bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
The Properties of a Quadrupole Quadruplet Projector
Authors: Kawakatsu H. , Vosburgh K. , Siegel B.
Published: June 2020

The properties of a quadruplet projector have been studied for use in a high resolution electron microscope. The quadruplet consists of four identical quadrupoles each with poles having an inscribed radius, a = 1.5 cm and length 1=3 cm. Fig. 1 shows a typical field distribution and the X-Z and Y-Z ray trajectories for a particular stigmatic setting of the quadruplet which has been built and studied. The first order characteristics of the quadruplet system are shown in Fig. 2.
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.
Observation of Electron Energy Losses in Dark Field Images
Authors: Lally J. S. , Fisher R. M. , Szirmae A. , Hashimoto H.
Published: June 2020

It is commonly assumed that the poor resolution of axially illuminated dark field electron micrographs of crystalline materials is due to the spherical aberration of the objective lens. Actually in many cases the lack of sharpness of the image results from the displacement by chromatic aberration of additional images formed by the electrons which have suffered large energy losses as a result of single or multiple plasmon scattering. In the case of very small diffracting particles, grains or other fine structures in the specimen it is possible to observe multiple images corresponding to these characteristic energy losses. The displacement (Δx) of the image is given by Δx = C f α ΔE/E where C is the chromatic aberration coefficient, f the focal length, α is twice the Bragg angle, E the accelerating potential, and ΔE the energy loss. For a typical plasmon loss of 20 ev the displacement at 100 kv is about 100 Å.
Electronic Read-Out with an Integrating Intensifier System
Authors: Siegel Benjamin M. , Hertel Richard J.
Published: June 2020

Image tube read-out of an electron microscope image must utilize integration of the image, as does photographic recording, if a high signal to noise ratio is to be obtained. The integration time must be of sufficient duration so the noise, or the statistical fluctuations in the number of electrons in an image element is smaller than the signal or contrast of the element with respect to the surrounding region. In our application we are primarily concerned with a system which will allow storage and data processing of the image information contained in the output. An integrating video system can also be used to advantage for visual observation and for focusing, since it provides image intensification at a higher signal to noise ratio than does a conventional intensifier system.
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.
Ion Pumped Vacuum System for the 500 kV University of Virginia Electron
Microscope
Authors: Reisner J. H. , Shapiro S. W. , Lawless K. R.
Published: June 2020

Contemporary microscope design does not lend itself well to ion pumping because of its commitment to the use of many elastomer gaskets with high gas loading. This leads to little change in partial pressure of contaminants and short life of pump elements when ion pumps are merely substituted for oil pumps. With the use of an ion-pumped accelerator on the "Virginia” microscope, and a new column design to minimize gas load, it appeared logical to use an ion pump for the rest of the system. Such a step can only be really successful if the column can be rough-pumped to about 10−4 Torr or better, and if the bulk of the gas load from the photomaterials is not removed by the column ion pump. Prepumping to remove this load is only partially effective if carried on separately from the microscope. Therefore a diffusion pump was added to a conventional type photo loading chamber, so that photomaterials can be introduced directly into the microscope after they have been pumped to pressure of 10−5 − 10−6 Torr which is far below conventional practice.
Alumina Fractured Surfaces as Revealed by Direct Replication Technique
Authors: Gutshall Paul L. , Shaw G. Gordon
Published: June 2020

Electron fractography was used to study the fracture surfaces of double cantilever beam alumina specimens. The desirability of high fidelity direct replication plus the necessity of studying large grain size (10 μ to 45 μ) material led to the following technique. The method described below has yielded results which are superior to the commonly used two-stage replica. The fractured surfaces were 1 mm × 50 mm. The samples were broken into 15 mm lengths and shadowed at 45° from a platinum carbon pellet. A heavy layer of carbon was then deposited normal to the fractured surface and a heavy layer of 5 percent polystyrene in ethylene dichloride was flowed onto the replica. This last layer was allowed to dry 3 hr. at room temperature (this drying time is critical). The specimens were then immersed in concentrated hydrofluoric acid for 15 hr.
Electron Fractographic Analysis of Cemented Carbide Tool Materials
Authors: O'Neill D.
Published: June 2020

