bluuebunny/crossref_metadata_2025_split huggingface dataset:
Osbservations on the Cysts of Entamoeba Histolytica
Authors: Miller J. H. , Deas J. E. 
Published: June 2020

Trophozoites of the Laredo, Huff and W B strains of Entamoeba histolytica were grown in Nelson's encystment medium. When numbers of mature cysts were noted, the entire culture was fixed in buffered glutaraldehyde and post osmicated. Embedment was in Araldite and sections were viewed in a Hitachi HU 11-A microscope. With this method trophozoites and cysts in all stages of maturation were obtained.In the precyst, the first indication of the formation of the cyst wall is the appearance of a fuzzy coat on the plasmalemma of the rounded up trophozoite. Subsequently, exterior to the coat, a thick electron lucid area appears, which may contain debris from the culture medium.
Transitional Forms of Langerhans Cell Granules in Letterer-siwe Disease
Authors: Shamoto M. , Millhouse E. W. 
Published: June 2020

Recently, Langerhans cell granules have been observed not only in the Langerhans cell of normal human epidermis, but also in the histiocytes of Letterer-Siwe disease. The fact that the same Langerhans cell granules have been observed in such unrelated material has aroused interest and led to various speculations regarding their mode of formation.Biopsy specimens were obtained from the left cervical lymph node (Figs. II, III) of a 17 month old Japanese boy. Autopsy specimens were obtained 19 days later from a left cervical lymph node, spleen (Fig. I), liver (Fig. IV), thymus, and skin.
Fine Structure of Sea Urchin Sperm Membranes
Authors: Inoue S. , Buday A. , Cousineau G.H. 
Published: June 2020

From electron microscope studies of thin sections it is known that the entire surface of a spermatozoon of sea urchin is covered by a plasma membrane, or sperm membrane, of an approximate thickness of 100Å (1). In these experiments the surface replica method was applied for the study of the fine structure of the sperm membrane.Spermatozoa from Strongylocentrotus purpuratus (sea urchins supplied by the Pacific Biomarine Supply Company, Venice, Calif.) were washed several times by centrifugation in Millipore-filtered sea water. After fixation in a 2.5% glutaraldehyde-paraformaldehyde (sea water mixture at 4°C) for an hour, spermatozoa were washed with sea water and then with distilled water for several times. A few drops of specimen were dried on a glass slide and the surface replica was prepared according to the method previously described (2) with the exception that the spermatozoa were decomposed in 18 N H2SO4 for about 20 hours at room temperature. The replica films were examined with a JEM-7A electron microscope.
Oogenesis in Dirofilaria Immitis
Authors: Lee Chin-Chiu , H. Miller Joseph 
Published: June 2020

The ultrastructural aspects of oocyte development in Dirofilaria immitis was studied with reference to the phylogenesis of mitochondria. Segments of ovaries from mature female worms were fixed in glutaraldehyde, postosmicated, dehydrated with ethanol, and embedded with Araldite 502. Thin sections from defined regions of ovaries were stained with uranyl acetate and lead citrate and viewed with a Hitachi HU-11A microscope. The method of Scarpelli, et al.. (1962), utilizing tetranitro-blue tetrazolium, was used for detecting the presence of succinic dehydrogenase and NADH-cytochrome c reductase.Cells from the germinal zone (within 5 cm. from the tip of ovary) are round and uniform in size. They have pseudppod-like processes (Fig. 1) by which they are interconnected. They possess a simple cytoplasmic organization and contain very few organelles (Fig. 2). The latter include the nucleus, nucleolus, lysosome-like granules, lipid droplets, scanty ribosomes, Golgi complex, and rudimentary mitochondria.
Electron Microscopy of Cells Infected with Adenovirus Type 12
Authors: SUN C. N. 
Published: June 2020

