bluuebunny/crossref_metadata_2025_split huggingface dataset:
Precipitation in Partially-Stabilized Zirconia
Authors: Porter D. L. , Heuer A. H. 
Published: June 2020

Precipitation in commercial partially-stabilized zirconia (PSZ) has been studied in order to facilitate "alloy design" in these materials. The commercial material used in this study is a 2.8 wt. % MgO alloy and has the cubic flourite structure at its sintering temperature. Upon cooling, a nearly MgO-free ZrO2 phase with tetragonal symmetry precipitates, which on further cooling inverts martensitically to a phase with monoclinic symmetry. At room temperature, commercial PSZ's therefore consist of a cubic solid solution matrix containing monoclinic precipitate; size, morphology, and distribution of the precipitate phase strongly influence mechanical properties.Figures I and II show typical microstructures of the material as it is commercially produced. Both large and small precipitates are present (Figure I), indicative of precipitation over a range of temperatures during slow cooling through the two-phase region. Figure II shows heavily-twinned monoclinic particle; such large particles produced during commercial fabrication are believed to be deleterious to the mechanical behavior.
Effect of Steroids on Uterotubal Junction: An Ultrastructural and Cytochemical Study
Authors: Nayak R. K. , Wu A. S. H. 
Published: June 2020

The morphology, and histology of mammalian uterotubal junction have been extensively studied. Only a limited number of electron microscopic studies on this organ have been published. Furthermore, adequate data on the fine structure and ultracytochemistry of this organ are not available. Investigation of this subject, therefore, was initiated on the tubal junction of the intact prepubertal and ovariectomized rabbit to delineate changes induced by near physiologic levels of exogenous estrogen and progesterone. Experimental procedure is the same as reported previously.Two distinctive cell types, namely ciliated and secretory, are observed in the epithelia. The most obvious change after hormonal stimulation is the regeneration of cilia and basal bodies in the ciliated cells and the frequent extrusion of mucin-like granules into the tubal lumen (Figs. 1,3,4). Polysomal associations and fibrous granules are frequently seen in the cytoplasm of ciliated cells.
Structural Organization and Distribution of Fiber Types in Extraocular Muscles of Cats
Authors: Nag Asish C. , Peachey Lee D. 
Published: June 2020

Cat extraocular muscles consist of two regions: orbital, and global. The orbital region contains predominantly small diameter fibers, while the global region contains a variety of fibers of different diameters. The differences in ultrastructural features among these muscle fibers indicate that the extraocular muscles of cats contain at least five structurally distinguishable types of fibers.Superior rectus muscles were studied by light and electron microscopy, mapping the distribution of each fiber type with its distinctive features. A mixture of 4% paraformaldehyde and 4% glutaraldehyde was perfused through the carotid arteries of anesthetized adult cats and applied locally to exposed superior rectus muscles during the perfusion.
Morphometric Analysis of the Slow-Twitch Fibers of the Guinea Pig
Authors: Eisenberg Brenda R. , Kuda Aileen , Peter J. B. 
Published: June 2020

The soleus muscle of adult guinea pigs is composed entirely of slow-twitch fibers which stain moderately for oxidative enzymes and lightly for myofibrillar ATPase. The homogeneity of fiber type allows a quantitative ultrastructural study to be made by the point counting stereological method of Weibel. Longitudinal sections of well-fixed muscle fibers were used to obtain the preliminary morphometric data. This analysis excludes the region within 1 µ of the sarcolemma where there may be a higher volume fraction of mitochondria. Transverse sections were taken to provide additional anatomical information.The mitochondria, which are elongated, are not uniformly distributed along the length of the fiber but tend to lie on either side of the Z disc (Figs. 1 and 4) and are sparse in the A band (Figs. 1 and 3).
Changes in Light and Dark Adapted Planarian Photoreceptors
Authors: Carpenter Kay S. , Morita Michio 
Published: June 2020