A research program is currently being conducted for developing new cemented-carbide tool materials which will be capable of exhibiting exceptional hardness, toughness, strength and oxidation resistance at elevated temperatures. A series of refractory binder alloys in combinaticn with various carbides is being investigated. Liquid phase sintering during the simultaneous application of pressure in a controlled atmosphere hot press is used as the method of densification.
Coherent Interface Contrast in a Nickel Base Alloy
Authors: Oblak J. M. , Kear B. H.
Published: June 2020

During an investigation of recrystallization in the γ′ precipitation hardened nickel-base superalloy Udimet 700 many examples were found of fringe contrast at coherent matrix-γ′ interfaces. The properties of the fringes are those characteristic of so-called “δ-fringes”, as discussed by Gevers et al. A similar phenomenon has been observed in Ni-6.71 wt. % Al, and related to the formation of δ fringes by a tetragonal distortion of the γ matrix at the γ-γ′ interface. The interface fringes in Udimet 700 show surprisingly pronounced contrast despite the small difference in lattice parameter between γ and γ′ (<0.1% vs 0.5% in binary Ni-Al).
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.
Early Scanning Electron Microscopy
Authors: Nixon W.C.
Published: June 2020

The transmission electron microscope can be traced back to the work of K. Knoll and E. Ruska in Berlin who succeeded in 1931 in demonstrating a two lens electron microscope. The scanning electron microscope may also be traced back to the work of M. Knoll in 1935, during a study of secondary electron emission from surfaces. Two cathode ray tubes were used with a time-base generator supplying deflection signals to both tubes at once. The specimen under test was sealed into the first tube and the electron beam from the gun was scanned across the specimen surface and the variations in specimen current formed the signal. This signal was used to modulate the grid of the second cathode ray tube and the image displayed gave the variation in secondary emission on the specimen surface. In one case the word “Stuggart” was shown.
Inexpensive Tape-Recording of Scanning Microscope Images
Authors: Drayton W.B. , Nixon W.C.
Published: June 2020

Dynamic experiments in the scanning electron microscope, as well as other modes of operation, may need continous recording of the information. Cine film gives a permanent record but time is lost in the developing process and as the film is not erasable the cost is high. Video tape recording as used in television broadcasting is possible in principle but is even more expensive in terms of initial capital cost. The slower frame rates used in the scanning electron microscope permit the use of audio tape recorders with a bandwidth of less than 20 kHz provided, that some further modifications are made.
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.
Visualization of Internal Skin Structures with the Scanning Electron Microscope
Authors: Bernstein Emil
Published: June 2020

An interesting method for examining structures in g. pig skin has been developed. By modifying an existing technique for splitting skin into its two main components—epidermis and dermis—we can in effect create new surfaces which can be examined with the scanning electron microscope (SEM). Although this method is not offered as a complete substitute for sectioning, it provides the investigator with a means for examining certain structures such as hair follicles and glands intact. The great depth of field of the SEM complements the technique so that a very “realistic” picture of the organ is obtained.
Deformation Structures in Quartz Rocks
Authors: Tighe N. J. , Christie J. M.
Published: June 2020

Plastic deformation of quartz has been produced experimentally under high confining pressures and crushed fragments of such samples have been observed in the electron microscope. In order to relate experimentally produced plastic deformation to that occurring in quartz aggregates or rocks, it is desirable to have samples taken from standard petrographic thin sections so that deformation textures can be observed optically and then areas selected for electron microscopic observation. In the present study, such specimens were made from sections of quartzite, mylonite and flint rocks and from an experimentally deformed single crystal specimen of quartz.
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.
A Combined Conventional and Scanning Electron Microscope
Authors: Ong P.S.
Published: June 2020

In electron optical instrumentation, it would be generally desirable to have a lens with a short focal length. Both spherical and chromatical aberration decreases with focal length and this will result in a better resolution and image brightness. This consideration has been taken into account in the design of conventional electron microscopes, and the focal length of the objective lens of such instrumentation ranges from a few millimeters to a fraction of a millimeter. A short focal length lens requires that the specimen be located in a magnetic field i.e., within the pole piece gap. This results in (a) a limitation in the size of the specimen and (b) a restriction, to use the microscope to nonmagnetic specimens only.
Black-and-White and Color Image-Tone Enhancement in Scanning Electron Microscopy
Authors: Rossi Franco
Published: June 2020

