bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructure of acute lymphoblastic leukemia in ovine induced by inoculation of bovine leukemia virus.
Authors: Al-Bagdadi F. , Seger C. , Titkemeyer C.
Published: June 2020

The malignant transformation of normal cells by leukemia viruses is the subject of much current interest. It has been reported that subcutaneous inoculation or oral administation of blood from leukotic cows into sheep caused lymphoproliterative malignant tumors. The present study was undertaken to define the ultrastructure of ovine lymphocytes with lymphosarcoma induced by inoculation of bovine leukemic virus (BLV). It was also anticipated that electron microscopy would give information concerning the possible etiologic factors involved in ovine lymphosarcoma.

Twenty Louisiana native lambs were divided into three groups. The first group, six controls, were inoculated with 1 ml of tris buffer, 0.9 ml via the jugular vein and 0.1 ml was inoculated intradermally at the prescapular area. The second group, of seven, were inoculated with BLV culture at early passage, 0.9 ml via the jugular vein and 0.1 ml intradermally at the prescapular area. The third group, of seven was inoculated with BLV culture at late passage, 0.9 ml via the jugular vein and 0.1 ml intradermally at the prescapular area.
The keratinized layers as an ideal region for TEM localization of microorganisms in bovine dermatitis
Authors: Isitor G.N.
Published: June 2020

Bovine dermatitis of bacterial and viral involvement are of common occurrence in different parts of the world. The notable bovine dermatitis of both categories are dermatophilosis, lumpy skin disease and pyoderma. In terms of overall prevalence and severity, dermatophilosis is among the topmost ranking of all bovine dermatitis. It is usually a chronic dermatitis affecting most domesticated animals and man all over the world, especially in humid topical regions.

The role of the outermost keratinized layers in common bovine dermatitis, such as dermatophilosis, appear not to be fully appreciated in view of the usual assumption that the keratinized layers are solely composed of dead tissue elements. It is therefore a common practice to discard the keratinized layers during processing of skin biopsy lesions. The result is that the associated micro-organisms are hardly localized or non significantly isolated. The present report furnishes evidence indicating that the keratinized layers serve as an ideal region for the activities of micro-organisms associated with two types of bovine dermatitis clinically resembling dermatophilosis.
The response of a single spermatogonial cell type in mouse testes to HZE irradiation
Authors: Philpott D.E. , Sapp W. , Williams C. , Stevenson J. , Black S. , Corbett R.
Published: June 2020

It has been well documented that the spermatogonial cell population demonstrates a heterogeneous response to irradiation (1,5). Our previous work (3,4,5) has shown that when one observes cross sections of irradiated testis tissue at spermatogonial stage VI, the survival curve is different from that typical for a single cell response. Since we score all surviving spermatogonia in our cell counts, the results actually represent a response of several cell types. The plotted data as shown in Figure 1 shows a steeper slope at the beginning of the curve, a somewhat different slope between 20 and 80 rads, and a new increase at 80 rads. We have interpreted this to represent several cell types with different levels of sensitivity (5). This interpretation is consistent with the known increase in radiosensitivity of spermatogonia as they proceed through the cycle from stage I to stage VI. In this report, we will correlate the response of a single spermatogonial cell type with HZE particle irradiation dose and compare it to results using x rays.
Tissue reaction to and biodegradation of two different microcapsule formulations: DLPLA and DLPLGA
Authors: Visscher G. E. , Robison R. L. , Argentieri G. J.
Published: June 2020

It was our goal to characterize the tissue response to and biodegradation of microcapsules of lypressin composed of two different polymers. Microcapsules of lypressin were made with the polymer 50:50 poly (DL-lactide-co-glycolide) DLPLGA and poly (D, L-lactide) DLPLA. The work which is presented here compares the in vivo characteristics of these microcapsules as drug delivery systems.

For the study using DLPLGA, 14 groups of male rats were administered, as an intramuscular injection (gastrocnemius), microencapsulated lypressin (1%). Injections of microcapsules were examined through Day 63 of the experiment. In the second study using DLPLA, 27 male rats were injected with microcapsules of lypressin (0.4%) and examined at 30 day intervals through 420 days post injection. Light microscopy was used to characterize the tissue reaction to the injected microcapsules.
Ultrastructure of bronchopulmonary lavage cells from bovines administered 3-methylindole: II. 24 hours post-treatment
Authors: Singh Amreek , McLaren Judith M. , Atwal Onkar S. , Eyre Peter
Published: June 2020

Introduction

3-methylindole (MI), a rumen metabolite of the amino acid L-tryptophan, has been shown to produce bovine pulmonary edema and emphysema. The airways contain free and exfoliated cells. A morphologic analysis of these cells may complement the understanding of the mechanism of lung edema. Ultrastructure of the bronchopulmonary lavage (BL) cells 24 h following MI oral administration to calves is described in this experiment. The 12 hours post-treatment results were described earlier.

