bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron Microscopic Evidence for Membrane Bound Structures in Plant Vacuoles
Authors: Thomson W. W. 
Published: June 2020

To date, most electron microscope studies of mature plant tissue have shown the vacuole to be generally devoid of internal structure except for irregular aggregates of electron dense granular material. However, after gluturaldehyde-osmium fixation, membrane bound structures are frequently observed in the vacuoles of the mesophyll cells of the xerophytic plant,Tamarix(Fig. 1). These structures are generally ovoid in shape and range in length from .5 to 1.6 μ.Some of the membrane bound, vacuolar inclusions are bounded by two membranes which are often tightly opposed (Fig. 2, arrow). Other inclusions are bounded by a single tripartate membrane (Fig. 3). The internal organization of the inclusions consists of tubules surrounded by an electron-translucent matrix (Fig. 2 & 3). The tubules measure about 350 A in diameter and frequently extend in arrays parallel to the bounding membrane. Occasionally vesicles about 1000 A in diameter are also observed in the inclusions (Fig. 1).
Further Observations on the Virus of Epizootic Diarrhea of Infant Mice. An Electron Microscopic Study
Authors: Banfield W. G. , Kasnic G. , Blackwell J. H. 
Published: June 2020

An ultrastructural study of the intestinal epithelium of mice infected with the agent of epizootic diarrhea of infant mice (EDIM virus) was first performed by Adams and Kraft. We have extended their observations and have found developmental forms of the virus and associated structures not reported by them.Three-day-old NLM strain mice were infected with EDIM virus and killed 48 to 168 hours later. Specimens of bowel were fixed in glutaraldehyde, post fixed in osmium tetroxide and embedded in epon. Sections were stained with uranyl magnesium acetate followed by lead citrate and examined in an updated RCA EMU-3F electron microscope.The cells containing virus particles (infected) are at the tips of the villi and occur throughout the intestine from duodenum through colon. All developmental forms of the virus are present from 48 to 168 hours after infection. Figure 1 is of cells without virus particles and figure 2 is of an infected cell. The nucleus and cytoplasm of the infected cells appear clearer than the cells without virus particles.
A Method for Electron Microscopic Study of Tissue Culture Cell Monolayers Grown in Tubes
Authors: Stephens R. , Schidlovsky G. , Kuzmic S. , Gaudreau P. 
Published: June 2020

The usual method of scraping or trypsinization to detach tissue culture cell sheets from their glass substrate for further pelletization and processing for electron microscopy introduces objectionable morphological alterations. It is also impossible under these conditions to study a particular area or individual cell which have been preselected by light microscopy in the living state.Several schemes which obviate centrifugation and allow the embedding of nondetached tissue culture cells have been proposed. However, they all preserve only a small part of the cell sheet and make use of inverted gelatin capsules which are in this case difficult to handle.We have evolved and used over a period of several years a technique which allows the embedding of a complete cell sheet growing at the inner surface of a tissue culture roller tube. Observation of the same cell by light microscopy in the living and embedded states followed by electron microscopy is performed conveniently.
Ultrastructural Hepatic Changes Induced by Electrocution
Authors: Schofield B. H. , Grossman I. W. 
Published: June 2020

During the course of investigations of ballistic trauma-induced hepatic changes in the goat, cytoplasmic hepatic cell vacuolization was observed in those animals killed by electrocution. To determine the pathogenesis of these vacuoles six castrated Texas Angora goats (Capra hircus) were electrocuted with 60 cycle a-c, 120 ± 5 volts, wall current with a rectal electrode and tongue electrode. Three goats killed with intravenous pentobarbital served as control animals.We consistently observed hepatic cell cytoplasmic vacuolization by light and electron microscopy in the electrocuted goats (Figure 1 and Figure 2). These vacuoles were bounded by a single smooth-surfaced membrane and a thin rim of amorphous cytoplasmic ground substance. The vacuoles occasionally distended the hepatocytes and measured up to 18μ in greatest diameter.
Some Structural Features of Metaphase Chromosomes of Mice and Men
Authors: Hoskins Godfrey C. , Hoskins Betty B. 
Published: June 2020

