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Sample records for electron microscopic study

  1. Electron microscope studies

    SciTech Connect

    Crewe, A.V.; Kapp, O.H.

    1992-07-01

    This is a report covering the research performed in the Crewe laboratory between 1964 and 1992. Because of limitations of space we have provided relatively brief summaries of the major research directions of the facility during these years. A complete bibliography has been included and we have referenced groups of pertinent publications at the beginning of each section. This report summarizes our efforts to develop better electron microscopes and chronicles many of the experimental programs, in materials science and biology, that acted both as a stimulus to better microscope design and also as a testing ground for many instrumental innovations.

  2. Electron microscope studies

    SciTech Connect

    Crewe, A.V.; Kapp, O.H.

    1991-06-01

    This year our laboratory has continued to make progress in the design of electron-optical systems, in the study of structure-function relationships of large multi-subunit proteins, in the development of new image processing software and in achieving a workable sub-angstrom STEM. We present an algebraic approach to the symmetrical Einzel (unipotential) lens wherein we simplify the analysis by specifying a field shape that meets some preferred set of boundary or other conditions and then calculate the fields. In a second study we generalize this approach to study of three element electrostatic lenses of which the symmetrical Einzel lens is a particular form. The purpose is to develop a method for assisting in the design of a lens for a particular purpose. In our biological work we study a stable and functional dodecameric complex of globin chains from the hemoglobin of Lumbricus terrestris. This is a complex lacking the linker'' subunit first imaged in this lab and required for maintenance of the native structure. In addition, we do a complete work-up on the hemoglobin of the marine polychaete Eudistylia vancouverii demonstrating the presence of a hierarchy of globin complexes. We demonstrate stable field-emission in the sub-angstrom STEM and the preliminary alignment of the beam. We continue our exploration of a algorithms for alignment of sequences of protein and DNA. Our computer facilities now include four second generation RISC workstations and we continue to take increasing advantage of the floating-point and graphical performance of these devices.

  3. Electron microscope studies

    NASA Astrophysics Data System (ADS)

    Crewe, A. V.; Kapp, O. H.

    1991-06-01

    This year our laboratory has continued to make progress in the design of electron-optical systems, in the study of structure-function relationships of large multi-subunit proteins, in the development of new image processing software and in achieving a workable sub-angstrom STEM. We present an algebraic approach to the symmetrical Einzel (unipotential) lens wherein we simplify the analysis by specifying a field shape that meets some preferred set of boundary or other conditions and then calculate the fields. In a second study we generalize this approach to study of three element electrostatic lenses of which the symmetrical Einzel lens is a particular form. The purpose is to develop a method for assisting in the design of a lens for a particular purpose. In our biological work we study a stable and functional dodecameric complex of globin chains from the hemoglobin of Lumbricus terrestris. This is a complex lacking the 'linker' subunit first imaged in this lab and required for maintenance of the native structure. In addition, we do a complete work-up on the hemoglobin of the marine polychaete Eudistylia vancouverii, demonstrating the presence of a hierarchy of globin complexes. We demonstrate stable field-emission in the sub-angstrom STEM and the preliminary alignment of the beam. We continue our exploration of a algorithms for alignment of sequences of protein and DNA. Our computer facilities now include four second generation RISC workstations and we continue to take increasing advantage of the floating-point and graphical performance of these devices.

  4. [Electron microscopic study of parchment].

    PubMed

    Rebrikova, N L; Mul'diiarov, P Ia

    1982-12-01

    A study was made of ultrastructure of parchments dating back as far as the XI-XIX centuries (of different degree of preservation) comparatively to parchment manufactured today. It was shown that parchment consists of densely packed bundles of collagenous fibrils with characteristic periods and subperiods. Fibrils are bound with amorphous interfibrillar (apparently protein) material also containing ruteniophilic compounds. In visually changed parchment samples, there were two types of alterations: formation of cracks between the bundles of fibrils and disintegration of fibrils as a result of vital activity of microorganisms. Formation of the cracks appears to favour the penetration of microorganisms into the thickness of parchment thereby contributing to its destruction.

  5. Transmission electron microscope studies of extraterrestrial materials

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.

    1995-01-01

    Transmission Electron Microscopy, X-Ray spectrometry and electron-energy-loss spectroscopy are used to analyse carbon in interplanetary dust particles. Optical micrographs are shown depicting cross sections of the dust particles embedded in sulphur. Selected-area electron diffraction patterns are shown. Transmission Electron Microscope specimens of lunar soil were prepared using two methods: ion-milling and ultramicrotomy. A combination of high resolution TEM imaging and electron diffraction is used to characterize the opaque assemblages. The opaque assemblages analyzed in this study are dominated by ilmenite with lesser rutile and spinel exsolutions, and traces of Fe metal.

  6. Electron Microscope Studies of Cadmium Mercury Telluride

    NASA Astrophysics Data System (ADS)

    Lyster, Martin

    Available from UMI in association with The British Library. Requires signed TDF. Epitaxial layers of Cd_{x }Hg_{(1-x)}Te grown on various substrates by liquid phase epitaxy and metallo-organic vapour phase epitaxy have been studied using transmission and scanning electron microscopy, in a variety of contrast modes. Wavelength-dispersive X-ray microanalysis has been used to study interfaces in epitaxial specimens, and the results are used to derive diffusion coefficients for a range of values of x in Cd_ {x}Hg_{(1-x)} Te. Extensive use has been made of back-scattered electron contrast in the SEM as a means of compositional mapping, and defect structures are imaged by this technique. The back-scattered electron contrast at interfaces has been studied in detail and is modelled using the Monte Carlo approach. The modelling is combined with calculations and practical measurements of the probe size in the SEM instrument used in the work, to arrive at a quantitative explanation of this contrast. The SEM and scintillator detector used allow a spatial resolution of better than 1000A, but it is shown that improvements in this are possible with present technology. Scanning infra-red microscopy (SIRM) and high -resolution transmission electron microscopy (HREM) have been applied to the study of CdTe. SIRM images reveal information about Te precipitation, including particle size and density. HREM images provide results concerning dislocation structures in CdTe. Selected-area diffraction contrast TEM results are presented which illustrate the microstructure of LPE and MOVPE material; and TEM foil preparation techniques are discussed, including the choice of ion species for milling cross-sectional specimens. In view of the results obtained, suggestions are made for future work in this field.

  7. ELECTRON MICROSCOPIC STUDIES OF RENAL DISEASE

    PubMed Central

    Latta, Harrison

    1960-01-01

    The nephrotic syndrome, glomerulonephritis, disseminated lupus erythematosus and the Fanconi syndrome show characteristic changes with electron microscopy. Experimental studies of animals were carried out to determine the significance of such changes by observing reactions that occur under carefully controlled conditions. A lesion with collagen deposition that was found in the centrolobular region of glomeruli sheds new light on the function of this region. This evidence must be considered in developing an understanding of how the production of urine is controlled. Fluid-filled compartments and various bodies associated with the ultrastructure of tubule cells can be produced under conditions which suggest that these structures play a role in tubular resorption. ImagesFigure 1, 2.Figure 3.Figure 4, 5.Figure 6, 7.Figure 8, 9.Figure 10.Figure 11, 12.Figure 13, 14.Figure 15, 16.Figure 17. PMID:13759386

  8. Dental Wear: A Scanning Electron Microscope Study

    PubMed Central

    Levrini, Luca; Di Benedetto, Giulia

    2014-01-01

    Dental wear can be differentiated into different types on the basis of morphological and etiological factors. The present research was carried out on twelve extracted human teeth with dental wear (three teeth showing each type of wear: erosion, attrition, abrasion, and abfraction) studied by scanning electron microscopy (SEM). The study aimed, through analysis of the macro- and micromorphological features of the lesions (considering the enamel, dentin, enamel prisms, dentinal tubules, and pulp), to clarify the different clinical and diagnostic presentations of dental wear and their possible significance. Our results, which confirm current knowledge, provide a complete overview of the distinctive morphology of each lesion type. It is important to identify the type of dental wear lesion in order to recognize the contributing etiological factors and, consequently, identify other more complex, nondental disorders (such as gastroesophageal reflux, eating disorders). It is clear that each type of lesion has a specific morphology and mechanism, and further clinical studies are needed to clarify the etiological processes, particularly those underlying the onset of abfraction. PMID:25548769

  9. Myofibroblasts in fibromatoses. An electron microscopic study.

    PubMed

    Kiryu, H; Tsuneyoshi, M; Enjoji, M

    1985-05-01

    Fifteen cases of fibromatoses were analyzed by electron microscopy, the objective being to compare the incidence and frequency of myofibroblasts in each category. Myofibroblasts were identified in all 15 cases and a considerably large number of these cells appeared in palmar fibromatosis, plantar fibromatosis, and nodular fasciitis. In keloid and cicatricial fibromatosis, however, only a small number of these cells were evident. In seven cases of extra-abdominal desmoid fibromatosis, the frequency of myofibroblasts in the component cells ranged from 10% to 64%, with a mean of 30%. The frequency was high in hypercellular lesions and low in hypocellular lesions, assuming that it would be roughly in parallel to the cellularity of the lesion in extra-abdominal desmoid fibromatosis and in other fibromatoses as well. There appeared to be no particular correlation between the number of myofibroblasts and recurrence of the lesion.

  10. Electron microscope study of Sarcocystis sp

    USGS Publications Warehouse

    Zeve, V.H.; Price, D.L.; Herman, C.M.

    1966-01-01

    Sarcocystis sp. obtained from wild populations of grackles, Quiscalus quiscula (Linn.), were examined to clarify the effect of the parasite on the host. Electron micrographs are presented to show areas of muscle destruction adjacent to the parasite which appear to be mechanically produced by the parasite. The microtubules within the villus-like projections of the cyst suggest that their possible function is absorptive and/or conductive with regard to the production of a toxin or the conveyance of nutritive material to the developing cells. The proposed function of submembranous filaments and their relation to the conoid is discussed. Similarities in the ultrastructure to Toxoplasma and other protozoa tend to negate the relegation of Sarcocystis to the fungi and further emphasize its protozoan nature.

  11. The fragile X: a scanning electron microscope study.

    PubMed Central

    Harrison, C J; Jack, E M; Allen, T D; Harris, R

    1983-01-01

    Scanning electron microscopy (SEM) has been used to study the fragile X chromosome. The fragile site appears as an isochromatid gap in the majority of cases, confirming light microscope (LM) observations. SEM has allowed a more precise location of the fragile site to the Xq27 . 3 region. Images PMID:6684694

  12. Electron microscopic study of an infected Foley catheter.

    PubMed

    Nickel, J C; Gristina, A G; Costerton, J W

    1985-01-01

    A scanning and transmission electron microscopic study was made of material from the surface of a Foley catheter removed from an 87-year-old woman with antibiotic-resistant bacteriuria. A thick, adherent bacterial biofilm was found. The sessile adherent bacteria were surrounded by an extensive exopolysaccharide glycocalyx that appears to be fundamental in the pathogenesis of catheter-associated urinary tract infections and their resistance to systemic antibiotic therapy.

  13. A transmission electron microscopical study of dysplastic naevi.

    PubMed

    Beitner, H; Nakatani, T; Hedblad, M A

    1990-01-01

    In this study those features of naevi that fulfil the clinical and light microscopical criteria of dysplastic naevi have been further examined with transmission electron microscopy. The results have been compared with the structure of normal control skin and compound naevi. In dysplastic naevi most melanosomes were abnormal, with spherical melansomes, an incomplete inner structure and uneven melanin deposit, cigar-shaped melanosomes and macromelanosomes. The intraepidermal border between the nests of dysplastic naevi were uneven and the dysplastic melanocytes extended their cell bodies among surrounding keratinocytes with a tendency to invade the epidermis in an upward direction. These findings will serve as additional criteria for dysplastic naevi.

  14. Pigmentosis tubae, a new entity: light and electron microscopic study

    SciTech Connect

    Herrera, G.A.; Reimann, B.E.; Greenberg, H.L.; Miles, P.A.

    1983-03-01

    The authors noted an unusual finding in the fallopian tubes of a 31-year-old woman who had received external and internal whole pelvis radiotherapy for squamous cell carcinoma of the cervix. Aggregates of macrophages containing pigment, identified in a subepithelial location, were reminiscent of melanosis coli, which is caused by abuse of anthracene-containing laxatives. Electron microscopic examination of the pigment revealed cytoplasmic material with the appearance of lipofuscin, identical to the pigment described in cases of colonic melanosis. After a careful study of possible etiologic agents, it was concluded that the pigment most likely resulted from cellular damage caused by radiotherapy. The authors are not aware of any other reported case of this entity, which will be called pigmentosis tubae.

  15. TEAM Electron Microscope Animation

    SciTech Connect

    2012-01-01

    The TEAM Electron Microscope, a device that enables atomic-scale imaging in 3-D, has a rotating stage that can hold and position samples inside electron microscopes with unprecedented stability, position-control accuracy, and range of motion.The TEAM Stage makes one of the world's most powerful electron microscopes even better, and enables previously impossible experiments.

  16. Achondrogenesis type I: light and electron-microscopic studies.

    PubMed

    Molz, G; Spycher, M A

    1980-06-01

    The light- and electron-microscopic structure of articular and costal cartilage in a case of achondrogenesis type I has been described. The most characteristic ultrastructural change in the chondrocytes was conspicuous dilatation of the rough endoplasmatic reticulum (RER) which contained amorphous electronopaque material. This change in the RER was accompanied by marked hypertrophy of the Golgi apparatus; the matrix was basically unchanged. PMID:6250850

  17. Pulmonary hyalinizing granuloma. Electron microscopic and immunologic studies.

    PubMed

    Guccion, J G; Rohatgi, P K; Saini, N

    1984-04-01

    We present a case of pulmonary hyalinizing granuloma (PHG). On light microscopy, the pulmonary nodular lesions consisted of extracellular, eosinophilic hyaline lamellae. Histochemical stains of the hyaline lamellae for amyloid were focally positive and the diagnosis of amyloidosis was seriously considered; however, on electron microscopic examination, the hyaline lamellae consisted of electrondense, compact, amorphous material quite unlike fibrillar amyloid. Although circulating immune complexes containing IgA were detected in our patient, immunoperoxidase stains did not reveal immunoglobulins in the hyaline lamellae. This case illustrates the value of electron microscopy in differentiating PHG from amyloidosis and supports the hypothesis that PHG represents an exaggerated immune response. PMID:6200274

  18. Electron microscopic studies of mitosis in amebae. I. Amoeba proteus.

    PubMed

    ROTH, L E; OBETZ, S W; DANIELS, E W

    1960-09-01

    Individual organisms of Amoeba proteus have been fixed in buffered osmium tetroxide in either 0.9 per cent NaCl or 0.01 per cent CaCl(2), sectioned, and studied in the electron microscope in interphase and in several stages of mitosis. The helices typical of interphase nuclei do not coexist with condensed chromatin and thus either represent a DNA configuration unique to interphase or are not DNA at all. The membranes of the complex nuclear envelope are present in all stages observed but are discontinuous in metaphase. The inner, thick, honeycomb layer of the nuclear envelope disappears during prophase, reappearing after telophase when nuclear reconstruction is in progress. Nucleoli decrease in size and number during prophase and re-form during telophase in association with the chromatin network. In the early reconstruction nucleus, the nucleolar material forms into thin, sheet-like configurations which are closely associated with small amounts of chromatin and are closely applied to the inner, partially formed layer of the nuclear envelope. It is proposed that nucleolar material is implicated in the formation of the inner layer of the envelope and that there is a configuration of nucleolar material peculiar to this time. The plasmalemma is partially denuded of its fringe-like material during division.

  19. Dynamic-scanning-electron-microscope study of friction and wear

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Buckley, D. H.

    1974-01-01

    A friction and wear apparatus was built into a real time scanning electron microscope (SEM). The apparatus and SEM comprise a system which provides the capability of performing dynamic friction and wear experiments in situ. When the system is used in conjunction with dispersive X-ray analysis, a wide range of information on the wearing process can be obtained. The type of wear and variation with speed, load, and time can be investigated. The source, size, and distribution of wear particles can be determined and metallic transferal observed. Some typical results obtained with aluminum, copper, and iron specimens are given.

  20. Miniaturized Environmental Scanning Electron Microscope for In Situ Planetary Studies

    NASA Technical Reports Server (NTRS)

    Gaskin, Jessica; Abbott, Terry; Medley, Stephanie; Gregory, Don; Thaisen, Kevin; Taylor , Lawrence; Ramsey, Brian; Jerman, Gregory; Sampson, Allen; Harvey, Ralph

    2010-01-01

    The exploration of remote planetary surfaces calls for the advancement of low power, highly-miniaturized instrumentation. Instruments of this nature that are capable of multiple types of analyses will prove to be particularly useful as we prepare for human return to the moon, and as we continue to explore increasingly remote locations in our Solar System. To this end, our group has been developing a miniaturized Environmental-Scanning Electron Microscope (mESEM) capable of remote investigations of mineralogical samples through in-situ topographical and chemical analysis on a fine scale. The functioning of an SEM is well known: an electron beam is focused to nanometer-scale onto a given sample where resulting emissions such as backscattered and secondary electrons, X-rays, and visible light are registered. Raster scanning the primary electron beam across the sample then gives a fine-scale image of the surface topography (texture), crystalline structure and orientation, with accompanying elemental composition. The flexibility in the types of measurements the mESEM is capable of, makes it ideally suited for a variety of applications. The mESEM is appropriate for use on multiple planetary surfaces, and for a variety of mission goals (from science to non-destructive analysis to ISRU). We will identify potential applications and range of potential uses related to planetary exploration. Over the past few of years we have initiated fabrication and testing of a proof-of-concept assembly, consisting of a cold-field-emission electron gun and custom high-voltage power supply, electrostatic electron-beam focusing column, and scanning-imaging electronics plus backscatter detector. Current project status will be discussed. This effort is funded through the NASA Research Opportunities in Space and Earth Sciences - Planetary Instrument Definition and Development Program.

  1. Murine macrophage-lymphocyte interactions: scanning electron microscopic study.

    PubMed Central

    Albrecht, R M; Hinsdill, R D; Sandok, P L; Horowitz, S D

    1978-01-01

    Light and scanning electron microscopic observations revealed murine macrophage-lymphocyte interactions involving the initial contact of peritoneal, spleen, or thymus lymphocytes with peritoneal macrophage processes or microprocesses followed by clustering of lymphocytes over the central nuclear area of the macrophages. Lymphocyte-lymphocyte clustering was not observed in the absence of macrophages. Attachment and subsequent clustering appeared not to require the presence of serum or antigen; the attachment of allogeneic or xenogeneic lymphocytes was comparable to that seen in the syngeneic system, but central clustering of these lymphocytes failed to occur. No attachment or clustering was observed when thymic lymphocytes were cultured with thymus derived fibroblasts rather than with peritoneal macrophages. Lymphocyte attachment to immune, antigen-activated, syngeneic macrophages occurred more rapidly than that to normal unstimulated syngeneic macrophages; however, lymphocytes attached to the "activated" macrophages appeared to be killed by a nonphagocytic mechanism. A similar increase in the rate of lymphocyte attachment to macrophages occurred in the presence of migration inhibitory factor. Subsequent lymphocyte clustering on macrophages was observed in the migration inhibitory factor-stimulated cultures. In addition, lymphocyte-macrophage interactions similar to those in vitro were observed to occur in vivo on intraperitoneally implanted cover slips. Images PMID:101458

  2. [Scanning electron microscope study of chemically disinfected endodontic files].

    PubMed

    Navarro, G; Mateos, M; Navarro, J L; Canalda, C

    1991-01-01

    Forty stainless steel endodontic files were observed at scanning electron microscopy after being subjected to ten disinfection cycles of 10 minutes each one, immersed in different chemical disinfectants. Corrosion was not observed on the surface of the files in circumstances that this study was made.

  3. [Scanning electron microscope study of chemically disinfected endodontic files].

    PubMed

    Navarro, G; Mateos, M; Navarro, J L; Canalda, C

    1991-01-01

    Forty stainless steel endodontic files were observed at scanning electron microscopy after being subjected to ten disinfection cycles of 10 minutes each one, immersed in different chemical disinfectants. Corrosion was not observed on the surface of the files in circumstances that this study was made. PMID:1659857

  4. Electron-microscopic study of Sn-chrisotile asbestos nanocomposite

    NASA Astrophysics Data System (ADS)

    Sorokin, L. M.; Kalmykov, A. E.; Fokin, A. V.; Kumzerov, Yu. A.

    2014-04-01

    Transmission electron microscopy was used to study the structural state of tin in Sn-chrisotile asbestos nanocomposite. It is shown that tin in the nanocomposite forms a system of nanowires, which, in turn, consist of crystallites of different lengths. Various orientational relations between the matrix and crystallites are revealed.

  5. Reflection electron energy-loss spectroscopy and imaging for surface studies in transmission electron microscopes.

    PubMed

    Wang, Z L; Bentley, J

    1992-02-15

    A review is given on the techniques and applications of high-energy reflection electron energy-loss spectroscopy (REELS) and reflection electron microscopy (REM) for surface studies in scanning transmission electron microscopes (STEM) and conventional transmission electron microscopes (TEM). A diffraction method is introduced to identify a surface orientation in the geometry of REM. The surface dielectric response theory is presented and applied for studying alpha-alumina surfaces. Domains of the alpha-alumina (012) surface initially terminated with oxygen can be reduced by an intense electron beam to produce Al metal; the resistance to beam damage of surface domains initially terminated with Al+3 ions is attributed to the screening effect of adsorbed oxygen. Surface energy-loss near-edge structure (ELNES), extended energy-loss fine structure (EXELFS), and microanalysis using REELS are illustrated based on the studies of TiO2 and MgO. Effects of surface resonances (or channeling) on the REELS signal-to-background ratio are described. The REELS detection of a monolayer of oxygen adsorption on diamond (111) surfaces is reported. It is shown that phase contrast REM image content can be significantly increased with the use of a field emission gun (FEG). Phase contrast effects close to the core of a screw dislocation are discussed and the associated Fresnel fringes around a surface step are observed. Finally, an in situ REM experiment is described for studying atomic desorption and diffusion processes on alpha-alumina surfaces at temperatures of 1,300-1,400 degrees C.

  6. Acute hyperuricemic nephropathy in rats. An electron microscopic study.

    PubMed Central

    Waisman, J.; Mwasi, L. M.; Bluestone, R.; Klinenberg, J. R.

    1975-01-01

    Hyperuricemia and uricosuria were induced in rats fed uric acid and oxonic acid. Kidneys then were studied by light and electron microscopy. After 1 day of hyperuricemia, animals had deposits of uric acid and urate crystals within collecting tubules of the renal papillae, and tubular cells were altered. By 10 days, there was an exudative response with further injury to epithelium. Clear spaces within lumens, epithelium, and neutrophils suggested the presence of crystals; however, there was no direct ultrastructural evidence that neutrophils or epithelial cells ingested crystals and suffered injury. Presumably, crystals readily seen in frozen, unfixed tissue were lost during preparation for electron microscopy. Nonetheless, the ultrastructural findings indicated that hyperuricemic nephropathy was initiated in a fashion analogous to urate arthropathy. Urate crystals formed within collecting tubules, epithelial cells were altered, and most likely there was chemotaxis of neutrophils which underwent degranulation and vacuolation followed by lysis freeing any ingested urate. Release of ingested crystals plus precipitation of new crystals both might serve to sustain the nephritis. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 PMID:1190294

  7. An electron microscopic study of bacteriophages from marine waters

    NASA Astrophysics Data System (ADS)

    Frank, Hermann; Moebus, Karlheinz

    1987-12-01

    The morphology of 75 bacteriophage strains isolated from water samples collected in the North Sea or in the northern Atlantic was studied by electron microscopy. Only tailed phages were observed (bradley groups A, B, and C). According to structural similarities, the strains are ascribed to 12 groups, 5 of which comprise types of marine phages not reported before. Four of these 5 groups include phage types that have not been detected from any other source. Among the phages isolated from northern Atlantic water a high incidence was observed of strains the particles of which have long appendages. Certain types of the northern Atlantic phages investigated were derived only from samples collected either east or west of the Azores. This finding agrees with former observations pointing to the existence of different populations of closely related bacteria east and west, respectively, of the northern Mid-Atlantic Ridge.

  8. [Infectious genesis of nephroliths (electron-microscopic study)].

    PubMed

    Didenko, L V; Perepanova, T S; Tolordava, É R; Borovaia, T G; Shevliagina, N V; Égamberdiev, D K; Golovanov, S A; Romanova, Iu M

    2012-01-01

    Scanning electron microscopy and x-ray microstructural analysis were employed in the study of nephroliths from patients suffering from nephrolithiasis. Bacterial biofilms, urease producing microorganisms, alkaline reaction of the urine are basic factors for local urine crystallization, formation of the base of the nephroliths and its rigid fixation to the pelvic mucosa. Mechanic trauma of the pelvic tissues by the concrement results in destruction of the pelvic mucosa epithelium at the site of the nephrolith. Subsequent inflammation in the underlying connective tissue contributes to formation of connective tissue commissures fixing the conrement in the kidney. It is shown that bacteria as a part of a biofilm are capable to persist in nephroliths for a long time. Destruction of the stones during operation or lithotripsy can trigger activation of growth of bacteria integrated in the biofilm and cause septic complications. Preservation of commissures with elements of the destroyed stone after lithotripsy or surgical removal is one of the leading causes of recurrent nephrolithiasis. PMID:23074923

  9. Faecal viruses of dogs--an electron microscope study.

    PubMed

    Finlaison, D S

    1995-09-01

    Faecal samples from 112 dogs both with and without diarrhoea were screened for parvovirus by a haemagglutination titration test and then examined by electron microscopy for the presence of viruses and virus-like particles. On the basis of morphology eight distinct viruses or virus-like particles were identified. Particles identified were coronaviruses, coronavirus-like particles, rotavirus-like particles, papovavirus-like particles, torovirus-like particles, picornavirus-like particles, 27 nm virus-like particles with projections and parvovirus-like particles which did not cause haemagglutination.

  10. Faecal viruses of dogs--an electron microscope study.

    PubMed

    Finlaison, D S

    1995-09-01

    Faecal samples from 112 dogs both with and without diarrhoea were screened for parvovirus by a haemagglutination titration test and then examined by electron microscopy for the presence of viruses and virus-like particles. On the basis of morphology eight distinct viruses or virus-like particles were identified. Particles identified were coronaviruses, coronavirus-like particles, rotavirus-like particles, papovavirus-like particles, torovirus-like particles, picornavirus-like particles, 27 nm virus-like particles with projections and parvovirus-like particles which did not cause haemagglutination. PMID:8545969

  11. Electron microscope phase enhancement

    DOEpatents

    Jin, Jian; Glaeser, Robert M.

    2010-06-15

    A microfabricated electron phase shift element is used for modifying the phase characteristics of an electron beam passing though its center aperture, while not affecting the more divergent portion of an incident beam to selectively provide a ninety-degree phase shift to the unscattered beam in the back focal plan of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. One application of the element is to increase the contrast of an electron microscope for viewing weakly scattering samples while in focus. Typical weakly scattering samples include biological samples such as macromolecules, or perhaps cells. Preliminary experimental images demonstrate that these devices do apply a ninety degree phase shift as expected. Electrostatic calculations have been used to determine that fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size aperture is about 5:1. Calculations are underway to determine the feasibility of aspect smaller aspect ratios of about 3:1 and about 2:1.

  12. AN ELECTRON MICROSCOPE STUDY OF CULTURED RAT SPINAL CORD

    PubMed Central

    Bunge, Richard P.; Bunge, Mary Bartlett; Peterson, Edith R.

    1965-01-01

    Explants prepared from 17- to 18-day fetal rat spinal cord were allowed to mature in culture; such preparations have been shown to differentiate and myelinate in vitro (61) and to be capable of complex bioelectric activity (14–16). At 23, 35, or 76 days, the cultures were fixed (without removal from the coverslip) in buffered OsO4, embedded in Epon, sectioned, and stained for light and electron microscopy. These mature explants generally are composed of several strata of neurons with an overlying zone of neuropil. The remarkable cytological similarity between in vivo and in vitro nervous tissues is established by the following observations. Cells and processes in the central culture mass are generally closely packed together with little intervening space. Neurons exhibit well developed Nissl bodies, elaborate Golgi regions, and subsurface cisternae. Axosomatic and axodendritic synapses, including synaptic junctions between axons and dendritic spines, are present. Typical synaptic vesicles and increased membrane densities are seen at the terminals. Variations in synaptic fine structure (Type 1 and Type 2 synapses of Gray) are visible. Some characteristics of the cultured spinal cord resemble infrequently observed specializations of in vivo central nervous tissue. Neuronal somas may display minute synapse-bearing projections. Occasionally, synaptic vesicles are grouped in a crystal-like array. A variety of glial cells, many apparently at intermediate stages of differentiation, are found throughout the otherwise mature explant. There is ultrastructural evidence of extensive glycogen deposits in some glial processes and scattered glycogen particles in neuronal terminals. This is the first description of the ultrastructure of cultured spinal cord. Where possible, correlation is made between the ultrastructural data and the known physiological properties of these cultures. PMID:14326105

  13. Forensic Scanning Electron Microscope

    NASA Astrophysics Data System (ADS)

    Keeley, R. H.

    1983-03-01

    The scanning electron microscope equipped with an x-ray spectrometer is a versatile instrument which has many uses in the investigation of crime and preparation of scientific evidence for the courts. Major applications include microscopy and analysis of very small fragments of paint, glass and other materials which may link an individual with a scene of crime, identification of firearms residues and examination of questioned documents. Although simultaneous observation and chemical analysis of the sample is the most important feature of the instrument, other modes of operation such as cathodoluminescence spectrometry, backscattered electron imaging and direct x-ray excitation are also exploited. Marks on two bullets or cartridge cases can be compared directly by sequential scanning with a single beam or electronic linkage of two instruments. Particles of primer residue deposited on the skin and clothing when a gun is fired can be collected on adhesive tape and identified by their morphology and elemental composition. It is also possible to differentiate between the primer residues of different types of ammunition. Bullets may be identified from the small fragments left behind as they pass through the body tissues. In the examination of questioned documents the scanning electron microscope is used to establish the order in which two intersecting ink lines were written and to detect traces of chemical markers added to the security inks on official documents.

  14. Embryonic development of rat diaphragm. An electron-microscopic study.

    PubMed

    Angelov, D N; Manolov, S A

    1989-01-01

    Ultrastructural aspects of white Wistar rats diaphragm during part of its embryonic development (from the 13th embryonic day till birth) have been studied. The dominating structures observed in the period of the thirteenth embryonic day (ED 13) are undifferentiated cells, their cytoplasm being poor in organelles but rich in ribosomes. The close examination of these cells reveals that some of them possess a kind of thin filaments near their Golgi zones. At ED 14-15 clusters of myoblasts are readily detected (their cytoplasm containing a lot of glycogen granules and myofibrils, some of them even with Z-line material); contact sites between their cell membranes appear, somewhere forming specialized junctions; in this period the myoblasts start to fuse giving rise to the primary generation of myotubes. At ED 16-17 the quantity of myofilaments and glycogen granules increases alongside with the initiation of a basal-lamina formation; occasionally some oval, undifferentiated cells very similar to those viewed at ED 13 are found. At ED 18-19 the cytoplasm of the myotubes contains a lot of myofibrils and a well-developed endoplasmic reticulum; at some places the adjacent membranes still form deep interdigitations. At the end of the prenatal myogenesis (ED 20-21) most of the muscle cells are close to their mature morphological appearance--the sarcomers are well-organized and some nuclei present a peripheral localization; nevertheless, in this period new generations of myotubes can be also distinguished.

  15. STUDIES ON NUCLEI USING CORRELATED CYTOCHEMICAL, LIGHT, AND ELECTRON MICROSCOPE TECHNIQUES

    PubMed Central

    Moses, Montrose J.

    1956-01-01

    In this paper, a procedure for correlating electron microscope and light microscope cytochemical studies using immediately adjacent serial thin and thick sections has been described and discussed. This technique, combined with the Feulgen reaction for DNA, has been of particular value in framing and answering both general and specific questions about the nucleus. The results may be summarized as follows:— Apparent nuclear homogeneity in the electron microscope is not due to loss of DNA as evidenced by positive Feulgen reactions in such nuclei. Arrangement of Feulgen-positive material in chromosomes, heterochromatin, perinuclear and perinucleolar chromatin, etc., is similar to that customarily observed in the light microscope but this is not necessarily reflected in a cursory survey of the electron image. Careful comparison of light and electron images shows that fine differences in structure are associated with chromatin localization. Primary spermatocyte prophase chromosomes of crayfish have been positively identified by their Feulgen-positive nature. Core-like axial structures in such chromosomes have been observed (9) and are described further. A remarkable feature of spermiogenesis in the crayfish is an elaboration of the nuclear envelope of the spermatid accompanying the formation of what becomes a mass of convoluted membranes in the sperm. In the spermatid, perinuclear chromatin follows outpocketings of the nuclear envelope into the cytoplasm. In the early sperm, on the other hand, although the nuclear envelope is continuous with the system of convoluted membranes, the chromatin is distinct from it and is retained in the nucleus proper by some mechanism independent of the nuclear envelope. None of the above observations was apparent from the electron microscope images alone; they were possible only by virtue of the correlated cytochemical and electron microscope study of adjacent sections. The successful use of other cytochemical tests, such as the PAS

  16. Electron channeling contrast imaging studies of nonpolar nitrides using a scanning electron microscope

    SciTech Connect

    Naresh-Kumar, G.; Kraeusel, S.; Bruckbauer, J.; Edwards, P. R.; Hourahine, B.; Trager-Cowan, C.; Mauder, C.; Heuken, M.; Wang, K. R.; Trampert, A.; Kalisch, H.; Vescan, A.; Giesen, C.; Day, A. P.

    2013-04-08

    Threading dislocations, stacking faults, and associated partial dislocations significantly degrade the optical and electrical properties of materials such as non-polar III-nitride semiconductor thin films. Stacking faults are generally difficult to detect and quantify with existing characterization techniques. We demonstrate the use of electron channeling contrast imaging in the scanning electron microscope to non-destructively reveal basal plane stacking faults terminated by partial dislocations in m-plane GaN and InGaN/GaN multiple quantum well structures grown on {gamma}-LiAlO{sub 2} by metal organic vapor phase epitaxy.

  17. Facilities for in situ ion beam studies in transmission electron microscopes

    SciTech Connect

    Allen, C.W.; Ohnuki, S.; Takahashi, H.

    1993-08-01

    Interfacing an ion accelerator to a transmission electron microscope (TEM) allows the analytical functions of TEM imaging and electron diffraction from very small regions to be employed during ion-irradiation effects studies. At present there are ten such installations in Japan, one in France and one in the USA. General specifications of facilities which are operational in 1993 are summarized, and additional facilities which are planned or being proposed are briefly described.

  18. Transmission electron microscope CCD camera

    DOEpatents

    Downing, Kenneth H.

    1999-01-01

    In order to improve the performance of a CCD camera on a high voltage electron microscope, an electron decelerator is inserted between the microscope column and the CCD. This arrangement optimizes the interaction of the electron beam with the scintillator of the CCD camera while retaining optimization of the microscope optics and of the interaction of the beam with the specimen. Changing the electron beam energy between the specimen and camera allows both to be optimized.

  19. Impermeability of newt cerebral and pial capillaries to exogenous peroxidase. A light and electron microscope study.

    PubMed

    Ciani, F; Del Grande, P; Franceschini, V; Caniato, G; Minelli, G

    1983-01-01

    The permeability of cerebral vessels to exogenous peroxidase was studied in the newt. The reaction product was found only inside the cerebral or pial blood vessels. Electron microscope investigations revealed the presence of reaction product along the luminal area of vessels and in some parts of the intercellular spaces at the level of tight junctions joining endothelial cells. On the basis of the ultrastructural peroxidase localization, the presence of a brain-blood barrier in Triturus is discussed.

  20. Electron microscopic studies on intracellular phage development--history and perspectives.

    PubMed

    Kellenberger, E; Wunderli-Allenspach, H

    1995-01-01

    This review is centered on the applications of thin sections to the study of intracellular precursors of bacteriophage heads. Results obtained with other preparation methods are included in so far as they are essential for the comprehension of the biological problems. This type of work was pioneered with phage T4, which contributed much to today's understanding of morphogenesis and form determination. The T4 story is rich in successes, but also in many fallacies. Due to its large size, T4 is obviously prone to preparation artefacts such as emptying, flattening and others. Many of these artefacts were first encountered in T4. Artefacts are mostly found in lysates, however, experience shows that they are not completely absent from thin sections. This can be explained by the fact that permeability changes induced by fixatives occur. The information gained from T4 was profitably used for the study of other phages. They are included in this review as far as electron microscopic studies played a major role in the elucidation of their morphogenetic pathways. Research on phage assembly pathways and form determination is a beautiful illustration for the power of the integrated approach which combines electron microscopy with biochemistry, genetics and biophysics. As a consequence, we did not restrict ourselves to the review of electron microscopic work but tried to integrate pertinent data which contribute to the understanding of the molecular mechanisms acting in determining the form of supramolecular structures.

  1. Electron microscopic study of soot particulate matter emissions from aircraft turbine engines.

    PubMed

    Liati, Anthi; Brem, Benjamin T; Durdina, Lukas; Vögtli, Melanie; Dasilva, Yadira Arroyo Rojas; Eggenschwiler, Panayotis Dimopoulos; Wang, Jing

    2014-09-16

    The microscopic characteristics of soot particulate matter (PM) in gas turbine exhaust are critical for an accurate assessment of the potential impacts of the aviation industry on the environment and human health. The morphology and internal structure of soot particles emitted from a CFM 56-7B26/3 turbofan engine were analyzed in an electron microscopic study, down to the nanoscale, for ∼ 100%, ∼ 65%, and ∼ 7% static engine thrust as a proxy for takeoff, cruising, and taxiing, respectively. Sampling was performed directly on transmission electron microscopy (TEM) grids with a state-of-the-art sampling system designed for nonvolatile particulate matter. The electron microscopy results reveal that ∼ 100% thrust produces the highest amount of soot, the highest soot particle volume, and the largest and most crystalline primary soot particles with the lowest oxidative reactivity. The opposite is the case for soot produced during taxiing, where primary soot particles are smallest and most reactive and the soot amount and volume are lowest. The microscopic characteristics of cruising condition soot resemble the ones of the ∼ 100% thrust conditions, but they are more moderate. Real time online measurements of number and mass concentration show also a clear correlation with engine thrust level, comparable with the TEM study. The results of the present work, in particular the small size of primary soot particles present in the exhaust (modes of 24, 20, and 13 nm in diameter for ∼ 100%, ∼ 65% and ∼ 7% engine thrust, respectively) could be a concern for human health and the environment and merit further study. This work further emphasizes the significance of the detailed morphological characteristics of soot for assessing environmental impacts. PMID:25180674

  2. Electron microscopic study of soot particulate matter emissions from aircraft turbine engines.

    PubMed

    Liati, Anthi; Brem, Benjamin T; Durdina, Lukas; Vögtli, Melanie; Dasilva, Yadira Arroyo Rojas; Eggenschwiler, Panayotis Dimopoulos; Wang, Jing

    2014-09-16

    The microscopic characteristics of soot particulate matter (PM) in gas turbine exhaust are critical for an accurate assessment of the potential impacts of the aviation industry on the environment and human health. The morphology and internal structure of soot particles emitted from a CFM 56-7B26/3 turbofan engine were analyzed in an electron microscopic study, down to the nanoscale, for ∼ 100%, ∼ 65%, and ∼ 7% static engine thrust as a proxy for takeoff, cruising, and taxiing, respectively. Sampling was performed directly on transmission electron microscopy (TEM) grids with a state-of-the-art sampling system designed for nonvolatile particulate matter. The electron microscopy results reveal that ∼ 100% thrust produces the highest amount of soot, the highest soot particle volume, and the largest and most crystalline primary soot particles with the lowest oxidative reactivity. The opposite is the case for soot produced during taxiing, where primary soot particles are smallest and most reactive and the soot amount and volume are lowest. The microscopic characteristics of cruising condition soot resemble the ones of the ∼ 100% thrust conditions, but they are more moderate. Real time online measurements of number and mass concentration show also a clear correlation with engine thrust level, comparable with the TEM study. The results of the present work, in particular the small size of primary soot particles present in the exhaust (modes of 24, 20, and 13 nm in diameter for ∼ 100%, ∼ 65% and ∼ 7% engine thrust, respectively) could be a concern for human health and the environment and merit further study. This work further emphasizes the significance of the detailed morphological characteristics of soot for assessing environmental impacts.

  3. [The electron microscopic study of tumour-like structures on the vocal cords].

    PubMed

    Il'inskaia, E V; Stepanova, Iu E; Koren', E E; Kosenko, V A

    2015-01-01

    We have undertaken the electron microscopic investigation into peculiarities of six tumour-like structures on the vocal cords. The study has demonstrated changes in the number and distribution patterns of intercellular junctions, keratin and tonofilament contents in epithelial cells, basal membrane structure, and composition of the basic substance in lamina propria. All the examined tumour-like structures contained bacteria an two of them had viral particles in vacuoles of fibroblasts. Moreover, the bacteria were found on the surface of epithelium, between epithelial cells and in the basic substance in lamina propria. Cytoplasm of epithelial cells and fibroblasts not infrequently contained bacteria in the phase of division.

  4. Electron microscopic and optical studies of prism faces of synthetic quartz

    NASA Technical Reports Server (NTRS)

    Buzek, B. C.; Vagh, A. S.

    1977-01-01

    Application of electron and optical microscopic techniques to the study of growth spirals on quartz crystal faces is described. Attention is centered on the centers of the spirals and on screw ledges; overhanging kinks are revealed on one side of the spiral centers. The possibility that these special features may have developed after growth of the crystals went to completion is explored. The conjecture is raised that such structures might result from adsorption of growth-inhibiting impurities at the center of the growth spiral on the quartz habit faces.

  5. PROTEIN SYNTHESIS IN THE VISUAL CELLS OF THE HONEYBEE DRONE AS STUDIED WITH ELECTRON MICROSCOPE RADIOAUTOGRAPHY

    PubMed Central

    Perrelet, Alain

    1972-01-01

    Protein synthesis was studied in the visual cells of an insect (honeybee drone, Apis mellifera) by electron microscope radioautography. After a single injection of tritiated leucine, the radioactivity first appears in the cytoplasm of the visual cell which contains ribosomes. Later, part of this radioactivity migrates to the rhabdome, the visual cell region which is specialized in light absorption. A maximal concentration of radioactivity is reached there 48 hr after the injection of leucine. This pattern of protein synthesis and transport resembles that described in vertebrate visual cells (rods and cones), where newly synthesized proteins have been shown to contribute to the renewal of the photoreceptor membrane. PMID:4656703

  6. Protein synthesis in the visual cells of the honeybee drone as studied with electron microscope radioautography.

    PubMed

    Perrelet, A

    1972-12-01

    Protein synthesis was studied in the visual cells of an insect (honeybee drone, Apis mellifera) by electron microscope radioautography. After a single injection of tritiated leucine, the radioactivity first appears in the cytoplasm of the visual cell which contains ribosomes. Later, part of this radioactivity migrates to the rhabdome, the visual cell region which is specialized in light absorption. A maximal concentration of radioactivity is reached there 48 hr after the injection of leucine. This pattern of protein synthesis and transport resembles that described in vertebrate visual cells (rods and cones), where newly synthesized proteins have been shown to contribute to the renewal of the photoreceptor membrane.

  7. In vitro phagocytosis of exogenous collagen by fibroblasts from the periodontal ligament: an electron microscopic study.

    PubMed Central

    Svoboda, E L; Brunette, D M; Melcher, A H

    1979-01-01

    There have been numerous electron microscopic reports of apparent phagocytosis of collagen by fibroblasts and other cells in vivo. We have developed an in vitro system which, to the best of our knowledge, will permit for the first time the study of regulatory mechanisms governing phagocytosis and digestion of collagen fibres. Cells were cultured from explants of monkey periodontal ligament, subcultured, and grown to confluence in alpha-MEM plus 15% fetal calf serum plus antibiotics. The confluent cells were then cultured together with minced rat tail tendon collagen in alpha-MEM lacking proline, lysine, glycine and fetal calf serum for up to 7 days, after which they were processed for electron microscopy. Intracellular collagen profiles could be seen in cultured cells that were associated with exogenous collagen fibrils as early as 24 hours after addition of the collagen. Through electron microscopic examination of serial sections of the culture, we have demonstrated: (1) that fibroblasts can phagocytose collagen; (2) that the observed intracellular collagen is not the result of aggregation of endogenous synthesized collagen; (3) that it is not possible to base a decision as to whether a collagen fibril has been phagocytosed in whole or in part by the type of vesicle with which it is associated; (4) that cleavage of collagen into small pieces may not be a necessary prelude to its phagocytosis. Images Fig. 1 Fig. 2 Fig. 4 (cont.) Fig. 4 Fig. 6 (cont.) Fig. 6 Fig. 7 Fig. 8 Fig. 9 PMID:108237

  8. Neuroprotective Effects of Memantine in the Retina of Glaucomatous Rats: An Electron Microscopic Study

    PubMed Central

    Celiker, Hande; Yuksel, Nursen; Solakoglu, Seyhun; Karabas, Levent; Aktar, Fadime; Caglar, Yusuf

    2016-01-01

    Purpose: In this experimental study, the effects of systemic memantine administration on the retinal ultrastructure of experimentally induced glaucomatous rats were investigated. Methods: Twenty-four Wistar albino rats were included in this study. Glaucoma was induced by injecting sodium hyaluronate into the anterior chamber of the rats for a period of three weeks. As a control, 8 rats were sham treated (Group C). Glaucoma induced animals were divided into two groups; Group M (n = 8) received a single daily dose of 10 mg/kg memantine, and Group G received the same volume of saline (n = 8), via intraperitoneal route for a period of six weeks, starting with the induction of glaucoma. Then, all rats were sacrificed and the retinas were prepared for electron microscopic examination. Electron microscopic damage findings were graded between 0 and 4 and mean damage scores for each cell or layer was calculated for each group. Statistical comparison was made between group G and group M. Results: Including the photoreceptor cells, marked ultrastructural changes were observed in the retinas of the animals in group G. The ultrastructural changes in group M were modest and there was no significant cell death. Statistical findings indicated these results. Conclusion: Results of the present study suggest that memantine treatment, when started in the early phase of glaucomatous process, may help to preserve the retinal ultrastructure and thus prevent neuronal injury in experimentally induced glaucoma. PMID:27413498

  9. Comparison of the myotoxic effects of levobupivacaine, bupivacaine, and ropivacaine: an electron microscopic study.

    PubMed

    Öz Gergin, Özlem; Yıldız, Karamehmet; Bayram, Adnan; Sencar, Leman; Coşkun, Gülfidan; Yay, Arzu; Biçer, Cihangir; Özdamar, Saim; Polat, Sait

    2015-05-01

    The aim of this study was to investigate the myotoxic effects of bupivacaine, ropivacaine, and levobupivacaine which were applied intramuscularly to rat skeletal muscle. Forty Wistar-Albino rats were divided into four groups. In the study, .5% bupivacaine (Group B), .5% ropivacaine (Group R), .5% levobupivacaine (Group L), or .9% normal saline (Group SF) was applied intramuscularly to the right gastrocnemius muscle of rats. The rats in each group were sacrificed on the second day after injection. Sections of muscle samples were stained with hematoxylin-eosin for light microscopic investigation and prepared for the evaluation of ultrastructural changes in the subcellular level with transmission electron microscopy. All three local anesthetic agents caused qualitatively similar skeletal muscle damage. The most observed muscle damage was in Group B, muscle damage of Group R was less than that of Group B, and the least damage was seen in Group L quantitatively. Electron microscopic examination of each group that caused cellular damage was qualitatively similar. The most subcellular damage was observed in the group receiving bupivacaine, less was seen in the ropivacaine group, and the least was observed in the levobupivacaine group. The results indicated that bupivacaine caused more myotoxic damage than the other two agents in the skeletal muscle of rats and that levobupivacaine caused less myotoxic damage than both bupivacaine and ropivacaine at the cell and tissue levels.

  10. The organization of collagen in cryofractured rabbit articular cartilage: a scanning electron microscopic study.

    PubMed

    Clark, J M

    1985-01-01

    Adult rabbit articular cartilage was prepared for scanning electron microscopy using, in order, glutaraldehyde fixation, enzymatic removal of proteoglycan, dehydration in ethanol, cryofracture in liquid nitrogen, and critical-point drying. Enzymes were effective in fixed material. Fixation, cryofracture, alignment of fracture surfaces with "split lines," and retention of subchondral bone were found to be necessary steps for the preservation of collagen detail. The fibrous framework was found to be similar to that proposed by Benninghoff and favored by more recent phase-contrast microscopic studies. Vertical fibers extending from subchondral bone and a network of tangentially oriented superficial fibrils converge in the transitional zone. No random layer is seen. Pericellular capsules interdigitate with the vertical fibers. When cartilage is prepared in a manner that minimizes tissue damage, scanning electron microscopy provides useful, unique information. PMID:3981292

  11. Mucinous cystadenocarcinoma of the retroperitoneum: a light and electron microscopic study.

    PubMed

    Fujii, S; Konishi, I; Okamura, H; Mori, T

    1986-05-01

    A large, ovarian-type, retroperitoneal cystic tumor existing in the presence of normal ovaries was studied morphologically by light and electron microscopy. The cyst was monolocular, having several papillary nodules which measured 0.2-2.0 cm in diameter, and protruded into the lumen. Histologically, most of the tumor wall was covered by mesothelium-like cells which showed signs of differentiation into either a benign endocervical type mucinous epithelium or a mucinous epithelium of borderline malignancy, particularly around the nodules. The papillary nodules themselves had the histological features of a well-differentiated mucinous adenocarcinoma. These light and electron microscopic features resembled those of ovarian mucinous tumors. Histogenetically, the tumor appeared to be derived from a mesothelial inclusion cyst; some of the mesothelium being transformed by metaplastic change into the endocervical type mucinous epithelium and undergoing further transformation into either the mucinous epithelium of borderline malignancy or the well-differentiated mucinous adenocarcinoma by some unknown factors.

  12. Fibrous architecture of cementodentinal junction in disease: A scanning electron microscopic study

    PubMed Central

    Sudhakar, R; Pratebha, B

    2015-01-01

    Background: The cementodentinal junction (CDJ) forms a biological and structural link between cementum and dentin. This biological link is regarded as a distinct tissue in its own right. Certain important proteins responsible for periodontal regeneration are said to be present in this tissue. Few studies have described the structure and composition of this layer by light and electron microscopy. Scanning electron microscopic studies pertaining to CDJ in health and disease are few and documentation of periodontal pathological changes of CDJ is unclear. In the first phase of our study, the collagenous architecture of CDJ of healthy teeth has been reported. Aim: The objective of this study is to observe and report periodontal pathological changes in the fibrous or collagenous architecture of CDJ of periodontitis-affected teeth and discuss the probable clinical implications of CDJ in disease. Materials and Methods: Twenty periodontitis-affected teeth were collected and processed for observing under a scanning electron microscope. Results: The results are as follows: Increased width of interface at CDJ in periodontitis samples (7.1 μ) compared to that of healthy samples; fewer areas of fiber intermingling at CDJ in periodontitis samples as compared to healthy samples; frequent detachment of cementum from dentin during sodium hydroxide maceration of samples. Conclusion: It may be inferred from results that there is a possibility of a definite weakening of CDJ in periodontally affected root surfaces and we believe that clinical procedures such as scaling and root planning may have a detrimental effect on the cementodentinal attachment of periodontally involved root surfaces. PMID:26980960

  13. In situ transmission electron microscope studies of irradiation-induced and irradiation-enhanced phase changes

    SciTech Connect

    Allen, C.W.

    1991-12-31

    Motivated at least initially by materials needs for nuclear reactor development, extensive irradiation effects studies employing TEMs have been performed for several decades, involving irradiation-induced and irradiation-enhanced, microstructural changes, including phase transformations such as precipitation, dissolution, crystallization, amorphization, and order-disorder phenomena. From the introduction of commercial high voltage electron microscopes (HVEM) in the mid-1960s, studies of electron irradiation effects have constituted a major aspect of HVEM application in materials science. For irradiation effects studies two additional developments have had particularly significant impact: (1) The availability of TEM specimen holders in which specimen temperature can be controlled in the range 10--2200 K; and (2) the interfacing of ion accelerators which allows in situ TEM studies of irradiation effects and the ion beam modification of materials within this broad temperature range. This paper treats several aspects of in situ studies of electron and ion beam-induced and enhanced phase changes, including the current state of in situ ion beam capability internationally, and presents two case studies involving in situ experiments performed in an HVEM to illustrate the dynamics of such an approach in materials research.

  14. In situ transmission electron microscope studies of irradiation-induced and irradiation-enhanced phase changes

    SciTech Connect

    Allen, C.W.

    1991-01-01

    Motivated at least initially by materials needs for nuclear reactor development, extensive irradiation effects studies employing TEMs have been performed for several decades, involving irradiation-induced and irradiation-enhanced, microstructural changes, including phase transformations such as precipitation, dissolution, crystallization, amorphization, and order-disorder phenomena. From the introduction of commercial high voltage electron microscopes (HVEM) in the mid-1960s, studies of electron irradiation effects have constituted a major aspect of HVEM application in materials science. For irradiation effects studies two additional developments have had particularly significant impact: (1) The availability of TEM specimen holders in which specimen temperature can be controlled in the range 10--2200 K; and (2) the interfacing of ion accelerators which allows in situ TEM studies of irradiation effects and the ion beam modification of materials within this broad temperature range. This paper treats several aspects of in situ studies of electron and ion beam-induced and enhanced phase changes, including the current state of in situ ion beam capability internationally, and presents two case studies involving in situ experiments performed in an HVEM to illustrate the dynamics of such an approach in materials research.

  15. Electron Microscope Center Opens at Berkeley.

    ERIC Educational Resources Information Center

    Robinson, Arthur L.

    1981-01-01

    A 1.5-MeV High Voltage Electron Microscope has been installed at the Lawrence Berkeley Laboratory which will help materials scientists and biologists study samples in more true-to-life situations. A 1-MeV Atomic Resolution Microscope will be installed at the same location in two years which will allow scientists to distinguish atoms. (DS)

  16. Scanning Electron Microscopic Studies of the Pecten Oculi in the Quail (Coturnix coturnix japonica)

    PubMed Central

    Pourlis, Aris F.

    2013-01-01

    The main purpose of this study is to extend the microscopic investigations of the pecten oculi in the quail in order to add some information on the unresolved functional anatomy of this unique avian organ. The pecten oculi of the quail was studied by scanning electron microscopy. Eighteen- to-twenty two highly vascularised accordion-like folds were joined apically by a heavily pigmented bridge of tissue, which holds the pecten in a fanlike shape, widest at the base. The structure of the double layered limiting membrane was recorded. The presence of hyalocytes with macrophage-like appearance was illustrated. It is assumed that the pecten oculi of the quail resembles that of the chicken. Illustrated morphological features of this species may add information on the active physiological role of the pecten. But still, the functional significance of this organ is a matter of controversies. PMID:24198967

  17. Light- and electron-microscopic studies of transplanted human dystrophic muscles to nude mice.

    PubMed

    Wakayama, Y; Ohbu, S

    1982-07-01

    Light-microscopic study of muscles from 8 patients with Duchenne muscular dystrophy (DMD) and 9 control cases transplanted into nude mice showed the formation of cross-striations and peripheral nuclei in regenerating muscle fibers of both DMD and control grafts up to 4 weeks. Quantitative study of the diameter of myotubes and myoblasts in grafted muscles showed that the group mean diameters of DMD myotubes and myoblasts were 13.4 +/- 0.8 (SE) micrometers, 15.6 +/- 0.7 micrometers, 17.1 +/- 0.9 micrometers and 16.2 +/- 1.0 micrometers after 1, 2, 3 and 4 weeks of transplantation, respectively, whereas those of control myotubes and myoblasts were 14.9 +/- 0.6 (SE) micrometers, 19.9 +/- 0.5 micrometers, 21.3 +/- 0.7 micrometers and 20.7 +/- 0.7 micrometers after the same intervals. The group mean diameters of the DMD regenerating myotubes and myoblasts were significantly smaller than those of control myotubes and myoblasts at 2 (P less than 0.001), 3 (P less than 0.005) and 4 (P less than 0.005) weeks after transplantation. Electron-microscopic findings of DMD muscle grafts were morphologically similar to those seen in control muscle grafts at all stages of this experiment.

  18. Scanning electron microscope study of Torulopsis ethanolitolerans prepared by glutaraldehyde--thiosemicarbohydrazide procedure.

    PubMed

    Hulínská, D; Mohelská, H; Adámek, L; Rut, M

    1989-01-01

    Torulopsis ethanolitolerans subject to both the sparing and coarse heat treatment were studied in the scanning electron microscope. The reduction of adhesivity, increased permeability and higher rigidity of the yeast wall was achieved by an original glutaraldehyde-paraformaldehyde fixation, low osmolarity in vacuo and subsequent thiosemicarbohydrazide incubation, followed by addition of metal salt. The impregnation of the metal throughout the specimen due to the reaction of the thiosemicarbohydrazide with glutaraldehyde allowed viewing of small or intricate surface details of the yeast. Structural differences of the yeast processed by sparing and coarse heat treatment were shown to be better from the thiosemicarbohydrazide incubated samples compared to those that were prepared with osmium tetroxide. PMID:2509313

  19. An analytical electron microscope study of airborne industrial particles in Sosnowiec, Poland

    NASA Astrophysics Data System (ADS)

    Rietmeijer, Frans J. M.; Janeczek, Janusz

    The types and the relative amounts of airborne particles in the city of Sosnowiec (Poland) during 21-22 June, 1994 were identified by analytical electron microscope analyses. They are mostly aspherical angular Al-bearing silica particles (0.1-5.15 μm) and clusters thereof. Carbonaceous particles form sheets of soluble volatile-rich materials (0.3-33.9 μm) and rare soot. Numerous nanometer-sized Al-bearing silica grains and salt minerals are associated with the larger particles. They resulted from inefficient combustion of low-grade coals by the local industries whereby the silica particles are coal impurities that survived combustion. The total particle emission was constant during a 24 h period but silica shards dominated the nighttime emission while carbonaceous particles abounded during the daytime. This study showed that tropospheric particles in regions dominated by inefficient coal combustion are fundamentally different from typical coal fly ash spheres.

  20. Synaptic endfeet in the 'acoustic nerve nucleus' of the rat. An electron microscopic study.

    PubMed Central

    Alvarez-Bolado, G; Merchán, J

    1988-01-01

    The medial portion of the cochlear nerve of the rat contains astrocytes, oligodendrocytes and neurons. These neurons form what has been called the 'acoustic nerve nucleus'. This nucleus has been studied here at the electron microscopic level. Its neurons are large and round, showing an eccentric nucleus, fibrillary bodies and rough endoplasmic reticulum which is not arranged in stacks. The somata and dendrites receive synaptic endfeet which can be classified into three groups according to vesicle size and shape. In general, the ultrastructural characteristics of these cells are similar to those of bushy cells as reported by other authors. The 'acoustic nerve nucleus' can be considered to be the most peripheral part of the anterior ventral cochlear nucleus. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 PMID:3248967

  1. Scanning electron microscope studies of bone samples: Influence of simulated microgravity

    NASA Astrophysics Data System (ADS)

    Mehta, Rahul; Chowdhury, Parimal; Ali, Nawab

    2007-08-01

    A scanning electron microscope (SEM) with backscatter and secondary electron emission detectors plus a Si(Li) detector for photon yield measurements was used to study bone samples from skull and leg of mice and rats. These animals were either suspended by their tail to induce simulated microgravity, characterized as hind-limb suspension (HLS) or not suspended (control). Analyses of the SEM images and energy dispersive spectrometer (EDS) spectra using Si(Li) detector indicate variation in the lattice structures, and in intensities of the characteristics X-rays, produced from the exposed bone surface due to its interaction with the electron beam. Using Flame software, the X-ray spectra were analyzed and normalized ratios of the elements determined. The elemental analysis indicated a variation in the density of calcium, potassium, and oxygen near the knee joints and near the sutures in the skull bones. The comparison of simulated microgravity subjected samples of the rat skull bones with that of the control samples revealed that in the suture region there was a large increase in the ratio of calcium, and to some degree for phosphorus, suggesting simulated microgravity affects distribution of these elements. Elemental composition for control samples with depth (within the cross section of the leg bones) revealed decrease of oxygen and increase of calcium in the first millimeter of the bone depth after which the relative percentage of elements stayed constant.

  2. Electron microscope studies. Progress report, 1 July 1964--1 June 1992

    SciTech Connect

    Crewe, A.V.; Kapp, O.H.

    1992-07-01

    This is a report covering the research performed in the Crewe laboratory between 1964 and 1992. Because of limitations of space we have provided relatively brief summaries of the major research directions of the facility during these years. A complete bibliography has been included and we have referenced groups of pertinent publications at the beginning of each section. This report summarizes our efforts to develop better electron microscopes and chronicles many of the experimental programs, in materials science and biology, that acted both as a stimulus to better microscope design and also as a testing ground for many instrumental innovations.

  3. Electron microscopic examination of effects of bogma raki and walnut on cochlea: an experimental study.

    PubMed

    Cevik, C; Ozler, G S; Arli, C; Tatar, I; Sargon, M F; Zeren, C; Yonden, Z; Akoglu, E

    2015-03-01

    Illegal alcohol beverages known as bogma raki in our country are consumed widely in our region. The studies investigating the relationship between alcohol consumption and hearing ability report different results. In this study, we aimed to investigate the toxic effects of bogma raki that contains neurotoxic substances on cochlea by electron microscopy. To the best of our knowledge, this study is the first in the literature. A total of 48 Wistar male albino rats (aged 12-16 weeks and weighing 200-240 g) were used in the study. The rats were divided into 4 groups with 12 animals in each group. The groups include control, bogma raki, walnut, and walnut + bogma raki groups. Bogma raki (30% v/v, 9.2 ml kg(-1) day(-1)) is added to drinking water of rats in bogma raki group (n = 12) for 4 weeks. Walnut group rats (n = 12) are fed with standard rat food and walnut without limitation (10 g kg(-1) day(-1)). Bogma raki + walnut group rats (n = 12) are fed with standard rat food and walnut and bogma raki is added to drinking water. The cochleas were dissected and removed en bloc and examined by electron microscopy. Perineuronal oedema around neurons of spiral ganglion and hairy cells of organ of Corti were present in the bogma raki group, walnut group and bogma raki + walnut group under electron microscopic examination. Comparing these three groups, there were no differences in the ultrastructural pathological changes. In the ultrastructural examination of the myelinated axons forming cochlear nerve, no ultrastructural pathology was detected in all the groups.

  4. Transmission electron microscopic study of pyrochlore to defect-fluorite transition in rare-earth pyrohafnates

    SciTech Connect

    Karthik, Chinnathambi; Anderson, Thomas J.; Gout, Delphine; Ubic, Rick

    2012-10-15

    A structural transition in rare earth pyrohafnates, Ln{sub 2}Hf{sub 2}O{sub 7} (Ln=Y, La, Pr, Nd, Tb, Dy, Yb and Lu), has been identified. Neutron diffraction showed that the structure transforms from well-ordered pyrochloric to fully fluoritic through the lanthanide series from La to Lu with a corresponding increase in the position parameter x of the 48f (Fd3{sup Macron }m) oxygen site from 0.330 to 0.375. As evidenced by the selected area electron diffraction, La{sub 2}Hf{sub 2}O{sub 7}, Pr{sub 2}Hf{sub 2}O{sub 7} and Nd{sub 2}Hf{sub 2}O{sub 7} exhibited a well-ordered pyrocholoric structure with the presence of intense superlattice spots, which became weak and diffuse (in Dy{sub 2}Hf{sub 2}O{sub 7} and Tb{sub 2}Hf{sub 2}O{sub 7}) before disappearing completely as the series progressed towards the Lu end. High resolution electron microscopic studies showed the breakdown of the pyrochlore ordering in the form of antiphase domains resulting in diffused smoke-like superlattice spots in the case of Dy{sub 2}Hf{sub 2}O{sub 7} and Tb{sub 2}Hf{sub 2}O{sub 7}. - Graphical abstract: Transmission electron microscopic studies showed the ordered pyrochlore to defect fluorite transition in rare-earth pyrohafnates to occur via the formation of anti-phase domains to start with. Highlights: Black-Right-Pointing-Pointer Pyrochlore to fluorite structural transition in rare earth pyrohafnates. Black-Right-Pointing-Pointer La{sub 2}Hf{sub 2}O{sub 7}, Pr{sub 2}Hf{sub 2}O{sub 7} and Nd{sub 2}Hf{sub 2}O{sub 7} showed well ordered pyrochlore structure. Black-Right-Pointing-Pointer Short range ordering in Dy{sub 2}Hf{sub 2}O{sub 7} and Tb{sub 2}Hf{sub 2}O{sub 7}. Black-Right-Pointing-Pointer Break down of pyrochlore ordering due to antiphase boundaries. Black-Right-Pointing-Pointer Rest of the series showed fluoritic structure.

  5. Carbon nanotube electron sources for electron microscopes

    SciTech Connect

    De Jonge, Niels

    2009-01-01

    Electron sources were made from individual multi-walled carbon nanotubes with closed caps and thoroughly cleaned surfaces. Nanotubes from both chemical vapor deposition growth and arc discharge growth were investigated. These emitters provide a highly stable emission current up to a threshold current of a few microamperes. At too large currents several processes take place such as splitting, breaking and cap closing. The emission process is field emission for a workfunction of 5 eV. The electron optical per-formance is highly beneficial for their use as high-brightness point sources in electron microscopes and advantageous with respect to state-of-the-art electron sources. The life-time is at least two years. We have tested the source successfully in a scanning electron microscope.

  6. Integrity of the interface between denture base and soft liner: a scanning electron microscopic study.

    PubMed

    Muralidhar, G; Satish Babu, C L; Shetty, Shilpa

    2012-06-01

    Aims and objectives of the study was to study the integrity of the interface between the denture base and the soft liner when the thickness of the soft liner was 0.5, 1.0 and 2.0 mm, and to study the integrity of the soft liner and denture base interface as influenced by aging process. 80 rectangular based specimens were fabricated using heat cured acrylic resin. The heat cured component of the specimen was fabricated from stainless steel template form by compression molding technique. Different thickness of silicone soft layer component was added to heat cured acrylic resin component of the specimen following the manufacturer's instructions to fabricate the group A, group B, group C and group D specimens. All the specimens were subjected to the same finishing and polishing procedures. The group A specimens was immediately scanned in scanning electron microscope after processing. A thermo statically controlled artificial saliva bath designed to maintain the temperature between 38 ± 4°C was used to simulate the oral condition and to age the group B, group C and group D specimens for 3 months after which they were subjected to scanning under a scanning electron microscope. All the aged specimens demonstrated two types of failures namely adhesive which occurred along the bond interface between the soft liner and the acrylic resin and adhesive and cohesive type of failure which occurred not only at the interface but also within the soft liner material itself. When the data was subjected to ANOVA, the group A specimens showed statistical significance with group B (P = 0.006), group C (P = 0.007) and group D specimens (P = 0.004), the level of significance being (P < 0.05). However, there was no statistical significance between group B and C (P = 0.98), group C and D specimens (P = 0.52), group B and D specimens (P = 0.70), the level of significance being (P < 0.05). Based on the results, statistical analysis of the results and within the

  7. Integrity of the interface between denture base and soft liner: a scanning electron microscopic study.

    PubMed

    Muralidhar, G; Satish Babu, C L; Shetty, Shilpa

    2012-06-01

    Aims and objectives of the study was to study the integrity of the interface between the denture base and the soft liner when the thickness of the soft liner was 0.5, 1.0 and 2.0 mm, and to study the integrity of the soft liner and denture base interface as influenced by aging process. 80 rectangular based specimens were fabricated using heat cured acrylic resin. The heat cured component of the specimen was fabricated from stainless steel template form by compression molding technique. Different thickness of silicone soft layer component was added to heat cured acrylic resin component of the specimen following the manufacturer's instructions to fabricate the group A, group B, group C and group D specimens. All the specimens were subjected to the same finishing and polishing procedures. The group A specimens was immediately scanned in scanning electron microscope after processing. A thermo statically controlled artificial saliva bath designed to maintain the temperature between 38 ± 4°C was used to simulate the oral condition and to age the group B, group C and group D specimens for 3 months after which they were subjected to scanning under a scanning electron microscope. All the aged specimens demonstrated two types of failures namely adhesive which occurred along the bond interface between the soft liner and the acrylic resin and adhesive and cohesive type of failure which occurred not only at the interface but also within the soft liner material itself. When the data was subjected to ANOVA, the group A specimens showed statistical significance with group B (P = 0.006), group C (P = 0.007) and group D specimens (P = 0.004), the level of significance being (P < 0.05). However, there was no statistical significance between group B and C (P = 0.98), group C and D specimens (P = 0.52), group B and D specimens (P = 0.70), the level of significance being (P < 0.05). Based on the results, statistical analysis of the results and within the

  8. [Electron microscopic and immunological study of influenza virus interaction with murine peritoneal microphages].

    PubMed

    Kirillova, F M; Berdinskikh, M S; Kiseleva, A S; Avakian, A A; Kosiakov, P N

    1980-01-01

    Electron microscopic and immunological investigations of influenza virus HONI interactions with peritoneal macrophages of intact and immune mice were carried out. Both intact and immune macrophages exert phagocytosis and disintegration of virions in phagolysosomes as early as 10 and 30 min after the end of adsorption. This process is most active with eosinophils, less in neutrophils and the least in basophils. Titration of the infectious virus in chick embryos showed that immune macrophages contained considerably less virus than the intact ones.