The presence of non-viral paracrystalline protein in cells infected with adenovirus type 5 (2) and adenovirus type 2 (4) has been reported.The present studies revealed adenovirus type 12 produced: (a) paracrystalline bodies in KB cells morphologically similar to that induced by adenovirus type 5 and (b) small crystalline lattices which consisted of tubular subunits.The sequential developmental studies of adenovirus type 12 were made in KB cells and in cell lines derived from human origin. In the infected KB cells, the intranuclear patches and stipplings were clearly seen beginning at 18th hour of inoculation (Fig. 1).
New Techniques in Scanning Electron Microscopy
Authors: Ogilvie Robert E. , Sutfin Lloyd V. 
Published: June 2020

The scanning electron microscope is one of the most exciting tools to be applied to the study of materials. However, it has been a logical development to equip the SEM with X-ray spectrometers and in particular solid-state energy dispersion detectors. Other relatively new techniques include Auger electron spectroscopy, Scanning Mirror Microscopy, Coates patterns and a variety of techniques for potential mapping of integrated circuits.Because of limited time and space we will limit this discussion to the use of the solid-state energy dispersion detector.Often it is desirable to know the chemical nature of the topographical features of a specimen being studied. Both dispersive and energy dispersion techniques can be used in most cases, however, the energy dispersive technique has many advantages over the dispersive system. The main advantage is the much higher X-ray efficiency and less stringent requirements on specimen geometry.
The Alignment of the Cheistov High Intensity Grip Cap in the Rca Emu-3 And Emu-U Electron Microscopes
Authors: J. Lloyd Bolivar , Christov George 
Published: June 2020

The Christov high intensity grid cap (1,2) is being used in RCA EMU-3 and EMU-U electron microscopes with increasing frequency as more investigators are discovering the augmentation of the illumination which permits easy and accurate focus at all magnifications. However, as some operators are not too familiar with the alignment of the new grid cap, it is our purpose to present a simple method of alignment.Because of the small aperture in the high intensity grid cap, it requires cleaning more often than the standard cap. The filament is aligned in the gun using the filament alignment tool as usual. Then the high intensity cap (held in a lens paper) is carefully threaded onto the gun assembly with the three nylon screws threaded in place so that they do not protrude inside of the cap.
Annealing Of Radiation Damage in Tungsten
Authors: Rau Robert C. , Moteff John 
Published: June 2020

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.
The Characterization of a Grain Boundary by Transmission Electron Microscopy
Authors: Horylev R.J. , Murr L.E. 
Published: June 2020

Read has shown that an arbitrary grain boundary has five degrees of freedom associated with it. Three degrees of freedom are necessary to describe the orientation of one grain with respect to the other, while the remaining two degrees of freedom position the boundary plane between the adjacent grains.Figure 1(a) depicts a general twin boundary-grain boundary intersection. The degrees of freedom for the grain boundary are represented by (HKL)1, (HKL)2, Θ, θGB, ø. Two degrees of freedom are contained in the surface orientations of the grains.
Electron Microscope Observations of Mechanical Metamorphism in Iron Meteorites
Authors: Faulkner D. , Lorimer G.W. , Axon H.J. 
Published: June 2020

It is now generally accepted that meteorites are fragments produced by the collision of parent bodies of asteroidal dimensions. Optical metallographic evidence suggests that there exists a group of iron meteorites which exhibit structures similar to those observed in explosively shock loaded iron. It seems likely that shock loading of meteorites could be produced by preterrestrial impact of their parent bodies as mentioned above.We have therefore looked at the defect structure of one of these meteorites (Trenton) and compared the results with those made on
a) an unshocked ‘standard’ meteorite (Canyon Diablo)b) an artificially shocked ‘standard’ meteorite (Canyon Diablo) andc) an artificially shocked specimen of pure α-iron.
Ion Etching Studies with Varied Materials
Authors: Thompson George R. 
Published: June 2020

