bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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.
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.
The Application of Ferritin-Tagged Antibodies in Viral Diagnosis by Electron Microscopy
Authors: Breese S. S. , Dardiri A. H. 
Published: June 2020

In the late summer of 1970, blood and excised skin nodules from an outbreak of disease in cattle in northern Minnesota were received for diagnosis. Clinical signs in a herd of 17 dairy cattle suggested the possibility of lumpy skin disease, a viral infection found primarily in South Africa.Lesion material and blood samples were passed in primary calf kidney tissue culture. Examination of third passage cultures showed typical herpes virus particles. Bovine herpes virus has been described in England as bovine herpes mammillitis and in South Africa as Allerton virus. These exotic strains of bovine herpes virus and the pox virus (Neethling) presumed to be the causative agent of lumpy skin disease, were also grown in calf kidney tissue culture.Relationships between these viruses were demonstrated by cross-tagging using specific bovine antisera to each virus and rabbit-anti-bovine serum conjugated with ferritin. Infected tissue cultures in 4-oz. prescription bottles were scraped from the glass and collected in conical tubes in a clinical centrifuge. The cell pellets were gently resuspended first with 0.2 ml of a suitable dilution (1, 1/2, 1/4, 1/8) of each bovine antiserum and allowed to react at room temperature for 30-40 min. They were then washed 3 X with phosphate buffer (PB) and resuspended a second time in a suitable dilution (1, 1/2, 1/4) of rabbit-anti-bovine serum conjugated to ferritin. Antiserum to duck plague (an avian herpes virus) was used as a control.
Fine Structure of Nerve Cells in the Brain of the House Fly, Musca Domestica (Diptera)
Authors: Allison Venita F. , Sharma Suraj P. , Sohal R. S. 
Published: June 2020

Because of its comparative structural simplicity insect central nervous system has been frequently used for basic neurological studies. However, relatively little is known regarding the cytological organization of the different neuronal types, especially at the fine structural level. The precise localization and identification of particular cell types within the brain would be useful in correlating structural characteristics of neurons with their integrative functional role. The present study reports the fine structure of three different types of nerve cells within the anterior protocerebral region of the brain of the adult male house fly, Musca domestica.Type I Neuron (Figure 1): Examination of the anterior lateral region of the protocerebrum reveals a small population of uni-polar neurons further characterized by perikarya with a paucity of cytoplasm and proportionately large dense nuclei. The cytoplasm contains poorly developed endoplasmic reticulum, an abundance of ribosomes and a few ovoid to rounded mitochondria with shelf-like cristae. Small Golgi regions and dense inclusion bodies are seen in certain planes of section.
Retrieval of Frozen Surgical Material for Electron Microscopic Examination
Authors: Hedley-Whyte E. T. , Gilles F. H. 
Published: June 2020

During a study of frozen sections of rectal biopsies in neurologic disease of children we wished to examine particular neurons in the electron microscope. We therefore investigated the use of frozen surgical tissue for electron microscopic examination.Fresh tissue was frozen in liquid isopentane pre-cooled in dry ice and then stored at -80°C. 1-30 days later 16 - 20 μm cryostat sections were picked up on slides or coverslips previously coated with 10% gelatin and immersed in 5% cacodylate buffered glutaraldehyde for 30 mins. to 1 hour at room temperature. The sections were rinsed in Sabatini's washing solution (3 times, 3 minutes each) and post-fixed in Dalton's chrome osmium (30 mins.). Dehydration in graded acetones and propylene oxide and infiltration with Epon-araldite were accomplished at room temperature. In-block staining was carried out in 1% uranyl acetate in 70% acetone for 1 hour. The slides were inverted over flat embedding molds filled with an Epon-araldite mixture and polymerised at 60°C.
Ultrastructural Changes of Canine Kidneys During 24-Hour Perfusion on a LI-400 Preservation System
Authors: Magnusson M. O. , Osborne D. G. , Shimoji T. , Kiser W. S. , Hawk W. A. 
Published: June 2020

