bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aggregation Studies: MR and MA With Poxvirus
Authors: Sharp D. G. , Kim Kwang Soo 
Published: June 2020

The only instrument that gives direct information about virus-cell interaction at the individual particle level is the electron microscope. The counting of virus particles sedimented from dilute suspension for electron microscopy showed first that rather few of them produce plaques. Soon it was shown that the quality factor (Q=PFU/particles) was not a constant. It changed during the repeated passages required for adaptation of a virus to growth in a new host cell. More recently changes in Q have been observed when changes are made in the state of aggregation of the virus particles. These changes, their measurement and their meaning are the substance of this paper.Virus particles sedimented from dilute suspension fall upon a flat surface producing a pattern that shows coincidence pairs, triplets, etc., produced by chance falling together of separate particles. The number of these is small and it can be calculated. Aggregation in excess of this amount is true aggregation. It is the actual state of the virus particle population that encounters the cells of the monolayer on which plaques appear. From electron micrographs the frequency Ni of groups containing i particles is determined together with the total number of particles.
Electron Microscopy of the Hemagglutinin of Infectious Bronchitis Virus
Authors: Nazerian K. , Cunningham C. H. 
Published: June 2020

Infectious bronchitis virus (IBV) does not cause hemagglutination unless modified by trypsin, or ether or selectively eluted from diethylaminoethyl (DEAE)-cellulose.The virus in allantoic fluid is spherical averaging 110 mμ in diameter (Figure 1) and has club shaped spikes or projections on the surface. When treated with 1% trypsin for 30 minutes at 56° the virus is capable of hemagglutinating fowl erythrocytes. This treatment removes the spikes from the surface of the virus (Figure 2) and destroys an inhibitor of hemagglutination activity in allantoic fluid. It is not known whether changes on the surface of the virus are necessary or destruction or alteration of the inhibitor molecule by trypsin is adequate for induction of hemagglutination by IBV. The latter, however, is necessary since normal allantoic fluid inhibits the already induced hemagglutination activity of the virus.Treatment of the virus with ether removes the spikes and partially disrupts the virion (Figure 3) but no rosette-shaped particles are released, although such a treatment induces the hemagglutination activity of the virus (1).
Crystalline Arrays of Foot-and-Mouth Disease Virus in Tissue Culture Cells
Authors: Breese S.S. , Graves J.H. 
Published: June 2020

The formation of crystalline arrays of foot-and-mouth disease virus (FMDV) particles in swine kidney tissue culture cells has been examined in greater detail following the initial report of strain A119 in pig kidney cell line cultures, PK15. In the present experiments, FMDV strains recently isolated from field outbreaks in Argentina (A1, O2 and C3 CANEFA) were inoculated into primary swine kidney tissue cultures and samples at suitable intervals for embedding, sectioning and electron microscopy.The three strains of FMDV were stored at -20°C as the sixth bovine kidney tissue culture passage of original tongue tissue suspension. Immediately prior to use, they were inoculated into bovine kidney cultures and 1 ml of infected cell suspension was used in each swine kidney prescription bottle. After l/2 hr incubation at 37°C, 5 to 10 ml of maintenance medium was added and the bottles stored at 37°C. At intervals of 90 min, 3, 4, 5 and 6 hr after inoculation, bottles were processed for electron microscopy. Fluids were removed and the cells gently scraped from the glass into a few ml of Sorenson’s buffer at pH 7.2. Fixation was in 1% glutaraldehyde followed by 2% osmium tetroxide, dehydration, and embedment in epon. Sections were examined in an RCA-EMU-3-G microscope.
Electron Microscopic Studies of Virus Associated With L1210 Leukemia
Authors: Chopra H. C. , Schidlovsky G. , McBride T. 
Published: June 2020

Lymphocytic leukemia L1210 was orignially induced in female DBA mice by painting the skin surface with 0.2% methylcholanthrene in ethyl ether. It is continuously passed in DBA, C57bl/c and BDF mice by inoculating ascites cells intraperitoneally, intramuscularly or subcutaneously. It is commonly used for biochemical studies as well as for assays of chemotherapeutic agents.Our electron microscopic studies demonstrated a virus with morphological characteristics peculiar to both type B and C virus particles. Cells of ascitic fluids, spleen, lymph nodes, thymus and bone marrow of leukemic mice revealed the presence of groups of intracytoplasmic A particles (Fig. 1) identical to those seen in mouse mammary tumors. Some cells also revealed intracisternal A particles identical to those in plasma cell tumors.
In Situ Electron-Microprobe Analyses of Tissue Cultures Grown on Glass
Authors: Landstrom D. K. , Johnsson-Hegyeli R. I. , Hegyeli A. F. 
Published: June 2020

