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  • 1
    Electronic Resource
    Electronic Resource
    Analytic theory of a tapered gyrotron resonator (1981)
    Springer
    International journal of infrared and millimeter waves 2 (1981), S. 629-650 
    Details
    ISSN: 1572-9559
    Keywords: Gyrotron ; Electron Cyclotron Maser ; Microwaves ; Microwave Cavity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An analytic theory has been derived for determining the eigenfrequencies, RF-field distribution and Q of the TEmpq modes of a gyrotron resonator consisting of a circular cylinder joined to a slowly tapered section. Explicit results are obtained for a linear taper. The cavity modes are found to have an RF-field distribution which is useful for prebunching the electron beam and enhancing efficiency. For high Q cavities, the cavity Q depends on axial mode number q as q−2, which is important for mode discrimination. Proper selection of taper length is found to reduce the Q of high q modes, also aiding in mode discrimination. The present approach may be applied to other forms of weakly irregular cavities, such as cavities with nonlinear tapers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01007268
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  • 2
    Electronic Resource
    Electronic Resource
    A 100 kW, 140 GHz pulsed gyrotron (1982)
    Springer
    International journal of infrared and millimeter waves 3 (1982), S. 427-437 
    Details
    ISSN: 1572-9559
    Keywords: Gyrotron ; Electron Cyclotron Maser ; Microwave Tube ; Microwave Oscillator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The design and operation of a 100 kW, 140 GHz pulsed gyrotron are reported. To our knowledge, this is the highest frequency at which high gyrotron output power (〉-100 kW) has been achieved. Results are presented for gyrotron operation in the range of magnetic field from 4 to 7 T, voltage from 23 to 80 kV and current up to 7.5 A. Near a value of magnetic field of 5.4 T, and output power of 100 kW was obtained at 140.4 GHz in single mode operation in the TE031 resonator mode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01007041
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  • 3
    Electronic Resource
    Electronic Resource
    Gut-associated lymphoid tissue (GALT) of the goldfish, Carassius auratus (1986)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 190 (1986), S. 9-26 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The head kidney and spleen are major sites of haemopoiesis in fish; a secondary center is found in loose connective tissue of the intestine. In this study we determined the nature of gut-associated haemopoietic tissue in the goldfish, Carassius auratus, using light and electron microscopy. This tissue is a loose stroma of reticular cells and fibers vascularized by capillaries, venules, and arterioles. The cellular population includes lymphoblasts, small and medium-sized lymphocytes, plasmocytes, macrophages, and various granulocytes. The most abundant granulocyte is the mast cell, whose large granules stain with Alcian blue and toluidine blue. Heterophils are found in the intestinal connective tissue as well as two other granulocytes: one with ovoid granules having dense parallel lamellae and another with granules containing crystalline inclusions. Immature forms of both granulocytes were also noted. Macrophages containing phagocytosed debris were often located close to the epithelium; they were observed forming clusters with lymphocytes. The epithelium contained a number of migrating leucocytes including lymphocytes and lymphoblasts, macrophages, and heterophils. Although many granulocytes were found in the connective tissue, granulopoiesis does not seem to be a major function. Gut-associated haemopoietic tissue in goldfish resembles diffuse lymphoid tissue and may be involved in intestinal immune responses.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051900103
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  • 4
    Electronic Resource
    Electronic Resource
    Variations in mitochondrial ultrastructure and dynamics observed by high resolution scanning electron microscopy (HRSEM) (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 27 (1994), S. 269-277 
    Details
    ISSN: 1059-910X
    Keywords: Cristae ; 3D structure ; Hepatocytes ; Fibroblasts ; Adrenal cortex ; Brown fat ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Rat adrenal cortex was processed for high resolution scanning electron microscopy (HRSEM) to confirm tubular cristae, reported by transmission electron microscopy to be present in cortex mitochondria. Mitochondria in several other tissue and cell types were also observed and their ultrastructure confirmed by using three-dimensional, stereo, high resolution scanning electron microscopy. The mitochondria in rat and human hepatocytes as well as human skin fibroblasts mitochondria proved to be long, up to 46 micrometers and branching, as compared to those in liver which were spherical in shape. Cold adapted brown fat cells were packed with mitochondria, these containing plate or shelf-like cristae. Branched, rat striated muscle mitochondria were observed to curve around contractile protein filament bundles. The muscle mitochondrial cristae were found to be both tubular and plate-like, within the same mitochondrion. The ratio of tubular cristae to plate-like cristae varied considerably between muscle mitochondria. In order to use ultrastructural changes in mitochondria for differential diagnosis, and because 3D reconstruction of mitochondria based on transmission electron microscopy serial sections is severely limited in resolution, it is imperative to first develop a correct understanding of tissue specific, normal mitochondrial ultrastructure based on three-dimensional, HRSEM methods. © 1994 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070270402
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  • 5
    Electronic Resource
    Electronic Resource
    Advantages of digitonin extraction to reveal the intracellular structure of rat glomerular podocytes for high-resolution scanning electron microscopy (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 26 (1993), S. 260-271 
    Details
    ISSN: 1059-910X