Metaphase chromosomes from human and mouse cells in vitro are isolated by micrurgy, fixed, and placed on grids for electron microscopy. Interpretations of electron micrographs by current methods indicate the following structural features.Chromosomal spindle fibrils about 200Å thick form fascicles about 600Å thick, wrapped by dense spiraling fibrils (DSF) less than 100Å thick as they near the kinomere. Such a fascicle joins the future daughter kinomere of each metaphase chromatid with those of adjacent non-homologous chromatids to either side. Thus, four fascicles (SF, 1-4) attach to each metaphase kinomere (K). It is thought that fascicles extend from the kinomere poleward, fray out to let chromosomal fibrils act as traction fibrils against polar fibrils, then regroup to join the adjacent kinomere.
Functional Interpretations of Mitochrondrial Structure in Tissue
Authors: Haydon G. B. , Smith S. O. 
Published: June 2020

The functional state of mitochondria at the moment of fixation may be inferred from their morphological conformation. When incubated in a medium which does not support oxidative phosphorylation, isolated mitochondria have the ordinary appearance, but after incubation in a medium which supports oxidative phosphorylation such mitochondria appear condensed.Near the surface of fresh rat heart muscle, which has been fixed in glutaraldehyde, formaldehyde or osmium tetroxide, occasional groups of mitochondria have a condensed form (Fig 1) while others have the ordinary appearance. Variations from compact to ordinary mitochondria along the tissue surface suggest that at any one time neighboring mitochondria may be in different functional states. However, all mitochondria more than ten to twenty microns from the surface of the tissue block appear ordinary suggesting that these mitochondria were all in an inactive metabolic state when fixation was completed (Fig 2). Perhaps a front of fixative solution permeates the deeper portions of the tissue and stops the oxidative phosphorylation of all mitochondria before actual fixation takes place.
Formation and Ultrastructure of the Collagen Fibril—Rubin Borasky
Authors: Borasky Rubin , Sturgeon David B. 
Published: June 2020

Although much is known about the chemistry and molecular organization of collagens there is a gap in the knowledge concerning the characteristics of the collagen fibril precursors (CFPs) synthesized in the fibroblast and how they are assembled into fibrils in intercellular space. Studies on the amino acids distribution profiles and structural defects of collagen fibrils, supported by chemical analyses and the concept of “macranolecular micelles” as monomeric units of fibrous proteins, permits the formulation of the following hypothesis for the formation and structure of the collagen fibril.The CFPs or basic subunits of collagens, synthesized in the fibroblast and discharged into intercellular space, have the following properties. They vary in kind according to their amino acid composition and primary structure. They have molecular weights ranging from about 20,000 to 40,000 and consist of from about 150 to more than 300 amino acid residues. Many CFPs are polar in that they have amino acid residues the side chains of which carry charge.
Fine Structure of the Integument of the Cryptocotyle Lingua Redia
Authors: Krupa P. L. , Bal A. K. , Cousineau G. H. 
Published: June 2020

Recent electron microscope studies of trematode rediae have revealed microvilli projecting from the integument, presumably to facilitate exchange of materials between the parasite and the snail host. This report on the redia of Cryptocotyle lingua extends these observations and provides an additional basis for future biochemical studies of host-trematode relations. The rediae were removed from crushed snails (Littorina littorea), washed in filtered sea water, fixed in 5% glutaraldehyde-paraformaldehyde solution in sea water, postosmicated, and embedded in Epon in the usual manner.Light microscopy shows that the apical surface of the redial body wall has numerous undulations or corrugations of varying dimensions and shapes (Fig. 1, arrow). As seen in the electron microscope, many cytoplasmic projections or microvilli stem perpendicularly from these crests and valleys (Figs. 2,3). In tangential sections of the redial surface (Fig. 4), the microvilli appear as thin, flat structures or spatulae, rather than as cylindrical, digitiform projections. The expanded surface of some microvilli is also suggested in sagittal- sectioned rediae (Fig. 2).
Extralysosomal Destruction of Disrupted Bacterial Cells
Authors: Roth Ivan L. 
Published: June 2020

