining both high spatial resolution structural information and high energy resolution spectroscopic data from the same, isolated, defect. (iii) The considerable difficulties in extracting chemical, or atomic number information from electron scattering and imaging experiments with high spatial resolution. Among other problems, the separation of composition variation effects from those of thickness is an important problem. Some of our recent approaches to these problems are outlined below.
Digital Processing of STEM Images
Authors: Crewe A. V. , Ohtsuki M.
Published: June 2020

We have assembled an image processing system for use with our high resolution STEM for the particular purpose of working with low dose images of biological specimens. The system is quite flexible, however, and can be used for a wide variety of images.

The original images are stored on magnetic tape at the microscope using the digitized signals from the detectors. For low dose imaging, these are “first scan” exposures using an automatic montage system. One Nova minicomputer and one tape drive are dedicated to this task.

The principal component of the image analysis system is a Lexidata 3400 frame store memory. This memory is arranged in a 640 x 512 x 16 bit configuration. Images are displayed simultaneously on two high resolution monitors, one color and one black and white. Interaction with the memory is obtained using a Nova 4 (32K) computer and a trackball and switch unit provided by Lexidata.

The language used is BASIC and uses a variety of assembly language Calls, some provided by Lexidata, but the majority written by students (D. Kopf and N. Townes).
Computer Aid for the Scanning Transmission Electron Microscope
Authors: Batson P. E.
Published: June 2020

Analytical Electron Microscopy has been made possible through large technological advances in electron microscopes and in their associated data taking equipment. Among these advances are successful field emission electron sources, allowing reasonable current densities in small probe sizes; and computer based data acquisition systems for characteristic x-ray (EDX) and electron energy loss (EELS) detection, allowing simple viewing and easy processing for elemental analysis. These advances tend to bring new and complex problems of their own, however. For instance, a field emission source routinely produces a 3.5 to 5 Å sized probe in the VG Microscopes, Ltd. HB5 STEM. But a specimen drift of about 20 Å per minute, coupled with a 60 Hertz beam deflection of about 10 Å in an ambient magnetic field of about 4 mG, makes it difficult to confidently analyze areas smaller than about 50 Å in diameter during a ten minute experiment. Problems with presently available data acquisition systems arise from the need to synchronize the data taking device with the microscope.
Amorphous Phase Separation in Vapor-Quenched Cu-Zr
Authors: Marshall A. F. , Walmsley R. G.
Published: June 2020

Noncrystalline Cu-Zr alloys can be formed by liquid or vapor quench techniques over a wide range of compositions. These noncrystalline structures are typically homogeneous. We have recently observed a microstructure apparently composed of two amorphous phases in noncrystalline sputter-deposited Cu-Zr at a composition of 40 at% Zr. The occurrence of two amorphous phases in this material was also indicated by x-ray diffraction, differential scanning calorimetry, and electrochemical measurements. The purpose of this paper is to confirm and characterize the two-phase microstructure using the analytical electron microscope.

The CuZr films were formed by magnetron sputter deposition in a phase spread mode, i.e., separated Cu and Zr sputtering sources producing a range of compositions on the static substrate. TEM specimens at the composition 40 at% Zr were prepared by ion milling. It was necessary to mill at very low beam currents to avoid excessive heating of the specimen and consequent changes in the microstructure.
Identification of a Grain Boundary Nucleated Phase in 300m Steel
Authors: Padmanabhan R. , Wood W. E.
Published: June 2020

One reason proposed for the improvement of plane strain fracture toughness (at similar yield strength levels) of UHSLA steels, austenitized at 1473°K, rather than the conventional 1143°K, is the elimination of non-martensitic phases, at prior austenite grain boundaries. However, contrary to expectations, optical microscopy results from early investigations suggested the existence of bainite at prior austenite grain boundaries in both 4340 and 300M steels when oil quenched from 1473°K and tempered at 180°C or 280°C (but not when quenched from 1143°K). The purpose of the present investigation was to identify through TEM the nature of grain boundary nucleated phase in 300M steel and to observe whether it is absent in the 1143°K heat treatment as reported earlier. A blocky grain boundary phase, resembling lower bainite was observed readily by SEM analysis of etched metallography samples (Fig. 1 a and b). This phase was studied further through TEM and the results are presented in Figs. 2 and 3 for the 1143°K and the 1473°K austenitized specimens respectively.
A TEM Study of the Evolution of Strain-Induced Martensite
Authors: Staudmanner K. P. , Murr L. E. , Hecker S. S.
Published: June 2020