Materials and Methods

Two Holstein-Friesian calves were each administered an oral dose of 0.2 g MI/Kg body weight and another two calves served as controls. The animals were euthanized with sodium pentabarbitol 24 h after receiving the compound. The lungs and trachea were removed and 0.1 M sodium phosphate buffered saline was infused into the lungs through the trachea. Glutaraldehyde fixative was added to the recovered BL fluid so as to form a 1% solution. The fluid was centrifuged and the resulting cell pellet was suspended in the buffer. The procedures were repeated on the suspension; the pellet was post-fixed in osmium tetroxide and was processed by conventional methods of section preparations for TEM examination. Lung samples from caudal lobes were fixed in 1.5% glutaraldehyde to obtain tissue sections for TEM.

Results and Discussion

Pulmonary alveolar macrophages (AM), neutrophils, ciliated epithelial cells, globule leukocytes and plasma cells were recovered from the BL fluid of the control and Mi-administered calves. Ciliated cells and globule leukocytes could not be harvested from the controls. The AM obtained from the treated calves (Fig. 1) in comparison with similar cells from the controls were larger, and contained large membrane-limited inclusions (phagolysosomes). There was a remarkable similarity between the lavaged AM and the AM studied in thin sections of lung (cf. Fig. 1 and Fig. 2). The neutrophil was the second most abundant cell type retrieved from the lavage fluid from the calves of control or treated group. Except for scanty pseudopodia in the neutrophils obtained from the Mi-receiving calves, the cells appeared unaltered (Fig. 3). Ciliated cells were abundant in the BL fluid of Mi-ingesting calves. A heterogeneous collection of vesicles filled the ciliated cell cytoplasm (Fig. 3). Globule leukocytes were commonly observed among BL cells of treated calves. The globule leukocytes were ca. 15 μm in diameter and contained round or elliptical nuclei with conspicuous nucleoli. The cytoplasmic granules, which are a prominent feature of globule leukocytes, were electron-opaque and had a variable diameter (0.5-3.0 μm). A one-line account of globule leukocytes in the bronchi of steers administered MI has appeared. Plasma cells were rare. Ultrastructure of BL cells is compatible with their response to chemical insult by MI.
Ultrastructural aspects of the cell envelope of Legionella
Authors: Sun C.N. , Morgan P. , Bowen W.R.
Published: June 2020

The causal agents of Legionnaires’ Disease and related respiratory ailments in humans are gram-negative rod-shaped bacterial species belonging to the newly recognized genus, Legionella. During a comparative study of the ultrastructural organization of the cell boundary in several species, additional information regarding the presence and nature of various appendages of the cell envelope in these bacteria was observed.

Cultures of L. pneumophils (including several serogroups) and L. micdadei were grown on charcoal yeast extract agar with increased humidity at 37°C. Samples were removed after 5 days of growth and immediately fixed in either glutaraldehyde/ruthenium red (GA/RR) followed by osmium tetroxide/ruthenium red (OSO4/RR) or glutaraldehyde/tannic acid (GA/TA) followed by osmium tetroxide. Thin sections were stained with uranyl acetate and lead citrate.
Solid-phase immunoelectron microscopy for rapid diagnosis of enteroviruses
Authors: Pegg-Feige K. , Doane F. W.
Published: June 2020

Immunoelectron microscopy (IEM) applied to rapid virus diagnosis offers a more sensitive detection method than direct electron microscopy (DEM), and can also be used to serotype viruses. One of several IEM techniques is that introduced by Derrick in 1972, in which antiviral antibody is attached to the support film of an EM specimen grid. Originally developed for plant viruses, it has recently been applied to several animal viruses, especially rotaviruses. We have investigated the use of this solid phase IEM technique (SPIEM) in detecting and identifying enteroviruses (in the form of crude cell culture isolates), and have compared it with a modified “SPIEM-SPA” method in which grids are coated with protein A from Staphylococcus aureus prior to exposure to antiserum.
Labelling of non-A, non-B hepatitis infected chimpanzee hepatocytes with nuclease-gold conjugates
Authors: Gagne G. D. , Miller M. F. , Peterson D. A.
Published: June 2020

Experimental infection of chimpanzees with non-A, non-B hepatitis (NANB) or with delta agent hepatitis results in the appearance of characteristic cytoplasmic alterations in the hepatocytes. These alterations include spongelike inclusions (Type I), attached convoluted membranes (Type II), tubular structures (Type III), and microtubular aggregates (Type IV) (Fig. 1). Type I, II and III structures are, by association, believed to be derived from endoplasmic reticulum and may be morphogenetically related. Type IV structures are generally observed free in the cytoplasm but sometimes in the vicinity of type III structures. It is not known whether these structures are somehow involved in the replication and/or assembly of the putative NANB virus or whether they are simply nonspecific responses to cellular injury. When treated with uranyl acetate, type I, II and III structures stain intensely as if they might contain nucleic acids. If these structures do correspond to intermediates in the replication of a virus, one might expect them to contain DNA or RNA and the present study was undertaken to explore this possibility.
Simplified transfer of frozen-hydrated specimens into a commercially available cooling holder
Authors: Athey B. D. , Langmore J.P.
Published: June 2020

The examination of frozen-hydrated specimens maintained at liquid nitrogen (LN2) temperatures within the electron microscope is now established as an important technique to perform high resolution structural analysis of biological macromolecules. In some commercially available side-entry cold stages, it is often impossible to take advantage of this new method because hydration of the frozen specimen during grid placement and subsequent transfer of the stage into the EM makes the sample unusable. Recently, modifications to allow for frost-free transfer under LN2 have been reported for the JEOL EMSCH cooling stage, available for the JEOL JEM 100CX. Detailed below is a further change to this holder which greatly improves the reproducability of specimen transfer, reducing the time and manual dexterity needed for this process.
The mechanism of closed-system diagenesis of marine magnesium calcite: An AEM study
Authors: Blake D. F. , Lohmann K. C.
Published: June 2020