  9. [Intracytoplasmic lumina of benign and malignant breast diseases--a light and electron microscopic study].

    PubMed

    Gu, C M

    1990-07-01

    Intracytoplasmic lumina (ICLs) of 70 cases with breast carcinoma and 29 cases with benign breast diseases were observed by light and electron microscopy. ICLs were morphologically divided into two types. Type A was characterized by the presence of secretory materials stained with eosin in the lumen and Type B by the cytoplasmic vacuoles under light microscope. Electron microscopic observation on Type A ICLs showed numerous filiform microvilli projecting towards the lumen and various amounts of secretory materials in the lumen. Type B of ICLs only had scanty and short microvilli and rarely secretory materials in the lumen. The results indicated that: 1. The frequency of ICLs in breast cancer was significantly higher than that in benign breast disease (P less than 0.01). 2. The frequency of ICLs in breast cancer showed strong negative correlation with its histological grades but not with its histological types. 3. ICLs had similar frequency under both light and electron microscopes. As a relatively specific structure in breast carcinoma cells, ICLs may be helpful in the diagnosis of breast carcinoma and establishment of the breast origin for metastatic carcinoma. PMID:2176965

  10. Scanning electron microscopic study of laser-induced morphologic changes of a coated enamel surface

    SciTech Connect

    Hess, J.A. )

    1990-01-01

    A low-energy Nd:YAG laser was used to irradiate extracted human teeth coated with a black energy-absorbent laser initiator in a study to determine the extent of the morphologic changes produced in the enamel surface. The laser initiator was applied to a cleaned enamel surface and irradiated at an energy output of 30 mJ or 75 mJ. Both energy levels produced morphologic changes of the surface. There was a sharp line of demarcation between the coated, irradiated area and the surrounding noncoated enamel surface. The scanning electron microscope view at the lower energy level showed that the surface had melted and reformed with numerous small, bubble-like inclusions. The 75 mJ energy level showed individual impact craters with shallow centers and raised edges containing numerous pores and large, bubble-like inclusions. Etching is a dental procedure in which an acid is normally used to remove a thin outer layer of the tooth structure. This is necessary to create a roughened, irregular surface in order to provide mechanical retention for dental restorative materials. The changes produced by the laser in this study suggest a simple, effective, and controlled method of etching the enamel surface of a tooth by altering its surface characteristics.

  11. A study on the conditioning effects of natural shampoos using the scanning electron microscope.

    PubMed

    Bellare, J; Iyer, R; Mainkar, A R; Jolly, C I

    2001-06-01

    The scanning electron microscope (SEM) was successfully used to study the effects of toiletry treatment with shampoo on the microstructure of hair. This paper describes the use of SEM for comparing the conditioning effects of herbal shampoos. Commercially available herbal shampoos are not completely natural, but contain herbal extracts in a synthetic detergent base, along with other chemical additives. Completely natural shampoos were formulated in the laboratory and their conditioning effects were evaluated by comparing with a commercially available herbal shampoo. The micrographs were studied quantitatively using 'Image Analyser Software' and the extent to which the hair scales were uplifted was measured. The results obtained from the quantitative comparison were in agreement with those obtained from other tests, such as protein loss determination. The damage caused to the hair due to sodium lauryl sulphate was visible in the micrographs. The laboratory formulations were found to be better than the commercially available product. Thus, quantitative measurements from SEM micrographs are a valuable tool to compare the conditioning effects of hair care products.

  12. Scanning electron microscopic study of human neuroblastoma cells affected with Naegleria fowleri Thai strains.

    PubMed

    Tiewcharoen, Supathra; Rabablert, Jundee; Chetanachan, Pruksawan; Junnu, Virach; Worawirounwong, Dusit; Malainual, Nat

    2008-10-01

    In order to understand the pathogenesis of Naegleria fowleri in primary amoebic meningoencephalitis, the human neuroblastoma (SK-N-MC) and African green monkey kidney (Vero) cells were studied in vitro. Amoeba suspension in cell-culture medium was added to the confluent monolayer of SK-N-MC and Vero cells. The cytopathic activity of N. fowleri trophozoites in co-culture system was elucidated by scanning electron microscope at 3, 6, 9, 12, and 24 h. Two strains of N. fowleri displayed well-organized vigorous pseudopods in Nelson's medium at 37 degrees C. In co-culture, the target monolayer cells were damaged by two mechanisms, phagocytosis by vigorous pseudopods and engulfment by sucker-like apparatus. N. fowleri trophozoites produced amoebostomes only in co-culture with SK-N-MC cells. In contrast, we could not find such apparatus in the co-culture with Vero cells. The complete destruction time (100%) at 1:1 amoeba/cells ratio of SK-N-MC cells (1 day) was shorter than the Vero cells (12 days). In conclusion, SK-N-MC cells were confirmed to be a target model for studying neuropathogenesis of primary amoebic meningoencephalitis.

  13. Spectral Interferometry with Electron Microscopes.

    PubMed

    Talebi, Nahid

    2016-01-01

    Interference patterns are not only a defining characteristic of waves, but also have several applications; characterization of coherent processes and holography. Spatial holography with electron waves, has paved the way towards space-resolved characterization of magnetic domains and electrostatic potentials with angstrom spatial resolution. Another impetus in electron microscopy has been introduced by ultrafast electron microscopy which uses pulses of sub-picosecond durations for probing a laser induced excitation of the sample. However, attosecond temporal resolution has not yet been reported, merely due to the statistical distribution of arrival times of electrons at the sample, with respect to the laser time reference. This is however, the very time resolution which will be needed for performing time-frequency analysis. These difficulties are addressed here by proposing a new methodology to improve the synchronization between electron and optical excitations through introducing an efficient electron-driven photon source. We use focused transition radiation of the electron as a pump for the sample. Due to the nature of transition radiation, the process is coherent. This technique allows us to perform spectral interferometry with electron microscopes, with applications in retrieving the phase of electron-induced polarizations and reconstructing dynamics of the induced vector potential. PMID:27649932

  14. Spectral Interferometry with Electron Microscopes

    PubMed Central

    Talebi, Nahid

    2016-01-01

    Interference patterns are not only a defining characteristic of waves, but also have several applications; characterization of coherent processes and holography. Spatial holography with electron waves, has paved the way towards space-resolved characterization of magnetic domains and electrostatic potentials with angstrom spatial resolution. Another impetus in electron microscopy has been introduced by ultrafast electron microscopy which uses pulses of sub-picosecond durations for probing a laser induced excitation of the sample. However, attosecond temporal resolution has not yet been reported, merely due to the statistical distribution of arrival times of electrons at the sample, with respect to the laser time reference. This is however, the very time resolution which will be needed for performing time-frequency analysis. These difficulties are addressed here by proposing a new methodology to improve the synchronization between electron and optical excitations through introducing an efficient electron-driven photon source. We use focused transition radiation of the electron as a pump for the sample. Due to the nature of transition radiation, the process is coherent. This technique allows us to perform spectral interferometry with electron microscopes, with applications in retrieving the phase of electron-induced polarizations and reconstructing dynamics of the induced vector potential. PMID:27649932

  15. Spectral Interferometry with Electron Microscopes.

    PubMed

    Talebi, Nahid

    2016-01-01

    Interference patterns are not only a defining characteristic of waves, but also have several applications; characterization of coherent processes and holography. Spatial holography with electron waves, has paved the way towards space-resolved characterization of magnetic domains and electrostatic potentials with angstrom spatial resolution. Another impetus in electron microscopy has been introduced by ultrafast electron microscopy which uses pulses of sub-picosecond durations for probing a laser induced excitation of the sample. However, attosecond temporal resolution has not yet been reported, merely due to the statistical distribution of arrival times of electrons at the sample, with respect to the laser time reference. This is however, the very time resolution which will be needed for performing time-frequency analysis. These difficulties are addressed here by proposing a new methodology to improve the synchronization between electron and optical excitations through introducing an efficient electron-driven photon source. We use focused transition radiation of the electron as a pump for the sample. Due to the nature of transition radiation, the process is coherent. This technique allows us to perform spectral interferometry with electron microscopes, with applications in retrieving the phase of electron-induced polarizations and reconstructing dynamics of the induced vector potential.

  16. Evaluation of two different root-end cavity preparation techniques: A scanning electron microscope study

    PubMed Central

    Aydemir, Seda; Cimilli, Hale; Hazar Yoruç, Afife Binnaz; Kartal, Nevin

    2013-01-01

    Objective: In this study, we aimed to evaluate and compare the dentinal walls of root-end cavities for the presence of cracks after cavity preparation using US retrotips and Er: YAG laser. Materials and Methods: Fifty single-rooted teeth were prepared by Protaper NiTi rotary system and obturated by lateral condensation. Three milimeters of root-end was resected. Twenty teeth were prepared with US retrotip (Group 1), 20 teeth with Er: YAG laser (Group 2), and 10 teeth without retropreparation (control group). The root-end surfaces were examined under a scanning electron microscope (SEM). Then the cracks of the resected root surfaces were evaluated on microphotographs. Results: No statistically significant difference was detected between US Group and Laser Group for complete, incomplete, intradentinal, and total number of cracks (P = 0.47, P = 0.80, P = 0.69, P = 0.869, respectively). Conclusion: Statistical analysis revealed no significant effect of retropreparation technique on the development of apical cracks (P > 0.05). PMID:24883024

  17. Orthodontic Cements and Demineralization: An In Vitro Comparative Scanning Electron Microscope Study

    PubMed Central

    Prabhavathi, V; Jacob, Josy; Kiran, M Shashi; Ramakrishnan, Murugesan; Sethi, Esha; Krishnan, C S

    2015-01-01

    Background: Comparison of the demineralization potential of four luting cements, i.e. zinc phosphate, conventional glass ionomer cement (GIC), resin-modified GIC and acid modified composite resin. Materials and Methods: This study was conducted on 75 extracted premolar teeth, which were grouped into five, each group containing 15 teeth. Groups were non-banded control, teeth cemented with the above-mentioned cements. These were incubated at 37°C for 30 days in sealable plastic containers, after which the teeth were debanded, cleaned and placed in acid gelatin solution at 37°C for 4 weeks to simulate the cariogenic solution. Then, the teeth were sectioned and examined under scanning electron microscope. The depth of the carious lesions was measured using image analysis with Digimizer software. Results: The depth of the carious lesions was maximum with non-banded group, followed by zinc phosphate, acid modified composite resin, resin-modified GIC and conventional GIC. Conclusions: Among the four orthodontic banding cements compared, the enamel demineralization potential is least with conventional GIC, followed by resin-modified GIC, acid modified composite resin and zinc phosphate. PMID:25859103

  18. Copper thick film sintering studies in an environmental scanning electron microscope.

    PubMed

    Link, L F; Gerristead, W R; Tamhankar, S

    1993-08-01

    The significance of the ElectroScan environmental scanning electron microscope (ESEM) as a processing tool for studying dynamic morphological changes under controlled temperature/atmosphere conditions was evaluated. The ability to observe dynamic processes in situ, which cannot be achieved by other means, is critical to understanding microstructural formation. Processing of printed copper thick films on ceramics was used as a test case, wherein morphological changes associated with the steps of organic binder removal and sintering of copper particles were observed/examined in real time. Good agreement was seen between microstructures obtained in the ESM and those achieved in a belt furnace when similar process variables were used. When processed in atmospheres which were proven to induce sintering in a conventional belt furnace, sintering was evident in both cases, and the microstructural changes were documented on video-tapes in real time. Determination of critical event temperatures was achieved--that is, binder burnout occurring between 270 degrees and 350 degrees C, onset of oxidation at 520 degrees C, and sintering starting at 770 degrees C. It was thus verified that the microstructural changes during the copper thick film sintering process can be observed in situ using an ESEM.

  19. Electron microscopic study on interfacial characterization of electroless Ni W P plating on aluminium alloy

    NASA Astrophysics Data System (ADS)

    Hu, Yong-jun; Xiong, Ling; Meng, Ji-long

    2007-03-01

    The interface between electroless plating Ni-W-P deposit and aluminium alloy (Al) matrix at different temperature heated for 1 h was studied using transmission electron microscope. The results show that the interface between as-deposited Ni-W-P deposit and Al matrix is clear. There are no crack and cavity. The bonding of Ni-W-P deposit and Al matrix is in good condition. The Ni-W-P plating is nanocrystalline phase (5-6 nm) in diameter. After being heated at 200 °C for 1 h, the interface of Ni-W-P deposit and Al matrix is clear, without the appearance of the diffusion layer. There exist a diffusion layer and educts of intermetallic compounds of nickle and aluminium such as Al 3Ni, Al 3Ni 2, NiAl, Ni 5Al 3 and so on between Ni-W-P deposit and Al matrix after being heated at 400 °C for 1 h.

  20. A new in vivo replica technique for scanning electron microscope study of dental plaque morphology.

    PubMed

    Lambrechts, P; van Steenberghe, D; Vanherle, G

    1982-05-01

    For the micro-morphological investigation of soft oral tissues and deposits on the teeth in vivo, the use of an accurate replica technique is essential if the object under study cannot be examined directly. The conventional replica techniques based on resin or elastomer positive dies, have some limitations due to the instability of the sample die in the scanning electron microscope (S.E.M) conditions and artifacts induced at higher magnifications. Therefore, a new replica technique has been developed using a low viscosity impression material that is subsequently copperplated and poured with synthetic plaster. This offers a stable metal positive die suitable for direct examination in the S.E.M. without prior gold evaporation. Higher magnifications (greater than 7500) are easily obtained without the danger of artifacts. Reproduction of details is of a high order, and the reproduction ability depends only on the accuracy of the first impression. This technique offers new possibilities of discerning fine changes in surface detail in longitudinal clinical investigations.

  1. Scanning electron microscopic study on the lingual papillae of the Japanese insectivora.

    PubMed

    Kobayashi, S; Arai, S; Tomo, S; Shimoda, T; Shimamura, A; Yamada, H

    1989-03-01

    The tongue and lingual papillae of the Japanese Insectivora, the Shinto shrew (Sorex caecuiens saevus), the long-clawed shrew (S. unguiculatus), the dsinezumi shrew (Crocidura dsinezumi dsinezumi) and the Japanese water shrew (Chimarrogale himalyica platycephala), were observed by scanning electron microscope. The tongue of these animals had two vallate papillae. In two species of the Sorex a papilla in the vallate papilla was surrounded by two separated trenches, but in the other species it was surrounded by only a continuous trench and a clear vallum. The fungiform papillae in the Sorex were less developed than those of the other species. In the Sorex and Crocidura, there was no filiform papilla on the lingual apex. These genera, however, have papillary projections in the margin of the lingual apex. The results of this investigation suggest that the Sorex and Crocidura indicate an ancient form of the mammalian tongue. These characters, furthermore, were compared among seven species in six genera added three species observed by Kobayashi et al. (1983) to this study.

  2. Comprehensive Study of Hydrated IDPs: X-Ray Diffraction, IR Spectroscopy and Electron Microscopic Analysis

    NASA Technical Reports Server (NTRS)

    Nakamura, K.; Keller, L. P.; Nakamura, T.; Noguchi, T.; Nozaki, W.; Tomeoka, K.

    2003-01-01

    Chondritic hydrated interplanetary dust particles (IDPs) comprise up to 50% of all IDPs collected in the stratosphere(1). Although much is known about the mineralogy, chemistry and carbon abundance of hydrated IDPs (2-4) controversies still exist regarding their formation, history, and relationship to other primitive solar system materials. Hydrated IDPs are generally believed to be derived from asteroidal sources that have undergone some degree of aqueous alteration. However, the high C contents of hydrated IDPs (by 2 to 6X CI levels (3,4) indicate that they are probably not derived from the same parent bodies sampled by the known chondritic meteorites. We report the comprehensive study of individual hydrated IDPs. The strong depletion in Ca (I) has been used as a diagnostic feature of hydrated IDPs. The particles are embedded in elemental sulfur or low viscosity epoxy and ultramicrotomed thin sections are observed using a transmission electron microscope (TEM) equipped with an energy-dispersive X-ray detector (EDX) followed by other measurements including: 1) FTIR microspectroscopy to understand the significant constraints on the organic functionality and the nature of the C-bearing phases and 2) powder X-ray difiaction using a synchrotron X-ray source to understand the bulk mineralogy of the particles.

  3. A light and electron microscope study on the origin of Foà-Kurloff cells.

    PubMed

    Kittas, C; Parsons, M A; Henry, L

    1979-06-01

    Numerous Foà-Kurloff (FK) cells have been found in the circulation, spleen, bone marrow, thymus and placenta of guinea pigs under endogenous or exogenous oestrogenic stimulation. The origin of these cells is obscure. In the present experiment, the distribution of FK cells in organs other than those stated above was studied following gonadectomy and hexoestrol administration in guinea pigs of both sexes for either 1 or 10 weeks. More FK cells than those expected from the vascularity of the organ were found in the liver and lungs of male and female animals. The number of FK cells in these organs was larger after the long-term treatment with hexoestrol and it was accompanied by a significant decrease in the number of Kupffer cells of the liver. The latter observation is in contrast to previous reports of increased numbers of Kupffer cells in the liver of oestrogen-receiving mice, a species not producing FK cells. These observations suggest a relation between the two types of cells. No transformation of mature Kupffer cells into FK cells was seen with the electron microscope. However, other findings suggest that both Kupffer cells and FK cells may well be derived from a common precursor of MPS in the bone marrow.

  4. An universal and accurate replica technique for scanning electron microscope study in clinical dentistry.

    PubMed

    Lambrechts, P; Vanherle, G; Davidson, C

    1981-09-01

    One of the main concerns of dental research is the observation of the oral tissues and the materials applied to the dentition. The changes in composition and structure of the outer surfaces and the materials deposited on these surfaces are of special interest. In the literature, a variety of replica techniques for these purposes is described (Grundy in 1971 [12]; Saxton in 1973 [25]). The use of these techniques is limited because of artifacts in the samples, and a restricted resolution power resulting from useful magnifications in the order of 800x. An accurate and universal replica technique for the examination of specimens to be viewed under the SEM has been developed. The first impression is made by a light body silicone elastomer (President Coltene). The positive replica is made by electrodeposition of copper in an electro plating bath (Acru plat 5 electronic, Dr. Th. Wieland, D-7530 Pforzheim). The reliability and accuracy of this replica technique was verified by a scanning electron microscopic comparison of the replicas and the actual structures of etched enamel. To illustrate the applicability of the replica technique to structures with much lower hardness, also high resolution images of dental plaque were produced. The copper surface offers a perfect, original and proper electroconductive medium that withstands the bombardment of electrons and the relatively severe conditions in the scanning electron microscope. Reproducibility was accurate as judged by the duplication in position, size, and shape of the fine detail at magnifications of 7500x offering a resolution of 25 nm.

  5. [The evaluation of acrylic resins for the study of nondecalcified human teeth with the light and electronic microscopes].

    PubMed

    Botti, F; Martignoni, M; Scala, C; Cocchia, D

    1995-04-01

    Resin embedding of human teeth for light and transmission electron microscopic studies becomes difficult without previous decalcification. The limited and slow infiltration of the resin into hard tissues may cause problems during preparation and observation of the samples. Moreover the type of resin that is used may affect the morphologic preservation of both tissues and cellular elements. Recently there has been an increasing number of studies on the application of acrylic resins in light and electron microscopy, in order to overcome problems encountered with the use of epoxy resins still utilized in morphologic studies. We compared different acrylic resins (Technovit 7200 VLC, LR White, LR Gold, Bioacryl) in order to understand which one was more suitable for undecalcified human dental tissues under light and transmission electron microscope. Evaluation of such resins was performed using the following criteria: ease of cutting with ultramicrotome, soft and hard tissues infiltration, uptake of tissue stains for both light and electron microscopy, morphologic preservation and stability under electron beam. This study, carried out on the pulp area comprising predentin and dentin, showed excellent quality of Bioacryl and LR Gold, the two resins presenting, by far, the best results among all the different types tested. The optimal morphologic preservation obtained with such resins is indicated for light and electron microscopic studies, allowing their application in different fields of dental research.

  6. Electron microscope and low-angle x-ray diffraction studies of the nerve myelin sheath.

    PubMed

    FERNANDEZ-MORAN, H; FINEAN, J B

    1957-09-25

    1. A close correlation has been obtained between high resolution electron microscopy and low-angle x-ray diffraction studies of the myelin sheath of frog and rat peripheral and central nerves. Extensive studies were performed by application of both techniques to the same specimens, prepared for examination by OsO(4) or KMnO(4) fixation, and embedding either in methacrylate or in gelatin employing a new procedure. Controlled physical and chemical modifications of the myelin sheath prior to fixation were also investigated. 2. A correspondence was established between the layer spacings observed in electron micrographs and the fundamental radial repeating unit indicated by the low-angle x-ray diffraction patterns. The variations in relative intensities of the low-angle x-ray reflections could be related to the radial density distributions seen in the electron micrographs. 3. An analysis of the preparation procedures revealed that OsO(4) fixation introduces a greater shrinkage of the layer spacings and more pronounced changes in the density distribution within the layers than KMnO(4) fixation. The effects of methacrylate and gelatin embedding are described, and their relative merits considered in relation to the preservation of myelin structure by OsO(4) fixation. 4. The experimental modifications introduced by freezing and thawing of fresh whole nerve are described, particularly the enhancement of the intermediate lines and the dissociation of the layer components in the myelin sheath. A characteristic collapsing of the radial period of the sheath is observed after subjecting fresh nerve trunks to prolonged and intense ultracentrifugation. 5. Controlled extraction of fresh nerve with acetone at 0 degrees C., which preferentially removes cholesterol, produces characteristic, differentiated modifications of the myelin sheath structure. Electron microscopy reveals several types of modifications within a single preparation, including both expanded and collapsed layer

  7. Ballistic-Electron-Emission Microscope

    NASA Technical Reports Server (NTRS)

    Kaiser, William J.; Bell, L. Douglas

    1990-01-01

    Ballistic-electron-emission microscope (BEEM) employs scanning tunneling-microscopy (STM) methods for nondestructive, direct electrical investigation of buried interfaces, such as interface between semiconductor and thin metal film. In BEEM, there are at least three electrodes: emitting tip, biasing electrode, and collecting electrode, receiving current crossing interface under investigation. Signal-processing device amplifies electrode signals and converts them into form usable by computer. Produces spatial images of surface by scanning tip; in addition, provides high-resolution images of buried interface under investigation. Spectroscopic information extracted by measuring collecting-electrode current as function of one of interelectrode voltages.

  8. Scanning-electron-microscope study of normal-impingement erosion of ductile metals

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Salik, J.

    1980-01-01

    Scanning electron microscopy was used to characterize the erosion of annealed copper and aluminum surfaces produced by both single- and multiple-particle impacts. Macroscopic 3.2 mm diameter steel balls and microscopic, brittle erodant particles were projected by a gas gun system so as to impact at normal incidence at speeds up to 140 m/sec. During the impacts by the brittle erodant particles, at lower speeds the erosion behavior was similar to that observed for the larger steel balls. At higher velocities, particle fragmentation and the subsequent cutting by the radial wash of debris created a marked change in the erosion mechanism.

  9. Ultrastructural Analysis of Incinerated Teeth by Scanning Electron Microscope – A Short Study

    PubMed Central

    Swamy, Sugunakar Raju Godishala; Muddana, Keerthi

    2016-01-01

    Introduction In forensic context precise knowledge on physical and histological changes of teeth subjected to high temperatures is of great importance. Preserving fragile incinerated teeth for physical, histological and ultra structural examinations is essential in fire investigations involving the origin of fire, its cause as well as the identification of victims which relies on a thorough understanding of the structural changes in dental tissues subjected to heat. Aim The study was conducted to evaluate the physical and ultrastructural changes seen in freshly extracted teeth when subjected to gradual heating at different temperatures using Scanning Electron Microscope (SEM). Settings and Design Freshly extracted teeth collected from subjects of different age groups were subjected to different temperatures using laboratory furnace and findings were correlated to the temperature. Materials and Methods The study was conducted on 60 healthy freshly extracted teeth belonging to age group between 20-30 years. Group A comprised of control group which included teeth that were not subjected to heat whereas Group B, C and D comprised of teeth that were subjected to different temperatures i.e., 100oC, 300oC and 600oC respectively for a time of fifteen minutes in laboratory furnace, after which they were processed for SEM examination. Each group included 15 teeth; 5 anteriors, 5 premolars and 5 molars. Results Examination under SEM revealed definite ultra structural changes which were explicitly seen at particular temperatures (100oC, 300oC and 600oC). The samples showed cracks and charring of the tooth structure with ultra structural findings such as pebbles, granules, dots on enamel surface; and soap bubble pattern, honey comb pattern and snail track pattern on cementum surface. Conclusion Because of the consistency of morphological changes and the ultra structural patterns at various temperatures, evaluation of incinerated dental remains using SEM can provide additional

  10. Ultrastructural Analysis of Incinerated Teeth by Scanning Electron Microscope – A Short Study

    PubMed Central

    Swamy, Sugunakar Raju Godishala; Muddana, Keerthi

    2016-01-01

    Introduction In forensic context precise knowledge on physical and histological changes of teeth subjected to high temperatures is of great importance. Preserving fragile incinerated teeth for physical, histological and ultra structural examinations is essential in fire investigations involving the origin of fire, its cause as well as the identification of victims which relies on a thorough understanding of the structural changes in dental tissues subjected to heat. Aim The study was conducted to evaluate the physical and ultrastructural changes seen in freshly extracted teeth when subjected to gradual heating at different temperatures using Scanning Electron Microscope (SEM). Settings and Design Freshly extracted teeth collected from subjects of different age groups were subjected to different temperatures using laboratory furnace and findings were correlated to the temperature. Materials and Methods The study was conducted on 60 healthy freshly extracted teeth belonging to age group between 20-30 years. Group A comprised of control group which included teeth that were not subjected to heat whereas Group B, C and D comprised of teeth that were subjected to different temperatures i.e., 100oC, 300oC and 600oC respectively for a time of fifteen minutes in laboratory furnace, after which they were processed for SEM examination. Each group included 15 teeth; 5 anteriors, 5 premolars and 5 molars. Results Examination under SEM revealed definite ultra structural changes which were explicitly seen at particular temperatures (100oC, 300oC and 600oC). The samples showed cracks and charring of the tooth structure with ultra structural findings such as pebbles, granules, dots on enamel surface; and soap bubble pattern, honey comb pattern and snail track pattern on cementum surface. Conclusion Because of the consistency of morphological changes and the ultra structural patterns at various temperatures, evaluation of incinerated dental remains using SEM can provide additional

  11. Light and electron microscopic study on the pineal complex of the coelacanth, Latimeria chalumnae Smith.

    PubMed

    Hafeez, M A; Merhige, M E

    1977-03-01

    The pineal complex of the coelacanth, Latimeria chalumnae was studied light and electron microscopically. It consists of two vesicles representing parapineal and pineal organs. Both occur intracranially and openly communicate with each other and the brain ventricle. The entire complex shows a striking photoreceptor morphology with sensory, ependymal and nerve cells. The last cell type is more abundant in the parapineal vesicle than in the pineal organ. The following ultrastructural details of the parapineal are noteworthy: 1. The sensory cells possess large inner and outer segments protruding freely in the vesicular cavity. The outer segments measure 8-10 mum in length and consist of as many as 275 lamellae. The basal processes of these cells terminate in neuropil-like regions. Occasionally, dense granules (500-1000 A) of uncertain identity occur in the perinuclear and inner segment cytoplasm of the cells. 2. The supporting cells are of the ependymal type. Their cytoplasm contains a filamentous feltwork and pinocytotic vesicles, but lacks secretory granules. Cytosomes are particularly abundant in cell processes in the neuropil-like zones. The basal end-feet of these cells isolate the receptor and nerve cells from the perivascular space. 3. In the neuropil-like regions, terminals of sensory cells make synaptic contacts with neuronal dendrites. Synaptic ribbon-like profiles in the terminals characterize the contact zones. Only unmyelinated nerve fibers could be observed in the small area of the tissue examined. The results are discussed with regard to photoreceptive and secretory functions of the pineal complex and its evolution in lower vertebrates.

  12. The atrioventricular valves of the mouse. I. A scanning electron microscope study.

    PubMed Central

    Icardo, J M; Arrechedera, H; Colvee, E

    1993-01-01

    This paper reports a scanning electron microscope study of the morphology of the atrioventricular (AV) valves in the mouse. The leaflet tissue of the 2 AV valves consists of a continuous veil that shows no commissures or clefts. In all instances, the chordae that arise from the papillary system merge with the free border of the leaflet tissue. No distinct terminations of chordae were observed on the ventricular face of the valves. The leaflet tissue of the right AV valve can be divided into parietal and septal components on the basis of the insertion into the ventricular wall and of the papillary system. While the septal component is similar in shape, location and tension apparatus to the septal tricuspid leaflet in man, the parietal component appears to correspond to the anterior and posterior human leaflets. This segment of the valve is served by 3 papillary muscles that arise from the septal wall. The right AV valve is not a tricuspid structure from the morphological standpoint, but appears to function as such because of the particular attachment of the papillary muscles. The leaflet tissue of the mitral valve is served by 2 papillary muscles, anterior and posterior, which consist of muscular trabeculae extending from the heart apex to the base of the valve. These muscles remain associated with the ventricular wall. The leaflet tissue attaches directly to these papillary muscles, which give rise to a very small number of slender chordae. There are thus several important differences between the AV valves of the mouse and man.(ABSTRACT TRUNCATED AT 250 WORDS) Images Fig. 1 Fig. 2 Fig. 3 Figs 4-6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 PMID:8509303

  13. Scanning and transmission electron microscopic study of the lung of the newt, Triturus alpestris Laur.

    PubMed

    Goniakowska-Witalińska, L

    1980-01-01

    The lungs of Triturus alpestris Laur. were investigated with the scanning and transmission electron microscopes. Dimensions of the cell bodies of pneumocytes and ciliated cells, as well as the thickness of the air-blood barrier, were determined. The lungs of the newt form two simple sacs without septa. A ciliated epithelium containing goblet cells lines the pulmonary vein and partially the pulmonary artery. The remainder of the lung surface is covered internally by respiratory epithelium consisting of one type of cell and only occasionally showing the presence of single ciliated cells. All cells, ciliated, goblet and pneumocytes, contain in their cytoplasm lamellar bodies. Multivesicular bodies and numerous vesicles of variable electron density also occur in the cytoplasm of pneumocytes. Atypical mitochondria can be found in all cell types of the lung. Fixation with addition of tannic acid reveals the surface lining film. Tubular myelin figures were not observed.

  14. Atomic-Scale Study Of Complex Cobalt Oxide Using Scanning Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Gulec, Ahmet

    Cobalt oxides offer a rich ?eld for the formation of novel phases, including superconductors and exotic magnetic phases, involving a mixed valence state for cobalt and/or the presence of oxygen vacancies. Having spin states, such as, low spin (LS), high spin (HS), and intermediate spin (IS), cobalt oxides differ from other 3d metal oxides The presence of such spin states make the physics of the cobalt oxides so complicated that it has not yet been completely understood. In order to improve our understanding of the various phase transitions observed in Cobalt oxides and to comprehend the relationship between crystal and electronic structure, both high energy resolution and high spatial resolution are essential. Fortunately, transmission electron microscopy (TEM) is a technique which is capable of ful?lling both of these requirements. In this thesis, I have utilized unique techniques in a scanning transmission electron microscope (STEM) to analyze the atomic-scale structure-property relationship, both at room temperature and through insitu cooling to liquid nitrogen (LN2) temperature. In particular, by using correlated Z-contrast imaging, electron energy loss spectrum (EELS) and electron energy loss magnetic circular dichroism (EMCD), the structure, composition, bonding and magnetic behavior are characterized directly on the atomic scale.

  15. An electron microscopic study of the intestinal villus. II. The pathway of fat absorption.

    PubMed

    PALAY, S L; KARLIN, L J

    1959-05-25

    The intestinal pathway for absorbed fat was traced in thin sections of intestinal villi from rats fed corn oil by stomach tube after a fast of 24 to 40 hours. For electron microscopy the tissues were fixed in chilled buffered osmium tetroxide and embedded in methacrylate. For light microscopy, other specimens from the same animals were fixed in formal-calcium, mordanted in K(2)Cr(2)O(7), and embedded in gelatin. Frozen sections were stained with Sudan black B or Sudan IV. About 20 minutes after feeding, small fat droplets (65 mmicro maximal diameter) appear in the striated border between microvilli. At the same time fat particles are seen within pinocytotic vesicles in the immediately subjacent terminal web. In later specimens the fat droplets are generally larger (50 to 240 mmicro) and lie deeper in the apical cytoplasm. All intracellular fat droplets are loosely enveloped in a thin membrane, the outer surface of which is sometimes studded with the fine particulate component of the cytoplasm. This envelope, apparently derived from the cell surface by pinocytosis, has at this stage evidently become a part of the endoplasmic reticulum. Just above the nucleus numerous fat droplets lie clustered within the dilated cisternae of the Golgi complex. As absorption progresses fat droplets appear in the intercellular spaces of the epithelium, in the interstitial connective tissue spaces of the lamina propria, and in the lumen of the lacteals. All of these extracellular fat droplets are devoid of a membranous envelope. The picture of fat absorption as reconstructed from these studies involves a stream of fat droplets filtering through the striated border, entering the epithelial cell by pinocytosis at the bases of the intermicrovillous spaces, and coursing through the endoplasmic reticulum to be discharged at the sides of the epithelial cell into extracellular spaces. From the epithelial spaces, the droplets move into the lamina propria and thence into the lymph. If the lumen

  16. Palisade pattern of mormyrid Purkinje cells: a correlated light and electron microscopic study.

    PubMed

    Meek, J; Nieuwenhuys, R

    1991-04-01

    The present study is devoted to a detailed analysis of the structural and synaptic organization of mormyrid Purkinje cells in order to evaluate the possible functional significance of their dendritic palisade pattern. For this purpose, the properties of Golgi-impregnated as well as unimpregnated Purkinje cells in lobe C1 and C3 of the cerebellum of Gnathonemus petersii were light and electron microscopically analyzed, quantified, reconstructed, and mutually compared. Special attention was paid to the degree of regularity of their dendritic trees, their relations with Bergmann glia, and the distribution and numerical properties of their synaptic connections with parallel fibers, stellate cells, "climbing" fibers, and Purkinje axonal boutons. The highest degree of palisade specialization was encountered in lobe C1, where Purkinje cells have on average 50 palisade dendrites with a very regular distribution in a sagittal plane. Their spine density decreases from superficial to deep (from 14 to 6 per micron dendritic length), a gradient correlated with a decreasing parallel fiber density but an increasing parallel fiber diameter. Each Purkinje cell makes on average 75,000 synaptic contacts with parallel fibers, some of which are rather coarse (0.45 microns), and provided with numerous short collaterals. Climbing fibers do not climb, since their synaptic contacts are restricted to the ganglionic layer (i.e., the layer of Purkinje and eurydendroid projection cells), where they make about 130 synaptic contacts per cell with 2 or 3 clusters of thorns on the proximal dendrites. These clusters contain also a type of "shunting" elements that make desmosome-like junctions with both the climbing fiber boutons and the necks of the thorns. The axons of Purkinje cells in lobe C1 make small terminal arborizations, with about 20 boutons, that may be substantially (up to 500 microns) displaced rostrally or caudally with respect to the soma. Purkinje axonal boutons were observed to

  17. Investigations in space-related molecular biology. [cryo-electron microscopic and diffraction studies on terrestrial and extraterrestrial specimens

    NASA Technical Reports Server (NTRS)

    Fernandez-Moran, H.; Pritzker, A. N.

    1974-01-01

    Improved instrumentation and preparation techniques for high resolution, high voltage cryo-electron microscopic and diffraction studies on terrestrial and extraterrestrial specimens are reported. Computer correlated ultrastructural and biochemical work on hydrated and dried cell membranes and related biological systems provided information on membrane organization, ice crystal formation and ordered water, RNA virus linked to cancer, lunar rock samples, and organometallic superconducting compounds. Apollo 11, 12, 14, and 15 specimens were analyzed

  18. [Regulatory elements in the skin epithelium of Saccoglossus mereschkowskii (Enteropneusta, Hemichordata): electron microscopic and immunocytochemical study].

    PubMed

    Stoliarova, M V; Val'kovich, E I

    2013-01-01

    The aim of this investigation was to demonstrate the regulatory elements in the skin epithelium of Enteropneusta which are supposed to be related to the chordate ancestors. Using electron microscopy, it was found that in the skin epithelium of a representative of enteropneusts Saccoglossus mereschkowskii, the basal parts of some epitheliocytes took part in formation of a nerve layer. These cells were considered as receptor ciliated cells. The granular epithelial cells were shown to release secretion according to both exocrine and endocrine mechanism; these cells were characterized as endocrine-like regulatory cells. Fine granular cells possibly represent special receptor-endocrine-like cell type. The immunocytochemical detection of FMRFamid neuropeptide localization in histological sections confirmed the electron microscopic data on the presence of receptor and endocrine-like cells in the epithelium. It is suggested that the skin epithelium of Enteropneusta contains a peculiar neuro-endocrine regulatory system that is represented by receptor cells, receptor-endocrine-like cells of an open type and nerve elements of the nerve layer. PMID:24707736

  19. Development and hatching mechanism of Fasciola eggs, light and scanning electron microscopic studies.

    PubMed

    Hussein, Abdel-Nasser A; Hassan, Ismael M; Khalifa, Refaat M A

    2010-07-01

    Both light microscopy and scanning electron microscopy were used in the description. There were variable measurements of eggs from the same fluke and there was no relationship between the size of the fluke and size of eggs. Light microscopy revealed that the operculum has different shapes in Fasciola gigantica and F. hepatica. Under normal laboratory conditions of temperature (26 ± 1 °C), miracidia of F. gigantica developed within 12-16 days period, but those of F. hepatica developed within a period of 13-15 days. The miracidia of F. gigantica measured 110 × 70 μm and that of F. hepatica measured 136 × 74 μm. The life span of the miracidium in F. gigantica ranged between 9 and 12 h, while in F. hepatica the life span did not exceed 10 h. Miracidial epidermal plates in miracidium of F. gigantica were found to be 20 plates arranged in four tiers of six, four, six and four. Hatching process was recorded using scanning electron microscope, and it indicated partially opened operculum. PMID:23961086

  20. [Regulatory elements in the skin epithelium of Saccoglossus mereschkowskii (Enteropneusta, Hemichordata): electron microscopic and immunocytochemical study].

    PubMed

    Stoliarova, M V; Val'kovich, E I

    2013-01-01

    The aim of this investigation was to demonstrate the regulatory elements in the skin epithelium of Enteropneusta which are supposed to be related to the chordate ancestors. Using electron microscopy, it was found that in the skin epithelium of a representative of enteropneusts Saccoglossus mereschkowskii, the basal parts of some epitheliocytes took part in formation of a nerve layer. These cells were considered as receptor ciliated cells. The granular epithelial cells were shown to release secretion according to both exocrine and endocrine mechanism; these cells were characterized as endocrine-like regulatory cells. Fine granular cells possibly represent special receptor-endocrine-like cell type. The immunocytochemical detection of FMRFamid neuropeptide localization in histological sections confirmed the electron microscopic data on the presence of receptor and endocrine-like cells in the epithelium. It is suggested that the skin epithelium of Enteropneusta contains a peculiar neuro-endocrine regulatory system that is represented by receptor cells, receptor-endocrine-like cells of an open type and nerve elements of the nerve layer.

  1. A STUDY OF THE ULTRASTRUCTURAL LOCALIZATION OF HAIR KERATIN SYNTHESIS UTILIZING ELECTRON MICROSCOPIC AUTORADIOGRAPHY IN A MAGNETIC FIELD

    PubMed Central

    Nakai, Takashi

    1964-01-01

    The sites of the incorporation of labeled cystine into keratinizing structures were studied in electron microscopic autoradiographs. The tracer used was cystine labeled with S35 emitting long-range ionizing particles. During exposure for 1 to 2 months, according to our method of electron microscopic autoradiography, emulsion-coated specimens were exposed to a static magnetic field which appeared to result in a marked increase in the number of reacted silver grains. In young Swiss mice receiving intraperitoneal injections at 1, 3, and 6 hours before biopsy, conventional autoradiography demonstrated that S35-cystine was intensely localized in the keratogenous zone of anagen hair follicles, and that the radioactivity there increased in intensity progressively with time while the radioactivity in the hair bulb always remained very low. Our observations with electron microscopic autoradiography in a magnetic field appeared to indicate that at 3 and 6 hours after injection the S35-cystine was directly and specifically incorporated into tonofibrils in the hair cortex and into amorphous keratin granules of the hair cuticle layer, possibly without any particular concentration of this substance in the other cellular components. There seemed to be an appreciable concentration of cystine in tonofibrils of the cuticle of the inner root sheath. However, trichohyalin granules in the hair medulla and inner root sheath failed to show any evidence of cystine concentration. The improved sensitivity of the electron microscopic autoradiography with S35-cystine appeared to be partly due to the application of a static magnetic field. However, the reason for this could not be explained theoretically. PMID:14154496

  2. Study of the thermal degradation mechanism of a composite propellant. [using electron microscopes

    NASA Technical Reports Server (NTRS)

    Schmidt, W. G.

    1975-01-01

    The current experimental program was designed to systematically investigate the role of the oxidizer in the thermal degradation process of composite propellants. The scanning electron microscope (SEM) was used to examine the failure sites in thermally degraded propellant samples. The formulation variables tested were oxidizer purity, oxidizer particle size, and oxidizer to binder bonding agent. The binder, a saturated hydrocarbon, was kept constant throughout the experiments. The oxidizers were: AP, chlorate-doped AP, arsenate-doped AP, and phosphate-doped AP. The oxidizer particle size distribution was 60% of the large fraction and 40% of the small fraction. The bonding agent, when present, was used at the 0.15% level. The data showed that both the oxidizer purity and particle size had an important affect on the thermal degradation process. The affect of the oxidizer particle size was more noticeable at the higher temperature and stress levels. An examination of the failure site, by SEM, of propellants subject to these latter conditions indicated that the fracturing of the large oxidizer particles led to the propellant cracking.

  3. Cryoscanning electron microscopic study of the surface amorphous layer of articular cartilage.

    PubMed Central

    Kobayashi, S; Yonekubo, S; Kurogouchi, Y

    1995-01-01

    In order to elucidate the structure near the articular surface, frozen unfixed hydrated articular cartilage with subchondral bone from the pig knee was examined using a cryoscanning electron microscope (cryo-SEM). This method is considered to reduce the introduction of artefacts due to fixation and drying. An amorphous layer, without a collagen-fibril network or chondrocytes, covered most of the surface of the cartilage. This layer was termed the surface amorphous layer. It showed various appearances, which were classified into 4 groups. The average thickness of the layer did not differ among the 8 anatomical regions from which the specimens were taken. The thickness of the layer was found to correlate with the type of appearance of the layer. The 4 appearances associated with thicknesses in descending order are: 'streaked', 'foliate', 'spotted', and 'vestigial'. The surface layer observed in the cryo-SEM was thicker than that observed by a conventional SEM. This difference may be attributable to dehydration of the specimen used in specimen preparation for the latter technique. The layer was also observed in articular cartilage taken from human and rabbit knees. The layer was found to be unstable and to have very variable features. Its thickness and appearance may be influenced by various factors such as dehydration, fluid absorption or mechanical stress. Images Fig. 1 Fig. 3 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16 Fig. 17 Fig. 18 Fig. 19 PMID:7592006

  4. Equine laryngeal hemiplegia. Part II. An electron microscopic study of peripheral nerves.

    PubMed

    Cahill, J I; Goulden, B E

    1986-10-01

    The recurrent laryngeal nerves were examined by electron microscopy in five control, four subclinical and four clinical laryngeal hemiplegic horses. In addition, the peroneal nerve was examined in two horses in the latter group. The distally distributed loss of large myelinated fibres in the left recurrent laryngeal nerve seen by light microscopy was confirmed. In addition, active axonal pathology was found to be more evident than indicated by light microscopic investigations. The onion bulb formations observed indicated the repetitive nature of the damaging influence to nerve fibres. Although the pathological changes were most obvious in the distal left recurrent laryngeal nerve, alterations similar in type and distribution were present in other areas of the left and right nerves, and in the distal hindlimb nerves. The observation of fibres with inappropriately thick myelin sheaths relative to their axonal calibre, was confirmed statistically by determining the regressions of axis cylinder perimeter against the number of myelin lamellae. In conclusion, the peripheral nerve pathology of equine laryngeal hemiplegia was demonstrated to be a distally distributed loss of myelinated fibres, with considerable active axonal damage, in conjunction with axonal atrophy. These features suggest that this disease may be classified as a distal axonopathy.

  5. Electron microscopic studies of damage evolution in fission neutron-irradiated metals

    NASA Astrophysics Data System (ADS)

    Shimomura, Y.; Yoshida, H.; Kiritani, M.; Kitagawa, K.; Yamakawa, K.

    1985-08-01

    The same kinds of specimens of both foil and bulk of metals, as those irradiated previously with D-T neutrons at RTNS-II, were irradiated with fission neutrons at KUR. The irradiations were performed at 20 and 350 K to fluences of 5 × 10 16 and 1 × 10 19 n/cm 2(E > 0.1 MeV), respectively. The results on pure gold are described to exemplify the typical value of cascade defects. A cascade in fission neutron irradiated gold consists of 2.2 small defects on average. This is compared with 6.7 small defects for the fusion neutron irradiation. The cross section for the formation of observed cascade defects is 0.15 barn, which is a twelveth of that in fusion neutron irradiation. The cryotransfer of the thin foil to the electron microscope was carried out to observe the cascade defects at low temperatures. The average size of cascade defects in fission neutron-irradiated gold was much smaller than that in fusion irradiation. The damage evolution in the bulk specimen was also examined.

  6. [The influence of local anesthetics on corneal epithelium. A scanning electron microscopic study (author's transl)].

    PubMed

    Brewitt, H; Honegger, H

    1978-09-01

    The effect of different local anesthetics (Cocain 4%, Lidocaine 2%, Proparacain) on the corneal epithelium in rabbits was examined under scanning electron microscope. The experiment was divided into three groups. Group 1 received one application of two drops of the given local anesthetic for a reaction time of 5 minutes. Group 2 received two drops of the given anesthetic after 0, 5 and 10 minutes. The cornea was excised after 15 minutes. Group 3 were measured after a single application of Proparacain using a Schiötz or hand applanation tonometer according to Draeger. After a single dose of a local anesthetic principally the same changes in the surface of the cornea were observed with all the preparations used: a distinct decrease in the number of microvilli and microplicae, disruption of the intercellular spaces and the prominence of the cell nuclei which under normal conditions are not visible. After several applications the greater toxicity of Cocain compared with the other preparations was clearly seen through the disruption of the plasma membrane and the cytoplasm. The damage effected several layers of cells. Tonometry when correctly performed causes no additional damage to the cell surface.- The effect of local anesthetics on the cell membrane can only take place after the disruption of the tear film. The results emphasize that local anesthetics should only be applied when absolutely essential.

  7. Electron microscope studies. Progress report, June 1, 1992--November 1, 1993

    SciTech Connect

    Crewe, A.V.; Kapp, O.H.

    1993-11-01

    During the past year we have continued our work on the mirror-corrected high resolution STEM. We have made significant progress in the design and fabrication of the various microscope sub-systems and have completed a new display system. Additional calculations and computer simulations have been performed to confirm the original theory of mirror correctors. In our biological work we have made a careful study of the structure of globins, vertebrate and invertebrate, using the accumulated information contained in the Brookhaven Data Bank (3D structures), the Protein Identification Resource (ID sequences) and the data we have obtained with the STEM. Statistical templates have been generated to predict various classes of globins.

  8. Light and transmission electron microscopic studies on trophozoites and cyst-like stages of Histomonas meleagridis from cultures.

    PubMed

    Munsch, Mareike; Lotfi, Abdulrahman; Hafez, Hafez Mohammed; Al-Quraishy, Saleh; Mehlhorn, H

    2009-02-01

    The present study deals with Berlin strains of Histomonas meleagridis, the specimens of which were cultivated in Dwyer's medium. The light and electron microscopic examination revealed that the cultivated trophozoite stages (reaching about 10 mum in size) appeared more or less spherical, although their surface (covered by a single membrane) showed amoeba-like waves. All stages were uni-nucleated and reproduced by binary fission with an extranuclear spindle apparatus. Some trophozoites appeared ovoid and possessed a single flagellum with a typical microtubular 9 x 2 + 2 arrangement. Furthermore, the latter were characterized by an inner row of typical microtubules (remnant of an axostyle) and a Golgi apparatus (both adjacent to the nucleus), multivesicular structures, hydrogenosomes, and many food vacuoles containing either starch grains or bacteria. Their cytoplasm was densely filled with glycogen granules and ribosomes. Similar stages were also documented in the caeca and cloaca of chicken when being inoculated (via cloaca) with such culture stages. In addition to these typical trophozoites, the cultures contained a low number of 10-mum-sized spherical cyst-like stages with a surrounding amorphous layer. The cytoplasm of some of these cyst-like stages-when studied by electron microscopy-appeared with two membranes or had formed an amorphic, cyst-wall-like layer at their surface, apparently corresponding to their light microscopical appearance. Such stages might be involved in transmission from one host to another and probably have been missed before in microscopical examinations of infected poultry. PMID:18998167

  9. [Electron microscopic study of the intestinal epithelium of Saccoglossus mereschkowskii (Enteropneusta, Hemichordata)].

    PubMed

    Stoliarova, M V

    2011-01-01

    Epithelium of the hepatic region of the intestine in Saccoglossus mereschkowskii, a representative of enteropneusts (Enteropneusta, Hemichordata) standing at the base of Chordata, has been investigated using electron microscope. The ultrastructure of ciliated and granular epithelial cells, elements of the intraepithelial nerve layer, and intercellular junctions have been characterized. The data concerning details of the organization of the ciliary apparatus and rootlets system are presented. It is justified the presence of complicated supporting construction of cilia which performs a mechanical stabilizing function and possibly also provide synchronization of ciliary movements. The presence of cilia with two centrioles is considered as an adaptation to high functional load on ciliary apparatus. Well developed bundles of myofilaments are found in the cytoplasm of the basal portions of ciliary cells that characterizes these cells as myoepithelial. The features indicating the role of ciliary cells in absorption are described. The capability of these cells to balloon-like secretion is considered. Data on the accumulation of food reserves in the form of lipid droplets and glycogen in the cell cytoplasm are presented. Ciliated cells are characterized by their function as ciliated secretory-absorptive myoepithelial cells. Based on the location of secretory granules both in the apical and basal portions of granular cells, an exocrine-endocrine function of these cells has been suggested. Typical endocrine cells in the intestinal epithelium of S. mereschkowskii are absent. Several types of granules in the nerve fibers cytoplasm are described. Junctions between the nerve fibers and basal portions of ciliary and granular epithelial cells are found. Nerve regulation of contractile and secretory functions of epithelial cells is supposed. The presence of the regulatory nerve-endocrine system that includes receptor cells of open type, secretory endocrine-like cells and nerve

  10. [Electron microscopic study of the intestinal epithelium of Saccoglossus mereschkowskii (Enteropneusta, Hemichordata)].

    PubMed

    Stoliarova, M V

    2011-01-01

    Epithelium of the hepatic region of the intestine in Saccoglossus mereschkowskii, a representative of enteropneusts (Enteropneusta, Hemichordata) standing at the base of Chordata, has been investigated using electron microscope. The ultrastructure of ciliated and granular epithelial cells, elements of the intraepithelial nerve layer, and intercellular junctions have been characterized. The data concerning details of the organization of the ciliary apparatus and rootlets system are presented. It is justified the presence of complicated supporting construction of cilia which performs a mechanical stabilizing function and possibly also provide synchronization of ciliary movements. The presence of cilia with two centrioles is considered as an adaptation to high functional load on ciliary apparatus. Well developed bundles of myofilaments are found in the cytoplasm of the basal portions of ciliary cells that characterizes these cells as myoepithelial. The features indicating the role of ciliary cells in absorption are described. The capability of these cells to balloon-like secretion is considered. Data on the accumulation of food reserves in the form of lipid droplets and glycogen in the cell cytoplasm are presented. Ciliated cells are characterized by their function as ciliated secretory-absorptive myoepithelial cells. Based on the location of secretory granules both in the apical and basal portions of granular cells, an exocrine-endocrine function of these cells has been suggested. Typical endocrine cells in the intestinal epithelium of S. mereschkowskii are absent. Several types of granules in the nerve fibers cytoplasm are described. Junctions between the nerve fibers and basal portions of ciliary and granular epithelial cells are found. Nerve regulation of contractile and secretory functions of epithelial cells is supposed. The presence of the regulatory nerve-endocrine system that includes receptor cells of open type, secretory endocrine-like cells and nerve

  11. High-resolution electron microscopical study of cyst walls of Entamoeba spp.

    PubMed

    Chávez-Munguía, Bibiana; Martínez-Palomo, Adolfo

    2011-01-01

    Knowledge of the fine structural organization, molecular composition and permeability properties of the cell surface of intestinal protozoan cysts is important to understand the biologic basis of their resistance. Recent studies on the biology of the cyst walls of Entamoeba histolytica and Entamoeba invadens have considerably advanced knowledge on the cellular processes involved in the transport and surface deposition of the main cyst wall components. Using transmission electron microscopy, cytochemistry, scanning electron microscopy and freeze-fracture techniques, we have obtained new information. In mature cysts the permeability of Entamoeba cysts is limited to small molecules not by the cyst wall, but by the plasma membrane, as demonstrated with the use of ruthenium red as an electron-dense tracer. Cell walls of E. histolytica cysts are made up of five to seven layers of unordered fibrils 7-8 nm thick. Alcian blue stains a regular mesh of fibrils approximately 4 nm thick, running perpendicularly to the cyst wall. In addition, abundant ionogenic groups are seen in cyst walls treated with cationized ferritin. In the mature cysts of E. histolytica and E. invadens small cytoplasmic vesicles with granular material were in close contact with the plasma membrane, suggesting a process of fusion and deposition of granular material to the cell wall. The plasma membrane of mature cysts is devoid of intramembrane particles when analyzed with the freeze-fracture technique. When viewed with scanning electron microscopy the surface of E. histolytica cysts clearly differs from that of Entamoeba coli and E. invadens.

  12. Nephrotoxicity of ferric nitrilotriacetate. An electron-microscopic and metabolic study.

    PubMed Central

    Hamazaki, S.; Okada, S.; Ebina, Y.; Fujioka, M.; Midorikawa, O.

    1986-01-01

    Repeated intraperitoneal injections of ferric nitrilotriacetate (Fe-NTA) induce nephrotoxic features such as proximal tubular necrosis and renal failure, an unexpected phenomenon for a ferric compound. The mechanism of Fe-NTA toxicity was investigated by electron microscopy and respiration studies of renal cortical mitochondria in rats. Four hours after a single intraperitoneal injection of Fe-NTA, 5 mg iron/kg body wt, loss of microvilli, increased number of cytoplasmic vacuoles, electron-dense cytoplasmic deposits, mitochondrial swelling, karyorrhexis, and rupture of cytoplasmic membrane were observed in proximal tubular epithelia. At 24 hours, an increased number of cells had become necrotic. Polarographic studies of mitochondria from renal cortex 4 hours after Fe-NTA treatment showed a significant decrease in State 3 respiration and DNP-uncoupled respiration, whereas little change was observed in State 4 respiration and ADP/O. Images Figure 1 Figure 2 Figure 3 PMID:3706495

  13. LYTIC ACTIVITIES IN RENAL PROTEIN ABSORPTION DROPLETS. AN ELECTRON MICROSCOPICAL CYTOCHEMICAL STUDY.

    PubMed

    MILLER, F; PALADE, G E

    1964-12-01

    The digestive cycle following reabsorption of hemoglobin by cells of the proximal convoluted tubules in mouse kidney and the uptake of ferritin by glomerular mesangial cells in the kidney of normal and nephrotic rats were investigated by electron microscopical histochemical procedures. Mouse kidneys, sampled at closely spaced time points between 1 to 48 hours after intraperitoneal injection of hemoglobin, and rat (normal and nephrotic) kidneys, sampled at 30 minutes, 2 hours, and 48 hours after intravenous injection of ferritin, were fixed in glutaraldehyde, cut at 50 micro on a freezing microtome, incubated for acid phosphatase and thiolacetate-esterase, and postfixed in OsO(4). Satisfactory preservation of fine structure permitted the localization of the enzymatic reaction products on cell structures involved in uptake and digestion of exogenous proteins. The latter were identified either by their density (hemoglobin) or their molecular structure (ferritin). It was found that lysosomal enzymic activities and incorporated exogenous proteins occur together in the same membrane-bounded structures. In the cells of the proximal convolution, lytic activities become demonstrable within 1 hour after hemoglobin injection, appear first in apical vacuoles filled with hemoglobin, and persist in fully formed protein absorption droplets. At the end of the lytic cycle ( approximately 48 hours post injection), the cells have an increased population of polymorphic bodies which exhibit lytic activities. In smaller numbers, identical bodies occur in controls. It is concluded that they represent remnants of previous digestive events. The means by which the resorptive vacuoles acquire hydrolytic activities remain unknown. Fusion of newly formed vacuoles with residual bodies was not seen, and hemoglobin incorporation into such bodies was only occasionally encountered. Acid phosphatase activity was found sometimes in the Golgi complex, but enzyme transport from the complex to the

  14. Electron microscope study on the hepatic sinusoidal wall and fat-storing cells in the bat.

    PubMed

    Tanuma, Y; Ito, T

    1978-02-01

    The three cell types known to form the hepatic sinusoidal wall were electron microscopically observed in three kinds of bats captured in winter and summer. 1. The cytoplasmic extensions of sinusoidal endothelial cells consisted of continuous thicker parts ("cytoplasmic processes") and discontinuous thinner parts ("sieve plates"). The alternate disposition of the two parts was rather irregular, and the sizes, shapes and spacings of the fenestrae were variable. In the thinner parts with numerous small fenestrae, larger gaps were also mingled. The endothelium was simple-layered and devoid of basal lamina. Interendothelial junctions were found mainly between closely apposed margins of the "cytoplasmic processes" and agreed in structure with the "junctional complex" of WISSE (1970). 2. Kupffer cells, morphologically distinct from the endothelial cells, bulged strongly into the sinusoidal lumen. Provided with many microvillous pseudopods, they were stellate in appearance. They were fixed to the endothelial lining by small junctional areas which occurred between the Kupffer cell body and the "cytoplasmic processes" of the endothelium. 3. Fat-storing cells were located in the Disse's space. They generally contained only smaller amounts of lipid in a few droplets. So-called empty fat-storing cells were numerous, especially in winter bats. The perikaryonal cytoplasm revealed a large Golgi complex and well-developed granular endoplasmic reticulum. The three mesenchymal cell types of the sinusoidal wall possessed the centriole in common within the Golgi complex, but only the fat-storing cell was provided with the single cilium. Fat-storing cells extended cytoplasmic processes ramifying beneath the endothelial lining occasionally surrounding the sinusoids almost completely, and which seemed to reinforce the endothelial lining and to bring about the constriction of the sinusoid. In hypervitaminotic bats that daily received 6,000 I.U. vitamin A for three days, remarkable increase

  15. In-situ optical transmission electron microscope study of exciton phonon replicas in ZnO nanowires by cathodoluminescence

    SciTech Connect

    Yang, Shize; Tian, Xuezeng; Wang, Lifen; Wei, Jiake; Qi, Kuo; Li, Xiaomin; Xu, Zhi E-mail: xdbai@iphy.ac.cn Wang, Wenlong; Zhao, Jimin; Bai, Xuedong E-mail: xdbai@iphy.ac.cn; Wang, Enge E-mail: xdbai@iphy.ac.cn

    2014-08-18

    The cathodoluminescence spectrum of single zinc oxide (ZnO) nanowires is measured by in-situ optical Transmission Electron Microscope. The coupling between exciton and longitudinal optical phonon is studied. The band edge emission varies for different excitation spots. This effect is attributed to the exciton propagation along the c axis of the nanowire. Contrary to free exciton emission, the phonon replicas are well confined in ZnO nanowire. They travel along the c axis and emit at the end surface. Bending strain increases the relative intensity of second order phonon replicas when excitons travel along the c-axis.

  16. Vascularization of the pars distalis of the hypophysis in the toad, Bufo bufo (L.) (Amphibia, Anura). A comparative light microscopical and scanning electron microscopical study. I.

    PubMed

    1977-03-30

    The vascularization of the pars distalis of the hypophysis of the toad, Bufo bufo (L.), was studied by the traditional method of injecting a mixture of India-ink and gelatine into the circulatory system of the head via the arteria coratis communis. Further, methyl-methacrylate corrosion casts of the brains were made; the hypothalamo-adenohypophysial region of these corrosion casts was studied with the scanning electron microscope. The results showed that the portal vessels which arise from the median eminence do not supply distinct areas in the pars distalis as is supposed by the point-to-point-hypothesis. The portal vessels enter the ventro-median region of the pars distalis and branch off into a three-dimensional network of the secondary capillary plexus of the pars distalis. The plexus is made up mostly by four- to six-sided meshes. This angioarchitecture guarantees an optimal supply of the glandular cells of the pars distalis with nutritional factors and releasing hormones, on the one hand, and facilitates the removal of the hormones which are released by these cells, on the other hand. The venous drainage of the pars distalis is exerted mainly by two large veins, which bilaterally leave the dorso-lateral region (venous pole) of the pars distalis and by a few small veins, which drain into the wide, sinus-like vessel, which curves around the dorso-caudal region of the pars distalis and joins bilaterally the vena hypophysea transversa.

  17. The Sertoli cell of the water buffalo--an electron microscopic study.

    PubMed

    Azmi, T I; Bongso, T A; Harisah, M; Basrur, P K

    1990-01-01

    The ultrastructure of Sertoli cells in the seminiferous tubules of water buffaloes before and during sexual maturity was studied by transmission electron microscopy, with emphasis on the intranucleolar vesicular elements. Sertoli cells of animals under 12 months of age were distinguished from the germ cells by the presence of electron dense membrane bound bodies within their cytoplasm. These cells, referred to as basal indifferent supporting cells, were probably involved in the phagocytosis and elimination of degenerating spermatocytes, which failed to differentiate into spermatids and spermatozoa in animals under one year of age. In 12 month old animals, a few Sertoli cells exhibiting the vesicular elements appeared in the nucleolar region while in animals over 15 months of age Sertoli cells could be positively identified by the characteristic cytoplasm containing microtubules, elongated and electron dense mitochondria, extensive granular endoplasmic reticulum and the presence of spermatids in various stages of spermiogenesis. The vesicular elements in the nucleolar region of the Sertoli cells were most prominent at this stage. Ultrastructural features of the Sertoli cells revealed an abundance of ribosome-like particles surrounding the vesicles of varying size. Some of these vesicular elements contained amorphous material suggesting that they represent the products sequestered in the nuclear region for transport to the cytoplasm and that the process of spermiogenesis may be dependent on the ability of Sertoli cells to generate these products at sexual maturity.

  18. Transmission Electron Microscope Study of Platinum Group Element-Rich Micronuggets from Two Spherule Layer Intersections, Barberton Greenstone Belt, South Africa

    NASA Astrophysics Data System (ADS)

    Mohr-Westheide, T.; Greshake, A.; Wirth, R.; Reimold, W. U.; Fritz, J.

    2016-08-01

    New results of a comprehensive transmission electron microscope (TEM) study including microstructural and chemical analyses of three submicrometer sized, primary PGE metal nuggets in Archean spherule layer material from the Barberton Mountain Land.

  19. X-ray phase and electron microscopic studies of pyrite-phosphate mixtures

    SciTech Connect

    Gerasimov, V.V.; Sheptitskii, S.P.

    1986-06-01

    The reaction in binary pyrite-phosphate mixtures was studied as a function of the temperature of heat treatment by the methods of x-ray phase analysis and scanning electron microscopy. It was found that the phase composition is basically represented by crystalline acid iron phosphate, FeH/sub 3/(PO/sub 4/)/sub 2/.2.5H/sub 2/O, and an amorphous phase in solidification of the composite at 20 C. An increase in the temperature of the heat treatment results in dehydration of the acid iron phosphate with the formation of neutral phosphate with a characteristic hexagonal lattice. Other phosphates also undergo the corresponding transitions.

  20. Central GABAergic innervation of the pituitary in goldfish: a radioautographic and immunocytochemical study at the electron microscope level

    SciTech Connect

    Kah, O.; Dubourg, P.; Martinoli, M.G.; Rabhi, M.; Gonnet, F.; Geffard, M.; Calas, A.

    1987-09-01

    The GABAergic innervation of the goldfish pituitary was studied at the light and electron microscope levels by means of radioautography after in vitro incubation in tritiated gamma-aminobutyric acid (GABA) and immunocytochemistry using antibodies against GABA. Following incubation of pituitary fragments in a medium containing tritiated GABA, a selective uptake of the tracer was observed within the digitations of the neurohypophysis. Silver grain clusters were also observed in the adenohypophyseal tissue. At the electron microscope level, this uptake was found to correspond to nerve endings containing small clear and dense-core vesicles. These labeled profiles were located mainly in neurohypophyseal digitations in close apposition with the basement membrane separating the neurohypophysis from the adenohypophysis. However, they were also encountered in direct contact with most adenohypophyseal cell types in the different lobes. These results were confirmed by immunocytochemical data demonstrating the presence of numerous GABA immunoreactive fibers in both anterior and neurointermediate lobes. They were found either in the digitations of the neurohypophysis or in the adenohypophysis in direct contact with the glandular cells with a distribution and an ultrastructural aspect similar to those observed by radioautography. These data demonstrate that the pituitary of teleosts receives a massive GABAergic innervation. Although physiological data providing a functional significance for such an innervation are lacking, the present study suggests that, as already documented in mammals, GABA may be involved in the neuroendocrine regulation of pituitary functions in teleosts.

  1. Microscopic study on lasing characteristics of the UVSOR storage ring free electron laser

    SciTech Connect

    Hama, H. |; Yamazaki, J.; Kinoshita, T.

    1995-12-31

    Characteristics of storage ring free electron laser (SRFEL) at a short wavelength region (UV and visible) has been studied at the UVSOR facility, Institute for Molecular Science. We have measured the laser power evolution by using a biplanar photodiode, and the micro-macro temporal structure of both the laser and the electron bunch with a dualsweep streak camera. The saturated energy of the laser micropulse in the gain-switching (Q-switching) mode has been measured as a function of the ring current. We have not observed a limitation of the output power yet within the beam current can be stored. We have analyzed the saturated micropulse energy based on a model of gain reduction due to the bunch-heating. The bunch-heating process seems to be very complicate. We derived time dependent gain variations from the shape of macropulse and the bunch length. Those two gain variations are almost consistent with each other but slightly different in detail. The gain may be not only simply reduced by the energy spread but also affected by the phase space rotation due to synchrotron oscillation of the electron bunch. As reported in previous issue, the lasing macropulse consists of a couple of micropulses that are simultaneously evolved. From high resolution two-dimensional spectra taken by the dual-sweep streak camera, we noticed considerable internal substructures of the laser micropulse in both the time distribution and the spectral shape. There are a couple of peaks separated with almost same distance in a optical bunch. Such substructure does not seem to result from statistical fluctuations of laser seeds. Although the origin of the substructure of macropulse is not dear at the present, we are going to discuss about SRFEL properties.

  2. The Sertoli cell of the water buffalo--an electron microscopic study.

    PubMed Central

    Azmi, T I; Bongso, T A; Harisah, M; Basrur, P K

    1990-01-01

    The ultrastructure of Sertoli cells in the seminiferous tubules of water buffaloes before and during sexual maturity was studied by transmission electron microscopy, with emphasis on the intranucleolar vesicular elements. Sertoli cells of animals under 12 months of age were distinguished from the germ cells by the presence of electron dense membrane bound bodies within their cytoplasm. These cells, referred to as basal indifferent supporting cells, were probably involved in the phagocytosis and elimination of degenerating spermatocytes, which failed to differentiate into spermatids and spermatozoa in animals under one year of age. In 12 month old animals, a few Sertoli cells exhibiting the vesicular elements appeared in the nucleolar region while in animals over 15 months of age Sertoli cells could be positively identified by the characteristic cytoplasm containing microtubules, elongated and electron dense mitochondria, extensive granular endoplasmic reticulum and the presence of spermatids in various stages of spermiogenesis. The vesicular elements in the nucleolar region of the Sertoli cells were most prominent at this stage. Ultrastructural features of the Sertoli cells revealed an abundance of ribosome-like particles surrounding the vesicles of varying size. Some of these vesicular elements contained amorphous material suggesting that they represent the products sequestered in the nuclear region for transport to the cytoplasm and that the process of spermiogenesis may be dependent on the ability of Sertoli cells to generate these products at sexual maturity. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. Fig. 8. Fig. 9a. Fig. 9b. Fig. 10. Fig. 11. PMID:2306676

  3. Scanning electron microscopic study of trophozoite and cyst stages of Naegleria fowleri.

    PubMed

    Antonios, Sanaa N

    2010-04-01

    Whole trophozoites and cysts of axenically cultivated Naegleria fowleri were prepared for study of their surface morphology by scanning electron microscopy (SEM). Trophozoites and cyst stages were studied from Chang's culture media. Some trophozoites were examined after animal inoculation and brain isolation to compare the changes in surface features. Photomicrographs of freeze-dried and critical point-dried organisms fixed with glutaraldehyde were presented along with views of both isolates of trophozoites to compare the surface features. SEM revealed the surface of trophozoites to be undulating, wrinkled and covered at irregular intervals by protruding vesicles. There were also surface extensions which were long and thin in brain isolates which may help in the contact and cytolysis of host cells at some distance from the trophozoite. Some cysts appeared wrinkled while others smooth, and empty cysts were also seen with many pores on the surface.

