bluuebunny/crossref_metadata_2025_split huggingface dataset:
Energy Dispersion X-ray Analysis: Absorption and Background Effects Observed in the TEM
Authors: Duff R. H. , Bender S. L. 
Published: June 2020

The need to obtain quantitative data from an energy dispersive X-ray spectrometer following its successful adaptation to a transmission electron microscope requires a knowledge of the absorption properties of X-rays in thin films in order to utilize the X-ray intensities generated and to select an optinum excitation potential. Information relating specimen thickness and accelerating potential to signal intensity for pure substances is necessary before analyses of more complicated systems with varying thicknesses can be undertaken.For this purpose, gold films of varying thickness (measured by using the Fizeau fringes in an interference microscope) were thermally evaporated onto freshly cleaved rock salt substrates, floated off on water and picked up on nickel grids.
Techniques for Examining Void Distribution in Ion Bombarded Metals
Authors: Wolff U. E. , Lauritzen T. , Rosenbaum H. S. 
Published: June 2020

Ion bombardment is a convenient and economical means for simulating the damage produced in metals due to fast neutron irradiation. Unlike that produced by neutrons, however, the damage caused by ion bombardment is not homogeneously distributed throughout the volume of the metal since ions penetrate metallic specimens only a short distance. Moreover, the number of displaced atoms is a sensitive function of the kinetic energy of the bombarding ions as well as the depth within the target material (specimen). Therefore materials which have been subjected to ion bombardment require careful analysis of the spatial distribution of the damage before meaningful inferences can be made.The experimental material for this study was Type-304 stainless steel sheet, approximately 100 μm thick, which was bombarded in a cyclotron with 12 MeV deuterons. Irradiation time and temperature were the principal variables. Because of the small size of the voids produced and the shallow damage zone, techniques of transmission electron microscopy (TEM) are most commonly used for void examination. In the present work we compare two alternative approaches to the problem of characterizing the spatial distribution of damage within such specimens.
Reconstruction of Three Dimensional Structures from Electron Micrographs: The Equivalence of Two Methods
Authors: Lake James A. 
Published: June 2020

A transmission electron micrograph is to a good degree of approximation a projection of a three dimensional structure. Provided that a sufficient number of projections are available, it is possible to reconstruct a three dimensional structure which is consistent with the projections. Among the methods which have been proposed for generating a three dimensional structure from projections, two methods alone produce single, unique structures which are consistent, in a least squares sense, with the projections from which they are derived.The first of these was demonstrated by DeRosier and Klug in a reconstruction of the tail of the bacteriophage T4. Their technique is illustrated in figure 1. A three dimensional structure, represented by the duck, is Fourier transformed to yield a three dimensional Fourier transform. (Fourier transformation is a mathematical operation readily performed on a digital computer.) An inverse Fourier transformation exists and the Fourier transform of the duck may be inversely transformed to recreate the three dimensional duck structure.
The Formation of Crystallographically Aligned a/3 <112> Dislocations in Ni3Al
Authors: Giamei A. F. , Oblak J. M. , Kear B. H. , Rand W. H. 
Published: June 2020

Although intrinsic stacking faults have been observed in cold rolled polycrystalline Ni3Al, the terminating superlattice partial dislocations have not been identified. Since superlattice intrinsic stacking faults (S-ISF) can be formed by the glide of a/3 <112> partials, we have recently suggested specific interactions between paired a/2 <110> slip dislocations which could result in the formation of such partials. In the present study the partial dislocations and associated stacking faults formed during multiple slip in Ni3Al are identified. These partials have a/3 <112> Burgers vectors and lie parallel to <110> directions. The latter is explained in terms of the relaxation of the superlattice partials along cube planes.Thin foils were prepared from sheets of directionally solidified columnar-grained Ni3Al that had been rolled (~ 5% reduction) along the common <100> direction. While the familiar long straight a/2 <110> type screw dislocation pairs were observed in some grains, extended stacking faults were present in most areas of the foil where multiple slip had occurred, Figure 1.
S.E.M.-T.E.M. Image Comparison
Authors: Greene G. M. , Sprys J. W. 
Published: June 2020

The present study demonstrates that fracture surfaces appear strikingly different when observed in the transmission electron microscope by replication and in the scanning electron microscope by backscattering and secondary emission. It is important to know what form these differences take because of the limitations of each instrument. Replication is useful for study of surfaces too large for insertion into the S.E.M. and for resolution of fine detail at high magnification with the T.E.M. Scanning microscopy reduces sample preparation time and allows large sections of the actual surface to be viewed.In the present investigation various modes of the S.E.M. along with the transmission mode in the T.E.M. were used to study one area of a fatigue surface of a low carbon steel. Following transmission study of a platinum carbon replica in the T.E.M. and S.E.M. the replica was coated with a gold layer approximately 200A° in thickness to improve electron emission.
Examination of Surveyor III Moonlander Support Strut by TEM
Authors: Buvinger E. A. 
Published: June 2020