Short term experimental and clinical preservation of kidneys is presently best accomplished by hypothermic continuous pulsatile perfusion with cryoprecipitated and millipore filtered plasma. This study was undertaken to observe ultrastructural changes occurring during 24-hour preservation using the above mentioned method.A kidney was removed through a midline incision from healthy mongrel dogs under pentobarbital anesthesia. The kidneys were flushed immediately after removal with chilled electrolyte solution and placed on a LI-400 preservation system and perfused at 8-10°C. Serial kidney biopsies were obtained at 0-½-1-2-4-8-16 and 24 hours of preservation. All biopsies were prepared for electron microscopy. At the end of the preservation period the kidneys were autografted.
Intranuclear Inclusions in the Human Osteogenic Sarcoma Cells
Authors: Yasuzumi G. , Sakamoto H. , Matsuo T. 
Published: June 2020

The intranuclear inclusion formation was observed in the human osteogenic sarcoma cells obtained from three patients, which were fixed in glutaraldehyde, postfixed in osmium tetroxide and embedded in epoxy Epon resin. Thin sections were stained doubly with uranyl acetate followed by lead citrate. They were examined with an electron microscope, model JEM-100B, HU-11DS or HU-12.The sarcoma cell nuclei were differentiated at least into two types according to their chromatin contents: one was abundant in components which were closely associated with a large nucleolus and the nuclear envelope, of found isolated in the nucleoplasm; while the other was relatively electron lucent, showing only a few amounts of chromatin granules dispersed in the nucleoplasm, though the nucleolus is large in size and the nucleolonemata are clearly identified. Such a structure is similar to that observed in the hyperplastic liver nodules in the rat induced by several hepatocarcinogens.
Immunoelectron Microscopy of Type C Virus Particles Produced in a Cell Line Derived from Pleural Effusion of a Lymphoma Patient
Authors: Shigematsu T. , Priori E. S. , Dmochowski L. , Wilbur J. R. 
Published: June 2020

A monolayer culture (ESP-1) was established with cells obtained from pleural effusion of a patient with Burkitt lymphoma (American type). Virus particles, similar to murine type C virus particles, were first observed in cells of the 10th passage of the culture. Mature and immature, including budding, virus particles were frequently found in all subsequent passages of this continuous culture (including 28th).A human tumor cell line continuously producing type C virus particles provides a valuable new system for immunological studies of such virus particles.
Tracing Permeation Pathways Across Epithelia
Authors: Tormey J. McD. , Wright E. M. , Smulders A. P. 
Published: June 2020

The route by which small molecules, such as water, electrolytes and sugars, cross the membranes of epithelial tissues is a central problem in biological transport. Good methods for quantitatively localizing small diffusible molecules within tissues, or for unambiguously demonstrating membrane transport sites, have yet to be developed. In their absence indirect approaches based on anatomical changes have had to be used.The lateral intercellular spaces of gall bladder epithelium were several years ago found to be widely dilated when salt and water were being actively pumped across the tissue. The spaces were collapsed in the absence of transport. Similar phenomena were subsequently observed in several other tissues. This has been widely interpreted as proof that the spaces are the route of fluid transport.
Formation of Transport Coated Pits and Vesicles Uniquely Stimulated by Exogenous Yolk Proteins in in vitro Oocytes
Authors: Roth Thomas F. , Dodson John , Boss Barbara 
Published: June 2020

We have characterized several systems that exhibit selective protein sequestration in order to use them as model systems to elucidate the mechanisms of specific protein endocytosis. One of these, the mosquito ovary, is ideal because it contains synchronous oocytes and is easily cultivated in vitro. To date we have characterized the yolk proteins, established that the oocytes selectively sequester yolk proteins and that the oocytes effectively exclude other proteins. The transport exhibits saturation kinetics typical of active transport and is inhibitable.To establish the morphological basis of this selection, we incubated ovaries that had been previously active in laying down yolk (24 hr post blood meal) in an in vitro culture with either yolk protein, ferritin, IgG, albumin, or a combination of these proteins. We confirmed earlier observations that significant transport occurs only in the presence of yolk proteins.
Scanning and Transmission Microscopy of Nematocyst Batteries in Epitheliomuscular Cells of Hydra
Authors: Westfall Jane A. , Yamataka S. , Enos Paul D. 
Published: June 2020