The planarian Dugesia dorotocephala was used as the experimental animal to study the ultrastructure in the photoreceptor cell under different light parameters. The experimental groups studied were nine days dark adapted (DA), nine days natural light cycle (LA), and nine days dark adapted followed by ten minutes light exposure (DA + LE). A red light was used for feeding and cleaning the dark adapted animals. Fixation was in 2.5% glutaraldehyde followed by 1% OsO4.The most noticeable changes occured in the stalk area of the receptor cell located directly below the rhabdomeric microvilli. The mitochondria in light adapted animals were observed to exist in both swollen and contracted conditions.
Structural-Functional Correlations in Inner Ear Receptors
Authors: Lewis Edwin R. 
Published: June 2020

Transduction mechanisms are only partially understood in the sensory organs of the inner ear; and the roles of the receptor cells themselves with their magnificent elaborations of microvilli (stereocilia) and true cilia (kinocilia) are almost completely unknown. Certain clues are available, however. For example, scanning and transmission electron micrographs strongly suggest that the directional sensitivity known to be present in these receptors is imparted to them by the mechanical properties of the anisotropic array of stereocilia. Another clue may lie in the length and shape of the kinocilium.In bullfrog, Hillman found that, almost every receptor of the saccular macula has a kinocilium that is expanded at its distal end to form a large bulb (Fig. 1) which is connected to the tips of the several longest stereocilia and to the membrane supporting the otolith. Thus the entire kinocilium is no longer than the longest stereocilia.
The Electron Microscope in Clinical Diagnosis
Authors: Lee John C. 
Published: June 2020

Electron microscopic examination of surgical biopsy material is occasionally used in teaching hospitals as an aid to tissue diagnosis. Although the value of ultrastructural studies in a surgical pathology laboratory is undisputed in some instances, electron microscopy often merely serves to satisfy scientific curiosity and has little advantage over good light microscopy.In 1967 an electron microscope service unit was installed as part of the surgical pathology laboratory of the University of California, San Francisco, and has been utilized for ultrastructural studies on a fee-for-service basis. Some of the income of this laboratory is derived from fees paid from research grants for the examination of various experimental animal tissues. A large proportion, however, stems from fees for examining human biopsy material. Hospital insurance carriers are willing to pay reasonable amounts for this service when it benefits the patient.
Structural Changes in Animal Lungs Exposed to Low Concentrations of Ozone
Authors: Boatman E.S. , Sato S. , Frank R. 
Published: June 2020

There is considerable interest and speculation about the possible effects of ozone on the function and structure of the lung. Evidence is accumulating that ozone attacks the respiratory system at many levels including the larger more central airways, the smaller peripheral airways, components of the blood-air barrier and alveolar macrophages.The present study is concerned with the functional, morphological, and ultrastructural changes in the respiratory system of animals exposed to low concentrations (either 0.25, 0.5, or 1.0 ppm) of O3 for 3 hours. Both cats and rabbits were used.
Alveolar Surface Structure in Induced Acute Respiratory Insufficiency
Authors: Liss Robert H. , Molokhia Farouk A. , Daly Benedict D.T. , Ballantine Thomas V. N. , Norman John C. 
Published: June 2020

Death among patients following trauma, shock or sepsis is frequently attributable to a secondary episode of acute respiratory insufficiency. Initial hemodynamic problems may be successfully managed only to be followed by progressive, irreversible pulmonary failure.In this study, scanning electron microscopy has been used to assess alveolar surface topography in a canine model of induced respiratory insufficiency (ARI). Mongrel dogs were infused with saline intermittently, continually and continually with intermittent furosemide treatment. Ultrastructural and pathophysiologic correlates of ARI were seen only in dogs which were fluid-loaded continually at 100 ml/kg/hr for 4-6 hours, and not treated with furosemide.In acute pulmonary edema produced by continuous fluid overloading, the alveolar cell-air interface was altered. Scanning electron microscopy revealed focal pathology in edematous areas.
Structure and Transfer of Spermatozoa in Phoronopsis viridis
Authors: Zimmer Russel L. 
Published: June 2020