The electron microprobe has found several applications in medicine and biology. These were recently reviewed by Tousirnis. He and others have shown it to be useful for the localization of Ca, P, Fe, Ag, Zn, Cr, and Sn in normal and diseased tissues. The majority of these studies were conducted on histological sections, several cells thick, with the cells cut in different planes, and overlapping one another.This paper reports on the analysis of cells grown in a horizontal monolayer. The cells are left intact, and are analyzed on the coverslip on which they are grown. L-929 fibroblasts and KB carcinoma cells were grown on 10 x 50-mm Bellco glass coverslips in Leighton tubes. The culture medium was Hanks' Basal medium of Eagle, supplemented with penicillin, streptomycin, and 10 percent calf serum. The cultures were incubated at 37 C in a horizontal position for periods up to 3 days. They were then fixed with absolute methanol for 10 seconds, washed with several changes of distilled water, and dried. The cultures were prepared for analysis by vacuum deposition of 100 A of elemental carbon.
Ultrastructural Studies of Human Erythrocytes Following Exposure to Hemolytic Agents
Authors: Minick O. T. , Jibril A. O. , Volini F. , Kent G. 
Published: June 2020

Ultrastructural studies were carried out in human erythrocytes following exposure to a number of agents known to affect the cellular membrane; these included Retinol, p-chloromercuribenzoate (pCMB), Iodoacetate (IAc) and Neuraminidase.Erythrocytes treated with retinol revealed two types of inclusions, electron lucid and electron opaque bodies (Fig. 1). The latter often protruded from the surface and were mostly associated with the membrane, while the former more often were within the cell, away from the cell membrane. That both types of bodies could be truly intracellular in location was shown by serial sections. Addition of ferritin to the incubation medium and its appearance in electron lucid bodies indicated a pinocytosis-like process as mode of formation of the latter structures (Fig. 2). The electron dense bodies, by contrast, appeared to represent membrane alterations occasionally causing surface invagination.
The Distribution of a Particulate Component of Membranes in Brain and Retina
Authors: Someda Kuniyuki , Weinstein Ronald S. 
Published: June 2020

Replicas of fracture faces along a variety of frozen membranes have revealed a particulate component, with replicas of individual particles measuring 100 to 200 Å in diameter. The relation of these small particles to membrane ultrastructure is questionable and there is even some controversy as to whether the particles represent true membrane components, material adsorbed onto membranes from adjacent compartments, or a contaminent adsorbed onto the frozen fracture face prior to replication with carbon and platinum. In this study, replicas of fracture faces of frozen nervous tissue were surveyed in an effort to find if consistent patterns of particle distribution could be demonstrated on nervous system membranes.Rat retinas, cerebral cortex and corpus callosum were protected with glycerol or dimethylsulfoxide and freeze-fractured with a razor blade in a three tier apparatus as described in detail by Bullivant and Ames.1 Following replication in an evaporator (Kinney PW 400), the tissue was dissolved and fragments of replica were washed, picked up on grids and examined in the electron microscope. No etching, as it is defined by Moor, was involved in producing these fracture faces for replication.
Phase Contrast Images of Periodic and Quasi-Periodic Objects
Authors: Komoda T. 
Published: June 2020

The phase contrast effect due to defocussing of an objective lens is decisive factor for imaging of molecular details in electron microscopy. The effect was intensively investigated by Thon) for amorphous objects. The present report is concerned with the phase contrast effect for the objects having periodic structures such as crystals and that of quasiperiodic ones.The contrast of the electron microscopic image has been theoretically treated by Hanszen) within the frame of the optical transfer theory. Phase contrast images are explained with a phase contrast transfer function, which shows the selective imaging of Fourier spectrum of spacial frequencies (reciprocal of periods) in the potential distribution in the object. The function diminishes under the conventional operating condition of the electron microscope. Fluctuation of focus and angular divergence of the illuminating beam are predominant factors for the diminishing.
Electrical and Control Systems for the One Million Volt U.S. Steel Microscope
Authors: Libbey R. L. 
Published: June 2020