The Surveyor III spacecraft was landed on the lunar surface in the Ocean of Storms on April 20, 1967. Thirty-one months later the crew of Apollo 12 removed several items of interest from the moonlander and returned them to Earth. Among these was a length of polished, unpainted aluminum tubing which had been part of the support strut for the Radar Altitude Doppler Velocity Sensor (RADVS). At the Lunar Receiving Laboratory the tubing was cut into sections for study by various investigators. Two sections (C and E) were examined by the author to determine the type and degree of microscopic damage which the tubing had incurred during its exposure to the lunar environment. Specifically, the surface was examined for evidence of ion bombardment by solar wind and for micro-meteorite impact damage.Replication electron microscopy was used to perform the study. The replicating plastic was elvanol (polyvinyl alcohol), and the replicas were shadowed at 10 or 25 degrees with Pt-C.
Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy
Authors: Low N. M. P. , Brosselard L. E. 
Published: June 2020

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.
Electron Microscopy of Porous Materials—The Structure of a Commercial Alumina Catalyst Support
Authors: Faulkner D. , Sagert N. H. , Sexton E. E. , Styles R. C. 
Published: June 2020

Many practical catalysts consist of a metal supported on a stable material. The activity of such a system depends not only on the chemical properties of the metal and support, but also on certain physical properties of the support such as surface area, pore volume and pore size distribution. Indirect information on the pore structure of the support material can be obtained from low-temperature nitrogen adsorption experiments, but a more direct technique for obtaining this information is to examine the material in the electron microscope.The material chosen for this study was a high porosity alumina obtained from Englehard. The pore size distribution as supplied by the manufacturer indicated 0.24 cc of pores/g in the range 0-100Å, and 0.16 cc/g > 100Å. Figure 1 is a scanning electron micrograph of the surface of the material. Although no great detail can be resolved, the surface is obviously uneven, and gives the impression of being somewhat fibrous in texture. Figure 2 is a transmission electron micrograph of the same material. This sample was prepared by crushing the material and dispersing the particles on a carbon substrate.
Electron Microscopic Evidence of Authigcnic Clay Minerals in the Gulf of Mexico
Authors: McKce Thomas R. , Whitehouse U. Grant 
Published: June 2020

Authigenic mineral formation is one consequence of the geochemlcal model of a steady-state ocean-atmosphere. Many examples of authigenic clay minerals might be expected, however the distinction between authigenic and detritial clay minerals is not well defined. It is extremely difficult in most cases to distinguish between the two while running a standard mineraloglcal analysis. Consequently the formation or reconstitutlon of clay minerals in the world oceans has remained a matter of much consideration.Weaver points out that many of the clay minerals occuring in recent marine environments which are identified as being definitely authigenic are Fe-rich. These include glauconlte, nontronite, chamosite, montmorillonite and chlorite. The majority of these have been found in the Pacific Ocean with montmorillonite being the most abundant. Norin reported authigenic illitic mica in coarse-grained sediments from the Tyrrhenian Sea. Garrels has compiled a phase diagram which indicates that under the conditions normally found in seawater, kaolinite and K-mica can exist in mutual equilibrium growing from a solution derived from K-feldspar and quartz.
Fatigue Properties of Clad Metals
Authors: Turk C. , Santala T. , Jean D. 
Published: June 2020

Theoretical and experimental investigations have shown that a propagating crack can interact with an internal interface significantly affecting the bulk properties of the composite. Because only limited work has been reported regarding the effect of a laminate structure on fatigue life, Texas Instruments Conflex 326 material, which consists of 10 volume-%. OFHC copper metallurgically bonded on both sides of 80 volume-% AISI 1065 steel, was selected for fatigue experiments to study the behavior of the crack at the interface.All laminates were roll bonded, reduced to gage and annealed at 1375°F for one hour. Monolithic steel was obtained for testing by dissolving the copper cladding in a concentrated nitric acid. Milled fatigue and tensile specimens were austenitized for one hour at 1500-1550°F and water quenched. Tempering specimens were tempered at temperatures from 200°F to 1100°F. Figure 1 shows the microstructure of the core material for samples tempered at 200°F, 600°F, and 1000°F.
Ultrastructure of Aspergillus Fumigatus Spores: Conidiation and Maturation
Authors: Ghiorse William C. , Edwards Mercedes R. 
Published: June 2020