Scanning electron microscopy (SEM) provides three dimensional details of external surface structures and supplements ultrastructural information provided by transmission electron microscopy (TEM). Animals composed of watery jellylike tissues such as hydras and other coelenterates have not been considered suitable for SEM studies because of the difficulty in preserving such organisms in a normal state. This study demonstrates 1) the successful use of SEM on such tissue, and 2) the unique arrangement of batteries of nematocysts within large epitheliomuscular cells on tentacles of Hydra littoralis.Whole specimens of Hydra were prepared for SEM (Figs. 1 and 2) by the fix, freeze-dry, coat technique of Small and Màrszalek. The specimens were fixed in osmium tetroxide and mercuric chloride, freeze-dried in vacuo on a prechilled 1 Kg brass block, and coated with gold-palladium. Tissues for TEM (Figs. 3 and 4) were fixed in glutaraldehyde followed by osmium tetroxide. Scanning micrographs were taken on a Cambridge Stereoscan Mark II A microscope at 10 KV and transmission micrographs were taken on an RCA EMU 3G microscope (Fig. 3) or on a Hitachi HU 11B microscope (Fig. 4).
Delicate Botanical Specimens Preserved for Scanning Electron Microscopy by Critical Point Drying
Authors: Cohen Arthur L. , Garner Gerald E. 
Published: June 2020

The surface forms and structures of animal cells have been strikingly preserved for scanning electron microscopy by freeze-drying and by critical point drying both by the method with CO2used as the transitional fluid and the later procedure which uses a fluorocarbon (Freon 13) as a medium for the transition from the liquid to the gaseous environment. Freeze-drying is often prolonged (5-12 hours as compared with an hour or less by the critical point method) and in our experience with mold cultures on agar, the substrate shrivels and cracks and hyphal filaments are distorted.Despite, and possibly because of a flexible but inelastic cell wall, plant cells often show greater distortion than do animal cells after evaporative drying or replacement dehydration for mixrotechnical work. The animal cell membrane can contract more or less uniformly on drying - as shown by the numerous micrographs of well-preserved erythrocytes, while plant cell walls often crumple. The many scanning electron micrographs of partially collapsed pollen grains bear witness to this fact.
Microbodies (Peroxisomes) in Sebaceous Glands
Authors: Hruban Z. , Vigil E. L. , Martan J. 
Published: June 2020

The cells of the supracaudal gland of guinea pig have abundant cytoplasm, round and ovoid mitochondria, abundant free ribosomes, a few rough cisternae, abundant vesicular reticulum, complex agglomerates of tubular reticulum, a few residual bodies and a few multivesicular bodies. Golgi complex is small. Electron lucid lipid droplets are numerous. Cell membranes interdigitate. Desmosomes and tonofibrils are frequent. Single membrane limited particles 200-300 mμ in diameter show close spatial relations to cisternae and lipid droplets (Fig. 1). Glutaraldehyde fixed tissue reacted for demonstration of catalase identifies these particles as microbodies at light (Fig. 3) and EM (Fig. 5) level. Aminotriazole abolishes reaction.The uropygial or preen gland of hen is composed of similar cells. Some lipid droplets contain lamellar or reticular material (Fig. 2). Rough reticulum is moderately abundant and lumina contain pale droplets or liposomes. Particles with dense matrix contain pale granules with lamellar substructure. Microbodies (Fig. 2) 200-800 mμ in diameter are numerous. They are associated with ER, lipid or cisternae containing dense fibrils (Fig. 7). DAB reaction is positive at light (Fig. 4) and EM (Fig. 6) level. It is abolished by aminotriazole. Specific activities of catalase in homogenates of both glands are about 50% of those found in livers.
Ferritin-Conjugated Plant Agglutinins as Specific Stains for Cell Surface Saccharides
Authors: Nicolson G. L. , Singer S. J. 
Published: June 2020

Plant agglutinins are proteins which bind to specific sugar ligands. For the ultrastructural localization of specific saccharides, we have now conjugated two different plant agglutinins with ferritin (Fer): concanavalin A (Con A), which binds specifically to sugars sterically related to D-glucose and D-mannose, and ricin (Ric), specific for sugars related to D-galactose and L-rhamnose.The conjugates Fer-Con A and Fer-Ric are prepared as follows. To a solution containing 8% Fer and 2.5% purified agglutinin in a buffer (SPB) containing 0.5M NaCl, 0.05M Na phosphate, pH 6.8, is added with stirring freshly distilled glutaraldehyde to a final concentration of 0.05%. Alkaline pH must be avoided to prevent aggregation of the agglutinins. After 45 min. at room temperature the mixture is dialyzed against SPB containing 0.1M NH4Cl. The Fer-agglutinins are centrifuged to remove large aggregates and finally chromatographically purified on Agarose A-1.5m (Fer-ConA) or Biogel P300 (Fer-Ric).
Ultrastructural Effects of Sterols on L Cell Mouse Fibroblasts
Authors: Lipetz Jacques , Rothblat George H. 
Published: June 2020