Spermatozoa of members of the phylum Phoronida are usually of a highly atypical V-shaped morphology and are characteristically packaged into spermatophores by the male. Neither the submicroscopic organization of the spermatozoa nor the functional significance of the spermatophore has been reported previously.Phoronopsis viridis were collected intertidally at Morro Bay, California. Spermatophores collected after release from the males were fixed in bicarbonate-buffered osmium tetroxide, dehydrated, embedded in epon, and sectioned for light and electron microscopy. Additionally, fresh spermatophores were placed on the lophophores of adults in EDTA-treated sea water; stages in the lysis of the spermatozoan mass through the tentacular wall were prepared at various intervals using the above procedure.
Fixation Induced Structural Changes in Chlamydomonas reinhardi (Wild Type) Chloroplast Membranes
Authors: Kretzer Frank 
Published: June 2020

The light reactions of photosynthesis (photolysis of water, photophosphorylation, and electron transport) require the structural integrity of the chloroplast membrane. This work attempts to chemically fix the chloroplast membrane of Chlamydomonas reinhardi (wild type) with minimal protein denaturation and lipid extraction. The molecular structure of these membranes can then be analysed in terms of their well defined biochemical functions.Previous work by others on chemically fixed chloroplast membranes demonstrated either a unit membrane or a membrane composed of a small uniform repeat subunit. However, if the molecular structure of these membranes is to be preserved, the protein must not be denatured and lipids must not be extracted. This rules out the classical fixatives (OsO4. KMnO4, high percentages of glutaraldehyde) and acetone or ethanol dehydration.
Glutaraldehyde-Urea, Copolymerized with Glycol Methacrylate by Ultraviolet Radiation, As An Embedment
Authors: Pease Daniel C. 
Published: June 2020

The proteins of tissues, embedded either in glutaraldehyde-urea polymerized under acidic conditions, or in glutaraldehyde-ammonia at neutrality, are poorly differentiated by conventional stains. In seeking an improved cytological image of protein systems in a water-containing embedment it was discovered that the glycol methacrylates (particularly hydroxyethyl methacrylate - HEM) can be truly copolymerized with a suitable glutaraldehyde-urea mixture. This was achieved by ultraviolet polymerization in the presence of trace amounts of benzoin, and with substantial water in the system. The chemistry involved is not yet understood.The resin mixture is freshly prepared before use, and consists of 6 ml HEM, 5 ml 50% glutaraldehyde, 1.5 gm urea, plus a trace of benzoin, with the pH adjusted to 6.0-6.5 with drops of strong NaOH.
Chloroplast Ultrastructure Preserved by a Water-Containing Glutaraldehyde-Urea Embedment
Authors: Nir Izhak , Pease Daniel C. 
Published: June 2020

Conventional techniques for preparing aldehyde-fixed chloroplasts for electron microscopy result not only in the loss of their lipids, but also their chlorophyll so that they become obviously bleached. This extraction is prevented by embedding in glutaraldehyde polymerized with urea in the presence of substantial quantities of water. Glutaraldehyde-fixed tissue then retains its green color into the final sections. As a consequence of these factors, ultrastructural arrangements and details of the grana membranes are thought to be preserved with unusual precision.The thylakoids appear in precisely ordered arrays, individually separated by uniform translucent gaps 15-20Å wide, particularly well seen in sections stained with OsO4, vapor (Fig. 1).
Hepatopancreatic Secretions in the Isopod, Oniscus ascellus
Authors: Roberts John W. , Witkus E. R. 
Published: June 2020

The hepatopancreas of the isopod, Oniscus ascellus, is comprised of two pairs of blind-ending diverticula which empty into the straight-line digestive system posterior to the foregut. The functional differentiation of the regenerative cells in the tip of each lobe was studied with the light and electron microscope by making alternate thick and thin sections from the blind-ending tip throughout the length of each lobe. Two types of cells specialized from the regenerative cells: B-cells, specialized for secretion and S-cells which function in absorption and storage of nutrients.In the B-cells, the secretory vesicles first appear in association with rough endoplasmic reticulum and Golgi apparatus in the transitional region of the lobe, between the regenerative and mature glandular cells (Fig. l).
Fine Structure of Pollen Grain Ektexine of Maize, Teosinte and Tripsacum
Authors: Banerjee Umesh C. , Barghoorn Elso S. 
Published: June 2020