We have demonstrated previously the effects of strain, strain state, strain rate, and temperature on the morphology of strain-induced martensite in type 304 stainless steel. In all cases α' martensite nucleated at shear band intersections as suggested by Olson and Cohen, but the final morphologies were different. As the amount of martensite increased (with increasing strain, biaxial tension, low strain rates, and low temperatures), α' appeared more blocky and less lath-like. We have demonstrated that α' embryos grow by coalescence of new embryos, rather than actual growth.

In the present study, we concentrated on the early stages of transformation to determine if α' embryos are identical for test conditions including uniaxial tension, biaxial tension, and shock loading, at room and cryogenic temperatures (as detailed in the caption of Fig. 1). Strain levels were controlled to produce only small amounts of α'. Sheet specimens, 0.18 mm thick, were used for all experiments, thinned to electron transparency, and examined in a JEOL 200B microscope operated at 200 kV.
Microstructure of Deformed AISI 4340 Steel
Authors: Sastry C. N.
Published: June 2020

The microstructure of low alloy steels has been studied by several investigators. They have shown that when low alloy steel is quenched from 1200°C, the martensite formed exhibits packets of dislocated laths containing auto tempered carbide within the laths and thin films of retained austenite at the lath boundaries. The present study is aimed to investigate the effects of deformation on microstructure of AISI 4340 steel. Tensile plate specimens were austenitized at 1200°C for 1 hr in argon atmosphere, oil quenched and tempered at 180°C for 1 hr. Following the heat treatment, these specimens were uniaxially pulled in tension and thin foils for TEM were taken from the surface of broken tensile specimen. Foils were also prepared from undeformed region. These foils were observed at 100 kv in Hitachi HU 11B microscope.
Dual Ferrite-Martensite Treatments of an ASTM A588 HSLA Steel
Authors: Chen L.J. , Yang J.R.
Published: June 2020

During the past several years duplex ferrite-martensite (DFM) steels have received increasing attention for improved strength and weight applications, since they contain characteristic microstructural features that combine high strength with good formability. ASTM A588 is one of the most widely used classes of high strength low alloy (HSLA) steels. It possesses the atmospheric corrosion resistance property as well as relatively high yield strength (∼35 kg/mm2) in the normalized condition. DFM treatments has been applied to the A588 steel.

The treatments consisted of initial austenitization and quenching to form 100% martensite, followed by annealing in the (α+γ) region at different temperatures and subsequent quenching. The DFM structure samples were also tempered at 200°-600°C for one hour. Phase diagram of a model steel and the schematic of treatments are shown in Figs. 1(a) and 1(b), respectively. Hardness, ultimate tensile strength, yield strength, elongation and Charpy impact values were measured for thermally treated samples.
The Microstructure of “Triple Beam” Ion Irradiated Fe-10% Cr
Authors: Horton L. L. , Bentley J. , Jesser W. A.
Published: June 2020

Defect structures which result from fusion environment irradiation of Fe-10%Cr have been studied by transmission electron microscopy (TEM) at 120 kV in a JEM 120C equipped with a special objective lens pole piece for the observation of magnetic materials (AMG). High-purity Fe and Fe-10% Cr disk specimens (3 mm diameter) were bombarded in the ORNL dual Van de Graaff accelerator system at 725, 775, 800, 850, 900, and 950 K. A “triple beam” of He+, D2+, and 4 MeV Fe++ ions was used to achieve 10 dpa with 100 appm He and 410 appm D. In preparing specimens for TEM, the controlled removal or “sectioning” of the damaged region to a predetermined depth was followed by “back-thinning.” A sectioning depth of 0.9 μm was selected, based on the damage-depth profile for a cross section of an electroplated iron specimen (Fig. 1). The maximum cavity volume fraction occurred at ∼1 μm and the maximum dislocation density at ∼1.5 μm. These results do not correspond to the deposited energy and deposited iron depth profiles calculated by the E-DEP-1 computer code.
High Resolution Dark Field of Poly(p-Phenylene Benzobisthiazole)
Authors: Minter J.R.
Published: June 2020