  4. Electron microscopic studies of macrophages in Wallerian degeneration of rat optic nerve after intravenous injection of colloidal carbon.

    PubMed Central

    Ling, E A

    1978-01-01

    The origin of macrophages in the degenerating optic nerve of rats after eye enucleation was investigated electron microscopically following intravenous labelling of mononuclear leucoytes with colloidal carbon. In the various post-operative periods studied carbon-labelled macrophages were seen at the site of lesion. At 4 and 7 days after enucleation carbon-labelled cells were seen at the site of Wallerian degeneration of the optic nerve over 4 mm distal to the site of the lesion. In the electron microscope these cells showed a flattened nucleus bearing coarse chromatin clumps, their cytoplasm contained a prominent Golgi complex and long isolate profiles of rough endoplasmic reticulum. Clusters of carbon particles in the cytoplasms were membrane-bound. Lysosomal bodies embedded with carbon particles were also observed. In relation to the blood vessels of the optic nerve, endothelial cells and pericytes with ingested carbon were seen. Macrophages in the meninges covering the optic nerve were also labelled. The results suggest that some macrophages in the region of Wallerian degeneration in the optic nerve, as well as those at the actual site of the lesion, were transformed blood leucocytes. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 PMID:649492

  5. Designs for a quantum electron microscope.

    PubMed

    Kruit, P; Hobbs, R G; Kim, C-S; Yang, Y; Manfrinato, V R; Hammer, J; Thomas, S; Weber, P; Klopfer, B; Kohstall, C; Juffmann, T; Kasevich, M A; Hommelhoff, P; Berggren, K K

    2016-05-01

    One of the astounding consequences of quantum mechanics is that it allows the detection of a target using an incident probe, with only a low probability of interaction of the probe and the target. This 'quantum weirdness' could be applied in the field of electron microscopy to generate images of beam-sensitive specimens with substantially reduced damage to the specimen. A reduction of beam-induced damage to specimens is especially of great importance if it can enable imaging of biological specimens with atomic resolution. Following a recent suggestion that interaction-free measurements are possible with electrons, we now analyze the difficulties of actually building an atomic resolution interaction-free electron microscope, or "quantum electron microscope". A quantum electron microscope would require a number of unique components not found in conventional transmission electron microscopes. These components include a coherent electron beam-splitter or two-state-coupler, and a resonator structure to allow each electron to interrogate the specimen multiple times, thus supporting high success probabilities for interaction-free detection of the specimen. Different system designs are presented here, which are based on four different choices of two-state-couplers: a thin crystal, a grating mirror, a standing light wave and an electro-dynamical pseudopotential. Challenges for the detailed electron optical design are identified as future directions for development. While it is concluded that it should be possible to build an atomic resolution quantum electron microscope, we have also identified a number of hurdles to the development of such a microscope and further theoretical investigations that will be required to enable a complete interpretation of the images produced by such a microscope.

  6. Designs for a quantum electron microscope.

    PubMed

    Kruit, P; Hobbs, R G; Kim, C-S; Yang, Y; Manfrinato, V R; Hammer, J; Thomas, S; Weber, P; Klopfer, B; Kohstall, C; Juffmann, T; Kasevich, M A; Hommelhoff, P; Berggren, K K

    2016-05-01

    One of the astounding consequences of quantum mechanics is that it allows the detection of a target using an incident probe, with only a low probability of interaction of the probe and the target. This 'quantum weirdness' could be applied in the field of electron microscopy to generate images of beam-sensitive specimens with substantially reduced damage to the specimen. A reduction of beam-induced damage to specimens is especially of great importance if it can enable imaging of biological specimens with atomic resolution. Following a recent suggestion that interaction-free measurements are possible with electrons, we now analyze the difficulties of actually building an atomic resolution interaction-free electron microscope, or "quantum electron microscope". A quantum electron microscope would require a number of unique components not found in conventional transmission electron microscopes. These components include a coherent electron beam-splitter or two-state-coupler, and a resonator structure to allow each electron to interrogate the specimen multiple times, thus supporting high success probabilities for interaction-free detection of the specimen. Different system designs are presented here, which are based on four different choices of two-state-couplers: a thin crystal, a grating mirror, a standing light wave and an electro-dynamical pseudopotential. Challenges for the detailed electron optical design are identified as future directions for development. While it is concluded that it should be possible to build an atomic resolution quantum electron microscope, we have also identified a number of hurdles to the development of such a microscope and further theoretical investigations that will be required to enable a complete interpretation of the images produced by such a microscope. PMID:26998703

  7. [Electron microscopic and morphometric study of the cellular composition of several forms of goiter in man].

    PubMed

    Dmitrieva, N P

    1977-10-01

    According to the ultrastructural patterns four varieties of follicular cells are recognized in the cell population of the human goiter. The parenchyma of different goiters is composed of the same cell types and varieties. Goiters differ in percentages of these cells. The ultrastructure of the main cell form is correlated with the functional activity of the goiter. The "map" of cell composition of some forms of goiter is given, which may be used for a more exact diagnosis of the goiter, especially in the cases of discrepancy between the light microscopical morphological data and clinical picture of the desease. PMID:579702

  8. Solitary fibrous tumor of the inguinal region: a clinicopathological, light-microscopic, immunohistochemical, electron microscopic and flow-cytometric DNA study.

    PubMed

    Cafiero, F; Gipponi, M; Peressini, A; Barabino, P; Queirolo, P; Nicolò, M; Solari, N; Nicolò, G

    2001-01-01

    Solitary fibrous tumors (SFTs) are rare neoplasms with a probable mesenchymal origin that were first reported in the pleura but can occur in different sites. We report a case of SFT arising in the inguinal region of a 55-year-old woman. The patient presented with a mass in the left groin; she underwent wide excision of the lesion which was well-circumscribed and without evidence of adjacent soft tissue involvement. The histological, immunohistochemical and electron microscopic criteria for SFT were found. She had an uneventful recovery and she is alive without evidence of disease five years after operation. To our knowledge, this neoplasm has never been reported in this location.

  9. Human articular cartilage in osteoarthrosis. I. The matrix. Transmission electron microscopic study.

    PubMed

    Montella, A; Manunta, A; Espa, E; Gasparini, G; De Santis, E; Gulisano, M

    1992-01-01

    The present research has been carried out with the aim of contributing to the understanding of morphological changes in human articular cartilage during osteoarthrosis and to evaluate the usefulness of TEM in this application. Only the matrix was examined in this first phase of study. Fragments from the femoral head of 20 patients subjected total hip arthroplasis, were studied by TEM after treatment with current procedures. The images obtained were considered observing the division of cartilage into superficial, intermediate and deep layers. Patients were divided according to the gravity of their clinical conditions. The least severe forms of pathology seem to involve only the superficial layer, which quickly loses the lamina splendens and may be affected by rarefactions of the matrix, which becomes fissured, while the deep layers are only slightly involved. During the later stages, the pathology progresses with irregularity of disposition and size of the collagen fibres and an increase in the number and size of fissures. The intermediate layer shows architectural disorder in the collagen fibres, even reaching the deep layer. The interfibrillar distance appears greater. As pathology progresses, the superficial layer tends to disappear, while the successive layers undergo progressive alteration in disposition and size of the collagen fibres. Globular aggregations of various dimensions and electron density similar to collagen are present in the deep layer. PMID:1288443

  10. Real-time studies of battery electrochemical reactions inside a transmission electron microscope.

    SciTech Connect

    Leung, Kevin; Hudak, Nicholas S.; Liu, Yang; Liu, Xiaohua H.; Fan, Hongyou; Subramanian, Arunkumar; Shaw, Michael J.; Sullivan, John Patrick; Huang, Jian Yu

    2012-01-01

    We report the development of new experimental capabilities and ab initio modeling for real-time studies of Li-ion battery electrochemical reactions. We developed three capabilities for in-situ transmission electron microscopy (TEM) studies: a capability that uses a nanomanipulator inside the TEM to assemble electrochemical cells with ionic liquid or solid state electrolytes, a capability that uses on-chip assembly of battery components on to TEM-compatible multi-electrode arrays, and a capability that uses a TEM-compatible sealed electrochemical cell that we developed for performing in-situ TEM using volatile battery electrolytes. These capabilities were used to understand lithiation mechanisms in nanoscale battery materials, including SnO{sub 2}, Si, Ge, Al, ZnO, and MnO{sub 2}. The modeling approaches used ab initio molecular dynamics to understand early stages of ethylene carbonate reduction on lithiated-graphite and lithium surfaces and constrained density functional theory to understand ethylene carbonate reduction on passivated electrode surfaces.

  11. Electron microscopical study on impaired phagocytic function of granulocytes in diabetics.

    PubMed

    Shimizu, S; Shimizu, M; Hoshi, K; Kato, T; Sano, T; Sasaki, Y; Someya, K

    1982-01-01

    Phagocytic ability of granulocytes obtained from 22 diabetic patients was studied by electron microscopy in order to explain their susceptibility to infection and was compared with that of granulocytes from 13 healthy controls. The main features of the procedure employed in this study were as follows; (1) morphologically quantitative assessment of phagocytosis, (2) no separate assay of engulfment and killing of bacteria, (3) granulocytes were mixed with 10 times their number of bacteria, (4) antibiotics were not used to kill extracellular bacteria, (5) use of a conic tube lined with collodion film for cell pellet formation, (6) each conic tube contained less than 1 X 10(6) granulocytes, (7) sections examined were the vertically cut surfaces of the thin buffy coat. Control subjects showed that most granulocytes did not contain intact intracellular bacteria. Assay of aliquots sampled after 30 minutes and 2 hours in controls showed no significant difference. However, in diabetics, eight cases showed similar results with controls and were thought to have normal function, and fourteen cases showed the increased number of granulocytes containing intact intracellular bacteria was much more marked in aliquots sampled after 2 hours and were considered as showing various degrees of impaired bactericidal ability.

  12. Electron microscope studies. Progress report, 1 July 1990--1 June 1991

    SciTech Connect

    Crewe, A.V.; Kapp, O.H.

    1991-06-01

    This year our laboratory has continued to make progress in the design of electron-optical systems, in the study of structure-function relationships of large multi-subunit proteins, in the development of new image processing software and in achieving a workable sub-angstrom STEM. We present an algebraic approach to the symmetrical Einzel (unipotential) lens wherein we simplify the analysis by specifying a field shape that meets some preferred set of boundary or other conditions and then calculate the fields. In a second study we generalize this approach to study of three element electrostatic lenses of which the symmetrical Einzel lens is a particular form. The purpose is to develop a method for assisting in the design of a lens for a particular purpose. In our biological work we study a stable and functional dodecameric complex of globin chains from the hemoglobin of Lumbricus terrestris. This is a complex lacking the ``linker`` subunit first imaged in this lab and required for maintenance of the native structure. In addition, we do a complete work-up on the hemoglobin of the marine polychaete Eudistylia vancouverii demonstrating the presence of a hierarchy of globin complexes. We demonstrate stable field-emission in the sub-angstrom STEM and the preliminary alignment of the beam. We continue our exploration of a algorithms for alignment of sequences of protein and DNA. Our computer facilities now include four second generation RISC workstations and we continue to take increasing advantage of the floating-point and graphical performance of these devices.

  13. Type II pneumocytes in mixed cell culture of human lung: a light and electron microscopic study.

    PubMed Central

    Bingle, L; Bull, T B; Fox, B; Guz, A; Richards, R J; Tetley, T D

    1990-01-01

    Alveolar Type II epithelial cells dedifferentiate rapidly in vitro. Studies with animal tissue suggest that cell-cell and extracellular matrix-cell interactions are important in the retention of Type II cell morphology in vitro. Thus, in this study with human tissue, alveolar Type II cells, alveolar macrophages, and spindle cells were prepared from the same sample of lung (obtained following lobectomy for cancer, n = 3), cocultured on glass cover slips or tissue culture plastic, and studied by light microscopy with scanning (SEM) and transmission (TEM) electron microscopy for 8 days. The primary cell isolates contained approximately 45% Type II cells; the remainder were macrophages or unidentifiable cells. Clusters, made up of a single layer of cuboidal Type II cells around a central core of connective tissue (largely collagen and some elastic tissue), formed above a monolayer of spindle cells. The Type II cells were morphologically similar to those seen in vivo. The cells were still cuboidal at 8 days but had lost their lamellar bodies, which were released into the medium via the apical surface. The clusters increased in size with time (area, microns 2: day 1, 29(5-143) x 10(2); day 8, 63(10-311) x 10(2); mean(range); p less than 0.02) without changing in number per culture, suggesting Type II cell proliferation. This may have been due to factors produced by the other cells and adherence to the extracellular matrix (ECM); (free collagen fibers, present in the original preparation, spindle cells, and/or Type II cells could be responsible for presence of ECM). We propose this as a useful model for the study of human Type II epithelial cells in vitro. Images FIGURE 1. a FIGURE 1. b FIGURE 1. c FIGURE 1. d FIGURE 1. e FIGURE 1. f FIGURE 2. a FIGURE 2. b FIGURE 2. c FIGURE 2. d FIGURE 2. e FIGURE 2. f FIGURE 2. g FIGURE 3. PMID:2384069

  14. Scanning electron microscopic study of flowing erythrocytes in hepatic sinusoids as revealed by 'in vivo cryotechnique'.

    PubMed

    Terada, N; Kato, Y; Fuji, Y; Ueda, H; Baba, T; Ohno, S

    1998-01-01

    The purpose of this study is to develop a method for stabilizing erythrocytes under flowing condition in living livers, as revealed by scanning electron microscopy (SEM). After the procedure of the 'in vivo cryotechnique', both freeze-substitution and subsequent t-butyl alcohol freeze-drying methods were used for preparing SEM specimens. By freeze-fracturing with a scalpel in liquid nitrogen before the freeze-substitution, better preserved surface tissues were obtained for examination. Erythrocytes in hepatic sinusoids were clearly detected without plasma components by the freeze-substitution method, and well preserved in parts where they were flowing with their original shapes. Some were accumulated in sinusoids, especially injunctioning areas of sinusoidal networks, as compared with those in narrow lumens between hepatocyte plates. Shapes of such erythrocytes were various, locating along endothelial cells. After stopping the blood supply into livers by artificial cardiac arrest, their shapes were dramatically changed into biconcaves and they became aggregated side by side to be packed in the sinusoids. The three-dimensional shapes of flowing erythrocytes in hepatic sinusoids were demonstrated for the first time by the 'in vivo cryotechnique' combined with SEM. PMID:9602528

  15. Retinal and vitreal neovascularization in retinopathy of prematurity. A scanning electron microscopic study in the kitten.

    PubMed

    Yoneya, S; Tso, M O

    1991-12-01

    The angioarchitecture of vitreal and retinal neovascularizations produced experimentally in the eyes of kittens aged 2 to 9 weeks was studied with scanning electron microscopy. Various forms of new retinal and vitreal vessels were observed depending on topographic locations. Intraretinal neovascularization was observed at the retinal periphery as it grew toward the avascular zone in forms of short vascular buds, aneurysmal outgrowths, and neovascular loops. Posterior or to this frond of neovascularization, intertwining intraretinal telangiectasia was observed. At the posterior pole, capillaries with microaneurysms extended posteriorly toward the deeper layers of the retina from the vascular trunks at the nerve fiber layer. Vitreal neovascularization broke through the internal limiting membrane and exhibited aneurysmal outgrowths, clusters of glomerular swellings, and sinusoidal vascular channels. At the optic disc, vitreous neovascularization took the form of aneurysmal outgrowths and long vascular buds. Vitreal neovascularization showed different characteristics from the intraretinal neovascularization. We hypothesize that the topographic variation of the angioarchitecture of retinal and vitreal neovascularizations depends on the maturity of the vessels and might be related to the hemodynamics at each site. PMID:1726774

  16. Transmission electron microscope study of dislocations in orthopyroxene (Mg, Fe)2Si2O6

    NASA Astrophysics Data System (ADS)

    van Duysen, J. C.; Doukhan, N.; Doukhan, J. C.

    1985-02-01

    The orthopyroxene crystal structure can be viewed as the stacking of alternating tetrahedral and octahedral layers parallel to the (100) plane. Easy glide occurs in the (100) plane at the level of the octahedral layer to prevent breakage of the strong Si-O bonds. Dislocations with c and b Burgers vectors have been activated in (100) by room temperature indentation in an orthoenstatite gem quality single crystal. Investigations in transmission electron microscopy show that the b dislocations ( b≃9 Å) are not dissociated while the c's ( c=5.24 Å) are dissociated into four partials. This result is interpreted by considering the oxygen sublattice as a distorted FCC one. The four c partials are thus Shockley partials bounding three stacking faults. For the two outer ones, synchroshear of the cations is necessary to keep unchanged their sixfold coordination; the oxygen sublattice is locally transformed into a HCP lattice. This accounts for the observed low splitting (≃100 Å) of these faults as compared to the median one (≃500 Å) which does not affect the oxygen sublattice and does not require cation synchroshear. In a Fe rich orthopyroxene (eulite), semi coherent exsolution lamellae have been studied. Either only c edge dislocations or both b and c edge dislocations occur in the phase boundaries depending upon the thickness of the lamellae. Only the c dislocations are dissociated. From the observed spacing between these mismatch dislocations a crude estimate of the exsolution temperature is proposed T ex ≃ 700° C.

  17. A light, transmission and scanning electron microscope study of snuff-treated hamster cheek pouch epithelium.

    PubMed

    Ashrafi, S H; Das, A; Worowongvasu, R; Mehdinejad, B; Waterhouse, J P

    1992-03-01

    The effects of smokeless tobacco (snuff) on hamster cheek mucosa were studied by light microscopy, transmission (TEM) and scanning electron microscopy (SEM). Two grams of commercially available smokeless tobacco were placed into the blind end of the right cheek pouch of each experimental animal, once a day and five days a week for 24 months. The control animals did not receive smokeless tobacco. After 24 months treatment with smokeless tobacco, hamster cheek mucosal epithelium lost its translucency and had become whitish in color. By light microscopy hyperorthokeratosis, prominent granular cell layers with increased keratohyalin granules and hyperplasia were seen. At the ultrastructural level, wider intercellular spaces filled with microvilli, numerous shorter desmosomes, many thin tonofilament bundles, increased number of mitochondria, membrane coating granules and keratohyalin granules were seen in snuff-treated epithelium. The changes in the surface of the epithelium as seen by SEM were the development of an irregular arrangement of the microridges and the disappearance of the normal honeycomb pattern. The microridges were irregular, widened and surrounded the irregular elongated pits. Some smooth areas without microridges and pits were also seen. The long-term histological, TEM and SEM changes induced by smokeless tobacco treatment of the epithelium are well correlated with each other and were similar to those reported in human leukoplakia without dyskeratosis. They imply changes of pathological response resulting from topically applied snuff.

  18. A SCANNING ELECTRON MICROSCOPIC STUDY OF THE PATTERNS OF EXTERNAL ROOT RESORPTION UNDER DIFFERENT CONDITIONS

    PubMed Central

    Sreeja, Ravindran; Minal, Chaudhary; Madhuri, Tumsare; Swati, Patil; Vijay, Wadhwan

    2009-01-01

    Objective: The aim of this study was to examine if there are qualitative differences in the appearance of external root resorption patterns of primary teeth undergoing physiologic resorption and permanent teeth undergoing pathological root resorption in different conditions. Material and Methods: A total of 40 teeth undergoing external root resorption in different conditions were divided into 4 groups and prepared for examination under scanning electron microscopy at magnifications ranging from 20x to 1000x. Group I: 10 primary molars exfoliated due to physiologic root resorption; Group II: 10 permanent teeth with periapical granulomas showing signs of resorption; Group III:10 permanent teeth therapeutically extracted during the course of orthodontic therapy with evidence of resorption, and Group IV: 10 permanent teeth associated with odontogenic tumors that showed evidence of resorption. Results: In Group I, the primary teeth undergoing resorption showed smooth extensive and predominantly regular areas reflecting the slow ongoing physiologic process. In Group II, the teeth with periapical granulomas showed the resorption was localized to apex with a funnel shaped appearance in most cases. Teeth in Group III, which had been subjected to a short period of light orthodontic force, showed the presence of numerous resorption craters with adjoining areas of cemental repair in some cases. Teeth associated with odontogenic tumors in Group IV showed many variations in the patterns of resorption with extensive loss of root length and a sharp cut appearance of the root in most cases. Conclusion: Differences were observed in the patterns of external root resorption among the studied groups of primary and permanent teeth under physiologic and pathological conditions. PMID:19936530

  19. Scanning Electron Microscopic study of Piper betle L. leaves extract effect against Streptococcus mutans ATCC 25175

    PubMed Central

    RAHIM, Zubaidah Haji Abdul; THURAIRAJAH, Nalina

    2011-01-01

    Introduction Previous studies have shown that Piper betle L. leaves extract inhibits the adherence of Streptococcus mutans to glass surface, suggesting its potential role in controlling dental plaque development. Objectives: In this study, the effect of the Piper betle L. extract towards S. mutans (with/without sucrose) using scanning electron microscopy (SEM) and on partially purified cell-associated glucosyltransferase activity were determined. Material and Methods S. mutans were allowed to adhere to glass beads suspended in 6 different Brain Heart Infusion broths [without sucrose; with sucrose; without sucrose containing the extract (2 mg mL-1 and 4 mg mL-1); with sucrose containing the extract (2 mg mL-1 and 4 mg mL-1)]. Positive control was 0.12% chlorhexidine. The glass beads were later processed for SEM viewing. Cell surface area and appearance and, cell population of S. mutans adhering to the glass beads were determined upon viewing using the SEM. The glucosyltransferase activity (with/without extract) was also determined. One- and two-way ANOVA were used accordingly. Results It was found that sucrose increased adherence and cell surface area of S. mutans (p<0.001). S. mutans adhering to 100 µm2 glass surfaces (with/without sucrose) exhibited reduced cell surface area, fluffy extracellular appearance and cell population in the presence of the Piper betle L. leaves extract. It was also found that the extract inhibited glucosyltransferase activity and its inhibition at 2.5 mg mL-1 corresponded to that of 0.12% chlorhexidine. At 4 mg mL-1 of the extract, the glucosyltransferase activity was undetectable and despite that, bacterial cells still demonstrated adherence capacity. Conclusion The SEM analysis confirmed the inhibitory effects of the Piper betle L. leaves extract towards cell adherence, cell growth and extracellular polysaccharide formation of S. mutans visually. In bacterial cell adherence, other factors besides glucosyltransferase are involved. PMID

  20. [Electron microscopic detection rate of enteral viruses in diarrhea of dogs, cats, calves, swine and foals in the year 1988--electron microscopic study results].

    PubMed

    Biermann, U; Herbst, W; Krauss, H; Schliesser, T

    1989-12-01

    During 1988 fecal and gut samples of 641 dogs, 198 cats, 576 calves, 108 piglets and 64 foals with diarrhoea were investigated for virus infections by electron microscopy. In samples of dogs and cats parvovirus was detected at a proportion of 21.9% and 16.7%, respectively; rotavirus alone or together with coronavirus was found only in 0.3-1.5% of the specimens. In samples of calves rotavirus, as well as coronavirus dominated with a detection rate amounting to 17.4% and 26.6% respectively (including 4.5% of mixed infections); parvovirus was present in a ratio of 0.5%. Specimens of piglets mainly contained coronavirus (25.0%), and in lower percentages rotavirus (2.8%), rota- and coronaviruses (0.9%) and parvovirus (0.9%). In feces of foals rotavirus was detected in 6.3% and particles resembling picornavirus in 4.7% of cases. Not identifiable virus particles resembling corona-or picornaviruses were rarely found (between 0.6-2.5) also in specimens of the other animal species. PMID:2513799

  1. Uptake and processing of (/sup 3/H)retinoids in rat liver studied by electron microscopic autoradiography

    SciTech Connect

    Hendriks, H.F.; Elhanany, E.; Brouwer, A.; de Leeuw, A.M.; Knook, D.L.

    1988-03-01

    The role of rat liver cell organelles in retinoid uptake and processing was studied by electron microscopic autoradiography. (/sup 3/H)Retinoids were administered either orally, to make an inventory of the cell organelles involved, or intravenously as chylomicron remnant constituents to study retinoid processing by the liver with time. No qualitative differences were observed between the two routes of administration. Time-related changes in the distribution of grains were studied using chylomicron remnant (/sup 3/H)retinoids. The percentages of grains observed over cells and the space of Disse at 5 and 30 min after administration were, respectively: parenchymal cells, 72.6 and 70.4%; fat-storing cells, 5.0 and 18.1%, and the space of Disse, 14.4 and 8.9%. Low numbers of grains were observed over endothelial and Kupffer cells. The percentages of grains observed over parenchymal cell organelles were, respectively: sinusoidal area, 59.6 and 34.4%; smooth endoplasmic reticulum associated with glycogen, 13.8 and 13.4%; mitochondria, 5.4 and 13.6%; rough endoplasmic reticulum, 4.2 and 7.3%, and rough endoplasmic reticulum associated with mitochondria, 3.7 and 6.5%. It is concluded that chylomicron remnant (/sup 3/H)retinoids in combination with electron microscopic autoradiography provide a good system to study the liver processing of retinoids in vivo. These results, obtained in the intact liver under physiological conditions, further substantiate that retinoids are processed through parenchymal cells before storage occurs in fat-storing cell lipid droplets, that retinoid uptake is not mediated through lysosomes and that the endoplasmic reticulum is a major organelle in retinoid processing.

  2. Zinc deficiency in the 11 day rat embryo: a scanning and transmission electron microscope study

    SciTech Connect

    Harding, A.J.; Dreosti, I.E.; Tulsi, R.S.

    1988-01-01

    Zinc deficient rat embryos were obtained on the 11th day of pregnancy and examined by scanning and transmission electron microscopy. Scanning electron microscopy revealed an increase in the number of deformed embryos, as well as embryonic growth retardation. In addition, the epithelium of zinc deficient embryos displayed a marked increase in surface microvilli, as well as the presence of blebbing. Transmission electron microscopy indicated extensive cell death in the neural epithelium which was apparently more severely damaged by zinc deficiency than were mesenchymal cells. Mitochondrial cristae were affected to a greater degree than any other membrane of the cell and cristael disintegration appeared to represent the principal cellular lesion preceding necrosis of neural cells and neural tube teratology. 29 references, 4 figures, 1 table.

  3. Scanning electron microscopic study of the effects of pressure on the luminal surface of the rabbit aorta.

    PubMed

    Swinehart, P A; Bentley, D L; Kardong, K V

    1976-01-01

    The effects of pressure on the luminal surface of the rabbit aorta were investigated using the scanning electron microscope. The method followed was perfusion under hydrostatic pressure of a section of thoracic aorta, in vitro. The characteristic ridged pattern seen in sections fixed at zero hydrostatic pressure was to a large extent eliminated when fixation occurred at pressures equivalent to those experienced by the aorta at systole or diastole. This study suggests that the spiral ridged pattern is dependent upon the fixation pressure and may not be present in a normally functioning artery. Any attempts to characterize or interpret the appearance of the luminal arterial wall must take into account the effects of pressure.

  4. Mammillary Bodies in Alzheimer's Disease: A Golgi and Electron Microscope Study.

    PubMed

    Baloyannis, Stavros J; Mavroudis, Ioannis; Baloyannis, Ioannis S; Costa, Vassiliki G

    2016-05-01

    Alzheimer's disease (AD) is a progressive neurodegenerative disorder, characterized by irreversible memory decline, concerning no rarely spatial memory and orientation, alterations of the mood and personality, gradual loss of motor skills, and substantial loss of capacities obtained by previous long education. We attempted to describe the morphological findings of the mammillary bodies in early cases of AD. Samples were processed for electron microscopy and silver impregnation techniques. The nuclei of the mammillary bodies demonstrated a substantial decrease in the neuronal population and marked abbreviation of dendritic arbors. Decrease in spine density and morphological abnormalities of dendritic spines was also seen. Synaptic alterations were prominent. Alzheimer's pathology, such as deposits of amyloid-β peptide and neurofibrillary degeneration, was minimal. Electron microscopy revealed mitochondrial alterations and fragmentation of Golgi apparatus, associated frequently with synaptic pathology. PMID:26399484

  5. The heterogeneous composition of working place aerosols in a nickel refinery: a transmission and scanning electron microscope study.

    PubMed

    Weinbruch, Stephan; van Aken, Peter; Ebert, Martin; Thomassen, Yngvar; Skogstad, Asbjørn; Chashchin, Valery P; Nikonov, Alexander

    2002-06-01

    Size, morphology and chemical composition of individual aerosol particles collected in a nickel refinery were analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis (EDX). The phase composition was determined by selected area electron diffraction and EDX in a transmission electron microscope. Most particles are heterogeneous on a nanometer scale and consist of various phases. Nickel phases observed in the roasting and anode casting departments include metallic nickel, bunsenite (NiO), trevorite (Ni,Cu)Fe2O4, heazlewoodite Ni3S2, godlevskite (Ni,Cu)9S8, orthorhombic NiSO4 and an amorphous Ni,Cu.Al,Pb sulfate of variable composition. Additional phases encountered include corundum (Al2O3), murdochite (PbCu6O8), hexagonal Na2SO4, anhydrite (CaSO4), graphite (C) and amorphous carbon. The implications of the occurrence of the different Ni phases and their nanometer size for the study of adverse health effects are explored. PMID:12094927

  6. Comparative evaluation of NovaMin desensitizer and Gluma desensitizer on dentinal tubule occlusion: a scanning electron microscopic study

    PubMed Central

    Joshi, Surabhi; Gowda, Ashwini Shivananje

    2013-01-01

    Purpose In this study, the effect of calcium sodium phosphosilicate (NovaMin) desensitizing agent, which is a powder-based system, and hydroxyethyl methacrylate and glutaraldehyde (Gluma desensitizer), which is liquid-based system, on dentinal tubule occlusion was analyzed by scanning electron microscope. The effects of the above two along with one control group were compared to determine the more effective method of sealing the dentinal tubules after initial application. Methods Twenty specimens were allocated to each of 3 groups: Control, Gluma desensitizer, and NovaMin. Two additional samples were also prepared and treated with Gluma and NovaMin; these samples were longitudinally fractured. The specimens were prepared from extracted sound human premolars and were stored in 10% formalin at room temperature. The teeth were cleaned of gross debris and then sectioned to provide one to two dentin specimens. The dentin specimens were etched with 6% citric acid for 2 minutes and rinsed in distilled water. Control discs were dried, and the test discs were treated with the desensitizing agents as per the manufacturer's instructions. The discs as well as longitudinal sections were later analyzed under the scanning electron microscope. The proportions of completely occluded, partially occluded, and open tubules within each group were calculated. The ratios of completely and partially occluded tubules to the total tubules for all the groups was determined, and the data was statistically analyzed using nonparametric tests and statistical significance was calculated. Results NovaMin showed more completely occluded tubules (0.545±0.051) while Gluma desensitizer showed more partially occluded tubules (0.532±0.075). The differences among all the groups were statistically significant (P≤ 0.05). Conclusion Both materials were effective in occluding dentinal tubules but NovaMin appeared more promising in occluding tubules completely after initial application. PMID:24455439

  7. Metal particle emissions in the exhaust stream of diesel engines: an electron microscope study.

    PubMed

    Liati, Anthi; Schreiber, Daniel; Dimopoulos Eggenschwiler, Panayotis; Arroyo Rojas Dasilva, Yadira

    2013-12-17

    Scanning electron microscopy and transmission electron microscopy were applied to investigate the morphology, mode of occurrence and chemical composition of metal particles (diesel ash) in the exhaust stream of a small truck outfitted with a typical after-treatment system (a diesel oxidation catalyst (DOC) and a downstream diesel particulate filter (DPF)). Ash consists of Ca-Zn-P-Mg-S-Na-Al-K-phases (lube-oil related), Fe, Cr, Ni, Sn, Pb, Sn (engine wear), and Pd (DOC coating). Soot agglomerates of variable sizes (<0.5-5 μm) are abundant upstream of the DPF and are ash-free or contain notably little attached ash. Post-DPF soot agglomerates are very few, typically large (>1-5 μm, exceptionally 13 μm), rarely <0.5 μm, and contain abundant ash carried mostly from inside the DPF. The ash that reaches the atmosphere also occurs as separate aggregates ca. 0.2-2 μm in size consisting of sintered primary phases, ca. 20-400 nm large. Insoluble particles of these sizes may harm the respiratory and cardiovascular systems. The DPF probably promotes breakout of large soot agglomerates (mostly ash-bearing) by favoring sintering. Noble metals detached from the DOC coating may reach the ambient air. Finally, very few agglomerates of Fe-oxide nanoparticles form newly from engine wear and escape into the atmosphere. PMID:24274188

  8. Metal particle emissions in the exhaust stream of diesel engines: an electron microscope study.

    PubMed

    Liati, Anthi; Schreiber, Daniel; Dimopoulos Eggenschwiler, Panayotis; Arroyo Rojas Dasilva, Yadira

    2013-12-17

    Scanning electron microscopy and transmission electron microscopy were applied to investigate the morphology, mode of occurrence and chemical composition of metal particles (diesel ash) in the exhaust stream of a small truck outfitted with a typical after-treatment system (a diesel oxidation catalyst (DOC) and a downstream diesel particulate filter (DPF)). Ash consists of Ca-Zn-P-Mg-S-Na-Al-K-phases (lube-oil related), Fe, Cr, Ni, Sn, Pb, Sn (engine wear), and Pd (DOC coating). Soot agglomerates of variable sizes (<0.5-5 μm) are abundant upstream of the DPF and are ash-free or contain notably little attached ash. Post-DPF soot agglomerates are very few, typically large (>1-5 μm, exceptionally 13 μm), rarely <0.5 μm, and contain abundant ash carried mostly from inside the DPF. The ash that reaches the atmosphere also occurs as separate aggregates ca. 0.2-2 μm in size consisting of sintered primary phases, ca. 20-400 nm large. Insoluble particles of these sizes may harm the respiratory and cardiovascular systems. The DPF probably promotes breakout of large soot agglomerates (mostly ash-bearing) by favoring sintering. Noble metals detached from the DOC coating may reach the ambient air. Finally, very few agglomerates of Fe-oxide nanoparticles form newly from engine wear and escape into the atmosphere.

  9. Electron microscope studies of glutamic oxalacetic transaminase in rat liver cell.

    PubMed

    Lee, S H; Torack, R M

    1968-12-01

    Liver tissue of the rat, fixed in glutaraldehyde and formaldehyde, was incubated in a medium which consisted of 20 mML-aspartic acid, 2 mM alpha-ketoglutaric acid, 50 mM imidazole and 6 mM lead nitrate at pH 7.2-7.4. The electron-opaque precipitates, due to glutamic oxalacetic transaminase activity in liver cells, were found to be localized to the cristae and surface membranes of the mitochondria, the limiting membrane of the microbodies, and the nuclear membrane. Sucrose storage and trauma resulted in altered morphology and diminished final product intensity in mitochondria, but the microbody enzyme activity disappeared completely under these conditions. These distinctive responses of enzymatic activity are considered to indicate a difference in either the enzyme protein or its membrane attachment to these two sites. The use of a buffered dehydrating ethanol series to prepare tissue blocks for electron microscopy appeared to result in more precise intracellular localization of enzymatic reaction product.

  10. Secretory organelles in ECL cells of the rat stomach: an immunohistochemical and electron-microscopic study.

    PubMed

    Zhao, C M; Chen, D; Lintunen, M; Panula, P; Håkanson, R

    1999-12-01

    ECL cells are numerous in the rat stomach. They produce and store histamine and chromogranin-A (CGA)-derived peptides such as pancreastatin and respond to gastrin with secretion of these products. Numerous electron-lucent vesicles of varying size and a few small, dense-cored granules are found in the cytoplasm. Using confocal and electron microscopy, we examined these organelles and their metamorphosis as they underwent intracellular transport from the Golgi area to the cell periphery. ECL-cell histamine was found to occur in both cytosol and secretory vesicles. Histidine decarboxylase, the histamine-forming enzyme, was in the cytosol, while pancreastatin (and possibly other peptide products) was confined to the dense cores of granules and secretory vesicles. Dense-cored granules and small, clear microvesicles were more numerous in the Golgi area than in the docking zone, i.e. close to the plasma membrane. Secretory vesicles were numerous in both Golgi area and docking zone, where they were sometimes seen to be attached to the plasma membrane. Upon acute gastrin stimulation, histamine was mobilized and the compartment size (volume density) of secretory vesicles in the docking zone was decreased, while the compartment size of microvesicles was increased. Based on these findings, we propose the following life cycle of secretory organelles in ECL cells: small, electron-lucent microvesicles (pro-granules) bud off the trans Golgi network, carrying proteins and secretory peptide precursors (such as CGA and an anticipated prohormone). They are transformed into dense-cored granules (approximate profile diameter 100 nm) while still in the trans Golgi area. Pro-granules and granules accumulate histamine, which leads to their metamorphosis into dense-cored secretory vesicles. In the Golgi area the secretory vesicles have an approximate profile diameter of 150 nm. By the time they reach their destination in the docking zone, their profile diameter is between 200 and 500 nm

  11. Electron microscopic study of the cortical reaction in eggs of the starfish (Patria miniata).

    PubMed

    Holland, N D

    1980-01-01

    The egg coats of a starfish (Patiria miniata) are examined before, during, and after the cortical reaction by scanning and transmission electron microscopy. The unfertilized egg is closely invested by a vitelline coat about 300 micron thick, and cortical granules are scattered in the peripheral cytoplasm. After insemination, as the cortical granules undergo exocytosis, the cortical reaction sweeps over the egg surface. Much of the material ejected from the cortical granules adheres to the inner surface of the vitelline coat as a dense layer about 40 micron thick and as scattered spheres and hemispheres, each about 1 micron in diameter. Together, the vitelline coat and the adherent cortical granule material form the fertilization envelope, which becomes separated from the plasma membrane of the egg by a perivitelline space. The perivitelline space contains some flocculent material, which is too diffuse and discontinuous to be considered a hyaline layer. Possible functions of the starfish egg coats are discussed.

  12. Light and Electron Microscopic Studies of Microorganisms Growing in Rotating Biological Contactor Biofilms

    PubMed Central

    Kinner, Nancy E.; Balkwill, David L.; Bishop, Paul L.

    1983-01-01

    The biofilms growing in the first compartments of two rotating biological contactors used to treat municipal wastewater were examined by light and electron microscopy. The biofilms were found to contain a complex and varied microbial community that included filamentous and unicellular bacteria, protozoa, metazoa, and (possibly) bacteriophage. The predominant microorganism among these appeared to be a filamentous bacterium that was identical to Sphaerotilus in both morphological and ultrastructural characteristics. It was possible to isolate a Sphaerotilus-like bacterium from each contactor. Both the Sphaerotilus filaments and the wide variety of unicellular bacteria present tended to contain poly-β-hydroxybutyrate inclusions, a probable indication that these organisms were removing carbon from the wastewater and storing it. The microbial population of the biofilms appeared to be metabolically active, as evidenced by the presence of microcolonies and dividing cells. Images PMID:16346299

  13. Endothelial contraction induced by histamine-type mediators: an electron microscopic study.

    PubMed

    Majno, G; Shea, S M; Leventhal, M

    1969-09-01

    Previous work has shown that endogenous chemical mediators, of which histamine is the prototype, increase the permeability of blood vessels by causing gaps to appear between endothelial cells. In the present paper, morphologic and statistical evidence is presented, to suggest that endothelial cells contract under the influence of mediators, and that this contraction causes the formation of intercellular gaps. Histamine, serotonin, and bradykinin were injected subcutaneously into the scrotum of the rat, and the vessels of the underlying cremaster muscle were examined by electron microscopy. To eliminate the vascular collapse induced by routine fixation, in one series of animals (including controls) the root of the cremaster was constricted for 2-4 min prior to sacrifice, and the tissues were fixed under conditions of mild venous congestion. Electron micrographs were taken of 599 nuclei from the endothelium of small blood vessels representing the various experimental situations. Nuclear deformations were classified into four types of increasing tightness (notches, foldsl closing folds, and pinches. In the latter the apposed surfaces of the nuclear membrane are in contact). It was found that: (1) venous congestion tends to straighten the nuclei in al groups; (2) mediators cause a highly significant increase in the number of pinches (P < 0.001), also if the vessels are distended by venous congestion; (3) fixation without venous congestion causes vascular collapse. The degree of endothelial recoil, as measured by nuclear pinches, is very different from that caused by mediators (P < 0.001). (4) Pinched nuclei are more frequent in leaking vessels, and in cells adjacent to gaps (P < 0.001); (5) mediators also induce, in the endothelium, cytoplasmic changes suggestive of contraction, and similar to those of contracted smooth muscle; (6) there is no evidence of pericyte contraction under the conditions tested. Occasional pericytes appeared to receive fine nerve endings

  14. Development of high-brightness ultrafast electron microscope for studying nanoscale dynamics associated with strongly correlated materials

    NASA Astrophysics Data System (ADS)

    Tao, Zhensheng

    investigations. The reduction of the optical spectral weight and the anisotropic phononic response is revealed by the UED measurements in the noncooperative phase-transition region, suggesting intriguing interplay between the Mott-Hubbard correlated electrons and the Peierls lattice distortion. The first-generation UED system is found to be limited by its brightness when high spatiotemporal resolution is required for the studies on nanometer-scale materials. The major constrain on the brightness is the space charge effect, which affects the phase space of the electron pulses. Using the projection-shadow-image technique, the space charge effects in the near-cathode-surface region are investigated. The results suggest a strong space-charge-led perturbation on the electrons' spatial and momentum distributions in the early stage of the short-pulse generation, and the performance with possible corrections in the drift region is discussed under the framework of a mean-field theory. In laboratory, a radio-frequency (RF) cavity is implemented as a longitudinal focusing lens in the ultrafast electron microscope (UEM). The RF compression together with several magnetic lenses in the beam path, reshapes the electrons' phase space to achieve high brightness and high temporal resolution at the same time. High precision phase-lock between the electron pulses and the RF electric field timing is achieved by implementing a low-level RF phase-locked loop (PLL), an RF-amplifier station and a cavity PLL. The details of these RF systems are introduced, with characterization results presented. The RF-compression UEM is preliminarily characterized, which demonstrates the feasibility of using RF compression to generate high-brightness electron pulses. Future improvements and prospects for the system are also discussed.

  15. Inhibition of Sindbis Virus Release by Media of Low Ionic Strength: an Electron Microscope Study

    PubMed Central

    Waite, Marilynn R. F.; Brown, Dennis T.; Pfefferkorn, Elmer R.

    1972-01-01

    Release of Sindbis virus from infected cells is inhibited by lowering the ionic strength of the medium. To determine the nature of the inhibited step, we examined, by electron microscopy, both freeze-etched and thin-sectioned preparations which had been fixed with either glutaraldehyde or formaldehyde. Inhibitory medium had two different effects on Sindbis virus release: virus budding was partially inhibited, and those virions which did mature were precipitated on the surface of the cell. Freeze-etched, inhibited cells showed very few viral buds. After shift to normal medium, the number of budding virions increased dramatically, far exceeding the quantity found in normal controls. Thus, low ionic strength medium clearly inhibited an early stage of virus maturation. The results were the same regardless of the fixative. Thin sections of glutaraldehyde-fixed, inhibited cells contained large extracellular aggregates of mature virus which were not present in similar, formaldehyde-fixed preparations. Fixation of radioactively-labeled, inhibited cultures revealed that approximately half of the virus that could be released from inhibited cells by raising the ionic strength of the medium could also be released by formaldehyde, but not by glutaraldehyde. This fraction probably represents mature virus attached to the cell surface by the ionic conditions. Images PMID:4672394

  16. Cytoarchitecture of Caudiverbera caudiverbera stage VI oocytes: a light and electron microscope study.

    PubMed

    Dabiké, M; Preller, A

    1999-06-01

    The general characteristics and salient features of the full-grown stage VI Caudiverbera caudiverbera oocyte at the light and electron microscopy level are described. The oocyte is a huge cell with radial symmetry and distinct polarity. A black animal hemisphere, rich in pigment granules and containing the nucleus, is clearly distinguished from the unpigmented white-yellowish vegetal hemisphere. The cell is surrounded by a highly invaginated plasma membrane, with numerous microvilli. The cortex underlying the plasma membrane contains cortical and pigment granules, mitochondria, rough endoplasmic reticulum and coated vesicles. Cytoskeletal components, such as actin filaments and microtubules, are also found in this region. The predominant structures, distributed throughout the cell, are the yolk platelets, which show a gradient in size with small platelets in the animal half and very large ones in the vegetal zone. Mitochondria are also very abundant in both hemispheres and clouds of these organelles are found in the perinuclear region, frequently associated with microtubules. Developed Golgi complexes are present in the cytoplasm and occasionally, annulate lamellae appear towards the inner zones. The nucleus is a large structure containing numerous nucleoli. The nuclear envelope is highly invaginated, especially at the side facing the vegetal pole. It is regularly perforated by large nuclear pores. Our results show that the structural organization of Caudiverbera oocytes, although similar to that of other amphibian oocytes, differs from them especially concerning the spatial distribution of several structural components.

  17. Electron Microscope Studies of Nuclear Extrusions in Pancreatic Acinar Cells of the Rat

    PubMed Central

    Clark, Wallace H.

    1960-01-01

    This paper describes "blebs" protruding from the surface of the nucleus into the cytoplasm. The "blebs" are separated from the cytoplasm by 2 membranes which are continuous with the outer and inner nuclear membranes. The "blebs" contain 3 structurally distinct substances. Two of these substances (β and γ substances) are similar to extranucleolar karyoplasm and nucleolar material. The other substance (α substance) is present in every "bleb," but it cannot be readily compared to a recognizable nuclear structure. Cytoplasmic vesicles are described that are apparently different from the Golgi vesicles or the vesicular component of the ergastoplasm. It is suggested that these vesicles may be of nuclear "bleb" origin. A dark karyoplasmic zone extending from the region of the nucleolus into the nuclear "bleb" is shown. This zone may be similar in some respects to the preformed pathway ("Leitbahn") described by Altmann (3) and Hertl (28) and could reflect movement of nuclear material from the nucleolar region into the cytoplasm. The "blebs" are thought to be homologous to structures described by many light microscopists, but they are considerably larger than the nuclear "blebs" described previously by electron microscopists. PMID:13810485

  18. An update of 'basic light and scanning electron microscopic methods for taxonomic studies of ciliated protozoa'.

    PubMed

    Foissner, Wilhelm

    2014-01-01

    This is an update of the review by Foissner (1991). Since then, I have improved some methods considerably. The following methods are described in detail: live observation, supravital staining with methyl green-pyronin, dry silver nitrate impregnation, wet silver nitrate impregnation, silver carbonate impregnation, protargol impregnation (three procedures), scanning electron microscopy, and deciliation. Familiarity with these methods (or modifications) is a prerequisite for successful taxonomic work. No staining method is equally appropriate to all kinds of ciliates. A table is provided which indicates those procedures which work best for certain groups of ciliates. A second table relates to the structures revealed by the procedures. Good descriptions usually demand at least live observation, silver nitrate and protargol or silver carbonate impregnation. Some instructions are provided for distinguishing mono- and dikinetids as well as ciliated and non-ciliated basal bodies in silvered ciliates. Furthermore, I added a section on 'Deposition and Labeling of Preparations'. All methods work not only with ciliates but also with many other heterotrophic and autotrophic flagellated and amoeboid protists. The brilliancy of silver preparations has tempted some taxonomists to neglect live observation. However, many important species characteristics cannot be seen or are changed in silvered specimens. I thus consider all species descriptions based exclusively on silver slides as incomplete and of doubtful value for both α-taxonomists and ecologists.

  19. Electron Microscope Study of Sporulation and Parasporal Crystal Formation in Bacillus thuringiensis

    PubMed Central

    Bechtel, Donald B.; Bulla, Lee A.

    1976-01-01

    A comprehensive ultrastructural analysis of sporulation and parasporal crystal development is described for Bacillus thuringiensis. The insecticidal crystal of B. thuringiensis is initiated at the start of engulfment and is nearly complete by the time the exosporium forms. The crystal and a heretofore unobserved ovoid inclusion develop without any clear association with the forespore septum, exosporium, or mesosomes. These observations contradict previous hypotheses that the crystal is synthesized on the forespore membrane, exosporium, or mesosomes. Formation of forespore septa involves densely staining, double-membrane-bound, vesicular mesosomes that have a bridged appearance. Forespore engulfment is subpolar and also involves mesosomes. Upon completion of engulfment the following cytoplasmic changes occur: decrease in electron density of the incipient forespore membrane; loss of bridged appearance of incipient forespore membrane; change in stainability of incipient forespore, forespore, and mother cell cytoplasms; and alteration in staining quality of plasma membrane. These changes are involved in the conversion of the incipient forespore into a forespore and reflect “commitment” to sporulation. Images PMID:182671

  20. Terminal sprouting in partially denervated muscle of the mouse: a scanning electron microscopic study.

    PubMed

    Torigoe, K

    1988-08-01

    Terminal sprouting in the mouse gastrocnemius muscle was examined by scanning electron microscopy after partial denervation. After one of the two muscle nerves in the medial head was cut, terminal sprouts arose from the outer edge of the intact motor endplates and grew out onto a connective tissue layer on the muscle fibres. The sprouts were very slender along their length, although some had a varicose appearance. The terminal tip of the sprouts was swollen in an amoeba-shaped configuration, forming a growth cone. Several shorter projections surrounded the initial part of a long terminal sprout, whilst in the centre the varicosity had a spindle shape like a diamond: the former most likely indicated the processes of a Schwann cell, and the latter may be a Schwann cell soma. Such swelling patterns suggested that the sprout initially grew out from a growth cone and then the Schwann cells migrated into the growing sprout. The sprouts had no synaptic connections with their muscle fibres at least during the growth cone-forming stage. No structural changes to guide the growing terminal sprouts could be recognized on the flat surface of the muscle fibres. PMID:3193131

  1. Electron-optical microscopic study of incipient dental microdamage from experimental seed and bone crushing

    SciTech Connect

    Peters, C.R.

    1982-03-01

    No living analogue exists for the hypothetical early hominid hard/tough-seed, coarse-root-eating, and bone-crushing masticatory adaptation. To investigate possible microdamage/microwear to dental enamel caused by such usage, puncture-crushing experiments were carried out on single human teeth, using an Instron compression apparatus on the following six test materials: Makapansgat Limeworks chert (e.g., taphonomy), fresh steer longbone, mongongo nuts, Grewia berries, Carob beans, and wild-onion bulbs. Pairs of extracted unworn third molars were utilized, with one tooth acting as the control. The teeth were mounted, ultrasonically cleaned, and two-stage replicas made with a vinyl polysiloxane elastomer and araldite epoxy resin. After Instron loading and materials failure (1.2-395.0 kg) the test items and the crowns were prepared for comparison with scanning electron microscopy and dispersive x-ray elemental analysis and mapping. The results revealed that although grit adhering to food item surfaces caused microscratches (0.1-1.0 micron wide) similar in appearance to those caused by opal phytoliths in grasses, the dicotyledonous seed coats per se were unable to score enamel. This suggests microscratch morphology alone may not provide a reliable indication of food type. In some cases puncture-crushing of bone and hard legumes produced a localized microfracture pattern (crazing with cracks less than or equal to 0.1-1.0 micron wide) that was readily distinguishable from the simulated taphonomic damage caused by chert fragments, suggesting only analysis of enamel mistaphonomic damage caused by chart fragments, suggesting analysis of enamel microfracture patterns may provide clues as to early hominid dietary adaptations.

  2. Nanotip electron gun for the scanning electron microscope.

    PubMed

    Vladár, András E; Radi, Zsolt; Postek, Michael T; Joy, David C

    2006-01-01

    Experimental nanotips have shown significant improvement in the resolution performance of a cold field emission scanning electron microscope (SEM). Nanotip electron sources are very sharp electron emitter tips used as a replacement for the conventional tungsten field emission (FE) electron sources. Nanotips offer higher brightness and smaller electron source size. An electron microscope equipped with a nanotip electron gun can provide images with higher spatial resolution and with better signal-to-noise ratio. This could present a considerable advantage over the current SEM electron gun technology if the tips are sufficiently long-lasting and stable for practical use. In this study, an older field-emission critical dimension (CD) SEM was used as an experimental test platform. Substitution of tungsten nanotips for the regular cathodes required modification of the electron gun circuitry and preparation of nanotips that properly fit the electron gun assembly. In addition, this work contains the results of the modeling and theoretical calculation of the electron gun performance for regular and nanotips, the preparation of the SEM including the design and assembly of a measuring system for essential instrument parameters, design and modification of the electron gun control electronics, development of a procedure for tip exchange, and tests of regular emitter, sharp emitter and nanotips. Nanotip fabrication and characterization procedures were also developed. Using a "sharp" tip as an intermediate to the nanotip clearly demonstrated an improvement in the performance of the test SEM. This and the results of the theoretical assessment gave support for the installation of the nanotips as the next step and pointed to potentially even better performance. Images taken with experimental nanotips showed a minimum two-fold improvement in resolution performance than the specification of the test SEM. The stability of the nanotip electron gun was excellent; the tip stayed useful

  3. ELECTRON MICROSCOPIC STUDIES OF HUMAN GLOMERULONEPHRITIS WITH FERRITIN-CONJUGATED ANTIBODY

    PubMed Central

    Andres, Giuseppe A.; Accinni, Lidia; Hsu, Konrad C.; Zabriskie, John B.; Seegal, Beatrice C.

    1966-01-01

    1. Kidney biopsies from 4 cases of severe acute glomerulonephritis were obtained 11 to 25 days after the onset of clinical manifestations of the disease. These tissues were treated with ferritin-conjugated antibodies to 7S γ-globulin, β1C, and Type 12 streptococcal products. Adjacent pieces of the biopsied material were treated with control ferritin-labeled antisera or with ferritin alone. As further controls, normal renal tissue and renal tissue from patients with other kidney diseases were treated with the same antisera. The 3 antisera to 7S γ-globulin, β1C and Type 12 streptococcus were specifically bound in electron-opaque foreign material in the following renal areas: (a) the lumen of glomerular capillaries; (b) medullary arteriolar walls (2 cases); (c) pinocytic vacuoles and absorption droplets of endothelial or mesangial cells; (d) canals between proliferating mesangial or endothelial cells which connect the capillary lumen with the deep mesangial region or with the endothelial side of the basement membrane; (e) basement membrane proper; (f) subendothelial and certain subepithelial deposits; and (g) Bowman's space. 2. None of the 3 ferritin-conjugated antisera listed above were bound to the nuclei of glomerular cells or to portions of the cytoplasm other than those specified. 3. Ferritin-conjugated antisera to pneumococcus Type II and vaccinia virus and ferritin alone were not bound to any structures in the glomerular tissue. 4. None of the ferritin-conjugated antisera bound to normal renal tissue or to kidney tissue from other renal disease. 5. The data obtained are compatible with the following working hypothesis: Antigen-antibody aggregates of Type 12 streptococcal products, γ-globulin, and complement are present in the circulating blood of patients with severe acute glomerulonephritis. Large amounts of the complexes are caught in the filtering system of the glomeruli. The inflammatory reactions seen in the glomerular structures result from the

  4. Electron microscopical and histochemical studies on the transverse striated muscles of birds after prolonged hypokinesis

    NASA Technical Reports Server (NTRS)

    Belak, M.; Kocisova, J.; Marcanik, J.; Boda, K.; Skarda, R.

    1981-01-01

    Studies of the gastrocnemius muscle were carried out in 4 month old cockerels of the laying hybrid after hypokinesis lasting 15 and 30 days. It was found that restricted movement resulted in dystrophic changes of myotibrils, enlargement of the sarcoplasmic reticulum and oedem of interfibrillar spaces. Histochemical studies revealed focuses of increased activity of non-specific esterase, decreased activity of dehydrogenase of lactic acid and a positive reaction of acid phosphatase.

  5. A light and electron microscopic study of the neuropathy of equine idiopathic laryngeal hemiplegia.

    PubMed

    Duncan, I D; Griffiths, I R; Madrid, R E

    1978-01-01

    A study has been made of the pathological changes in the recurrent laryngeal nerves from horses with clinical and sub-clinical idiopathic laryngeal hemiplegia. Qualitative and quantitative studies showed in clinical cases there was a progressive distal loss of large myelinated fibres in the left recurrent nerve. Regenerating clusters and onion bulbs were frequently seen in affected nerves both at proximal and distal levels. Degenerating axons were characterized by collections of organelles, and denervated bands of Bungner were common. Similar but less severe changes were seen in the left recurrent nerve of sub-clinical cases, and in both the clinical and sub-clinical cases the distal right recurrent nerve was also affected. Teased fibre studies showed evidence of chronic demyelination and remyelination. The aetiology of this chronic neuropathy remains uncertain but the possibility of nerve compression is discussed.

  6. An electron-microscope study of alpha to gamma transformation in an iron-nickel alloy

    NASA Technical Reports Server (NTRS)

    Lobodyuk, V. A.; Khandros, L. G.; Fedas, N. P.

    1980-01-01

    Procedures used to study the alpha to gamma conversion in thin foils of an iron alloy with 32% nickel concentration and initial martensite conversion temperature of -60 C are described. Photomicrographs show deformation twinning as well as changes in samples after they were heated. Reverse conversion is discussed and results are examined.

  7. Mitochondrial variations in the spinal ganglion cells of the slow loris: an electron microscopic study.

    PubMed

    Ahmed, M M; Kanagasuntheram, R

    1976-04-01

    The fine structure os spinal ganglia from seven slow lorises (Nycticebus coucang coucang) was studied following perfusion fixation using different concentrations of glutaraldehyde and post-fixation in 1% osmic acid. Two cell types, one light (63%), and the other dark (37%) were reported out of the total number of 425 neurons counted. Almost all the light cells contained filamentous mitochondria, whereas only 35% of the dark cells contained filamentous mitochondria, the other 65% having vacuolated mitochondria. The significance of this mitochondrial variation in the spinal ganglion cells of the slow loris is undecided.

  8. Electron microscopic study of the differentiation and development of trophocytes and oocytes in Gerris najas (Heteroptera).

    PubMed

    Choi, W C; Nagl, W

    1976-01-01

    The differentiation of oogonia and oocytes, and of trophocytes, from undifferentiated germ line cells has been studied in Gerris najas, a pond skater, from the fourth instar to the adult animal. For the first time criteria have been obtained which allow the distinction between poorly differentiated early oogonia and nurse cells. The most important criteria are the size, shape, and structure of nuclei and mucleoli. This is consistent with the different function of these cell types, which is primarily a different nuclear function: meiosis in the oocytes, and RNA synthesis to support the trophic core and the oocytes in the trophocytes.

  9. Light and electron microscopic studies of the Harderian gland in Bilgorajska goose (Anser anser).

    PubMed

    Klećkowska-Nawrot, Joanna; Chęć, Aleksandra; Goździewska-Harłajczuk, Karolina; Nowaczyk, Renata; Barszcz, Karolina

    2015-09-01

    The Harderian gland (HG) in birds is the dominant orbital gland, which plays an important role in immunological response. Tissue sections taken from adult females of Bilgorajska goose were stained with hematoxylin-eosin, Azan, PAS, AB pH 2.5, AF and HDI. Based on the histological structure the HG in Bilgorajska geese had compound tubular structure with multiple lobules and two types of epithelial cells lining the tubules. Epithelial cells in the central part of the lobes were dark in color and contained serous fluid, while in the deeper layers, epithelial cells were lightly coloured and contained mucous fluid. Histochemical studies showed the presence of neutral mucopolysaccharides and carboxylated acid mucopolysaccharides in the secretory cells. The small number of single plasma cells were present in HDI staining below the basement membrane of the secondary and primary ducts, near the crypts of the main duct. TEM study demonstrated that plasma cells had a large nucleus with condensed heterochromatin and were rich in rough endoplasmic reticulum. The knowledge of gland's structure, and above all an analysis of the immune system components may affect clinical practice and properly conducted immunization of birds.

  10. Malignant hyperthermia susceptibility. A light and electron microscopic study of endomyocardial biopsy specimens from nine patients.

    PubMed

    Mambo, N C; Silver, M D; McLaughlin, P R; Huckell, V F; McEwan, P M; Britt, B A; Morch, J E

    1980-07-01

    Cardiomyopathy develops in some individuals who have a susceptibility to malignant hyperthermia. We studied right ventricular endomyocardial biopsy specimens from nine patients defined as having this disorder because of positive caffeine contracture tests on skeletal muscle biopsy specimens. Three patients had clinical evidence of cardiomyopathy and six did not. Light microscopy showed cytoplasmic contraction bands, perinuclear clearing, and a mild to moderate variation in myocyte and nuclear size. Ultrastructurally cytoplasmic contraction bands were associated with cardiac villi, myofiberlysis, and myofibrillolysis. These changes and occasional breaks in the sarcolemma were regarded as artefacts of the biopsy procedure. Megamitochondriosis with accompanying degenerative changes in the mitochondria were also seen and probably indicate increased cell metabolism; vacuolation of the cytoplasm was regarded as an "aging" phenomenon. Thus, the biopsy specimens were abnormal, but the changes were artefactual or nonspecific and were not unique to this group of patients. Biopsy did not provide a morphological explanation for abnormal cardiac function.

  11. Light and Electron Microscopic Studies on Prenatal Differentiation of Exocrine Pancreas in Buffalo.

    PubMed

    Gupta, Divya; Uppal, Varinder; Bansal, Neelam; Gupta, Anuradha

    2016-01-01

    The study was conducted on pancreas of 24 buffalo fetuses collected from abattoir and Veterinary clinics, GADVASU, Ludhiana. The buffalo fetuses were divided into three groups after measuring their CVRL, namely, group I (CVRL between 0 and 20 cm), group II (CVRL above 20 cm and up to 40 cm), and group III (CVRL above 40 cm) and their approximate age was calculated. The tissues were processed for light and ultrastructural studies. In group I, at 1.2 cm CVRL (34 days), the pancreas comprised tubules and solid nest of undifferentiated epithelial cells. At 7.5 cm CVRL (63 days) acinar cells with zymogen granules were observed. These acinar cells varied in shape from columnar to pyramidal. At 12.8 cm CVRL (86 days), parenchyma began to organize into lobes and lobules. The centroacinar cells were observed at 12.8 cm CVRL (86 days). In group II, at 28.3 cm CVRL (137 days), there was extensive branching of tubules that resulted in highly branched ductal tree connecting exocrine secretary units to the duct system. The interlobular and intralobular ducts were well observed at this age yet the intercalated ducts were not completely developed. In group III, exocrine pancreas showed a massive growth at 48 cm CVRL (182 days) with distinct pancreatic lobes and lobules. At 54 cm CVRL (195 days), well developed pancreatic architecture was seen with the presence of extensive development of exocrine part organized in lobes and lobules with interlobular and intralobular ducts whereas the intercalated ducts were observed in 80 cm CVRL (254 days).

  12. Morphology of irradiated microvasculature: a combined in vivo and electron-microscopic study

    SciTech Connect

    Narayan, K.; Cliff, W.J.

    1982-01-01

    The purpose of this study was to establish a standardized experimental system to investigate the local effects of ionizing irradiation in the absence of systemic responses due to radiation. Twenty fully healed rabbit ear chambers in 13 rabbits were irradiated with single exposures of 7500 rads of beta-rays from a strontium-90 source. The irradiation resulted in an acute response, with cellular infiltration of the ear chambers, loss of vasomotion in arterioles, and vasodilatation. Over the weeks following irradiation, a gradual reduction in the number of blood and lymphatic vessels was noticed. A gradual reduction in the number of cells in the interstitium was also observed. Finally, only a few thin-walled blood vessels remained. Their endothelium contained no recognizable organelles and in places had disappeared completely, to expose the vascular basement membrane to the blood. These vessels were observed to be still flowing. No evidence either of capillary blockage due to swelling of endothelial cells or of platelet aggregation leading to thrombosis was obtained.

  13. An electron microscopical study of chronic ulcers of the colon in rats.

    PubMed Central

    Reeve, D. R.

    1977-01-01

    Chronic colonic ulcers in the rat were produced by the administration of a hydrogen peroxide enema. Lesions of up to 10 months' duration were obtained by this method and a selection was examined ultrastructurally. It was hoped that the study would reveal causes for the chronicity of the lesions. From previous work it appeared that there was no failure of epithelial migration from the edge of the wound. The majority of cells at the ulcer margins demonstrated features of regeneration similar to those seen in other tissues, and that there were no specific changes concomitant with chronic ulceration. The majority of epithelial cells at the ulcer edge showed features of differentiation which indicated that there was no obvious fault in this process so essential to the basic requirements of tissue repair. It is possible that chronicity is produced by a failure of the epithelio-mesenchymal interaction mechanisms which, potentiated by an ischaemia resulting from submucosal vascular damage, results in the consequential death of migrating epithelial cells. This hypothesis is supported by the appearance of a squamous metaplasia in the healing lesions, a process which is commonly attributed to a chronic inflammatory response which may be induced by a relative vascular insufficiency. Images Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16 Fig. 17 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 1 Fig. 2 Fig. 3 Fig. 8 Fig. 9 Fig. 10 PMID:836769

  14. Scanning electron microscopic study of the surface of feline gastric epithelium: a simple method of removing the coating material.

    PubMed

    Al-Tikriti, M; Henry, R W; Al-Bagdadi, F K; Hoskins, J; Titkemeyer, C

    1986-01-01

    Scanning electron microscopic examination of the gastric surface epithelial cells is often hindered by the presence of a coating material. Several methods for removal of coating material on feline gastric mucosa were utilized. The cleansed tissues were evaluated using the scanning electron microscope to assess damage caused by the use of various cleansing methods to surface epithelial cells. The stretched stomach washed several times, including rubbing the mucosal surface with gloved fingers, yielded the best results with no apparent damage to the surface epithelial cells. Flushing unstretched stomachs with saline only did not adequately remove coating material. Flushing unstretched stomachs with saline while stroking the surface with a cotton tipped applicator stick removed debris but damaged the surface epithelium.

  15. Freeze-fracture of infected plant leaves in ethanol for scanning electron microscopic study of fungal pathogens.

    PubMed

    Moore, Jayma A; Payne, Scott A

    2012-01-01

    Fungi often are found within plant tissues where they cannot be visualized with the scanning electron microscope (SEM). We present a simple way to reveal cell interiors while avoiding many common causes of artifact. Freeze-fracture of leaf tissue using liquid nitrogen during the 100% ethanol step of the dehydration process just before critical point drying is useful in exposing intracellular fungi to the SEM. PMID:22183650

  16. Human vaginal epithelium and the epithelial lining of a cyst model constructed from it: a comparative light microscopic and electron microscopic study.

    PubMed

    Thompson, I O; van Wyk, C W; Darling, M R

    2001-11-01

    The light microscopic features and keratin filament distribution of human vaginal epithelium resemble those of buccal mucosa. We used vaginal epithelium to establish a human cyst model in immunodeficient mice. To strengthen the view that this experimental cyst is a suitable model to study mucosal diseases, we compared specific light microscopic and ultra-structural features of vaginal epithelium and the epithelial lining of the cyst. Nineteen cyst walls and 6 specimens of vaginal mucosa, which had been used to establish the cysts, were examined. We counted the number of cell layers of 17 cyst linings and the 6 vaginal specimens. Surface keratinisation was evaluated on sections stained with the Picro-Mallory method. To demonstrate intercellular lamellae and membrane coating granules 2 cyst linings were examined ultra-structurally. The epithelium lining of the cyst wall was thinner than that of vaginal mucosa but the surface keratinisation and ultra-structural features of the intercellular lamellae and membrane coating granules were similar. We concluded that vaginal mucosa is a useful substitute for oral mucosa in the cyst model.

  17. Monocytes become macrophages; they do not become microglia: a light and electron microscopic autoradiographic study using 125-iododeoxyuridine

    SciTech Connect

    Schelper, R.L.; Adrian, E.K. Jr.

    1986-01-01

    This light and electron microscopic autoradiographic study of stab injuries in the spinal cord of mice evaluated the ultrastructural characteristics of cells labeled by incorporation of the thymidine analogue /sup 125/I-5-iodo-2'-deoxyuridine (I-UdR), injected one day prior to injury. I-UdR was used instead of tritiated thymidine (H-TdR) because H-TdR can be reutilized and is therefore not a suitable pulse label for long-term studies of cell migration. Using serial thick and thin sections for autoradiography 614 labeled cells were identified. Labeled cells included 545 monocytes/macrophages, 50 lymphocytes, 17 pericytes, one endothelial cell, and one arachnoid cell. No labeled cell had the morphology of microglia. We concluded that macrophages in stab injuries of the spinal cord of mice are derived from blood monocytes. Blood-derived lymphocytes are also involved in the reaction to spinal cord stab injury. Microglia are not blood-derived and are not seen as a transitional form in the differentiation of monocytes to macrophages.

  18. Small intestinal mucosal injury in the experimental blind loop syndrome. Light- and electron-microscopic and histochemical studies.