It has been well established that the process of phagocytosis involves the enclosure of the phagocytized entity in a membrane limited vacuole called a phagocytic vacuole or phagosome.In studying the ultrastructural aspects of Bacillus anthracis (anthrax) infections in mouse spleen, it has been found that the phagosome membrane is present around avirulent (non-capsulated) anthrax cells as shown in Figure 1 (M). However, the phagosome membrane has never been seen around virulent (capsulated) anthrax bacilli. This absence of the phagosome membrane around virulent cells might be due to the exotoxin produced by Bacillus anthracis. However, the phagosome membrane is absent even around virulent anthrax bacilli which have been killed by autoclaving (Fig. 2). Perhaps the destruction of the phagosome membrane is due to the surface character of the capsule.
Electron Microscopy: The High Voltage Approach
Authors: Hart Raymond K. 
Published: June 2020

In recent years there has been considerable interest in microscopes which operate at accelerating potentials well above the now conventional level of 100 kV. The use of these high voltage instruments in both biological and physical research offers substantial advantages over what can be realized with their lower voltage counterparts.There are three aspects to very-high voltage microscopy that make it inviting: these are the presently demonstrated or expected improvements in image contrast, resolution and the thickness of specimens that can be viewed.
Oxidation of HCP Zirconium in the Electron Microscope
Authors: Bigelow W. C. , Hayes W. J. , Allard L. P. , Rowe Anne 
Published: June 2020

A reaction stage designed in this laboratory for carrying out gas-solid reactions inside the electron micrpscope was described at the 24th Annual Meeting of the Electron Microscopy Society of America. Purified gas from an auxiliary line is brought into the microscope column and carried through a Teflon tube and slots in the walls of the stainless steel reaction chamber onto both sides of the thin film specimen. The image may be recorded directly on motion picture film as the reaction proceeds.Earlier work using this stage was carried out on copper films showing wide stacking faults and surface terraces produced by annealing the metal before removal from the NaCl substrate; in subsequent treatments with oxygen the nucleation and growth characteristics of cuprous oxide were observed. Zirconium was selected for study in the high temperature reaction stage as an example of a metal having a hexagonal closest packed structure in which the effect of thermal anneal should be quite different from that in face-centered cubic materials.
Clustering of Irradiation Produced Defects near Boundaries in Molybdenum
Authors: Mastel B. , Brimhall J. L. , Bierlein T. K. 
Published: June 2020

The microstructures of molybdenum containing ∼10 ppm carbon irradiated at 60°C to a neutron fluence of 1 × 1019 n/cm2 (E < 1 MeV) and subsequently annealed at elevated temperatures were compared with microstructures of similar material irradiated at 600°C and subsequently annealed.Small defect clusters 50Å in diameter form in molybdenum during irradiation at 60 °C. These clusters are uniformly distributed throughout the sample and are believed to be interstitial in character. During a two hour anneal at 575°C cluster density decreases uniformly and cluster size increases somewhat. After a two hour anneal at a sufficiently high temperature, 900°C, all clusters disappeared. Denuding of clusters adjacent to grain boundaries was not observed after any of the isochronal annealing treatments in temperature steps of 100°C.
Direct Observation of Heat Exchanger Deposits by Cross Sectioning
Authors: Anderson R. W. , Senecal D. L. 
Published: June 2020

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.
Application of Scanning Electron Microscopy to Medical Research
Authors: Hutchison J. D. 
Published: June 2020