Using light microscope (LM) it was found very difficult to distinguish the ektexine (outer sculptured layer of exine) pattern of maize (Zea mays L.) pollen grains from that of its wild relatives teosinte (Euchlaena mexicana Schrad.) and tripsacum (Tripsacum spp.). At the magnifications obtained by LM, the pollen grain ektexine is faintly granular or netted. By the use of electron microscopy, however, it is possible to characterize their pollen ektexine patterns.For scanning electron microscopy (SEM) acetolysed pollen grains were used. After acetolysis the pollen samples were washed several times in glass-distilled water to remove traces of acids. Each sample was dispersed in a drop of distilled water placed on specimen holders.
Spontaneous Production of Type C Virus Particles in a Culture Derived from Rat Embryo Cells
Authors: Priori Elizabeth S. , Shigematsu T. , Myers B. , Dmochowski L. 
Published: June 2020

Spontaneous release of type C virus particles in long-term cultures of mouse embryo cells as well as induction of similar particles in mouse embryo cell cultures with IUDR or BUDR have been reported. The presence of type C virus particles in cultures of normal rat embryos has not been reported.NB-1, a culture derived from embryos of a New Zealand Black (NB) rat (rats obtained from Mr. Samuel M. Poiley, N.C.I., Bethesda, Md.) and grown in McCoy's 5A medium supplemented with 20% fetal calf serum was passaged weekly. Extracellular virus particles similar to murine leukemia particles appeared in the 22nd subculture. General appearance of cells in passage 23 is shown in Fig. 1. Two budding figures and one immature type C virus particle may be seen in Fig. 2. The virus particles and budding were present in all further passages examined (currently passage 39). Various stages of budding are shown in Figs. 3a,b,c,d. Appearance of a mature virus particle is shown in Fig. 4.
Artefacts Occurring During Freeze-Etch Preparation
Authors: Maul Helmut M. , Maul Gerd G. , Wessing Armin 
Published: June 2020

Much effort has been put into the process to obtain undistorted biological specimens for use in electron microscopy. It has been well accepted that the main advantage of the freeze-etching method is to obtain cells stabilized in the living state. This method has proved to be a useful tool to study membrane structures. This communication deals with a number of artefacts which occur during the freeze-etching preparation.The effect of glycerol treatment as an anti-freeze agent on the cellular membranes has not yet been completely solved. The interpretation of results must take into account the physical treatment during the steps of preparation. In order to avoid decreased viability others have added glycerol incrementally; however, in some cases alterationsin cellular structure have been reported.
Loss of Absorbed Lipid During Processing of Intestine for Electron Microscopy
Authors: Buschmann Robert J. 
Published: June 2020

Since considerable, although variable, amounts of absorbed lipid are lost from intestinal epithelium during processing for electron microscopy, the following experiments were carried out to evaluate this loss during various, relatively new processing procedures.Everted sacs of rat jejunum were incubated in a micellar solution of oleic acid-3H (1.0 mM), monoolein (0.5 mM), and sodium taurocholate (15.0 mM) for 30 min at 37°C. Samples of these everted sacs were processed for electron microscopy by four different procedures which are outlined in TABLE I. The radioactivity lost to the processing solutions and remaining in the infiltrated tissue was monitored by liquid scintillation counting.Routine Processing included a single OSO4 fixation followed by ethanol (EtOH) dehydration, propylene oxide (PO) and Epon infiltration. The total loss of 3H-lipid was 67% of the total absorbed oleic acid-3H (TABLE II).
Incorporation of Cholesterol into Peripheral Nerve Myelin
Authors: Rawlins Frank A. 
Published: June 2020

Several speculations exist as to the site of incorporation of preformed molecules into myelin. The possibility that an autoradiographic analysis of cholesterol-1,2-H3 incorporation at very short times after injection might shed some light in the solution of that problem led to the present experiment.Cholesterol-1,2-H3 was injected intraperitoneally into 24 tenday old mice. The animals were then sacrificed at 10,20,30,40,60,90,120 and 180 min after the injection and the sciatic nerves were processed for electron microscope autoradiography. To analyze the grain distribution in the autoradiograms of cross and longitudinal sections from each sciatic nerve myelin sheaths were subdivided into three compartments named: outer 1/3, middle 1/3 and inner 1/3 compartments.It was found that twenty min. after the injection of cholesterol -1.2-H3 (Figs. 1 and 2), 55% of the total number of grains (t.n.g) found in myelin were within the outer 1/3 compartment, 9% were within the middle 1/3 and 36% within the inner 1/3 compartment
An Electron Microscopic Study of the Human Gastric Epithelia with Special Reference to the Cardinal Morphological Changes of the Chief Cells Induced by Insulin Stimulus
Authors: Saito Hiroshi , Asano Goro , Aihara Kaoru , Fukushi Katsunari , Yoshida Minoru , Kimura Ken 
Published: June 2020