The electrical control systems for the column of the United States Steel Million Volt Microscope are designed to give the microscopist simple, yet versatile, one-man operation. The achievement of this goal was especially difficult because of the separate HV supply and accelerator, the necessity for remote control and the extremely wide range of operation. Even so, the control functions and operation closely resemble a conventional electron microscope.One of the unique characteristics of this instrument is the required alignment of the accelerator with the microscope. This alignment is aided by a motor-driven, retractable primary screen which is viewed with a television camera and displayed on a monitor in the control console. Column alignment is aided by deflection coils similar to conventional gun and condenser tilt deflectors but driven by special transistorized bridge circuitry. At the push of a button, a third set of coils combines with the condenser deflectors to give dark-field operation. It is possible to switch back and forth without adjusting controls. Apertures are motor driven and have coded pilot lamps to indicate position.
Electron Microscopy of Irradiated and Mechanically Tested Tungsten
Authors: Rau Robert C. , Ladd Robert L. , Moteff John 
Published: June 2020

As part of a program investigating the effects of neutron irradiation on the physical and mechanical properties of body centered cubic refractory metals, transmission electron microscopy has been carried out on irradiated tungsten after tensile and creep-rupture testing. These observations have shown the existence of a fluence threshold region between 5.9 × 1018 and 3.8 × 1019 nvt (E < 1 MeV) over which both microstructure and mechanical properties undergo abrupt changes.A series of specimens irradiated at pile ambient temperature (∼ 70°C) to various fast neutron fluences and subsequently tensile tested at 400°C showed dramatic evidence of the build-up of defect clusters with increasing exposure. The starting microstructure present in undeformed button heads of unirradiated control specimens consisted of large tungsten grains divided into many small subgrains by hexagonal dislocation networks, as shown in Figure 1. Irradiation to neutron fluences of 4.0 and 5.9 × 1018 nvt produced tiny dot clusters in the matrix, as shown in Figure 2.
The Microstructure of Shock-Synthesized Diamond
Authors: Trueb Lucien F. 
Published: June 2020

A new type of synthetic industrial diamond formed by an explosive shock process has been recently developed by the Du Pont Company. This material consists of a mixture of two basically different forms, as shown in Figure 1: relatively flat and compact aggregates of acicular crystallites, and single crystals in the form of irregular polyhedra with straight edges.Figure 2 is a high magnification micrograph typical for the fibrous aggregates; it shows that they are composed of bundles of crystallites 0.05-0.3 μ long and 0.02 μ. wide. The selected area diffraction diagram (insert in Figure 2) consists of a weak polycrystalline ring pattern and a strong texture pattern with arc reflections. The latter results from crystals having preferred orientation, which shows that in a given particle most fibrils have a similar orientation.
Scanning Electron Microscope Fractography of a Uranium-7.5 W/O Niobium-2.5 W/O Zirconium Alloy
Authors: Bennett R. K. , Winslow F. R. 
Published: June 2020

A fractographic study of the uranium-7.5 w/o Nb-2.5 w/o Zr alloy was initiated to gain a better understanding of this relatively new material. Although generally a ductile alloy when properly heat treated and aged, brittleness and cracking were encountered in some worked material, and anomalous behavior was observed in a series of double cantilever beam specimens.The original fractographic studies were performed using standard replica techniques in a transmission electron microscope. Shortly after acquisition of a scanning electron microscope, it was found that this instrument was faster, more direct, and supplied more information concerning the overall fracture surfaces of the alloy than the transmission electron microscope.
Dislocation Loops in Zn-0.7% Al Alloy
Authors: Lee E. U. , Kranzlein H. H. 
Published: June 2020

Dislocation loops have been reported mostly in fee metals and alloys after quenching from elevated temperatures and subsequent aging. This paper reports the formation and characteristics of dislocation loops in the hep Zn-0.7% Al alloy resulting from quenching and aging.Zn-0.7% Al sheet specimens, 0.001 inch thick, were quenched from temperatures of 275° to 375°C into iced brine. The aging temperature was -17°C or room temperature. Foil specimens were prepared by electropolishing and examined in a JEM-7 electron microscope.
Particles Seen in Fefeze-Fracture Preparattoks
Authors: Bullivant Stanley 
Published: June 2020