    Keywords: Cytoskeleton ; Microtubules ; Intermediate filaments ; Membranous organelles ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Kidneys of anesthetized rats were perfused with digitonin to extract cytosolic proteins of glomerular podocytes so that the remaining intracellular structures could be examined by three-dimensional stereo high-resolution scanning electron microscopy (HRSEM). Cytoskeleton, consisting of microtubules and intermediate filaments, was preserved with each applied concentration of digitonin. High concentrations of digitonin (1.0 mg/ml) produced a corrugated appearance in plasma membranes likely due to the formation of digitonin-cholesterol complexes. At 1.0 mg/ml digitonin, the Golgi complex became vesicularized, and mitochondria were well extracted and their ultrastructure preserved. Lower concentrations of digitonin (0.1 and 0.2 mg/ml) were less disruptive to both the plasma membrane and the Golgi complex. Mitochondria, rough endoplasmic reticulum, coated vesicles, nuclear membrane, and chromatin were well preserved. Extraction with digitonin, at the optimal concentration and perfusion time, simultaneously maintains both the cytoskeleton and membranous organelles inside the cell and provides a method to elucidate the interactions between these two components. Furthermore, digitonin extraction should preserve antigenic sites, thereby allowing the localization of intracellular proteins by backscattered electron imaging of immunogold labels in the scanning electron microscope. © 1993 Wiley-Liss, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070260308
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  • 6
    Electronic Resource
    Electronic Resource
    Chemical extraction of the cytosol using osmium tetroxide for high resolution scanning electron microscopy (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 22 (1992), S. 185-193 
    Details
    ISSN: 1059-910X
    Keywords: Cytosol extraction ; HRSEM ; Fixation ; Intracellular organelles ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Detailed examination of subcellular structures in three dimensions (3D) by high resolution scanning electron microscopy (HRSEM) is now possible due to improvements in the design of the scanning electron microscope and the introduction of methods of specimen preparation using chemical removal of the cytosol and cytoskeleton by dilute osmium tetroxide. Cells which have been fixed, frozen, cleaved, thawed, and subjected to cytosol extraction display intact intracellular structures in 3D including nuclear chromatin, endoplasmic reticulum, mitochondria, and the Golgi complex at a resolution close to that of conventional biological transmission electron microscopy (TEM). Small changes in the 3D structure of subcellular components can be conveniently examined in this way in development, in a variety of physiological processes and in disease. Broad areas of the specimen can be quickly surveyed by HRSEM since sectioning is not required and specimens of comparatively large size (up to 5 mm3) can be placed in the microscope. Extraction of the cytosol with dilute osmium tetroxide (OsO4) exposes subcellular structures in relief, permitting their examination in 3D from several aspects. However, the OsO4 extraction technique is limited, since significant intracellular structures, such as the cytoskeleton, vesicles, and antibody binding sites can be removed or inactivated during the cytosol removal steps. © 1992 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070220207
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  • 7
    Electronic Resource
    Electronic Resource
    The structure of the developing chick retinal pigment epithelium revealed by high resolution scanning electron microscopy (1991)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 18 (1991), S. 231-240 
    Details
    ISSN: 0741-0581
    Keywords: RPE morphology ; Melanosomes ; Plasma membrane ; Chick embryo ; Melanogenesis ; Photoreceptor development ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The retinal pigment epithelium (RPE) in the developing eye of chick embryos has been studied during the early stages of development by high resolution scanning electron microscopy (HRSEM). Specimen preparation techniques which involve removal of the cytoplasmic matrix permitted visualization of organelles and other subcellular structures within RPE cells in detail and in three dimensional (3-D) stereo HRSEM. Using this technique, we were able to examine changes in melanosome structures during development and demonstrate that pigmentation in the RPE was present by day 4 of development. RPE plasma cell membranes showed extensive folding of the apical portion of the membrane closest to the developing neural retina by day 9. Examination of RPE photoreceptor junction revealed photoreceptor inner segments by day 6 and an outer segment by day 9. Mitochondria in the RPE were found to contain tubular cristae only. The ultrastructure in 3-D of the Golgi apparatus, smooth and rough endoplasmic reticulum, lysosomes and nuclear chromatin of the RPE, and Bruch's layer was revealed by the HRSEM method.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060180305
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  • 8
    Electronic Resource
    Electronic Resource
    Tridimensional ultrastructure of perfusion fixed gastrointestinal epithelial cells by high resolution scanning electron microscopy (1991)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 18 (1991), S. 223-230 
    Details
    ISSN: 0741-0581
    Keywords: SEM ; Intestinal morphology ; Intracellular structure ; Mitochondria ; Cell membrane ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Improvements in the design of modern scanning electron microscopes (SEM) and new methods of specimen preparation incorporating chemical removal of the cytosol and cytoskeleton, now make it possible to view cells and their organelles in three dimensions (3D) at high magnification. In this experiment, high resolution SEM (HRSEM) utilizing new methods of tissue preparation was used to study the intracellular structures of the mouse ileum. In addition, in vivo intestinal perfusion was used to further enhance cellular preservation. Using these modifications it was possible to visualize, in 3D, the fine structure of intestinal epithelial cells and intracellular organelles such as the nucleus, mitochondria, endoplasmic reticulum, and Golgi complex, as well as microvilli and cell membrane. Whole mitochondria appeared as irregularly shaped organelles which contained tubular cristae. Plate-like cristae were not observed. The brush border was found to be a closely packed array of cylindrical projections. The extensive folding and structural intricacy of lateral cell membranes between absorptive cells could only be appreciated by viewing this tissue with 3D HRSEM. The use of HRSEM to study 3D ultrastructure of cells and their organelles will improve our understanding of the structure-function relationships in both the healthy and diseased gastrointestinal tract.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060180304
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