When the transmission electron microscope was commercially introduced a few years ago, it was heralded as one of the most significant aids to medical research of the century. It continues to occupy that niche; however, the scanning electron microscope is gaining rapidly in relative importance as it fills the gap between conventional optical microscopy and transmission electron microscopy.IBM Boulder is conducting three major programs in cooperation with the Colorado School of Medicine. These are the study of the mechanism of failure of the prosthetic heart valve, the study of the ultrastructure of lung tissue, and the definition of the function of the cilia of the ventricular ependyma of the brain.
Scanning and Transmission Electron Microscopy of Human Red Blood Cells
Authors: Tousimis A.J. , Padden T.R. 
Published: June 2020

The size, shape and surface morphology of human erythrocytes (RBC) were examined by scanning electron microscopy (SEM), of the fixed material directly and by transmission electron microscopy (TEM) of surface replicas to compare the relative merits of these two observational procedures for this type specimen.A sample of human blood was fixed in glutaraldehyde and washed in distilled water by centrifugation. The washed RBC's were spread on freshly cleaved mica and on aluminum coated microscope slides and then air dried at room temperature. The SEM specimens were rotary coated with 150Å of 60:40- gold:palladium alloy in a vacuum evaporator using a new combination spinning and tilting device. The TEM specimens were preshadowed with platinum and then rotary coated with carbon in the same device. After stripping the RBC-Pt-C composite film, the RBC's were dissolved in 2.5N HNO3 followed by 0.2N NaOH leaving the preshadowed surface replicas showing positive topography.
Design and Application of a High Voltage Transmission Scanning Electron Microscope
Authors: Cowley J. M. , Strojnik A. 
Published: June 2020

A transmission scanning electron microscope operating at voltages up to 600 kV has been built in this laboratory. Initial tests of the performance have been encouraging although the optimum performance has not yet been achieved. Developments and modifications of the instrument are now in progress in order to extend its range of applications and improve its output.The high voltage power supply and electron accelerator have been described previously. A combination of insulating oil and solid dielectric i s used to decrease leakage. This allows the high voltage unit to be compact, highly stable and inexpensive. It has proved to be reliable and trouble-free in operation.
High Resolution Goniometer Stage for Electron Microscope
Authors: Mikaziri A. , Ohomori S. , Yamamoto T. 
Published: June 2020

The performance of a goniometer stage to an electron microscope may be evaluated from several view points, such as operational easy, stability and resolving power. Stability is the fundamental, however. As is often experienced, the incorporation of a specimen tilting mechanism into the specimen chamber causes a functional unstability of the instrument and also causes inconvenience in the design of the objective lens. The top entry goniometer stage has an advantage in mechanical and thermal stability, since the specimen and specimen shifting stage are symmetrically supported around the optical axis. This supporting system is the main difference from that of the side entry goniometer stage. In the latter, the vibration and thermal drift of the specimen is unavoidable, in principle, due to an unbalanced specimen support.We have recently developed a top entry goniometer for the JEM-100B Electron Microscope, taking these points into account to meet the demand for high resolving power: this goniometer is of double tilt type, permitting each axis to tilt by ±30° and enabling the specimen to tilt around some composite tilting axis by ±40°.
Direct Observations of Twinning Dislocations in Iron Single Crystals
Authors: Ogawa Keiichi , Takeuchi Tomoyuki 
Published: June 2020

Experimental confirmations so far obtained of twinning dislocations in bcc metals have been limited to the observation of the phase change in the stacking fault fringe contrast. In the present experiments, twinning dislocations in iron crystals have been directly observed by their strain field contrast.Deformation twins were introduced into iron single crystals (1.8x6 mm2 in cross section) by an impact compression along <110> at 78°K. The compressive strain given was about 4%. The twinned specimens were mechanically sliced nearly parallel to the twin boundary {112} by a slitting saw. After mechanical polishing by emery paper, these slices were chemically polished to remove the damaged surface layers. The final thinning was performed by both jet and electrolytic polishing.
Shock Hardened and Annealed Type 316 Stainless Steel
Authors: Gelles S. H. 
Published: June 2020