The resolution attainable in polymer samples is limited by radiation damage causing crosslinking or chain scission with subsequent loss of mass. Molecules containing aromatic groups have been found to have improved resistance to beam damage, presumably due to resonance stabilization of radicals generated by the electron beam. Poly(p-phenylene benzobisthiazole) (PBT), a wholly aromatic, heterocyclic polymer used in high modulus, high strength fibers and films has been studied by tilted beam dark field

Samples thin enough for TEM were prepared from bulk films by extraction replication with collodion and examined in a JEOL 100 CX operated at 100 KV using Kodak 4463 film. Figure 1 shows the decay of the 2nd, 3rd and 4th equatorial reflections as a function of electron dose. The intensity was assumed to be proportional to the current on the isolated observation screen when the microscope was operated in the diffraction mode and the appropriate reflections selected with a 2.8 mrad objective aperature (see Figure 1).
Improved Virus Particle Counting by Direct Sedimentation onto EM Grids
Authors: Miller Mahlon F. , Rdzok Edward J.
Published: June 2020

Investigators who have attempted to sediment virus particles directly onto EM grids have reported problems with: a) tearing of plastic support films covering grid openings, b) uneven distribution of virus due to depression of support films in grid openings during ultracentrifugation, c) failure of sedimented and stained particles to adhere to support films, and d) lack of uniformity of negative stain. The design of a new particle counting rotor and its use in preparing particulate specimens for counting by either the pseudoreplication or thin section methods was previously reported. In the present communication, a simple and reliable procedure is described in which this rotor is utilized to sediment virus particles directly onto grids for counting. The rotor (Fig. 1) operates in the Beckman AirfugeTM tabletop ultracentrifuge.

In preparation for counting, 500 mesh copper grids are sandwiched between parlodion support films and 5 mm2 Millipore filter squares (Fig. 2) which conveniently holds grids in a vertical position at the base of sector cells in the rotor core (Fig. 1).
Specific Labeling of Protein Domains with Antibody Fragments
Authors: Aebi U. , Buhle L.E. , Fowler W.E.
Published: June 2020

Many important supramolecular structures such as filaments, microtubules, virus capsids and certain membrane proteins and bacterial cell walls exist as ordered polymers or two-dimensional crystalline arrays in vivo. In several instances it has been possible to induce soluble proteins to form ordered polymers or two-dimensional crystalline arrays in vitro. In both cases a combination of electron microscopy of negatively stained specimens with analog or digital image processing techniques has proven extremely useful for elucidating the molecular and supramolecular organization of the constituent proteins. However from the reconstructed stain exclusion patterns it is often difficult to identify distinct stain excluding regions with specific protein subunits. To this end it has been demonstrated that in some cases this ambiguity can be resolved by a combination of stoichiometric labeling of the ordered structures with subunit-specific antibody fragments (e.g. Fab) and image processing of the electron micrographs recorded from labeled and unlabeled structures.
Mapping the Ribosomal Exit Site of the Nascent Polypeptide Chain by Immune Electron Microscopy
Authors: Bernabeu Carmelo , Lake James A.
Published: June 2020

Immune electron microscopy is providing information on the three dimensional locations of many functional sites on the ribosome. In particular, localization of the exit site of the newly synthesized protein chain is expected to provide information on the mechanisms of protein synthesis and on the nature of the ribosome-membrane association. Theoretically the nascent chains of the largest proteins could be visible as they leave the ribosome, but in practice they have not been observed. In order to map their exit site we have made antibodies against one particular enzyme and then applied immune electron microscopy to a polysome fraction enriched for that special protein.