Ultrastructural aspects of developing conidia and phialides of fungi have been investigated. The present report deals with an electron microscope study of developing and maturing conidia in A. fumigatus.The strain selected sporulated profusely on potato dextrose agar at 37 C. Observations on conidiation and on immature spores were carried out on 24 or 48 hr cultures. Aerial conidiophores were fixed in situ by flooding the culture with cacodylate buffered glutaraldehyde containing 0.01 M calcium chloride and 0.3% Tween 80. Fixation proceeded under vacuum, at it C, overnight. Portions of mycelium were selected under a dissecting microscope while being washed in buffer. Osmication, dehydration, and embedding in Epon were by standard procedures, except for a prolonged infiltration time. For observations on mature conidia, 2 to 21 day cultures were used. Spores were washed from the surface of the agar with the fixative solution and collected by centrifugation. Fixation continued in a manner similar to that used for the aerial conidiophores.
Comparison of Normal and Cystic Fibrotic Skin Fibroblasts
Authors: Korinek Josef , Robinson John P. 
Published: June 2020

We have recently examined skin fibroblasts grown in tissue culture from five normal, three CF and two heterozygous individuals. The cell lines used in these experiments had been subcultured between one and ten times. Our ultrastructural observation as well as results of metachromatic staining with toluidine blue O essentially agree with those reported by Bartman et al.Although the membranous bodies in CF cells appear to be lysosomes, to our knowledge no histochemical examination of these granules for the presence of lysosomal enzymes has been reported in skin fibroblasts from CF individuals. We examined these bodies for the presence of acid phosphatase in normal, heterozygous and homozygous skin fibroblasts. Our results indicate that the cytoplasmic granules which produce metachromatic staining with toluidine blue O were of about the same size as those structures revealing the presence of acid phosphatase in electron micrographs.
Electron Microscopic Observations of Purified Oat Phytochrome
Authors: Stasny J. T. , Mumford F. E. 
Published: June 2020

The following describes the gross morphology of purified oat phytochrome, as examined by negative staining for electron microscopy. Phytochrome, a chromoprotein important in plant photomorphogenesis, has two photoconvertible forms: PR, absorbing maximally at 664 nm and PFR at 724 nm. Although the isolation and purification of this photoreceptor has been achieved in several laboratories, its molecular dimensions have not been adequately characterized.Phytochrome was extracted from etiolated oat seedlings and purified by a previously published method. The purified oat phytochrome was prepared for electron microscopic examination by precipitation at 50 percent saturation with ammonium sulphate, followed by centrifugation at 30,000xg for 20 minutes. The resulting pellet was dissolved in twice-distilled water to give a protein concentration of approximately 200 ug/ml and then dialyzed against 1000X its volume of distilled water for 18 hours at 4°C.
(EB) Virus: Latency and Expression in Transplanted and Cultured Human Cells
Authors: Uzman B. G. , Kasac M. M. , Saito H. , Krishan A. 
Published: June 2020

In conjunction with the cultivation and transplantation of cells from human tumors by the Programs of Microbiology and Immunogenetics, virus surveillance by electron microscopy has been routinely employed. Of particular interest in this regard have been 3 cell lines cultured from lymph nodes or spleen of 2 patients with Hodgkin's disease and 1 patient with Letterer-Siwe's disease. Each of these cell lines when transplanted in Syrian hamster neonates conditioned with anti-lymphocyte serum grew as serially transplantable tumors; from such transplants of the 3 cell lines cell cultures were retrieved.Herpes type virus particles (Figs. 1, 2, 3) were found in the primary cultures of all three lines, in frozen thawed aliquots of same, and in cultures retrieved from their tumors growing by serial transplantation in hamsters. No virus was detected in sections of 25 of the serially transplanted tumors. However, in 10 such tumors there were repeated instances of tubular arrays in the cisternae of the endoplasmic reticulum (Fig. 4). On serologic examination the herpes virus was shown to be the Epstein-Barr virus.
Specialized Epithelia in the Avian Labyrinth (Its Distribution and Ultrastructure)
Authors: Ishiyama E. , Weibel J. , Myers E. N. 
Published: June 2020