    PubMed

    Toskes, P P; Giannella, R A; Jervis, H R; Rout, W R; Takeuchi, A

    1975-05-01

    Microscopic (light and electron) and histochemical abnormalities have been demonstrated in the jejunum of rats with the blind loop syndrome. Three groups of animals were studied: normal control animals, and animals with either self-filling (SF) or self-emptying (SE) blind loops. Vitamin B12 malabsorption and bacterial overgrowth occurred only in those animals with SF blind loops. Three jejunal segments were studied: the blind loop segment and the jejunal segments proximal and distal to the blind loop. In the animals with the blind loop syndrome, those with SF blind loops, the most striking findings occurred in the blind loop itself, with similar but less marked changes in the jejunum distal but not proximal to the blind loop segment. Hypertrophy of both crypts and villi was evident with focal abnormalities of villus architecture. Approximately 10 to 20% of the columnar cells in the upper half of the villi were swollen and vesiculated. By electron microscopy microvilli demonstrated a variety of degeneration changes and the glycocalyx and terminal web were disrupted. Mitochondria and endoplasmic reticulum (ER), both smooth and rough, were swollen. Concentric whorls of parallel membranes and long, curvilinear rough ER were present in the cytoplasm. Histochemically, there was loss of enzymatic activity in the epithelial brush border, mitochondria and ER. Inasmuch as bacterial invasion of the jejunal mucosa was not seen, the etiology of these changes is not known but may involve bacterial "toxins" or products of bacterial metabolism. These morphological observations demonstrate that both brush border and intracellular injury occur in the jejunal epithelial cell of rats with the experimental blind loop syndrome.

  19. Isotope analysis in the transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Susi, Toma; Hofer, Christoph; Argentero, Giacomo; Leuthner, Gregor T.; Pennycook, Timothy J.; Mangler, Clemens; Meyer, Jannik C.; Kotakoski, Jani

    2016-10-01

    The Ångström-sized probe of the scanning transmission electron microscope can visualize and collect spectra from single atoms. This can unambiguously resolve the chemical structure of materials, but not their isotopic composition. Here we differentiate between two isotopes of the same element by quantifying how likely the energetic imaging electrons are to eject atoms. First, we measure the displacement probability in graphene grown from either 12C or 13C and describe the process using a quantum mechanical model of lattice vibrations coupled with density functional theory simulations. We then test our spatial resolution in a mixed sample by ejecting individual atoms from nanoscale areas spanning an interface region that is far from atomically sharp, mapping the isotope concentration with a precision better than 20%. Although we use a scanning instrument, our method may be applicable to any atomic resolution transmission electron microscope and to other low-dimensional materials.

  20. The value of external morphology in the identification of larval anisakid nematodes: a scanning electron microscope study.

    PubMed

    Weerasooriya, M V; Fujino, T; Ishii, Y; Kagei, N

    1986-01-01

    We studied larval nematodes of four genera of the Anisakidae using a scanning electron microscope (SEM). The anterior and posterior extremities and cuticular structures of the 3rd-stage larvae (L3) of Anisakis type I, Pseudoterranova decipiens, Contracaecum type B and Hysterothylacium were examined. The 4th-stage larvae (L4) of Anisakis type I, P. decipiens, recovered after infection into laboratory rats, and the L3 and L4 of Anisakis type I larvae from human were also examined in the same way. There were generic differences in the shape and size of the lip bulges, external papillary structures, the appearance of the boring tooth, the width and depth of the grooves and ridges of the cuticle and the caudal structures of the L3. In Anisakis type I and P. decipiens L3, changes were seen in the anterior extremity, cuticle and posterior extremity after molting to the L4. Similar changes can be expected in larvae infecting man. The L4 of Anisakis type I from rat and man were similar, while the L4 of Anisakis type I and P. decipiens showed differences. These ultrastructural differences might be of value in the identification of fragments recovered during endoscopy in man. PMID:3799008

  1. Effect of fluoride and cobalt on forming enamel: scanning electron microscope and X-ray microanalysis study

    SciTech Connect

    Ashrafi, S.H.; Eisenmann, D.R.; Zaki, A.E.; Liss, R.

    1988-09-01

    The forming surfaces of enamel of rat incisors were examined by scanning electron microscope one hour after injection of either 5 mg/100 g body weight of sodium fluoride or 12 mg/100 g body weight of cobalt chloride. The cell debris from the surfaces of the separated incisors was either gently wiped off with soft facial tissues or chemically removed by treating with NaOH, NaOCl or trypsin. Best results to remove cell debris were obtained from 0.25% trypsin treatment. SEM studies revealed that the surface of the normal secretory enamel was characteristic in appearance with well-developed smooth prism outlines. In fluoride specimens the prism outlines were feathery in appearance, laced with protruding spine-shaped clusters of mineral crystals. In the case of cobalt treatment, prism outlines were less uniform and in some areas they were incomplete. The calcium concentration of surface enamel was significantly lower in the cobalt-treated specimens than those from control and fluoride-treated animals. The Ca:Mg ratio was also lower in cobalt-treated specimens as compared to control and fluoride-treated ones.

  2. Ponderomotive phase plate for transmission electron microscopes

    DOEpatents

    Reed, Bryan W.

    2012-07-10

    A ponderomotive phase plate system and method for controllably producing highly tunable phase contrast transfer functions in a transmission electron microscope (TEM) for high resolution and biological phase contrast imaging. The system and method includes a laser source and a beam transport system to produce a focused laser crossover as a phase plate, so that a ponderomotive potential of the focused laser crossover produces a scattering-angle-dependent phase shift in the electrons of the post-sample electron beam corresponding to a desired phase contrast transfer function.

  3. Electron microscopic evaluation and fission product identification of irradiated TRISO coated particles from the AGR-1 experiment: A preliminary Study

    SciTech Connect

    I J van Rooyen; D E Janney; B D Miller; J L Riesterer; P A Demkowicz

    2012-10-01

    ABSTRACT Post-irradiation examination of coated particle fuel from the AGR-1 experiment is in progress at Idaho National Laboratory and Oak Ridge National Laboratory. In this presentation a brief summary of results from characterization of microstructures in the coating layers of selected irradiated fuel particles with burnup of 11.3% and 19.3% FIMA will be given. The main objective of the characterization were to study irradiation effects, fuel kernel porosity, layer debonding, layer degradation or corrosion, fission-product precipitation, grain sizes, and transport of fission products from the kernels across the TRISO layers. Characterization techniques such as scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, and wavelength dispersive spectroscopy were used. A new approach to microscopic quantification of fission-product precipitates is also briefly demonstrated. The characterization emphasized fission-product precipitates in the SiC-IPyC interface, SiC layer and the fuel-buffer interlayer, and provided significant new insights into mechanisms of fission-product transport. Although Pd-rich precipitates were identified at the SiC-IPyC interlayer, no significant SiC-layer thinning was observed for the particles investigated. Characterization of these precipitates highlighted the difficulty of measuring low concentration Ag in precipitates with significantly higher concentrations of contain Pd and U. Different approaches to resolving this problem are discussed. Possible microstructural differences between particles with high and low releases of Ag particles are also briefly discussed, and an initial hypothesis is provided to explain fission-product precipitate compositions and locations. No SiC phase transformations or debonding of the SiC-IPyC interlayer as a result of irradiation were observed. Lessons learned from the post-irradiation examination are described and future actions are recommended.

  4. ELECTRON MICROSCOPE STUDY OF THE RELATIONSHIP BETWEEN MESOSOME LOSS AND THE STABLE L STATE (OR PROTOPLAST STATE) IN BACILLUS SUBTILIS

    PubMed Central

    Ryter, Antoinette; Landman, Otto E.

    1964-01-01

    Ryter, Antoinette (Institut Pasteur, Paris, France), and Otto E. Landman. An electron microscope study of the relationship between mesosome loss and the stable L-state (or protoplast state) in Bacillus subtilis. J. Bacteriol. 88:457–467. 1964.—In a prior publication, it was postulated that inability of protoplasts to restart cell-wall synthesis and cell division and the inability of stable mass-conversion L forms to return to the bacillary state were both equivalent and both due to the interruption of a membrane-associated reaction sequence. It was further postulated that this reaction sequence might reside in the mesosome. In the present publication, it is shown by means of electron microscopy of thin sections that protoplasts and L forms do not contain mesosomes. The sequence of events leading to loss of the mesosomes during protoplasting is as follows. Soon after lysozyme addition, the mesosomes are extruded from the cell interior into the space between cell wall and cytoplasmic membrane. Mesosome fragments in the form of small vesicles gather at the poles of the cells and are released, along with intact protoplasts, when the wall fragments. (Sudden shift of bacilli to hypertonic environment also causes extrusion and fragmentation of mesosomes, but this damage is later repaired.) In intact bacilli, mesosomes are in contact with both the peripheral membrane and nuclear material. Upon extrusion of the mesosomes, a direct attachment between nuclear material and cytoplasmic membrane is observed. Deoxyribonucleic acid (DNA)-membrane attachment may play a role in the control of DNA replication. Bacillus subtilis L-colonies consist of irregularly shaped bodies of varying sizes, bounded only by a membrane. Many of the smaller bodies do not contain nuclear material, and many of the large ones appear inviable. Division is accomplished by a disorganized-appearing constriction process. There are no septa. Images PMID:14203364

  5. Science 101: How Does an Electron Microscope Work?

    ERIC Educational Resources Information Center

    Robertson, Bill

    2013-01-01

    Contrary to popular opinion, electron microscopes are not used to look at electrons. They are used to look for structure in things that are too small to observe with an optical microscope, or to obtain images that are magnified much more than is obtainable with an optical microscope. To understand how electron microscopes work, it will help to go…

  6. Transmission and scanning electron microscope study on the secondary cyclic hardening behavior of interstitial-free steel

    SciTech Connect

    Shih, Chia-Chang; Ho, New-Jin; Huang, Hsing-Lu

    2009-11-15

    Strain controlled fatigue experiment was employed to evaluate automotive grade interstitial-free ferrite steel. Hundreds of grains were examined by scanning electron microscope under electron channeling contrast image technique of backscattered electron image mode for comprehensive comparison of micrographs with those taken under transmission electron microscope. The cyclic stress responses clearly revealed that rapid hardening occurs at the early stage of cycling as a result of multiplication of dislocations to develop loop patches, dipolar walls and dislocation cells at various total strain amplitudes. After primary rapid hardening, stress responses varied from being saturated to further hardening according to dislocation structure evolution at various strain amplitudes. The fatigue failure was always accompanied with further hardening including secondary hardening. The corresponding dislocation structures with the three types of hardening behaviors are discussed. Once the secondary hardening starts, dislocation cells began to develop along grain boundaries in the low strain region and then extended into grain interiors as strain amplitudes increased and cycling went on. The secondary hardening rates were found to be directly proportional to their strain amplitudes.

  7. Scanning electron microscopic autoradiography of lung

    SciTech Connect

    Lauhala, K.E.; Sanders, C.L.; McDonald, K.E.

    1988-09-01

    Scanning electron microscopic (SEM) autoradiography of the lung is being used to determine the distribution of inhaled, alpha particle-emitting, plutonium dioxide particles. SEM autoradiography provides high visual impact views of alpha activity. Particles irradiating the bronchiolar epithelium were detected both on the bronchiolar surface and in peribronchiolar alveoli. The technique is being used to obtain quantitative data on the clearance rates of plutonium particles from bronchi and bronchioles.

  8. Examples of electrostatic electron optics: the Farrand and Elektros microscopes and electron mirrors.

    PubMed

    Hawkes, P W

    2012-08-01

    The role of Gertrude Rempfer in the design of the Farrand and Elektros microscopes is evoked. The study of electron mirror optics, aberration correction using mirrors and the development of microscopes employing electron mirrors are recapitulated, accompanied by a full bibliography, of earlier publications in particular.

  9. Effect of water stress on cotton leaves : I. An electron microscopic stereological study of the palisade cells.

    PubMed

    Berlin, J; Quisenberry, J E; Bailey, F; Woodworth, M; McMichael, B L

    1982-07-01

    Palisade cells from fully expanded leaves from irrigated and nonirrigated, field grown cotton (Gossypium hirsutum L. cv. Paymaster 266) were subjected to a microscopic examination to evaluate the effect of water stress on subcellular structures. The water potential difference between the two treatments was 13 bars at the time of sampling. The dimensions of the palisade cells and their density per unit leaf area were determined by light microscopy. Palisade cells from stressed plants had the same diameter, but were taller than their counterparts in irrigated plants. The density of the palisade cells was the same in both treatments as was the fractional volume of the intercellular space. It was concluded that the reduced leaf area observed in the stressed plants resulted primarily from a mitotic sensitivity to water stress. Further, expansion of palisade cells was not inhibited by the stress imposed in this study.Morphometric analysis of electron micrographs was used to evaluate the subcellular structure of palisade cells from nonstressed and stressed plants. The fractional volumes of cell walls, total cytoplasm, chloroplasts, starch granules, intrachloroplast bodies, mitochondria, peroxisomes, and central vacuoles were determined. The surface densities of grana and stroma lamellae, outer chloroplast membranes, mitochondrial cristae, endoplasmic reticulum and Golgi cisternae were also measured. The number of chloroplasts, mitochondria, and peroxisomes were determined. These data were expressed as actual volumes, areas, and numbers per palisade cell for each treatment. Palisade cells from stressed plants had thinner cell walls, larger central vacuoles and approximately the same amount of cytoplasm compared to cells from nonstressed plants. Within the cytoplasm, stressed plants had more but smaller chloroplasts with increased grana and stroma lamellae surfaces, larger mithchondria with reduced cristae surfaces, smaller peroxisomes and reduced membrane surfaces of

  10. Bonding of contemporary glass ionomer cements to different tooth substrates; microshear bond strength and scanning electron microscope study

    PubMed Central

    El Wakeel, Aliaa Mohamed; Elkassas, Dina Wafik; Yousry, Mai Mahmoud

    2015-01-01

    Objective: This study was conducted to evaluate the microshear bond strength (μSBS) and ultramorphological characterization of glass ionomer (GI) cements; conventional GI cement (Fuji IX, CGI), resin modified GI (Fuji II LC, RMGI) and nano-ionomer (Ketac N100, NI) to enamel, dentin and cementum substrates. Materials and Methods: Forty-five lower molars were sectioned above the cemento-enamel junction. The occlusal surfaces were ground flat to obtain enamel and dentin substrates, meanwhile the cervical one-third of the root portion were utilized to evaluate the bonding efficacy to cementum substrate. Each substrate received microcylinders from the three tested materials; which were applied according to manufacturer instructions. μSBS was assessed using a universal testing machine. The data were analyzed using two-way analysis of variance (ANOVA) and Tukey's post-hoc test. Modes of failure were examined using stereomicroscope at ×25 magnification. Interfacial analysis of the bonded specimens was carried out using environmental field emission scanning electron microscope. Results: Two-way ANOVA revealed that materials, substrates and their interaction had a statistically significant effect on the mean μSBS values at P values; ˂0.0001, 0.0108 and 0.0037 respectively. RMGI showed statistically significant the highest μSBS values to all examined tooth substrates. CGI and RMGI show substrate independent bonding efficiency, meanwhile; NI showed higher μSBS values to dentin and cementum compared to enamel. Conclusion: Despite technological development of GI materials, mainly the nano-particles use, better results have not been achieved for both investigations, when compared to RMGI, independent of tooth substrate. PMID:26038646

  11. Influence of mechanical noise inside a scanning electron microscope

    SciTech Connect

    Gaudenzi de Faria, Marcelo; Haddab, Yassine Le Gorrec, Yann; Lutz, Philippe

    2015-04-15

    The scanning electron microscope is becoming a popular tool to perform tasks that require positioning, manipulation, characterization, and assembly of micro-components. However, some of these applications require a higher level of performance with respect to dynamics and precision of positioning. One limiting factor is the presence of unidentified noises and disturbances. This work aims to study the influence of mechanical disturbances generated by the environment and by the microscope, identifying how these can affect elements in the vacuum chamber. To achieve this objective, a dedicated setup, including a high-resolution vibrometer, was built inside the microscope. This work led to the identification and quantification of main disturbances and noise sources acting on a scanning electron microscope. Furthermore, the effects of external acoustic excitations were analysed. Potential applications of these results include noise compensation and real-time control for high accuracy tasks.

  12. Characterization of two types of crystalloids in pleomorphic adenomas of minor salivary glands. A light-microscopic, electron-microscopic, and histochemical study.

    PubMed

    Campbell, W G; Priest, R E; Weathers, D R

    1985-02-01

    Crystalloids have been previously described in salivary gland tumors. In order to ascertain the incidence of these structures, the authors reviewed a series of 294 minor salivary gland tumors. One hundred thirty pleomorphic adenomas were identified, and 6 of these contained crystalloids. No crystalloids were found in other benign or malignant salivary gland tumors. These six file cases and a recent seventh case containing crystalloids were studied by light and electron microscopy and with histochemistry. Two types of crystalloids were found. One case contained previously described tyrosine-rich crystalloids, and the other six contained crystalloids composed of radially arranged collagen fibers. Both types of crystalloids are further characterized and discussed.

  13. Environmental scanning electron microscope (ESEM). Final report

    SciTech Connect

    Marder, A.; Barmak, K.; Williams, D.

    1998-11-01

    The Environmental Scanning Electron Microscope (ESEM) was acquired by a grant from the Department of Energy University Research Instrumentation Program and matching funds from Lehigh University and industry. The equipment is installed as part of the electron microscopy laboratories and is being utilized on a regular basis. Over 20 graduate and undergraduate students from the Department of Materials Science and Engineering as well as other department in the University have included this instrument in their research. In addition, the ESEM has been used in several courses including MAT 427 -- Advanced Scanning Electron Microscopy, a graduate course offered every other year. Examples are given of how the ESEM has been included in the research programs.

  14. In situ electron microscope study of the phase transformation, structure and growth of thin Te1-xSex films

    NASA Astrophysics Data System (ADS)

    Vermaak, J. S.; Raubenheimer, D.

    1988-01-01

    An in-situ electron microscope technique was utilized to observe directly the amorphous-to-crystalline phase transformation, the isothermal growth rates, as well as the orientation and structure of the recrystallized films for the Te1-xSex alloy system for x=0.2, 0.3 and 0.4. Activation energies of E=0.91, 0.93 and 0.96 eV and crystallization temperatures of Tc=-14, 81.5 and 85°C for the three alloys, respectively, were found. In all three cases the crystallization process originated from single crystalline nuclei with a hexagonal structure and with the c-axis in general parallel to the substrate surface.

  15. Microscopic properties of degradation-free capped GdN thin films studied by electron spin resonance

    SciTech Connect

    Shimokawa, Tokuro; Fukuoka, Yohei; Fujisawa, Masashi; Zhang, Weimin; Okubo, Susumu; Ohta, Hitoshi; Sakurai, Takahiro; Vidyasagar, Reddithota; Yoshitomi, Hiroaki; Kitayama, Shinya; Kita, Takashi

    2015-01-28

    The microscopic magnetic properties of high-quality GdN thin films have been investigated by electron spin resonance (ESR) and ferromagnetic resonance (FMR) measurements. Detailed temperature dependence ESR measurements have shown the existence of two ferromagnetic components at lower temperatures, which was not clear from the previous magnetization measurements. The temperature, where the resonance shift occurs for the major ferromagnetic component, seems to be consistent with the Curie temperature obtained from the previous magnetization measurement. On the other hand, the divergence of line width is observed around 57 K for the minor ferromagnetic component. The magnetic anisotropies of GdN thin films have been obtained by the analysis of FMR angular dependence observed at 4.2 K. Combining the X-ray diffraction results, the correlation between the magnetic anisotropies and the lattice constants is discussed.

  16. Transformation of diamond nanoparticles into onion-like carbon by electron irradiation studied directly inside an ultrahigh-vacuum transmission electron microscope

    SciTech Connect

    Hiraki, J.; Mori, H.; Taguchi, E.; Yasuda, H.; Kinoshita, H.; Ohmae, N.

    2005-05-30

    In situ observation of the transformation of diamond nanoparticles (DNP) into onion-like carbon (OLC) was made during electron-beam irradiation inside an ultrahigh-vacuum transmission electron microscope at 300 kV with 8.5x10{sup 23} e/m{sup 2}. 5 nm DNP changed into OLC within about 10 min of irradiation, while 20 nm DNP did not change to OLC but to graphite. Therefore, the size effect is critical to the formation of OLC. The mechanism of formation of OLC from DNP is discussed.

  17. Effect of various chemical agents used in gingival retraction systems on smear layer: Scanning electron microscope study

    PubMed Central

    Lahoti, Krishna Shivraj

    2016-01-01

    Background: Chemical agents used for gingival retraction affects the smear layer. Aim: To determine the effect of three different chemical agents used for gingival retraction systems on smear layer. Materials and Methods: Four human premolars were prepared using air-rotor with air-water spray to receive full crown restoration. Three of them were treated with 21.3% aluminum chloride for 10 min, 0.05% oxymetazoline hydrochloride for 10 min, and expasyl for 2 min, respectively. One sample was left untreated. Then, the tooth specimens were rinsed with tap water to remove any residue of test materials. All the samples (treated and untreated) were processed by scanning electron microscope (SEM). Processed samples were examined under SEM at ×2400 to evaluate the effect of chemical agents on smear layer. Results: SEM examination revealed that 0.05% oxymetazoline hydrochloride for 10 min produced no alteration to smear layer followed by minimum alteration by expasyl for 2 min and complete removal of smear layer with etching of dentin with 21.3% aluminum chloride for 10 min. Conclusion: 0.05% oxymetazoline hydrochloride and expasyl are kind to smear layer. PMID:27041896

  18. A light and electron microscopic evaluation of Zyderm collagen and Zyplast implants in aging human facial skin. A pilot study.

    PubMed

    Stegman, S J; Chu, S; Bensch, K; Armstrong, R

    1987-12-01

    Four patients received Zyderm collagen implant (ZCI) or Zyplast implant (ZI) in preauricular and infraauricular regions of facial skin periodically between one and nine months. Both materials were identified microscopically in the mid- to deep dermis at all points of the study and, in 60% to 70% of the injected sites, some material was also present subdermally. A slow, gradual colonization of ZCI by fibroblasts was noted compared with a delayed intense interaction of these cells with ZI. Also, there was some new collagen deposition associated with remodeling of the ZI, while no demonstrable synthetic activity occurred in relationship to ZCI. The results suggest that ZCI and ZI "migrate" deeper and eventually move into the subcutaneous plane. This movement could explain the loss of correction at six to nine months that is noted when this implant is used for age-related changes.

  19. [A view of tropical biology through the electron microscope].

    PubMed

    Hernández-Chavarría, Francisco

    2002-01-01

    The first electron microscope in Costa Rica was a donation from the government of Japan through its International Cooperation Agency (JICA) in 1974. This donation made possible the consolidation of what was to become the University of Costa Rica's Electron Microscope Unit (UME). Within three years the first scientific papers were published, dealing with ultrastructural aspects of "Corn's rayado fino virus" and rotavirus, viral agent of human diarrhea. Subsequent papers out of the UME were published for the most part in the Journal of Tropical Biology, totaling at least 50 in that journal alone by the year 2000. With the recent acquisition of Energy Dispersive Spectrometer to coupled in transmission electron microscope and scanning electron microscope to X ray analysis, the data acquisition of the UME has been greatly enhanced, making possible to analyze both structure and elemental chemical composition in a specimen. Other applications of this new technology include studies of environmental pollution with heavy metals, such as comparative analysis of residues on leaves from urban areas and those on leaves from primary forest. PMID:12947579

  20. Assembly of ovarian follicles in the caecilians Ichthyophis tricolor and Gegeneophis ramaswamii: light and transmission electron microscopic study.

    PubMed

    Beyo, R S; Sreejith, P; Divya, L; Oommen, O V; Akbarsha, M A

    2007-08-01

    Though much is known about various aspects of reproductive biology of amphibia, there is little information on the cellular and mechanistic basis of assembly of ovarian follicles in this group. This is especially true of the caecilians. Therefore, taking advantage of the abundant distribution of caecilians in the Western Ghats of India, two species of caecilians, Ichthyophis tricolor and Gegeneophis ramaswamii, were subjected to light and transmission electron microscopic analysis to trace the sequential changes during the assembly of ovarian follicles. The paired ovaries of these caecilians are elongated sac-like structures each including numerous vitellogenic follicles. The follicles are connected by a connective tissue stroma. This stroma contains nests of oogonia, primary oocytes and pregranulosa cells as spatially separated nests. During assembly of follicles the oocytes increase in size and enter the meiotic prophase when the number of nucleoli in the nucleus increases. The mitochondrial cloud or Balbiani vitelline body, initially localized at one pole of the nucleus, disperses through out the cytoplasm subsequently. Synaptonemal complexes are prominent in the pachytene stage oocytes. The pregranulosa cells migrate through the connective tissue fibrils of the stroma and arrive at the vicinity of the meiotic prophase oocytes. On contacting the oocyte, the pregranulosa cells become cuboidal in shape, wrap the diplotene stage oocyte as a discontinuous layer and increase the content of cytoplasmic organelles and inclusions. The oocytes increase in size and are arrested in diplotene when the granulosa cells become flat and form a continuous layer. Soon a perivitelline space appears between the oolemma and granulosa cells, completing the process of assembly of follicles. Thus, the events in the establishment of follicles in the caecilian ovary are described.

  1. Assembly of ovarian follicles in the caecilians Ichthyophis tricolor and Gegeneophis ramaswamii: light and transmission electron microscopic study.

    PubMed

    Beyo, R S; Sreejith, P; Divya, L; Oommen, O V; Akbarsha, M A

    2007-08-01

    Though much is known about various aspects of reproductive biology of amphibia, there is little information on the cellular and mechanistic basis of assembly of ovarian follicles in this group. This is especially true of the caecilians. Therefore, taking advantage of the abundant distribution of caecilians in the Western Ghats of India, two species of caecilians, Ichthyophis tricolor and Gegeneophis ramaswamii, were subjected to light and transmission electron microscopic analysis to trace the sequential changes during the assembly of ovarian follicles. The paired ovaries of these caecilians are elongated sac-like structures each including numerous vitellogenic follicles. The follicles are connected by a connective tissue stroma. This stroma contains nests of oogonia, primary oocytes and pregranulosa cells as spatially separated nests. During assembly of follicles the oocytes increase in size and enter the meiotic prophase when the number of nucleoli in the nucleus increases. The mitochondrial cloud or Balbiani vitelline body, initially localized at one pole of the nucleus, disperses through out the cytoplasm subsequently. Synaptonemal complexes are prominent in the pachytene stage oocytes. The pregranulosa cells migrate through the connective tissue fibrils of the stroma and arrive at the vicinity of the meiotic prophase oocytes. On contacting the oocyte, the pregranulosa cells become cuboidal in shape, wrap the diplotene stage oocyte as a discontinuous layer and increase the content of cytoplasmic organelles and inclusions. The oocytes increase in size and are arrested in diplotene when the granulosa cells become flat and form a continuous layer. Soon a perivitelline space appears between the oolemma and granulosa cells, completing the process of assembly of follicles. Thus, the events in the establishment of follicles in the caecilian ovary are described. PMID:17637101

  2. Satellite Characterization of Biomass Burning: Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope Study of Combustion Experiments

    NASA Astrophysics Data System (ADS)

    Padilla, D.; Steiner, J. C.

    2005-12-01

    Fourier Transform Infrared (FTIR) examination of the combustion products of selected forest materials using a meeker burner flame at temperatures up to 500 degrees Celsius produces a cluster of broad distinct peaks throughout the 400 to 4000 cm-1 wavenumber interval. Distinct bands bracketed by wavenumbers 400-700, 1500-1700, 2200-2400 and 3300-3600 cm-1 show variable intensity with an average difference between the least absorbing and most strongly absorbing species of approximately fifty percent. Given that spectral band differences of ten percent are within the range of modern satellite spectrometers, these band differences are of potential value for discriminating between fires that are impacting a range of vegetation types. Corresponding scanning electron microscope and energy dispersive micro-chemical (SEM/ED) analysis establishes that the evolved soot particles exhibit a characteristic rounded morphology, are carbon rich and host a wide range of adsorbed elements, including calcium, aluminum, potassium, silicon, sulfur and trace nitrogen. Combustion experiments involving leaves and branches as a subset of the biomass experiments at 200-500 degrees Celsius yield a similar broad background, but with peak shifts for maxima residing at less than 1700 cm-1. Additional peaks appear in the ranges 1438-1444, 875 and 713 cm-1. These peak are of potential use for discriminating between hot and smoldering fires, and between soot and smoke yields from green woods and whole-wood or lumber. The spectral shifts noted for low temperature smoldering conditions are in the vicinity of those cited for green vegetation and may not be resolved by present satellite platforms. Nevertheless, the experimental peak data set is of potential use for discriminating between a conflagration or accentuated fire and one characterized by smoldering at low temperature. SEM/ED analysis of the combusted leaf, branch, bark and various crown assemblages yields comparable morphological and

  3. A scanning electron microscopic study of microvascular anastomoses on irradiated vessels: short-term effect of irradiation

    SciTech Connect

    De Wilde, R.; Boeckx, W.; Van Der Schueren, E.; Guelinckx, P.; Gruwez, J.

    1983-01-01

    Experiments were carried out to determine the effect of previous irradiation on microvascular arterial anastomoses. The study focused on regeneration of endothelial cells and thrombus formation. Careful examination with scanning electron microscopy (SEM) showed a difference between irradiated animals and a control group. In the irradiated group one can notice a decreased regeneration, a greater amount of fibrin and platelets, and a higher incidence of microthrombi.

  4. Comparative analysis of endodontic smear layer removal efficacy of 17% ethylenediaminetetraacetic acid, 7% maleic acid, and 2% chlorhexidine using scanning electron microscope: An in vitro study

    PubMed Central

    Attur, Kailash; Joy, Mathew T.; Karim, Riyas; Anil Kumar, V. J.; Deepika, C.; Ahmed, Haseena

    2016-01-01

    Aim: The aim of the present study was to evaluate the efficiency of different endodontic irrigants in the removal of smear layer through scanning electron microscopic image analysis. Materials and Methods: The present in vitro study was carried out on 45 single-rooted extracted human mandibular premolar teeth with single canal and complete root formation. Teeth were randomly assigned to three groups with 15 teeth in each group. Group I samples were irrigated with 17% ethylenediaminetetraacetic (EDTA) irrigation, Group II with 7% maleic acid irrigation, and Group III with 2% chlorhexidine irrigation. Scanning electron microscope evaluation was done for the assessment of smear layer removal in the coronal, middle, and apical thirds. Comparison of the smear layer removal between the three different groups was done by Kruskal–Wallis test, followed by Mann–Whitney U test for comparing individual groups. A P value less than 0.05 was considered to be statistically significant. Results: Statistically significant difference was seen between the two test groups (17% EDTA vs. 7% maleic acid and 17% EDTA vs. 2% chlorhexidine) in smear layer removal at coronal, middle, and apical thirds of the root canal. The most efficient smear layer removal was seen in Group I with 17% EDTA irrigation compared with other groups (P < 0.05) and the least by 2% chlorhexidine. Conclusion: The present study shows that 17% EDTA efficiently removes the smear layer from root canal walls.

  5. Comparative analysis of endodontic smear layer removal efficacy of 17% ethylenediaminetetraacetic acid, 7% maleic acid, and 2% chlorhexidine using scanning electron microscope: An in vitro study

    PubMed Central

    Attur, Kailash; Joy, Mathew T.; Karim, Riyas; Anil Kumar, V. J.; Deepika, C.; Ahmed, Haseena

    2016-01-01

    Aim: The aim of the present study was to evaluate the efficiency of different endodontic irrigants in the removal of smear layer through scanning electron microscopic image analysis. Materials and Methods: The present in vitro study was carried out on 45 single-rooted extracted human mandibular premolar teeth with single canal and complete root formation. Teeth were randomly assigned to three groups with 15 teeth in each group. Group I samples were irrigated with 17% ethylenediaminetetraacetic (EDTA) irrigation, Group II with 7% maleic acid irrigation, and Group III with 2% chlorhexidine irrigation. Scanning electron microscope evaluation was done for the assessment of smear layer removal in the coronal, middle, and apical thirds. Comparison of the smear layer removal between the three different groups was done by Kruskal–Wallis test, followed by Mann–Whitney U test for comparing individual groups. A P value less than 0.05 was considered to be statistically significant. Results: Statistically significant difference was seen between the two test groups (17% EDTA vs. 7% maleic acid and 17% EDTA vs. 2% chlorhexidine) in smear layer removal at coronal, middle, and apical thirds of the root canal. The most efficient smear layer removal was seen in Group I with 17% EDTA irrigation compared with other groups (P < 0.05) and the least by 2% chlorhexidine. Conclusion: The present study shows that 17% EDTA efficiently removes the smear layer from root canal walls. PMID:27652250

  6. A sub-cm micromachined electron microscope

    NASA Technical Reports Server (NTRS)

    Feinerman, A. D.; Crewe, D. A.; Perng, D. C.; Shoaf, S. E.; Crewe, A. V.

    1993-01-01

    A new approach for fabricating macroscopic (approximately 10x10x10 mm(exp 3)) structures with micron accuracy has been developed. This approach combines the precision of semiconductor processing and fiber optic technologies. A (100) silicon wafer is anisotropically etched to create four orthogonal v-grooves and an aperture on each 10x12 mm die. Precision 308 micron optical fibers are sandwiched between the die to align the v-grooves. The fiber is then anodically bonded to the die above and below it. This procedure is repeated to create thick structures and a stack of 5 or 6 die will be used to create a miniature scanning electron microscope (MSEM). Two die in the structure will have a segmented electrode to deflect the beam and correct for astigmatism. The entire structure is UHV compatible. The performance of an SEM improves as its length is reduced and a sub-cm 2 keV MSEM with a field emission source should have approximately 1 nm resolution. A low voltage high resolution MSEM would be useful for the examination of biological specimens and semiconductors with a minimum of damage. The first MSEM will be tested with existing 6 micron thermionic sources. In the future a micromachined field emission source will be used. The stacking technology presented in this paper can produce an array of MSEMs 1 to 30 mm in length with a 1 mm or larger period. A key question being addressed by this research is the optimum size for a low voltage MSEM which will be determined by the required spatial resolution, field of view, and working distance.

  7. Interaction of electrons with light metal hydrides in the transmission electron microscope.

    PubMed

    Wang, Yongming; Wakasugi, Takenobu; Isobe, Shigehito; Hashimoto, Naoyuki; Ohnuki, Somei

    2014-12-01

    Transmission electron microscope (TEM) observation of light metal hydrides is complicated by the instability of these materials under electron irradiation. In this study, the electron kinetic energy dependences of the interactions of incident electrons with lithium, sodium and magnesium hydrides, as well as the constituting element effect on the interactions, were theoretically discussed, and electron irradiation damage to these hydrides was examined using in situ TEM. The results indicate that high incident electron kinetic energy helps alleviate the irradiation damage resulting from inelastic or elastic scattering of the incident electrons in the TEM. Therefore, observations and characterizations of these materials would benefit from increased, instead decreased, TEM operating voltage.

  8. Miniature electron microscope beam column optics

    NASA Astrophysics Data System (ADS)

    Loyd, Jody Stuart

    This investigation is in the area of electrostatic lens design with the overarching goal of contributing to the creation of a miniaturized scanning electron microscope (SEM) for use in mineralogical analysis or detection of signs of life on the surface of Mars. Such an instrument could also have application in the exploration of Earth's moon, planetary moons, asteroids, or comets. Other embodiments could include tabletop or field portable SEMs for use on Earth. The scope of this research is in the design of a beam column that attains focusing, demagnification, and aberration control within the smallest achievable package. The goals of planetary exploration and of spaceflight in general impose severe constraints on the instrument's mass and electrical power consumption, while favoring a robust design of small size and high rigidity that is also simple to align. To meet these requirements a design using electrostatic lenses was favored because of the lower power requirement and mass of electrostatic versus magnetic lenses, their relatively simple construction, as well as inherently easier shielding from extraneous fields. In modeling the lens field, a hybrid of a Boundary Element Method (BEM) and a Fourier series solution was employed, whereby an initial solution from the BEM is used to derive the bounding potential of a cylindrical subdomain for the subsequent Fourier series solution. The approach is applicable to many problems in physics and combines the inherent precision of this series solution with the flexibility of BEM to describe practical, non-idealized electrode shapes. The resulting lens field in the Fourier series subdomain is of higher precision, thereby allowing smaller errors in subsequent calculations of electron ray paths. The effects of aberrations are thus easier to observe in tracing non-paraxial rays. A significant speed increase in tracing rays is also observed. The modeling technique has been validated by reproducing example ray-traces through

  9. Pulsed Power for a Dynamic Transmission Electron Microscope

    SciTech Connect

    dehope, w j; browning, n; campbell, g; cook, e; king, w; lagrange, t; reed, b; stuart, b; Shuttlesworth, R; Pyke, B

    2009-06-25

    Lawrence Livermore National Laboratory (LLNL) has converted a commercial 200kV transmission electron microscope (TEM) into an ultrafast, nanoscale diagnostic tool for material science studies. The resulting Dynamic Transmission Electron Microscope (DTEM) has provided a unique tool for the study of material phase transitions, reaction front analyses, and other studies in the fields of chemistry, materials science, and biology. The TEM's thermionic electron emission source was replaced with a fast photocathode and a laser beam path was provided for ultraviolet surface illumination. The resulting photoelectron beam gives downstream images of 2 and 20 ns exposure times at 100 and 10 nm spatial resolution. A separate laser, used as a pump pulse, is used to heat, ignite, or shock samples while the photocathode electron pulses, carefully time-synchronized with the pump, function as probe in fast transient studies. The device functions in both imaging and diffraction modes. A laser upgrade is underway to make arbitrary cathode pulse trains of variable pulse width of 10-1000 ns. Along with a fast e-beam deflection scheme, a 'movie mode' capability will be added to this unique diagnostic tool. This talk will review conventional electron microscopy and its limitations, discuss the development and capabilities of DTEM, in particularly addressing the prime and pulsed power considerations in the design and fabrication of the DTEM, and conclude with the presentation of a deflector and solid-state pulser design for Movie-Mode DTEM.

  10. Quantitative phase-sensitive imaging in a transmission electron microscope

    PubMed

    Bajt; Barty; Nugent; McCartney; Wall; Paganin

    2000-05-01

    This paper presents a new technique for forming quantitative phase and amplitude electron images applicable to a conventional transmission electron microscope. With magnetised cobalt microstructures used as a test object, we use electron holography to obtain an independent measurement of the phase shift. After a suitable calibration of the microscope, we obtain quantitative agreement of the phase shift imposed on the 200 keV electrons passing through the sample.

  11. Study of the painting methods of mural paintings in ancient tombs of Goguryeo using scanning electron microscope.

    PubMed

    Han, Kyeongsoon; Lee, Sangjin; Lee, Hwasoo

    2013-08-01

    Disputes on the painting methods of Goguryeo murals can mainly be categorized into whether the murals adapted eastern secco or western fresco; however, the murals have their own unique methods as well. There are different viewpoints among experts on interpreting the painting methods. This study involved the creation of research samples to discover the painting methods under dispute and may help discover the methods based on scanning electron microscopy energy-dispersive X-ray spectroscopy (SEM-EDX) studies. Goguryeo murals introduced pseudo-fresco rather than buon fresco methods. Unlike fresco techniques in the West, Goguryeo painters mixed traditional soft binders and adapted typical secco painting techniques for paintings, borders, and corrections after drying. The disputed issues may be resolved by these techniques, and samples may be produced based on the analyzed data. Therefore, many questions can finally be answered through SEM-EDX elemental mapping. PMID:23920197

  12. Long-spined polymorphic neurons of the medial cortex of lizards: a Golgi, Timm, and electron-microscopic study.

    PubMed

    Lopez-Garcia, C; Martinez-Guijarro, F J; Berbel, P; Garcia-Verdugo, J M

    1988-06-15

    The morphology, ultrastructure, and principal synaptic input of long-spined neurons located in the inner plexiform layer of the medial cortex in three related species of lizards is described. Golgi impregnations have been used to define the external morphology of these neurons and their axonal trajectories. Their most striking characteristic is the presence of very long spines or "microdendrites" especially abundant on the distal dendritic segments. Axons have ascendent trajectories, pass through the cell layer, and ramify in the outer plexiform layer. Combined Golgi-electron microscopy as well as standard electron microscopy permitted the definition of the ultrastructure of these neurons. Timm and sulfide-osmium methods permitted the detection and characterization of their principal synaptic input (i.e., zinc-containing boutons). Gamma aminobutyric acid (GABA)-immunostained sections in one of the species studied allowed the identification of GABA-immunoreactive somata which had the same morphology and ultrastructure as long-spined neurons; these GABA-immunoreactive somata and their processes were found in the same location as long-spined neurons. This suggests that at least some long-spined polymorphic neurons are GABA-ergic and presumably inhibitory. Finally, the neurobiological significance of these long-spined neurons is discussed and briefly compared with that of similar neurons of the hilus of the fascia dentata of the rat.

  13. Circular dichroism in the electron microscope: Progress and applications (invited)

    SciTech Connect

    Schattschneider, P.; Loeffler, S.; Ennen, I.; Stoeger-Pollach, M.; Verbeeck, J.

    2010-05-15

    According to theory, x-ray magnetic circular dichroism in a synchrotron is equivalent to energy loss magnetic chiral dichroism (EMCD) in a transmission electron microscope (TEM). After a synopsis of the development of EMCD, the theoretical background is reviewed and recent results are presented, focusing on the study of magnetic nanoparticles for ferrofluids and Heusler alloys for spintronic devices. Simulated maps of the dichroic strength as a function of atom position in the crystal allow evaluating the influence of specimen thickness and sample tilt on the experimental EMCD signal. Finally, the possibility of direct observation of chiral electronic transitions with atomic resolution in a TEM is discussed.

  14. Age-related intra-axonal accumulation of neurofilaments in the dorsal column nuclei of the cat brainstem: a light and electron microscopic immunohistochemical study.

    PubMed

    Zhang, J H; Sampogna, S; Morales, F R; Chase, M H

    1998-06-29

    In the present study, we examined the age-related intra-axonal accumulation of neurofilaments in the dorsal column nuclei of the cat by using immunohistochemical techniques combined with light and electron microscopy. Light microscopic analysis revealed oval or circular immunostained structures in the dorsal column nuclei of old cats. These immunostained structures were not observed in the material obtained from adult controls. Under the electron microscope, it was discovered that the immunostained structures were greatly enlarged axons with disrupted myelin sheaths. These enlarged axons contained massive accumulations of neurofilaments, some mitochondria, vacuoles and dense granules. The abnormalities of the myelin sheaths included the breaking of myelin at several locations, a splitting and ballooning in the myelin lamellae of the sheath and a distended periaxonal space between the axon and myelin sheaths. These ultrastructural changes resembled the degenerative alterations that have been observed in the axons of human and animals suffering from a number of pathological conditions, including giant axonal neuropathy and toxic neuropathy. Therefore, severely altered axons with intra-axonal accumulation of neurofilaments appear to reflect chronic degenerative changes that are a component of the aging process. PMID:9666164

  15. The nature of the Ag-staining of nucleolus organizer regions. Electron- and light-microscopic studies on human cells in interphase, mitosis, and meiosis.

    PubMed

    Schwarzacher, H G; Mikelsaar, A V; Schnedl, W

    1978-01-01

    Electron micrographs reveal that the Ag-stainable substance is located on the outside of NOR's or around them but not in the chromosomes themselves. In association figures, the Ag-positive material lies between the acrocentric chromosomes. Light-microscopic studies show that the Ag stainability of the nucleolus in interphase is correlated with the function of the NOR, as seen from inactive and activated lymphocytes. Much more Ag-positive material is seen in prophase than in meta- and anaphase. It starts to increase again in late telophase. In male meiosis the NOR's remain Ag-positive until pachytene. First and second metaphase figures are negative. Experiments using RNase, TCA, and trypsin indicate that the Ag-stainable substance is an acidic protein. The precipitation of Ag granules in interphase nuclei seen in the electron microscope is greatest over the fibrillar component of the nucleolus. The most likely interpretation is that the Ag-stainable material is a component of ribonucleic protein accumulating around active NOR's. In mitosis some of this material remains at the NOR's. In first meiosis it is completely removed before diakinesis. PMID:77208

  16. Scanning electron microscopic study of the vascular system in the hemal node of the bovine cervical region.

    PubMed

    Zhang, Weidong; Yasuda, Masahiro; Hosaka, Yoshinao Z; Nasu, Tetsuo

    2013-01-31

    The vasculature of the hemal node (HN) from the bovine cervical region was investigated using a combination of vascular corrosion casting and scanning electron microscopy. A dense vessel network of capsule was found surrounding the cast of HN parenchyma and had no connection with the subcapsular sinus; these vessels converged and exited the HN via the hilar vein. Within the HN, many anastomoses were found between the capillary networks and the surrounding sinuses in the follicular zone and deep cortex. The sinusoid pathway in the HN was characterized by subcapsular sinuses, which were continuous with the trabecular sinuses and tubular sinuses over the parenchyma, and these sinuses finally entered the medullary veins. In our study, direct communications between cortical capillaries and subcapsular sinuses were identified. This may explain the origin of numerous erythrocytes in the HN sinusoids and help to understand lymphocyte migration of the HN.

  17. MRT letter: Spatial distribution of vancomycin-induced damage in Staphylococcus epidermidis biofilm: an electron microscopic study.

    PubMed

    Singh, Rachna; Ray, Pallab; Das, Anindita; Sharma, Meera

    2010-07-01

    This study was planned to elucidate the efficacy of antibiotics on Staphylococcus epidermidis and Staphylococcus aureus biofilms by scanning electron microscopy (SEM). Biofilms of S. epidermidis ATCC 35984 and S. aureus ATCC 29213 were grown on black, polycarbonate membranes placed on tryptic soy agar plates for 48 h at 37 degrees C, and then exposed to vancomycin or amikacin or ciprofloxacin at clinically achievable levels for 24 h at 37 degrees C. The morphology of antibiotic-treated and untreated biofilms was elucidated by SEM. SEM analysis indicated a differential affection of S. epidermidis ATCC 35984 in the center and periphery of biofilm upon treatment with vancomycin. The center of biofilm revealed damaged cells with sparse distribution, smaller size, and irregular shape, whereas cells in the periphery were unaffected. This differential distribution of susceptibility within S. epidermidis ATCC 35984 biofilms was specific for vancomycin only and was not observed on exposure to amikacin or ciprofloxacin. No such response was found in S.aureus ATCC 29213 biofilms. Thus, our study suggests a spatial distribution of vancomycin-induced damage in S. epidermidis biofilms. To our knowledge, this is the first report that indicates a differential affection of S. epidermidis in the center and periphery of biofilm upon treatment with vancomycin. Studies on the factors controlling this differential distribution could provide valuable insights into the mechanisms of antimicrobial resistance in S. epidermidis biofilms.

  18. Transplanted sympathetic neurons from old rats survive in the anterior eye chamber: a histochemical and electron microscopic study.

    PubMed

    Suhonen, J; Hervonen, A

    1993-01-01

    The purpose of this study was to investigate the viability and ultrastructural characteristics of intraocular superior cervical ganglion (SCG) grafts from young (3 months), aged (24 months) and very old (36 months) rats after short-term (1 month) grafting. The formaldehyde-induced fluorescence (FIF) technique for histochemical demonstration of catecholamines was used to indicate the functionality of transplanted neurons. Ultrastructural changes in grafts were demonstrated by electron microscopy. Four weeks after transplantation, catecholamine histofluorescence in young transplants was almost as strong as in the intact ganglia, while aged and very old grafts showed decreased fluorescence and contained a marked accumulation of autofluorescent lipopigment bodies. Catecholamine histofluorescence showed a decrease in neuronal density of 47%, 59% and 68% in young, aged and very old grafted ganglia, respectively. The shape of most of the transplanted neurons did not differ from that in the intact ganglia, but the average diameter of neurons was decreased after grafting. In electron microscopy, both neurons with normal in vivo fine structure and neurons showing some abnormal cytological alterations were seen in each age group of the transplants. The most prominent feature after grafting was the accumulation of different types of lipopigment bodies in the perikarya of neurons. the organization of the rough endoplasmic reticulum was more irregular in transplanted neurons than in intact neurons. In addition, the amount of neurofilament aggregates increased and some mitochondria were swollen in neurons after transplantation. These results suggest that young sympathetic ganglion tissue survives rather well after transplantation into the anterior eye chamber, while in the aged sympathetic ganglion implants the survival rate is poorer. However, aged and very old SCG grafts were shown to contain and continue to produce noradrenaline, indicating that sympathetic neurons maintain

  19. Protective Role of Ramipril and Candesartan against Myocardial Ischemic Reperfusion Injury: A Biochemical and Transmission Electron Microscopical Study

    PubMed Central

    Reddy, Rajitha Bodd; Punuru, Priyanka; Chakka, Gopinath; Karunakaran, Gauthaman

    2016-01-01

    The present study was designed to investigate the role of combined administration of Ramipril and Candesartan against in vitro myocardial ischemic reperfusion injury in rat. Male Wistar albino rats were divided into five groups (n = 6) and treated with saline (10 mL/kg), Ramipril (2 mg/kg), Candesartan (1 mg/kg), and the combination of both drugs, respectively 24 h before induction of global ischemia (5 min of stabilization, 9 min of global ischemia, and 12 min of reflow). Combination of Ramipril and Candesartan when compared to the monotherapy significantly increased the levels of superoxide dismutase, reduced glutathione, catalase, and nitric oxide and decreased the levels of thiobarbituric acid reactive substances. In addition, the superior protective role of combination of Ramipril and Candesartan on ischemia induced myocardial damage was further confirmed by well preserved myocardial tissue architecture in light microscopy and transmission electron microscopy analysis studies. The combination was proved to be effective in salvaging the myocardial tissue against ischemic reperfusion injury when compared to the monotherapy of individual drugs and further investigations on protective mechanism of drugs by increasing the nitric oxide level at molecular levels are needed. PMID:27042175

  20. Transmission electron microscope study of fusion-environment radiation damage in iron and iron-chromium alloys

    SciTech Connect

    Horton, L.L.S.

    1982-07-01

    A transmission electron microscopy study of radiation damage microstructures in iron and iron-chromium alloys has been performed. This study consisted of both qualitative and quantitative characterization of the dislocation and cavity microstructures, including determination of vacancy/interstitial character and Burgers vectors for dislocation loops and analysis of the cavity morphology. The effects of irradiation temperature, fluence, helium implantation, and chromium content were investigated. Neutron irradiation (iron specimens, 1 dpa, 455 to 1000 K) and triple-beam ion irradiation (Fe-10% Cr specimens, 10 dpa, 725 to 950 K; Fe-10% Cr specimens, 850 K, 0.3 to 100 dpa; and Fe, Fe-5% Cr, Fe-10% Cr specimens, 850 K, 10 dpa) were employed. In the triple-beam ion irradiation procedure, simultaneous bombardment with 4 MeV Fe/sup + +/ ions and energetic He/sup +/ and D/sub 2//sup +/ ions was used to simulate the fusion environment (10 at. ppM He/dpa and 41 at. ppM D/dpa). In addition, single-beam 4 MeV Fe/sup + +/ ion irradiations of Fe-10% Cr both with and without pre-injection of helium and deuterium were performed.

  1. A Descriptive in vitro Electron Microscopic Study of Acidic Fluoride-Treated Enamel: Potential Anti-Erosion Effects.

    PubMed

    Hjortsjö, Carl; Young, Alix; Kiesow, Andreas; Cismak, Andreas; Berthold, Lutz; Petzold, Matthias

    2015-01-01

    This study aimed to investigate the surface zones of acidic fluoride-treated enamel. Human teeth were each divided into three or four enamel specimens that were treated for 10 min with solutions of 0.2 and 0.4% HF (pH 3.09 and 2.94), 1.74% SnF2 (pH 2.9), 0.68% TiF4 (pH 1.6) and 0.84% NaF (pH 4.5). Untreated specimens functioned as negative controls. The microstructure and elemental composition of the surface zones were studied by scanning electron microscopy/energy-dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and nanospot-EDX following cross-sectional preparation using focused ion beam technology. TEM/EDX analyses of NaF-treated specimens showed a 500-nm-thick closed surface film containing 20-40 at% (atomic percent) F. HF-treated specimens had a distinct surface film 200-600 nm thick (dense, not globular) containing 45-47 at% F. TiF4-treated specimens had a surface film of 200-300 nm in thickness containing 8-11 at% Ti but no detectable fluoride. SnF2-treated specimens had a modified surface enamel layer varying in thickness from 200 to 800 nm with an inhomogeneous distribution of Sn. Local spots were detected with as high as 8 at% Sn (30 wt%, weight percent). The results suggest that the reaction mechanisms of SnF2 and TiF4 solutions with dental enamel differ from those occurring after enamel exposure to acidulated NaF and HF solutions. While the HF and NaF treatments resulted in the formation of CaF2-like material as shown by EDX, no significant surface fluoridation was found for SnF2 and TiF4 solutions within the TEM/EDX detection limits. These results suggest that the erosion-protective mechanisms of these latter compounds probably relate more to the formation of hardly soluble and acid-resistant reaction surface films and less to surface fluoride incorporation.

  2. A Descriptive in vitro Electron Microscopic Study of Acidic Fluoride-Treated Enamel: Potential Anti-Erosion Effects.

    PubMed

    Hjortsjö, Carl; Young, Alix; Kiesow, Andreas; Cismak, Andreas; Berthold, Lutz; Petzold, Matthias

    2015-01-01

    This study aimed to investigate the surface zones of acidic fluoride-treated enamel. Human teeth were each divided into three or four enamel specimens that were treated for 10 min with solutions of 0.2 and 0.4% HF (pH 3.09 and 2.94), 1.74% SnF2 (pH 2.9), 0.68% TiF4 (pH 1.6) and 0.84% NaF (pH 4.5). Untreated specimens functioned as negative controls. The microstructure and elemental composition of the surface zones were studied by scanning electron microscopy/energy-dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and nanospot-EDX following cross-sectional preparation using focused ion beam technology. TEM/EDX analyses of NaF-treated specimens showed a 500-nm-thick closed surface film containing 20-40 at% (atomic percent) F. HF-treated specimens had a distinct surface film 200-600 nm thick (dense, not globular) containing 45-47 at% F. TiF4-treated specimens had a surface film of 200-300 nm in thickness containing 8-11 at% Ti but no detectable fluoride. SnF2-treated specimens had a modified surface enamel layer varying in thickness from 200 to 800 nm with an inhomogeneous distribution of Sn. Local spots were detected with as high as 8 at% Sn (30 wt%, weight percent). The results suggest that the reaction mechanisms of SnF2 and TiF4 solutions with dental enamel differ from those occurring after enamel exposure to acidulated NaF and HF solutions. While the HF and NaF treatments resulted in the formation of CaF2-like material as shown by EDX, no significant surface fluoridation was found for SnF2 and TiF4 solutions within the TEM/EDX detection limits. These results suggest that the erosion-protective mechanisms of these latter compounds probably relate more to the formation of hardly soluble and acid-resistant reaction surface films and less to surface fluoride incorporation. PMID:26536617

  3. Room temperature electron transport properties of single C{sub 60} studied using scanning tunneling microscope and reak junctions.

    SciTech Connect

    Cheng, R.; Carvell, J.; Fradin, F. Y.; Indiana Univ.-Purdue Univ. at Indianapolis

    2010-09-15

    We report the measurements of the electron transport of an individual C{sub 60} molecule through the combination of two experimental efforts. The nanometer-sized junctions were fabricated using electromigration combined with electron beam lithography and shadow effect evaporation. We performed the scanning tunneling microscopy/spectroscopy measurements of dispersed C{sub 60} molecules which were deposited on a highly ordered pyrolytic graphite substrate. The single electron tunneling through a single C{sub 60} molecule due to the Coulomb blockage effect is observed at room temperature.

  4. Coated-vesicle shells, particle/chain material, and tubulin in brain synaptosomes. An electron microscope and biochemical study

    PubMed Central

    1976-01-01

    Coated vesicles (CVs), plain synaptic vesicles (PSVs), and nonvesicular flocculent material were isolated from synaptosomes and examined with goniometry and high-resolution electron microscopy after either negative staining or various biochemical procedures. The flocculent material (i.e. the presynaptic matrix material except CV shells) is largely composed of particulate or elongated (chainlike) structures; some of this material (here referred to as particle/chain material) is attached to PSVs. The results obtained were: (a) the proteinaceous properties of the CV coat (also referred to as CV shell) and the particle/chain material were demonstrated with chymotrypsin; (b) the CV shell, studied with various negative-staining techniques, differs from the particle/chain material since it has no 3-4-nm globular subunits and reacts differently to alkaline pH; (c) the particle/chain material consists of aggregates of 3-4-nm globular subunits, four of which yield 8-10-nm fine particles; and these particles can be further aggregated into chains 8-10 nm wide and up to 30-60 nm long showing a "hollow" core; (d) vinblastine sulfate induced ringlike or helical crystalloid precipitates closely resembling the vinblastine-induced microtubule crystals reported in the literature, but vinblastine had no effect on either the CV shell material or the particle/chain material. PMID:57963

  5. HSV hepatitis in the mouse: a light and electron microscopic study with immunohistology and in situ hybridization.

    PubMed

    Schirmacher, P; Wörsdörfer, M; Lübbe, K; Falke, D; Thoenes, W; Dienes, H P

    1989-01-01

    In order to characterize better the morphology and immune response in acute necrotizing HSV infection, murine HSV hepatitis was examined. BALB/c mice were inoculated intraperitoneally with 10(6) plaque-forming units (PFU) of HSV-1 (Lenette) and HSV-2 (D316). In both groups half the animals were pretreated with silica particles to block macrophage function. Up to 6 days after infection four mice from each group were sacrificed at daily intervals and the livers were examined by light and electron microscopy, immunohistology, in situ hybridization, combined immunohistology/in situ hybridization and titration of viral PFU. HSV-2 infected mice developed severe necrotizing hepatitis with persistence of HSV in the liver tissue until the end of the study. HSV-1 infected mice rapidly eliminated the virus and revealed only small necrotic foci. Early phase alterations and necrotic phase lesions were distinguished and characterized and morphologic evidence of a direct cytopathic effect of HSV was detected. A specific immune reaction in late stages appeared to be mediated by T4-positive T-lymphocytes. In situ hybridization and immunohistochemistry showed a close correlation with virus titration and were valuable in characterizing early phases and in the assessment of prognosis and differential diagnosis.

  6. The fine structure of the human fetal urinary bladder. Development and maturation. A light, transmission and scanning electron microscopic study.

    PubMed Central

    Newman, J; Antonakopoulos, G N

    1989-01-01

    The urinary bladders of 27 human fetuses, aged 7 weeks to full term, were studied by light, transmission and scanning electron microscopy to establish the sequence of events in the development and maturation of the organ during fetal life. In the early specimens, 7-12 weeks old, the urinary bladder was lined by a bilayered, cuboidal and glycogen-rich epithelium. During the 13-17th weeks the epithelium thickened, a third layer developed and by light microscopy it now resembled urothelium. By 21 weeks this had evolved into a 3-4 layer thick epithelium with typical ultrastructural urothelial characteristics. Smooth muscle cells emerged from the condensed mesenchyme of the bladder wall by the 12th week of gestation, initially in the cephalic part of the organ but spreading within a week into the caudal end. Our findings indicate that the human fetal bladder undergoes a series of vital developmental changes during 13-21 weeks of gestation finally acquiring the typical urothelial lining and a well-developed muscular coat. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16 Fig. 17 PMID:2621133

  7. Surface ultrastructure of the cornea and adjacent epidermis during metamorphosis of Rana pipiens: a scanning electron microscopic study

    SciTech Connect

    Kaltenbach, J.C.; Harding, C.V.; Susan, S.

    1980-01-01

    The external surface of the cornea and adjacent epidermis of larvae in representative developmental stages and of adult frogs, Rana pipiens, was studied by scanning electron microscopy. Surface cells are polygonal, usually hexagonal, in outline and covered with microprojections. During larval development prior to metamorphic stages, neither eyelids nor Harderian glands have developed; microprojections on the corneal surface are high and branched, and cell boundaries are elevated. On the anterior portion of the cornea and on the epidermis near the eye, the surface pattern is less dense, and ciliated cells are present. During metamorphic stages, corneal cell boundaries become less prominent and the pattern of microprojections more variable and markedly different from that of larvae of earlier stages. Corneal cells have a spongy appearance, are covered by a coating material, or are characterized as light or dark based on their brightness and surface texture. As eyelids develop in metamorphic stages XX-XXI, the numbers of ciliated cells increase dramatically, both on the corneal surface and on the edges of the developing lids. In later metamorphic stages XXII to XXV, lids and Harderian glands become well-developed, and cilia are no longer observed. The adjacent epidermal surface becomes devoid of cilia but perforated by openings of cutaneous glands. Its spongy appearance is similar to that of both the cornea and neighboring epidermis of the mature frog. Changes in corneal surface features are probably metamorphic events associated with development of lids and Harderian glands and a shift from an aqueous to an air environment.

  8. Antennulary sensory organs in cyprids of Octolasmis and Lepas (Crustacea: Thecostraca: Cirripedia: Thoracica): a scanning electron microscopic study.

    PubMed

    Blomsterberg, Mikkel; Høeg, Jens T; Jeffries, William B; Lagersson, Niklas C

    2004-05-01

    Cypris larvae of the pedunculate barnacles Octolasmis angulata (Poecilasmatidae), Lepas australis, L. pectinata, and Dosima fascicularis (Lepadidae) were studied with scanning electron microscopy, focusing on the sensory setae and the attachment disc on the antennules. The antennules of O. angulata did not exhibit any remarkable trait, but carry the same number of setae as seen in most other thoracicans. The third segment is bell-shaped and quite distinct from the second and its attachment disc is surrounded by a skirt. We found several potential synapomorphies in antennulary morphology between cyprids of the lepadid species but none of them were shared with the cyprids of Octolasmis; the list of unique lepadid characters includes: one additional, preaxial seta on the second segment; multiple similar (up to eight) postaxial setae (PS3) on the third segment, unlike all other thoracicans, where there is only a single PS3; the third segment consists almost entirely of the attachment disc, which is distended and surrounded by two parallel rows of radial setae; on the fourth segment the terminal seta E is diminutive. We found no traits in cyprids of Octolasmis that seem to be adaptations to their attachment site within the branchial chamber of swimming crabs and, in particular, no similarities with cyprids of rhizocephalan barnacles, many of which also attach in the gill chamber. The synapomorphies between cyprids of the lepadid species may be adaptations to their life in the neuston.

  9. Confocal laser scanning and electron microscopical studies on osmoregulatory epithelia in the branchial cavity of the lobster homarus gammarus

    PubMed

    Haond; Flik; Charmantier

    1998-06-01

    The adult lobster Homarus gammarus is a weak hyper-regulator at low salinity. The objective of this study was to locate the ion-transporting tissues in the branchial chamber of this species, using electron microscopy and confocal laser scanning microscopy with a fluorescent vital stain for mitochondria, DASPMI, which is widely used to locate mitochondria-rich cells in ion-transporting epithelia of fish. A thick mitochondria-rich epithelium is present on the inner side of the branchiostegite and over the entire surface of the epipodites. Ultrastructural observations confirm that this tissue has features typical of an ion-transporting epithelium. When the lobster is transferred to low salinity, these epithelia undergo marked ultrastructural changes, such as an increase in thickness related to the development of basolateral infoldings, the appearance of numerous vesicles and an increase in height of the apical microvilli. In the gills, the branchial filaments are lined by a thin and poorly differentiated epithelium, containing numerous mitochondria; no significant ultrastructural changes were observed in the gills of animals acclimated to low salinity. In summary, in H. gammarus, no evidence of osmoregulatory structures was found in the gills. Differentiated ion-transporting epithelia are present in the branchial cavity, on the inner side of the branchiostegite and on the epipodites; these organs are probably involved in osmoregulation. PMID:9576892

  10. A scanning electron-microscopic study of the local degeneration of cilia during sexual reproduction in Paramecium.

    PubMed

    Watanabe, T

    1978-08-01

    The location and extent of local degeneration of cilia during sexual reproduction of Paramecium was studied using scanning electron microscopy to examine cells undergoing conjugation and autogamy. At some time during the mating reaction, but prior to conjugant pair formation, ciliary degeneration begins at the antero-ventral tip of cells and proceeds posteriorly along the suture. In the anterior part of the cell, degeneration occurs on both sides of the suture, but in the posterior part it is restricted to the right side of the suture. In 5 species of Paramecium examined, degeneration occurred in nearly the same region. No degeneration of cilia is observed in natural autogamy of P. tetraurelia, whereas in chemically induced autogamy of P. caudatum degeneration occurs as in ordinary conjugation. Conjugant pairs never expose any deciliated cell surface except at the postero-ventral tip. The maximum extent of ciliary degeneration is best seen in the chemically induced autogamous cells: 7 kinetics (rows of unit teritories) at the anterior-left, 4 kinetics at the anterior-right, 10 or more kinetics at the posterior-right and the right wall of the vestibule of the mouth. Before complete disappearance of the cilia, many short cilia are observed. This suggests that ciliary degeneration is due to resorption. Degeneration extends more rapidly in cells with stronger mating reactivity. The relations between mating reactivity, ciliary degeneration and nuclear activation are discussed. PMID:701405

  11. Immunocytochemical light- and electron-microscopic studies of growth hormone, prolactin and somatomammotroph cells in female goat.

    PubMed

    Vásquez, F; Gómez, M A; Serrano, J; Bernabé, A

    2002-01-01

    We have studied the structural and ultrastructural changes that occur in growth hormone (GH), prolactin (PRL) and somatomammotroph (SMT) cells of female goats of the Murciano-Granadina breed during different physiological stages: prepuberty, anestrus, pregnancy and lactation. Serial sections were stained with double immunolabeling, alkaline phosphatase and avidin-biotin complex for light microscopy, and immunogold labeling was used for electron microscopy. These techniques allowed the identification of GH, PRL and SMT cells, which were evenly distributed throughout the whole pars distalis. PRL cells were the most frequent. Both PRL and GH cells showed morphological changes that may be related to a given physiological stage. These changes include the number of cells and the number and size of the secretory granules. SMT cells were clearly identified by having two types of monohormonal secretory granule showing single labeling, in spite of their similar ultrastructural characteristics to the other adenohypophysary cells. They are found in low percentages (0.6%). We postulate that cell aggregates which look like SMT syncytia may be artifacts caused by interdigitation of PRL and GH cells, and that cells which are normally taken to be SMT cells are not an interconversion stage between monohormonal cells.

  12. A Light and Scanning Electron Microscopic Study of the Closing Apparatus in Tintinnid Ciliates (Ciliophora, Spirotricha, Tintinnina): A Forgotten Synapomorphy

    PubMed Central

    AGATHA, SABINE

    2011-01-01

    A membranous closing apparatus shuts the lorica opening in disturbed tintinnids of six genera belonging to four families. The homology of the apparatuses is investigated, using data from the literature and Mediterranean tintinnids studied in vivo and by scanning electron microscopy. Morphological and functional similarities indicate that the foldable closing apparatus is not only a synapomorphy of the genera Codonella (Codonellidae) and Dictyocysta (Dictyocystidae), as suggested 80 years ago, but also of Codonaria (Codonellidae) and Codonellopsis (Codonellopsidae). In Codonaria, Codonella, and Dictyocysta, the apparatuses merge posteriorly into membranous lorica sacs, which probably represent homologous structures. The diagnoses of these genera are improved according to the new findings. The close relationship of Codonella, Codonellopsis, and Dictyocysta is also inferred from small subunit rRNA phylogenies and the ultrastructure of the capsules. It contradicts the current lorica-based classification of the tintinnids. The assumption that the diaphragm-like apparatus in the genera Salpingacantha and Salpingella is not homologous to the foldable ones in the genera mentioned above is supported by molecular and cytological features. PMID:20584102

  13. How to operate a cryo-electron microscope.

    PubMed

    Sun, Jingchuan; Li, Huilin

    2010-01-01

    We describe the basic principles for imaging frozen-hydrated specimens in a transmission electron microscope and provide a step-by-step guide to a new user, from starting up and aligning the microscope, to loading a cryo-grid into the specimen holder and inserting the holder into the microscope, to setting up the low dose mode for imaging, and eventually to shutting down the microscope. The procedure is based on a JEOL TEM; however, it is applicable to microscopes from other manufacturers with small modifications. We also give several tips on how to minimize specimen exposure before taking pictures; how to minimize the specimen drift and charging during exposure; how to estimate the thickness of the vitreous ice, and how to quickly estimate the electron exposure dose. Despite recent advances in instrumentation, the microscopist's patience and attention to detail may still be the key to acquiring a high quality cryo-electron micrograph. PMID:20887860

  14. Observation of Dislocation Dynamics in the Electron Microscope

    SciTech Connect

    Lagow, B W; Robertson, I M; Jouiad, M; Lassila, D H; Lee, T C; Birnbaum, H K

    2001-08-21

    Deformation experiments performed in-situ in the transmission electron microscope have led to an increased understanding of dislocation dynamics. To illustrate the capability of this technique two examples will be presented. In the first example, the processes of work hardening in Mo at room temperature will be presented. These studies have improved our understanding of dislocation mobility, dislocation generation, and dislocation-obstacle interactions. In the second example, the interaction of matrix dislocations with grain boundaries will be described. From such studies predictive criteria for slip transfer through grain boundaries have been developed.

  15. Observation of dislocation dynamics in the electron microscope

    SciTech Connect

    Lagow, B W; Robertson, I M; Jouiad, M; Lassila, D H; Lee, T C; Birnbaum, H K

    2001-01-17

    Deformation experiments performed in-situ in the transmission electron microscope have led to an increased understanding of dislocation dynamics. To illustrate the capability of this technique two examples will be presented. In the first example, the processes of work hardening in Mo at room temperature will be presented. These studies have improved our understanding of dislocation mobility, dislocation generation, and dislocation-obstacle interactions. In the second example, the interaction of matrix dislocations with grain boundaries will be described. From such studies predictive criteria for slip transfer through grain boundaries have been developed.