A variety of animal tissues were examined by the simple freeze-fracture technique. An apparatus was used in which the Pt shadowing and carbon coating was carried out through aligned tunnels or apertures. Tn this way the previously fractured cold specimen is protected from contamination.Some particles seen in freeze-fracture replicas can be correlated with structures seen by other electron microscopical techniques. Into this first category fall the broken-off ends of myosin and actin filaments, (Figure 1), the broken-off ends of nucleohistone fibrils the particles seen between membranes in the close junction in cardiac muscle (Figure 2) and quantasomes in chloroplasts. The second group of particles are those found on membranes. An example of these is provided by the membrane faces seen in a fracture through the endoplasmic reticulum (Figure 3). The topology of the situation can be worked out using the outer nuclear membrane as a reference and counting off alternate cytoplasmic and cisternal spaces.
Anchoring Fibrils in Arterial Endothelium
Authors: Trillo A. 
Published: June 2020

There are conflicting reports regarding some fine structural details of arteries from several animal species. Buck denied the existence of a sub-endothelial space, while Karrer and Keech described a space of variable width which separates the endothelium from the underlying internal elastic lamina in aortas of aging rats and mice respectively.The present communication deals with the ultrastrueture of the interface between the endothelial cell layer and the internal elastic lamina as observed in carotid arteries from rabbits of varying ages.
Some Observations on Changes in Denervated Taste Buds of Circumvallate Papillae of Rabbits
Authors: Fujimoto Sunao , Murray Raymond G. , Murray Assia 
Published: June 2020

Taste bud cells in circumvallate papillae of rabbit have been classified into three groups: dark cells; light cells; and type III cells. Unilateral section of the 9th nerve distal to the petrosal ganglion was performed in 18 animals, and changes of each cell type in the denervated buds were observed from 6 hours to 10 days after the operation.Degeneration of nerves is evident at 12 hours (Fig. 1) and by 2 days, nerves are completely lacking in the buds. Invasion by leucocytes into the buds is remarkable from 6 to 12 hours but then decreases. Their extrusion through the pore is seen. Shrinkage and disturbance in arrangement of cells in the buds can be seen at 2 days. Degenerated buds consisting of a few irregular cells and remnants of degenerated cells are present at 4 days, but buds apparently normal except for the loss of nerve elements are still present at 6 days.
Hepatocytes and Renal Proximal Tubules of Bile Fistula Rats
Authors: Hruban Z. , Palmer R. H. 
Published: June 2020

Bile fistulae were produced in adult female Sprague-Dawley rats by cannulation of bile duct. The rats were kept in restraining cages, bile was collected, food and water were given ad libitum and saline was injected s.c. Rats were killed after 26 hrs and three days (60,68,72 hrs).Hepatocytes of rat with 26 hrs bile fistula had markedly dilated rough cisternae. Dilated Golgi sacs contained many moderately dense granules. Homogeneous and heterogeneous dense bodies were small. Lipid droplets were frequent. Hepatocytes of rats with 3 day fistulae (Fig.1) contained many large heterogeneous dense bodies. Golgi sacs and vacuoles were large and contained very dense granules 40 to 85 mμ in diameter (Fig.2).
Stereologic Studies on Hypertrophied Liver Cells of Rats
Authors: Iglesia F.A. De La , Wall C. , Sosa-Lucero J.C. , Lumb G. 
Published: June 2020

Biphenylyl derivatives have been shown to be effective inhibitors of cholesterol biosynthesis. The administration of biphenylyl methylvaleric acid (BMVA), to rats reduces serum and liver cholesterol levels and at the same time induces liver enlargement. This hepatotrophic effect has been confirmed in recent studies, where it was demonstrated that this hepatomegaly was due to an absolute increase of the hepatic mass without changes in the liver cell population, as reflected by the diminished DNA concentration and unchanged total DNA content of the organ.Since this hepatocytic hypertrophy represents an ideal model for studying the process of drug-induced cell enlargement, the present study was aimed to determine the organelles responsible for the liver enlargement by combined light and electron microscopic stereology measurements. Groups of rats were fed 300 mg of BMVA per kg of body weight, mixed with the food.
The Reduction of Chromatic Aberrations Due to Instrumental Instabilities
Authors: Lally J. S. , Evans R. 
Published: June 2020