This short communication is dealt with the ultrastructural changes of the chief cells in insulin stimulus in chronic gastritic condition. The bio gastro-endoscopic biopsy was obtained and pepsin activity of the gastric juice was measured in respective cases. Regular insulin of 0.15U/kg was administrated intra-muscularly and in pre-administration of insulin, 10 minutes, 20 minutes and 30 minutes after administration, biopsied specimens were subjected for electron microscopic studies.In the pre-treated chief cells, extensive development of the cysternal structures of the granular endoplasmic reticulum in basal aspect of the cytoplasm and spherical or oval shaped, light homogeneous zymogen granules in supranuclear region and especially apical aspect of the cytoplasm were featured. Moreover, other type of the chief cells as the one characterized by their fragmented and saccular dilated granular endoplasmic reticulum in basal aspect of the cytoplasm, also exist.
Ultrastructural Changes in Three Different Mammalian Cells Following Ultraviolet Laser Irradiation
Authors: Shankar Narayan K. , Gupta Kailash C. , Okigaki Tohru 
Published: June 2020

The biological effects of short-wave ultraviolet light has generally been described in terms of changes in cell growth or survival rates and production of chromosomal aberrations. Ultrastructural changes following exposure of cells to ultraviolet light, particularly at 265 nm, have not been reported.We have developed a means of irradiating populations of cells grown in vitro to a monochromatic ultraviolet laser beam at a wavelength of 265 nm based on the method of Johnson. The cell types studies were: i) WI-38, a human diploid fibroblast; ii) CMP, a human adenocarcinoma cell line; and iii) Don C-II, a Chinese hamster fibroblast cell strain. The cells were exposed either in situ or in suspension to the ultraviolet laser (UVL) beam. Irradiated cell populations were studied either "immediately" or following growth for 1-8 days after irradiation.Differential sensitivity, as measured by survival rates were observed in the three cell types studied. Pattern of ultrastructural changes were also different in the three cell types.
Application of Electron Optics to Characterization of Particulate Pollutants
Authors: Moran J. B. , Miller J. L. 
Published: June 2020

The Clean Air Act Amendments of 1970 provide the basis for a dramatic change in Federal air quality programs. The Act establishes new standards for motor vehicles and requires EPA to establish national ambient air quality standards, standards of performance for new stationary sources of pollution, and standards for stationary sources emitting hazardous substances. Further, it establishes procedures which allow states to set emission standards for existing sources in order to achieve national ambient air quality standards. The Act also permits the Administrator of EPA to register fuels and fuel additives and to regulate the use of motor vehicle fuels or fuel additives which pose a hazard to public health or welfare.National air quality standards for particulate matter have been established. Asbestos, mercury, and beryllium have been designated as hazardous air pollutants for which Federal emission standards have been proposed.
Dynamic Focusing Techniques for Enhancing SEM Images
Authors: Yew Nelson C. 
Published: June 2020

There are two major areas where Dynamic Focusing techniques can be used to enhance SEM image qualify and micrograph information content. When used in conjunction with the final condenser lens in the electron-optical column, it increases the effective depth of focus associated with an inclined specimen in the SEM. When used with an ultra-high resolution recording cathode ray tube it provides exceptional corner-to-corner sharpness on the micrograph.Most commercial scanning electron microscopes use a tilted specimen positioned close to the final condenser lens with the secondary electron collector system located in the tilting direction to facilitate efficient electron collection. electron beam pivoting through the center of the principle plane of this lens to minimize distortion and off-axis aberration problems. As a result, the final electron beam is truly focused only along a portion of the spherical surface with its center located at the pivoting point.