A recent focus of marine carbonate research is the determination of secular variations in paleo-ocean chemistry through the study of modern and ancient marine cements. By studying the major and minor element chemistry of marine carbonate cements, it is in principle possible to infer the chemical composition of the marine waters from which such cements precipitated. However, since most inorganically precipitated phases in the marine environment are metastable, they commonly undergo chemical and mineralogic stabilization (i.e., diagenesis) in the post-depositional environment. Such processes at low temperature require solution-reprecipitation reactions involving extraneous and generally non-marine fluids, and typically lead to a loss of the chemical information contained in the original marine carbonate cements.
Morphological and elemental analysis of isolated incubated frog retina-choroid
Authors: Panessa-Warren B. J. , Warren J. B. , Kraner H. W.
Published: June 2020

Our previous studies have demonstrated that abnormally high amounts of calcium (Ca) and zinc (Zn) can be accumulated in human retina-choroid under pathological conditions and that barium (Ba), which was not detected in the eyes of healthy individuals, is deposited in the retina pigment epithelium (RPE), and to a lesser extent in the sensory retina and iris. In an attempt to understand how these cations can be accumulated in the vertebrate eye, a morphological and microanalytical study of the uptake and loss of specific cations (K, Ca,Ba,Zn) was undertaken with incubated Rana catesbiana isolated retina and RPE preparations. Large frogs (650-800 gms) were dark adapted, guillotined and their eyes enucleated in deep ruby light. The eyes were hemisected behind the ora serrata and the anterior portion of the eye removed. The eyecup was bisected along the plane of the optic disc and the two segments of retina peeled away from the RPE and incubated.
Correlated scanning and transmission electron microscopy of Naegleria fowleri amoebastomes
Authors: Cole T. B. , Bruner R.A. , John D.T.
Published: June 2020

Naegleria fowleri is a free-living amoeboflagellate that is the causative agent of primary amoebic meningoencephalitis (PAM) in humans and is also cytopathogenic for established mammalian cell cultures. Scanning electron microscopy has shown that the focal ingestion of cultured cells is mediated by a sucker-like structure found on this amoeba. Another report also describes well-organized sucker-like structures called amoebastomes. In this report, we will correlate scanning (SEM) and transmission electron microscopy (TEM) to demonstrate the morphology and the application of the amoebastome of the invasive N. fowleri trophozoite.

Isolates of N. fowleri amoebae were grown at 30°C with Nelson medium in standard round 35x10mm plastic petri dishes. Cultured yeast cells were washed in amoeba saline and added to the amoebic cultures 3 hr prior to fixation. At 72 hr of culture age, the amoebic cultures with the added live yeast cells, were carefully rinsed with amoeba saline and fixed for 1 hr at room temperature (23°C).
Ultrastructural organization of the basal lamina in insect Malpighian tubules
Authors: Ryerse J.S.
Published: June 2020

Relatively little is known about the structure or function of the basal lamina in insect cells. I report here the ultrastructural organization of the basal lamina in Malpighian tubule yellow region primary cells of larval stage skipper butterflies (Calpodes ethlius). The Malpighian tubules selectively filter the blood and produce a primary urine which flows down the tubule lumen into the alimentary canal for excretion. The basal lamina provides the only barrier between the Malpighian tubule cells and the blood which freely circulates within the open body cavity and it may therefore regulate which molecules and ions gain access to the tubule cells. As a first step in these studies on the structure, composition and function of the basal lamina in insect cells the ultrastructure of the basal lamina in Calpodes Malpighian tubules after conventional TEM tissue processing and poststaining has been compared with that observed following en bloc staining with a variety of electron dense stains and probes with specificity for basal lamina components.
Tufts of modified microvilli of tapeworm inserted into liver tissue
Authors: Rikihisa Y. , Lin Y. C.
Published: June 2020

The surface of the tapeworm is covered with special microvilli. Since the tapeworm lacks both alimentary tract and respiratory system throughout its life history, the tegument (and its microvilli) is the major organ through which absorption of nutrients and oxygen occurs. The tegument is also extremely important for excretion and secretion, and it is the site of the recognition and reaction to the parasite by the host immune system. All of these conditions are also related to any pathologic consequences of the infection.

In this study, the early stage of experimental infection of rat liver with Taenia taeniaeformis was examined by transmission electron microscopy (TEM). Tapeworm oncospheres hatch in the rat intestine, penetrate the intestinal wall and finally lodge in the liver tissue. In the liver cyst, a larva grows in its bladder whose surface is directly apposed to the liver cells, whereas the scolex is invaginated into the sac of the bladder and protected from direct exposure to host tissue.
The formation of Ni-silicide phases on dislocations and twins in Si
Authors: Vanderwalker D. M.
Published: June 2020

The Ni-silicide cloudlike phases which form near dislocations and the edges of twin plates in Si can potentially be used as microwires. In this study, a Si specimen was compressed along a [231] axis and cooled under a high stress by the method of Wessel and Alexander. A layer of Ni was then evaporated on a slice taken parallel to the (111) surface before ageing at 260°C. The transmission electron microscopy was performed on the JEM 200CX.