  16. The Scanning Electron Microscope and the Archaeologist

    ERIC Educational Resources Information Center

    Ponting, Matthew

    2004-01-01

    Images from scanning electron microscopy are now quite common and they can be of great value in archaeology. Techniques such as secondary electron imaging, backscattered electron imaging and energy-dispersive x-ray analysis can reveal information such as the presence of weevils in grain in Roman Britain, the composition of Roman coins and the…

  17. The three-dimensional feto-maternal vascular interrelationship during early bovine placental development: a scanning electron microscopical study

    PubMed Central

    PFARRER, CHRISTIANE; EBERT, BRIGITTE; MIGLINO, MARIA ANGELICA; KLISCH, KARL; LEISER, RUDOLF

    2001-01-01

    Both the fetal and maternal microvasculature of bovine placentomes was examined by scanning electron microscopy of vascular casts. So far the development of the vascular architecture of the bovine placentome in early gestation has only been studied 2-dimensionally due to technical difficulties arising from the fragility of the early placental blood vessels. Repeated experiments led to the selection of the microvascular corrosion casts presented here. The vasculature of the maternal compartment is supplied by large caruncular stalk or spiral arteries, which release short maternal stem arteries. In the 3rd month of gestation, these arteries branch into several arterioles at their base, thus providing the vascular framework for the lower part of the septal walls of the primary crypts. In the 4th month, due to progressive longitudinal growth of the stem arteries, branching into arterioles occurs not only at the base, but over the whole length of the stem arteries. These arterioles supply the capillary complexes of the septa which resemble the major part of the septal vasculature and face the secondary crypts. Further indentation results in the formation of tertiary crypt capillary complexes, encircling the earlier secondary unit. From the 6th month of gestation the architecture resembles the fully developed maternal placenta with stem arteries running directly to the fetal side to branch into 4 to 6 arterioles, which turn back to enter secondary and tertiary septa. Maternal venules, collecting the blood from the capillary bed of secondary and tertiary septa, converge onto stem veins leaving the caruncle via branches of the uterine vein. The fetal part of the placentome is supplied by the cotyledonary arteries, which branch into fetal stem arteries that are the tributary to single villous trees. Over their whole course towards the maternal side, these give off arterioles entering secondary villi. The tertiary or terminal villous vasculature consists of capillaries

  18. Observation of Materials Processes in Liquids in the Electron Microscope

    SciTech Connect

    Wang, Chong M.; Liao, Honggang; Ross, Frances M.

    2015-01-01

    Materials synthesis and the functioning of devices often indispensably involve liquid media. But direct visualization of dynamic process in liquids, especially with high spatial and temporal resolution, has been challenging. For solid materials, advances in aberration corrected electron microscopy have made observation of atomic level features a routine practice. Here we discuss the extent to which one can take advantage of the resolution of modern electron microscopes to image phenomenon occuring in liquids. We will describe the fundamentals of two different experimental approaches, closed and open liquid cells. We will illustrate the capabilities of each approach by considering processes in batteries and nucleation and growth of nanoparticles from solution. We conclude that liquid cell electron microscopy appears to be duly fulfilling its role for in situ studies of nanoscale processes in liquids, revealing physical and chemical processes otherwise difficult to observe.

  19. Microcircuit testing and fabrication, using scanning electron microscopes

    NASA Technical Reports Server (NTRS)

    Nicolas, D. P.

    1975-01-01

    Scanning electron microscopes are used to determine both user-induced damages and manufacturing defects subtle enough to be missed by conventional light microscopy. Method offers greater depth of field and increased working distances.

  20. Correlative scanning electron, transmission electron, and light microscopic studies of the in vitro development of mouse embryos on a plastic substrate at the implantation stage.

    PubMed

    Gonda, M A; Hsu, Y C

    1980-04-01

    Correlative scanning electron, transmission electron, and light microscopy were utilized to study the morphogenic events occurring during mouse blastocyst outgrowth and early-egg-cylinder development in vitro. After hatching and attachment of blastocysts on the plastic surface, the blastocoelic cavity collapses as the mural trophoblasts spread and migrate outward. The inner cell mass is covered with a differentiated endoderm on the blastocoelic cavity side and by the polar trophoblasts on the medium side at this stage. As the endoderm-covered inner cell mass proliferates, being physically restricted from further downward expansion by the plastic coverslip and by lack of space in the collapsed blastocoelic cavity, it migrates upward and protrudes into the culture medium in a break between the polar and mural trophoblast cells. Polar trophoblast cells apposed to the base of the egg cylinder continue to proliferate forming the ectoplacental cone. Thus, the early egg cylinder lacking a trophoblast barrier begins inverting its growth pattern from towards the culture dish surface to a more upright position. Egg-cylinder development in vitro from the inner cell mass and polar trophoblast cells closely paralleled in vivo. The functional nature of various embryonic cell types observed in these embryos was revealed by scanning electron microscopy. These studies as well as those of Wiley and Pedersen (1977) suggest that blastocysts can serve as a source of in vitro developing early mouse egg cylinders that appear to resemble their in vivo counterparts and can be used in experimental studies of mouse embryogenesis.

  1. Quantification of the Information Limit of Transmission Electron Microscopes

    SciTech Connect

    Barthel, J.; Thust, A.

    2008-11-14

    The resolving power of high-resolution transmission electron microscopes is characterized by the information limit, which reflects the size of the smallest object detail observable with a particular instrument. We introduce a highly accurate measurement method for the information limit, which is suitable for modern aberration-corrected electron microscopes. An experimental comparison with the traditionally applied Young's fringe method yields severe discrepancies and confirms theoretical considerations according to which the Young's fringe method does not reveal the information limit.

  2. Simultaneous specimen and stage cleaning device for analytical electron microscope

    DOEpatents

    Zaluzec, Nestor J.

    1996-01-01

    An improved method and apparatus are provided for cleaning both a specimen stage, a specimen and an interior of an analytical electron microscope (AEM). The apparatus for cleaning a specimen stage and specimen comprising a plasma chamber for containing a gas plasma and an air lock coupled to the plasma chamber for permitting passage of the specimen stage and specimen into the plasma chamber and maintaining an airtight chamber. The specimen stage and specimen are subjected to a reactive plasma gas that is either DC or RF excited. The apparatus can be mounted on the analytical electron microscope (AEM) for cleaning the interior of the microscope.

  3. Light and electron microscopic studies of the intestinal epithelium in Notoplana humilis (Platyhelminthes, Polycladida): the contribution of mesodermal/gastrodermal neoblasts to intestinal regeneration.

    PubMed

    Okano, Daisuke; Ishida, Sachiko; Ishiguro, Sei-ichi; Kobayashi, Kazuya

    2015-12-01

    Some free-living flatworms in the phylum Platyhelminthes possess strong regenerative capability that depends on putative pluripotent stem cells known as neoblasts. These neoblasts are defined based on several criteria, including their proliferative capacity and the presence of cellular components known as chromatoid bodies. Polyclads, which are marine flatworms, have the potential to be a good model system for stem cell research, yet little information is available regarding neoblasts and regeneration. In this study, transmission electron microscopy and immunostaining analyses, using antibodies against phospho-histone H3 and BrdU, were used to identify two populations of neoblasts in the polyclad Notoplana humilis: mesodermal neoblasts (located in the mesenchymal space) and gastrodermal neoblasts (located within the intestine, where granular club cells and phagocytic cells are also located). Light and electron microscopic analyses also suggested that phagocytic cells and mesodermal/gastrodermal neoblasts, but not granular club cells, migrated into blastemas and remodeled the intestine during regeneration. Therefore, we suggest that, in polyclads, intestinal regeneration is accomplished by mechanisms underlying both morphallaxis (remodeling of pre-existing tissues) and epimorphosis (de novo tissue formation derived from mesodermal/gastrodermal neoblasts). Based on the assumption that gastrodermal neoblasts, which are derived from mesodermal neoblasts, are intestinal stem cells, we propose a model to study intestinal regeneration.

  4. Light and scanning electron microscopic study on the tongue and lingual papillae of the common hippopotamus, Hippopotamus amphibius amphibius.

    PubMed

    Yoshimura, Ken; Hama, Natsuki; Shindo, Junji; Kobayashi, Kan; Kageyama, Ikuo

    2009-07-01

    We observed the three-dimensional structures of the external surface and connective tissue cores CTCs, after exfoliation of the epithelium of the lingual papillae (filiform, fungiform, and foliate papillae) of the common hippopotamus (Hippopotamus amphibius amphibius) using scanning electron microscopy and conventional light microscopy. Following unique features were found; typical vallate papillae with a circumferential furrow were not observable. Instead, numerous large fungiform papillae were rather densely distributed on the posterior of the lingual prominence. Taste buds were observable only on the dorsal epithelium. Serous lingual gland was not seen in the lamina propria; however, mucous-rich mixed lingual glands were found and in a few of orifices were seen on the large fungiform tops. Lingual prominence was diminished their width. Rather long and slender conical papillae were distributed on the lingual prominence and were similar to nonruminant herbivore, that is donkey. Beside this narrow lingual prominence, lateral slopes were situated with numerous short spine-like protrusions. After removal of the epithelium, CTCs of lateral slopes exhibited attenuated flower bud structures. Large-conical papillae were situated on the root of the tongue. These large conical papillae were not seen among ruminants and seen on the lingual root of omnivores and carnivores. It implies that lingual structure of common hippopotamus possessed mixed characteristics between Perissodactyls, Ruminantia, and nonherbivores such as Suiformes because of their unique evolutionally taxonomic position. Moreover, adaptation for soft grass diet and associating easier mastication may be also affecting these mixed morphological features of the tongue.

  5. In situ Scanning electron microscope study and microstructural evolution of nano silicon anode for high energy Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Hovington, P.; Dontigny, M.; Guerfi, A.; Trottier, J.; Lagacé, M.; Mauger, A.; Julien, C. M.; Zaghib, K.

    2014-02-01

    In situ and ex situ scanning electron microscopy of nano Si and SiO anode particles was carried out during the first cycles, and at various stages of charge. The particle size effects were explored in the range 0.1-20 μm, providing a new insight into the micro-structural evolution of the particles as a function of their size, and into the 'mechanical' resistance upon important volume change upon phase transformation of these anodes. For small particles, the failure of the battery comes from an electrochemical sintering that compacts the whole electrode, which results in its cracking. The particles keep their integrity when the discharge is stopped at a voltage 0.1 V, which corresponds to the chemical composition Li12Si7, while the particles are known to crack at deeper discharge up to Li22Si5. Replacing the Si particles by SiO particles in an attempt to avoid these structural effects did not help, because of the different chemical reactions during cycling, with the loss of oxygen.

  6. Light and scanning electron microscopic study on the tongue and lingual papillae of the common hippopotamus, Hippopotamus amphibius amphibius.

    PubMed

    Yoshimura, Ken; Hama, Natsuki; Shindo, Junji; Kobayashi, Kan; Kageyama, Ikuo

    2009-07-01

    We observed the three-dimensional structures of the external surface and connective tissue cores CTCs, after exfoliation of the epithelium of the lingual papillae (filiform, fungiform, and foliate papillae) of the common hippopotamus (Hippopotamus amphibius amphibius) using scanning electron microscopy and conventional light microscopy. Following unique features were found; typical vallate papillae with a circumferential furrow were not observable. Instead, numerous large fungiform papillae were rather densely distributed on the posterior of the lingual prominence. Taste buds were observable only on the dorsal epithelium. Serous lingual gland was not seen in the lamina propria; however, mucous-rich mixed lingual glands were found and in a few of orifices were seen on the large fungiform tops. Lingual prominence was diminished their width. Rather long and slender conical papillae were distributed on the lingual prominence and were similar to nonruminant herbivore, that is donkey. Beside this narrow lingual prominence, lateral slopes were situated with numerous short spine-like protrusions. After removal of the epithelium, CTCs of lateral slopes exhibited attenuated flower bud structures. Large-conical papillae were situated on the root of the tongue. These large conical papillae were not seen among ruminants and seen on the lingual root of omnivores and carnivores. It implies that lingual structure of common hippopotamus possessed mixed characteristics between Perissodactyls, Ruminantia, and nonherbivores such as Suiformes because of their unique evolutionally taxonomic position. Moreover, adaptation for soft grass diet and associating easier mastication may be also affecting these mixed morphological features of the tongue. PMID:19548302

  7. Electron microscope studies of the in vitro phagocytosis of Mycobacterium spp. by rainbow trout Oncorhynchus mykiss head kidney macrophages.

    PubMed

    Chen, S C; Adams, A; Thompson, K D; Richards, R H

    1998-03-01

    The cytological response of rainbow trout Oncorhynchus mykiss head kidney macrophages to ingested Mycobacterium spp. was examined in vitro. Mycobacterium marinum or Mycobacterium sp. TB267 isolated from snakehead fish Channa striata Bloch were opsonised with either fresh rainbow trout serum, serum which had been heat-inactivated, or rainbow trout antiserum against the extracellular products (ECP) of the 2 Mycobacterium spp. A monoclonal antibody against the ECP was also used as an opsonin. Suspensions of macrophages were prepared (1 ml of 1 x 10(7) cells ml-1), mixed with the opsonised bacteria (100 microliters of 2 x 10(9) ml-1), and incubated at 18 degrees C for 0.5, 1, 2, 4 or 6 h to allow phagocytosis to occur. A quantitative evaluation of the phagocytosis of the mycobacteria by the macrophages was carried out by electron microscopy. Macrophage phagosomes and their contents were examined and numbers of intact and partially degraded bacteria determined. Pre-labelling dense granules (secondary lysosomes) with ferritin enabled phagosome lysosome fusion to be identified and their frequency determined. Opsonisation of the mycobacteria was found to greatly enhance the phagocytic and killing activity of the rainbow trout macrophages. PMID:9676251

  8. The blood vascular architecture of the salamander external gill: a scanning electron microscopic study of corrosion casts.

    PubMed

    Kato, S; Kurihara, K

    1989-10-01

    The blood vascular architecture in three-paired external gills of salamander tadpoles, Hynobius dunni Tago, was demonstrated with special reference to metamorphosis by scanning electron microscopy of vascular corrosion casts. In the fully developed gill, each of the three-paired afferent branchial arteries gave off secondary afferent filament arterioles. The afferent filament arteriole drained toward the efferent filament arteriole, forming the loop at the posterior extremity of the gill filament. The branched capillaries from the afferent filament arteriole formed two plates of respiratory capillary networks with irregular honeycomb-shaped meshes. In addition, there were non-respiratory shunts as bypass of the blood circulation between the afferent and efferent branchial arteries without branching filament arterioles. Furthermore, the deep venous plexus and subepithelial capillary plexus were seen around each efferent branchial artery. The filament central venule in the central part of the filament merged into the venous plexus. Nutritive capillaries branched from efferent branchial arteries also drained toward the venous plexus. Such general vascular architecture is simpler than that of the fish. During metamorphosis, the pattern of the vascular distribution, especially filament net capillaries became irregular, and then markedly tortuous or convoluted blood vessels occurred in the absorbing gill. At the metamorphic climax, the capillary network practically disappeared in the remnant of the gill but the bypass shunt as a non-respiratory artery remained almost unchanged.

  9. Electron microscope and x-ray diffraction studies of the effects of dehydrations on the structure of nerve myelin. I. Peripheral nerve.

    PubMed

    FINEAN, J B

    1960-09-01

    The dehydration of frog sciatic nerve has been studied by allowing specimens to become partially or fully dried before fixation and preparation for electron microscopy. Low magnification electron micrographs of OsO(4)-fixed preparations showed marked tissue shrinkage which could be correlated quantitatively with the loss of water during the preliminary drying. KMnO(4)-fixation appeared to cause a rehydration of the dried tissue. Higher magnification electron micrographs of the OsO(4)-fixed preparations showed a sequence of modifications of the myelin layers which could be correlated with changes in the small-angle x-ray diffraction data which were recorded during drying. An intermediate stage of drying was characterised by a partial collapse of layers and a disappearance of the intraperiod dense line in some regions of the myelin sheath. Continuity between collapsed and non-collapsed layers was maintained throughout the sheath. The fully dried preparation showed two main modifications of the myelin layers. In many regions the layers (principal layers) resembled those of normal preparations, but showed an intensification and frequently a doubling of the intraperiod dense line. In addition, there was a very extensive system of fine (40 A periodicity) dense layers, some of which could be demonstrated to be continuous with the principal layers. In such cases it was observed that two of the fine layers were related to each principal layer. The correlation between diffraction data and electron microscope data is discussed, and some speculations are made concerning the molecular significance of the observations.

  10. X-ray diffraction and electron microscope study of phase separation in rod outer segment photoreceptor membrane multilayers.

    PubMed Central

    Gruner, S M; Rothschild, K J; Clark, N A

    1982-01-01

    Phase separation in artificially stacked multilayers of isolated bovine retinal rod outer segment (ROS) membranes has been examined via x-ray diffraction and electron microscopy. Specimens were prepared by isopotential spin drying followed with partial hydration by equilibration against moist gas streams. Upon dehydration, the multilamellar membrane phase assumes a binary phase composition consisting of concentrated protein-containing lamellae interspersed with microdomains of hexagonally packed tubes of lipid in a HII configuration. The HII lattice is geometrically coupled to the lamellar phase with one set of hexagonal crystal planes co-planar to the local membrane lamellae. The hexagonal microdomains bear a striking resemblance to the "paracrystalline inclusions" observed in fast-frozen, intact frog ROS (Corless and Costello. 1981. Exp. Eye Res. 32:217). The lamellar lattice is characterized by an unusually small degree of disorder. Sharp lamellar diffraction with a 120 A unit cell is observed (at near total dehydration) to a resolution of 6 A. A model consistent with the data is that a multilamellar array of ROS disks is stable as long as the external disk surfaces are kept sufficiently far apart. If the distance between the membranes is allowed to shrink below a certain critical value, the disk lipids spontaneously convert to a nonbilayer phase. This suggests that the structure of the ROS is stabilized by an internal framework that acts to keep the disks apart from one another and from the plasmalemma. Thus, the necessity of avoiding phase separations may provide a rationale for the peculiar morphology of the ROS. Images FIGURE 1 FIGURE 2 FIGURE 5 FIGURE 7 PMID:7139024

  11. Effect of different aspirin doses on arterial thrombosis after canine carotid endarterectomy: a scanning electron microscope and indium-111-labeled platelet study

    SciTech Connect

    Ercius, M.S.; Chandler, W.F.; Ford, J.W.; Swanson, D.P.; Burke, J.C.

    1984-02-01

    Although it is widely accepted that aspirin inhibits platelet aggregation in arterial thrombosis, the appropriate dosage of aspirin remains quite controversial. The purpose of this study was to determine the effect of different doses of aspirin (0.5 mg/kg vs. 10 mg/kg) on mural thrombus formation after carotid endarterectomy. Eighteen hours after oral aspirin administration, 20 endarterectomies were performed on mongrel dogs with the use of the operating microscope. Blood flow was then restored for 3 hours and the vessels were prepared for investigation with the scanning electron microscope. Ten endarterectomies were also performed on unmedicated dogs as controls. Five minutes before vessel unclamping, autologous indium-111-labeled platelets were administered intravenously, and the endarterectomized portions of the vessels were studied with a gamma counter system after harvesting. Group 1, the control group, revealed extensive mural thrombus consisting of platelet aggregates, fibrin, red blood cells, and white blood cells. Six of the 10 vessels in Group 2, premedicated with 0.5 mg of aspirin per kg, demonstrated varying amounts of mural thrombus. Group 3 (10 vessels), premedicated with 10 mg of aspirin per kg, revealed a platelet monolayer completely covering the exposed vessel wall media, with scattered white blood cells and infrequent fine fibrin strands overlying the platelet surface. The mean (+/- SD) radioactivity per group expressed as counts/minute/mm2 was: Group 1--2055.3 +/- 1905.5, log . 7.253 +/- 0.926; Group 2--1235.6 +/- 1234.3, log . 6.785 +/- 0.817; Group 3--526 +/- 433.06, log . 5.989 +/- 0.774.

  12. Electronic structure of individual hybrid colloid particles studied by near-edge X-ray absorption fine structure (NEXAFS) spectroscopy in the X-ray microscope.

    PubMed

    Henzler, Katja; Guttmann, Peter; Lu, Yan; Polzer, Frank; Schneider, Gerd; Ballauff, Matthias

    2013-02-13

    The electronic structure of individual hybrid particles was studied by nanoscale near-edge X-ray absorption spectromicroscopy. The colloidal particles consist of a solid polystyrene core and a cross-linked poly-N-(isopropylacrylamide) shell with embedded crystalline titanium dioxide (TiO(2)) nanoparticles (d = 6 ± 3 nm). The TiO(2) particles are generated in the carrier network by a sol-gel process at room temperature. The hybrid particles were imaged with photon energy steps of 0.1 eV in their hydrated environment with a cryo transmission X-ray microscope (TXM) at the Ti L(2,3)-edge. By analyzing the image stacks, the obtained near-edge X-ray absorption fine structure (NEXAFS) spectra of our individual hybrid particles show clearly that our synthesis generates TiO(2) in the anastase phase. Additionally, our spectromicroscopy method permits the determination of the density distribution of TiO(2) in single carrier particles. Therefore, NEXAFS spectroscopy combined with TXM presents a unique method to get in-depth insight into the electronic structure of hybrid materials. PMID:23360082

  13. Three-dimensional imaging of copper pillars using x-ray tomography within a scanning electron microscope: A simulation study based on synchrotron data

    SciTech Connect

    Martin, N.; Bertheau, J.; Charbonnier, J.; Hugonnard, P.; Lorut, F.; Bleuet, P.; Tabary, J.; Laloum, D.

    2013-02-15

    While microelectronic devices are frequently characterized with surface-sensitive techniques having nanometer resolution, interconnections used in 3D integration require 3D imaging with high penetration depth and deep sub-micrometer spatial resolution. X-ray tomography is well adapted to this situation. In this context, the purpose of this study is to assess a versatile and turn-key tomographic system allowing for 3D x-ray nanotomography of copper pillars. The tomography tool uses the thin electron beam of a scanning electron microscope (SEM) to provoke x-ray emission from specific metallic targets. Then, radiographs are recorded while the sample rotates in a conventional cone beam tomography scheme that ends up with 3D reconstructions of the pillar. Starting from copper pillars data, collected at the European Synchrotron Radiation Facility, we build a 3D numerical model of a copper pillar, paying particular attention to intermetallics. This model is then used to simulate physical radiographs of the pillar using the geometry of the SEM-hosted x-ray tomography system. Eventually, data are reconstructed and it is shown that the system makes it possible the quantification of 3D intermetallics volume in copper pillars. The paper also includes a prospective discussion about resolution issues.

  14. Light- and electron-microscopic histochemistry of Fabry's disease.

    PubMed Central

    Faraggiana, T.; Churg, J.; Grishman, E.; Strauss, L.; Prado, A.; Bishop, D. F.; Schuchman, E.; Desnick, R. J.

    1981-01-01

    A histochemical study was performed on light- and electron-microscopic level in a case of Fabry's disease. The patient underwent kidney transplantation for renal failure and died of heart failure 6 months later. Patient's tissues were studied at the light- and electron-microscopic levels with various embedding and staining techniques for lipids and carbohydrates. Two peroxidase-labeled lectins (from Ricinus communis and from Bandeiraea simplicifolia) known to have affinity for alpha- and beta-D-galactose, were strongly reactive with the storage material on frozen sections. The ultrahistochemical and extraction tests showed that the typical granules had a variable reactivity and morphologic characteristics in different cells, probably reflecting different composition. A small number of typical deposits were also observed in the transplanted kidney. This is the first reported case of recurrence of the storage disease in the allograft. Of interest was also the fact that the patient's blood inhibited normal alpha-galactosidase activity, suggesting a possible inhibitor-related mechanism in the pathogenesis of the recurrence. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 PMID:6786101

  15. [Undifferentiated carcinoma with lymphoid stroma (undifferentiated carcinoma nasopharyngeal type?). Optical, electron microscopical and immunofluorescence study (author's transl)].

    PubMed

    Wassef, M; Le Charpentier, Y; Monteil, J P; Le Tien, K; Galian, A

    1982-01-01

    A case of undifferentiated carcinoma with lymphoid stroma of the paired gland is reported in a chinese woman with positive Epstein-Barr virus serology. The histologic appearance of the tumor is very similar to undifferentiated carcinomas nasopharyngeal type (UCNT). Ultrastructural study reveals features of epidermoid differentiation. Immunofluorescence study shows numerous and predominant IgA plasma cells in the stroma. The relationship between this tumor and the benign lymphoepithelial lesions of the salivary glands are discussed. The present case and the review of the literature emphasize the morphological and epidemiological similarities between UCNT and undifferentiated carcinoma with lymphoid stroma of the salivary glands.

  16. Immunocytochemical localization of glial fibrillary acidic protein (GFAP) in the area postrema of the cat - Light and electron microscopic study

    NASA Technical Reports Server (NTRS)

    Damelio, F. E.; Gibbs, M. A.; Mehler, W. R.; Eng, L. F.

    1985-01-01

    Glial fibrillary acidic protein (GFAP) was demonstrated in the cytoplasm and processes of ependymal cells and astroglial components of the area postrema of the cat. These observations differ from the findings in the ependyma of the ventricular cavities which are consistently negative for the protein. Since some studies have suggested sensory functions of the glial cells in this emetic chemoreceptor trigger zone, a careful consideration of morphological and biochemical attributes of these cells seems appropriate.

  17. Afferent projections to pharynx and soft palate motoneurons: a light and electron microscopical tracing study in the cat.

    PubMed

    Boers, Jose; Hulshoff, Antoinette C; de Weerd, Henk; Mouton, Leonora J; Kuipers, Rutger; Holstege, Gert

    2005-05-23

    Pharynx and soft palate are muscles for respiration, vocalization, swallowing, and vomiting. In cat, motoneurons innervating pharynx/soft palate are located in the dorsal group of the nucleus ambiguus (dgNA) in the medulla oblongata. In cat, dgNA is the only part of nucleus ambiguus that can be distinguished as a separate cell group, which makes it possible to study its afferent input. In two cats, WGA-HRP injections in dgNA and surrounding tegmentum resulted in retrogradely labeled cells at several levels of the neuraxis. In 170 cases anterograde tracers were injected in areas in which the cells of origin were identified. Results demonstrate that dgNA afferents originate from the tegmentum dorsolateral to the superior olivary complex, medullary ventromedial tegmentum, caudal raphe nuclei, medullary lateral tegmental field, nucleus retroambiguus (NRA), and adjoining tegmentum, extending into the first cervical segment of the spinal cord. In order to determine whether periaqueductal gray (PAG) and parabrachial nuclei (PB) make synaptic contacts with dgNA, ultrastructural studies combined anterograde tracing from PAG, PB, and NRA with retrograde tracing of pharyngeal and soft palate motoneurons. The results showed that PB, but not PAG, projects to the dgNA and that NRA afferent synapses are three times as numerous as those from PB. The morphology of PB and NRA synapses is consistent with excitatory input. In conclusion, pharyngeal and soft palate motoneurons receive their afferents almost exclusively from the pontine and medullary tegmentum and first cervical spinal segment.

  18. Toxicological effects and recovery of the corneal epithelium in Cyprinus carpio communis Linn. exposed to monocrotophos: an scanning electron microscope study.

    PubMed

    Uppal, Ravneet Kaur; Johal, Mohinder Singh; Sharma, Madan Lal

    2015-05-01

    This study was conducted based on the evidence of fish habitats in North India being affected by organophosphate pesticides draining from agricultural fields into bodies of water, especially during the rainy season. Various tissues of fish such as scales, gills ovaries, kidney, and liver have been studied from the toxicological point of view, but the toxicological effects of aquatic pollutants on fish cornea have not been investigated to date. We conducted comparative toxicological studies on the cornea of Cyprinus carpio communis using two sublethal (0.038 and 0.126 ppm) concentrations of monocrotophos pesticide for 30 days. Corneas from all the groups were evaluated by a scanning electron microscope. The fish exposed to the monocrotophos pesticide developed corneal necrosis due to the formation of crystalloid-like structures, thinning and shrinkage of microridges on the corneal epithelium. After 30 days, fish from the monocrotophos-treated tank were transferred to normal environmental conditions. After 60 days under natural condition, epithelial cells did not fully recover. In conclusion, exposure to monocrotophos induces irreversible changes in the cornea of C. carpio communis. As fish and mammalian visual systems share many similarities, the reported finding may offer useful insights for further toxicological and ophthalmological studies in humans.

  19. Subclinical lumbar polyradiculopathy in aged domestic, laboratory, and exotic mammalian species--a light and selected electron microscopic study.

    PubMed

    Anderson, W I; Cummings, J F; Steinberg, H; de Lahunta, A; King, J M

    1989-10-01

    Lumbar polyradiculopathy, characterized by ballooning myelin sheaths and axonal distortion, was documented in multiple, aged, domestic, laboratory, and exotic mammalian species. Animals studied that exhibited this nerve rootlet change included the goat, sheep, pig, white-tailed deer, gerbil, vole, ferret, beaver, hedgehog, chinchilla, North Chinese leopard, lion, cheetah, mountain lion, llama, East African eland, Uganda giraffe, polar bear, and drill. Ultrastructurally, lumbar nerve rootlets from the North Chinese leopard revealed prominent and often multiple lamellar separations in the area of myelin bubbling. Clefts in myelin sheaths contained macrophages with engulfed fragments of myelin. Axons were sometimes variously attenuated, and the axoplasm contained densely packed neurofilaments. In all species, the lesion was subclinical and considered an incidental age-related finding. PMID:2766747

  20. [An electron microscopic study of the macro- and microcysts of coccidia in the genus Sarcocystis from buffalo].

    PubMed

    Gaibova, G D; Radchenko, A I

    1990-01-01

    Two sarcosporidian species from muscles of the water buffalo examined in Azerbaijan were studied. The one making macrocysts was identified as S. fusiformis, whereas the other producing microcysts appeared to be not S. levinei as it might have been expected. Indeed, the microcysts found in the muscles of the buffalo in the slaughterhouse [correction of slaughtery] of Baku differed essentially in morphology of the cyst wall from that of S. levinei, sooner resembling that of S. cruzi from cattle. The cyst wall of these microcysts was seen to make deep invaginations towards the ground substance of cysts. From these invaginations some curved channels were grown outlined with a filamentous material. The described pattern of cyst wall is not characteristic of the S. cruzi sarcocyst. No specification was achieved, and the sarcocysts found in the bubaline muscles are designated as Sarcocystis sp. from the buffalo.

  1. A polarized light and scanning electron microscopic study of human fissure and lingual enamel of unerupted mandibular third molars.

    PubMed

    Ekstrand, K; Holmen, L; Qvortrup, K

    1999-01-01

    Using histological and ultrastructural techniques the aims of this study were to investigate whether the mineralization pattern and surface microanatomy of the caries-susceptible fissure enamel were different from those on the caries-inactive lingual surface. The material consisted of 31 unerupted third mandibular molars. The specimens were initially grouped into four categories: (1) without, (2) with initial, (3) with almost completed and (4) with completed root formation. One ground section with fissure-like morphology was selected from each tooth. Using water as a medium the observed birefringence was negative along the lingual and fissure transverses in specimens with almost completed and with completed root formation, while the observed birefringence was positive at different distances in the enamel in sections representing less maturation stages. Qualitative imbibition studies revealed hypomineralized enamel in the lower part of the fissures in specimens representing almost and completed root formation. Imbibed in quinoline, parts of the hypomineralized enamel behaved like a molecular sieve due to the presence of micropores, indicating that the structural arrangement is different from that in the enamel adjacent to this areas. After division of the sections into a lingual and a buccal part, SEM features were described from lower and upper parts of the buccal fissure wall and on lingual enamel in the area corresponding to the bottom part of the fissure. The surface microanatomy varied greatly. Negative developmental irregularities such as fissures and holes were associated with the immature enamel, while matured enamel - particularly fissures - housed many positive developmental irregularities such as enamel caps and protrusions. The crystal size in the mature specimens appeared smaller and more uniform than the crystals from the immature specimens. Apart from the occurrence of hypomineralized enamel in fissures and numerous positive developmental

  2. A scanning electron microscopic study of in vitro toxicity of ethylene-oxide-sterilized bone repair materials.

    PubMed

    Zislis, T; Martin, S A; Cerbas, E; Heath, J R; Mansfield, J L; Hollinger, J O

    1989-01-01

    Polylactic acid (PLA) and polyglycolic acid (PGA) have been under investigation for use in the management of hard- and soft-tissue wounds. Current research has included the incorporation of osteo-inductive substances into a PLA-PGA copolymer alloplastic implant material for enhancement of the healing of osseous defects. Conventional methods of sterilization--such as dry heat, steam heat, or 60Co--tend either to destroy or attenuate osteo-inductive activity and alter polymer biodegradation. Ethylene oxide (EO) gas sterilization is currently being tested as an alternate method. This study examined the relationship of EO-induced cytotoxicity to the length of time of polymer aeration following EO sterilization. Three groups of copolymer implant discs were studied: (1) 50:50 PLA-PGA copolymer, (2) PLA-PGA polymer with hydroxyapatite (HA), and (3) PLA-PGA with autolyzed, antigen-extracted (AA) bone particles. Polymer discs, as well as particulate HA and AA bone controls, were sterilized with EO for 12 hours. Following periods of two weeks, one week, one day, or no subsequent vacuum aeration, samples were placed into 24-well culture plates. A suspension of human fibroblasts was added to each well. Cell growth and attachment were permitted for 24 hours. Medium was then removed, and solutions for cell fixation, buffer washing, and dehydration were added to each well. SEM examination revealed changes in cell growth with increasing periods of aeration suggestive of increasing cell vitality. Cells growing on discs having no aeration were small, round, and lobulated, whereas those of seven to 14 days' aeration were more numerous, and flattened with many microvilli, pseudopodia, and dendritic processes, features consistent with normal cell morphology. These results suggest that EO-sterilized polymer implants should be aerated for least seven to 14 days prior to surgical use. PMID:2561372

  3. Integration of a high-NA light microscope in a scanning electron microscope.

    PubMed

    Zonnevylle, A C; Van Tol, R F C; Liv, N; Narvaez, A C; Effting, A P J; Kruit, P; Hoogenboom, J P

    2013-10-01

    We present an integrated light-electron microscope in which an inverted high-NA objective lens is positioned inside a scanning electron microscope (SEM). The SEM objective lens and the light objective lens have a common axis and focal plane, allowing high-resolution optical microscopy and scanning electron microscopy on the same area of a sample simultaneously. Components for light illumination and detection can be mounted outside the vacuum, enabling flexibility in the construction of the light microscope. The light objective lens can be positioned underneath the SEM objective lens during operation for sub-10 μm alignment of the fields of view of the light and electron microscopes. We demonstrate in situ epifluorescence microscopy in the SEM with a numerical aperture of 1.4 using vacuum-compatible immersion oil. For a 40-nm-diameter fluorescent polymer nanoparticle, an intensity profile with a FWHM of 380 nm is measured whereas the SEM performance is uncompromised. The integrated instrument may offer new possibilities for correlative light and electron microscopy in the life sciences as well as in physics and chemistry.

  4. A scanning electron microscopic study on the distribution of peritubular dentine in cheek teeth of Cervidae and Suidae (Mammalia, Artiodactyla).

    PubMed

    Kierdorf, H; Kierdorf, U

    1992-09-01

    Distribution of peritubular dentine was studied in cheek teeth of fallow deer (Dama dama), roe deer (Capreolus capreolus) and wild boar (Sus scrofa). In the two cervid species, especially intense peritubular dentine formation was found in the outer regions of mid and cuspal coronal dentine. In these areas a marked asymmetry occurred, peritubular dentine being predominantly secreted onto the side of the dentinal tubule walls nearest to the dentinoenamel junction. Intensity and asymmetry of peritubular dentine formation decreased cervically. In root dentine, the walls of the dentinal tubules were covered with only a thin peritubular dentine layer of even thickness. Here, in contrast to peripheral coronal dentine, the volume of intertubular dentine far exceeded that of peritubular dentine. In porcine coronal dentine, PTD asymmetry, being of lesser extent than in cervids, was observed only in peripheral areas of cuspal and flank regions of the cheek teeth. Because peritubular is more highly mineralized than intertubular dentine, the relative volume of dentine made up from the two components has an important influence on dentinal wear resistance. The significance of variations in volume and distribution of peritubular dentine between different dentinal regions for achieving and maintaining a functional occlusal surface is shown for cervid cheek teeth. Our results suggest that dentinal structure (in addition to enamel structure) should be taken more into consideration when discussing occlusal surface morphology in herbi- and omnivores from a functional point of view.

  5. Premartensitic microstructures as seen in the high-resolution electron microscope: A study of a Ni-Al alloy

    SciTech Connect

    Schryvers, D.; Tanner, L.; Van Tendeloo, G.

    1988-02-12

    The present study indicates that the B2 ..beta..-phase in quenched Ni/sub 62.5/Al/sub 37.5/ is distorted by displacement waves involving a planar shufflin of atoms resembling the final 7R martensite structure and with wavelenghts of the order of 1.3 nm. The appearance of a <110><110> type modulation with the indicated periodicity corresponds well with recent inelastic neutron scattering results which reveal nonlinear behavior in the TA<110> phonon dispersion curve around the same wavelengths indicating a partial lattice softening for such waves. In bulk material all six equivalent wave-vectors are equally present. These distortional modulations are configured in some form of three-dimensional assembly. Following the interpretation given above, it can be concluded that a one-dimensional domain structure along one of six <110> directions may exist. However, the beating of six displacement waves with apparently uncorrelated phase and wavelengths rules out the existence of a ''conventional'' three-dimensional domain structure. For this reason it is uncertain whether much more information can be gained from such image simulations. There are now numerous indications that the underlying structure to the tweed contrast in this alloy is a precursor effect of the martensitic transformation. However, a detailed description of the effective correlation between the distorted parent phase and the martensitic product phase has yet to be developed. Recent HREM results reveal the existence of a sequence of different structures in the transition region between the modulated ..beta..-phase and the martensitic phase, depending on parameters such as the local composition and stress. Such transition structures include modulated k..beta..-phase in which only one (110) modulation is preferred or in which the periodicity differs from the above described 1.3 nm and the FCT L1/sub o/ martensite with single shear defects. 1 fig., 26 refs.

  6. Solar cell evaluation using electron beam induced current with the large chamber scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Wink, Tara; Kintzel, Edward; Marienhoff, Peter; Klein, Martin

    2012-02-01

    An initial study using electron beam induced current (EBIC) to evaluate solar cells has been carried out with the large chamber scanning electron microscope (LC-SEM) at the Western Kentucky University Nondestructive Analysis Center. EBIC is a scanning electron microscope technique used for the characterization of semiconductors. To facilitate our studies, we developed a Solar Amplification System (SASY) for analyzing current distribution and defects within a solar cell module. Preliminary qualitative results will be shown for a solar cell module that demonstrates the viability of the technique using the LC-SEM. Quantitative EBIC experiments will be carried out to analyze defects and minority carrier properties. Additionally, a well-focused spot of light from an LED mounted at the side of the SEM column will scan the same area of the solar cell using the LC-SEM positioning system. SASY will then output the solar efficiency to be compared with the minority carrier properties found using EBIC.

  7. Study on surface magnetic domain structure of thin-gauged 3%Si-Fe strips using scanning electron microscope with polarization analyzer

    SciTech Connect

    Lee, Y.; Koymen, A.R.; Heo, N.H.; Na, J.G.; Woo, J.S.

    1998-04-03

    Due to the important soft magnetic characteristics, 3%Si-Fe strips have been extensively studied and is currently used as core material of distribution and power transformers where energy losses during magnetization are of critical concern. It is well known that the energy loss decreases significantly with decreasing thickness of 3%Si-Fe strips. (110)[001] Goss texture in thin-gauged 3%Si-Fe strips is developed through a tertiary recrystallization process which is induced by the difference in surface energy of (110) and other grains. To reduce the energy losses of 3%Si-Fe strips, the domain modification by the application of uniaxial tensile stress, mechanical scribing and laser scribing has been developed, but there are few studies on the domain structure of the thin-gauged Si-Fe strips. In this study, the magnetic property, B{sub 10}(T), is controlled by changing the reduction ratio per pass are (hereafter, reduction rate) in cold rolling 3%Si-Fe plates, and surface magnetic domain structures each are imaged using scanning electron microscope with polarization analyzer (SEMPA).

  8. Effects of pulsed Er:YSGG and Ho:YAG laser on the organ of Corti of the guinea pig cochlea: a scanning electron microscopic study

    NASA Astrophysics Data System (ADS)

    Jamali, Yasmin; Jovanovic, Sergije; Schoenfeld, Uwe; Anft, D.; Ertl, Thomas P.; Scherer, Hans H.; Berghaus, A.; Mueller, Gerhard J.

    1998-01-01

    Laser stapedotomy has now become an established method in the surgical treatment of otosclerosis. Recent experimental studies have demonstrated that, apart from the continuous wave lasers, several pulsed laser systems are also suitable for stapes management. Experiments were performed in guinea pigs to clarify which, if any, of the pulsed lasers used can damage the inner ear on application of the laser parameters required for the stapedotomy. The basal convolution of the guinea-pig cochlea was chosen as the application site. Acoustic evoked potentials (compound action potentials) yielded information on inner-ear function. With the Er:YSGG laser (energy: 85 J/pulse, energy density: 36 J/cm2, total energy: 0.425 J), five applications to the cochlea are necessary for a foot plate perforation of 500 - 600 micrometers . With the Ho:YAG laser, an adequately large perforation can be achieved with at least 10 applications of an energy of 210 mJ per pulse (energy density: 90 J/cm2, total energy: 2.1 J). The aim of this study was: (1) to clarify whether the Er:YSGG and Ho:YAG laser could cause morphological changes in the organ of Corti of the guinea pig on application of the laser parameters required for stapedotomy, and (2) to verify our experimental electrophysiological results and correlate them with the morphological changes detected in the organ of Corti in the guinea pig cochlea by scanning-electron-microscopic examination. It shows that the effective laser parameters (5 X 85 mJ) of the Er:YSGG-laser cause no changes of the guinea pig cochlea. Even with the application of 25 pulses with the same energy the guinea pig cochlea shows normal appearance. The effective laser parameters of the Ho:YAG laser (10 X 210 mJ) show changes in the outer hair cells in the form of stereocilie fusion and giant hair cell formation while the inner hair cells and supporting cells are showing normal appearance. Our results clearly demonstrate a high application safety for the Er:YSGG laser

  9. Fully Mechanically Controlled Automated Electron Microscopic Tomography

    PubMed Central

    Liu, Jinxin; Li, Hongchang; Zhang, Lei; Rames, Matthew; Zhang, Meng; Yu, Yadong; Peng, Bo; Celis, César Díaz; Xu, April; Zou, Qin; Yang, Xu; Chen, Xuefeng; Ren, Gang

    2016-01-01

    Knowledge of three-dimensional (3D) structures of each individual particles of asymmetric and flexible proteins is essential in understanding those proteins’ functions; but their structures are difficult to determine. Electron tomography (ET) provides a tool for imaging a single and unique biological object from a series of tilted angles, but it is challenging to image a single protein for three-dimensional (3D) reconstruction due to the imperfect mechanical control capability of the specimen goniometer under both a medium to high magnification (approximately 50,000–160,000×) and an optimized beam coherence condition. Here, we report a fully mechanical control method for automating ET data acquisition without using beam tilt/shift processes. This method could reduce the accumulation of beam tilt/shift that used to compensate the error from the mechanical control, but downgraded the beam coherence. Our method was developed by minimizing the error of the target object center during the tilting process through a closed-loop proportional-integral (PI) control algorithm. The validations by both negative staining (NS) and cryo-electron microscopy (cryo-EM) suggest that this method has a comparable capability to other ET methods in tracking target proteins while maintaining optimized beam coherence conditions for imaging. PMID:27403922

  10. Fully Mechanically Controlled Automated Electron Microscopic Tomography

    NASA Astrophysics Data System (ADS)

    Liu, Jinxin; Li, Hongchang; Zhang, Lei; Rames, Matthew; Zhang, Meng; Yu, Yadong; Peng, Bo; Celis, César Díaz; Xu, April; Zou, Qin; Yang, Xu; Chen, Xuefeng; Ren, Gang

    2016-07-01

    Knowledge of three-dimensional (3D) structures of each individual particles of asymmetric and flexible proteins is essential in understanding those proteins’ functions; but their structures are difficult to determine. Electron tomography (ET) provides a tool for imaging a single and unique biological object from a series of tilted angles, but it is challenging to image a single protein for three-dimensional (3D) reconstruction due to the imperfect mechanical control capability of the specimen goniometer under both a medium to high magnification (approximately 50,000–160,000×) and an optimized beam coherence condition. Here, we report a fully mechanical control method for automating ET data acquisition without using beam tilt/shift processes. This method could reduce the accumulation of beam tilt/shift that used to compensate the error from the mechanical control, but downgraded the beam coherence. Our method was developed by minimizing the error of the target object center during the tilting process through a closed-loop proportional-integral (PI) control algorithm. The validations by both negative staining (NS) and cryo-electron microscopy (cryo-EM) suggest that this method has a comparable capability to other ET methods in tracking target proteins while maintaining optimized beam coherence conditions for imaging.

  11. Electron Microscopic Observations of Rabbit Antibodies.

    PubMed

    Hall, C E; Nisonoff, A; Slayter, H S

    1959-12-01

    Electron micrographs were obtained showing the individual, shadow-cast macromolecules from solutions of purified anti-p-azobenzoate rabbit antibody and of normal gamma-globulin. The two materials look alike and consist mainly of asymmetrical rod-like particles about 30 to 40 A in diameter. Lengths are not constant but the weight average is about 250 A for the antibodies and about 200 A for the gamma-globulin. The average observed dimensions are reasonably consistent with values deduced from physical-chemical methods, although the shape is more nearly that of a cylindrical rod rather than the ellipsoid employed in hydrodynamical theory. Mixtures of antibody and specific dihaptenic dye were examined in attempts to establish the mode of the specific aggregation. At the high dilutions necessary for electron microscopy (0.1 mg./ml.), the effect of the dye was small and tended to be masked by non-specific aggregation on drying. The evidence suggests that under these conditions the specific reaction involves an end-to-end aggregation of the elementary particles to produce a weight average length about twice that of the pure antibody.

  12. Fully Mechanically Controlled Automated Electron Microscopic Tomography.

    PubMed

    Liu, Jinxin; Li, Hongchang; Zhang, Lei; Rames, Matthew; Zhang, Meng; Yu, Yadong; Peng, Bo; Celis, César Díaz; Xu, April; Zou, Qin; Yang, Xu; Chen, Xuefeng; Ren, Gang

    2016-01-01

    Knowledge of three-dimensional (3D) structures of each individual particles of asymmetric and flexible proteins is essential in understanding those proteins' functions; but their structures are difficult to determine. Electron tomography (ET) provides a tool for imaging a single and unique biological object from a series of tilted angles, but it is challenging to image a single protein for three-dimensional (3D) reconstruction due to the imperfect mechanical control capability of the specimen goniometer under both a medium to high magnification (approximately 50,000-160,000×) and an optimized beam coherence condition. Here, we report a fully mechanical control method for automating ET data acquisition without using beam tilt/shift processes. This method could reduce the accumulation of beam tilt/shift that used to compensate the error from the mechanical control, but downgraded the beam coherence. Our method was developed by minimizing the error of the target object center during the tilting process through a closed-loop proportional-integral (PI) control algorithm. The validations by both negative staining (NS) and cryo-electron microscopy (cryo-EM) suggest that this method has a comparable capability to other ET methods in tracking target proteins while maintaining optimized beam coherence conditions for imaging. PMID:27403922

  13. Nature Study with the Microscope.

    ERIC Educational Resources Information Center

    Sollberger, Dwight E.

    1991-01-01

    Identifies specific instruction difficulties, potential problems, solutions, and activities for successful use of microscopes in the classroom. Procedures are outlined for guiding students in creating their own slides with monocotyledon and dicotyledon stems, fern spores, stomata, lichens, and red onions. (MCO)

  14. Microvasculature of the retina, ciliary processes and choroid in the North American raccoon (Procyon lotor) eye: a scanning electron microscopic study of corrosion casts.

    PubMed

    Ninomiya, Hiroyoshi; Inomata, Tomo; Kanemaki, Nobuyuki

    2005-06-01

    We have studied the vasculature of the retina, ciliary processes and choroid in the North American raccoon (Procyon lotor), a nocturnal mammal, using light and scanning electron microscopic examination of corrosion casts. We carried out an identical study in the crab-eating macaque (Macaca fascicularis), which forages only during the daytime, in order to compare the ocular vasculature with that of nocturnal mammals. Our observations in raccoons demonstrated a photoreceptor layer associated with rich lymph and a poorly vascularized retina. The meridian region of the eye, which lies in the horizontal plane and pass around the optic disc, had a markedly sparse capillary network. This horizontal sparse vascular band may correspond to a visual streak. Ciliary process capillaries were delicate, and formed a well-developed and compact network. Choriocapillaries were quite thin and formed a coarse capillary network. This contrasted with the dense retinal and well-extended choroidal capillary networks noted in the macaques. Our findings suggest that the sparse retinal capillary network in raccoons is extremely beneficial for photon capture, thereby allowing the raccoon to see well at night, as the retinal vessels restrict the inflow of photons toward the photoreceptors. The well-developed lymph probably compensates for the sparse retinal capillaries and choriocapillaries and nourishes the retina in the nocturnal raccoon.

  15. Electron microscopic observation of preretinal membranes.

    PubMed

    Yamamoto, T; Yamashita, H; Hori, S

    1989-01-01

    In this report, membranes removed during vitrectomy were observed by various methods of electron microscopy to determine their three-dimensional structure and the mechanism of the contraction of preretinal membranes. The vitreous side surface of the preretinal membranes was covered by two types of flat cells, cells with long, extended processes and cells in a pavement arrangement. The lamellae of the flat cells in the internal structures of the preretinal membranes were also observed. In each lamella, the cells appeared to have a connection with each other and formed networks. The retinal side surface of the preretinal membranes was smooth and acellular. The glycerinated preretinal membranes were exposed to ATP and Mg2+, which induced the contraction of the component cells of the preretinal membranes. When the cells on the vitreous side surface of the preretinal membranes contracted, the intercellular connections among them appeared to be preserved.

  16. Colocalization of gamma-aminobutyric acid and acetylcholine in neurons in the laterodorsal and pedunculopontine tegmental nuclei in the cat: a light and electron microscopic study.

    PubMed

    Jia, Hong-Ge; Yamuy, Jack; Sampogna, Sharon; Morales, Francisco R; Chase, Michael H

    2003-12-01

    Cholinergic and gamma-aminobutyric acid (GABA) mechanisms in the dorsolateral pontomesencephalic tegmentum have been implicated in the control of active (REM) sleep and wakefulness. To determine the relationships between neurons that contain these neurotransmitters in this region of the brainstem in adult cats, combined light and electron microscopic immunocytochemical procedures were employed. Light microscopic analyses revealed that choline acetyltransferase (ChAT) and GABA immunoreactive neurons were distributed throughout the laterodorsal and pedunculopontine tegmental nuclei (LDT and PPT). Surprisingly, approximately 50% of the ChAT immunoreactive neurons in these nuclei also contained GABA. Using electron microscopic pre-embedding immunocytochemistry, GABA immunoreactivity was observed in somas, dendrites and axon terminals in both the LDT and PPT. Most of the GABA immunoreactive terminals formed symmetrical synapses with non-immunolabeled dendrites. Electron microscopic double-immunolabeling techniques revealed that ChAT and GABA were colocalized in axon terminals in the LDT/PPT. Approximately 30% of the ChAT immunoreactive terminals were also GABA immunoreactive, whereas only 6-8% of the GABA immunoreactive terminals were ChAT immunoreactive. Most of the ChAT/GABA immunoreactive terminals formed symmetrical synapses with non-immunolabeled dendrites; however, ChAT/GABA immunoreactive terminals were also observed that contacted ChAT immunoreactive dendrites. With respect to ChAT immunoreactive postsynaptic profiles, approximately 40% of the somas and 50% of the dendrites received synaptic contact from GABA immunoreactive terminals in both the LDT and PPT. These findings (a) indicate that there are fundamental interactions between cholinergic and GABAergic neurons within the LDT/PPT that play an important role in the control of active sleep and wakefulness and (b) provide an anatomical basis for the intriguing possibility that a mechanism of acetylcholine and

  17. Microscopic theory of the residual surface resistivity of Rashba electrons

    NASA Astrophysics Data System (ADS)

    Bouaziz, Juba; Lounis, Samir; Blügel, Stefan; Ishida, Hiroshi

    2016-07-01

    A microscopic expression of the residual electrical resistivity tensor is derived in linear response theory for Rashba electrons scattering at a magnetic impurity with cylindrical or noncylindrical potential. The behavior of the longitudinal and transversal residual resistivity is obtained analytically and computed for an Fe impurity at the Au(111) surface. We studied the evolution of the resistivity tensor elements as a function of the Rashba spin-orbit strength and the magnetization direction of the impurity. We found that the absolute values of longitudinal resistivity reduce with increasing spin-orbit strength of the substrate and that the scattering of the conduction electrons at magnetic impurities with magnetic moments pointing in directions not perpendicular to the surface plane produce a planar Hall effect and an anisotropic magnetoresistance even if the impurity carries no spin-orbit interaction. Functional forms are provided describing the anisotropy of the planar Hall effect and the anisotropic magnetoresistance with respect to the direction of the impurity moment. In the limit of no spin-orbit interaction and a nonmagnetic impurity of cylindrical symmetry, the expression of the residual resistivity of a two-dimensional electron gas has the same simplicity and form as for the three-dimensional electron gas [J. Friedel, J. Nuovo. Cim. 7, 287 (1958), 10.1007/BF02751483] and can also be expressed in terms of scattering phase shifts.

  18. Smear layer removal efficacy of combination of herbal extracts in two different ratios either alone or supplemented with sonic agitation: An in vitro scanning electron microscope study

    PubMed Central

    Chhabra, Naveen; Gyanani, Hitesh; Kamatagi, Laxmikant

    2015-01-01

    Objectives: The study aimed to evaluate the effectiveness of the combination of two natural extracts in varying ratios for removal of smear layer either alone or supplemented with sonic agitation. Materials and Methods: Fifty extracted single-rooted teeth were collected, disinfected and decoronated below the cementoenamel junction to obtain standardized root length of 10 mm. Root canals were instrumented using rotary files at working length 1 mm short of the apex. Specimens were divided into six groups according to the irrigation protocol as follows: Group A – Distilled water, Group B – 17% ethylenediaminetetraacetic acid, Group C – Herbal extracts in 1:1 ratio, Group D – Herbal extracts in 1:1 ratio supplemented with sonic agitation, Group E – Herbal extracts in 2:1 ratio, Group F – Herbal extracts in 2:1 ratio supplemented with sonic agitation. Specimens were longitudinally sectioned and evaluated under scanning electron microscope for smear layer removal efficacy. Obtained scores were statistically analyzed using one-way analysis of variance and post-hoc test. Results: Among all, Group B showed the best results followed by Group F. Remaining other groups showed inferior outcome (P < 0.05). Conclusion: The combination of two extracts in 2:1 ratio was slightly better than 1:1 ratio and the smear layer removal efficacy was further improved when accompanied with sonic agitation. PMID:26430300

  19. Effect of advanced irrigation protocols on self-expanding Smart-Seal obturation system: A scanning electron microscopic push-out bond strength study

    PubMed Central

    Hegde, Vibha; Arora, Shashank

    2015-01-01

    Introduction: The aim of this study was to evaluate the effect of different final irrigation activation techniques affect the bond strength of self-expanding Smart-Seal obturation at the different thirds of root canal space. Materials and Methods: One hundred single-rooted human teeth were prepared using the Pro-Taper system to size F3, and a final irrigation regimen using 3% sodium hypochlorite and 17% EDTA was performed. The specimens were randomly divided into five groups (n = 20) according to the final irrigation activation technique used as follows: No activation (control), manual dynamic activation (MDA), CanalBrush activation, ultrasonic activation (UA) and EndoActivator. Five specimens from each group were subjected to scanning electron microscopic observation for assessment of the smear layer removal after the final irrigation procedures. All remaining roots were then obturated with Smart-Seal obturation system. A push-out test was used to measure the bond strength between the root canal dentin and Smart-Seal paste. The data obtained from the push-out test were analyzed using two-way analysis of variance and Tukey post-hoc tests. Conclusions: It was observed that UA improved the bond strength of Smart-Seal obturation in the coronal and middle third and MDA/EndoActivator in the apical third of the root canal space. PMID:25684907

  20. Structural and electron-microscopic studies of jacalin from jackfruit (Artocarpus integrifolia) show that this lectin is a 65 kDa tetramer.

    PubMed

    Ruffet, E; Paquet, N; Frutiger, S; Hughes, G J; Jaton, J C

    1992-08-15

    The 133-amino-acid sequences of the alpha-subunit of jacalin (a lectin from Artocarpus integrifolia) and of the slightly larger alpha'-subunit were determined. The alpha'- and alpha-subunits, in the approximate ratio of 1:3, were found to be virtually identical in their primary structures, except for one valine for isoleucine substitution at position 113. Although both alpha'- and alpha-chains were glycosylated, the extent of glycosylation in the alpha'-chain was much greater than that in the alpha-subunit. In the alpha'-polypeptide, all molecules contained an N-linked oligosaccharide at position 74 and some contained sugar at position 43. The alpha- and alpha'-subunits were found to be strongly non-covalently associated with three distinct beta-subunits containing 20 amino acids each. Electron-microscopic visualization of native jacalin disclosed a structure composed of four alpha-type subunits with a clear-cut 4-fold symmetry. Analytical-ultracentrifugation studies of jacalin revealed an average molecular mass of 65 kDa, a value compatible with a tetrameric structure of the alpha(alpha')-subunits. The recalculated number of sugar-binding sites per jacalin molecule, given a molecular mass of 65 kDa, would yield 0.8 sites per alpha(alpha')-promoter, i.e. about twice the value previously determined [Appukutan & Basu (1985) FEBS Lett. 180, 331-334; Ahmed & Chatterjee (1989) J. Biol. Chem. 264, 9365-9372].

  1. A high resolution study of the glycocalyx of rat uterine epithelial cells during early pregnancy with the field emission gun scanning electron microscope.

    PubMed

    Jones, B J; Murphy, C R

    1994-10-01

    The field emission gun scanning electron microscope has been used to investigate morphological changes at the macromolecular level in the glycocalyx of rat uterine luminal epithelial cells during early pregnancy. This very high resolution microscope has allowed visualisation at a level previously unobtainable and has enabled us to establish that dramatic alterations occur in this glycocalyx at the time of blastocyst attachment. On d 1 of pregnancy a prominent, filamentous glycocalyx radiates from the microvilli. However, by d 6 of pregnancy when the microvilli have been replaced by irregular cell surface protrusions, the glycocalyceal filaments are completely lost and the plasma membrane appears smooth and covered with a felt-like coating. These morphological observations suggest a major reorganisation in surface carbohydrates during early pregnancy and extend histochemical observations on the uterine epithelial glycocalyx.

  2. Understanding the formation and growth of Ag nanoparticles on silver chromate induced by electron irradiation in electron microscope: A combined experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Fabbro, Maria T.; Gracia, Lourdes; Silva, Gabriela S.; Santos, Luís P. S.; Andrés, Juan; Cordoncillo, Eloisa; Longo, E.

    2016-07-01

    Ag2CrO4 microcrystals were synthesized using the co-precipitation method. These microcrystals were characterized through X-ray diffraction (XRD) with Rietveld analysis, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) with energy-dispersive spectroscopy (EDS), micro-Raman (MR). XRD patterns and Rietveld refinement data showed that the material exhibits an orthorhombic structure without any deleterious phases. FE-SEM and TEM micrographs revealed the morphology and the growth of Ag nanoparticles on Ag2CrO4 microcrystals during electron beam irradiation. These events were directly monitored in real-time. Their optical properties were investigated using ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy that allowed the calculation of the optical band gap energy. Theoretical analyses based on the density functional theory level indicate that the incorporation of electrons is responsible for structural modifications and formation of defects on the [AgO6] and [AgO4] clusters, generating ideal conditions for the growth of Ag nanoparticles.

  3. Estimation of changes in nickel and chromium content in nickel-titanium and stainless steel orthodontic wires used during orthodontic treatment: An analytical and scanning electron microscopic study

    PubMed Central

    Kararia, Vandana; Jain, Pradeep; Chaudhary, Seema; Kararia, Nitin

    2015-01-01

    Introduction: The biocompatibility of orthodontic dental alloys has been investigated over the past 20 years, but the results have been inconclusive. The study compares standard 3 M Unitek nickel-titanium (NiTi) and stainless steel archwires with locally available JJ orthodontics wires. Scanning electron microscope (SEM) study of surface changes and complexometric titration to study compositional change was performed. Materials and Methods: Ten archwires each of group 1–3 M 0.016” NiTi, group 2-JJ 0.016” NiTi, group 3–3 M 0.019” *0.025” SS and group 4-JJ SS contributed a 10 mm piece of wire for analysis prior to insertion in the patient and 6 weeks post insertion. SEM images were recorded at ×2000, ×4000 and ×6000 magnification. The same samples were subjected to complexiometric titration using ethylenediaminetetraacetic acid to gauge the actual change in the composition. Observations and Results: The SEM images of all the archwires showed marked changes with deep scratches and grooves and dark pitting corrosion areas post intraoral use. 3M wires showed an uniform criss-cross pattern in as received wires indicating a coating which was absent after intraoral use. There was a significant release of Nickel and Chromium from both group 3 and 4. Group 2 wires released ions significantly more than group 1 (P = 0.0). Conclusion: Extensive and stringent trials are required before certifying any product to be used in Orthodontics. PMID:25684911

  4. Scanning electron microscope facility for examination of radioactive materials

    SciTech Connect

    Gibson, J.R.; Braski, D.N.

    1985-02-01

    An AMRAY model 1200B scanning electron microscope was modified to permit remote examination of radioactive specimens. Features of the modification include pneumatic vibration isolation of the column, motorized stage controls, improvements for monitoring vacuum, and a system for changing filaments without entering the hot cell.

  5. In situ nanoindentation in a transmission electron microscope

    SciTech Connect

    Minor, Andrew M.

    2002-12-02

    This dissertation presents the development of the novel mechanical testing technique of in situ nanoindentation in a transmission electron microscope (TEM). This technique makes it possible to simultaneously observe and quantify the mechanical behavior of nano-scale volumes of solids.

  6. High-resolution field emission scanning electron microscope imaging of internal cell structures after Epon extraction from sections: a new approach to correlative ultrastructural and immunocytochemical studies.

    PubMed

    Ris, H; Malecki, M

    1993-01-01

    The availability of high-resolution field emission scanning electron microscopes (FESEM) and the recent development of a less destructive method for extracting Epon from sections motivated us to investigate these techniques for the study of internal cell structures. We chose the nuclear pore complex (NPC) and insect striated muscle as test objects. Chemically fixed or rapidly cryoimmobilized samples were embedded in Epon 812. The Epon was extracted from 200- to 300-nm-thick sections with a modified potassium methoxide-crown ether complex. The samples were viewed with high-resolution FESEM at low voltages. In tangential sections of isolated nuclear envelopes from Xenopus oocytes the cytoplasmic and intranuclear components ("fishtraps") of NPCs appeared identical to what has been described from whole mounts. In cross sections, fishtraps are seen in side view, which is possible only with this technique. In longitudinal and cross sections of insect flight muscle the classical arrangement of myofilaments and cross-bridges is well preserved. This method now makes it possible to image internal cell structures from any desired angle by high-resolution FESEM. Immunolabeling studies on the rabbit psoas muscle demonstrated that antigenicity of alpha-actinin was retained in Epon-extracted sections. Immunogold labeling with antibodies against alpha-actinin conjugated to 3-nm gold beads was intense, highly specific, and restricted to the Z lines. This method can overcome the penetration problem of immunogold labeling, since any cell component can be positioned at the surface of the section. Obviously this approach can become a powerful new tool for many areas of structural cell biology. PMID:8130038

  7. Comparing the Marginal Adaptation of Cold Ceramic and Mineral Trioxide Aggregate by Means of Scanning Electron Microscope: An In vitro Study

    PubMed Central

    Mokhtari, Fatemeh; Modaresi, Jalil; Javadi, Gholamreza; Davoudi, Amin; Badrian, Hamid

    2015-01-01

    Background: Long-term success of endodontic surgeries is often influenced by the type of root-end filling material (RFM). The aim of present study was to compare the marginal adaptation of two different RFM, cold ceramic (CC) and mineral trioxide aggregate (MTA), using scanning electron microscope (SEM). Materials and Methods: About 20 extracted human single-rooted teeth were collected and stored into sodium hypochlorite 5.25%. The teeth were decronated from the cemento-enamel junction to prepare 16 mm roots. The working length was measured, and 1/3 coronal of the canal was prepared by Gates-Glidden drills. Apical flaring was followed by K file size # 40-70 based on step back technique. After filling of the canals, 3 mm above the apex was cut at 90° to the long axis. Furthermore, 3 mm of the filling was removed from the apical part using the ultrasonic device. All of the prepared specimens were divided into two groups and were retro filled by MTA and CC. The roots were cut horizontally from 1 mm above the apical part, and dentin-filling material interface was observed by SEM. Finally, the collected data were analyzed by Mann-Whitney test and using SPSS software version 18 at a significant level of 0.05. Results: The mean interfacial adaptation was higher in CC group. However, no significant differences were observed by statistical test (P = 0.35). Conclusion: Both CC and MTA had similar marginal adaptation as RFM however in vivo studies are recommended for better determination. PMID:26435608

  8. Response function and optimum configuration of semiconductor backscattered-electron detectors for scanning electron microscopes

    SciTech Connect

    Rau, E. I.; Orlikovskiy, N. A.; Ivanova, E. S.

    2012-06-15

    A new highly efficient design for semiconductor detectors of intermediate-energy electrons (1-50 keV) for application in scanning electron microscopes is proposed. Calculations of the response function of advanced detectors and control experiments show that the efficiency of the developed devices increases on average twofold, which is a significant positive factor in the operation of modern electron microscopes in the mode of low currents and at low primary electron energies.

  9. A combined apparatus of scanning reflection electron microscope and scanning tunneling microscope

    NASA Astrophysics Data System (ADS)

    Maruno, S.; Nakahara, H.; Fujita, S.; Watanabe, H.; Kusumi, Y.; Ichikawa, M.

    1997-01-01

    A scanning reflection electron microscope (SREM) combined with a scanning tunneling microscope (STM) has been developed for the purpose of nanoscale structure fabrication under ultrahigh vacuum conditions. A STM unit consists of a piezoelectric tube scanner and an inch runner for coarse and fine approach of a STM tip. A sample holder and the STM unit have six drive axes relative to an electron gun for simultaneous observation by SREM and STM. Energy-dispersive x-ray spectroscopy equipment is also installed for surface sensitive elemental analysis. It has been demonstrated that on a Si(111)7×7 surface atomic steps and 7×7 unit, cells can be observed in the SREM and STM images, respectively, and that surface elements with less than 1 ML thickness are detectable.

  10. Parabrachial innervation of the cat's dorsal lateral geniculate nucleus: an electron microscopic study using the tracer Phaseolus vulgaris leucoagglutinin (PHA-L).

    PubMed

    Cucchiaro, J B; Uhlrich, D J; Sherman, S M

    1988-12-01

    Ascending pathways from the brain stem play a key role, generally facilitatory, in controlling the transmission of retinal information through the lateral geniculate nucleus to the visual cortex (for reviews, see Singer, 1977; Burke and Cole, 1978; Sherman and Koch, 1986). In order to characterize the morphological basis of this brain-stem control, we used the electron microscope to study synaptic terminals labeled anterogradely from injections of the tracer Phaseolus vulgaris leucoagglutinin into the parabrachial region of the brain stem. The labeled axons, which are fine and unmyelinated in our material, form conventional synaptic contacts onto both relay cells and interneurons. These connections are surprisingly selective for certain postsynaptic elements such as the dendritic shafts and appendages of relay cells and the presynaptic dendritic terminals of interneurons. That is, the morphology of contacts made from parabrachial axons varies with the specific postsynaptic profile. Even a single axon can form symmetrical contacts onto F2 terminals, which are synaptic terminals deriving from dendrites of interneurons, and dendritic shafts of relay X cells, and form asymmetrical contacts onto dendritic appendages of the same relay X cells. Reconstructions of the dendritic segments postsynaptic to the labeled terminals show that the dendritic appendages receive retinal and parabrachial input in triadic relationships with F2 terminals: a retinal or parabrachial axon contacts the F2 terminal, and the F2 terminal plus the retinal or parabrachial axon contact the dendritic appendage. This positioning of the parabrachial innervation is well suited for control of retinal transmission. Finally, the dual morphology of the parabrachial synaptic contacts suggests that their actions may differ depending on the postsynaptic target. PMID:3199193

  11. The connective tissue and glial framework in the optic nerve head of the normal human eye: light and scanning electron microscopic studies.