Many mammalian tissue culture lines and strains have the capacity to synthesize sterol from a variety of precursors. Recently it has been shown that a mouse L cell line synthesizes desmosterol as its major sterol; however, if these cells are exposed to cholesterol in the medium, they stop synthesizing desmosterol and incorporate cholesterol. No pronounced differences were observed in the growth or gross morphology of these cells when synthesizing desmosterol or incorporating cholesterol from the medium. Ultrastructural comparisons of L cells growing in the presence or absence of cholesterol reveal few differences in their morphology (Figs. 1 and 2).As part of a larger study of various sterols, the effect of coprostanol, a steric isomer of cholestanol (dihydrocholesterol) was studied. Concentrations as low as 10 μg/ml of this sterol inhibits cell growth after two days. A sizeable proportion of the cells, however, remain adhering to the glass and are thus presumably still alive even after exposures as long as four days to concentrations as high as 40 μg/ml. This was substantiated by the trypan blue exclusion test.
Advances in High Voltage Electron Microscopy
Authors: Thomas L. E. , Lally J. S. , Fisher R. M. 
Published: June 2020

Diffraction contrast imaging in a HVEM differs from 100 kv electron microscopy mainly because of the increased importance of many-beam interactions among the systematic reflections from a given set of low index planes. Since the last annual EMSA meeting our understanding of the consequences of these interactions, in particular the marked changes in the diffraction conditions which give optimum transmission and defect contrast, has advanced rapidly. Progress in a number of related areas will be described.Transmission - Throughout the range 100-1000 kv maximum transmission occurs when the crystal is oriented for systematic diffraction from the lowest index reflecting planes. Relatively poor transmission always results when nonsystematic reflections are simultaneously excited. At 100 kv the Bragg deviation which maximizes transmission in the direct beam is just positive of the 1st order Bragg position, at k ∼ 0.6.
Characterization of Hyper-velocity Particle Impact Craters on Apollo 11 Lunar Soil
Authors: Devaney John R. , Evans Kenneth 
Published: June 2020

There exists on the visible surface of the moon, a continuous range of impact craters from the very large to those below the resolution limits of terrestrial telescopes. The RANGER, SURVEYOR and LUNAR ORBITER programs extended the knowledge of existent craters down to those several centimeters in diameter. Prior to the actual examination of lunar material returned by the Apollo 11 mission, a debate was being carried on as to whether craters from hyper-velocity particles existed in the microscopic realm. Soon after the first samples were examined via Scanning Electron Microscopy, the point in question was settled with a definite affirmative.The initial effort in conjunction with Caltech scientist G. J. Wasserberg had as its goal the solution of two problems:
(1) Can impact craters be differentiated from bubble bursts?(2) What are the characteristics of impact craters?To pursue the first problem initial efforts were designed to study samples with low possibility of bubbles or voids. This resulted in the examination of a chip of lunar feldspar with a large pit on its exposed surface.
Ultrastructure of Developing Granulosa and Theca Cells
Authors: Baccarini Iracema M. 
Published: June 2020

The embryology of granulosa and theca cells is not understood thoroughly. Electron microscopic studies in the past have been concerned mainly with mature granulosa cells and less with their development.Material and Methods. Rat fetuses were removed surgically under ether anesthesia at 16-17, 17-18 and 18-19 days of gestation. Their abdominal cavities were opened, and the fetuses were placed immediately into 3% glutaraldehyde (pH 7.2) for 3 hours. During this time, the fetal ovaries were dissected under a microscope. The tissue was washed in phosphatebuffer for 24 hours, post-fixed in 1% phosphate buffered osmium tetroxide for 1-2 hours at 4°C, and embedded in Durcupan ACM (Fluka). Sections were double stained with uranyl acetate and lead citrate, and viewed in an RCA-EMU-3D electron microscope.