In a mutant of Escherichia coli constitutive for the enzyme beta-galac- tosidase, this enzyme accounts for approximately 25% of the total protein (1). Because of the high molecular weight of beta-galactosidase, a fraction of larger polysomes, further enriched in this emzyme, was obtained by differential centrifugation. When IgG antibodies against this enzyme are reacted with polysomes, two types of profiles are observed.
Ribosome Structure Investigated by Digital Accumulation and Processing of Ribosome Tetramer Images
Authors: Lamvik M. , Kunath W. , Sack-Kongehl H.
Published: June 2020

Electron microscopic observation of ribosomes, especially combined with 3-D reconstruction methods, may reveal structural relationships among components of the ribosome. In such studies it is necessary to average over a large number of specimen particles, to enhance the predominant structure while suppressing local irregularities of specimen preservation and staining, and to reduce the statistical insufficiencies of individual low-dose electron micrographs. One very successful method makes use of an average over the particles in a two-dimensional crystalline layer, but if the particles are not well organized, the resolution is reduced. Organization of crystalline arrays can be enhanced by computer methods, but if computational alignment is used it seems most profitable to avoid the restriction to crystalline spec- iment completely and work with isolated particles. A fixed orientation is still helpful; so in studying ribosomes, which lack their own symmetry, we have chosen to observe ribosome tetramers. The tetramers, units of the chick embryo ribosome crystal, present a fixed view in the electron micrograph.
The Red Neuronal Pigment in the Nervous System of the Mussel, Mytilus Edulis: Localization and Its Effect on Lateral Ciliary Activity with Spectral and Analytical Changes
Authors: Paparo Anthony A. , Murphy Judith A.
Published: June 2020

The purpose of this study was to localize the red neuronal pigment in Mytilus edulis and examine its role in the control of lateral ciliary activity in the gill. The visceral ganglia (Vg) in the central nervous system show an over al red pigmentation. Most red pigments examined in squash preps and cryostat sec tions were localized in the neuronal cell bodies and proximal axon regions. Unstained cryostat sections showed highly localized patches of this pigment scattered throughout the cells in the form of dense granular masses about 5-7 um in diameter, with the individual granules ranging from 0.6-1.3 um in diame ter. Tissue stained with Gomori's method for Fe showed bright blue granular masses of about the same size and structure as previously seen in unstained cryostat sections.Thick section microanalysis (Fig.l) confirmed both the localization and presence of Fe in the nerve cell. These nerve cells of the Vg share with other pigmented photosensitive cells the common cytostructural feature of localization of absorbing molecules in intracellular organelles where they are tightly ordered in fine substructures.
Electron Microscopy of Fibroblasts from Myotonic Muscular Dystrophy Patients
Authors: Miller S. E. , Hartwig G. B. , Nielsen R. A. , Frost A. P. , Roses A. D.
Published: June 2020

Many genetic diseases can be demonstrated in skin cells cultured in vitro from patients with inborn errors of metabolism. Since myotonic muscular dystrophy (MMD) affects many organs other than muscle, it seems likely that this defect also might be expressed in fibroblasts. Detection of an alteration in cultured skin fibroblasts from patients would provide a valuable tool in the study of the disease as it would present a readily accessible and controllable system for examination. Furthermore, fibroblast expression would allow diagnosis of fetal and presumptomatic cases. An unusual staining pattern of MMD cultured skin fibroblasts as seen by light microscopy, namely, an increase in alcianophilia and metachromasia, has been reported; both these techniques suggest an altered glycosaminoglycan metabolism An altered growth pattern has also been described. One reference on cultured skin fibroblasts from a different dystrophy (Duchenne Muscular Dystrophy) reports increased cytoplasmic inclusions seen by electron microscopy. Also, ultrastructural alterations have been reported in muscle and thalamus biopsies from MMD patients, but no electron microscopical data is available on MMD cultured skin fibroblasts.
Virus Particles Infected the Erythrocytes of Cultured Eel in Taiwan
Authors: Liu Kuo-chun
Published: June 2020

The erythrocytes infected by viral particles and the pathological conditions by the presence of those viral particles were reported in cod, herring and few other species of fish in the western waters. This report will present the evidence that the erythrocytes of some of the cultured eel in Taiwan were infected by virus particles.

In the summer of 1980, in one of the field trips to the fish farms in Lotung county, northeastern of Taiwan, the author was informed that dead eels from unknown cause were picked up from eel ponds every morning. Samples were collected the following morning. There was no observable external symptom.

The internal organs showed a red coloration (Fig. 1,2). Tissues from the livers and gills were processed for electron microscopic observation. Virus particles were found in some of the erythrocytes in both organs (Fig.3).