    PubMed

    Oyama, Tokuhide; Abe, Haruki; Ushiki, Tatsuo

    2006-12-01

    The arrangement of connective tissue components (i.e., collagen, reticular, and elastic fibers) and glial elements in the optic nerve head of the human eye was investigated by the combined use of light microscopy and scanning electron microscopy (SEM). Light-microscopically, the optic nerve head could be subdivided into four parts from the different arrangements of the connective tissue framework: a surface nerve fiber layer, and prelaminar, laminar, and postlaminar regions. The surface nerve fiber layer only possessed connective tissue elements around blood vessels. In the prelaminar region, collagen fibrils, together with delicate elastic fibers, formed thin interrupted sheaths for accommodating small nerve bundles. Immunohistochemistry for the glial fibrillary acidic protein (GFAP) showed that GFAP-positive cells formed columnar structures (i.e., glial columns), with round cell bodies piled up into layers. These glial columns were located in the fibrous sheaths of collagen fibrils and elastic fibers. In the laminar region, collagen fibrils and elastic fibers ran transversely to the optic nerve axis to form a thick membranous layer - the lamina cribrosa - which had numerous round openings for accommodating optic nerve fiber bundles. GFAP-positive cellular processes also ran transversely in association with collagen and elastin components. The postlaminar region had connective tissues which linked the lamina cribrosa with fibrous sheaths for accommodating nerve bundles in the extraocular optic nerve, where GFAP-positive cells acquired characteristics typical of fibrous astrocytes. These findings indicate that collagen fibrils, as a whole, form a continuous network which serves as a skeletal framework of the optic nerve head for protecting optic nerve fibers from mechanical stress as well as for sustaining blood vessels in the optic nerve. The lamina cribrosa containing elastic fibers are considered to be plastic against the mechanical force affected by elevation

  12. Reversible reduction in dendritic spines in CA1 of rat and ground squirrel subjected to hypothermia-normothermia in vivo: A three-dimensional electron microscope study.

    PubMed

    Popov, V I; Medvedev, N I; Patrushev, I V; Ignat'ev, D A; Morenkov, E D; Stewart, M G

    2007-11-01

    A study was made at electron microscope level of changes in the three-dimensional (3-D) morphology of dendritic spines and postsynaptic densities (PSDs) in CA1 of the hippocampus in ground squirrels, taken either at low temperature during hibernation (brain temperature 2-4 degrees C), or after warming and recovery to the normothermic state (34 degrees C). In addition, the morphology of PSDs and spines was measured in a non-hibernating mammal, rat, subjected to cooling at 2 degrees C at which time core rectal temperature was 15 degrees C, and then after warming to normothermic conditions. Significant differences were found in the proportion of thin and stubby spines, and shaft synapses in CA1 for rats and ground squirrels for normothermia compared with cooling or hibernation. Hypothermia induced a decrease in the proportion of thin spines, and an increase in stubby and shaft spines, but no change in the proportion of mushroom spines. The changes in redistribution of these three categories of spines in ground squirrel are more prominent than in rat. There were no significant differences in synapse density determined for ground squirrels or rats at normal compared with low temperature. Measurement of spine and PSD volume (for mushroom and thin spines) also showed no significant differences between the two functional states in either rats or ground squirrels, nor were there any differences in distances between neighboring synapses. Spinules on dendritic shafts were notable qualitatively during hibernation, but absent in normothermia. These data show that hypothermia results in morphological changes which are essentially similar in both a hibernating and a non-hibernating animal.

  13. Intrinsic instability of aberration-corrected electron microscopes.

    PubMed

    Schramm, S M; van der Molen, S J; Tromp, R M

    2012-10-19

    Aberration-corrected microscopes with subatomic resolution will impact broad areas of science and technology. However, the experimentally observed lifetime of the corrected state is just a few minutes. Here we show that the corrected state is intrinsically unstable; the higher its quality, the more unstable it is. Analyzing the contrast transfer function near optimum correction, we define an "instability budget" which allows a rational trade-off between resolution and stability. Unless control systems are developed to overcome these challenges, intrinsic instability poses a fundamental limit to the resolution practically achievable in the electron microscope.

  14. High Cycle Fatigue in the Transmission Electron Microscope.

    PubMed

    Bufford, Daniel C; Stauffer, Douglas; Mook, William M; Syed Asif, S A; Boyce, Brad L; Hattar, Khalid

    2016-08-10

    One of the most common causes of structural failure in metals is fatigue induced by cyclic loading. Historically, microstructure-level analysis of fatigue cracks has primarily been performed post mortem. However, such investigations do not directly reveal the internal structural processes at work near micro- and nanoscale fatigue cracks and thus do not provide direct evidence of active microstructural mechanisms. In this study, the tension-tension fatigue behavior of nanocrystalline Cu was monitored in real time at the nanoscale by utilizing a new capability for quantitative cyclic mechanical loading performed in situ in a transmission electron microscope (TEM). Controllable loads were applied at frequencies from one to several hundred hertz, enabling accumulations of 10(6) cycles within 1 h. The nanometer-scale spatial resolution of the TEM allows quantitative fatigue crack growth studies at very slow crack growth rates, measured here at ∼10(-12) m·cycle(-1). This represents an incipient threshold regime that is well below the tensile yield stress and near the minimum conditions for fatigue crack growth. Evidence of localized deformation and grain growth within 150 nm of the crack tip was observed by both standard imaging and precession electron diffraction orientation mapping. These observations begin to reveal with unprecedented detail the local microstructural processes that govern damage accumulation, crack nucleation, and crack propagation during fatigue loading in nanocrystalline Cu. PMID:27351706

  15. Synaptic relationships between a multipolar stellate cell and a pyramidal neuron in the rat visual cortex. A combined Golgi-electron microscope study.

    PubMed

    Peters, A; Proskauer, C C

    1980-04-01

    Two synapsing and impregnated neurons in the rat visual cortex have been examined by a combined Golgi-electron microscope technique in which the Golgi precipitate is replaced by gold particles. One of the neurons is a stellate cell with smooth dendrites and a well impregnated axon, while the other is a layer III pyramidal neuron. Light microscopy showed some boutons from the axonal plexus of the stellate cell closely apposed to the soma and dendrites of the pyramid and it was predicted that synapses were present at these sites. An electron microscopic examination of serial thin sections, in which the profiles of the impregnated neurons are marked by their content of gold particles, showed most of these predicted synapses to exist. Indeed, axon terminals of the stellate cell formed five symmetric synapses with the cell body of the pyramid, one with the apical dendritic shaft and three with basal dendrites. Reasons are given for believing these synapses to be inhibitory. In addition, it was found that one of the axon terminals of the stellate cell synapsed with one of that cell's own dendrites. The significance of this finding is discussed.

  16. Direct current scanning field emission microscope integrated with existing scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Wang, Tong; Reece, Charles E.; Sundelin, Ronald M.

    2002-09-01

    Electron field emission (FE) from broad-area metal surfaces is known to occur at much lower electric field than predicted by Fowler-Nordheim law. Although micron or submicron particles are often observed at such enhanced field emission (EFE) sites, the strength and number of emitting sites and the causes of EFE strongly depend on surface preparation and handling, and the physical mechanism of EFE remains unknown. To systematically investigate the sources of this emission, a dc scanning field emission microscope (SFEM) has been built as an extension to an existing commercial scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer for emitter characterization. In the SFEM chamber of ultrahigh vacuum (approx10-9 Torr), a sample is moved laterally in a raster pattern (2.5 mum step resolution) under a high voltage anode microtip for field emission detection and localization. The sample is then transferred under vacuum by a hermetic retractable linear transporter to the SEM chamber for individual emitter site characterization. Artificial marks on the sample surface serve as references to convert x, y coordinates of emitters in the SFEM chamber to corresponding positions in the SEM chamber with a common accuracy of plus-or-minus100-200 mum in x and y. Samples designed to self-align in sample holders are used in each chamber, allowing them to retain position registration after non-in situ processing to track interesting features. No components are installed inside the SEM except the sample holder, which does not affect the routine operation of the SEM. The apparatus is a system of low cost and maintenance and significant operational flexibility. Field emission sources from planar niobium--the material used in high-field rf superconducting cavities for particle accelerator--have been studied after different surface preparations, and significantly reduced field emitter density has been achieved by refining the preparation process based on scan

  17. Secondary electron imaging of monolayer materials inside a transmission electron microscope

    SciTech Connect

    Cretu, Ovidiu Lin, Yung-Chang; Suenaga, Kazutomo

    2015-08-10

    A scanning transmission electron microscope equipped with a backscattered and secondary electron detector is shown capable to image graphene and hexagonal boron nitride monolayers. Secondary electron contrasts of the two lightest monolayer materials are clearly distinguished from the vacuum level. A signal difference between these two materials is attributed to electronic structure differences, which will influence the escape probabilities of the secondary electrons. Our results show that the secondary electron signal can be used to distinguish between the electronic structures of materials with atomic layer sensitivity, enhancing its applicability as a complementary signal in the analytical microscope.

  18. Foucault imaging by using non-dedicated transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Taniguchi, Yoshifumi; Matsumoto, Hiroaki; Harada, Ken

    2012-08-01

    An electron optical system for observing Foucault images was constructed using a conventional transmission electron microscope without any special equipment for Lorentz microscopy. The objective lens was switched off and an electron beam was converged by a condenser optical system to the crossover on the selected area aperture plane. The selected area aperture was used as an objective aperture to select the deflected beam for Foucault mode, and the successive image-forming lenses were controlled for observation of the specimen images. The irradiation area on the specimen was controlled by selecting the appropriate diameter of the condenser aperture.

  19. Foucault imaging by using non-dedicated transmission electron microscope

    SciTech Connect

    Taniguchi, Yoshifumi; Matsumoto, Hiroaki; Harada, Ken

    2012-08-27

    An electron optical system for observing Foucault images was constructed using a conventional transmission electron microscope without any special equipment for Lorentz microscopy. The objective lens was switched off and an electron beam was converged by a condenser optical system to the crossover on the selected area aperture plane. The selected area aperture was used as an objective aperture to select the deflected beam for Foucault mode, and the successive image-forming lenses were controlled for observation of the specimen images. The irradiation area on the specimen was controlled by selecting the appropriate diameter of the condenser aperture.

  20. High cycle fatigue in the transmission electron microscope

    DOE PAGESBeta

    Bufford, Daniel C.; Stauffer, Douglas; Mook, William M.; Syed Asif, S. A.; Boyce, Brad L.; Hattar, Khalid

    2016-06-28

    One of the most common causes of structural failure in metals is fatigue induced by cyclic loading. Historically, microstructure-level analysis of fatigue cracks has primarily been performed post mortem. However, such investigations do not directly reveal the internal structural processes at work near micro- and nanoscale fatigue cracks and thus do not provide direct evidence of active microstructural mechanisms. In this paper, the tension–tension fatigue behavior of nanocrystalline Cu was monitored in real time at the nanoscale by utilizing a new capability for quantitative cyclic mechanical loading performed in situ in a transmission electron microscope (TEM). Controllable loads were appliedmore » at frequencies from one to several hundred hertz, enabling accumulations of 106 cycles within 1 h. The nanometer-scale spatial resolution of the TEM allows quantitative fatigue crack growth studies at very slow crack growth rates, measured here at ~10–12 m·cycle–1. This represents an incipient threshold regime that is well below the tensile yield stress and near the minimum conditions for fatigue crack growth. Evidence of localized deformation and grain growth within 150 nm of the crack tip was observed by both standard imaging and precession electron diffraction orientation mapping. Finally, these observations begin to reveal with unprecedented detail the local microstructural processes that govern damage accumulation, crack nucleation, and crack propagation during fatigue loading in nanocrystalline Cu.« less

  1. Interaction-Free Quantum Electron Microscope in Free-Space

    NASA Astrophysics Data System (ADS)

    Yang, Yujia; Kim, Chung-Soo; Hobbs, Richard; Manfrinato, Vitor; Celiker, Orhan; Kruit, Pieter; Berggren, Karl

    2015-03-01

    We propose the design and theoretical analysis of a quantum electron microscope (QEM), which utilizes interaction-free quantum measurement with electrons for nanoscale imaging. The QEM can be used to image electron-irradiation-sensitive materials, such as biological samples, with a high resolution and low radiation damage. Our QEM scheme is an electron interferometer with a storage resonator. The incoming electron beam is asymmetrically split into a strong reference beam and a weak sample beam, both of which are stored in the resonator. Only the weak sample beam transmits through the sample for multiple times. We propose to build the QEM with free-space electron optics. We develop a scattering matrix method to theoretically analyze the contrast mechanism, radiation damage, and measurement accuracy. We propose an electron-mirror-based storage resonator and we have performed electron optics simulation of electron trajectories within the resonator. We also report experimental implementation and characterization of the electron beam-splitter to be used in the QEM. Thin crystals fabricated with focused ion beam and nano-gratings fabricated with electron-beam lithography are two candidate beam-splitters, both of which are characterized by electron diffraction. This work is funded by Gordon and Betty Moore Foundation.

  2. A Qualitative Analysis to Compare the Effects of Surface Machining of Conventional Denture Base Resin and Two Soft Liners: A Scanning Electron Microscopic Study

    PubMed Central

    Taruna, M.; Chittaranjan, B.; Reddy, Sushendhar M.; Reddy, Kranti Kiran E.; Kulkarni, Ganesh

    2015-01-01

    Introduction: The denture base acrylic resins require adjustments for various reasons. During this process there is an alteration in the surface characteristics of the denture base. Rough surfaces promote the bacterial adhesion and plaque accumulation; therefore it is important to know the character of the surface left by instrumentation on denture base materials. This study evaluated the surface characteristics of the machined surfaces of heat-cured acrylic denture base resin, GC supersoft and Permasoft softliners. Materials and Methods: Thirty 15×15×1.5mm acrylic resin specimens were fabricated with each of three acrylic resins: Lucitone 199 denture base resin (Group I), GC supersoft (Group II) and Permasoft (Group III) softliners. They were further divided into three sub Groups A, B and C, in which Sub Group A was control group that is smooth produced against the glass. Sub Group B was produced by machining with the tungsten carbide bur and Sub group C is machined with the stone bur. Each surface was evaluated by a Scanning electron microscope and data were analyzed by analysis of variance followed by Tukey’s HSD test. Results: Stone bur produced smoother surface (Ra 3.6681μm± 0.254) on Lucitone199 than the tungsten carbide bur (Ra 5.3881μm ± 0.3373). Carbide bur produced a smoother surface on the GC super soft (Ra 1.617097μm ± 0.191767) and Permasoft softliners (Ra 2.237419μm ± 0.354259). Whereas stone bur produced rougher surface on GC supersoft(Ra 2.6μm) and Permasoft (Ra 4.184839μm ± 0.409869) softliners. Conclusion: The present study shows each type of rotary instrument produces its own characteristic surface on each type of denture base materials and that care is needed when selecting the most appropriate instrument to adjust denture base materials. These results can have a significant clinical implication. While using Lucitone 199 stone bur can be used for chair side adjustments. Tungsten carbide bur can be used for GC supersoft and

  3. The histological investigation of gingiva from patients with chronic renal failure, renal transplants, and periodontitis: a light and electron microscopic study.

    PubMed

    Yamalik, N; Delilbasi, L; Gülay, H; Cağlayan, F; Haberal, M; Cağlayan, G

    1991-12-01

    The clinical and histological appearance of gingiva was evaluated in renal transplant recipients (RTR) receiving immunosuppressive drugs, in patients with chronic renal failure (CRF) undergoing hemodialysis, and systemically healthy individuals with periodontitis. Although the amount of bacterial plaque accumulation was similar among the groups (P greater than 0.05), the gingival inflammation was significantly less in RTR when compared to the other 2 groups (P less than 0.05). In light microscopic investigation the overall appearance of the connective tissue was similar in all of the groups. A mononuclear cell infiltration was present in all of the specimens; however, the number of inflammatory cells in patients with periodontitis was significantly higher than the other 2 groups (P less than 0.05). Prominent epithelial changes in the superficial layers of the oral epithelium; i.e., areas showing desquamation-like appearance, were noticed in patients with CRF. In electron microscopic investigation, fibroblasts and plasma cells with well-developed granular endoplasmic reticulum were found in connective tissue in RTR patients. In patients with CRF, epithelial cells presented swollen granular endoplasmic reticulum cisternae resembling vacuoles, indicating the presence of degeneration. It was suggested that with the use of immunosuppressive drugs the response to bacterial plaque did not diminish completely. PMID:1765936

  4. Computer measurement of particle sizes in electron microscope images

    NASA Technical Reports Server (NTRS)

    Hall, E. L.; Thompson, W. B.; Varsi, G.; Gauldin, R.

    1976-01-01

    Computer image processing techniques have been applied to particle counting and sizing in electron microscope images. Distributions of particle sizes were computed for several images and compared to manually computed distributions. The results of these experiments indicate that automatic particle counting within a reasonable error and computer processing time is feasible. The significance of the results is that the tedious task of manually counting a large number of particles can be eliminated while still providing the scientist with accurate results.

  5. Electron microscope evidence of virus infection in cultured marine fish

    NASA Astrophysics Data System (ADS)

    Sun, Xiu-Qin; Zhang, Jin-Xing; Qu, Ling-Yun

    2000-09-01

    Electron microscope investigation on the red sea bream ( Pagrosomus major), bastard halibut ( Paralichthys olivaceus) and stone flounder ( Kareius bicoloratus) in North China revealed virus infection in the bodies of the dead and diseased fish. These viruses included the lymphocystis disease virus (LDV), parvovirus, globular virus, and a kind of baculavirus which was not discovered and reported before and is now tentatively named baculavirus of stone flounder ( Kareius bicoloratus).

  6. Applications of the Analytical Electron Microscope to Materials Science

    NASA Technical Reports Server (NTRS)

    Goldstein, J. I.

    1992-01-01

    In the last 20 years, the analytical electron microscope (AEM) as allowed investigators to obtain chemical and structural information from less than 50 nanometer diameter regions in thin samples of materials and to explore problems where reactions occur at boundaries and interfaces or within small particles or phases in bulk samples. Examples of the application of the AEM to materials science problems are presented in this paper and demonstrate the usefulness and the future potential of this instrument.

  7. In situ electron microscope study of the phase transformation, structure and growth of thin Te 1- xSe x films

    NASA Astrophysics Data System (ADS)

    Vermaak, J. S.; Raubenheimer, D.

    1990-01-01

    An in-situ electron microscope technique was utilized to observe directly the amorphous-to-crystalline phase transformation, the isothermal growth rates, as well as the orientation and structure of the recrystallized films for the Te 1-xSe x alloy system for x=0.2, 0.3 and 0.4. Activation energies of E=0.91, 0.93 and 0.96 eV and crystallization temperatures of Tc=-14, 81.5 and 85°C for the three alloys, respectively, were found. In all three cases the crystallization process originated from single crystalline nuclei with a hexagonal structure and with the c-axis in general parallel to the substrate surface.

  8. Concurrent in situ ion irradiation transmission electron microscope

    DOE PAGESBeta

    Hattar, K.; Bufford, D. C.; Buller, D. L.

    2014-08-29

    An in situ ion irradiation transmission electron microscope has been developed and is operational at Sandia National Laboratories. This facility permits high spatial resolution, real time observation of electron transparent samples under ion irradiation, implantation, mechanical loading, corrosive environments, and combinations thereof. This includes the simultaneous implantation of low-energy gas ions (0.8–30 keV) during high-energy heavy ion irradiation (0.8–48 MeV). In addition, initial results in polycrystalline gold foils are provided to demonstrate the range of capabilities.

  9. Electron microscopic observations of amoeba proteus in growth and inanition.

    PubMed

    COHEN, A I

    1957-11-25

    Electron microscopic observations have been made on growing and dividing specimens of Amoeba proteus and also on starving animals. Structures presumably corresponding to the mitochondria, alpha particles, vacuoles, and Golgi material are described. A new entity, designated as a foamy particle, is noted. Descriptions are given of the cytoplasmic and nuclear membranes. During division the inner, thick nuclear membrane component is seen to vanish and the outer membrane persist. Measurements suggest a gradual reappearance of the inner component with growth. Starving animals show a loss of cytoplasmic granularity and an increase in the electron density of mitochondria, presumably due to lipide accumulation.

  10. A new clustering algorithm for scanning electron microscope images

    NASA Astrophysics Data System (ADS)

    Yousef, Amr; Duraisamy, Prakash; Karim, Mohammad

    2016-04-01

    A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning it with a focused beam of electrons. The electrons interact with the sample atoms, producing various signals that are collected by detectors. The gathered signals contain information about the sample's surface topography and composition. The electron beam is generally scanned in a raster scan pattern, and the beam's position is combined with the detected signal to produce an image. The most common configuration for an SEM produces a single value per pixel, with the results usually rendered as grayscale images. The captured images may be produced with insufficient brightness, anomalous contrast, jagged edges, and poor quality due to low signal-to-noise ratio, grained topography and poor surface details. The segmentation of the SEM images is a tackling problems in the presence of the previously mentioned distortions. In this paper, we are stressing on the clustering of these type of images. In that sense, we evaluate the performance of the well-known unsupervised clustering and classification techniques such as connectivity based clustering (hierarchical clustering), centroid-based clustering, distribution-based clustering and density-based clustering. Furthermore, we propose a new spatial fuzzy clustering technique that works efficiently on this type of images and compare its results against these regular techniques in terms of clustering validation metrics.

  11. Visualizing bone porosities using a tabletop scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, D.; DaPonte, J.; Broadbridge, C. C.; Daniel, D.; Alter, L.

    2010-04-01

    Pores are naturally occurring entities in bone. Changes in pore size and number are often associated with diseases such as Osteoporosis and even microgravity during spaceflight. Studying bone perforations may yield great insight into bone's material properties, including bone density and may contribute to identifying therapies to halt or potentially reverse bone loss. Current technologies used in this field include nuclear magnetic resonance, micro-computed tomography and the field emission scanning electron microscope (FE-SEM) 2, 5. However, limitations in each method limit further advancement. The objective of this study was to assess the effectiveness of using a new generation of analytical instruments, the TM-1000 tabletop, SEM with back-scatter electron (BSE) detector, to analyze cortical bone porosities. Hind limb unloaded and age-based controlled mouse femurs were extracted and tested in vitro for changes in pores on the periosteal surface. An important advantage of using the tabletop is the simplified sample preparation that excludes extra coatings, dehydration and fixation steps that are otherwise required for conventional SEM. For quantitative data, pores were treated as particles in order to use an analyze particles feature in the NIH ImageJ software. Several image-processing techniques for background smoothing, thresholding and filtering were employed to produce a binary image suitable for particle analysis. It was hypothesized that the unloaded bones would show an increase in pore area, as the lack of mechanical loading would affect bone-remodeling processes taking place in and around pores. Preliminary results suggest only a slight different in frequency but not in size of pores between unloaded and control femurs.

  12. STEM electron tomography in the Scanning Electron Microscope

    NASA Astrophysics Data System (ADS)

    Ferroni, M.; Signoroni, A.; Sanzogni, A.; Sberveglieri, G.; Migliori, A.; Ortolani, L.; Christian, M.; Masini, L.; Morandi, V.

    2015-10-01

    The scanning-transmission imaging mode in the SEM allows for the threedimensional tomographic reconstruction of a specimen, starting from a set of projection images. Compressed sensing was used to solve the undetermined problem of structure reconstruction and was proven capable of overcoming the limitations arising from the sampling scheme. Reconstructions of cobalt particles within a carbon nanotube and collagen fibrils in a dermal tissue are presented, demonstrating the potential of this technique in the set of 3-D electron microscopy methods for both physical and biological science.

  13. An innovative coating technique for light and electron microscopic autoradiography.

    PubMed

    Kornhauser, G V; Krum, J M; Rosenstein, J M

    1992-06-01

    We describe a modified nuclear emulsion coating technique for both electron and light microscopic autoradiography. We propose that by reversing the application of formvar film so that it adheres to and covers thin sections placed on grids, we have developed a technically accessible methodology that produces optimal conditions for the tracing of specific nuclear activity. A smooth, continuous base is formed over the sections on which a monolayer of evenly packed silver halide crystals can be applied by dip-coating. The same principle is applied to pre-stained 1-micron plastic sections of glass slides. We suggest that the application of formvar film over thin sections does not impede or interfere with the exposure of the emulsion by the labeled tissue. On the contrary, it virtually eliminates contamination and background radiation, enhancing the specificity and quality of resolution at even low magnifications. This technical modification, which facilitates the application of the emulsion, could render electron microscopic autoradiography a routine laboratory procedure, allowing for easily reproducible results and quantitative evaluation. At the light microscopic level, this technique prevents chemical fogging caused by certain stains, and thus allows routine pre-staining before coating with emulsion.

  14. Photocathode Optimization for a Dynamic Transmission Electron Microscope: Final Report

    SciTech Connect

    Ellis, P; Flom, Z; Heinselman, K; Nguyen, T; Tung, S; Haskell, R; Reed, B W; LaGrange, T

    2011-08-04

    The Dynamic Transmission Electron Microscope (DTEM) team at Harvey Mudd College has been sponsored by LLNL to design and build a test setup for optimizing the performance of the DTEM's electron source. Unlike a traditional TEM, the DTEM achieves much faster exposure times by using photoemission from a photocathode to produce electrons for imaging. The DTEM team's work is motivated by the need to improve the coherence and current density of the electron cloud produced by the electron gun in order to increase the image resolution and contrast achievable by DTEM. The photoemission test setup is nearly complete and the team will soon complete baseline tests of electron gun performance. The photoemission laser and high voltage power supply have been repaired; the optics path for relaying the laser to the photocathode has been finalized, assembled, and aligned; the internal setup of the vacuum chamber has been finalized and mostly implemented; and system control, synchronization, and data acquisition has been implemented in LabVIEW. Immediate future work includes determining a consistent alignment procedure to place the laser waist on the photocathode, and taking baseline performance measurements of the tantalum photocathode. Future research will examine the performance of the electron gun as a function of the photoemission laser profile, the photocathode material, and the geometry and voltages of the accelerating and focusing components in the electron gun. This report presents the team's progress and outlines the work that remains.

  15. Electron irradiation-induced destruction of carbon nanotubes in electron microscopes.

    PubMed

    Mølhave, Kristian; Gudnason, Sven Bjarke; Pedersen, Anders Tegtmeier; Clausen, Casper Hyttel; Horsewell, Andy; Bøggild, Peter

    2007-12-01

    Observations of carbon nanotubes under exposure to electron beam irradiation in standard transmission electron microscope (TEM) and scanning electron microscope (SEM) systems show that such treatment in some cases can cause severe damage of the nanotube structure, even at electron energies far below the approximate 100 keV threshold for knock-on damage displacing carbon atoms in the graphene structure. We find that the damage we observe in one TEM can be avoided by use of a cold finger. This and the morphology of the damage imply that water vapour, which is present as a background gas in many vacuum chambers, can damage the nanotube structure through electron beam-induced chemical reactions. Though, the dependence on the background gas makes these observations specific for the presently used systems, the results demonstrate the importance of careful assessment of the level of subtle structural damage that the individual electron microscope system can do to nanostructures during standard use. PMID:17445986

  16. Simulation of magnetic circular dichroism in the electron microscope

    NASA Astrophysics Data System (ADS)

    Rubino, Stefano; Schattschneider, Peter; Rusz, Jan; Verbeeck, Johan; Leifer, Klaus

    2010-12-01

    As electron energy-loss spectroscopy (EELS) and x-ray absorption spectroscopy (XAS) probe the same transitions from core-shell states to unoccupied states above the Fermi energy, it should always be possible to apply the two techniques to the same physical phenomena, such as magnetic dichroism, and obtain the same information. Indeed, the similarity in the expression of the electron and x-ray cross-sections had been already exploited to prove the equivalence of x-ray magnetic linear dichroism and anisotropy in EELS, by noting that the polarization vector of a photon plays the same role as the momentum transfer in electron scattering. Recently, the same was proven true for x-ray magnetic circular dichroism (XMCD) by establishing a new TEM technique called EMCD (electron energy-loss magnetic chiral dichroism) (Schattschneider P et al 2006 Nature 441 486-8), which makes use of special electron scattering conditions to force the absorption of a circularly polarized virtual photon. The intrinsic advantage of EMCD over XMCD is the high spatial resolution of electron microscopes, which are readily available. Among the particular obstacles in EMCD that do not exist for synchrotron radiation, is the notoriously low signal and the very particular scattering conditions necessary to observe a chiral dichroic signal. In spite of that, impressive progress has been made in recent years. The signal strength could be considerably increased, and some innovations such as using a convergent beam have been introduced. EMCD has evolved into several techniques, which make full use of the versatility of the TEM and energy filtering, spectroscopy or STEM conditions (Rubino S 2007 Magnetic circular dichroism in the transmission electron microscope PhD Thesis Vienna University of Technology, Vienna, Austria).

  17. A METHOD FOR INTRACELLULAR AUTORADIOGRAPHY IN THE ELECTRON MICROSCOPE.

    PubMed

    Silk, M H; Hawtrey, A O; Spence, I M; Gear, J H

    1961-08-01

    A technic is described for high resolution intracellular autoradiography in the electron microscope. Cultures of LLC-MK(2) monkey kidney cells were incubated for 72 hours in a medium containing 0.4 microcurie per ml of thymidine-H(3). After labeling, the cells were fixed with osmium tetroxide and embedded in methacrylate. Ultrathin sections of the labeled tissue were taken up on Formvar-coated and carbon-stabilized electron microscope grids. A 150 to 450 A layer of silver metal was then evaporated onto the tissue. The coated grids were exposed to bromine vapor for 1.5 to 2 minutes under red light, allowed to dry for 1 minute, and then covered with a thin film of 1 per cent aqueous gelatin applied by means of a fine wire loop lowered over the grid supported on a glass peg. For autoradiographic exposure, the grids were stored 50 days in a light-proof container at 4 degrees C with calcium chloride desiccant. Development was carried out for 5 minutes at 20 degrees C in Promicrol (May and Baker, England) diluted 1:1 with water, followed by a 1 minute water wash and fixation for 2.5 minutes in 15 per cent aqueous sodium thiosulphate. After removal of the gelatin by immersion for 16 hours in water at 37 degrees C, the autoradiograms were dried and examined in the electron microscope. Ultrastructural detail was fairly well defined and the cytoplasm of each labeled cell was covered with an electron opaque deposit of silver, suggesting that a polynucleotide containing thymidine may be synthesized in the cytoplasm. The matter is discussed.

  18. In situ laser processing in a scanning electron microscope

    SciTech Connect

    Roberts, Nicholas A.; Magel, Gregory A.; Hartfield, Cheryl D.; Moore, Thomas M.; Fowlkes, Jason D.; Rack, Philip D.

    2012-07-15

    Laser delivery probes using multimode fiber optic delivery and bulk focusing optics have been constructed and used for performing materials processing experiments within scanning electron microscope/focused ion beam instruments. Controlling the current driving a 915-nm semiconductor diode laser module enables continuous or pulsed operation down to sub-microsecond durations, and with spot sizes on the order of 50 {mu}m diameter, achieving irradiances at a sample surface exceeding 1 MW/cm{sup 2}. Localized laser heating has been used to demonstrate laser chemical vapor deposition of Pt, surface melting of silicon, enhanced purity, and resistivity via laser annealing of Au deposits formed by electron beam induced deposition, and in situ secondary electron imaging of laser induced dewetting of Au metal films on SiO{sub x}.

  19. Integrated windows-based control system for an electron microscope

    NASA Astrophysics Data System (ADS)

    Ruan, Shengyang; Kapp, Oscar H.

    1994-12-01

    A Windows application has been developed for management and operation of beam instruments such as electron or ion microscopes. It provides a facility that allows an operator to manage a complicated instrument with minimal effort, primarily under mouse control. The hardware control components used on similar instruments (e.g., the scanning transmission electron microscopes in our lab), such as toggles, buttons, and potentiometers for adjustments on various scales, are all replaced by the controls of the Windows application and are addressable on a single screen. The new controls in this program (via adjustable software settings) offer speed of response and smooth operation providing tailored control of various instrument parameters. Along with the controls offering single parameter adjustment, a two-dimensional control was developed that allows two parameters to be coupled and addressed simultaneously. This capability provides convenience for such tasks as ``finding the beam'' and directing it to a location of interest on the specimen. Using an icon-based display, this Windows application provides better integrated and more robust information for monitoring instrument status than the indicators and meters of the traditional instrument controls. As a Windows application, this program is naturally able to share the resources of the Windows system and is thus able to link to many other applications such as our image acquisition and processing programs. Computer control provides automatic protection and instant diagnostics for the experimental instrument. This Windows application is fully functional and is in daily use to control a new type of electron microscope developed in our lab.

  20. The human chromosome. Electron microscopic observations on chromatin fiber organization.

    PubMed

    Abuelo, J G; Moore, D E

    1969-04-01

    Human lymphocytes were grown in short-term tissue culture and were arrested in metaphase with Colcemid. Their chromosomes were prepared by the Langmuir trough-critical point drying technique and were examined under the electron microscope. In addition, some chromosomes were digested with trypsin, Pronase, or DNase. The chromosomes consist entirely of tightly packed, 240 +/- 50-A chromatin fibers. Trypsin and Pronase treatments induce relaxation of fiber packing and reveal certain underlying fiber arrangements. Furthermore, trypsin treatment demonstrates that the chromatin fiber has a 25-50 A trypsin-resistant core surrounded by a trypsin-sensitive sheath. DNase digestion suggests that this core contains DNA.

  1. Sizing melamine-formaldehyde microspheres using an electron microscope

    NASA Astrophysics Data System (ADS)

    Garee, M.; Sheridan, T. E.

    2006-03-01

    Melamine-formaldehyde (MF) microspheres are widely used in complex plasma experiments because they are nearly monodisperse and are available in a wide variety of diameters. The manufacturer of these particles characterizes their mean diameter and standard deviation using a Coulter multisizer. However, measurements in complex plasma experiments, particularly of gas drag forces, indicate that the particles are smaller than their stated diameter. We have measured particle sizes using a scanning electron microscope and will compare these to the nominal diameter of 9.62±0.09 μm.

  2. Characteristics of different frequency ranges in scanning electron microscope images

    SciTech Connect

    Sim, K. S. Nia, M. E.; Tan, T. L.; Tso, C. P.; Ee, C. S.

    2015-07-22

    We demonstrate a new approach to characterize the frequency range in general scanning electron microscope (SEM) images. First, pure frequency images are generated from low frequency to high frequency, and then, the magnification of each type of frequency image is implemented. By comparing the edge percentage of the SEM image to the self-generated frequency images, we can define the frequency ranges of the SEM images. Characterization of frequency ranges of SEM images benefits further processing and analysis of those SEM images, such as in noise filtering and contrast enhancement.

  3. Microcircuit failure analysis using the SEM. [Scanning Electron Microscopes

    NASA Technical Reports Server (NTRS)

    Nicolas, D. P.

    1974-01-01

    The scanning electron microscope adds a new dimension to the knowledge that can be obtained from a failed microcircuit. When used with conventional techniques, SEM assists and clarifies the analysis, but it does not replace light microscopy. The most advantageous features for microcircuit analysis are long working distances and great depth of field. Manufacturer related failure modes of microcircuits are metallization defects, poor bonding, surface and particle contamination, and design and fabrication faults. User related failure modes are caused by abuse, such as overstress. The Physics of Failure Procedure followed by the Astrionics Laboratory in failure analysis is described, which is designed to obtain maximum information available from each step.

  4. Stages in follicle cell/oocyte interface during vitellogenesis in caecilians Ichthyophis tricolor and Gegeneophis ramaswamii: a transmission electron-microscopic study.

    PubMed

    Beyo, Reston Saroja; Divya, Lekha; Smita, Mathew; Oommen, Oommen Vilaverthottathil; Akbarsha, Mohammed Abdulkader

    2008-02-01

    We describe the ultrastructural organization of the vitellogenic follicle stages in two caecilian species. Monthly samples of slices of ovary of Ichthyophis tricolor and Gegeneophis ramaswamii from the Western Ghats of India were subjected to transmission electron-microscopic analysis, with special attention to the follicle cell/oocyte interface. In order to maintain uniformity of the stages among the amphibians, all the stages in the caecilian follicles were assigned to stages I-VI, the vitellogenic and post-vitellogenic follicles being assigned to stages III-VI. Stage III commences with the appearance of precursors of vitelline envelope material in the perivitelline space. Stages IV and V have been assigned appropriate substages. During the transition of stage III to stage VI oocytes, a sequential change occurs in the manifestations of follicle cells, perivitelline space, vitelline envelope and oocyte cortex. The vitelline envelope becomes a tough coat through the tunnels of which the macrovilli pass to interdigitate between the microvilli. The oocyte surface forms pinocytic vesicles that develop into coated pits and, later, coated vesicles. Contributions of the oocyte cortex to the vitelline envelope and of the follicle cells to yolk material via synthesis within them are indicated. The follicle cell/oocyte interface of vitellogenic follicles of these two caecilians resembles that in anurans and urodeles, with certain features being unique to caecilians. Thus, this paper throws light on the possible relationships of caecilians to anurans and urodeles with special reference to ovarian follicles.

  5. Effect of diode laser and ultrasonics with and without ethylenediaminetetraacetic acid on smear layer removal from the root canals: A scanning electron microscope study

    PubMed Central

    Amin, Khalid; Masoodi, Ajaz; Nabi, Shahnaz; Ahmad, Parvaiz; Farooq, Riyaz; Purra, Aamir Rashid; Ahangar, Fayaz Ahmad

    2016-01-01

    Aim: To evaluate the effect of diode laser and ultrasonics with and without ethylenediaminetetraacetic acid (EDTA) on the smear layer removal from root canals. Materials and Methods: A total of 120 mandibular premolars were decoronated to working the length of 12 mm and prepared with protaper rotary files up to size F3. Group A canals irrigated with 1 ml of 3% sodium hypochlorite (NaOCl) followed by 3 ml of 3% NaOCl. Group B canals irrigated with 1 ml of 17% EDTA followed by 3 ml of 3% NaOCl. Group C canals lased with a diode laser. Group D canals were initially irrigated with 0.8 ml of 17% EDTA the remaining 0.2 ml was used to fill the root canals, and diode laser application was done. Group E canals were irrigated with 1 ml distilled water with passive ultrasonic activation, followed by 3 ml of 3% NaOCl. Group F canals were irrigated with 1 ml EDTA with passive ultrasonic activation, followed by 3 ml of 3% NaOCl. Scanning electron microscope examination of canals was done for remaining smear layer at coronal middle and apical third levels. Results: Ultrasonics with EDTA had the least smear layer scores. Conclusion: Diode laser alone performed significantly better than ultrasonics. PMID:27656060

  6. Effect of diode laser and ultrasonics with and without ethylenediaminetetraacetic acid on smear layer removal from the root canals: A scanning electron microscope study

    PubMed Central

    Amin, Khalid; Masoodi, Ajaz; Nabi, Shahnaz; Ahmad, Parvaiz; Farooq, Riyaz; Purra, Aamir Rashid; Ahangar, Fayaz Ahmad

    2016-01-01

    Aim: To evaluate the effect of diode laser and ultrasonics with and without ethylenediaminetetraacetic acid (EDTA) on the smear layer removal from root canals. Materials and Methods: A total of 120 mandibular premolars were decoronated to working the length of 12 mm and prepared with protaper rotary files up to size F3. Group A canals irrigated with 1 ml of 3% sodium hypochlorite (NaOCl) followed by 3 ml of 3% NaOCl. Group B canals irrigated with 1 ml of 17% EDTA followed by 3 ml of 3% NaOCl. Group C canals lased with a diode laser. Group D canals were initially irrigated with 0.8 ml of 17% EDTA the remaining 0.2 ml was used to fill the root canals, and diode laser application was done. Group E canals were irrigated with 1 ml distilled water with passive ultrasonic activation, followed by 3 ml of 3% NaOCl. Group F canals were irrigated with 1 ml EDTA with passive ultrasonic activation, followed by 3 ml of 3% NaOCl. Scanning electron microscope examination of canals was done for remaining smear layer at coronal middle and apical third levels. Results: Ultrasonics with EDTA had the least smear layer scores. Conclusion: Diode laser alone performed significantly better than ultrasonics.

  7. Stages in follicle cell/oocyte interface during vitellogenesis in caecilians Ichthyophis tricolor and Gegeneophis ramaswamii: a transmission electron-microscopic study.

    PubMed

    Beyo, Reston Saroja; Divya, Lekha; Smita, Mathew; Oommen, Oommen Vilaverthottathil; Akbarsha, Mohammed Abdulkader

    2008-02-01

    We describe the ultrastructural organization of the vitellogenic follicle stages in two caecilian species. Monthly samples of slices of ovary of Ichthyophis tricolor and Gegeneophis ramaswamii from the Western Ghats of India were subjected to transmission electron-microscopic analysis, with special attention to the follicle cell/oocyte interface. In order to maintain uniformity of the stages among the amphibians, all the stages in the caecilian follicles were assigned to stages I-VI, the vitellogenic and post-vitellogenic follicles being assigned to stages III-VI. Stage III commences with the appearance of precursors of vitelline envelope material in the perivitelline space. Stages IV and V have been assigned appropriate substages. During the transition of stage III to stage VI oocytes, a sequential change occurs in the manifestations of follicle cells, perivitelline space, vitelline envelope and oocyte cortex. The vitelline envelope becomes a tough coat through the tunnels of which the macrovilli pass to interdigitate between the microvilli. The oocyte surface forms pinocytic vesicles that develop into coated pits and, later, coated vesicles. Contributions of the oocyte cortex to the vitelline envelope and of the follicle cells to yolk material via synthesis within them are indicated. The follicle cell/oocyte interface of vitellogenic follicles of these two caecilians resembles that in anurans and urodeles, with certain features being unique to caecilians. Thus, this paper throws light on the possible relationships of caecilians to anurans and urodeles with special reference to ovarian follicles. PMID:18030494

  8. Electric field stimulation setup for photoemission electron microscopes.

    PubMed

    Buzzi, M; Vaz, C A F; Raabe, J; Nolting, F

    2015-08-01

    Manipulating magnetisation by the application of an electric field in magnetoelectric multiferroics represents a timely issue due to the potential applications in low power electronics and the novel physics involved. Thanks to its element sensitivity and high spatial resolution, X-ray photoemission electron microscopy is a uniquely suited technique for the investigation of magnetoelectric coupling in multiferroic materials. In this work, we present a setup that allows for the application of in situ electric and magnetic fields while the sample is analysed in the microscope. As an example of the performances of the setup, we present measurements on Ni/Pb(Mg(0.66)Nb(0.33))O3-PbTiO3 and La(0.7)Sr(0.3)MnO3/PMN-PT artificial multiferroic nanostructures.

  9. Electric field stimulation setup for photoemission electron microscopes

    SciTech Connect

    Buzzi, M.; Vaz, C. A. F.; Raabe, J.; Nolting, F.

    2015-08-15

    Manipulating magnetisation by the application of an electric field in magnetoelectric multiferroics represents a timely issue due to the potential applications in low power electronics and the novel physics involved. Thanks to its element sensitivity and high spatial resolution, X-ray photoemission electron microscopy is a uniquely suited technique for the investigation of magnetoelectric coupling in multiferroic materials. In this work, we present a setup that allows for the application of in situ electric and magnetic fields while the sample is analysed in the microscope. As an example of the performances of the setup, we present measurements on Ni/Pb(Mg{sub 0.66}Nb{sub 0.33})O{sub 3}-PbTiO{sub 3} and La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/PMN-PT artificial multiferroic nanostructures.

  10. Electric field stimulation setup for photoemission electron microscopes.

    PubMed

    Buzzi, M; Vaz, C A F; Raabe, J; Nolting, F

    2015-08-01

    Manipulating magnetisation by the application of an electric field in magnetoelectric multiferroics represents a timely issue due to the potential applications in low power electronics and the novel physics involved. Thanks to its element sensitivity and high spatial resolution, X-ray photoemission electron microscopy is a uniquely suited technique for the investigation of magnetoelectric coupling in multiferroic materials. In this work, we present a setup that allows for the application of in situ electric and magnetic fields while the sample is analysed in the microscope. As an example of the performances of the setup, we present measurements on Ni/Pb(Mg(0.66)Nb(0.33))O3-PbTiO3 and La(0.7)Sr(0.3)MnO3/PMN-PT artificial multiferroic nanostructures. PMID:26329198

  11. Electric field stimulation setup for photoemission electron microscopes

    NASA Astrophysics Data System (ADS)

    Buzzi, M.; Vaz, C. A. F.; Raabe, J.; Nolting, F.

    2015-08-01

    Manipulating magnetisation by the application of an electric field in magnetoelectric multiferroics represents a timely issue due to the potential applications in low power electronics and the novel physics involved. Thanks to its element sensitivity and high spatial resolution, X-ray photoemission electron microscopy is a uniquely suited technique for the investigation of magnetoelectric coupling in multiferroic materials. In this work, we present a setup that allows for the application of in situ electric and magnetic fields while the sample is analysed in the microscope. As an example of the performances of the setup, we present measurements on Ni/Pb(Mg0.66Nb0.33)O3-PbTiO3 and La0.7Sr0.3MnO3/PMN-PT artificial multiferroic nanostructures.

  12. Direct electron density modulation of surface plasmons with a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Saito, Yuika; Fujita, Katsumasa

    2015-01-01

    The optical properties of localized surface plasmon resonance (LSPR) were modulated by direct electron injection using scanning electron microscopy (SEM). The predictions of electromagnetic theory for LSPR on charged metal nanoparticles were experimentally verified using a novel microscopic system. Extinction spectra were obtained for gold nanostructures that were under intense electron irradiation using an SEM system equipped with an optical microscope. High-frequency shifts of LSPR were observed for a single gold nanosphere, nanodimer, and nanorod, and the amount of the shifts was explained with respect to their symmetry.

  13. A new apparatus for electron tomography in the scanning electron microscope

    SciTech Connect

    Morandi, V. Maccagnani, P.; Masini, L.; Migliori, A.; Ortolani, L.; Pezza, A.; Del Marro, M.; Pallocca, G.; Vinciguerra, P.; Rossi, M.; Ferroni, M.; Sberveglieri, G.; Vittori-Antisari, M.

    2015-06-23

    The three-dimensional reconstruction of a microscopic specimen has been obtained by applying the tomographic algorithm to a set of images acquired in a Scanning Electron Microscope. This result was achieved starting from a series of projections obtained by stepwise rotating the sample under the beam raster. The Scanning Electron Microscope was operated in the scanning-transmission imaging mode, where the intensity of the transmitted electron beam is a monotonic function of the local mass-density and thickness of the specimen. The detection strategy has been implemented and tailored in order to maintain the projection requirement over the large tilt range, as required by the tomographic workflow. A Si-based electron detector and an eucentric-rotation specimen holder have been specifically developed for the purpose.

  14. Precession electron diffraction and its utility for structural fingerprinting in the transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Moeck, Peter; Rouvimov, Sergei; Nicolopoulos, Stavros

    2009-09-01

    Precession electron diffraction (PED) in a transmission electron microscope (TEM) is discussed in order to illustrate its utility for structural fingerprinting of nanocrystals. While individual nanocrystals may be fingerprinted structurally from PED spot patterns, ensembles of nanocrystals may be fingerprinted from powder PED ring patterns.

  15. Observation of semiconductor superstructures with backscattered electrons in a scanning electron microscope

    SciTech Connect

    Bosacchi, A.; Franchi, S.; Govoni, D.; Mattei, G.; Merli, P.G.; Migliori, A.; Nacucchi, M.

    1995-12-31

    Observations of semiconductor superstructures with backscattered electrons in a scanning electron microscope have been used to revisit the concept of resolution of the backscattering imaging mode. It will be shown that the generation volume doesn`t represent in itself a limit to the resolution, which depends only on the beam size and the signal to noise ratio.

  16. Damage-free vibrational spectroscopy of biological materials in the electron microscope

    PubMed Central

    Rez, Peter; Aoki, Toshihiro; March, Katia; Gur, Dvir; Krivanek, Ondrej L.; Dellby, Niklas; Lovejoy, Tracy C.; Wolf, Sharon G.; Cohen, Hagai

    2016-01-01

    Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an ‘aloof' electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies <1 eV can be ‘safely' investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C–H, N–H and C=O vibrational signatures with no observable radiation damage. The technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ∼10 nm, simultaneously combined with imaging in the electron microscope. PMID:26961578

  17. A new method of magnifying photographic images using the scanning electron microscope in the backscattered electron detection mode

    SciTech Connect

    Frasca, P.; Galkin, B.; Feig, S.; Muir, H.; Soriano, R.; Kaufman, H.

    1982-01-01

    This paper describes a new method of magnifying small images in photographic film by means of a scanning electron microscope (SEM) operated in the backscattered electron detection mode. The study included tests of several types of radiographic film, transmission electron microscopy film, and black and white 35 mm film. The electron optical enlargement method is particularly useful in situations where the film sample is opaque to light and for generating enlarged images at magnifications beyond the reach of light optical enlargement methods, i.e. up to approximately 2000X with ease and rapidity in a single step. The electron optical enlargements compare favorably in contrast and detail with the enlargements made with a light microscope and with a darkroom enlarger.

  18. Recycling stainless steel orthodontic brackets with Er:YAG laser – An environmental scanning electron microscope and shear bond strength study

    PubMed Central

    Chacko, Prince K; Kodoth, Jithesh; John, Jacob; Kumar, Kishore

    2013-01-01

    Aim: To determine the efficiency of erbium: Yttrium aluminum garnet (Er:YAG) laser with Environmental Scanning Electron Microscope (ESEM) and shear bond strength analysis as a method of recycling stainless steel orthodontic brackets and compare with other methods of recycling. Materials and Methods: Eighty samples of extracted premolar teeth bonded to SS brackets were tested for rebonded shear bond strength after recycling by four methods and compared with a control group of 20 samples. These 80 samples were randomized into four groups which were recycled by four methods, namely, sandblasting, thermal method, adhesive grinding by tungsten carbide bur, and Er: YAG laser method. After recycling, ESEM and shear bond strength analysis were used to analyze the efficiency of the recycling methods Results: Er: YAG laser group was found to be having the greatest bond strength among the recycled brackets (8.33±2.51 followed by the sandblasting at 6.12±1.12 MPa, thermal and electropolishing at 4.44±0.95 MPa, and lastly the adhesive grinding method at 3.08±1.07 MPa. The shear bond strength of Er: YAG laser group was found to be having no statistically significant difference with that of the control group (P>0.05 and had statistical signifance with sandblasting, thermal and electropolishing and adhesive grinding groups at P>0.001. ESEM analysis showed complete removal of adhesive from the brackets recycled with Er: YAG laser which mimicked that of the control group. Conclusion: Er: YAG laser (2940 nm) was found to be the most efficient method for recycling, followed by the sandblasting, thermal, and the tungsten carbide methods, which had the least shear bond strength value and is not fit for clinical usage. PMID:24987647

  19. The border between the central and the peripheral nervous system in the cat cochlear nerve: a light and scanning electron microscopical study.

    PubMed

    Osen, Kirsten K; Furness, David N; Hackney, Carole M

    2011-07-01

    The transition between the central (CNS) and peripheral nervous system (PNS) in cranial and spinal nerve roots, referred to here as the CNS-PNS border, is of relevance to nerve root disorders and factors that affect peripheral-central regeneration. Here, this border is described in the cat cochlear nerve using light microscopical sections, and scanning electron microscopy of the CNS-PNS interfaces exposed by fracture of the nerve either prior to or following critical point drying. The CNS-PNS border represents an abrupt change in type of myelin, supporting elements, and vascularization. Because central myelin is formed by oligodendrocytes and peripheral myelin by Schwann cells, the myelinated fibers are as a rule equipped with a node of Ranvier at the border passage. The border is shallower and smoother in cat cochlear nerve than expected from other nerves, and the borderline nodes are largely in register. The loose endoneurial connective tissue of the PNS compartment is closed at the border by a compact glial membrane, the mantle zone, of the CNS compartment. The mantle zone is penetrated by the nerve fibers, but is otherwise composed of astrocytes and their interwoven processes like the external limiting membrane of the brain surface with which it is continuous. The distal surface of the mantle zone is covered by a fenestrated basal lamina. Only occasional vessels traverse the border. From an anatomical point of view, the border might be expected to be a weak point along the cochlear nerve and thus vulnerable to trauma. In mature animals, the CNS-PNS border presents a barrier to regrowth of regenerating nerve fibers and to invasion of the CNS by Schwann cells. An understanding of this region in the cochlear nerve is therefore relevant to head injuries that lead to hearing loss, to surgery on acoustic Schwannomas, and to the possibility of cochlear nerve regeneration.

  20. [The study of Balantidium Helenae Bezzenberger, 1904 (Litostomatea, Trichostomatia) inhabiting the intestines of the frog Rana temporaria Linnaeus, 1758, in optical and electron microscopes].

    PubMed

    Kornilova, O A; Chistyakova, L V

    2014-01-01

    The structure of the ciliate Balantidium helenae Bezzenberger, 1904 was investigated with the use of optical and electron microscopy. It was demonstrated that, together with the basic dimensional characteristics, main distinguishing features of the studied species include the following characters: the presence of a pointed prominence on the posterior margin of the cell; the presence of elongated cilia on the left margin of the vestibulum; and different shape and size of cortical ridges. Two morphologically different types of electron-dense bodies (supposedly hydrogenosoms) and also endobiotic bacteria were also found in the cytoplasm of B. helenae.

  1. Simulation and Characterization of a Miniaturized Scanning Electron Microscope

    NASA Technical Reports Server (NTRS)

    Gaskin, Jessica A.; Jerman, Gregory A.; Medley, Stephanie; Gregory, Don; Abbott, Terry O.; Sampson, Allen R.

    2011-01-01

    A miniaturized Scanning Electron Microscope (mSEM) for in-situ lunar investigations is being developed at NASA Marshall Space Flight Center with colleagues from the University of Alabama in Huntsville (UAH), Advanced Research Systems (ARS), the University of Tennessee in Knoxville (UTK) and Case Western Reserve University (CWRU). This effort focuses on the characterization of individual components of the mSEM and simulation of the complete system. SEMs can provide information on the size, shape, morphology and chemical composition of lunar regolith. Understanding these basic properties will allow us to better estimate the challenges associated with In-Situ Resource Utilization and to improve our basic science knowledge of the lunar surface (either precluding the need for sample return or allowing differentiation of unique samples to be returned to Earth.) The main components of the mSEM prototype includes: a cold field emission electron gun (CFEG), focusing lens, deflection/scanning system and backscatter electron detector. Of these, the electron gun development is of particular importance as it dictates much of the design of the remaining components. A CFEG was chosen for use with the lunar mSEM as its emission does not depend on heating of the tungsten emitter (lower power), it offers a long operation lifetime, is orders of magnitude brighter than tungsten hairpin guns, has a small source size and exhibits low beam energy spread.

  2. A microscopic theory of desorption induced by electronic transitions

    NASA Astrophysics Data System (ADS)

    Kasai, Hideaki; Okiji, Ayao; Tsuchiura, Hiroki

    1996-08-01

    Desorption induced by electronic transitions (DIET) in two cases is investigated from a microscopic point of view. In case A, where a single electron in a state of the localized kind (localized around adsorbates) is excited into a state of the extended kind (extended into the bosom of the substrate), the shape of the excited-state potential-energy surface (PES) may differ markedly from that of the ground-state PES for adsorbate motion. The Franck-Condon factor then takes a finite value, giving rise to a finite desorption probability. In case B, where a single electron in a state of the extended kind is excited into another state of the extended kind, the shape of the excited-state PES is practically the same as that of the ground-state PES. The Frank-Condon factor is then zero. In such a case, one should take DIET as a single-step (coherent) process and take into account the adsorbate-position dependence of the matrix element for state transitions of the electron system in order to obtain a finite desorption probability.

  3. Miniature self-contained vacuum compatible electronic imaging microscope

    DOEpatents

    Naulleau, Patrick P.; Batson, Phillip J.; Denham, Paul E.; Jones, Michael S.

    2001-01-01

    A vacuum compatible CCD-based microscopic camera with an integrated illuminator. The camera can provide video or still feed from the microscope contained within a vacuum chamber. Activation of an optional integral illuminator can provide light to illuminate the microscope subject. The microscope camera comprises a housing with a objective port, modified objective, beam-splitter, CCD camera, and LED illuminator.

  4. In situ nanoindentation in a transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Minor, Andrew Murphy

    This dissertation presents the development of the novel mechanical testing technique of in situ nanoindentation in a transmission electron microscope (TEM). This technique makes it possible to simultaneously observe and quantify the mechanical behavior of nano-scale volumes of solids. Chapter 2 details the unique specimen preparation techniques employed to meet the geometrical constraints of the in situ experiments. These techniques include bulk silicon micromachining and the use of a focused ion beam. In section 2.4 a method of voltage-controlled mechanical testing is derived theoretically and proven experimentally. This method enables the quantification of the mechanical behavior during in situ nanoindentation experiments. Three classes of material systems were studied with this new technique: (1) bulk single crystal, (2) a soft thin film on a harder substrate and (3) a hard thin film on a softer substrate. Section 3.2 provides the first direct evidence of dislocation nucleation in single crystal silicon at room temperature. In contrast to the observation of phase transformations during conventional indentation experiments, the unique geometry employed for the in situ experiments resulted in dislocation plasticity. In section 3.3 results from in situ nanoindentation of Al films on Si substrates are presented. These results include the correlation of the microstructural deformation behavior with load vs. displacement data. It is shown that a sharp change in the force-displacement response at the elastic-to-plastic transition signifies the nucleation of dislocations. Additionally, the softening of sub-micron grains with size is observed. Section 3.4 discussed the influence of the substrate on the indentation response of two thin film/substrate systems where the films were harder than the substrate. Amorphous diamond on Si and epitaxial TiN on MgO (001) systems were studied. It was found that the deformation in the harder films was controlled by the deformation in

  5. Transmission electron microscope sample holder with optical features

    DOEpatents

    Milas, Mirko; Zhu, Yimei; Rameau, Jonathan David

    2012-03-27

    A sample holder for holding a sample to be observed for research purposes, particularly in a transmission electron microscope (TEM), generally includes an external alignment part for directing a light beam in a predetermined beam direction, a sample holder body in optical communication with the external alignment part and a sample support member disposed at a distal end of the sample holder body opposite the external alignment part for holding a sample to be analyzed. The sample holder body defines an internal conduit for the light beam and the sample support member includes a light beam positioner for directing the light beam between the sample holder body and the sample held by the sample support member.

  6. [Multiple transmission electron microscopic image stitching based on sift features].

    PubMed

    Li, Mu; Lu, Yanmeng; Han, Shuaihu; Wu, Zhuobin; Chen, Jiajing; Liu, Zhexing; Cao, Lei

    2015-08-01

    We proposed a new stitching method based on sift features to obtain an enlarged view of transmission electron microscopic (TEM) images with a high resolution. The sift features were extracted from the images, which were then combined with fitted polynomial correction field to correct the images, followed by image alignment based on the sift features. The image seams at the junction were finally removed by Poisson image editing to achieve seamless stitching, which was validated on 60 local glomerular TEM images with an image alignment error of 62.5 to 187.5 nm. Compared with 3 other stitching methods, the proposed method could effectively reduce image deformation and avoid artifacts to facilitate renal biopsy pathological diagnosis. PMID:26403733

  7. Dynamics of a nanodroplet under a transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Leong, Fong Yew; Mirsaidov, Utkur M.; Matsudaira, Paul; Mahadevan, L.

    2014-01-01

    We investigate the cyclical stick-slip motion of water nanodroplets on a hydrophilic substrate viewed with and stimulated by a transmission electron microscope. Using a continuum long wave theory, we show how the electrostatic stress imposed by non-uniform charge distribution causes a pinned convex drop to deform into a toroidal shape, with the shape characterized by the competition between the electrostatic stress and the surface tension of the drop, as well as the charge density distribution which follows a Poisson equation. A horizontal gradient in the charge density creates a lateral driving force, which when sufficiently large, overcomes the pinning induced by surface heterogeneities in the substrate disjoining pressure, causing the drop to slide on the substrate via a cyclical stick-slip motion. Our model predicts step-like dynamics in drop displacement and surface area jumps, qualitatively consistent with experimental observations.

  8. Dynamics of a nanodroplet under a transmission electron microscope

    SciTech Connect

    Leong, Fong Yew; Mirsaidov, Utkur M.; Matsudaira, Paul; Mahadevan, L.

    2014-01-15

    We investigate the cyclical stick-slip motion of water nanodroplets on a hydrophilic substrate viewed with and stimulated by a transmission electron microscope. Using a continuum long wave theory, we show how the electrostatic stress imposed by non-uniform charge distribution causes a pinned convex drop to deform into a toroidal shape, with the shape characterized by the competition between the electrostatic stress and the surface tension of the drop, as well as the charge density distribution which follows a Poisson equation. A horizontal gradient in the charge density creates a lateral driving force, which when sufficiently large, overcomes the pinning induced by surface heterogeneities in the substrate disjoining pressure, causing the drop to slide on the substrate via a cyclical stick-slip motion. Our model predicts step-like dynamics in drop displacement and surface area jumps, qualitatively consistent with experimental observations.

  9. ELECTRON MICROSCOPIC OBSERVATIONS ON ACTINOPHAGES FOR STREPTOMYCES VENEZUELAE.

    PubMed

    PAINTER, B G; BRADLEY, S G

    1965-01-01

    Painter, B. G. (University of Minnesota, Minneapolis), and S. G. Bradley. Electron microscopic observations on actinophages for Streptomyces venezuelae. J. Bacteriol. 89:240-244. 1965.-Actinophages MSP2 and MSP8 were treated with various chemical agents to determine the phages' substructure. Normal MSP2 and MSP8, shadowed with uranium, or negatively stained with uranyl acetate or phosphotungstic acid, were tadpole-shaped. The average overall length of MSP2 was 245 mmu, and of MSP8, 206 mmu. The head width of both phages was approximately 58 mmu; the tail of MSP2 was 161 mmu long, and of MSP8, 137 mmu. Treatment of MSP2 and MSP8 with 7.5 m ammonium hydroxide at 56 C or 8 m urea at room temperature released some of the head contents, and revealed substructures in both the heads and the tails. The tails of phages treated with 7.5 m mercaptoethanol were destroyed.

  10. Structural Fingerprinting of Nanocrystals in the Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Rouvimov, Sergei; Plachinda, Pavel; Moeck, Peter

    2010-03-01

    Three novel strategies for the structurally identification of nanocrystals in a transmission electron microscope are presented. Either a single high-resolution transmission electron microscopy image [1] or a single precession electron diffractogram (PED) [2] may be employed. PEDs from fine-grained crystal powders may also be utilized. Automation of the former two strategies is in progress and shall lead to statistically significant results on ensembles of nanocrystals. Open-access databases such as the Crystallography Open Database which provides more than 81,500 crystal structure data sets [3] or its mainly inorganic and educational subsets [4] may be utilized. [1] http://www.scientificjournals.org/journals 2007/j/of/dissertation.htm [2] P. Moeck and S. Rouvimov, in: {Drugs and the Pharmaceutical Sciences}, Vol. 191, 2009, 270-313 [3] http://cod.ibt.lt, http://www.crystallography.net, http://cod.ensicaen.fr, http://nanocrystallography.org, http://nanocrystallography.net, http://journals.iucr.org/j/issues/2009/04/00/kk5039/kk5039.pdf [4] http://nanocrystallography.research.pdx.edu/CIF-searchable

  11. A new in vitro model of Entamoeba histolytica adhesion, using the human colon carcinoma cell line Caco-2: scanning electron microscopic study.

    PubMed Central

    Rigothier, M C; Coconnier, M H; Servin, A L; Gayral, P

    1991-01-01

    The human colon carcinoma cell line Caco-2, which is widely used to study the adhesion and cytotoxicity of enterobacteria, was used to investigate the adhesion of the trophozoites of Entamoeba histolytica. We observed a high percentage of adhesion of amoebae to Caco-2 cells. Scanning electron microscopy showed that amoebial membrane structures were involved in adhesion and the cytolytic action. These differentiated cells should prove to be a useful model system for investigation of the pathogenic action of amoebae. Images PMID:1937772

  12. Large area fabrication of plasmonic nanoparticle grating structure by conventional scanning electron microscope

    SciTech Connect

    Sudheer, Tiwari, P.; Rai, V. N.; Srivastava, A. K.; Mukharjee, C.

    2015-06-24

    Plasmonic nanoparticle grating (PNG) structure of different periods has been fabricated by electron beam lithography using silver halide based transmission electron microscope film as a substrate. Conventional scanning electron microscope is used as a fabrication tool for electron beam lithography. Optical microscope and energy dispersive spectroscopy (EDS) have been used for its morphological and elemental characterization. Optical characterization is performed by UV-Vis absorption spectroscopic technique.

  13. Electron microscope and x-ray diffraction studies of the effects of dehydration on the structure of nerve myelin. II. Optic nerve.

    PubMed

    FINEAN, J B

    1960-09-01

    The dehydration of rat optic nerve has been studied by allowing specimens to become partially or fully dried before fixation and preparation for electron microscopy. A correlation is established between electron micrographs of the myelin sheath and corresponding small-angle x-ray diffraction patterns. The modifications of the optic nerve myelin layers during drying were very similar to those described in more detail for the myelin of frog sciatic nerve. The most striking difference was that the system of fine layers characteristic of the fully dried myelin was much more extensive in the case of the optic nerve, and the layer thickness was significantly greater than the corresponding layer in the frog sciatic nerve preparation. The significance of these correlations is discussed.

  14. Scanning and transmission electron microscopic study of adherence of Escherichia coli O103 enteropathogenic and/or enterohemorrhagic strain GV in enteric infection in rabbits.

    PubMed Central

    Licois, D; Reynaud, A; Federighi, M; Gaillard-Martinie, B; Guillot, J F; Joly, B

    1991-01-01

    The GV strain (serotype O103:H2:K-), originally isolated from a diarrheic rabbit, is an enteropathogenic Escherichia coli strain that produces diarrhea without synthesizing the classical enterotoxins and that is not invasive. This strain is characterized by a 117-kb plasmid (pREC-1). Histological study of the gut by scanning electron microscopy and transmission electron microscopy was performed on the GV strain, on a derivative strain cured of pREC-1, and on transconjugants obtained by transfer of pREC-1 to nonpathogenic strains E. coli K-12 and 6100, not belonging to the O103 serogroup. The GV strain adhered to the epithelial cells of the ileum and large intestine, whereas the cured GV strain did not. Transfer of plasmid pREC-1 to E. coli K-12 or 6100 allowed the bacteria to attach to the intestinal mucosa in the same manner as that of the wild-type GV strain. Thus, pREC-1 seems to play an important role in attachment to and colonization of the intestinal tract of rabbits by E. coli serogroup O103. Scanning electron microscopy showed numerous bacteria attached together and closely associated with intestinal villi. Transmission electron microscopy revealed effacing lesions characteristic of enteropathogenic E. coli strains: effacing of microvilli and cuplike projections (pedestal formations) associated with an acute inflammatory and hemorrhagic response. In contrast with the results reported for rabbit pathogenic O15 strains, it appeared that the Peyer's patches were not involved in the early stages of infection with the O103 GV strain. This strain may represent a model for the study of the virulence and pathogenic effects of enteropathogenic and enterohemorrhagic E. coli strains. Images PMID:1894377

  15. A study on amitosis of the nucleus of the mammalian cell. I. A study under the light and transmission electron microscope.

    PubMed

    Chen, Y Q; Wan, B K

    1986-01-01

    The experiments were conducted on two species of experimental animals: mice and rats. The mice were poisoned by CCl4, whereas the rats had a hepatectomy in order to remove a larger part of the left lobe of the liver. 5 samples of human liver cancer tissue were examined by routine methods. The phenomena of amitosis were studied. In addition to more features of amitosis, many intranuclear structures characteristic of amitosis were found in the carcinoma tissue. The authors propose to divide the nuclear amitosis process into 4 stages and try to design a diagrammatic picture of amitosis in order to illustrate that also by amitosis chromatin can be reproduced and equally distributed to the daughter cells, so that the continuity and precision of gene threads is guaranteed in the daughter cells. The study discusses the functional significance of nuclear amitosis.

  16. Visualization of macromolecular complexes using cryo-electron microscopy with FEI Tecnai transmission electron microscopes

    PubMed Central

    Grassucci, Robert A; Taylor, Derek; Frank, Joachim

    2009-01-01

    This protocol details the steps used for visualizing the frozen-hydrated grids as prepared following the accompanying protocol entitled ‘Preparation of macromolecular complexes for visualization using cryo-electron microscopy.’ This protocol describes how to transfer the grid to the microscope using a standard cryo-transfer holder or, alternatively, using a cryo-cartridge loading system, and how to collect low-dose data using an FEI Tecnai transmission electron microscope. This protocol also summarizes and compares the various options that are available in data collection for three-dimensional (3D) single-particle reconstruction. These options include microscope settings, choice of detectors and data collection strategies both in situations where a 3D reference is available and in the absence of such a reference (random-conical and common lines). PMID:18274535

  17. Ultra low-K shrinkage behavior when under electron beam in a scanning electron microscope

    SciTech Connect

    Lorut, F.; Imbert, G.; Roggero, A.

    2013-08-28

    In this paper, we investigate the tendency of porous low-K dielectrics (also named Ultra Low-K, ULK) behavior to shrink when exposed to the electron beam of a scanning electron microscope. Various experimental electron beam conditions have been used for irradiating ULK thin films, and the resulting shrinkage has been measured through use of an atomic force microscope tool. We report the shrinkage to be a fast, cumulative, and dose dependent effect. Correlation of the shrinkage with incident electron beam energy loss has also been evidenced. The chemical modification of the ULK films within the interaction volume has been demonstrated, with a densification of the layer and a loss of carbon and hydrogen elements being observed.

  18. Effects of Propyithiouracil (PTU) Administration on the Synthesis and Secretion of Thyroglobulin in the Rat Thyroid Gland: A Quantitative Immuno-electron Microscopic Study Using Immunogold Technique.