TEM examinations of the structure show there are hexagonal dislocation loops and twin boundaries. The dislocation segments are confined to <110> directions. The precipitation is heterogeneous. There are two phases present, a cloudlike phase and a small spherical phase. Both phases are found to nucleate near the edges of the twin plate. The cloudlike phase is observed along the edge of the twin plate shown in figure 1.
The internal structure of medullated wool
Authors: Barish Leo
Published: June 2020

Although most of the wool used today consists of fine, unmedullated down-type fibers, a great deal of coarse wool is used for carpets, tweeds, industrial fabrics, etc. Besides the obvious diameter difference, coarse wool fibers are often medullated.

Medullation may be easily observed using bright field light microscopy. Fig. 1A shows a typical fine diameter nonmedullated wool fiber, Fig. IB illustrates a coarse fiber with a large medulla. The opacity of the medulla is due to the inability of the mounting media to penetrate to the center of the fiber leaving air pockets. Fig. 1C shows an even thicker fiber with a very large medulla and with very thin skin. This type of wool is called “Kemp”, is shed annually or more often, and corresponds to guard hair in fur-bearing animals.
Point and planar defects in the iron sulfide compounds Fe1-xS
Authors: Nguyen Thao A.
Published: June 2020

It is well known that the large deviations from stoichiometry in iron sulfide compounds, Fe1-xS (0≤x≤0.125), are accommodated by iron vacancies which order and form superstructures at low temperatures. Although the ordering of the iron vacancies has been well established, the modes of vacancy ordering, hence superstructures, as a function of composition and temperature are still the subject of much controversy. This investigation gives direct evidence from many-beam lattice images of Fe1-xS that the 4C superstructure transforms into the 3C superstructure (Fig. 1) rather than the MC phase as previously suggested. Also observed are an intrinsic stacking fault in the sulfur sublattice and two different types of vacancy-ordering antiphase boundaries. Evidence from selective area optical diffractograms suggests that these planar defects complicate the diffraction pattern greatly.
High resolution at low voltage: The SEM philosopher's stone?
Authors: Boyes E. D.
Published: June 2020

A new type of scanning electron microscope (SEM) has been designed to produce nanometre-level high resolution secondary electron images of the surfaces of uncoated non-conducting specimens such as structural ceramics, cement (Fig.1), supported catalyst particles (Fig.2), fine scale metallic features (Fig.3) including radiation damage, and eventually also biological material. Clean low voltage systems also look promising for microanalysis of surface layers e.g. Fig.4.

Very useful 5-20nm resolution images of surfaces are obtained with a conventional electron microscope operated at 25-100kV (Figs.2,3) but at these high accelerating voltages the secondary electron yield of most materials is very low, typically < 0.1, and there are therefore severe surface charging problems with non-conducting regions of specimens, the images of which are consequently of poor quality.
Thermal field emission for low-voltage SEM
Authors: Orloff J.
Published: June 2020

Low voltage SEM is an increasingly important technique for examining specimens which can be damaged by high energy electrons or which are insulators. It is particularly useful for the study of semiconductor devices and a number of specialized methods have been developed. These include voltage contrast SEM, e-beam induced conductivity, stroboscopic SEM, inspection and line width measurement. Low energy is necessary because many circuit components, especially MOS devices are easily damaged. Moreover, insulating components of circuits, including passivation layers, dictate beam energies ≲ 1 keV in order to avoid electrical charging.

The current density and brightness of a thermionic cathode are proportional to the voltage of the cathode with respect to the specimen; consequently the current which can be focused into a given beam diameter decreases with beam energy. In contrast, the current density and brightness of a field emission cathode depend on the electric field at the emitter surface, so that by the appropriate choice of gun geometry, high brightness can be attained at low beam energy.
Lithography with low-energy electrons
Authors: Newman T. H. , Pease R. F. W. , Polasko K. J. , Yau Y. W.
Published: June 2020

Two prominent problems of electron beam lithography are slow throughput and proximity effects. The former arises from the serial nature of the exposure process; the current available in a beam of given resolution is limited by electron optical considerations and the resist sensitivity is limited by material considerations such that a dose of 1 μC/cm2 at 20 kV is required for the most sensitive resist and ten times that dose if high resolution is required.

Proximity effects are caused by electrons scattered through lateral distances greater than the resolution of the pattern; a 20 keV electron in silicon has a range of about 3 μm whereas feature sizes are often less than 1 μm. Lowering the energy of the exposing electrons to, say, 2 keV would lower the electron range to less than 0.1 μm in silicon and thus effectively eliminate proximity effects as far as semiconductor circuit fabrication is concerned.
Dislocation substructure changes with stress reversal in polycrystalline OFHC Cu
Authors: Woo O.T. , Christodoulou N. , Mecke J.F.
Published: June 2020