With the evolution of ion thinning in the latter 50's and its acceptance and application by the microscopist in the last few years, attention has been focused on the ability to prepare specimens from a polycrystalline or multiphase materials for transmission electron microscopy. Subsequent to the initial and significant results with alumina, work has been undertaken to show the versatility of this technique with a wide variety of materials. It is the purpose of this paper to describe the numerous types of ion etched specimens which have been successfully analyzed. Experience involving hundreds of specimens prepared with an Ion Micro Milling Instrument, often called IMMI.The electronic industry has found uses for this type of,equipment with semiconductor materials such as silicon, germanium, gallium arsenide, gallium phosphate, barium titinate, and niobium tin. The most work to date has been done with silicon. Fig. 2 shows a recent photomicrograph of GaAs where lattice planes are visible throughout the matrix. Extensive research has been undertaken with ceramic materials including aluminum oxide, zerconia, and magnesium oxide.
Dislocations, Ordering and Antiferromagnetic Domains in MnO
Authors: Barber D. J. , Evans R. G. 
Published: June 2020

Manganese (II) oxide, MnO, in common with CoO, NiO and FeO, possesses the NaCl structure and shows antiferromagnetism below its Neel point, Tn∼ 122 K. However, the defect chemistry of the four oxides is different and the magnetic structures are not identical. The non-stoichiometry in MnO2 small (∼2%) and below the Tn the spins lie in (111) planes. Previous work reported observations of magnetic features in CoO and NiO. The aim of our work was to find explanations for certain resonance results on antiferromagnetic MnO.Foils of single crystal MnO were prepared from shaped discs by dissolution in a mixture of HCl and HNO3. Optical microscopy revealed that the etch-pitted foils contained cruciform-shaped precipitates, often thick and proud of the surface but red-colored when optically transparent (MnO is green). Electron diffraction and probe microanalysis indicated that the precipitates were Mn2O3, in contrast with recent findings of Co3O4 in CoO.
Interference Experiments with a Field Emission Source
Authors: Crewe A. V. , Saxon J. 
Published: June 2020

Field emission from a tungsten tip provides a source with very high brightness and high partial coherence. An electron gun of low spherical aberration is used to focus the electrons from the tip to a small spot about 100 Å in diameter. Since the voltages applied to the tip and gun are stable to better than 5 ppm, the temporal coherence is limited by the energy spread of the source, about 200 mv.Using the focused spot a few centimeters below the gun as an effective source, a metalized quartz fiber about 2 μ in diameter is positioned a few centimeters below the source, as shown in Fig. 1. Two cylindrica11y symmetric magnetic lenses are used to magnify the resulting Fresnel diffraction pattern. The image is produced on a fluorescent coating deposited on the vacuum side of a fiber optic window. The image is recorded directly on film placed against the window outside the vacuum system.
A Comparison of Scanning and Fixed Beam High Voltage Electron Microscopy
Authors: Cowley J. M. 
Published: June 2020

Since the theoretical advantage of high voltage microscopy in terms of improved resolution has not yet been achieved, the justification for the building of high voltage microscopes has been mainly the possibility of studying thicker specimens plus the observation of some radiation damage and some relativistic n-beam dynamical diffraction effects. For most of these purposes the scanning mode of transmission electron microscopy has clear advantages.As in the case of the fixed beam instrument (FBI), the limitation on resolution of the scanning transmission electron microscope (STEM) for ideal thin specimens is determined largely by instabilities of the high voltage supply and lens currents and by mechanical instabilities. In this respect the STEM suffers from the disadvantage that the point-by-point recording of the image involves a greater recording time and hence greater sensitivity to long term instabilities.
Fasciaton of Pectate Elementary Fibrils
Authors: Leeper George F. 
Published: June 2020

Polysaccharide elementary fibrils are usually fasciated into microfibrils of from one hundred to a few hundred Angstroms wide. Cellulose microfibrils when subjected to acid treatment dissociate into component elementary fibrils. For pectic acid it was observed that variations in pH could cause a change in the fasciation of the elementary fibrils.Solutions of purified pectic acid and sodium phosphotungtate were adjusted to various pH levels with NaOH or HCl and diluted to give a final concentration of 0.5 and 1% for the polysaccharide and negative stains respectively. Micrographs were made of the samples after drying on a carbon film covered grid. The average number of elementary fibrils was determined by counting the number of elementary fibrils in each fascicle intersected by lines drawn across the micrograph.
Structure of Grain Boundaries in Metals and Alloys: Direct Observations in the TEM
Authors: Murr L. E. 
Published: June 2020