The structure of shock hardened Type 316 stainless steel has been examined by transmission electron microscopy in a number of different conditions involving variations in shock pressure, temperature, and post-shock annealing in an effort to correlate changes in mechanical properties with structural changes. The samples for microscopy were prepared by careful slicing from 1/2-inch-thick shock-hardened plate, the plane of the slice being parallel to the shock wave propagation direction. This was followed by dimpling in a 60 percent H3PO4-40 percent H2SO4 bath at 125 °C, and electrolytic polishing to break-through in the same solution at 70 °C.Increasing the shock wave pressure from 0 to 320 kbar at ambient temperature produced structures with increasing dislocation densities. At 80 kbar, the easily-resolvable dislocations were relatively straight and lay in arrays on{111} [-planes as shown in Figure 1. At the 320 kbar pressure level, twin-like features formed (Figure 2) and were accompanied by a fine dislocation structure consisting in part of a high concentration of dislocation loops.
Direct Observation of the Diffusionless β → β + ω Transformation in Titanium Alloys
Authors: Paton N. E. , de Fontaine D. , Williams J. C. 
Published: June 2020

The electron microscope has been used to study the diffusionless β → β + ω transformation occurring in certain titanium alloys at low temperatures. Evidence for such a transformation was obtained by Cometto et al by means of x-ray diffraction and resistivity measurements on a Ti-Nb alloy. The present work shows that this type of transformation can occur in several Ti alloys of suitable composition, and some of the details of the transformation are elucidated by means of direct observation in the electron microscope.Thin foils were examined in a Philips EM-300 electron microscope equipped with a uniaxial tilt, liquid nitrogen cooled, cold stage and a high resolution dark field device. Selected area electron diffraction was used to identify the phases present and the ω-phase was imaged in dark field by using a (101)ω reflection. Alloys were water quenched from 950°C, thinned, and mounted between copper grids to minimize temperature gradients in the foil.
Nucleation and Growth Characteristics of Thin Metal Films
Authors: Singh H. P. , Murr L. E. 
Published: June 2020

This paper reports observations of nucleation and growth characteristics of thin metal films vapor deposited onto heated sodium chloride substrates. An attempt is made to explain the differences in nucleation and growth characteristics on the basis of classical nucleation theory.Thin metal films were prepared by vapor deposition onto heated NaCl (001) substrates in a commercial vacuum unit using a constant evaporation rate of approximately 1000 Å/sec. In the case of discontinuous thin films, approximately 200 Å of carbon was deposited for support. Samples for electron microscopy were prepared by standard techniques and were observed at 125 kV. Figs. 1(a) to (c) show a growth sequence of gold thin films characterized by 1) the formation of random, three dimensional, isolated nuclei at initial deposition, and their growth with further deposition predominantly by surface diffusion; 2) coalescence of these nuclei forming bigger islands; 3) the flattening of islands and formation of network structure : and 4) the filling up of these network structures with further deposition forming a continuous film.
The Clinical, Roentgenological and Morphological Effects of an Acute Exposure of Phosgene on the Lungs of Dogs
Authors: Bils R. F. , Diller W. F. , Huth F. 
Published: June 2020

Phosgene still plays an important role as a toxic substance in the chemical industry. Thiess (1968) recently reported observations on numerous cases of phosgene poisoning. A serious difficulty in the clinical handling of phosgene poisoning cases is a relatively long latent period, up to 12 hours, with no obvious signs of severity. At about 12 hours heavy lung edema appears suddenly, however changes can be seen in routine X-rays taken after only a few hours' exposure (Diller et al., 1969). This study was undertaken to correlate these early changes seen by the roengenologist with morphological alterations in the lungs seen in the'light and electron microscopes.Forty-two adult male and female Beagle dogs were selected for these exposure experiments. Treated animals were exposed to 94.5-107-5 ppm phosgene for 10 min. in a 15 m3 chamber. Roentgenograms were made of the thorax of each animal before and after exposure, up to 24 hrs.