The rearrangement of dislocations in a deforming metal during a stress reversal is thought to contribute to a lowering of the yield stress in the reverse direction. Part of the stress-strain curve of an annealed polycrystalline OFHC Cu specimen, deformed first to -118 MPa in compression and then in tension, is shown in fig.1. The workhardening rate, θp = dσ/dεp where σ is the true stress and εp the true plastic strain, is plotted against |σ| in fig.2. The compressive workhardening rate, for stresses beyond -118 MPa (point A) where the reversal was made, was obtained from a second specimen that was deformed entirely in compression. Figures 1 and 2 reveal the following: (a) the reverse proportional limit (σr) is ∽40 MPa lower than the “forward” peak stress (σf), and it requires ∽1% εp before the reverse flow stress achieves a value equal to the previous foreward maximum; (b) θp-reverse is initially higher than θp-forward, then falls below, and eventually becomes equal to θp-forward at a much higher stress than the peak forward stress.
The disordering process in an Ll2 ordered alloy
Authors: Horton J. A. , DasGupta A. , Liu C. T.
Published: June 2020

Ordered intermetallic alloys potentially have good high temperature mechanical properties which often are obtained by macroalloying. Since service temperatures may be near the critical ordering temperature, Tc, it is important to understand the disordering processes. The disordering mechanism in an alloy of 52.5 at. % Ni—22.5 Fe—14.5 V—10 Al—0.5 Ti [which can be expressed as (Ni70Fe30)3(V58Al40Ti2)], will be presented here. The aluminum was added to increase Tc from 750 to 975°C and stabilize the Ll2 structure.

All specimens were first fully ordered by a heat treatment consisting of 30 min at 1000°C, 1 d at 700°C and 2 d at 600°C which results in a “swirl” pattern of antiphase boundaries (APB) similar to Fig. 1. Specimens were then heat-treated for 24 h at temperatures from 600 to 950°C in 50°C increments and water quenched.
The role of scanning electron microscopy in studying aluminium-lithium alloys
Authors: Louise Makin P. , Ralph Brian
Published: June 2020

The use of aluminium-lithium alloys for aerospace applications is dependent on a thorough understanding of the development of the microstructure as a function of processing variables. Although a significant amount of transmission electron microscopy work has been performed on the precipitation of the low temperature metastable Al3Li phase (e.g. 1,2) information from similar studies concentrating on the equilibrium AlLi (δ) phase is limited due primarily to the reactivity of the δ causing it to etch out during electropolishing of the alloys. The conventional approach of using light microscopy to follow the grain structure development of a given alloy is also limited for non-copper containing aluminium-lithium alloys as no etch or anodising technique is able to show the detail of the unrecrystallised subgrain structure that is present in the alloys in plate or sheet form.
Effects of dislocation loop morphology in titanium on diffraction contrast
Authors: Cann C.D. , Griffiths M. , Styles R.C.
Published: June 2020

In hexagonal metals, such as Zr and Ti, both vacancy and interstitial loops may form (or develop) under neutron irradiation. These loops generally have a perfect Burgers vector, b, although faulted vacancy loops have been observed in Zr. Recently, Griffiths et al. have reported the observation of fringe contrast associated with dislocation loops in Ti. These loops had a b in the direction, but the presence of the fringe contrast was evidence that it differed from a perfect vector. An example of this fringe contrast is shown in Fig. 1. Griffiths et al. suggested two possibilities for the origin of this fringe contrast. The first was that this contrast resulted from impurities in the vicinity of these loops and the second was that the loops were faulted with . However, for both of these possibilities it was difficult to explain that the fringes were observed only under conditions of inside contrast and that fringed loops were observed in only certain grains.
Polishing process effect on the image of dispersed precipitates
Authors: Hu C.T. , Allen C.W.
Published: June 2020

One important problem in determination of precipitate particle size is the effect of preferential thinning during TEM specimen preparation. Figure 1a schematically represents the original polydispersed Ni3Al precipitates in the Ni rich matrix. The three possible type surface profiles of TEM specimens, which result after electrolytic thinning process are illustrated in Figure 1b. c. & d. These various surface profiles could be produced by using different polishing electrolytes and conditions (i.e. temperature and electric current). The matrix-preferential-etching process causes the matrix material to be attacked much more rapidly than the second phase particles. Figure 1b indicated the result. The nonpreferential and precipitate-preferential-etching results are shown in Figures 1c and 1d respectively.
Computer construction and presentation of 3D images
Authors: Liu C. N.
Published: June 2020

Three-dimensional reconstruction is a subject of considerable importance in many scientific and engineering investigations. This study is concerned with the development of new computer techniques and system by which the structures of an object are assembled for precise interpretation from their two-dimensional ultrasonic images. This paper describes a computer controlled ultrasonic scanning and data acquisition system, a set of computer algorithms for reconstructing ultrasonic attenuation from transmission scans, i.e. computerized ultrasonic tomography, and an image processing system for three-dimensional image processing and presentation. The above systems and techniques are illustrated using a simple phantom and an example of reconstructed three-dimensional image of this phantom in terms of ultasonic attenuation is presented.
Electron probe analysis, x-ray mapping and electron energy loss spectroscopy of elemental distribution inEscherichia coliB
Authors: Chang Chung-Fu , Shuman Henry , Somlyo Andrew P.
Published: June 2020

The ability of bacteria to concentrate minerals is well known, but little is known about the subcellular distribution of ions. Electron probe microanalysis, X-ray mapping and electron energy loss spectroscopy of ultrathin cryosections are particularly suitable for determining composition at the ultrastructural level in cells, including bacterial spores. In the present study, we report preliminary experiments with these methods on elemental concentrations and distribution in E. coli B, including differences in the calcium content between dividing and non-dividing cells.