In scanning electron microscopy, the specimen surface is scanned with a very fine electron beam, and the emitted secondary electrons are used to control the intensity of a synchronized writing beam scanning the screen of a viewing tube. The resulting image is recorded photographically by using conventional optical systems. The brightness of the image elements depends on their secondary electron yield and the amplification factor. The secondary electron yield itself depends on the surface material, the angle of incidence, and the velocity of the primary beam.
Microtoming Clay Coated Paper
Authors: Marsh Peter A. , Price Dale , Mullens Troy J.
Published: June 2020

One of the problems associated with the coating of papers is the relating of pigment packing in the coated film to the properties of the coated paper. Electron microscopy of paper cross-sections appeared to be the most promising approach to characterize particle packing. Our original attempts to cross-section coated papers resulted in varying degrees of distortion of the pigment particles, separating of the coating from the paper, and a splitting of the clay coating from the embedding media. This paper describes a cross-sectioning technique that minimizes these problems.
Magnetic Stirring During Electrolytic Thinning
Authors: Dash J. , Roeter R.W. , King W.W.
Published: June 2020

The profile of an electrolytically-thinned metal foil is largely determined by the combined effects of electric and gravitational fields. Uniform thinning can be approached by making the applied electric field as uniform as possible and by utilizing some kind of stirring to counteract the variation in viscous anode layer thickness caused by gravity. Gas evolution at the sample may also play an important role in the process. Because of the ionic nature of electrolysis, it might be expected that applied magnetic fields of appreciable strength should produce significant changes in the process due to the Lorentz force on charged particles. Preliminary experiments have shown that this is the case. The net effect of these changes in the experiments thus far has been to enhance the uniformity of thinning.
Voids in Irradiated Tungsten and Molybdenum
Authors: Rau Robert C. , Ladd Robert L.
Published: June 2020

Recent studies have shown the presence of voids in several face-centered cubic metals after neutron irradiation at elevated temperatures. These voids were found when the irradiation temperature was above 0.3 Tm where Tm is the absolute melting point, and were ascribed to the agglomeration of lattice vacancies resulting from fast neutron generated displacement cascades. The present paper reports the existence of similar voids in the body-centered cubic metals tungsten and molybdenum.
Direct Observation of Deformation Microstructures Surrounding a Bullet Hole in Stainless Steel Sheet
Authors: Murr L. E. , Foltz J. V.
Published: June 2020

Analytical treatments of high-velocity penetration and perforation of thin sheet materials invariably invoke numerous assumptions concerning the work-hardening qualities of the material, and the range and character of the residual deformation. However, with the inherent capability of transmission electron microscopy to accurately reveal the nature and extent of residual defect substructures associated with ballistic perforation, it is readily observed that a powerful-direct approach exists for the analysis of such related problems.
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.
Mechano- and Chemo-Receptors in the Antenna of Tenebrio Molitor in the Larval Stage
Authors: Pierantoni R. L.
Published: June 2020

Recent studies on learning and transfer of memory through the metamorphosis in Tenebrio molitor have emphasized the need for detailed information concerning sensory structures. In the course of a more complete structural study of the Tenebrio sensory system the antenna has been investigated with light microscopy and scanning and transmission electron microscopy. The antenna is composed of three segments interconnected by flexible “bellows” which provide each element with a certain degree of freedom.
Initiation of Shell Formation in the Bivalve, Mytilus Epulis
Authors: Humphreys Walter J.
Published: June 2020

Within 24 hours after fertilization of the egg of Mytilus edulis a few mid-dorsal ectodermal cells of the resulting trochophore differentiate into a shell gland that is already secreting a shell (s, Figs. 1-3). By 70 hours the shell gland and the shell secreted by it grows to enclose most of the embryo. Formation of this larval shell (actually a thin pellicle that becomes the periostrocum) involves at least two steps: 1) the formation of a thin pellicle above the secreting surface of the cells, and 2) a thickening of the pellicle by deposition of Golgi-derived secretory products onto its inner surface.
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.
Selective Staining of Cortical Granules and Golgi Cisternae inArbacia Punctulata
Authors: Bal Arya K. , Cousineau Gilles H.
Published: June 2020

Cyto-chemical staining techniques at the light microscope level have revealed the presence of mucopolysaccharides and proteins in the cortical granules of Eichinoderm eggs. In routine electron microscopy preparation the cortical granules appear to have two morphologically distinct components - an electron dense inner component (dark bodies) surrounded by a less-electron dense material. In the present investigation it has been made possible to stain the dense inner material selectively with Phosphotungstic acid (PTA) in non-osmicated aldehyde fixed oocytes and eggs ofArbacia punctulata.
Synaptic and Extra-Synaptic Intercellular Filaments in Brain Cortex
Authors: Carlo Vincenzo Di
Published: June 2020