The viral particles aggregated together as an inclusion body in the cytoplasm only. No intranuclear viral particle was found. In a single viral aggregate 1 to 40 particles were observed. A electron lucent ring separated the viral aggregate from the hemoglobin cytoplasm.
A Heavy Metal Tracer Method for Demonstrating Fluid and Ion-Accessible Channels in Epithelia
Authors: Simson J. A. V. , Wilmeth S.
Published: June 2020

The use of enzymes such as horseradish peroxidase or of metal-containing macromolecules such as ferritin and iron dextran have been extremely valuable in tracer studies designed to determine the fate of exogenous macromolecules during endocytosis and in exocytosis/endocytosis coupling during secretion. An important unanswered question in the cell biology of secretion is: How do small molecules and inorganic ions gain access to the lumina of secretory epithelium during secretion? Macro molecular tracers cannot be used to answer this question since they are larger than the pore sizes involved, and most heavy-metal-containing small ionic tracers (such as lanthanum and ruthenium red) have been used only in the presence of fixatives to determine the existence of channels that remain patent in fixed cells and tissues. These tracers have only rarely been used to examine functioning fluid-permeable channels because of their toxicity to living cells (see Hayat, 1975). It is clear, however, that the equilibration of very small ions and molecules across a permeable barrier (e.g., fenestrated capillaries) occurs very rapidly, in a matter of perhaps 2-4 seconds.
Synthesis of Enamel Matrix Glycoproteins as Demonstrated by Radioautography
Authors: Weinstock A.
Published: June 2020

Enamel matrix, an organic material produced by ameloblasts, contains glycoproteins which are 88-95% carbohydrate (Glimcher & Levine, 1966). Although these glycoproteins have not been well characterized, their carbohydrate moieties are known to consist of monosaccharide units which include glucose, galactose, mannose and fucose. It was decided to investigate the formation of these glycoproteins in ameloblasts using radioautography in order to locate the site of glycoprotein synthesis, and to follow the route of migration of the labeled secretory material out of the cell.

Rats weighing 30 gm were injected intravenously or intraperitoneally with 3H-galactose or 3H-glucose. In another experiment, rats were injected with puromycin prior to 3H-galactose administration. At various time intervals ranging from 5 min. to 1 hour after injection, the animals were anaesthetized with ether, and perfused via the left ventricle with phosphate-buffered glutaraldehyde (2.5%). After decalcification, sections of teeth were processed for light and electron microscope radioautography.
Wilson's Disease: Liver Cirrhosis and Virus-like Particles
Authors: Hairstone M. A. , Modjtabai A. , Azerbeygui J. , Shamsa T.
Published: June 2020

Hepatolenticular degeneration (Wilson's disease) manifests itself in many ways the most obvious of which is a disorder of copper metabolism. Normally copper beyond a certain threshhold is transferred to ceruplasmin which may circulate in the plasma. In patients with Wilson's disease this transfer apparently does not take place. There follows an accumulation of the metal in body tissues most notably the lenticular nucleus and the liver.

Needle biopsies taken of the liver of an 11 year old male with Wilson's disease was prepared for light and electron microscopy by conventional methods. Thin sections were examined with Elmiskop 1A.

Histologically the liver alteration was that of cirrhosis in which the cells showed fatty and glycogenic degeneration, cytoplasmic coagulation, fibrosis, and pigment deposition. Electron microscopy confirmed and extended light microscopy.
Electron Microscopy of the Nucleic Acid of Mouse Mammary Tumor Virus
Authors: Sarkar N. H. , Moore Dan H.
Published: June 2020

Mouse mammary tumor virus (MTV) is believed to contain about 0.8% single stranded ribonucleic acid (RNA). This value of RNA content was estimated on a dry weight basis. The subject of this report is an attempt to visualize the RNA molecules of MTV particles.