E. coli B were grown in the presence of 1% tryptone (DIFCO), 0.2% glucose and 0.1M NaCl. The cells were harvested at a concentration of ∽3x108cell/ml (in the late log phase). Cells were washed in nominallv ion-free solutions and then frozen, in the presence of 10% PVP, in supercooled Freon 22 at -164°C. The specimens were freeze-dried and cryosectloned as described previously. Analyses were performed on a Gatan LN2cold specimen holder, at a temperature of -101°C. A bright-field image of the cryosectioned E. coli is shown in Fig. 1.
The theory of Gaussian deconvolution applied to EDS spectra
Authors: Hashemi Ebrahim
Published: June 2020

A limiting factor in EDS analysis has been that the resolution of Si(Li) detectors has remained above 130 eV (at 5.9 keV). However, elemental peaks separated by only a few eV are not uncommon in x-ray spectra. For such cases peak area extraction by simple integration or peak stripping can result in large errors. Peak overlap factors are useful in some applications, but the large data base required makes general application difficult.

Although the library least squares method is generally applicable, it requires many pure element or at least nonoverlapping standards. Because of the time-variance of peak shift and resolution, standard data must either be acquired at the same time as unknown data, or the electronics and software must be constantly recalibrated.
Analytical electron microscopy of a selective oxide scale formed on 20%Cr/25%Ni/niobium stabilized stainless steel
Authors: Bennett M.J. , Desport J.A. , Labun P.A.
Published: June 2020

In the United Kingdon commercial advanced gas cooled nuclear power plants the fuel cladding is a 20%Cr/25%Ni/0.7%Mn/0.7%Si/Nb stabilised (20/25/Nb) austenitic stainless steel and the coolant is CO2 based. Protection of the 20/25/Nb steel surfaces can be enhanced by selective oxidation, which ensures that a Cr-rich oxide scale covers the steel surface. The selective oxidation procedure developed was compatible with the required metallurgical annealing treatment and consisted of a lh heat treatment at 930°C in 50:1 H2/H2O. Weight gain measurements indicated that the average scale thickness was 0.5 micron.

Electron transparent transverse specimens of selectively oxidised 20/25/Nb steel were produced and the microstructure and chemical composition of the selective oxide scale was investigated by AEM techniques.
A simple clean vacuum system for carbon-film evaporation
Authors: Lamvik M.K. , LeFurgey A.
Published: June 2020

Electron microscopes with clean vacuum systems provide a contaminant-free environment for the specimen, but some of this advantage is lost if the substrate acts as a source of surface-bound contaminants. Particularly for microanalysis of thin specimens, whether by energy-dispersive x-ray spectroscopy or by electron energy-loss spectroscopy, substrates should be free of both organic and inorganic contaminants that might mask elements under Investigation. If specific heavy atom markers are to be studied by high resolution electron microscopy, the substrate should be free of extraneous heavy atoms. The substrate should be as thin and smooth as possible, and it is often helpful that the substrate films be hydrophilic, to assist the binding of some biological particles and improve the spreading of negative stains, when such stains are used.
A three-dimensional reconstruction of the complex flagellar filament of Rhizobiwn lupini
Authors: Trachtenberg S. , Aizawa Shin-ichi , DeRosier D. J.
Published: June 2020

The bacterial flagellum is composed of a basal body (the putative motor), a hook (the putative universal coupling), and a helical filament (the propellor). Based on their distinctive morphologies in the electron microscope, there are two different types of flagella: the plain flagellum and the complex flagellum. Most bacteria have plain flagella. Complex flagella are found in only a few species of bacteria: Rhizobium lupini, Rhizobium meliloti and Pseudomonas rhodos, and are associated with motility in a viscous medium.

The most prominent feature of the complex flagellum is what seems to be an outer sheath consisting of a three-stranded helical winding (Fig. 1), which is absent from plain filaments (Fig. 2, Salmonella typhimurium). The sheath, however, does not arise from the presence of an additional subunit since the complex filament (like the plain flagellum) is made from a single species of protein, flagellin.
Thin section microanalysis of zeolite Y
Authors: Hall J. B.
Published: June 2020

Zeolite Y, a remarkably stable zeolite widely used in catalyst formulations, is a synthetic aluminosilicate with the faujaslte structure. It is distinguished from zeolite X by having fewer Al atoms per unit cell and greater stability. Y can be made even more stable by further reducing the number of Al atoms per unit cell to form ultrastable Y (U.S.Y). Because the Al/Si ratio of a zeolite is an important parameter affecting its properties, knowledge of the Al and Si distribution across individual particles is also important. A study of that distribution was therefore undertaken by electron microscopy. A catalyst preparation of 40% U.S.Y and 60% alumina was also analyzed.