In the course of high-resolution electron microscopical investigations on the morphology and distribution of RNA-containing organelles in the neuropil of mammalian brain cortex, thin filaments were observed bridging the intercellular gap between non-synaptic areas of neuronal processes as well as between neuronal processes and glial cells. Some among them are over 200 mμ long. Morphologically these intercellular filaments are quite similar to the filaments which, inside polysomes, connect one ribosome to the others and which other investigators interpreted as being messenger-RNA. As a matter of fact, the intercellular filaments are often closely associated with dense bodies which can be identified as ribosomes (Fig. 2 and 3). Some of the filaments, however, appear to be only a few hundred A long and appear not to contact ribosomes. On the other hand, at present one cannot exclude that these apparently short filaments may actually be longer and be connected with ribosomes in areas outside the focal plane of the electron micrographs or even outside the very thin section of tissue under observation.
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.
Current Concepts of the Molecular Architecture of Unit Membranes
Authors: Robertson J. David
Published: June 2020

The unit membrane theory is based mainly on biophysical studies of nerve myelin. It deals only with general molecular architectural principles. It states that the core of the membrane is comprised of a lipid bilayer with the polar heads directed outward, and that these are associated with monolayers of non-lipid (mostly protein) which are chemically different from one another. The theory does not deal with the identification of or bonding between components, makes no specification about conformational states of the protein and does not exclude that some projections of the non-lipid molecules may penetrate somewhat into the lipid bilayer. It does say, however, that any such penetration does not cross the membrane core completely at small regular spacings.
Ultrastructural Changes in the Ependyma of the Septum Pellucidum in Acute Experimental Hydrocephalus in the Rhesus Monkey
Authors: McGrath Philip P. , Clark Ronald G. , Milhorat Thomas H. , Ewell John B.
Published: June 2020

Intercellular spaces separate ependymal cells from one another except where they are united by cellular junctions. Two types of gap junctions exist between these cells. It had been previously thought that one of these was a true tight junction, but recently it has been shown to be a seven layered gap junction. The stability of epithelial junctions under stress in tissues other than brain is well documented. Light microscopic studies currently in progress have indicated that the ependyma of the septum pellucidum becomes severely stretched within a matter of hours following experimental obstruction of the 4th ventricle by a technique described by Milhorat. It was therefore decided to investigate this area with the electron microscope in order to study the junctions under such severe stress.
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).
Myocardial Alterations in Cats Kept at 14,110 Feet Elevation for Three Months
Authors: Bischoff M. B. , Dean W. D. , Bucci T. J.
Published: June 2020

Right ventricular hypertrophy occurs in several animal species when transported from sea level to high altitude. Previous electron microscopic studies in our laboratory have shown enlargement of mitochondria with degeneration of cristae, separation of myofibrils, and increased accumulations of lipid and particulate glycogen in myocardial cells of dogs, rabbits and rats maintained at high altitude for five months. Edematous endothelial cells of the myocardial capillaries were also observed. Our recent work showed that adult cats native to 5,380 feet subjected to 14, 110 feet elevation for 90 days also developed cardiac hypertrophy. The cardiac tissue was examined by light and electron microscopy and the results comprise this communication.
Infection of Escherichia coli with bacteriophages
Authors: Bayer Manfred E.
Published: June 2020

The first step in the infection of a bacterium by a virus consists of a collision between cell and bacteriophage. The presence of virus-specific receptors on the cell surface will trigger a number of events leading eventually to release of the phage nucleic acid. The execution of the various "steps" in the infection process varies from one virus-type to the other, depending on the anatomy of the virus. Small viruses like ØX 174 and MS2 adsorb directly with their capsid to the bacterial receptors, while other phages possess attachment organelles of varying complexity. In bacteriophages T3 (Fig. 1) and T7 the small conical processes of their heads point toward the adsorption site; a welldefined baseplate is attached to the head of P22; heads without baseplates are not infective.
Freeze-Etching of Malarial Parasites
Authors: Ladda Roger L. , Steere Russell L.
Published: June 2020