MTV particles were isolated from RIII mouse (tumor incidence approximately 80%) milk according to the method described by Lyons and Moore. Purified virions from 5 ml of milk were finally suspended in 0.2 ml of PBS, pH 7.4 and was mixed with an equal volume of pronase (5 mg/ml). This mixture was incubated at 37°C for an hour. RNA was extracted three times using freshly prepared cold phenol. It was then treated three times with cold ethyl ether to remove any trace of phenol. The RNA thus extracted was divided into two parts. One part was diluted four fold with 8M urea to avoid aggregation of the molecules. The other part was left untreated. Both samples were then mixed with an equal volume of 1M ammonium acetate, adjusted to pH 8.0 with NH3 containing chymotrypsin at a concentration of 0.01%.
Selective Staining of Nucleic Acids with Indium
Authors: Aldridge W. G. , Coleman J. R.
Published: June 2020

Heavy metal compounds are used to increase contrast in electron microscope specimens by virtue of strong electron scattering properties. Chemical properties of heavy metal atoms cause them to discriminate amongst available ligands, a property useful for biological specimens. Decreasing available specimen ligand types produces a narrow reaction spectrum. Taking advantage of both these controlling factors, one can produce a very narrow reaction spectrum and thus high selectivity. This approach was utilized in the development of methods for the use of indium as an “electron stain” for nucleic acids. Here selectivity is greatly enhanced by reduction and acylation reactions which precede exposure to indium trichloride dissolved in anhydrous acetone. Nucleic acid phosphate is the predominant binding site but some non-nucleic acid ligands still bind indium. To further increase selectivity and provide greater contrast (thus lower detection limits), more efficient blocking reactions of broader chemical reactivity plus techniques to increase the amount of heavy metal bound to nucleic acid were sought.
Congo Red and Iodine-Stained Amyloid Fibrils Studied by Negative Contrast Electron Microscopy and X-Ray Diffraction
Authors: Gueft Boris
Published: June 2020

The compound formed by addition of Congo red to suspensions of amyloid fibrils is known to be specific for amyloid and fairly stable. It is analogous to the addition or inclusion compounds of Congo red with cellulose. At one time it was suggested that the Congo red molecule with dimensions of 21 x 8.5 x 3.8 X is sequestered within the fibril. Ashkenazi and his colleagues have demonstrated that the Congo red amyloid complex forms only when the amyloid fibril has its normal sugar content, and, that the complex resists alkalai that would ordinarily remove the sugar content. The conclusion was that Congo red stains the carbohydrate moiety of amyloid.

1% aqueous Congo red was added slowly to relatively pure human liver amyloid fibril suspensions prepared from successive aqueous centri-fugations at 4,000 G of upper precipitate layers. Addition was stopped when the supernatant after centrifugation was reddish. The red precipitate was washed for 9 minutes twice in distilled water, and studied by electron microscopy before and after the addition of equal parts of 2% pH 6 potassium phosphotungstate. Amyloid controls free of Congo red were also studied. (RCA EMU 2A; carbon-coated “Formvar” grids).
Electron Microscope Studies of Anti-Antibodies
Authors: Robinson J. P. , Robinson R. D.
Published: June 2020

The presence of anti-antibodies in sera was first proposed by Najjar and Fisher in 1955. There have subsequently been numerous demonstrations of anti-antibodies and the subject was recently reviewed.

According to Najjar's proposal there should be at least two distinguishable types of antibodies involved in the formation of immune complexes. The first antibody is specific for the antigen while the second, anti-antibody, is directed against the antibody portion of the immune complex.

This report involves visualizing the anti-antibody portion of complexes by positive staining. It also demonstrates their removal from equivalence complex in acid media.

Thin sections of equivalence complex were prepared before and after partial dissociation by exposure to pH 2. 8. The sections were stained by floating on uranyl acetate solutions. Fig. 1 illustrates a preparation of equivalence complex while Fig. 2 shows the remainder of a complex partially dissociated at low pH. Equivalence complex contains large areas of interacting anti-antibodies which are detected by the absence of ferritin molecules. Such areas are greatly reduced or removed from the complex in Fig. 2. Normal γ-globulin mixed with ferritin forms no precipitate.
The Spring-Tactoid-Superspring Concept of Fibrous Proteins
Authors: Borasky Rubin
Published: June 2020

In the course of studies on the mechanics of protein synthesis it was observed that the subfibrillar elements of collagen fibrils are interwoven. Current concepts of collagen structure do not allow for this interweaving. To explain this phenomenon, therefore, I developed the “spring-tactoid-superspring” concept for the formation and structure of collagen fibrils. The purpose of this report is to summarize the essential features of this concept as it pertains to collagen and other fibrous proteins.