In recently years the distribution of the non-sensory specialized epithella in the inner ear has been interested among otologists. Increased understanding of the problem dealing with the fluid transport within the endolymph has been obtained these studied. To our knowledge, however, the distribution of the avian specialized cells in the inner ear has not been described adequately. In addition, ultrastructural characteristics of the osmiophilic(dark) cells in the avian labyrinth were not clearly demonstrated. Therefore, the specialized epithlia in the avian labyrinth should be further investigated and the nature of their function defined.To demonstrat this, pigeois were investigated using phase and electron-microscopy. The specialized cells(dark and light cells) were distributed in the crlstae ampullaris, the tegmentum vasculosum of the lagena which is analogous to the stria vascularis in mammals, the saccule, the otolith lagena, the utricle and the crista negletica.
Ultrastructure of the Schistosome Granuloma
Authors: Mount P. M. 
Published: June 2020

Adults of the digenetic trematode Schistosoma mansoni inhabit the mesenteric veins of their definitive hosts. A wide variety of mammals ranging from mice to men are susceptible to infection. Little or no pathology is associated with the adults' presence within the blood vessels. However, the majority of the eggs laid by the adults fail to pass from the host, are carried in the veins to the liver or intestinal wall, and become trapped in the tissues where they elicit a granulomatous response.The schistosome granuloma has been found to be a manifestation of delayed hypersensitivity and as such represents an immunologically specific inflammatory response to the presence of e'ggs. Thus, this type of granuloma can be distinguished from the immunologically non-specific type of granulomas that occur around inert foreign bodies when they become trapped in tissue. It has been hypothesized that granuloma formation represents an attempt by the host to sequester and destroy antigens of low diffusibility which are released from the egg. This report describes some preliminary observations on the ultrastructure of granulomas elicited by Schistosoma mansoni eggs in the liver of experimentally infected white mice.
The External Shape of Human γ GI Immunoglobulin from Crystal Sections
Authors: Labaw L. W. 
Published: June 2020

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.
Experimental Approach to the Structural Water of Fibrin Molecules. —A Test for Electron Microscopic Models
Authors: Köppel G. , Vacca J. G. 
Published: June 2020

Clots of bovine fibrinogen and test thrombin (Behringwerke) were standardized with respect to dry weight and dimensions, placed in a modified Millipore Filter System, exposed to a continuous air stream of high humidity and thus subjected to a slow drying process. The clots collapsed in a symmetrical manner, and their heights were reduced from approximately 8 mm at zero hour to 180-230/μm after 5 hours and to 50/μm after 12 hours of drying. The heights of the collapsed clots were measured after dehydration and embedding in Epon 812.The water content of the clots after various times of drying was determined from the difference of their wet weights and their dry weights which were taken after heat drying at 105°C. If the water content is plotted versus time of drying, a biphasic drying curve results showing the presence of three phases: 1) during the first 3½ hours of the experiment water evaporates at a fast rate, 2) then the curve levels at a water content of approximately 84% water by weight.
Scanning Electron Microscopy of the Red Pulp of the Spleen
Authors: Miyoshi Masayuki 
Published: June 2020

In spite of various attempts, conclusive evidence to explain blood passage in the splenic red pulp does not seem to have been presented. Scanning electron microscope (SEM) observations on the rabbit spleen, originally performed by us, revealed that the sinus was lined by a perforated lattice composed of longitudinally extended rod cells and transverse cytoplasmic processes, and that perforations in the lattice were continuous to the spaces among the stellate reticulum cells of the cord. In the present study the observation was extended to the dog and rat spleens, in which the cord is more developed than in the rabbit in order to clarify the possible differences in the fine structure of the sinus wall. An attempt was also made to examine the development and distribution of macrophage in the blood passage of the red pulp.Spleens were washed and fixed by perfusion with Ringer solution and then with buffered glutaraldehyde. Small tissue cubes were dehydrated with acetone, dried in air and heated with gold. Observations were made by a JEOL SEM Type-3. One air dried tissue cube was cut into small pieces and post fixed with buffered OsO4 for examination under the transmission electron microscope (TEM).
A Unique Cell Contact in the Adrenal Cortex
Authors: Friend Daniel S. 
Published: June 2020

A unique periodic structure exists between cortical cells in all zones of the mature rat, guinea pig, and human adrenal gland. This singular zonule is most highly developed between the lateral cell surfaces and between the basilar, perisinusoidal, interdigitating microvilli in the zona fasciculata and occasionally occurs between microvilli of the same cell. In the rat, its fine structure is not appreciably altered by hypophysectomy or adrenocorticotrophic hormone stimulation.In views which crisply reveal the unit membrane architecture of the smoothly parallel plasma membranes, the 250-350-Å intercellular space is bisected by a series of circles 80-150 Å in diameter varying widely in center-to-center spacing (160-400 Å). This area of contact resembles the zonula continua in its appearance after aldehyde, OsO4, and aldehyde-OsO4-phosphotungstic acid fixation and in its facile digestibility by protease in Epon sections.