Many models of grain boundaries in metals and alloys have been developed in attempts to interpret their properties and observed structures. Because of the complexity of grain boundary structure, it is generally possible to apply any of the proposed models in any material, and to describe grain boundaries as possessing dislocation structures, ledges, protrusions, island structures, facets, coincidence regions which exhibit good atomic fit and establish a kind of superlattice array, and combinations of these structural features.The dislocation nature of small angle grain boundaries is well known, consisting of tilt or twist arrays or combinations of edge or screw dislocations.
Field-Ion Microscopy of BCC Metals: A Study of Image Differences and Topographical Variations
Authors: Inal O. T. , Murr L. E. 
Published: June 2020

When sharp metal filaments of W, Fe, Nb or Ta are observed in the field-ion microscope (FIM), their appearance is differentiated primarily by variations in regional brightness. This regional brightness, particularly prominent at liquid nitrogen temperature has been attributed in the main to chemical specificity which manifests itself in a paricular array of surface-atom electron-orbital configurations.Recently, anomalous image brightness and streaks in both fcc and bee materials observed in the FIM have been shown to be the result of surface asperities and related topographic features which arise by the unsystematic etching of the emission-tip end forms.
A Fabric Study of Clay Floccules
Authors: Naymik T. G. 
Published: June 2020

Authigenic clays have been favored in SEM clay studies due to their large crystallite size, well developed individuals and open texture. Detrital clay material which is less stable under the electron beam, shows poor crvstal morphology and in general, smaller particle size is more difficult to observe.Specimen preparation is extremely important for viewing detrital clays. The main difficulty in photographing clays lies in the edge brightening effect inherent in clay platelets. Edge brightening arises from charging due to water migration from between clav platelets to the edges and from high atomic number coating material (gold) which tends to concentrate at the edges.
S.E.M. Observations of Quartz in Cherts: Etched vs. Unetched Surfaces
Authors: Jendrzejewski John P. , Knauth L. Paul 
Published: June 2020

Cherts, rocks composed essentially of microcrystalline quartz, display a wide variety of crystal forms. Fractured and polished surfaces of a bedded and a nodular chert were examined with the S.E.M. before and after being etched in various solutions (HF, KOH, NaOH). The bedded chert is a member of the Arkansas Novaculite containing pyrite, organic matter, and silicified organic spherical bodies (possibly spores) 100-500 microns in diameter. The chert nodule is from a Cretaceous carbonate, and displays a white patina which is interpreted as a weathering rind.Unetched surfaces generally do not display crystal morphologies as well as etched surfaces. However, crystal forms were observed on unetched surfaces where the fracture exposed cavities within the rock.
Electron Microscopy and X-Ray Microanalysis in Forensic Science
Authors: Johnson James W. , Brown John L. 
Published: June 2020

Forensic science has been described as an application of all disciplines of science in matters of jurisprudence. As society and technology advance, more sophisticated analytical techniques must be applied to the investigation of crime and the determination of fault in civil suits. The legal investigator must work constantly to keep abreast of new methods and their proper application.The examination of physical evidence has been the most important means of determining the facts of a given case. Personal inspection of evidence with the unaided eye and optical microscope have long been used and have become accepted in court room testimony.
A Technique For The Rapid Determination of the Contrast Transfer Characteristics of an Electron Microscope
Authors: Krakow William , Downing Kenneth H. , Siegel Benjamin M. 
Published: June 2020