Fibrous proteins are copolymers. As such they are constituted of a variety of types of copolymer subunits, many of which have complementary properties. Complementarity of subunits plus favorable environmental factors in intra- and intercellular space promote coalescence of the subunits to form tactoids. These having similar characteristics as the subunits, and being affected by the same environmental factors, coalesce and because of limited intra- or intercellular space are compacted into fibrils. The fibrils, therefore, may be considered to be highly ordered complexes of compacted tactoids, the subunits of which have a lattice structure which may be defined by characteristic x-ray diffraction patterns and electronoscopic appearance. Evidence supporting this concept follows.
Electron Probe Morphological and Chemical Analyses of The Rat Epiphyseal Plate
Authors: Hagerty Jon C. , Tousimis A. J.
Published: June 2020

The electron probe affords a means not possible with previous techniques for simultaneous morphological and chemical analyses in situ on biological systems. This method of analysis has been applied to the study of the soluble and insoluble components of the epiphyseal plates of the tibias of young growing rats

Sections of both frozen dried and chemically treated, i.e. fixed and embedded, epiphyseal plates have been studied through the use of the scanning electron microscope and X-ray microanalytical capabilities of a modified electron probe. The elements Ca, P, S, K, Na, Cl, and Mg have been of specific interest in these studies on the chemical environment of the zones of the epiphyseal plate from resting to mineralization.
Morphology of Relaxed and Contractile Forms of Purified Pyocin Particles
Authors: Baechler C. A. , Higerd T. B. , Beck R. S.
Published: June 2020

Pyocin particles produced by Pseudomonas aeruginosa have been described by Ishii et al and by Higerd et al as double hollow cylinders similar to the contractile tail protein of the T-even phages of E. coli. Induction and a 1000-fold purification of the bacteriocin was accomplished as described by Higerd et al. Specimens for electron microscopy were prepared by pseudoreplication on copper grids, uranyl-magnesium acetate negative contrast, and observed in an RCA EMU-3H at instrumental magnifications of 24,000 to 50,000 diameters. Active pyocin particles in 0.02 M magnesium chloride-tris-HCl buffer pH 7.5 , are uncontracted forms (Fig. 1), 18 by 100 mμ, containing a 5 mμ diameter core which becomes evident when the particles contract (Fig. 2). Contraction can be promoted by re-suspending the particles in different selected salts or by increasing the molarity of magnesium chloride from 0.02 M to 0.5 M. The pseudoreplication technique was preferred for this study since phosphotungstate, silicotungstate, manganous chloride, and calcium chloride caused contraction, thus excluding them in specimen droplet techniques.
Fine Structure of Venus's-Flytrap Plastids
Authors: Schwab D. , Scala J. , Simmons E.
Published: June 2020

Venus's-flytrap (Dionaea muscipula) is a flowering insectivorous plant. Its leaf consists of two parts, a broad petiole and a two-lobed blade hinged down the middle. The two-lobed blade is especially suited for trapping insects and can enclose an ant in less than one second after it has stimulated two of the three sensitive trigger hairs which are located on the surface of each lobe. During a recent electron microscopic study of Venus's-flytrap it was noted that each of the four main organs (i.e. leaf, lobe, trigger hair, and digestive gland) has a characteristic plastid.

Figure 1 shows a typical chloroplast observed in the photosynthetic tissue of the flytrap leaf. The most striking feature of the chloroplasts is their lack of grana or of structures resembling the grana of other higher plants. Although some thylakoids appear on occasion to form a loose association, no evidence of even rudimentary grana has ever been observed. The thylakoids are poorly organized, but predominantly parallel and appear to go around the numerous osmiophilic globules.
Ultrastructural Features of the Sporophytic-Gametophytic Interphase in Bryophytes
Authors: Ridgway John E.
Published: June 2020

The unique feature which characterizes the bryophytes as a group is the epiphytic nature of the erect sporophytic phase upon the gametophytic phase in the plant life cycle. Since the sporophyte has no rhizoids to function in absorption, all inorganic ions, water, and initially organic metabolites are absorbed directly from the tissues of the surrounding gametophytic tissues through a specialized region of the sporophyte, the foot (Fig. 1). During dissection of living material, a mucilaginous layer is observed between the cells of the foot and the cells of the surrounding gametophytic tissue. Cytochemical tests indicate that this layer is ruthenium red positive, PAS positive, and alcian yellow positive (acid, nonsulfated polysacharrides.)