The samples were prepared for electron microscopy by embedding the particles in epoxy and cutting thin sections using an ultramicrotome. The thin section microanalysis was performed on a Philips 400T electron microscope equipped with a Tracor Northern TN2000 x-ray analyzer with digital beam control.
Digital x-ray mapping of catalyst particles
Authors: Lyman C. E.
Published: June 2020

Formation of 2-dimensional dot maps of x-ray intensity from various elements in a flat polished section was an early application of the scanning beam electron probe microanalyzer. The spatial resolution of those early maps was the same as the microprobe itself, about lpm. These maps were usually scanned in an analogue fashion, and there was generally enough x-ray signal to produce maps with good peak-to-background ratios. For analysis of individual catalyst particles, a scanning transmission electron microscope (STEM) must be used to obtain the required spatial resolution. However, the x-ray signal level is usually low and is collected with an energy-dispersive spectrometer which has a lower peak-to-background ratio than the wavelength-dispersive spectrometer used in the microprobe. To produce suitable high magnification x-ray maps of catalyst particles digital beam techniques were employed.
Surface structure effects of small particles
Authors: Castaño V. , Gömez A. , José-Yacamán M.
Published: June 2020

Small particles of noble metals have been widely used in catalysis. In the past, very little has been known about crystal structure of this kind of particles. However, STEM microdiffraction patterns can now provide a great deal of information concerning the morphological characteristcs of these particles. In this comunication we report microdiffraction studies of small gold particles (∼ 100 Å) grown by evaporation onto KCl substracte. This investigation was carried out by comparing theoretical diffraction patterns from wedgeshaped crystals (with and without surface vacancies) with experimental microdiffraction patterns. The theoretical calculations have been based on the multislice formulation of Dynamical Theory.

Fig. 1 shows a diffraction pattern of a gold particle. In addition of the (111) FCC zone, six forbidden reflections are clearly seen. These reflections have been observed in the past in films of gold and large gold particles.
Ultrastructural changes resembling nemaline body in congestive cardiomyopathy
Authors: Peng S.K. , Dickman P.S. , Abrams H.F. , French W. , Zamboni L.
Published: June 2020

Transvenous endomyocardial biopsy, first introduced by Konno in 1962, has been an important tool for evaluation of disease of the myocardium, and frequently provides clinically useful information. This study reports a very unusual case of congestive cardiomyopathy in which endomyocardial biopsy tissue showed ultrastructural changes resembling those of nemaline body skeletal myopathy (2).

A 60 year old man was admitted to the hospital with progressive dyspnea. He had a history of labile hypertension but was otherwise in generally good health. After admission, acute pulmonary edema developed after several days of progressive paroxymal nocturnal dyspnea. A congestive cardiomyopathy was diagnosed, as well as mild coronary artery disease. The ventricular ejection fraction was 20-30% by both echocardiogram and cardiac catheterization. There was also complex ventricular ectopy including nonsustained ventricular tachycardia. An endomyocardial biopsy was performed during transvenous catheterization.
Ultrastructural study of pituitary adenomas withy reference to variation in hormone production in 16 male patients
Authors: Caughey R.C. , Kalyan-Raman U.P.
Published: June 2020

Pituitary adenomas occur in 10-20% of the general population. These adenomas have been subclassified according to hormone production and ultrastructural features. Six different hormones are normally produced by these adenomas. This study was undertaken to subclassify pituitary adenomas ultrastructurally in male patients since these adenomas are rare in men. The ultrastructural features were compared and correlated with the hormone production that was clinically determined. A total of 16 male patients with pituitary adenomas, varying in age between 7 to 76 years, collected over a period of 7 years, were analyzed in this study. The types of adenomas were subclassified depending upon their ultrastructural features based on the criteria used by Kovacs, Horvath, and Ezrin.
Quantitative ultrastructural analysis of cirrhotic rat liver parenchyma
Authors: Buschmann R. J. , Buschmann MB. T. , Ryoo J. W.
Published: June 2020

In order to advance our understanding of the pathogenesis of liver cirrhosis and to improve our ability to diagnosis the disease, we have been carrying out objective and quantitative analyses of the histological and ultrastructural morphology of animal and human cirrhotic livers. In our original study we compared cirrhotic liver induced by simultaneous treatment with CCl4 and phenobarbital to untreated and phenobarbital-treated controls. The significance of the non-parenchymal (i.e. the non-lobular and non-nodular) components to the hypertrophy of this experimental liver cirrhosis was established. Although significant differences in parenchymal features were present, their significance to cirrhosis per se was confounded by the consequential effects of phenobarbital on the parenchymal hepatocytes. Because of the importance of liver parenchyma in liver function and because parenchyma is well sampled during human liver biopsies and therefore is well suited for diagnositc purposes, we decided to ultrastructural1y further elucidate the morphometric parameters of liver parenchyma in cirrhosis.
Stereology of liver biopsy specimens from patients with cirrhosis
Authors: Ryoo J. W. , Buschmann R. J.
Published: June 2020

Histologic evaluation of liver biopsy specimens is an invaluable tool for the diagnosis and management of liver diseases. Ultrastructural evaluation of biopsy specimens, however, has been limited and qualitative in nature. Many of the ultrastuructural changes associated with liver diseases, particularly the different stages of liver diseases like liver cirrhosis, are likely quantitative and thereby detectable morphometrically. Difficulties, however, arise from the variabilities attributable to a patient's age, to the time of biopsy, to known intralobular differences, and to drugs that the patients may be taking. In order to test the feasibility of ultrastructural morphometry in the study of liver cirrhosis notwithstanding these uncontrollable variables, we carried out a morphometric evaluation of human cirrhotic liver.
Hexavalent chromium uptake by an Arthrobacter species: Electron microscope studies
Authors: Bhatnagar R. , Coleman R. N.
Published: June 2020