    PubMed

    Yi, Xue; Yamamoto, Koichi; Shu, Lu; Katoh, Ryohei; Kawaoi, Akira

    1997-01-01

    To clarify the effects of an antithyroid drug on the kinetics of thyroglobulin synthesis, secretion, and reabsorption in the thyroid follicles, propylthiouracil (PTU) was administered to rats and the thyroid glands were examined by a refined post-embedding immunogold technique during and after withdrawal of PTU. Seven-wk-old male Wistar rats were administered with S mg of PTU/d through a gastric tube, and sacrificed at 1 and 2 wk of administration and at 1, 2, and 3 d, and 1, 2, 3, and 4 wk, after discontinuation. The administration of PTU caused a remarkable dilatation of the rER and Golgi apparatus, but these areas gradually recovered after withdrawal of PTU. During the experiment, no significant change in the density of thyroglobulin (Tg) was observed except for a transient increase immediately after withdrawal of PTU. The expression of Tg on subapical vesicles (SV) and follicular colloid took a relatively parallel course; increasing during administration of PTU and decreasing with a transient peak immediately after treatment was discontinued. In contrast to the remarkable changes in the morphology of compartments involved in Tg synthesis, the development of colloid droplets and formation of secondary lysosomes were suppressed during and after discontinuing administration of PTU. However, the basic pattern of the gradient of Tg density among the cellular compartments was essentially retained in the experimental group. Thus the present immunoelectron-microscopic study provided evidence that administration of PTU stimulates the synthesis and secretion of Tg in the follicular epithelium in vivo, and, also, suppresses reabsorption and degradation of Tg. Further, it was speculated that the density gradient of Tg among the compartments involved in Tg synthesis, secretion and storage is regulated by an unknown constitutive mechanism and not by the thyroid-stimulating hormone (TSH)-TSH receptor-mediated system.

  19. Atomic imaging using secondary electrons in a scanning transmission electron microscope: experimental observations and possible mechanisms.

    PubMed

    Inada, H; Su, D; Egerton, R F; Konno, M; Wu, L; Ciston, J; Wall, J; Zhu, Y

    2011-06-01

    We report detailed investigation of high-resolution imaging using secondary electrons (SE) with a sub-nanometer probe in an aberration-corrected transmission electron microscope, Hitachi HD2700C. This instrument also allows us to acquire the corresponding annular dark-field (ADF) images both simultaneously and separately. We demonstrate that atomic SE imaging is achievable for a wide range of elements, from uranium to carbon. Using the ADF images as a reference, we studied the SE image intensity and contrast as functions of applied bias, atomic number, crystal tilt, and thickness to shed light on the origin of the unexpected ultrahigh resolution in SE imaging. We have also demonstrated that the SE signal is sensitive to the terminating species at a crystal surface. A possible mechanism for atomic-scale SE imaging is proposed. The ability to image both the surface and bulk of a sample at atomic-scale is unprecedented, and can have important applications in the field of electron microscopy and materials characterization.

  20. In situ formation of bismuth nanoparticles through electron-beam irradiation in a transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Sepulveda-Guzman, S.; Elizondo-Villarreal, N.; Ferrer, D.; Torres-Castro, A.; Gao, X.; Zhou, J. P.; Jose-Yacaman, M.

    2007-08-01

    In this work, bismuth nanoparticles were synthesized when a precursor, sodium bismuthate, was exposed to an electron beam at room temperature in a transmission electron microscope (TEM). The irradiation effects were investigated in situ using selected-area electron diffraction, high-resolution transmission electron microscopy and x-ray energy dispersive spectroscopy. After the electron irradiation, bismuth nanoparticles with a rhombohedral structure and diameter of 6 nm were observed. The average particle size increased with the irradiation time. The electron-induced reduction is attributed to the desorption of oxygen ions. This method offers a one-step route to synthesize bismuth nanoparticles using electron irradiation, and the particle size can be controlled by the irradiation time.

  1. In Situ Microstructural Control and Mechanical Testing Inside the Transmission Electron Microscope at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Wang, Baoming; Haque, M. A.

    2015-08-01

    With atomic-scale imaging and analytical capabilities such as electron diffraction and energy-loss spectroscopy, the transmission electron microscope has allowed access to the internal microstructure of materials like no other microscopy. It has been mostly a passive or post-mortem analysis tool, but that trend is changing with in situ straining, heating and electrical biasing. In this study, we design and demonstrate a multi-functional microchip that integrates actuators, sensors, heaters and electrodes with freestanding electron transparent specimens. In addition to mechanical testing at elevated temperatures, the chip can actively control microstructures (grain growth and phase change) of the specimen material. Using nano-crystalline aluminum, nickel and zirconium as specimen materials, we demonstrate these novel capabilities inside the microscope. Our approach of active microstructural control and quantitative testing with real-time visualization can influence mechanistic modeling by providing direct and accurate evidence of the fundamental mechanisms behind materials behavior.

  2. Semiautomatic classification of cementitious materials using scanning electron microscope images

    NASA Astrophysics Data System (ADS)

    Drumetz, Lucas; Mura, Mauro Dalla; Meulenyzer, Samuel; Lombard, Sébastien; Chanussot, Jocelyn

    2015-11-01

    Segmentation and classification are prolific research topics in the image processing community. These topics have been increasingly used in the context of analysis of cementitious materials on images acquired with a scanning electron microscope. Indeed, there is a need to be able to detect and to quantify the materials present in a cement paste in order to follow the chemical reactions occurring in the material even days after the solidification. We propose a new approach for segmentation and classification of cementitious materials based on the denoising of the data with a block-matching three-dimensional (3-D) algorithm, binary partition tree (BPT) segmentation, support vector machines (SVM) classification, and interactivity with the user. The BPT provides a hierarchical representation of the spatial regions of the data, allowing a segmentation to be selected among the admissible partitions of the image. SVMs are used to obtain a classification map of the image. This approach combines state-of-the-art image processing tools with user interactivity to allow a better segmentation to be performed, or to help the classifier discriminate the classes better. We show that the proposed approach outperforms a previous method when applied to synthetic data and several real datasets coming from cement samples, both qualitatively with visual examination and quantitatively with the comparison of experimental results with theoretical ones.

  3. The effects of rearing light level and duration differences on the optic nerve, brain, and associated structures in developing zebrafish larvae: a light and transmission electron microscope study.

    PubMed

    Chapman, George B; Tarboush, Rania; Connaughton, Victoria P

    2012-03-01

    The ultrastructure of the optic nerve, brain, and some associated structures of larval zebrafish, grown under three different light regimens were studied. Fish grown under cyclic light (control), constant dark (CD), and constant light (CL) were studied for 4 and 8 days postfertilization (dpf). We also studied the control and CD fish at 15 dpf. The brains of the control and CL fish were larger at 4 dpf than at 8 dpf. In all 4 dpf fish, the brain occupied the entire expanse between the two retinas and the optic nerve extended the shortest distance between the retina and the brain. The 15 dpf zebrafish had the smallest brain size. Groups of skeletal muscle cells associated with the optic nerves became visible in all older larvae. In the 15 dpf larvae, bulges and dilations in the optic nerve occurred as it reached the brain and optic chiasms occurred proximal to the brain. Electron microscopy yielded information about myelinated and unmyelinated axons in the optic nerve, the dimensions of neurotubules, neurofilaments, and myofilaments, including a unique variation in actin myofilaments, and a confirmation of reported myosin myofilament changes (but with dimensions). We also describe the ultrastructure of a sheath-like structure that is confluent over the optic nerve and the brain, which has not been described before in zebrafish. Also presented are images of associated fibroblasts, epithelial cells lining the mouth, cartilage plates, blood vessels, nerve bundles, and skeletal muscle cells, most of which have not been previously described in the literature.

  4. Is the sperm-binding capability of the zona pellucida linked to its surface structure? A scanning electron microscopic study of human in vitro fertilization.

    PubMed

    Familiari, G; Nottola, S A; Micara, G; Aragona, C; Motta, P M

    1988-06-01

    The structure of the zona pellucida and the early interactions between human oocytes and spermatozoa were investigated in an in vitro fertilization program. Thirty-five mature (preovulatory) oocytes, 10 immature oocytes lacking a germinal vesicle, and 11 atretic oocytes which had not undergone fertilization at 10-20 hr after insemination were studied by light and scanning electron microscopy. Observed through employment of these techniques, the zona pellucida showed two basically different patterns: a mesh-like, spongy structure having wide and/or close meshes; and a compact, smooth surface. The smooth-surfaced zona was most commonly seen in the cultured oocytes belonging to the immature and atretic groups. These observations seem to show that the spongy appearance of the zona pellucida is related mainly to oocyte development and maturity. In this study, greater numbers of penetrating spermatozoa were noted on oocytes showing the mesh-like zona, in contrast to the presence of a few sperm flattened against its surface or the frank absence of sperm associated with oocytes having the more compact, smooth zona. It is likely that the condensation of the outer aspect of the zona pellucida causes a disorientation of sperm-binding sites, which would probably result in markedly reduced binding and penetration capacity with spermatozoa. These changes might ultimately lead to impairment of in vitro oocyte fertilizability.

  5. Comparative Scanning Electron Microscopic Study of the Marginal Adaptation of Four Root-End Filling Materials in Presence and Absence of Blood

    PubMed Central

    Bolhari, Behnam; Ashofteh Yazdi, Kazem; Sharifi, Farnood; Pirmoazen, Salma

    2015-01-01

    Objectives: The aim of this study was to evaluate marginal adaptation of mineral trioxide aggregate (MTA), calcium enriched mixture (CEM) cement, Biodentine and BioAggregate in presence of normal saline and human blood. Materials and Methods: In this in-vitro experimental study, 80 extracted single-rooted human teeth were instrumented and filled with gutta-percha. After resecting the root-end, apical cavity preparation was done and the teeth were randomly divided into 4 groups (N=20)(a total of 8 subgroups). Root-end filling materials were placed in 3mm root-end cavities prepared ultrasonically. Half the specimens in each group were exposed to normal saline and the other half to fresh whole human blood. After 4 days, epoxy resin replicas of the apical portion of samples were fabricated and scanning electron microscopy (SEM) analysis was performed to find gaps in the adaptation of the root-end filling materials at their interface with dentin. The Kruskal-Wallis and Mann-Whitney tests were used for statistical analysis of data with P<0.05 as the limit of significance. Results: There were no significant differences in marginal adaptation of the 8 tested groups (P>0.05). Conclusion: Based on the results, blood contamination does not affect the marginal adaptation of MTA, CEM cement, Biodentine or BioAggregate. PMID:26622276

  6. Comparative study viruses with computer-aided phase microscope AIRYSCAN

    NASA Astrophysics Data System (ADS)

    Tychinsky, Vladimir P.; Koufal, Georgy E.; Perevedentseva, Elena V.; Vyshenskaia, Tatiana V.

    1996-12-01

    Traditionally viruses are studied with scanning electron microscopy (SEM) after complicated procedure of sample preparation without the possibility to study it under natural conditions. We obtained images of viruses (Vaccinia virus, Rotavirus) and rickettsias (Rickettsia provazekii, Coxiella burnetti) in native state with computer-aided phase microscope airyscan -- the interference microscope of Linnik layout with phase modulation of the reference wave with dissector image tube as coordinate-sensitive photodetector and computer processing of phase image. A light source was the He-Ne laser. The main result is coincidence of dimensions and shape of phase images with available information concerning their morphology obtained with SEM and other methods. The fine structure of surface and nuclei is observed. This method may be applied for virus recognition and express identification, investigation of virus structure and the analysis of cell-virus interaction.

  7. Serotonin-immunoreactive neurones in the visual system of the praying mantis: an immunohistochemical, confocal laser scanning and electron microscopic study.

    PubMed

    Leitinger, G; Pabst, M A; Kral, K

    1999-03-27

    The distribution, number, and morphology of serotonin-immunoreactive (5-HTi) neurones in the optic lobe of the praying mantis Tenodera sinensis were studied using conventional microscopy and confocal laser scanning microscopy. Five or six 5-HTi neurones connect the lobula complex with the medulla, and at least 50 5-HTi neurones appear to be confined to the medulla. In addition, a few large 5-HTi processes from the protocerebrum supply the lobula complex, and two large 5-HTi processes from the protocerebrum ramify in the medulla and lamina, where they show wide field arborisations. In order to provide a basis for understanding the action of serotonin in the lamina, the ultrastructure of its 5-HTi terminals was examined by conventional and immunohistochemical electron microscopy. The 5-HTi profiles were filled with dense core vesicles and made synapses. Output synapses from 5-HTi profiles outnumbered inputs by about 3 to 1. The terminals of the 5-HTi neurones were in close contact with cells of various types, including large monopolar cells, but close apposition to photoreceptor terminals was rare, and no synapses were found between 5-HTi terminals and photoreceptor terminals. PMID:10095007

  8. Light and scanning electron microscopic study of the tongue in the estuarine dolphin (Sotalia guianensis van Bénéden, 1864).

    PubMed

    Guimarães, Juliana Plácido; Mari, Renata de Britto; Marigo, Juliana; Rosas, Fernando César Weber; Watanabe, Ii-Sei

    2011-08-01

    The importance of the tongue during feeding, and the limited information on the tongue of most aquatic mammals led us to investigate its morphological aspects in sexually immature and mature Sotalia guianensis. Six tongues were measured and photo-documented after their removal from the oral cavity. The samples were divided into rostral, middle, and caudal regions, and examined using light microscopy and scanning electron microscopy (S.E.M.). Sotalia guianensis tongue presented lateral grooves from the apex to the middle portion, while the anterolateral region presented marginal papillae. Histological characteristics revealed the presence of a keratinized stratified epithelium, salivary glands in the middle and caudal portions of the tongue, and filiform papillae in the caudal region. S.E.M. images revealed the presence of filiform papillae and ducts of salivary glands in the middle and caudal portions of the tongue. We can conclude that the characteristics found in this study may reflect an adaptation to changes in diet after weaning. PMID:21801004

  9. Production of otoconia in the endolymphatic sac in the Japanese red-bellied newt, Cynops pyrrhogaster: light and transmission electron microscopic study

    NASA Technical Reports Server (NTRS)

    Gao, W.; Wiederhold, M. L.; Hejl, R.

    1998-01-01

    The formation of otoconia in the endolymphatic sac (ES) of the larval newt, Cynops pyrrhogaster, has been studied by light and transmission electron microscopy. Some of the epithelial cells of the ES contain an abundance of swollen vesicles, Golgi complexes, rough endoplasmic reticula and ribosomes at the late larval stages 50 and 51, approximately 26-30 days after eggs are laid. Five days later, at stage 52, crystals are present in the vacuoles between the epithelial cells. Serial sections indicate that these vacuoles actually form small canals which lie in the wall and join the lumen of the ES. Reconstruction of the ES shows that several canals are contained in the ES wall. At stage 56, about 72 days after eggs are laid, a large number of otoconia are present in the ES lumen, while the otoconia disappear from the canals. It appears that the otoconia are first produced in the canals and then released to the lumen. Some epithelial cells of the ES are thought to expel the organic and inorganic material to the canals to form the otoconia in situ. The process of formation of the otoconia in the ES is discussed.

  10. A Transmission Electron Microscope Investigation of Space Weathering Effects in Hayabusa Samples

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Berger, Eve L.

    2014-01-01

    The Hayabusa mission to asteroid 25143 Itokawa successfully returned the first direct samples of the regolith from the surface of an asteroid. The Hayabusa samples thus present a special opportunity to directly investigate the evolution of asteroidal surfaces, from the development of the regolith to the study of the more complex effects of space weathering. Here we describe the mineralogy, microstructure and composition of three Hayabusa mission particles using transmission electron microscope (TEM) techniques

  11. Application of an ultrahigh-resolution scanning electron microscope (UHS-T1) to biological specimens.

    PubMed

    Tanaka, K; Mitsushima, A; Kashima, Y; Nakadera, T; Osatake, H

    1989-06-01

    In 1985 we developed an ultrahigh-resolution scanning electron microscope with a resolution of 0.5 nm. It is equipped with a field emission gun and an objective lens with a very short focal length. In this study we report a survey of some different preparation techniques and biological specimens using the new scanning electron microscope. Intracellular structures such as cell organelles were observed surprisingly sharper than those observed by ordinary scanning electron microscopes. However, at magnifications over 250,000 x, platinum particles could be discerned as scattered pebbles on the surface of all structures in coated materials. Using an uncoated but conductively stained specimen, we successfully observed ribosomes on a rough endoplasmic reticulum at a direct magnification of 1 million. In these images some protrusions were recognized on the ribosomes. Ferritin and immunoglobulin G were used as samples of biological macromolecules. These samples were observed without metal coating and conductive staining. The ferritin particles appeared as rounded bodies without any substructure on the surface and immunoglobulin G as complexes of three-unit bodies. In the latter the central body might correspond to the Fc fragment and two side ones to Fab fragments. We assume that ultrahigh-resolution scanning electron microscopy is an effective means for observation of the cell fine structures and biological macromolecules. It will open a new research field in biomedicine.

  12. Analytical study of microsomes and isolated subcellular membranes from rat liver. VI. Electron microscope examination of microsomes for cytochrome b5 by means of a ferritin-labeled antibody.

    PubMed

    Remacle, J; Fowler, S; Beaufay, H; Amarcostesec, A; Berthet, J

    1976-11-01

    The distribution of cytochrome b5 in rat liver microsomes, and in two microsomal subfractions isolated by density equilibration in a linear sucrose gradient, was studied under the electron microscope by means of a ferritin-labeled hybrid anti-cytochrome b5/anti-ferritin antibody. Results of this study show that cytochrome b5 is present in essentially all microsomal vesicles derived from endoplasmic reticulum (ER), whether rough or smooth. Thus, the dissociation of ER constituents into two groups (b and c), achieved by subfractionating microsomes by isopycnic centrifugation (Beaufay, H., A. Amar-Costesec, D. Thines-Sempoux, M. Wibo, M. Robbi, and J. Berthet. 1974. J. Cell Biol. 61:213-231), does not reflect the association of each group with distinct microsomal particles but reflects rather an enzymatic heterogeneity of the ER: the ratio of group c to group b enzymes increasing with the density and ribosome load of the particles.

  13. The effects of swimming exercise and supraphysiological doses of nandrolone decanoate on the testis in adult male rats: a transmission electron microscope study.

    PubMed

    Naraghi, M A; Abolhasani, F; Kashani, I; Anarkooli, I J; Hemadi, M; Azami, A; Barbarestani, M; Aitken, R J; Shokri, S

    2010-08-01

    Anabolic-androgenic steroids (AAS) are used in high doses by athletes to improve athletic ability, physical appearance, and muscle mass. Unfortunately, the abuse of these agents has significantly increased. It has been established that exercise and high doses of AAS may influence the hypothalamic-pituitary gonadal (H-P-G) axis, which can in turn affect the ultrastructure of the testes. However, the effect of the combination of exercise and high doses of AAS on the ultrastructure of the testes is not known. This study was undertaken in order to examine the combination effects of swimming exercise and supraphysiological doses of nandrolone decanoate on the ultrastructural changes in rat testes. Five groups of male Wistar strain albino rats were treated as follows for 8 weeks: solvent of nandrolone decanoate (peanut oil) as a vehicle (sham); nandrolone decanoate (ND) (10 mg/kg/week) - ND; exercise (1 h/day, 5 days a week) - exercise; ND (10 mg/kg/week) and exercise (1 h/day, 5 days a week) - ND-EX; and sedentary control without any injection or exercise - control. Ultrastructural changes in the rat testes were characterised by transmission electron microscopy. The number and size of Leydig cells were considerably decreased in the interstitial space in the experimental rats. The increased thickness and irregular wavy multilaminar appearance of basement membrane in the treated animals, especially in the ND-EX group, are associated with well developed myoid cells. Cytoplasm vacuolisation, vesicular-like crista of the mitochondria, numerous lipid droplets, and lysosome and phagolysosome in Sertoli cells were significantly observed in the experimental groups. Several apoptotic germ cells were considerably observed in the experimental rats (p ≤ 0.05). Exercise training seems to increase the extent of ultrastructural changes caused by supraphysiological doses of ND in rats, which in turn may affect fertility.

  14. The Design and Construction of a Simple Transmission Electron Microscope for Educational Purposes.

    ERIC Educational Resources Information Center

    Hearsey, Paul K.

    This document presents a model for a simple transmission electron microscope for educational purposes. This microscope could demonstrate thermonic emission, particle acceleration, electron deflection, and flourescence. It is designed to be used in high school science courses, particularly physics, taking into account the size, weight, complexity…

  15. Transmission electron microscopic characterization of hypersensitive human radicular dentin

    SciTech Connect

    Yoshiyama, M.; Noiri, Y.; Ozaki, K.; Uchida, A.; Ishikawa, Y.; Ishida, H. )

    1990-06-01

    Transmission electron microscopy (TEM) and x-ray microanalysis (XMA) were used for the study of the ultrastructure of the lumens of dentinal tubules in superficial layers of dentin specimens obtained by use of a new biopsy technique from both hypersensitive and naturally desensitized areas of exposed root surfaces, in vivo. The TEM images showed clearly that the lumens of most of the tubules were occluded with mineral crystals in naturally desensitized areas, but such lumens were empty and surrounded with peritubular and intertubular dentin in hypersensitive areas. Moreover, electron-dense structures that lined peritubular dentin were observed in the empty lumens of dentinal tubules.

  16. Transmission electron microscopic examination of phosphoric acid fuel cell components

    NASA Technical Reports Server (NTRS)

    Pebler, A.

    1986-01-01

    Transmission electron microscopy (TEM) was used to physically characterize tested and untested phosphoric acid fuel cell (PAFC) components. Those examined included carbon-supported platinum catalysts, carbon backing paper, and Teflon-bonded catalyst layers at various stages of fabrication and after testing in pressurized PAFC's. Applicability of electron diffraction and electron energy loss spectroscopy for identifying the various phases was explored. The discussion focuses on the morphology and size distribution of platinum, the morphology and structural aspects of Teflon in catalyst layers, and the structural evidence of carbon corrosion. Reference is made to other physical characterization techniques where appropriate. A qualitative model of the catalyst layer that emerged from the TEM studies is presented.

  17. Glass for parenteral products: a surface view using the scanning electron microscope.

    PubMed

    Roseman, T J; Brown, J A; Scothorn, W W

    1976-01-01

    The scanning electron microscope was utilized to explore the internal surface of glass ampuls and vials used in parenteral products. The surface topography of USP Type I borosilicate glass containers was viewed after exposure to "sulfur," ammonium bifluoride, and sulfuric acid treatments. The scanning electron micrographs showed startling differences in the appearance of the surface regions. "Sulfur treatment" of ampuls was associated with a pitting of the surface and the presence of sodium sulfate crystals. The sulfur treatment of vials altered the glass surface in a characteristically different manner. The dissimilarity between the surface appearances was attributed to the method of sulfur treatment. Ampuls exposed to sulfuric acid solutions at room temperature did not show the pitting associated with the sulfur treatment. Scanning electron micrographs of ammonium bifluoride-treated ampuls showed a relief effect, suggesting that the glass was affected by the bifluoride solution but that sufficient stripping of the surface layer did not occur to remove the pits associated with the sulfur treatment. Flakes emanating from the glass were identified with the aid of the electron microprobe. Scanning electron micrographs showed that these vitreous flakes resulted from a delamination of a thin layer of the glass surface. It is concluded that the scanning electron microscope, in conjunction with other analytical techniques, is a valuable tool in assessing the quality of glass used for parenteral products. The techniques studied should be of particular importance to the pharmaceutical industry where efforts are being made to reduce the levels of particulate matter in parenteral dosage forms.

  18. Sarcocystis acanthocolubri sp. n. infecting three lizard species of the genus Acanthodactylus and the problem of host specificity. Light and electron microscopic study.

    PubMed

    Morsy, Kareem; Bashtar, Abdel-Rahman; Abdel-Ghaffar, Fathy; Mehlhorn, Heinz; Al Quraishy, Saleh; Al-Ghamdi, Ali; Koura, Eglal; Maher, Sherein

    2012-01-01

    In the present investigation, macroscopic sarcocysts of Sarcocystis acanthocolubri were observed in muscles of 42 (4.3%) out of 975 Acanthodactylus sp. lizards collected from different geographical areas in Egypt. The infection rate was 6.4% in Acanthodactylus boskianus, 2.1% in Acanthodactylus sculentus, and 5% in Acanthodactylus paradalis. The highest infection rate was recorded in the lizards captured from Baltem (10% in A. boskianus and 8% in A. paradalis). The infection rate was usually higher in females (7.4%) than in males (3.8%). Moreover, the highest infection rate was recorded in summer (7.53%), autumn (3.57%), and spring (3.11%), and the lowest was recorded in winter (0.91%). Also, old animals had higher infection rates (10.8%) than young ones (0-2.7%). Macrocysts measured 0.95 × 10.12 mm. Both macroscopic and microscopic sarcocysts were enclosed only by a primary cyst wall, which had many finger-like, stalkless, and non-branched protrusions giving it a striated appearance. The primary cyst wall measured 3.9 μm. A dark granulated ground substance was found directly underneath the protrusions and is extended interiorly dividing the cyst cavity into many compartments containing the parasites (metrocytes and merozoites). Metrocytes were found directly under the ground substance and usually multiply asexually by endodyogeny producing two merozoites from each metrocyte. Both metrocytes and merozoites had the apical complex structures characteristic to the genus Sarcocystis. Transmission experiments with three snake species indicated that the snake Spalerosophis diadema is the proper final host belonging to the family Colubridae. The prepatent period was 16 days, while the patent period was 35 days. The results obtained from the present investigation revealed that this is a new species which was named Sarcocystis acanthocolubri. PMID:21710348

  19. Development of a classification system for extrinsic hair damage: standard grading of electron microscopic findings of damaged hairs.

    PubMed

    Kim, Youn-Duk; Jeon, Soo-Young; Ji, Jae Hong; Lee, Won-Soo

    2010-07-01

    Human hairs experience damage and restoration processes consistently because of various external and internal factors. To analyze degrees of hair damage, morphological studies based on electron microscopy (EM), and biochemical studies based on protein and lipid analysis have been proposed and are widely used. Among them, morphological analysis through EM is a fundamental method in understanding the degree of damage and restoration. EM has been very useful in assessing extrinsic and intrinsic damage of hair and various pathological alopecias and also in estimating the efficacy of various kinds of products related to hair care. However, morphological studies have some limitations because they have been described using varying terms and subjective descriptions by different researchers. To establish an objective classification of damaged hair using uniform terms and standardizations. We analyzed over 2000 scanning electron microscopic and transmission electron microscopic findings of normal and of various kinds of damaged hairs to develop a standard grading system for the damaged hairs. After reviewing the results of the electron microscopic pictures, we proposed a standard grading system based on scanning electron microscope and transmission electron microscope. We developed and proposed an easy, objective, and useful standard grading system of damaged hairs.

  20. Apparatus and methods for controlling electron microscope stages

    SciTech Connect

    Duden, Thomas

    2015-08-11

    Methods and apparatus for generating an image of a specimen with a microscope (e.g., TEM) are disclosed. In one aspect, the microscope may generally include a beam generator, a stage, a detector, and an image generator. A plurality of crystal parameters, which describe a plurality of properties of a crystal sample, are received. In a display associated with the microscope, an interactive control sphere based at least in part on the received crystal parameters and that is rotatable by a user to different sphere orientations is presented. The sphere includes a plurality of stage coordinates that correspond to a plurality of positions of the stage and a plurality of crystallographic pole coordinates that correspond to a plurality of polar orientations of the crystal sample. Movement of the sphere causes movement of the stage, wherein the stage coordinates move in conjunction with the crystallographic coordinates represented by pole positions so as to show a relationship between stage positions and the pole positions.

  1. A LIGHT AND ELECTRON MICROSCOPE STUDY OF THE MORPHOLOGICAL CHANGES INDUCED IN RAT LIVER CELLS BY THE AZO DYE 2-ME-DAB.

    PubMed

    LAFONTAINE, J G; ALLARD, C

    1964-07-01

    The cytological changes induced in rat liver cells by the aminoazo dye 2-Me-DAB have been examined by light and electron microscopy. It is observed that this non-carcinogenic compound duplicates most of the morphological alterations produced by other hepatotoxins, some of which, such as the closely related aminoazo dye 3'-Me-DAB, are potent carcinogens. These non-specific effects involve both the granular and agranular forms of the endoplasmic reticulum as well as the glycogen content of hepatic cells. The arrays of cisternal profiles of the granular reticulum in normal hepatic cells become disorganized and the dispersed cisternae often appear fragmented and irregular. Large cytoplasmic inclusions, consisting of loosely organized tubules and vesicles, are also observed which result from a hypertrophy of the agranular reticulum. The glycogen in the cells progressively decreases in amount. The most specific effect of 2-Me-DAB is to induce an increase in the number of mitochondria per cell. Many of these organelles are characterized by the presence of a median double membrane continuous with the inner limiting membrane of the mitochondrial envelope. Evidence is presented in favor of the view that this partition is directly related to the phenomenon of mitochondrial division. It was noted also in the course of the experiment that an increasing number of cells appear which stain quite intensely with methylene blue and appear denser than normal under electron microscopy. The significance of these cells is not known.

  2. In situ ion beam research in Argonne`s intermediate voltage electron microscope

    SciTech Connect

    Allen, C.W.; Ryan, E.A.

    1996-11-01

    Since Fall 1995, a state-of-the-art intermediate voltage electron microscope (IVEM) has been operational in the HVEM-Tandem Facility with in situ ion irradiation capabilities similar to those of the HVEM of the Facility. A 300 kV Hitachi H-9000NAR is interfaced to the two ion accelerators of the Facility, with a demonstrated point-to-point spatial resolution for imaging of 0.25 nm with the ion beamline attached to the microscope. The IVEM incorporates a Faraday cup system for ion dosimetry with measurement aperture 6.5 cm from the TEM specimen, which was described in Symposium A of the 1995 MRS Fall Meeting. The IVEM is now employed for a variety of in situ ion beam studies ranging from low dose ion damage experiments with GaAs, in which damage zones individual displacement cascades are observed, to implantation studies in metals, in which irradiation-induced noble gas precipitate mobility is studied in real time. In this presentation, the new instrumentation and its specifications will be described briefly, several basic concepts relating to in situ experiments in transmission electron microscopes will be summarized and examples of in situ experiments will be presented which exploit the experimental capabilities of this new user facility instrumentation.

  3. Electron microscopic analysis of rotavirus assembly-replication intermediates

    SciTech Connect

    Boudreaux, Crystal E.; Kelly, Deborah F.; McDonald, Sarah M.

    2015-03-15

    Rotaviruses (RVs) replicate their segmented, double-stranded RNA genomes in tandem with early virion assembly. In this study, we sought to gain insight into the ultrastructure of RV assembly-replication intermediates (RIs) using transmission electron microscopy (EM). Specifically, we examined a replicase-competent, subcellular fraction that contains all known RV RIs. Three never-before-seen complexes were visualized in this fraction. Using in vitro reconstitution, we showed that ~15-nm doughnut-shaped proteins in strings were nonstructural protein 2 (NSP2) bound to viral RNA transcripts. Moreover, using immunoaffinity-capture EM, we revealed that ~20-nm pebble-shaped complexes contain the viral RNA polymerase (VP1) and RNA capping enzyme (VP3). Finally, using a gel purification method, we demonstrated that ~30–70-nm electron-dense, particle-shaped complexes represent replicase-competent core RIs, containing VP1, VP3, and NSP2 as well as capsid proteins VP2 and VP6. The results of this study raise new questions about the interactions among viral proteins and RNA during the concerted assembly–replicase process. - Highlights: • Rotaviruses replicate their genomes in tandem with early virion assembly. • Little is known about rotavirus assembly-replication intermediates. • Assembly-replication intermediates were imaged using electron microscopy.

  4. Human Peripheral Lung Tumours: Light and Electron Microscopic Correlation

    PubMed Central

    Mollo, Franco; Canese, Maria G.; Campobasso, Onofrio

    1973-01-01

    Thirteen human peripheral lung tumours have been studied in both light and electron microscopy. They were classified as epidermoid carcinoma, mucus-secreting cell adenocarcinoma, and alveolar cell adenocarcinoma, the latter made up of granular pneumocytes. Alveolar cell cancer, as defined by ultrastructural features, could assume different gross histological patterns in light microscopy, and therefore electron microscopy is required for its identification. Since neither squamous nor mucous metaplasia was observed in any alveolar cell tumour, it is tentatively suggested that all peripheral lung tumours which lack these features may be derived from granular pneumocytes, irrespective of whether they appear to be adenocarcinomata or large cell carcinomata when examined by light microscopy. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11Fig. 12Fig. 13Fig. 14 PMID:4348471

  5. Damage-free vibrational spectroscopy of biological materials in the electron microscope

    DOE PAGESBeta

    Rez, Peter; Aoki, Toshihiro; March, Katia; Gur, Dvir; Krivanek, Ondrej L.; Dellby, Niklas; Lovejoy, Tracy C.; Wolf, Sharon G.; Cohen, Hagai

    2016-03-10

    Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an ‘aloof’ electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies o1 eV can be ‘safely’ investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C–H, N–H and C=O vibrational signatures with nomore » observable radiation damage. Furthermore, the technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ~10nm, simultaneously combined with imaging in the electron microscope.« less

  6. Stages in spermatogenesis of two species of caecilians, Ichthyophis tricolor and Uraeotyphlus cf. narayani (Amphibia: Gymnophiona): Light and electron microscopic study.

    PubMed

    Smita, Mathew; Oommen, Oommen V; Jancy, M George; Akbarsha, M A

    2004-07-01

    The sequential changes during spermatogenesis in the testis of two species of caecilians, Ichthyophis tricolor (Ichthyophiidae) and Uraeotyphlus cf. narayani (Uraeotyphliidae), of Western Ghats of Kerala, India, were traced using both histological techniques and transmission electron microscopy. The cell nests were assigned to stages in spermatogenesis based on the classification of van Oordt (1956, Thesis, Utrecht University). To the best of our knowledge, this is the first identification and ultrastructural description of stages in spermatogenesis in caecilians. The article illustrates not only the stages, but also the cell divisions, mitotic and meiotic, as specified. The observations indicate that, although caecilians have undergone considerable modifications in morphology and anatomy, including reproductive anatomy, in the context of a subterranean and concealed life, they appear to have conserved the typical amphibian pattern of spermatogenesis for the events of development of spermatids.

  7. Ethanol-induced chronic myopathy in the young rat: a light and electron microscopic study in type I or type II fibre-rich skeletal muscles.

    PubMed

    Salisbury, J R; Preedy, V R; Rose, P E; Deverell, M H; Peters, T J

    1992-09-01

    An investigation was made into the characteristics of an experimental chronic alcoholic myopathy in the young rat. Male Wistar rats were fed a diet for 6 weeks in which ethanol comprised 36% of total energy. Controls were pair-fed the same diet except ethanol was substituted by isoenergic glucose. Soleus (type I fibre-rich) and plantaris (type II fibre-rich) muscles were examined by light microscopy, histochemistry and electron microscopy. Muscles from ethanol-fed rats showed a low-grade myopathy and the diameters of individual type II fibres were reduced. Infrequent atrophic fibres were necrotic and undergoing phagocytosis. Ultrastructurally, there were no observable differences in the subcellular organelles of the alcohol-fed and control rats. It was concluded that alcohol causes a specific myopathic process in the rat, selectively affecting type II fibres. These changes correlate well with the abnormalities seen in human chronic alcoholic myopathy.

  8. The effect of 10 and 20 Gy single dose irradiation on the esophageal mucosa of the rabbit. An electron microscopic study

    SciTech Connect

    Hakansson, C.H.; Albertsson, M.; Palmegren, M. )

    1989-12-01

    The mucosa of rabbit esophagus was irradiated with single doses of 10 and 20 Gy respectively. Specimens were taken for scanning electron microscopy (SEM), and light microscopy investigations. Examinations were made 1-14 days after 10 Gy and 1-17 days after 20 Gy. Irradiation resulted in edema during the first days. The thickness of the epithelium was at its lowest value around day 5 after the administration of 10 Gy, and on days eight to ten after the administration of 20 Gy. Damage of the epithelium surface, as scored on SEM micrographs, was most pronounced on days eight to eleven after irradiation, showing a clear dose dependency. The second week after irradiation repair was seen concluding in an overshoot of the mucosal height. The amount of bacteria on the surface increased during the period of edema, and decreased when the damage was most pronounced.

  9. Stages in spermatogenesis of two species of caecilians, Ichthyophis tricolor and Uraeotyphlus cf. narayani (Amphibia: Gymnophiona): Light and electron microscopic study.

    PubMed

    Smita, Mathew; Oommen, Oommen V; Jancy, M George; Akbarsha, M A

    2004-07-01

    The sequential changes during spermatogenesis in the testis of two species of caecilians, Ichthyophis tricolor (Ichthyophiidae) and Uraeotyphlus cf. narayani (Uraeotyphliidae), of Western Ghats of Kerala, India, were traced using both histological techniques and transmission electron microscopy. The cell nests were assigned to stages in spermatogenesis based on the classification of van Oordt (1956, Thesis, Utrecht University). To the best of our knowledge, this is the first identification and ultrastructural description of stages in spermatogenesis in caecilians. The article illustrates not only the stages, but also the cell divisions, mitotic and meiotic, as specified. The observations indicate that, although caecilians have undergone considerable modifications in morphology and anatomy, including reproductive anatomy, in the context of a subterranean and concealed life, they appear to have conserved the typical amphibian pattern of spermatogenesis for the events of development of spermatids. PMID:15164370

  10. A scanning electron microscope study of the pecten oculi of the black kite (Milvus migrans): possible involvement of melanosomes in protecting the pecten against damage by ultraviolet light.

    PubMed Central

    Kiama, S G; Bhattacharjee, J; Maina, J N; Weyrauch, K D

    1994-01-01

    The pecten oculi of the black kite (Milvus migrans), a diurnally active bird of prey, has been examined by scanning electron microscopy. In this species the pecten consists of 12 highly vascularised pleats, held together apically by a heavily pigmented 'bridge' and projects freely into the vitreous body in the ventral part of the eye cup. Ascending and descending blood vessels of varying calibre, together with a profuse network of capillaries, essentially constitute the vascular framework of the pecten. A distinct distribution of melanosomes is discernible on the pecten, the concentration being highest at its apical end, moderate at the crest of the pleats and least at the basal and lateral margins. Overlying and within the vascular network, a close association between blood vessels and melanocytes is evident. It is conjectured that such an association may have evolved to augment the structural reinforcement of this nutritive organ in order to keep it firmly erectile within the gel-like vitreous. Such erectility may be an essential prerequisite for its optimal functioning, as well as in its overt use as a protective shield against the effects of ultraviolet light, which otherwise might lead to damage of the pectineal vessels. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 PMID:7649799

  11. Outer membrane of gram-negative bacteria. XVIII. Electron microscopic studies on porin insertion sites and growth of cell surface of Salmonella typhimurium.

    PubMed Central

    Smit, J; Nikaido, H

    1978-01-01

    Salmonella typhimurium contains three "major proteins" or "porins" (34K, 35K, and 36K) in the outer membrane. A mutant strain producing only the 35K porin was first grown in media containing high concentrations of NaCl to "repress" the porin synthesis and then was shifted into a medium without NaCl. The newly made porin molecules were then labeled with the ferritin-coupled antibody at various times after the shift, and the samples were examined by whole-mount, freeze-etching, and thin-section electron microscopy. These experiments showed that newly inserted porins appeared as discrete patches uniformly distributed over the surface of the cell and, furthermore, that the sites of adhesion between the inner and outer membrane were most probably the pathway by which the newly made porin molecules appeared on cell surface. The 34K and 36K porins were also inserted in the same manner, since the appearance of new porins at discrete sites all over the cell surface was also observed when cells with wild-type porin phenotype were treated with unlabeled antibody to block existing antigenic sites, subsequently regrown, and labeled with the ferritin-coupled antibody. Since porins comprise a major portion of the densely packed, relatively immobile, "protein framework" of the outer membrane, these results lead us to conclude that the outer membrane grows predominantly by diffuse intercalation rather than by the zonal growth mechanism. Images PMID:355240

  12. Testicular myxosporidiasis and ultrastructural characteristics of Myxobolus bufonis (Myxobolidae) infecting the Egyptian toad Bufo regularis (Bufonidae). A light and electron microscopic study.

    PubMed

    Morsy, Kareem; Semmler, Margit; Al-Olayan, Ebtsam; Mehlhorn, Heinz

    2015-11-01

    The phylum Myxozoa comprises more than 2180 species, almost all of which are considered to be obligate parasites of aquatic fishes and amphibians. They are dangerous pathogens responsible for severe economic losses. From March to September 2014, 40 adult male Bufo regularis (Bufonidae) captured from different areas at Giza province, Egypt, were surveyed for myxosporean parasitic infection. Of these, 22 (55%) were infected by histozoic plasmodia, which produced spores after rupture belonging to Myxosporidia. The present investigation introduced a new data for the recorded parasite observed by light and transmission electron microscopy. The infection was diagnosed as large clusters of macroscopic plasmodia embedded in the testicular tissue causing distortion at the site of infection. The host reaction was manifested by the encapsulation of the plasmodia with a thick layer of connective tissue. Plasmodia were whitish in color, elliptical to ovoid in shape measuring 0.54 ± 0.2 (0.34-0.63) mm in diameter. The spores were subspherical, reaching 7.1 ± 0.2 (6.2-8.4) μm in length and 6.3 ± 0.2 (5.8-7.0) μm in width with two equal-sized polar capsules regularly arranged at the anterior pole of each spore. They were 3.4 ± 0.2 (3.0-4.2) μm in length and 1.9 ± 0.2 (1.6-2.4) in width with 6-8 turns of polar filaments. Ultrastructural analysis showed that the plasmodia were surrounded by a plasma membrane with numerous projections and pinocytotic channels extended toward the host cell. The generative cells and the different developmental stages were arranged at the periphery of the plasmodia while immature and mature spores were centrally arranged. Sporogenesis, capsulogenesis, valvogenesis, and spore maturation of the present parasite were also described.

  13. A high-voltage scanning transmission electron microscope at Nagoya University.

    PubMed

    Hibino, M; Shimoyama, H; Maruse, S

    1989-07-01

    A high-voltage scanning transmission electron microscope (STEM) H-1250ST of the maximum accelerating voltage of 1.25 MV was constructed at Nagoya University in 1983. The microscope, equipped with a field-emission gun, is designed with high-level STEM performance as well as conventional transmission microscopy mode operation. The aim of developing the microscope, basic design schemes, principal instrumentation, and techniques developed are described.

  14. Imaging Single Atoms Using Secondary Electrons with an Aberration-Corrected Electron Microscope

    SciTech Connect

    Zhu, Y.; Inada, H.; Nakamura, K.; Wall, J.

    2009-09-20

    Aberration correction has embarked on a new frontier in electron microscopy by overcoming the limitations of conventional round lenses, providing sub-angstrom-sized probes. However, improvement of spatial resolution using aberration correction so far has been limited to the use of transmitted electrons both in scanning and stationary mode, with an improvement of 20-40%. In contrast, advances in the spatial resolution of scanning electron microscopes (SEMs), which are by far the most widely used instrument for surface imaging at the micrometre-nanometre scale, have been stagnant, despite several recent efforts. Here, we report a new SEM, with aberration correction, able to image single atoms by detecting electrons emerging from its surface as a result of interaction with the small probe. The spatial resolution achieved represents a fourfold improvement over the best-reported resolution in any SEM. Furthermore, we can simultaneously probe the sample through its entire thickness with transmitted electrons. This ability is significant because it permits the selective visualization of bulk atoms and surface ones, beyond a traditional two-dimensional projection in transmission electron microscopy. It has the potential to revolutionize the field of microscopy and imaging, thereby opening the door to a wide range of applications, especially when combined with simultaneous nanoprobe spectroscopy.

  15. The morphology of the lung of the black mamba Dendroaspis polylepis (Reptilia: Ophidia: Elapidae). A scanning and transmission electron microscopic study.

    PubMed Central

    Maina, J N

    1989-01-01

    The lung of a snake, the black mamba (Dendroaspis polylepis), has been investigated by scanning and transmission electron microscopy. This species has only one lung, the right, which is long and occupies most of the pleuro-peritoneal cavity. Grossly, the lung could be divided into two discrete anatomical regions: an anterior respiratory area made up of a honeycomb network of capillary-bearing partitions, and a posterior membranous saccular region. The exchange region consisted of a central air duct, the bronchus, which was delineated both dorsally and laterally by morphologically and spatially distinct hierarchically arranged septa. The primary septa gave rise to the secondary septa from which the much deeper peripherally situated tertiary septa that formed the immediate openings to the faveoli arose. The faveoli were rather parallel elongated pockets separated by partitions, the interfaveolar septa, and terminated peripherally on the pleura. A double capillary disposition of the blood capillaries was observed on the relatively thick primary and secondary septa. These septa were lined by a heterogenous epithelium made up of ciliated cells, secretory cells, and smooth squamous cells. This epithelium was continued from the trachea and the bronchus. At the faveolar level the blood capillaries exhibited a single system where they formed a matrix on both sides of the partitions. The surface of the faveoli was covered by two types of cells: Type I cells were squamous and their remarkably attenuated cytoplasmic arborisations were notably extensive while the Type II cells were rather cuboidal, bore stubby microvilli and contained the characteristic osmiophilic lamellated bodies. On the basis of the clearly evident complete differentiation of the pneumocytes and the presence of both the double and single capillary systems, it was observed that this lung, and apparently the reptilian lung in general, manifests a transitional developmental and structural stage in the

  16. The structure of pedicle and hard antler bone in the European roe deer (Capreolus capreolus): a light microscope and backscattered electron imaging study

    PubMed Central

    Kierdorf, Uwe; Flohr, Stefan; Gomez, Santiago; Landete-Castillejos, Tomas; Kierdorf, Horst

    2013-01-01

    Deer antlers are deciduous bony structures that develop from permanent frontal outgrowths, the pedicles. While growth and bone architecture of antlers have been studied in greater detail, information on pedicle formation and structure is scarce. The present study provides information on the structure of pedicle and hard antler bone in the European roe deer. A pronounced seasonal variation in pedicle architecture was observed, with high porosity around antler casting and a very compact bone structure during the hard antler stage. These observations suggest a corresponding marked variation also in the biomechanical properties of the pedicles. The seasonally alternating extensive resorption and formation processes make the pedicles of older deer heavily remodeled structures. Pedicles increase in thickness by apposition of primary bone that subsequently becomes replaced by secondary osteons. The antler cortex of roe deer is largely composed of a tubular framework of woven bone trabeculae with some remnants of mineralized cartilage, and primary osteons that have filled in the intertrabecular spaces. Secondary osteons are scarce, denoting little remodeling in antlers, which can be related to their short lifespan. The occurrence of cement lines around primary osteons indicates resorption on the trabecular scaffold prior to infilling of the intertrabecular spaces. The outer cortex showed a higher autofluorescence and a more immature structure than the main cortex, suggesting that it was secondarily formed by periosteal activity. Pedicles and antlers constitute a functional entity, and future histological and/or biomechanical studies should therefore consider both components of the cranial appendages. PMID:23961846

  17. In situ conversion of nanostructures from solid to hollow in transmission electron microscopes using electron beam.

    PubMed

    El Mel, Abdel-Aziz; Bittencourt, Carla

    2016-06-01

    With the current development of electron beam sources, the use of transmission electron microscopes is no more limited to imaging or chemical analysis but has rather been extended to nanoengineering. This includes the e-beam induced growth, etching and structural transformation of nanomaterials. In this review we summarize recent progress on the e-beam induced morphological transformation of nanostructures from solid to hollow. We provide a detailed account of the processes reported so far in the literature with a special emphasis on the mechanistic understanding of the e-beam induced hollowing of nanomaterials. Through an important number of examples, we discuss how one can achieve a precise control of such hollowing processes by understanding the fundamental mechanisms occurring at the atomic scale during the irradiation of solid nanostructures. Finally, we conclude with remarks and our own view on the prospective future directions of this research field.

  18. In situ conversion of nanostructures from solid to hollow in transmission electron microscopes using electron beam.

    PubMed

    El Mel, Abdel-Aziz; Bittencourt, Carla

    2016-06-01

    With the current development of electron beam sources, the use of transmission electron microscopes is no more limited to imaging or chemical analysis but has rather been extended to nanoengineering. This includes the e-beam induced growth, etching and structural transformation of nanomaterials. In this review we summarize recent progress on the e-beam induced morphological transformation of nanostructures from solid to hollow. We provide a detailed account of the processes reported so far in the literature with a special emphasis on the mechanistic understanding of the e-beam induced hollowing of nanomaterials. Through an important number of examples, we discuss how one can achieve a precise control of such hollowing processes by understanding the fundamental mechanisms occurring at the atomic scale during the irradiation of solid nanostructures. Finally, we conclude with remarks and our own view on the prospective future directions of this research field. PMID:27172892

  19. [Effect of a 6-week vitamin A-deficient diet on the sensory cells of the inner ear. Light and electron microscopic studies].

    PubMed

    Löhle, E

    1980-09-01

    Histologic studies of the inner ear in rats with chronic vitamin A deficiency have produced contradicting results. In our own electronmicroscope investigations of the inner ear of young rats after a six week vitamin A deficit diet we found a lacking of the cuticle in the outer hair cells and a subtotally lacking of the cuticle in the inner hair cells. Furthermore, we found changes in the reticular system of the intermediate zone. These morphologic changes together with the recent findings of high concentrations of vitamin A in the corti organ support the hypothesis that the acoustic sensory receptors contain or functionally depend upon vitamin A.

  20. Arterial supply of the choriocapillaris of anuran amphibians (Rana temporaria, Rana esculenta). Scanning electron-microscopic (SEM) study of microcorrosion casts.

    PubMed

    Miodoński, A J; Bär, T

    1987-07-01

    The pattern of the vascular supply to the choroid of the frog eye was studied in toto with the use of the injection-replication-SEM technique. The choroid of anuran amphibians is composed mainly of the choriocapillaris. In both species studied (Rana temporaria, Rana esculenta), an independent arterial supply to the choriocapillaris supplemented that from the ciliary arteries. This additional vascular route arises from the optic artery, a separate branch of the arteria infundibularis superficialis. The optic artery, accompanied by its vein within the vascular sheath of the optic nerve, joins the rich arterial capillary network of the choriocapillaris and supplies the posterior pole of the ocular bulb. The superficial capillary network displays a dense collar around the entrance of the optic nerve into the eye and is composed of a circular meshwork of small capillaries, several layers deep. More peripherally, however, it becomes a single layered. This capillary network, as a whole, establishes numerous connections with the adjacent choriocapillaris at the posterior pole of the ocular bulb. In anuran amphibians the complex arrangement of both arterial systems supporting the choriocapillaris may be regarded as a more complete equivalent of the short posterior ciliary arteries of mammals.

  1. Probing plasmons in three dimensions by combining complementary spectroscopies in a scanning transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Hachtel, J. A.; Marvinney, C.; Mouti, A.; Mayo, D.; Mu, R.; Pennycook, S. J.; Lupini, A. R.; Chisholm, M. F.; Haglund, R. F.; Pantelides, S. T.

    2016-04-01

    The nanoscale optical response of surface plasmons in three-dimensional metallic nanostructures plays an important role in many nanotechnology applications, where precise spatial and spectral characteristics of plasmonic elements control device performance. Electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) within a scanning transmission electron microscope have proven to be valuable tools for studying plasmonics at the nanoscale. Each technique has been used separately, producing three-dimensional reconstructions through tomography, often aided by simulations for complete characterization. Here we demonstrate that the complementary nature of the two techniques, namely that EELS probes beam-induced electronic excitations while CL probes radiative decay, allows us to directly obtain a spatially- and spectrally-resolved picture of the plasmonic characteristics of nanostructures in three dimensions. The approach enables nanoparticle-by-nanoparticle plasmonic analysis in three dimensions to aid in the design of diverse nanoplasmonic applications.

  2. An aberration corrected photoemission electron microscope at the advanced light source

    SciTech Connect

    Feng, J.; MacDowell, A.A.; Duarte, R.; Doran, A.; Forest, E.; Kelez, N.; Marcus, M.; Munson, D.; Padmore, H.; Petermann, K.; Raoux, S.; Robin, D.; Scholl, A.; Schlueter, R.; Schmid, P.; Stohr, J.; Wan, W.; Wei, D.H.; Wu, Y.

    2003-11-01

    Design of a new aberration corrected Photoemission electron microscope PEEM3 at the Advanced Light Source is outlined. PEEM3 will be installed on an elliptically polarized undulator beamline and will be used for the study of complex materials at high spatial and spectral resolution. The critical components of PEEM3 are the electron mirror aberration corrector and aberration-free magnetic beam separator. The models to calculate the optical properties of the electron mirror are discussed. The goal of the PEEM3 project is to achieve the highest possible transmission of the system at resolutions comparable to our present PEEM2 system (50 nm) and to enable significantly higher resolution, albeit at the sacrifice of intensity. We have left open the possibility to add an energy filter at a later date, if it becomes necessary driven by scientific need to improve the resolution further.

  3. Topography and immunocytochemical characterization of nerve fibers in the leptomeningeal compartments of the rat. A light- and electron-microscopical study.

    PubMed

    Fricke, B; von Düring, M; Andres, K H

    1997-01-01

    The localization of peptidergic, catecholaminergic, and nitroxidergic nerve fibers in the ventral leptomeningeal connective tissue compartment was studied in whole-mount preparations and serial semithin and ultrathin sections. For immunocytochemistry, whole-mount preparations of the leptomeninges and ventral brain slices with the meninges were incubated as free-floating specimens with primary antibodies against protein gene product 9.5 (PGP 9.5), substance P (SP), calcitonin gene-related peptide (CGRP), dopamine beta-hydroxylase (DbetaH), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), and nitric oxide synthase (NOS) using the avidin-biotin-peroxidase method. Based on the regional differences of the connective tissue organization, the leptomeninx is subdivided into the pial, trabecular, and adventitial leptomeninx. The antibody PGP 9.5 stains all unmyelinated nerve fibers in the leptomeninx. Although the highest density of nerve fibers occurs in the adventitial leptomeninx, nerve fibers, and terminals are additionally present in the trabecular and pial leptomeninx. DbetaH-, NPY-, VIP- and NOS-immunoreactive (IR) nerve fibers occur exclusively in the adventitial leptomeninx forming neuromuscular junctions. CGRP- and SP-IR nerve fibers are localized in all three leptomeningeal compartments where they terminate close to the subarachnoid space (type 1) or within the connective tissue (type 2). Due to their morphological and immunocytochemical characterization a possible chemo-, mechano- or nociceptive function is discussed in the context of pathophysiological aspects.

  4. Three-Dimensional Aspects of the Lingual Papillae and Their Connective Tissue Cores in the Tongue of Rats: A Scanning Electron Microscope Study

    PubMed Central

    Reginato, Gabriela de Souza; Watanabe, Ii-sei; Ciena, Adriano Polican

    2014-01-01

    The aim of the present study was to describe the tridimensional morphological characteristics of the lingual papillae and their connective tissue cores (CTCs) in Sprague Dawley rats. Four types of papillae were reported on the dorsal surface. Filiform papillae were distributed on the tongue surface and after epithelial maceration a conic and multifilamentary shape of the CTCs was revealed. Fungiform papillae were reported on the rostral and middle regions covered by a squamous epithelium. After the removal of the epithelium, the shape of a volcano with the taste orifice at its top was noted. Foliate papillae were composed of five pairs of epithelial folds situated on the lateral-caudal margin of the tongue. After the removal of the epithelium, they were shown to be limited by thin laminar projections. The vallate papilla with an oval shape was present in the caudal region and delimited by an incomplete groove. The morphological characteristics of the lingual papillae of Sprague Dowley rats, three-dimensional SEM images, and the types of papillae on the dorsal surface were similar to those reported previously in other rodent mammals. The maceration technique revealed the details of extracellular matrix with varied shapes form of connective tissue cores. PMID:25436229

  5. Colchicine myopathy: a vacuolar myopathy with selective type I muscle fiber involvement. An immunohistochemical and electron microscopic study of two cases.

    PubMed

    Fernandez, C; Figarella-Branger, D; Alla, P; Harlé, J-R; Pellissier, J-F

    2002-02-01

    Colchicine, a microtubule polymerization inhibitor, can very occasionally induce myopathy. We report two cases of colchicine myopathy. Both patients presented with myalgia and proximal muscle weakness. The first patient, an 80-year-old woman, had chronic renal failure related to renal amyloidosis. She had been treated by colchicine for 4 months. The second, a 75-year-old man with normal renal function, suffering from gout, was treated by colchicine for 3 weeks. Muscle biopsies displayed the same alterations, but the degree of severity was different. Conventional histology revealed vacuolar changes characterized by acid phosphatase-positive vacuoles and myofibrillar disarray foci. The lesions were selective for type I fibers. Ultrastructural study demonstrated autophagic vacuoles. Most of the vacuoles expressed dystrophin but not merosin. Several fibers reacted with anti-MHC class I antibody and granular deposits of membrane attack complex were observed on the surface of numerous myofibers. Anti-alphaB-crystallin antibody strongly reacted with vacuolar content. Physiopathologically, microtubules are primordial for vesicle movements and colchicine induces autophagic vacuole accumulation by preventing their fusion with lysosomes. The selective type I involvement is probably due to the higher tubulin amount in type I fibers. AlphaB-crystallin overexpression is related to its microtubule protection properties. Moreover, we suggest that vacuoles randomly floating in sarcoplasm might occasionally meet the plasma membrane and open in the extracellular space, leading to complement activation. Accurate diagnosis of colchicine myopathy is relevant because the treatment is based on colchicine interruption.

  6. Skin regenerated from cultured epithelial autografts on full-thickness burn wounds from 6 days to 5 years after grafting. A light, electron microscopic and immunohistochemical study.

    PubMed

    Compton, C C; Gill, J M; Bradford, D A; Regauer, S; Gallico, G G; O'Connor, N E

    1989-05-01

    Regeneration of skin from cultured keratinocyte autografts used in the treatment of full-thickness burn wounds was studied in 21 pediatric patients from 6 days to 5 years after grafting. Findings were compared both to controls of age- and site-matched normal skin and to controls for epithelial wound-healing, re-epithelialized interstices of meshed split-thickness skin grafts of comparable postgrafting age. Six days after transplantation, a mildly hypertrophic, flat epidermis with all normal strata had regenerated, and the process of de novo dermal-epidermal junction formation had begun. Hemidesmosomes, basal lamina, and anchoring fibrils reformed conjointly in punctate fashion along the attachment face of the grafts. Within 3 to 4 weeks, the dermal-epidermal junction was complete, but full maturation of anchoring fibrils required more than a year. The process was comparable to that observed in meshed graft interstices. Rete ridges regenerated from 6 weeks to 1 year after grafting. The subjacent connective tissue initially healed to form normal scar, but it remodeled dramatically, regenerated elastin, and resembled a true dermis within 4 to 5 years. Meshed-graft interstice controls showed no rete ridge regeneration, subepithelial connective tissue remodeling, or elastin production up to 5 years after grafting. Langerhans cells repopulated grafts within 1 week, and normal population densities were reached within 2 to 6 months. After 1 year, Langerhans cell densities were increased compared with normal skin but were lower than those in age-matched meshed graft controls. Melanocytes were present in cultures at the time of transplantation, but functional epidermal melanin units were not seen in groin- or axilla-derived grafts for 6 to 8 weeks or in sole-derived epidermis until a year or more after transplantation. Normal histologic features were maintained for years after grafting. Transitory pathologic changes including parakeratosis, dyskeratosis, and intraepithelial

  7. Confocal laser scanning microscopic photoconversion: a new method to stabilize fluorescently labeled cellular elements for electron microscopic analysis

    PubMed Central

    Colello, Raymond J.; Tozer, Jordan; Henderson, Scott C.

    2012-01-01

    Photoconversion, the method by which a fluorescent dye is transformed into a stable, osmiophilic product that can be visualized by electron microscopy, is the most widely used method to enable the ultrastructural analysis of fluorescently-labeled cellular structures. Nevertheless, the conventional method of photoconversion using widefield fluorescence microscopy requires long reaction times and results in low resolution cell targeting. Accordingly, we have developed a photoconversion method that ameliorates these limitations by adapting confocal laser scanning microscopy to the procedure. We have found that this method greatly reduces photoconversion times as compared to conventional wide field microscopy. Moreover, region of interest scanning capabilities of a confocal microscope facilitate the targeting of the photoconversion process to individual cellular or subcellular elements within a fluorescent field. This reduces the area of the cell exposed to light energy, thereby reducing the ultrastructural damage common to this process when widefield microscopes are employed. PMID:23042499

  8. Manipulation of nanoparticles of different shapes inside a scanning electron microscope

    PubMed Central

    Polyakov, Boris; Dorogin, Leonid M; Butikova, Jelena; Antsov, Mikk; Oras, Sven; Lõhmus, Rünno; Kink, Ilmar

    2014-01-01

    Summary In this work polyhedron-like gold and sphere-like silver nanoparticles (NPs) were manipulated on an oxidized Si substrate to study the dependence of the static friction and the contact area on the particle geometry. Measurements were performed inside a scanning electron microscope (SEM) that was equipped with a high-precision XYZ-nanomanipulator. To register the occurring forces a quartz tuning fork (QTF) with a glued sharp probe was used. Contact areas and static friction forces were calculated by using different models and compared with the experimentally measured force. The effect of NP morphology on the nanoscale friction is discussed. PMID:24605279

  9. Light and scanning electron microscopic investigations on MiteStop-treated poultry red mites.

    PubMed

    Locher, Nina; Klimpel, Sven; Abdel-Ghaffar, Fathy; Al Rasheid, Khaled A S; Mehlhorn, Heinz

    2010-07-01

    Recent studies of the neem seed product MiteStop showed that it has a good acaricidal effect against all developmental stages of the poultry red mite, Dermanyssus gallinae. In vitro tests proved an efficacy at direct contact, as well as by fumigant toxicity. Light and scanning electron microscopic (SEM) investigations showed no clear, morphologically visible signs of an effect caused by fumigant toxicity. Direct contact with the neem product, however, seemed to be of great impact. Chicken mites turned dark brown or even black after being treated with the neem product. SEM analysis showed damages along the body surface of the mites. PMID:20563823

  10. Comparison of Electron Imaging Modes for Dimensional Measurements in the Scanning Electron Microscope.

    PubMed

    Postek, Michael T; Vladár, András E; Villarrubia, John S; Muto, Atsushi

    2016-08-01

    Dimensional measurements from secondary electron (SE) images were compared with those from backscattered electron (BSE) and low-loss electron (LLE) images. With the commonly used 50% threshold criterion, the lines consistently appeared larger in the SE images. As the images were acquired simultaneously by an instrument with the capability to operate detectors for both signals at the same time, the differences cannot be explained by the assumption that contamination or drift between images affected the SE, BSE, or LLE images differently. Simulations with JMONSEL, an electron microscope simulator, indicate that the nanometer-scale differences observed on this sample can be explained by the different convolution effects of a beam with finite size on signals with different symmetry (the SE signal's characteristic peak versus the BSE or LLE signal's characteristic step). This effect is too small to explain the >100 nm discrepancies that were observed in earlier work on different samples. Additional modeling indicates that those discrepancies can be explained by the much larger sidewall angles of the earlier samples, coupled with the different response of SE versus BSE/LLE profiles to such wall angles. PMID:27452278

  11. Note: A scanning electron microscope sample holder for bidirectional characterization of atomic force microscope probe tips

    SciTech Connect

    Eisenstein, Alon; Goh, M. Cynthia

    2012-03-15

    A novel sample holder that enables atomic force microscopy (AFM) tips to be mounted inside a scanning electron microscopy (SEM) for the purpose of characterizing the AFM tips is described. The holder provides quick and easy handling of tips by using a spring clip to hold them in place. The holder can accommodate two tips simultaneously in two perpendicular orientations, allowing both top and side view imaging of the tips by the SEM.

  12. Comparison of marginal adaptation of mineral trioxide aggregate, glass ionomer cement and intermediate restorative material as root-end filling materials, using scanning electron microscope: An in vitro study

    PubMed Central

    Gundam, Sirisha; Patil, Jayaprakash; Venigalla, Bhuvan Shome; Yadanaparti, Sravanthi; Maddu, Radhika; Gurram, Sindhura Reddy

    2014-01-01

    Aim: The present study compares the marginal adaption of Mineral Trioxide Aggregate (MTA), Glass Ionomer Cement (GIC) and Intermediate Restorative Material (IRM) as root-end filling materials in extracted human teeth using Scanning Electron Microscope (SEM). Materials and Methods: Thirty single rooted human teeth were obturated with Gutta-percha after cleaning and shaping. Apical 3 mm of roots were resected and retrofilled with MTA, GIC and IRM. One millimeter transverse section of the retrofilled area was used to study the marginal adaptation of the restorative material with the dentin. Mounted specimens were examined using SEM at approximately 15 Kv and 10-6 Torr under high vacuum condition. At 2000 X magnification, the gap size at the material-tooth interface was recorded at 2 points in microns. Statistical Analysis: One way ANOVA Analysis of the data from the experimental group was carried out with gap size as the dependent variable, and material as independent variable. Results: The lowest mean value of gap size was recorded in MTA group (0.722 ± 0.438 μm) and the largest mean gap in GIC group (1.778 ± 0.697 μm). Conclusion: MTA showed least gap size when compared to IRM and GIC suggesting a better marginal adaptation. PMID:25506146

  13. [Examination of the uterine cervix using the scanning electron microscope].

    PubMed

    Lerat, M F; Magre, J; Connehaye, P; Lerat, H; Barreau, A

    1975-01-01

    Scanning by electron microscopy of the cervix of the uterus allows us to study the various aspects, both normal and pathological, as well as the architecture of sections of the organ. All the same, as in all practical examinations carried out using scanning we have to beware of pictures that are but artefacts due to the method of preparation. The views obtained from a normal cervix of from pathological cervices show very different aspects. In the normal cervix the surfaces are more or less smooth and the architecture of the deeper levels shows a thick and regular texture. Infectious lesions of the outer aspect of the cervix show punched-out patterns, like craters, which penetrate more or less deeply into the sub-epithelial plane. While cervical dysplasia shows little except perhaps a more or less bossed-up epithelial surface, cancer of the cervix on the other hand shows a pavement pattern which is irregular. The pavements are formed by buds which are separated by faults which are more or less deep. In section the structures show a degree of disorientation in the texture. After treatment with radium the appearance is rather like ground glass of spiders webs and the architecture of the structures seems to be pock-marked and chaotic.

  14. Comparative in vitro evaluation of internal adaptation of resin-modified glass ionomer, flowable composite and bonding agent applied as a liner under composite restoration: A scanning electron microscope study

    PubMed Central

    Soubhagya, M; Goud, K Mallikarjun; Deepak, B S; Thakur, Sophia; Nandini, T N; Arun, J

    2015-01-01

    Background: The use of resin-modified glass Ionomer cement in sandwich technique is widely practiced with the advent of various newer generation of composites the bond between resin-modified glass Ionomer and these resins should be validated. This study is done to evaluate the interfacial microgaps between different types of liners and dentin, liners and composite (Filtek p60 [FLp60]) using scanning electron microscope (SEM). Materials and Methods: Standardized Class V preparations were performed in buccal/lingual surfaces of 30 caries, crack and defect-free extracted human third molars. The prepared teeth were divided into three groups. Group I: Single bond (SB), Group II: SB + synergy flow, Group III: SB + vitrebond. They were restored with composite resin FLp60, according to the manufacturer instructions. The SB + vitrebond, cross-sectioned through the canter of the restoration. The specimens were fixed, dehydrated, polished, and processed for SEM. The internal adaptation of the materials to the axial wall was analyzed under SEM with ×1000 magnification. Results: The data obtained were analyzed with nonparametric tests (Kruskal–Wallis, P < 0.05). flowable composite or resin-modified glass ionomer applied in conjunction with adhesive resulted in statistically wider microgaps than occurred when the dentin was only hybridized prior to the restoration. Conclusion: Hybridization of dentin only provides superior sealing of the dentin-restoration interface than does flowable resin or resin-modified glass ionomer. PMID:25954067

  15. Light and electron microscopic changes in the myocardium of influenza-infected turkeys.

    PubMed

    McKenzie, B E; Easterday, B C; Will, J A

    1972-11-01

    Virus isolation and titration, electrocardiography, enzyme assays and light and electron microscopic studies were undertaken in male turkeys infected with influenza A/turkey/Ontario/7732/66 virus to determine its potential role in the genesis of heart disease. Virus was isolated from the heart initially before a demonstrable viremia and terminally in declining serum viral titer. Virus was isolated from the heart muscle as early as 1 day postinoculation. Highest viral titers were found in the heart at 6 days postinoculation and coincided with maximum elevations of serum glutamic-oxalacetic transaminase and lactic acid dehydrogenase, microscopic lesions in the heart and cardiac arrhythmias. Microscopic lesions in the heart were first detected at 4 days postinoculation and consisted of disseminated areas of necrosis, focal myocarditis, pericarditis and endocarditis. Alterations in myocardial ultrastructure which followed viral infection included fragmentation and dissolution of myofibrils, dilation of the sarcotubular system, increase in membrane vesicle formation in the region of the endoplasmic reticulum, discontinuity of the sarcolemma, proliferation of mitochondrial population, swelling of mitochondria with separation and disruption of the cristae, and the presence of intramitochondrial and perinuclear densities.

  16. Instrumental developments for in situ breakdown experiments inside a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Muranaka, T.; Blom, T.; Leifer, K.; Ziemann, V.