A focal series of a thin carbon film in bright-field phase contrast has been used by Thon to obtain a family of curves that represent the contrast transfer characteristics of a particular objective lens as a function of the defocus value. The thin carbon film is assumed to be a weak phase object, and the light optical diffractogram gives the Fourier transform of each micrograph from which the relative contrast at each spatial frequency can be obtained for the corresponding amount of defocus.We have obtained the equivalent information from a single electron micrograph of a thin carbon film specimen tilted at a large angle (65°), see Fig. 1.
Field Emission SEM Equipped With Noise Compensator
Authors: Saito S. , Todokoro H. , Nomura S. , Komoda T. 
Published: June 2020

Field emission scanning electron microscope (FESEM) features extremely high resolution images, and offers many valuable information. But, for a specimen which gives low contrast images, lateral stripes appear in images. These stripes are resulted from signal fluctuations caused by probe current noises. In order to obtain good images without stripes, the fluctuations should be less than 1%, especially for low contrast images. For this purpose, the authors realized a noise compensator, and applied this to the FESEM.Fig. 1 shows an outline of FESEM equipped with a noise compensator. Two apertures are provided gust under the field emission gun.
Electron Microscopic Observations of a Human Brain Abscess
Authors: Sekhon Sant S. 
Published: June 2020

A brain biopsy taken from an abscess located in the left temporal region of a 55-year-old caucasian male provided the basis for the present observations. The patient had a history of viral encephalitis, and a chronic brain syndrome secondary to this. He also had a positive history of grand mal seizuies probably from the viral encephalitis. The main objectives of this study were to demonstrate if possible the presence of viral particles in nerve cells and to observe and describe ultrastructural alterations and other morphological expressions of cell injury.Brain tissue from the abscess area was fixed in 2.5% cacodylate-buffered glutaraldehyde-formaldehyde mixture and post-fixed in 1% cacodylate-buffered osmium tetroxide, dehydrated and embedded in Araldite. The sections were stained with a combination of uranyl acetate and lead citrate and examined under RCA EMU 3E electron microscope.
Preparation of Helminths For Scanning Electron Microscopy
Authors: Weise Robert W. 
Published: June 2020

The role that scanning electron microscopy (SEM) is playing in descriptive helminthology is becoming more apparent in the literature. However, the majority of papers on the SEM of helminths have used conventional or modified light microscope techniques of fixation and dehydration, and not established SEM techniques in which freeze- and critical point-drying are routinely used. The present investigation was undertaken to examine the applicability of modified scanning and transmission electron microscope techniques for the preparation of certain helminths for SEM.Method I.– Live animal-parasitic nematodes were fixed in 6% phosphate buffered glutaraldehyde for 24 hr at room temperature.
Application of Improved Voltage Compensation in the SEM to Imaging of Organic Materials
Authors: Killingworth P.J. , Warren M. 
Published: June 2020

Ultimate resolution in the scanning electron microscope is determined not only by the diameter of the incident electron beam, but by interaction of that beam with the specimen material. Generally, while minimum beam diameter diminishes with increasing voltage, due to the reduced effect of aberration component and magnetic interference, the excited volume within the sample increases with electron energy. Thus, for any given material and imaging signal, there is an optimum volt age to achieve best resolution.In the case of organic materials, which are in general of low density and electric ally non-conducting; and may in addition be susceptible to radiation and heat damage, the selection of correct operating parameters is extremely critical and is achiev ed by interative adjustment.
Inheritance of Intracellular Bacteroids in Periplaneta Americana
Authors: Daniel R. S. 
Published: June 2020

Blockmann was the first to assume that intracellular symbiotic bacteroids of blattids are transmitted to progeny through the ovaries of the parent. Subsequent literature has generally supported the transovariole transmission theory, but whether bacteroids infect differentiated oocytes or ovarian anlage has not been determined. This paper presents electron microscopic data relevant to the question of bacteroid inheritance.Ovaries of P. americana were fixed in cacodylate buffered glutaraldehyde and osmium then block-stained in uranyl acetate. Sections were stained with uranyl acetate and lead citrate. Serial sections (Fig 1 insert) of germaria (Zone II) reveal that bacteroids are absent in formative follicle cells (Fig 1), oogonia (Fig 2) and intercellular spaces of germinal tissue in adults and nymphs.