The freeze-etching technique introduced by Steere permits the rapid preparation of replicas of biological specimens for ultrastructural study without subjecting the specimens to drastic procedures of long fixation, dehydration and embedding. Fresh cells or cells briefly exposed to glutaraldehyde are frozen in 40% glycerol at -190°C and fractured under vacuum. A carbon-platinum replica is made of the exposed surfaces. The replica is washed free of adherent specimen with chromic acid and clean distilled water, mounted on a collodion coated grid and is ready for study. The resulting cleavage planes not only provide cross-sectional views of the cells, but frequently both the cell limiting and intracellular membrane surfaces are exposed providing a 3-dimensional view of structure. The technique is particularly useful in the study of intracellular parasites, such as the malarial parasite, which can not be easily isolated from host cell membranes without severe morphological alterations to the parasite.
The Degradation of the Rhinovirion as Studied By High Resolution Stereo Electron Microscopy
Authors: Reeves Jerry D. , Mayor Heather D.
Published: June 2020

Picornaviruses, a group of small RNA-containing viruses are further divided into two sub-groups, the enteroviruses which are acid stable, and the rhinoviruses which suffer marked loss of infectivity at acid pH. We have found a ninety per cent decrease in infectious titer after subjection to pH 5.5 as compared to the titer of the original material at pH 7. 0. Considerable morphological degradation of the virion, as monitored by electron microscopy, has also occurred by pH 5. 5. It appears that capsid breakdown proceeds through loss of a vertex capsomere group followed by release of the viral genome in the form of a ribonucleoprotein strand (Fig. 1). However, the conventional flattened electron microscopic image produced by these small virus particles makes further interpretation at a high resolution extremely difficult.
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 High Resolution Appearance of Biological Substrates
Authors: Haydon Glen B.
Published: June 2020

High resolution electron microscopic study of negatively stained macromolecules and thin sections of tissue embedded in a variety of media are difficult to interpret because of the superimposed phase image granularity. Although all of the information concerning the biological structure of interest may be present in a defocused electron micrograph, the high contrast of large phase image granules produced by the substrate makes it impossible to distinguish the phase ‘points’ from discrete structures of the same dimensions. Theory predicts the findings; however, it does not allow an appreciation of the actual appearance of the image under various conditions. Therefore, though perhaps trivial, training of the cheapest computer produced by mass labor has been undertaken in order to learn to appreciate the factors which affect the appearance of the background in high resolution electron micrographs.
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.
Effect of Inter-Particle Sintering on the Microstructure of γ Fe2O3
Authors: Olsen K. H. , Cox J. W.
Published: June 2020

The use of γ Fe2O3 as a magnetic recording pigment is well known. Most commonly it is prepared by dehydration of the ∝ FeOOH to ∝ Fe2O3, reduction of ∝ Fe2O3 in hydrogen or other reducing gas to Fe3O4 and finally oxidation of the Fe3O4 to γ Fe2O3.

Because of the known influence of grain boundaries on magnetic domains, a knowledge of the microstructure of the individual magnetic particles is important in theoretical considerations of switching mechanisms. Literature references disagree on the microstructure of γ Fe2O3. Some investigators claim the individual particles are essentially single crystalline ; others claim the particles are polycrystalline. In the present work, we have found no evidence that sub-grains are nucleated during the structural transformations of ∝ Fe2O3 to γ Fe2O3. Rather we have found that the single crystalline character of the starting ∝ FeOOH is preserved through the conversion to γ Fe2O3.
Domain Formation in Synthetic Quartz
Authors: Comer Joseph J.
Published: June 2020

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.
Computer Prediction of Many-Beam Kikuchi Patterns
Authors: Thomas L. E.
Published: June 2020

Kikuchi diffraction patterns provide valuable information about the diffraction contrast images observed in TEM of crystals. For example, the “critical voltage” phenomenon of vanishing 2nd order Bragg reflection and the marked changes in transmission and contrast behavior above 100 kv due to increased many-beam systematic interactions are reflected in the K-patterns. New developments on a method for predicting both conventional (2-beam) and many-beam K-patterns and on CRT image simulation of the results will be discussed.