One of the instrumental factors often limiting the resolution of the electron microscope is image defocussing due to changes in accelerating voltage or objective lens current. This factor is particularly important in high voltage electron microscopes both because of the higher voltages and lens currents required but also because of the inherently longer focal lengths, i.e. 6 mm in contrast to 1.5-2.2 mm for modern short focal length objectives.The usual practice in commercial electron microscopes is to design separately stabilized accelerating voltage and lens supplies. In this case chromatic aberration in the image is caused by the random and independent fluctuations of both the high voltage and objective lens current.
The Elmiskop 51: Features of an Improved Instrument
Authors: Krisch B. , Weichan C. 
Published: June 2020

The 50kV-transmission electronmicro scope ELMISKOP 51 serves as a versatile and efficient device in all laboratories where rapid and easy analysis and comparison of a large number of specimens is demanded. The microscope has been very successfully used in different fields of application as anatomy, pathology, bacteriology and production control (for example, analysis of powder specimens, dye-stuffs, surface replicas of metals and ceramics).On the basis of the well-known electron optical features, i.e. no image rotation and smallest distortion in the whole range of magnification, a second version of the Elmiskop 51 is presented with still more improved reliability and simplicity of operation (Fig. 1). The Elmiskop 51 guarantees now electron microscopic images of the highest possible quality throughout its whole range of magnification: With high resolution photographic material a point-to-point resolution of 20 Å is available.
Electron Irradiation Effects in Polyoxymethylene Crystals Grown Inside Trioxane Crystals
Authors: Colson J. P. , Reneker D. H. 
Published: June 2020

Polyoxymethylene (POM) crystals grow inside trioxane crystals which have been irradiated and heated to a temperature slightly below their melting point. Figure 1 shows a low magnification electron micrograph of a group of such POM crystals. Detailed examination at higher magnification showed that three distinct types of POM crystals grew in a typical sample. The three types of POM crystals were distinguished by the direction that the polymer chain axis in each crystal made with respect to the threefold axis of the trioxane crystal. These polyoxymethylene crystals were described previously.At low magnifications the three types of polymer crystals appeared as slender rods. One type had a hexagonal cross section and the other two types had rectangular cross sections, that is, they were ribbonlike.
Real-Time Infrared Microscanner
Authors: Fisher D. W. , Ordway G. B. , Kaplan H. 
Published: June 2020

An infrared microscanner has been developed which reveals thermal anomalies that indicate surface and internal structural details and should serve as a valuable accessory in the field of microscopy. It already has been used to locate malfunctions in integrated microcircuits, subminiature electronic components, jet engine turbine blades, miniature ball bearings and minute laminated structures. It shows promise for the examination of biological and metallurgical specimens.The instrument combines the features of a radiometric microscope with those of a high sensitivity infrared camera. On its cathode ray tube screen it produces highly magnified thermal images of small objects and small details on larger objects. With its 40X objective it has a field of view 0.064 inch across, a spatial resolution of 0.001 inch, and clearly shows radiation temperature differences smaller than 0.1°C on an object at 30°C. For higher resolution there is a 100X objective that supplies a field of view 0.025 inch across with a spatial resolution of 0.0004 inch.
Minority-Carrier Diffusion Lengths in GaAs Alloys by SEM
Authors: Coutts M. D. , Levin E. R. 
Published: June 2020

Recently SEMS have been used to measure minority-carrier diffusion lengths at semiconductor junctions. In this method the beam scans across the p-n junction and induces a current I.where L is the diffusion length of the minority carriers, Ro the radius of the electron beam; x is the distance from the junction and Io is the current at the junction. In this case L ≫ Ro, and the diffusion length is estimated as the distance from the junction at which the current decays to the fraction 1/e of the maximum value. Previous measurements on GaAs by this method have given values of Ln (the diffusion length in n-type material) from 2-6 μ and of Lp from 2-10 μ. It was also postulated that the dependence of the diffusion length on the accelerating voltage was constant, or saturates at higher accelerating voltages.