Many micro-organisms are capable of taking up and accumulating specific metal ions from their environment. As a part of a study to evaluate bacterial removal of chromium from waste liquid streams, bacterial isolate (#96) identified as an Arthrobacter sp. was selected from 362 isolates and was reported to exhibit high tolerance to and uptake of chromium VI as determined by chemical methods.2 The present report describes fine structural studies of #96 with Transmission Electron Microscopy (TEM) and Scanning Transmission Electron Microscopy (STEM) to further understand the location of chromium accumulation and uptake. Attempts have been made to localize chromium on/in bacterial cells using Energy-Dispersive X-ray Microanalysis (EDX) and elemental mapping.
Methods for making stereoslides and -prints, with freeze-etched olfactory epithelium as example
Authors: Menco Bert Ph. M. , Menco Ido F. , Verdonk Frans L.T.
Published: June 2020

Previously we presented an extensive study of the distributions of intramembranous particles of structures in apical surfaces of nasal olfactory and respiratory epithelia of the Sprague-Dawley rat. For the same structures these distributions were compared in samples which were i) chemically fixed and cryo-protected with glycerol before cryo-fixation, after excision, and ii)ultra-rapidly frozen by means of the slam-freezing method. Since a three-dimensional presentation markedly improves visualization of structural features micrographs were presented as stereopairs. Two exposures were made by tiling the sample stage of the electron microscope 6° in either direction with an eucentric goniometer. The negatives (Agfa Pan 25 Professional) were reversed with Kodak Technical Pan Film 2415 developed in D76 1:1. The prints were made from these reversed negatives. As an example tight-junctional features of an olfactory supporting cell in a region where this cell conjoined with two other cells are presented (Fig. 1).
The distribution of calsequestrin in rat myocardial sarcoplasmic reticulum
Authors: Jorgensen A. O. , Shen A. C.-Y. , Campbell K. P. , Denney G.
Published: June 2020

We have previously identified and purified calsequestrin from canine ventricular muscle. Immunofluorescence localization suggested that cardiac calsequestrin is confined to the lumen of the interior and peripheral junctional sarcoplasmic reticulum (SR) in adult mammalian ventricular myocardial cells. Immunolocalization of calsequestrin in myocardial cells without transverse tubules (chicken ventricular myocardial cells and sheep Purkinje fibers) clearly showed that calsequestrin as predicted was present in the lumen of peripheral junctional SR but absent from the lumen of the network SR. However, in addition calsequestrin was also present in the lumen of the corbular SR, bulbous ends on the network SR mostly confined to the I band region of myocardial cells.
Electron microscopic cytochemistry of membrane-bound enzymes of cultured aortic cells treated with cholesterol oxidation derivatives
Authors: Peng S.K. , Hill J.C. , Morin R.J. , Safarik J.
Published: June 2020

Spontaneous oxidation of cholesterol occurs in the presence of air at room temperature. Certain oxidation derivatives of cholesterol have been shown to be cytotoxic to a variety of cells in culture, including vascular smooth muscle cells. These compounds may, therefore, be atherogenic, particularly in view of the probable important role of vascular smooth muscle cells in initiation of atherogenesis. The mechanism of their cytotoxicity may be directly related to their potent inhibition of cholesterol biosynthesis in cultured cells which may result in depletion of the cholesterol in cell membranes; this in turn could affect a number of important membrane functions, including permeability to metabolites, endocytosis and the activities of membrane bound enzymes, eventually leading to cell death. In the present study, the effect of cholestane-3β,5α,6β-triol and 25-hydroxycholesterol, the two most cytotoxic oxidation derivatives of cholesterol, on membrane bound enzymes in cultured rabbit aortic smooth muscle cells was investigated.
Three-dimensional reconstruction from serial, electron microscopic autoradiographs of dividing rod precursors in the goldfish retina
Authors: Raymond Pamela A. , Rivlin Patricia K.
Published: June 2020

When larval goldfish hatch, their retinas contain postmitotic, undifferentiated cones but no rods. Cones rapidly differentiate during the first few days of larval life. Meanwhile, rods begin to appear; they are produced by dividing, specialized progenitors - rod precursors - scattered across the retina. Rod precursors continue to divide throughout larval and into adult life, adding new rods to the growing retina. These dividing cells, intercalated among differentiated retinal neurons, are unique and have not been described previously. The purpose of this study was to identify rod precursors in the larval retina, to characterize them ultrastructurally and to reconstruct their morphology.

Dividing rod precursors were labeled by 3H-thymidine injections in late larval/early juvenile goldfish (26-51 days posthatch). Survival times ranged from 1 to 48 hours; fish were decapitated, the corneas were punctured with an insect pin and the eyes (or whole heads) were fixed by immersion in a mixture of 3% glutaraldehyde, 3% paraformaldehyde, 0.1% picric acid, 1 mM calcium chloride, 0.1 M phosphate buffer (pH 7.4) with 5% sucrose.