Kikuchi patterns are formed by diffraction of electrons that have been diffused within the crystal by inelastic scattering from a parallel incident beam. For simplicity, however, we consider diffraction from a diffuse incident beam of appropriate angular distribution and use the reciprocity theorem of optics to relate the intensities in diffuse-beam diffraction to those in parallel beam diffraction. This allows the K-patterns to be calculated from many-beam dynamical theory of diffraction including absorption developed for TEM.
Electrolytic Breakdown of Anodic Films on Aluminum
Authors: Zahavi J. , Metzger M.
Published: June 2020

Electron microscopy has been used for some time in studying topography and structure of anodic films for identification and measurement of cell and pore structures and for detection of flaws or of various forms of breakdown, but usually at high forming voltages yielding relatively large scale features. For film formation with accompanying dissolution, leading to films of the porous type, the structure at cell voltages of several volts and below is of interest in regard to formation and dissolution mechanisms in general and to the stability and breakdown of corrosion films, in particular. As a first step, we have studied the films on aluminum, of known purity and microstructure, electropolished in a perchloric acid-ethanol bath and formed in 2.4 M sulfuric acid at a relatively low constant current density of 5 ma/cm2 giving steady state conditions of slow film growth at relatively low current efficiency.
UHV RHEED and Replica Studies of NaCl Films Formed on Mica
Authors: Koch F. A. , Vook R. W.
Published: June 2020

Thick (1500 to 2500 A) NaCl films were formed under ultra high vacuum (UHV) conditions on aircleaved mica substrates at 25, 100, 150, 200, 250, 300 and 380°C by vacuum deposition. A modified version of a UHV reflection high energy electron diffraction (RHEED) camera, designed and constructed in our laboratory was used for these studies. Typical residual gas pressures after bakeout were in the low 10-10 torr range. The aircleaved muscovite mica substrate was clamped to an OFHC copper block about 10 cm. from the resistance heated vapor source. The substrate was outgassed in UHV at 400 C for a period of at least 12 hours before cooling to the deposition temperature. During deposition the pressure was kept in the 10-9 torr range. The film was examined first in situ by the UHV RHEED technique and then replicated. Finally the system was opened and the Ge-SiO replicas mounted on Cu grids and examined by transmission electron microscopy.
Effect of Temperature on Ectotherm Tissue Ultrastructure
Authors: Giaquinta Robert , MacMahon James A.
Published: June 2020

Environmental temperature variations result in physiological compensations in the metabolism of ectotherms. These compensatory mechanisms are manifested at various organizational levels within the organism. Compensatory changes at the cellular level constitute the most fundamental mechanisms involved during the acclimation process. The metabolism of various tissues during temperature acclimation has been the subject of numerous investigations (Prosser, 1967). Hochachka (1967) demonstrated increased activities of various metabolic pathways including the pentose shunt, lipogenesis and glycogenesis during cold temperature compensation. Limited information is available concerning the ultrastructure correlates of tissues in response to temperature variations and temperature extremes. This paper reports some preliminary results concerning the effect of temperature on the ultrastructure of various tissues of ectotherms.

Heart, liver, skeletal muscle, and brain tissue were excised from heat killed sidewinders, Crotalus cerastes, as were tissues from C. cerastes acclimated to 20 and 30 C. Prefixation was carried out in 3%, cacodylate buffered glutaraldehyde followed by postfixation in 1%, osmium tetroxide. Acetone dehydration and epon embedment were according to standard procedure.
Ultrastructure and Staining of Developing Elastic Tissue
Authors: Albert E. N.
Published: June 2020

Silver tetraphenylporphine sulfonate (Ag-TPPS) was synthesized in this laboratory and used as an electron dense stain for elastic tissue (Fig 1). The procedures for the synthesis of tetraphenylporphine sulfonate and the staining method for mature elastic tissue have been described previously.

The fine structure of developing elastic tissue was observed in fetal and new born rat aorta using tetraphenylporphine sulfonate, phosphotungstic acid, uranyl acetate and lead citrate. The newly forming elastica consisted of two morphologically distinct components. These were a central amorphous and a peripheral fibrous. The ratio of the central amorphous and the peripheral fibrillar portion changed in favor of the former with increasing age.

It was also observed that the staining properties of the two components were entirely different. The peripheral fibrous component stained with uranyl acetate and/or lead citrate while the central amorphous portion demonstrated no affinity for these stains. On the other hand, the central amorphous portion of developing elastic fibers stained vigorously with silver tetraphenylporphine sulfonate, while the fibrillar part did not (compare figs 2, 3, 4). Based upon the above observations it is proposed that developing elastica consists of two components that are morphologically and chemically different.