    2011-11-01

    Electrical discharges in accelerating structures are one of the key issues limiting the performance of future high energy accelerators such as the Compact Linear Collider (CLIC). Fundamental understanding of breakdown phenomena is an important part of the CLIC feasibility study. The present work concerns the experimental study of breakdown using Scanning Electron Microscopes (SEMs). An SEM gives us the opportunity to achieve high electrical gradients of 1 kV/ μm which corresponds to 1 GV/m by exciting a probe needle with a high voltage power supply and controlling the positioning of the needle with a linear piezo motor. The gap between the needle tip and the surface is controlled with sub-micron precision. A second electron microscope equipped with a Focused Ion Beam (FIB) is used to create surface corrugations and to sharpen the probe needle to a tip radius of about 50 nm. Moreover it is used to prepare cross-sections of a voltage breakdown area in order to study the geometrical surface damages as well as the elemental composition of the breakdown.

  17. Electron microscopic analysis of partially replicated bacteriophage T7 DNA.

    PubMed Central

    Burck, K B; Scraba, D G; Miller, R C

    1979-01-01

    Partially replicated bacteriophage T7 DNA was isolated from Escherichia coli infected with UV-irradiated T7 bacteriophage and was analyzed by electron microscopy. The analysis determined the distribution of eye forms and forks in the partially replicated molecules. Eye forms and forks in unit length molecules were aligned with respect to the left end of the T7 genome, and segments were scored for replication in each molecule. The resulting histogram showed that only the left 25 to 30% of the molecules was replicated. Several different origins of DNA replication were used to initiate replication in the UV-irradiated experiments in which 32P-labeled progeny DNA from UV-irradiated phage was annealed with ordered restriction fragments of T7 DNA (K. B. Burck and R. C. Miller, Jr., Proc. Natl. Acad. Sci. U.S.A. 75:6144--6148, 1978). Both analyses support partial-replica hypotheses (N. A. Barricelli and A. H. Doermann, Virology 13:460--476, 1961; Doermann et al., J. Cell. comp. Physiol. 45[Suppl.]:51--74, 1955) as an explanation for the distribution of marker rescue frequencies during cross-reactivation; i.e., replication proceeds in a bidirectional manner from an origin to a site of UV damage, and those regions of the genome which replicate most efficiently are rescued most efficiently by a coinfecting phage. In addition, photoreactivation studies support the hypothesis that thymine dimers are the major UV damage blocking cross-reactivation in the right end of the T7 genome. Images PMID:291738

  18. Electronic Single Molecule Measurements with the Scanning Tunneling Microscope

    NASA Astrophysics Data System (ADS)

    Im, Jong One

    Richard Feynman said "There's plenty of room at the bottom". This inspired the techniques to improve the single molecule measurements. Since the first single molecule study was in 1961, it has been developed in various field and evolved into powerful tools to understand chemical and biological property of molecules. This thesis demonstrates electronic single molecule measurement with Scanning Tunneling Microscopy (STM) and two of applications of STM; Break Junction (BJ) and Recognition Tunneling (RT). First, the two series of carotenoid molecules with four different substituents were investigated to show how substituents relate to the conductance and molecular structure. The measured conductance by STM-BJ shows that Nitrogen induces molecular twist of phenyl distal substituents and conductivity increasing rather than Carbon. Also, the conductivity is adjustable by replacing the sort of residues at phenyl substituents. Next, amino acids and peptides were identified through STM-RT. The distribution of the intuitive features (such as amplitude or width) are mostly overlapped and gives only a little bit higher separation probability than random separation. By generating some features in frequency and cepstrum domain, the classification accuracy was dramatically increased. Because of large data size and many features, supporting vector machine (machine learning algorithm for big data) was used to identify the analyte from a data pool of all analytes RT data. The STM-RT opens a possibility of molecular sequencing in single molecule level. Similarly, carbohydrates were studied by STM-RT. Carbohydrates are difficult to read the sequence, due to their huge number of possible isomeric configurations. This study shows that STM-RT can identify not only isomers of mono-saccharides and disaccharides, but also various mono-saccharides from a data pool of eleven analytes. In addition, the binding affinity between recognition molecule and analyte was investigated by comparing with

  19. High-resolution, high-throughput imaging with a multibeam scanning electron microscope

    PubMed Central

    EBERLE, AL; MIKULA, S; SCHALEK, R; LICHTMAN, J; TATE, ML KNOTHE; ZEIDLER, D

    2015-01-01

    Electron–electron interactions and detector bandwidth limit the maximal imaging speed of single-beam scanning electron microscopes. We use multiple electron beams in a single column and detect secondary electrons in parallel to increase the imaging speed by close to two orders of magnitude and demonstrate imaging for a variety of samples ranging from biological brain tissue to semiconductor wafers. Lay Description The composition of our world and our bodies on the very small scale has always fascinated people, making them search for ways to make this visible to the human eye. Where light microscopes reach their resolution limit at a certain magnification, electron microscopes can go beyond. But their capability of visualizing extremely small features comes at the cost of a very small field of view. Some of the questions researchers seek to answer today deal with the ultrafine structure of brains, bones or computer chips. Capturing these objects with electron microscopes takes a lot of time – maybe even exceeding the time span of a human being – or new tools that do the job much faster. A new type of scanning electron microscope scans with 61 electron beams in parallel, acquiring 61 adjacent images of the sample at the same time a conventional scanning electron microscope captures one of these images. In principle, the multibeam scanning electron microscope’s field of view is 61 times larger and therefore coverage of the sample surface can be accomplished in less time. This enables researchers to think about large-scale projects, for example in the rather new field of connectomics. A very good introduction to imaging a brain at nanometre resolution can be found within course material from Harvard University on http://www.mcb80x.org/# as featured media entitled ‘connectomics’. PMID:25627873

  20. Electronic structure of hydrogenated diamond: Microscopical insight into surface conductivity

    NASA Astrophysics Data System (ADS)

    Iacobucci, S.; Alippi, Paola; Calvani, P.; Girolami, M.; Offi, F.; Petaccia, L.; Trucchi, D. M.

    2016-07-01

    We have correlated the surface conductivity of hydrogen-terminated diamond to the electronic structure in the Fermi region. Significant density of electronic states (DOS) in proximity of the Fermi edge has been measured by photoelectron spectroscopy (PES) on surfaces exposed to air, corresponding to a p -type electric conductive regime, while upon annealing a depletion of the DOS has been achieved, resembling the diamond insulating state. The surface and subsurface electronic structure has been determined, exploiting the different probing depths of PES applied in a photon energy range between 7 and 31 eV. Ab initio density functional calculations including surface charge depletion and band-bending effects favorably compare with electronic states measured by angular-resolved photoelectron spectroscopy. Such states are organized in the energy-momentum space in a twofold structure: one, bulk-derived, band disperses in the Γ -X direction with an average hole effective mass of (0.43 ±0.02 ) m0 , where m0 is the bare electron mass; a second flatter band, with an effective mass of (2.2 ±0.9 ) m0 , proves that a hole gas confined in the topmost layers is responsible for the conductivity of the (2 ×1 ) hydrogen-terminated diamond (100 ) surface.

  1. Nanometres-resolution Kikuchi patterns from materials science specimens with transmission electron forward scatter diffraction in the scanning electron microscope.

    PubMed

    Brodusch, N; Demers, H; Gauvin, R

    2013-04-01

    A charge-coupled device camera of an electron backscattered diffraction system in a scanning electron microscope was positioned below a thin specimen and transmission Kikuchi patterns were collected. Contrary to electron backscattered diffraction, transmission electron forward scatter diffraction provides phase identification and orientation mapping at the nanoscale. The minimum Pd particle size for which a Kikuchi diffraction pattern was detected and indexed reliably was 5.6 nm. An orientation mapping resolution of 5 nm was measured at 30 kV. The resolution obtained with transmission electron forward scatter diffraction was of the same order of magnitude than that reported in electron nanodiffraction in the transmission electron microscope. An energy dispersive spectrometer X-ray map and a transmission electron forward scatter diffraction orientation map were acquired simultaneously. The high-resolution chemical, phase and orientation maps provided at once information on the chemical form, orientation and coherency of precipitates in an aluminium-lithium 2099 alloy.

  2. Angularly-selective transmission imaging in a scanning electron microscope.

    PubMed

    Holm, Jason; Keller, Robert R

    2016-08-01

    This work presents recent advances in transmission scanning electron microscopy (t-SEM) imaging control capabilities. A modular aperture system and a cantilever-style sample holder that enable comprehensive angular selectivity of forward-scattered electrons are described. When combined with a commercially available solid-state transmission detector having only basic bright-field and dark-field imaging capabilities, the advances described here enable numerous transmission imaging modes. Several examples are provided that demonstrate how contrast arising from diffraction to mass-thickness can be obtained. Unanticipated image contrast at some imaging conditions is also observed and addressed. PMID:27179301

  3. Angularly-selective transmission imaging in a scanning electron microscope.

    PubMed

    Holm, Jason; Keller, Robert R

    2016-08-01

    This work presents recent advances in transmission scanning electron microscopy (t-SEM) imaging control capabilities. A modular aperture system and a cantilever-style sample holder that enable comprehensive angular selectivity of forward-scattered electrons are described. When combined with a commercially available solid-state transmission detector having only basic bright-field and dark-field imaging capabilities, the advances described here enable numerous transmission imaging modes. Several examples are provided that demonstrate how contrast arising from diffraction to mass-thickness can be obtained. Unanticipated image contrast at some imaging conditions is also observed and addressed.

  4. Architecture of dermatophyte cell Walls: Electron microscopic and biochemical analysis

    NASA Technical Reports Server (NTRS)

    Nozawa, Y.; Kitajima, Y.

    1984-01-01

    A review with 83 references on the cell wall structure of dermatophytes is presented. Topics discussed include separation and preparation of cell walls; microstructure of cell walls by electron microscopy; chemical composition of cell walls; structural model of cell walls; and morphological structure of cell walls.

  5. The Effect of Systemic Delivery of Aminoguanidine versus Doxycycline on the Resorptive Phase of Alveolar Bone Following modified Widman Flap in Diabetic Rats: A Histopathological and Scanning Electron Microscope (SEM) study

    PubMed Central

    Tella, E; Aldahlawi, S; Eldeeb, A; El Gazaerly, H

    2014-01-01

    Objectives Aminoguanidine (guanylhydrazinehydrochloride) is a drug that prevents many of the classical systemic complications of diabetes including diabetic osteopenia through its inhibitory activity on the accumulation of advanced glycation end –products (AGEs). The aim of the present study was to evaluate the effectiveness of aminoguanidine versus doxycycline in reducing alveolar bone resorption following mucoperiosteal flap in diabetic rats, using the conventional histopathology and scanning electron microscope (SEM). Methods Twenty-seven male albino rats were used in this study. Periodontal defects were induced experimentally on lower anterior teeth. All rats were subjected to induction of diabetes, by IV injection of the pancreatic B-cells toxin alloxan monohydrate. After eight weeks following the establishment of periodontal defects in all rats, the ligation was removed and 3 rats were scarified as negative control (group 1). The remaining animals were divided into three group based on treatment applied following mucoperiosteal flap surgery. Group 2 received saline treatment only, group 3 received doxycycline periostat (1.5 mg/kg/day) for 3 weeks, and group 4 received aminoguanidine (7.3 mmol/kg) for 3 weeks. The fasting glucose level was measured weekly post operatively. After 21 days all rats were sacrificed. Three anterior parts of the mandible of each group was prepared for histopathological examination and two parts were prepared for SEM. Results Aminoguanidine treated group (group 4) showed statistically significant increased new bone formation, higher number of osteoblasts and decrease osteoclasts number, resorptive lacunae and existing inflammatory cell infiltration as compared to positive control group (group 2) (P<0.05). Doxycycline was also effective in reducing bone loss as documental by histopathological study. Conclusion The present study showed that aminoguanidine was significantly effective in reducing alveolar bone loss and can modify the

  6. Serial Reconstruction and Montaging from Large-Field Electron Microscope Tomograms

    PubMed Central

    Phan, Sébastien; Terada, Masako; Lawrence, Albert

    2010-01-01

    Electron microscope tomography [1] has been proven as an essential technique for imaging the structure of cells beyond the range of the light microscope down to the molecular level. However, because of the extreme difference in spatial scales, there is a large gap to be bridged between light and electron microscopy. Various techniques have been developed, including increasing size of the sensor arrays, serial sectioning and montaging. Data sets and reconstructions obtained by the latter techniques generate many 3D reconstructions that need to be glued together to provide information at a larger spatial scale. However, during the course of data acquisition, thin slices may become warped in optical and electron microscope preparations. We review some procedures for de-warping sections and reassembling them into larger reconstructions, and present some data from electron microscopy. PMID:19963656

  7. Pathological features of cantharidin-induced toxic cardiomyopathy: lack of correlation between electron-microscopic and histopathologic myocardial damage.

    PubMed

    Friesen, J M; Ferris, J A; Rabkin, S S; Fung, H Y

    1979-01-01

    Electron-microscopic evidence of the cardiotoxic effects of cantharidin administered to rabbits was observed. No correlation was found between the electron-microscopic changes and the light-microscopic features as assessed by special histological stains. The reasons for this are discussed.

  8. Electron microscopic examination of wastewater biofilm formation and structural components.

    PubMed Central

    Eighmy, T T; Maratea, D; Bishop, P L

    1983-01-01

    This research documents in situ wastewater biofilm formation, structure, and physiochemical properties as revealed by scanning and transmission electron microscopy. Cationized ferritin was used to label anionic sites of the biofilm glycocalyx for viewing in thin section. Wastewater biofilm formation paralleled the processes involved in marine biofilm formation. Scanning electron microscopy revealed a dramatic increase in cell colonization and growth over a 144-h period. Constituents included a variety of actively dividing morphological types. Many of the colonizing bacteria were flagellated. Filaments were seen after primary colonization of the surface. Transmission electron microscopy revealed a dominant gram-negative cell wall structure in the biofilm constituents. At least three types of glycocalyces were observed. The predominant glycocalyx possessed interstices and was densely labeled with cationized ferritin. Two of the glycocalyces appeared to mediate biofilm adhesion to the substratum. The results suggest that the predominant glycocalyx of this thin wastewater biofilm serves, in part, to: (i) enclose the bacteria in a matrix and anchor the biofilm to the substratum and (ii) provide an extensive surface area with polyanionic properties. Images PMID:6881965

  9. Construction of a new type of low-energy scanning electron microscope with atomic resolution

    NASA Astrophysics Data System (ADS)

    Eastham, D. A.; Edmondson, P.; Donnelly, S.; Olsson, E.; Svensson, K.; Bleloch, A.

    2009-05-01

    We describe a new type of scanning electron microscope which works by directly imaging the electron field-emission sites on a nanotip. Electrons are extracted from the nanotip through a nanoscale aperture, accelerated in a high electric field and focussed to a spot using a microscale einzel lens. If the whole microscope (accelerating section and lens) and the focal length are both restricted in size to below 10 microns, then computer simulations show that the effects of aberration are extremely small and it is possible to have a system with approximately unit magnification, at electron energies as low as 300 eV. Thus a typical emission site of 1 nm diameter will produce an image of the same size and an atomic emission site with give a resolution of 0.1-0.2 nm (1-2 Å), and because the beam is not allowed to expand beyond 100nm in diameter the depth of field is large and the contribution to the beam spot size from chromatic aberrations is less than 0.02 nm (0.2 Å) for 500 eV electrons. Since it is now entirely possible to make stable atomic sized emitters (nanopyramids) it is expected that this instrument will have atomic resolution. Furthermore the brightness of the beam is determined only by the field-emission and can be up to a million times larger than in a typical (high-energy) electron microscope. The construction of this microscope, based on using a nanotip electron source which is mounted on a nanopositioner so that it can be positioned at the correct point adjacent to the microscope, entrance aperture, is described. In this geometry the scanning is achieved by moving the sample using piezos. Two methods for the construction of the microscope column are reviewed and the results of preliminary tests are described. The advantages of this low energy, bright-beam, electron microscope with atomic resolution are described. It can be used in either scanning mode or diffraction mode. The major advantage over existing microscopes is that because it works at very low

  10. The carotid siphon: a scanning electron microscope assessment of its embolic potential.

    PubMed

    Saunders, F W; Shedden, P

    1985-08-01

    The role of the carotid siphon as a source of embolic material has had limited morphological or clinical study. The morphologic data available suggests that the siphon plays only a small role in embolic cerebrovascular disease. Clinical studies, however, suggest that it has a significant ischemic potential. To clarify this apparent discrepancy, we have designed a scanning electron microscope study of the carotid siphon. Eighty percent of the specimens from the carotid bifurcation and 30% of the siphon specimens showed evidence of damaged endothelium with attached red cell and platelet debris. The embolic potential of the siphon is estimated to be between 1/3 to 1/2 that of the carotid bifurcation. This supports the most recent clinical studies.

  11. High-resolution imaging in the scanning transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Pennycook, S. J.; Jesson, D. E.

    1992-03-01

    The high-resolution imaging of crystalline materials in the scanning transmission electron microscopy (STEM) is reviewed with particular emphasis on the conditions under which an incoherent image can be obtained. It is shown that a high-angle annular detector can be used to break the coherence of the imaging process, in the transverse plane through the geometry of the detector, or in three dimensions if multiphonon diffuse scattering is detected. In the latter case, each atom can be treated as a highly independent source of high-angle scattering. The most effective fast electron states are therefore tightly bound s-type Bloch states. Furthermore, they add constructively for each incident angle in the coherent STEM probe, so that s states are responsible for practically the entire image contrast. Dynamical effects are largely removed, and almost perfect incoherent imaging is achieved. S states are relatively insensitive to neighboring strings, so that incoherent imaging is maintained for superlattice and interfaces, and supercell calculations are unnecessary. With an optimum probe profile, the incoherent image represents a direct image of the crystal projection, with compositional sensitivity built in through the strong dependence of the scattering cross sections on atomic number Z.

  12. Contrast and decay of cathodoluminescence from phosphor particles in a scanning electron microscope.

    PubMed

    den Engelsen, Daniel; Harris, Paul G; Ireland, Terry G; Fern, George R; Silver, Jack

    2015-10-01

    Cathodoluminescence (CL) studies are reported on phosphors in a field emission scanning electron microscope (FESEM). ZnO: Zn and other luminescent powders manifest a bright ring around the periphery of the particles: this ring enhances the contrast. Additionally, particles resting on top of others are substantially brighter than underlying ones. These phenomena are explained in terms of the combined effects of electrons backscattered out of the particles, together with light absorption by the substrate. The contrast is found to be a function of the particle size and the energy of the primary electrons. Some phosphor materials exhibit a pronounced comet-like structure at high scan rates in a CL-image, because the particle continues to emit light after the electron beam has moved to a position without phosphor material. Image analysis has been used to study the loss of brightness along the tail and hence to determine the decay time of the materials. The effect of phosphor saturation on the determination of decay times by CL-microscopy was also investigated.

  13. Transmission electron microscope cells for use with liquid samples

    DOEpatents

    Khalid, Waqas; Alivisatos, Paul A.; Zettl, Alexander K.

    2016-08-09

    This disclosure provides systems, methods, and devices related to transmission electron microscopy cells for use with liquids. In one aspect a device includes a substrate, a first graphene layer, and a second graphene layer. The substrate has a first surface and a second surface. The first surface defines a first channel, a second channel, and an outlet channel. The first channel and the second channel are joined to the outlet channel. The outlet channel defines a viewport region forming a though hole in the substrate. The first graphene layer overlays the first surface of the substrate, including an interior area of the first channel, the second channel, and the outlet channel. The second graphene layer overlays the first surface of the substrate, including open regions defined by the first channel, the second channel, and the outlet channel.

  14. Ultrafast magnetization dynamics: Microscopic electronic configurations and ultrafast spectroscopy

    NASA Astrophysics Data System (ADS)

    Locht, I. L. M.; Di Marco, I.; Garnerone, S.; Delin, A.; Battiato, M.

    2015-08-01

    We provide an approach for the identification of the electronic and magnetic configurations of ferromagnetic Fe after an ultrafast decrease or increase of the magnetization. The model is based on the well-grounded assumption that, after an ultrafast variation of the magnetization, the system achieves a partial thermal equilibrium. With statistical arguments we show that the magnetic configurations are qualitatively different in the case of reduced or increased magnetization. The predicted magnetic configurations are then used to compute the dielectric response at the 3 p (M ) absorption edge, which is directly related to the changes observed in the experimental T-MOKE data. The good qualitative agreement between theory and experiment offers a substantial support for the validity of the model, and to the very existence of an ultrafast increase of the magnetization.

  15. Comparative evaluation of efficacy of EndoVac irrigation system to Max-I probe in removing smear layer in apical 1 mm and 3 mm of root canal: An in vitro scanning electron microscope study

    PubMed Central

    Dua, Ankur; Dua, Deepti

    2015-01-01

    Background: The purpose of this study was to compare the efficacy of EndoVac irrigation system and side-vented closed ended needle (Max-I probe) in removing smear layer from root canals at 1 mm and 3 mm from working length using ProTaper rotary instrumentation. Materials and Methods: A total of 50 freshly extracted maxillary central incisors were randomly divided into two groups after complete cleaning and shaping with ProTaper rotary files. In one group, final irrigation was performed with EndoVac system while in other group, final irrigation was done with a 30 gauge Max-I probe. 3% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetracetic acid were used as final irrigants in all teeth. During instrumentation, 1 ml of 3% NaOCl was used for irrigation after each rotary instrument in the similar manner as in final irrigation. After instrumentation and irrigation, teeth were sectioned longitudinally into buccal and palatal halves and viewed under scanning electron microscope for evaluation of smear layer. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U-test. (P < 0.05) Results: At 3 mm level, there was no significant difference between two groups. At 1 mm level, EndoVac group showed significantly better smear layer removal compared with Max-I probe (P = 0.0001). Conclusion: EndoVac system results in better smear layer removal at 1 mm from working length when compared to Max-I probe irrigation. PMID:25709673

  16. A plastic scintillator film for an electron beam-excitation assisted optical microscope

    NASA Astrophysics Data System (ADS)

    Inami, Wataru; Fukuta, Masahiro; Masuda, Yuriko; Nawa, Yasunori; Ono, Atsushi; Lin, Sheng; Kawata, Yoshimasa; Terakawa, Susumu

    2015-04-01

    A plastic scintillator film for use in an electron beam excitation-assisted (EXA) optical microscope is characterized. The thin film scatters an incident electron beam weakly and generates high intensity nanoscale luminescence excited by the beam spot. For high spatial resolution and signal to noise, an EXA microscope requires a thin high-efficiency scintillator film. Homogeneous plastic scintillators with thicknesses ranging from 60 to 2800 nm were fabricated on silicon nitride via spin coating. The emission intensity was examined as a function of film thickness and the accelerating voltage of the incident electron beam. The emission wavelength can be tuned by changing scintillator materials in the film matrix. To demonstrate a plastic scintillator film performance with an EXA microscope, time-lapse images of yeast cells were acquired.

  17. Tip alignment system in a sextupole-corrected scanning transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Ruan, Shengyang; Kapp, Oscar H.

    1993-03-01

    Tip alignment and replacement in ultrahigh vacuum field-emission electron microscopes is traditionally a time-consuming endeavor. A convenient autodrive system for the 200 kV scanning transmission electron microscope was developed to facilitate the alignment of field-emission tips, thus saving a great deal of experimenter time. Under computer control, a series of automatic electrical and mechanical processes are initiated to systematically adjust various parameters to effect passage of the electron beam through the various apertures of the microscope column. The task of ``finding the beam'' is thus performed automatically. In this process the tip holder is moved in a raster parallel to the first anode. Feedback from various detectors placed throughout the column direct the positioning of the tip for optimal alignment. This process is routinely performed in about 45 min.

  18. Microscopic and Macroscopic Studies on Resistance Responses to Daylily Rust

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infection process of Puccinia hemerocallidis, the causal agent of daylily rust, and resistance responses in eight daylily cultivars were studied macroscopically and microscopically. After germination of urediniospores, appressoria formed at the tip of germ tubes and penetrated through stomatal openi...

  19. Sub-Angstrom Low Voltage Performance of a Monochromated, Aberration-Corrected Transmission Electron Microscope

    PubMed Central

    Bell, David C.; Russo, Christopher J.; Benner, Gerd

    2011-01-01

    Lowering the electron energy in the transmission electron microscope allows for a significant improvement in contrast of light elements, and reduces knock-on damage for most materials. If low-voltage electron microscopes are defined as those with accelerating voltages below 100 kV, the introduction of aberration correctors and monochromators to the electron microscope column enables Ångstrom-level resolution, which was previously reserved for higher voltage instruments. Decreasing electron energy has three important advantages: 1) knock-on damage is lower, which is critically important for sensitive materials such as graphene and carbon nanotubes; 2) cross sections for electron-energy-loss spectroscopy increase, improving signal-to-noise for chemical analysis; 3) elastic scattering cross sections increase, improving contrast in high-resolution, zero-loss images. The results presented indicate that decreasing the acceleration voltage from 200 kV to 80 kV in a monochromated, aberration-corrected microscope enhances the contrast while retaining sub-angstrom resolution. These improvements in low-voltage performance are expected to produce many new results and enable a wealth of new experiments in materials science. PMID:20598206

  20. Intracellular forms of pox viruses as shown by the electron microscope (Vaccinia, Ectromelia, Molluscum Contagiosum).

    PubMed

    GAYLORD, W H; MELNICK, J L

    1953-08-01

    The intracellular development of three pox viruses has been studied with the electron microscope using thin sections of infected tissue. Cells infected with vaccinia, ectromelia, and molluscum contagiosum viruses all form developmental bodies preliminary to the production of mature virus. Developmental bodies, believed to be virus precursors, are round to oval, slightly larger than mature virus particles, less dense to electrons, and have a more varied morphology. It is suggested as a working hypothesis that the process of maturation of a virus particle takes place as follows. In the earliest form the developmental bodies appear as hollow spheres, imbedded in a very dense cytoplasmic mass constituting an inclusion body, or in a less dense matrix near the nucleus in cells without typical inclusion bodies. The spheres become filled with a homogeneous material of low electron density. A small, dense granule appears in each developmental body and grows in size at the expense of the low density material. Following growth of the granule, particles are found with the dimensions of mature virus and having complex internal structure resembling bars or dumbells. Mature virus is ovoid and very dense to electrons. An "empty" interior may be found within its thick walls.

  1. Electron microscopic structure of human umbilical cord blood lipoproteins

    SciTech Connect

    Forte, T.M.; Davis, P.A.; Nordhausen, R.W.; Glueck, C.J.

    1982-01-01

    Neonatal VLDL, LDL, HDL/sub 2/ and HDL/sub 3/ were isolated from umbilical cord blood by preparative ultracentrifugation and analyzed by electron microscopy. Cord blood VLDL were round particles that were heterogeneous in size, mean diameter 49.5 +/- 10.3 nm. This size was very similar to that of the normal adult population. Cord blood LDL had a mean diameter of 25.9 +/- 3.4 nm. Most LDL particles were round in profile, but there was always a small fraction of particles which had flattened sides and formed short, linear aggregates. Cord blood HDL/sub 3/ were homogeneous round particles indistinguishable from those of the adult. HDL/sub 2/ from cord blood had a mean diameter of 11.5 +/- 1.7 nm and are larger than the adult population. The HDL/sub 2/ were characterized by the presence of small amounts of rectangular-shaped structures, 14.0 by 10.0 nm in size. These latter particles are enriched in the density fraction d 1.095 g/ml and are unique to the cord blood HDL. The presence of these unusual particles suggests that cord blood HDL may transport lipids in a somewhat different fashion from that of normal adult HDL.

  2. In situ fatigue loading stage inside scanning electron microscope

    NASA Technical Reports Server (NTRS)

    Telesman, Jack; Kantzos, Peter; Brewer, David

    1988-01-01

    A fatigue loading stage inside a scanning electron microscopy (SEM) was developed. The stage allows dynamic and static high-magnification and high-resolution viewing of the fatigue crack initiation and crack propagation processes. The loading stage is controlled by a closed-loop servohydraulic system. Maximum load is 1000 lb (4450 N) with test frequencies ranging up to 30 Hz. The stage accommodates specimens up to 2 inches (50 mm) in length and tolerates substantial specimen translation to view the propagating crack. At room temperature, acceptable working resolution is obtainable for magnifications ranging up to 10,000X. The system is equipped with a high-temperature setup designed for temperatures up to 2000 F (1100 C). The signal can be videotaped for further analysis of the pertinent fatigue damage mechanisms. The design allows for quick and easy interchange and conversion of the SEM from a loading stage configuration to its normal operational configuration and vice versa. Tests are performed entirely in the in-situ mode. In contrast to other designs, the NASA design has greatly extended the life of the loading stage by not exposing the bellows to cyclic loading. The loading stage was used to investigate the fatigue crack growth mechanisms in the (100)-oriented PWA 1480 single-crystal, nickel-based supperalloy. The high-magnification observations revealed the details of the crack growth processes.

  3. Electron microscopic identification of hydrogen peroxide detected in fixed human polymorphonuclear leukocytes during phagocytosis.

    PubMed

    Moriguchi, Keiichi; Ohno, Norikazu

    2014-01-01

    Polymorphonuclear leukocytes (PMNs) engaged in phagocytosis produce reactive oxygen species (ROS), such as those that occur in an activated NADPH oxidase reaction, to eliminate ingested microorganisms. The translocation of NADPH oxidase components to produce antimicrobial free radicals from the vesicles to the phagosomes may be important. Hydrogen peroxide (H2O2) derived from O2- has been observed by electron microscopy using a cerium method. However, 2'-7'-dichlorofluorescin diacetate can also detect H2O2 through fluorescence. The main objective of the present study was to measure the H2O2-dependent fluorescence of PMNs after opsonized zymosan A (OPZ) phagocytosis using a microplate reader under different fixation conditions, including 0.5, 1, and 10% glutaraldehyde (GA) individually for 1, 5, 10, or 30 min. An additional objective was to visualize, through the use of electron microscopic cytochemistry, the process of H2O2 generation in OPZ phagocytic fixed PMNs. The fixed PMNs showed that the largest fluorescent value was produced by a concentration of 0.5% GA for all fixation times. This suggested that the fixation of PMNs with a high concentration of GA inhibited phagocytosis and produced ROS. In the fixed PMNs, electron microscopic results showed that after 1 min of mixing, some PMNs attached to particles and exhibited mild deposits in their secretory vesicles. When PMNs engulfed particles, free radical-producing vesicles had enhanced reaction deposits 10 min later and fused to the phagosomal membrane, releasing numerous free radicals into the lumen. Time-dependent H2O2 production was enhanced in the secretory vesicles, some of which were fused exactly to the phagosome membranes.

  4. Quantitative Nanostructure Characterization Using Atomic Pair Distribution Functions Obtained From Laboratory Electron Microscopes

    SciTech Connect

    Abeykoon M.; Billinge S.; Malliakas, C.D.; Juhas, P.; Bozin, E.S.; Kanatzidis, M.G.

    2012-05-01

    Quantitatively reliable atomic pair distribution functions (PDFs) have been obtained from nanomaterials in a straightforward way from a standard laboratory transmission electron microscope (TEM). The approach looks very promising for making electron derived PDFs (ePDFs) a routine step in the characterization of nanomaterials because of the ubiquity of such TEMs in chemistry and materials laboratories. No special attachments such as energy filters were required on the microscope. The methodology for obtaining the ePDFs is described as well as some opportunities and limitations of the method.

  5. Study of surface plasmons with a scanning acoustic microscope

    SciTech Connect

    Bereiter-Hahn, J; Blase, C; Lozovik, Yurii E; Nazarov, Maksim M; Shkurinov, A P

    2003-05-31

    A new technique for investigating the surface plasmons by means of a scanning acoustic microscope is proposed. Within this technique, the surface electromagnetic wave (plasmon polariton) is excited by laser radiation on one side of a metal film, while a scanning acoustic microscope excites surface acoustic waves on the other side of the film. Obtained for the first time, the acoustic images of plasmons, propagating on the grating surface, demonstrate the possibility of studying the plasmon wave field distribution by means of a scanning acoustic microscope. (nonlinear optical phenomena)

  6. Correcting for 3D distortion when using backscattered electron detectors in a scanning electron microscope.

    PubMed

    Proctor, Jacob M

    2009-01-01

    A variable pressure scanning electron microscope (VPSEM) can produce a topographic surface relief of a physical object under examination, in addition to its two-dimensional (2D) image. This topographic surface relief is especially helpful when dealing with porous rock because it may elucidate the pore-space structure as well as grain shape and size. Whether the image accurately reproduces the physical object depends on the management of the hardware, acquisition, and postprocessing. Two problems become apparent during testing: (a) a topographic surface relief of a precision ball bearing is distorted and does not correspond to the physical dimensions of the actual sphere and (b) an image of a topographic surface relief of a Berea sandstone is geometrically tilted and topographically distorted even after standard corrections are applied. The procedure presented here is to ensure the veracity of the image, and includes: (a) adjusting the brightness and contrast levels originally provided by the manufacturer and (b) tuning the amplifiers of the backscatter detector plates to be equal to each other, and producing zero voltage when VPSEM is idle. This procedure is tested and verified on the said two physical samples. SCANNING 31: 59-64, 2009. (c) 2009 Wiley Periodicals, Inc.

  7. Nanoscale Energy-Filtered Scanning Confocal Electron Microscopy Using a Double-Aberration-Corrected Transmission Electron Microscope

    SciTech Connect

    Wang Peng; Behan, Gavin; Kirkland, Angus I.; Nellist, Peter D.; Takeguchi, Masaki; Hashimoto, Ayako; Mitsuishi, Kazutaka; Shimojo, Masayuki

    2010-05-21

    We demonstrate that a transmission electron microscope fitted with two spherical-aberration correctors can be operated as an energy-filtered scanning confocal electron microscope. A method for establishing this mode is described and initial results showing 3D chemical mapping with nanoscale sensitivity to height and thickness changes in a carbon film are presented. Importantly, uncorrected chromatic aberration does not limit the depth resolution of this technique and moreover performs an energy-filtering role, which is explained in terms of a combined depth and energy-loss response function.

  8. Ion and electron beam nanofabrication of the which-way double-slit experiment in a transmission electron microscope

    SciTech Connect

    Frabboni, Stefano

    2010-12-27

    We have realized a which-way experiment closely resembling the original Feynman's proposal exploiting focused ion beam milling to prepare two nanoslits and electron beam induced deposition to grow, selectively over one of them, electron transparent layers of low atomic number amorphous material to realize a which-way detector for high energy electrons. By carrying out the experiment in an electron microscope equipped with an energy filter, we show that the inelastic scattering of electron transmitted through amorphous layers of different thicknesses provides the control of the dissipative interaction process responsible for the localization phenomena which cancels out the interference effects.

  9. X-ray microscope for solidification studies

    NASA Technical Reports Server (NTRS)

    Kaukler, William

    1995-01-01

    This report covers the second 6 month period for the year March 1, 1994 to February 28, 1995. The material outlined in this semi-annual report continues from the previous semi-annual report. The Fein Focus Inc. x-ray source was delivered in September and coincides with the beginning of the second 6 month effort. As a result, and as outlined in the statement of work, this period was dedicated to the evaluation, testing and calibration of the x-ray source. In addition, in this period the modeling effort was continued and extended by the Tiger series of Monte-Carlo simulation programs for photon and electron interactions with materials obtained from the Oak Ridge RISC Library. Some further calculations were also made with the absorption model.

  10. Tissue response to titanium implant using scanning electron microscope

    PubMed Central

    Nautiyal, Vijay P.; Mittal, Ankur; Agarwal, Amit; Pandey, Anupam

    2013-01-01

    Most of the surgeons now use titanium miniplates because of its biocompatibility and corrosion resistant properties; studies have shown that these titanium particles are released in the surrounding tissues causing tissue necrosis and if these implants are placed for a long period, the adverse effect of these implants are more severe. It therefore necessitates a study to find out whether these titanium particles are released into surrounding tissues from titanium miniplates used for maxillofacial fractures so that we could use these implants, that is, bone plates and screws with more confidence. PMID:24163546

  11. Electron tomography of HEK293T cells using scanning electron microscope-based scanning transmission electron microscopy.

    PubMed

    You, Yun-Wen; Chang, Hsun-Yun; Liao, Hua-Yang; Kao, Wei-Lun; Yen, Guo-Ji; Chang, Chi-Jen; Tsai, Meng-Hung; Shyue, Jing-Jong

    2012-10-01

    Based on a scanning electron microscope operated at 30 kV with a homemade specimen holder and a multiangle solid-state detector behind the sample, low-kV scanning transmission electron microscopy (STEM) is presented with subsequent electron tomography for three-dimensional (3D) volume structure. Because of the low acceleration voltage, the stronger electron-atom scattering leads to a stronger contrast in the resulting image than standard TEM, especially for light elements. Furthermore, the low-kV STEM yields less radiation damage to the specimen, hence the structure can be preserved. In this work, two-dimensional STEM images of a 1-μm-thick cell section with projection angles between ±50° were collected, and the 3D volume structure was reconstructed using the simultaneous iterative reconstructive technique algorithm with the TomoJ plugin for ImageJ, which are both public domain software. Furthermore, the cross-sectional structure was obtained with the Volume Viewer plugin in ImageJ. Although the tilting angle is constrained and limits the resulting structural resolution, slicing the reconstructed volume generated the depth profile of the thick specimen with sufficient resolution to examine cellular uptake of Au nanoparticles, and the final position of these nanoparticles inside the cell was imaged.

  12. Monitoring Synaptic Vesicle Protein Sorting with Enhanced Horseradish Peroxidase in the Electron Microscope.

    PubMed

    Schikorski, Thomas

    2016-01-01

    Protein sorting is the fundamental cellular process that creates and maintains cell organelles and subcellular structures. The synaptic vesicle (SV) is a unique cell organelle that contains a plethora of specific SV proteins and its protein composition is crucial for its function. Thus understanding the mechanisms that sort proteins to SVs and other cell organelles is central to neuroscience and cell biology.While in the past protein sorting was studied in the fluorescence and confocal microscope, we here present a protocol that reveals SV protein trafficking and sorting in the electron microscope (EM). The protocol exploits tagging SV proteins with a new genetically encoded label for EM: enhanced horseradish peroxidase (eHRP). eHRP gained its high sensitivity through direct evolution of its catalytic activity and is detectable in the EM and LM after expression in neurons and other mammalian cells. The protocol describes the use of eHRP, labeling of SVs in cultured hippocampal neurons, and analysis via serial section reconstruction. PMID:27515091

  13. Electron microscopic morphometry of isolated rat brain porosome complex.

    PubMed

    Zhvania, Mzia G; Japaridze, Nadezhda J; Qsovreli, Mariam G; Okuneva, Vera G; Surmava, Arkadi G; Lordkipanidze, Tamar G

    2015-11-01

    Porosomes are the universal secretory portals at the cell plasma membrane where secretory vesicles dock and transiently fuse via the kiss-and-run mechanism of cellular secretion, to release intravesicular cargo to the outside of the cell. During last two decades discovery of porosome and a great volume of work from different laboratories provide molecular insights on the structure, function, and composition of the porosome complex, especially the neuronal porosome. In rat neurons 12-17 nm cup-shaped lipoprotein porosomes present at presynaptic membrane. They possess a central plug and sometimes are with docked synaptic vesicles. Although earlier studies have greatly progressed our understanding of the morphology and the proteome and limited lipidome of the neuronal porosome complex, the current study was carried out to determine the morphology of the bare protein backbone of the neuronal porosome complex. Results from our study demonstrate that although the eight-fold symmetry of the immunoisolated porosome is maintained, and the central plug is preserved in the isolated structures, there is a loss in the average size of the porosome complex, possibly due to a loss of lipids from the complex. PMID:26119463

  14. Raman spectroscopic and scanning electron microscopic analysis of a novel biological colonisation of volcanic rocks

    NASA Astrophysics Data System (ADS)

    Jorge Villar, Susana E.; Edwards, Howell G. M.; Benning, Liane G.

    2006-09-01

    A novel type of colonisation of a basaltic rock, collected on the Arctic island of Svalbard, Norway, during the AMASE expedition in 2004, was characterised using Raman spectroscopy and Scanning Electron Microscopy (SEM). The sample contains two different types of extremophile communities, one occurring behind a radial white crystallisation and the other occurring inside a dark vacuole. Several types of minerals and microbial colonies have been identified by both Raman spectroscopy and SEM analyses. It is the first time that photosynthetic communities have been documented to colonise the inside of dark basaltic rocks. Our discovery has important implications for planetary exploration because it extends the analytical capability and our understanding of microbial rock colonisations to subaerial volcanic outcrops and has wide implications towards the search for life in extraterrestrial planets. In this work we also demonstrate that the use of different laser wavelengths for Raman spectroscopic studies and complementary microscopic analysis are critical for a comprehensive organic and inorganic compound identification.

  15. Progress on PEEM3 - An Aberration Corrected X-Ray PhotoemissionElectron Microscope at the ALS

    SciTech Connect

    MacDowell, Alastair A.; Feng, J.; DeMello, A.; Doran, A.; Duarte,R.; Forest, E.; Kelez, N.; Marcus, M.A.; Miller, T.; Padmore, H.A.; Raoux, S.; Robin, D.; Scholl, A.; Schlueter, R.; Schmid, P.; Stohr, J.; Wan, W.; Wei, D.H.; Wu, Y.

    2006-05-20

    A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed and built at the Advanced Light Source (ALS). An electron mirror combined with a much-simplified magnetic dipole separator is to be used to provide simultaneous correction of spherical and chromatic aberrations. It is installed on an elliptically polarized undulator (EPU) beamline, and will be operated with very high spatial resolution and high flux to study the composition, structure, electric and magnetic properties of complex materials. The instrument has been designed and is described. The instrumental hardware is being deployed in 2 phases. The first phase is the deployment of a standard PEEM type microscope consisting of the standard linear array of electrostatic electron lenses. The second phase will be the installation of the aberration corrected upgrade to improve resolution and throughput. This paper describes progress as the instrument enters the commissioning part of the first phase.

  16. Electron microscopic observations on the epithelium of ram seminal vesicles.

    PubMed Central

    Plöen, L

    1980-01-01

    The ultrastructure of the secretory cells of the ram seminal vesicle was studied on material fixed by immersion or by vascular perfusion. The signs of apocrine secretion seen after immersion fixation did not appear after perfusion fixation and are therefore interpreted as artefacts. Instead, vacuoles with a granule in them were seen. Such vacuoles were observed in the Golgi apparatus and in the apical cytoplasm. Further indications of merocrine secretion were also found. It therefore appears that protein secretion in the ram seminal vesicle follows the typical pattern of serous glands. The possibility that fructose is extruded with the protein as the vacuoles open at the luminal cell surface is discussed. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:7410195

  17. Direct-write liquid phase transformations with a scanning transmission electron microscope.

    PubMed

    Unocic, Raymond R; Lupini, Andrew R; Borisevich, Albina Y; Cullen, David A; Kalinin, Sergei V; Jesse, Stephen

    2016-08-25

    The highly energetic electron beam (e-beam) in a scanning transmission electron microscope (STEM) can induce local changes in the state of matter, ranging from knock-on and atomic movement, to amorphization/crystallization, and to localized chemical/electrochemical reactions. To date, fundamental studies of e-beam induced phenomena and practical applications have been limited by conventional STEM e-beam rastering modes that allow only for uniform e-beam exposures. Here, an automated liquid phase nanolithography method has been developed that enables the direct writing of nanometer scaled features within microfabricated liquid cells. An external e-beam control system, connected to the scan coils of an aberration-corrected STEM, is used to precisely control the position, dwell time, and scan rate of a sub-nanometer STEM probe. Site-specific locations in a sealed liquid cell containing an aqueous solution of H2PdCl4 are irradiated to deposit palladium nanocrystals onto silicon nitride membranes in a highly controlled manner. The threshold electron dose required for the radiolytic deposition of metallic palladium has been determined, the influence of electron dose on the nanolithographically patterned feature size and morphology is explored, and a feedback-controlled monitoring method for active control of the nanofabricated structures through STEM detector signal monitoring is proposed. This approach enables fundamental studies of electron beam induced interactions with matter in liquid cells and opens new pathways to fabricate nanostructures with tailored architectures and chemistries via shape-controlled nanolithographic patterning from liquid-phase precursors. PMID:27510435

  18. Direct-write liquid phase transformations with a scanning transmission electron microscope.

    PubMed

    Unocic, Raymond R; Lupini, Andrew R; Borisevich, Albina Y; Cullen, David A; Kalinin, Sergei V; Jesse, Stephen

    2016-08-25

    The highly energetic electron beam (e-beam) in a scanning transmission electron microscope (STEM) can induce local changes in the state of matter, ranging from knock-on and atomic movement, to amorphization/crystallization, and to localized chemical/electrochemical reactions. To date, fundamental studies of e-beam induced phenomena and practical applications have been limited by conventional STEM e-beam rastering modes that allow only for uniform e-beam exposures. Here, an automated liquid phase nanolithography method has been developed that enables the direct writing of nanometer scaled features within microfabricated liquid cells. An external e-beam control system, connected to the scan coils of an aberration-corrected STEM, is used to precisely control the position, dwell time, and scan rate of a sub-nanometer STEM probe. Site-specific locations in a sealed liquid cell containing an aqueous solution of H2PdCl4 are irradiated to deposit palladium nanocrystals onto silicon nitride membranes in a highly controlled manner. The threshold electron dose required for the radiolytic deposition of metallic palladium has been determined, the influence of electron dose on the nanolithographically patterned feature size and morphology is explored, and a feedback-controlled monitoring method for active control of the nanofabricated structures through STEM detector signal monitoring is proposed. This approach enables fundamental studies of electron beam induced interactions with matter in liquid cells and opens new pathways to fabricate nanostructures with tailored architectures and chemistries via shape-controlled nanolithographic patterning from liquid-phase precursors.

  19. Nanoscale imaging of whole cells using a liquid enclosure and a scanning transmission electron microscope.

    PubMed

    Peckys, Diana B; Veith, Gabriel M; Joy, David C; de Jonge, Niels

    2009-12-14

    Nanoscale imaging techniques are needed to investigate cellular function at the level of individual proteins and to study the interaction of nanomaterials with biological systems. We imaged whole fixed cells in liquid state with a scanning transmission electron microscope (STEM) using a micrometer-sized liquid enclosure with electron transparent windows providing a wet specimen environment. Wet-STEM images were obtained of fixed E. coli bacteria labeled with gold nanoparticles attached to surface membrane proteins. Mammalian cells (COS7) were incubated with gold-tagged epidermal growth factor and fixed. STEM imaging of these cells resulted in a resolution of 3 nm for the gold nanoparticles. The wet-STEM method has several advantages over conventional imaging techniques. Most important is the capability to image whole fixed cells in a wet environment with nanometer resolution, which can be used, e.g., to map individual protein distributions in/on whole cells. The sample preparation is compatible with that used for fluorescent microscopy on fixed cells for experiments involving nanoparticles. Thirdly, the system is rather simple and involves only minimal new equipment in an electron microscopy (EM) laboratory.

  20. Nanoscale Imaging of Whole Cells Using a Liquid Enclosure and a Scanning Transmission Electron Microscope

    PubMed Central

    Peckys, Diana B.; Veith, Gabriel M.; Joy, David C.; de Jonge, Niels

    2009-01-01

    Nanoscale imaging techniques are needed to investigate cellular function at the level of individual proteins and to study the interaction of nanomaterials with biological systems. We imaged whole fixed cells in liquid state with a scanning transmission electron microscope (STEM) using a micrometer-sized liquid enclosure with electron transparent windows providing a wet specimen environment. Wet-STEM images were obtained of fixed E. coli bacteria labeled with gold nanoparticles attached to surface membrane proteins. Mammalian cells (COS7) were incubated with gold-tagged epidermal growth factor and fixed. STEM imaging of these cells resulted in a resolution of 3 nm for the gold nanoparticles. The wet-STEM method has several advantages over conventional imaging techniques. Most important is the capability to image whole fixed cells in a wet environment with nanometer resolution, which can be used, e.g., to map individual protein distributions in/on whole cells. The sample preparation is compatible with that used for fluorescent microscopy on fixed cells for experiments involving nanoparticles. Thirdly, the system is rather simple and involves only minimal new equipment in an electron microscopy (EM) laboratory. PMID:20020038

  1. Three-dimensional machining of carbon nanotube forests using water-assisted scanning electron microscope processing

    SciTech Connect

    Rajabifar, Bahram; Maschmann, Matthew R.; Kim, Sanha; Hart, A. John; Slinker, Keith; Ehlert, Gregory J.

    2015-10-05

    We demonstrate that vertically aligned carbon nanotubes (CNTs) can be precisely machined in a low pressure water vapor ambient using the electron beam of an environmental scanning electron microscope. The electron beam locally damages the irradiated regions of the CNT forest and also dissociates the water vapor molecules into reactive species including hydroxyl radicals. These species then locally oxidize the damaged region of the CNTs. The technique offers material removal capabilities ranging from selected CNTs to hundreds of cubic microns. We study how the material removal rate is influenced by the acceleration voltage, beam current, dwell time, operating pressure, and CNT orientation. Milled cuts with depths between 0–100 microns are generated, corresponding to a material removal rate of up to 20.1 μm{sup 3}/min. The technique produces little carbon residue and does not disturb the native morphology of the CNT network. Finally, we demonstrate direct machining of pyramidal surfaces and re-entrant cuts to create freestanding geometries.

  2. Quantifying Transient States in Materials with the Dynamic Transmission Electron Microscope

    SciTech Connect

    Campbell, G; LaGrange, T; Kim, J; Reed, B; Browning, N

    2009-09-21

    The Dynamic Transmission Electron Microscope (DTEM) offers a means of capturing rapid evolution in a specimen through in-situ microscopy experiments by allowing 15 ns electron micrograph exposure times. The rapid exposure time is enabled by creating a burst of electrons at the emitter by ultraviolet pulsed laser illumination. This burst arrives a specified time after a second laser initiates the specimen reaction. The timing of the two Q-switched lasers is controlled by high-speed pulse generators with a timing error much less than the pulse duration. Both diffraction and imaging experiments can be performed, just as in a conventional TEM. The brightness of the emitter and the total current control the spatial and temporal resolutions. We have demonstrated 7 nm spatial resolution in single 15 ns pulsed images. These single-pulse imaging experiments have been used to study martensitic transformations, nucleation and crystallization of an amorphous metal, and rapid chemical reactions. Measurements have been performed on these systems that are possible by no other experimental approaches currently available.

  3. Three-dimensional machining of carbon nanotube forests using water-assisted scanning electron microscope processing

    NASA Astrophysics Data System (ADS)

    Rajabifar, Bahram; Kim, Sanha; Slinker, Keith; Ehlert, Gregory J.; Hart, A. John; Maschmann, Matthew R.

    2015-10-01

    We demonstrate that vertically aligned carbon nanotubes (CNTs) can be precisely machined in a low pressure water vapor ambient using the electron beam of an environmental scanning electron microscope. The electron beam locally damages the irradiated regions of the CNT forest and also dissociates the water vapor molecules into reactive species including hydroxyl radicals. These species then locally oxidize the damaged region of the CNTs. The technique offers material removal capabilities ranging from selected CNTs to hundreds of cubic microns. We study how the material removal rate is influenced by the acceleration voltage, beam current, dwell time, operating pressure, and CNT orientation. Milled cuts with depths between 0-100 microns are generated, corresponding to a material removal rate of up to 20.1 μm3/min. The technique produces little carbon residue and does not disturb the native morphology of the CNT network. Finally, we demonstrate direct machining of pyramidal surfaces and re-entrant cuts to create freestanding geometries.

  4. Strain mapping at the nanoscale using precession electron diffraction in transmission electron microscope with off axis camera

    SciTech Connect

    Vigouroux, M. P.; Delaye, V.; Bernier, N.; Lafond, D.; Audoit, G.; Bertin, F.; Cipro, R.; Baron, T.; Martin, M.; Rouvière, J. L.; Chenevier, B.

    2014-11-10

    Precession electron diffraction is an efficient technique to measure strain in nanostructures by precessing the electron beam, while maintaining a few nanometre probe size. Here, we show that an advanced diffraction pattern treatment allows reproducible and precise strain measurements to be obtained using a default 512 × 512 DigiSTAR off-axis camera both in advanced or non-corrected transmission electron microscopes. This treatment consists in both projective geometry correction of diffraction pattern distortions and strain Delaunay triangulation based analysis. Precision in the strain measurement is improved and reached 2.7 × 10{sup −4} with a probe size approaching 4.2 nm in diameter. This method is applied to the study of the strain state in InGaAs quantum-well (QW) devices elaborated on Si substrate. Results show that the GaAs/Si mismatch does not induce in-plane strain fluctuations in the InGaAs QW region.

  5. An ultrafast electron microscope gun driven by two-photon photoemission from a nanotip cathode

    SciTech Connect

    Bormann, Reiner; Strauch, Stefanie; Schäfer, Sascha Ropers, Claus

    2015-11-07

    We experimentally and numerically investigate the performance of an advanced ultrafast electron source, based on two-photon photoemission from a tungsten needle cathode incorporated in an electron microscope gun geometry. Emission properties are characterized as a function of the electrostatic gun settings, and operating conditions leading to laser-triggered electron beams of very low emittance (below 20 nm mrad) are identified. The results highlight the excellent suitability of optically driven nano-cathodes for the further development of ultrafast transmission electron microscopy.

  6. Scanning electron microscope view of iron crystal growing on pyroxene crystal

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A scanning electron microscope photograph of a four-micron size iron crystal growing on a pyroxene crystal (calcium-magnesium-iron silicate) from the Apollo 15 Hadley-Apennino lunar landing site. The well developed crystal faces indicate that the crystal was formed from a hot vapor as the rock was cooling.

  7. Characterization of calcium crystals in Abelia using x-ray diffraction and electron microscopes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Localization, chemical composition, and morphology of calcium crystals in leaves and stems of Abelia mosanensis and A. ×grandiflora were analyzed with a variable pressure scanning electron microscope (VP-SEM) equipped with an X-ray diffraction system, low temperature SEM (LT-SEM) and a transmission ...

  8. Practical application of HgI2 detectors to a space-flight scanning electron microscope

    NASA Technical Reports Server (NTRS)

    Bradley, J. G.; Conley, J. M.; Albee, A. L.; Iwanczyk, J. S.; Dabrowski, A. J.

    1989-01-01

    Mercuric iodide X-ray detectors have been undergoing tests in a prototype scanning electron microscope system being developed for unmanned space flight. The detector program addresses the issues of geometric configuration in the SEM, compact packaging that includes separate thermoelectric coolers for the detector and FET, X-ray transparent hermetic encapsulation and electrical contacts, and a clean vacuum environment.

  9. The microscopic world: A demonstration of electron microscopy for younger students

    NASA Technical Reports Server (NTRS)

    Horton, Linda L.

    1992-01-01

    The purpose is to excite students about the importance of scientific investigation and demonstrate why they should look at things in greater detail, extending beyond superficial examination. The topics covered include: microscopy, scanning electron microscopes, high magnification, and the scientific method.

  10. Transmission electron microscope specimen preparation for exploring the buried interfaces in plan view.

    PubMed

    Radnóczi, G Z; Pécz, B

    2006-12-01

    A relatively easy and convenient process for the preparation of transmission electron microscope specimens of buried interfaces is described. The method is based on the alignment and realignment of the specimen rotation centre during ion milling. The ion-milling time interval in which good samples are obtained is substantially extended in this way.

  11. Modeling a Miniaturized Scanning Electron Microscope Focusing Column - Lessons Learned in Electron Optics Simulation

    NASA Technical Reports Server (NTRS)

    Loyd, Jody; Gregory, Don; Gaskin, Jessica

    2016-01-01

    This presentation discusses work done to assess the design of a focusing column in a miniaturized Scanning Electron Microscope (SEM) developed at the NASA Marshall Space Flight Center (MSFC) for use in-situ on the Moon-in particular for mineralogical analysis. The MSFC beam column design uses purely electrostatic fields for focusing, because of the severe constraints on mass and electrical power consumption imposed by the goals of lunar exploration and of spaceflight in general. The resolution of an SEM ultimately depends on the size of the focused spot of the scanning beam probe, for which the stated goal here is a diameter of 10 nanometers. Optical aberrations are the main challenge to this performance goal, because they blur the ideal geometrical optical image of the electron source, effectively widening the ideal spot size of the beam probe. In the present work the optical aberrations of the mini SEM focusing column were assessed using direct tracing of non-paraxial rays, as opposed to mathematical estimates of aberrations based on paraxial ray-traces. The geometrical ray-tracing employed here is completely analogous to ray-tracing as conventionally understood in the realm of photon optics, with the major difference being that in electron optics the lens is simply a smoothly varying electric field in vacuum, formed by precisely machined electrodes. Ray-tracing in this context, therefore, relies upon a model of the electrostatic field inside the focusing column to provide the mathematical description of the "lens" being traced. This work relied fundamentally on the boundary element method (BEM) for this electric field model. In carrying out this research the authors discovered that higher accuracy in the field model was essential if aberrations were to be reliably assessed using direct ray-tracing. This led to some work in testing alternative techniques for modeling the electrostatic field. Ultimately, the necessary accuracy was attained using a BEM

  12. Solar Flare Track Exposure Ages in Regolith Particles: A Calibration for Transmission Electron Microscope Measurements

    NASA Technical Reports Server (NTRS)

    Berger, Eve L.; Keller, Lindsay P.

    2015-01-01

    Mineral grains in lunar and asteroidal regolith samples provide a unique record of their interaction with the space environment. Space weathering effects result from multiple processes including: exposure to the solar wind, which results in ion damage and implantation effects that are preserved in the rims of grains (typically the outermost 100 nm); cosmic ray and solar flare activity, which result in track formation; and impact processes that result in the accumulation of vapor-deposited elements, impact melts and adhering grains on particle surfaces. Determining the rate at which these effects accumulate in the grains during their space exposure is critical to studies of the surface evolution of airless bodies. Solar flare energetic particles (mainly Fe-group nuclei) have a penetration depth of a few millimeters and leave a trail of ionization damage in insulating materials that is readily observable by transmission electron microscope (TEM) imaging. The density of solar flare particle tracks is used to infer the length of time an object was at or near the regolith surface (i.e., its exposure age). Track measurements by TEM methods are routine, yet track production rate calibrations have only been determined using chemical etching techniques [e.g., 1, and references therein]. We used focused ion beam-scanning electron microscope (FIB-SEM) sample preparation techniques combined with TEM imaging to determine the track density/exposure age relations for lunar rock 64455. The 64455 sample was used earlier by [2] to determine a track production rate by chemical etching of tracks in anorthite. Here, we show that combined FIB/TEM techniques provide a more accurate determination of a track production rate and also allow us to extend the calibration to solar flare tracks in olivine.

  13. Naturally weathered feldspar surfaces in the Navajo Sandstone aquifer, Black Mesa, Arizona: Electron microscopic characterization

    USGS Publications Warehouse

    Zhu, Chen; Veblen, D.R.; Blum, A.E.; Chipera, S.J.

    2006-01-01

    Naturally weathered feldspar surfaces in the Jurassic Navajo Sandstone at Black Mesa, Arizona, was characterized with high-resolution transmission and analytical electron microscope (HRTEM-AEM) and field emission gun scanning electron microscope (FEG-SEM). Here, we report the first HRTEM observation of a 10-nm thick amorphous layer on naturally weathered K-feldspar in currently slightly alkaline groundwater. The amorphous layer is probably deficient in K and enriched in Si. In addition to the amorphous layer, the feldspar surfaces are also partially coated with tightly adhered kaolin platelets. Outside of the kaolin coatings, feldspar grains are covered with a continuous 3-5 ??m thick layer of authigenic smectite, which also coats quartz and other sediment grains. Authigenic K-feldspar overgrowth and etch pits were also found on feldspar grains. These characteristics of the aged feldspar surfaces accentuate the differences in reactivity between the freshly ground feldspar powders used in laboratory experiments and feldspar grains in natural systems, and may partially contribute to the commonly observed apparent laboratory-field dissolution rate discrepancy. At Black Mesa, feldspars in the Navajo Sandstone are dissolving at ???105 times slower than laboratory rate at comparable temperature and pH under far from equilibrium condition. The tightly adhered kaolin platelets reduce the feldspar reactive surface area, and the authigenic K-feldspar overgrowth reduces the feldspar reactivity. However, the continuous smectite coating layer does not appear to constitute a diffusion barrier. The exact role of the amorphous layer on feldspar dissolution kinetics depends on the origin of the layer (leached layer versus re-precipitated silica), which is uncertain at present. However, the nanometer thin layer can be detected only with HRTEM, and thus our study raises the possibility of its wide occurrence in geological systems. Rate laws and proposed mechanisms should consider the

  14. Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope

    PubMed Central

    Hieckmann, Ellen; Nacke, Markus; Allardt, Matthias; Bodrov, Yury; Chekhonin, Paul; Skrotzki, Werner; Weber, Jörg

    2016-01-01

    Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared. PMID:27285177

  15. Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope.

    PubMed

    Hieckmann, Ellen; Nacke, Markus; Allardt, Matthias; Bodrov, Yury; Chekhonin, Paul; Skrotzki, Werner; Weber, Jörg

    2016-01-01

    Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared.

  16. Development of wavelength-dispersive soft X-ray emission spectrometers for transmission electron microscopes--an introduction of valence electron spectroscopy for transmission electron microscopy.

    PubMed

    Terauchi, Masami; Koike, Masato; Fukushima, Kurio; Kimura, Atsushi

    2010-01-01

    Two types of wavelength-dispersive soft X-ray spectrometers, a high-dispersion type and a conventional one, for transmission electron microscopes were constructed. Those spectrometers were used to study the electronic states of valence electrons (bonding electrons). Both spectrometers extended the acceptable energy regions to higher than 2000 eV. The best energy resolution of 0.08 eV was obtained for an Al L-emission spectrum by using the high-dispersion type spectrometer. By using the spectrometer, C K-emission of carbon allotropes, Cu L-emission of Cu(1-x)Zn(x) alloys and Pt M-emission spectra were presented. The FWHM value of 12 eV was obtained for the Pt Malpha-emission peak. The performance of the conventional one was also presented for ZnS and a section specimen of a multilayer device. W-M and Si-K emissions were clearly resolved. Soft X-ray emission spectroscopy based on transmission electron microscopy (TEM) has an advantage for obtaining spectra from a single crystalline specimen with a defined crystal setting. As an example of anisotropic soft X-ray emission, C K-emission spectra of single crystalline graphite with different crystal settings were presented. From the spectra, density of states of pi- and sigma-bondings were separately derived. These results demonstrated a method to analyse the electronic states of valence electrons of materials in the nanometre scale based on TEM. PMID:20371492

  17. Towards native-state imaging in biological context in the electron microscope

    PubMed Central

    Weston, Anne E.; Armer, Hannah E. J.

    2009-01-01

    Modern cell biology is reliant on light and fluorescence microscopy for analysis of cells, tissues and protein localisation. However, these powerful techniques are ultimately limited in resolution by the wavelength of light. Electron microscopes offer much greater resolution due to the shorter effective wavelength of electrons, allowing direct imaging of sub-cellular architecture. The harsh environment of the electron microscope chamber and the properties of the electron beam have led to complex chemical and mechanical preparation techniques, which distance biological samples from their native state and complicate data interpretation. Here we describe recent advances in sample preparation and instrumentation, which push the boundaries of high-resolution imaging. Cryopreparation, cryoelectron microscopy and environmental scanning electron microscopy strive to image samples in near native state. Advances in correlative microscopy and markers enable high-resolution localisation of proteins. Innovation in microscope design has pushed the boundaries of resolution to atomic scale, whilst automatic acquisition of high-resolution electron microscopy data through large volumes is finally able to place ultrastructure in biological context. PMID:19916039

  18. Design and implementation of a fs-resolved transmission electron microscope based on thermionic gun technology

    NASA Astrophysics Data System (ADS)

    Piazza, L.; Masiel, D. J.; LaGrange, T.; Reed, B. W.; Barwick, B.; Carbone, Fabrizio

    2013-09-01

    In this paper, the design and implementation of a femtosecond-resolved ultrafast transmission electron microscope is presented, based on a thermionic gun geometry. Utilizing an additional magnetic lens between the electron acceleration and the nominal condenser lens system, a larger percentage of the electrons created at the cathode are delivered to the specimen without degrading temporal, spatial and energy resolution significantly, while at the same time maintaining the femtosecond temporal resolution. Using the photon-induced near field electron microscopy effect (PINEM) on silver nanowires the cross-correlation between the light and electron pulses was measured, showing the impact of the gun settings and initiating laser pulse duration on the electron bunch properties. Tuneable electron pulses between 300 fs and several ps can be obtained, and an overall energy resolution around 1 eV was achieved.

  19. Nonlinearities in sedimentation: a microscopic study

    NASA Astrophysics Data System (ADS)

    Aurongzeb, Deeder M.

    2005-04-01

    Effect of temperature and surface tension on surface during sedimentation is studied using atomic force microscopy. Effects of surface tension is incorporated by using ˜1 mm radius water droplets. Surface tension of water droplet directed the deposition of dissolved particles around the perimeter of the droplet; leaving almost hollow circle in the middle with light deposition due to the particles being close to the surface. Evaporating shallow water solutions left random salt structures on the surface. Growth exponents are calculated along with the fractal dimension. For sedimentation process in shallow water (depth of ˜2 mm), a transition is observed from continuum model (1.88±0.2) to KPZ (0.406±0.082) universality class around ˜1 μm at room temperature. For droplets evaporation, turbulent (multi-affine) to self-affine transition is observed. Fractal dimensions (FD) for the droplets are found to be between one and two. The FD values are consistent with the fact that competing nonlinear terms are present in the system.

  20. Environmental scanning electron microscope (ESEM) evaluation of crystal and plaque formation associated with biocorrosion.

    PubMed

    Geiger, S L; Ross, T J; Barton, L L

    1993-08-01

    The biofilm attributed to Desulfovibrio vulgaris growing in the presence of ferrous metals was examined with an environmental scanning electron microscope. This novel microscope produced images of iron sulfide colloids and other iron containing structures that had not been reported previously. A plaque composed of iron sulfide enveloped the surface of the corroding metal while crystals containing magnesium, iron, sulfur, and phosphorus were present in the culture where corrosion was in progress. A structure resembling the tubercule found in aerobic corrosion was observed on stainless steel undergoing biocorrosion and the elements present in this structure included sulfur, iron, chloride, calcium, potassium, and chromium.

  1. Preparation of human formalin-fixed brain slices for electron microscopic investigations.

    PubMed

    Krause, Martin; Brüne, Martin; Theiss, Carsten

    2016-07-01

    Ultra-structural analysis of human post-mortem brain tissue is important for investigations into the pathomechanism of neuropsychiatric disorders, especially those lacking alternative models of studying human-specific morphological features. For example, Von Economo Neurons (VENs) mainly located in the anterior cingulate cortex and in the anterior part of the insula, which seem to play a role in a variety of neuropsychiatric conditions, including frontotemporal dementia, autism and schizophrenia, can hardly be studied in nonhuman animals. Accordingly, little is known about the ultra-structural alterations of these neurons, though important research using qualitative stereological methods has revealed that protein expression of the VENs assigns them a role in immune function. Formaldehyde, which is the most common fixative in human pathology, interferes with the immunoreactivity of the tissue, possibly leading to unreliable results. Therefore, a method for ultra-structural investigations independent of antigenic properties of the fixated tissue is needed. Here, we propose an approach using electron microscopy to examine cytoskeletal structures, synapses and mitochondria in these cells. We also show that our methodology is able to keep tissue consumption to a minimum, while still allowing for the specimens to be handled with ease by using agar embedded slices in contrast to blocks for the embedding procedure. Accordingly, a stepwise protocol utilising 60μm thick human post mortem brain sections for electron microscopic ultra-structural investigations is presented. PMID:27136748

  2. Novel scanning electron microscope bulge test technique integrated with loading function

    SciTech Connect

    Li, Chuanwei; Xie, Huimin E-mail: xiehm@mail.tsinghua.edu.cn; Liu, Zhanwei E-mail: xiehm@mail.tsinghua.edu.cn

    2014-10-15

    Membranes and film-on-substrate structures are critical elements for some devices in electronics industry and for Micro Electro Mechanical Systems devices. These structures are normally at the scale of micrometer or even nanometer. Thus, the measurement for the mechanical property of these membranes poses a challenge over the conventional measurements at macro-scales. In this study, a novel bulge test method is presented for the evaluation of mechanical property of micro thin membranes. Three aspects are discussed in the study: (a) A novel bulge test with a Scanning Electron Microscope system realizing the function of loading and measuring simultaneously; (b) a simplified Digital Image Correlation method for a height measurement; and (c) an imaging distortion correction by the introduction of a scanning Moiré method. Combined with the above techniques, biaxial modulus as well as Young's modulus of the polyimide film can be determined. Besides, a standard tensile test is conducted as an auxiliary experiment to validate the feasibility of the proposed method.

  3. Observation of spatial distribution of vacancy defects in semiconductor by positron microscope and electron beam induced current measurement

    NASA Astrophysics Data System (ADS)

    Maekawa, M.; Kawasuso, A.

    2013-06-01

    A complementary study of vacancy defects in Si substrates by using scanning positron microscope (SPM) and electron beam induced current (EBIC) method were demonstrated for the same samples and in the same chamber. Both the S parameter and EBIC contrast were found to be enhanced in the regions containing vacancy defects introduced by ion implantation. That is, the SPM provides a criterion if the spatially resolved carrier recombination centres by the EBIC method are originating from vacancy defects or not.

  4. Rocksalt ZnO nanocrystal formation by beam irradiation of wurtzite ZnO in a transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Lee, Sung Bo

    2016-10-01

    Under ambient conditions, ZnO crystallizes in a hexagonal wurtzite structure, but undergoes a phase transformation into a rocksalt structure with increasing hydrostatic pressure. However, in the present study, I have successfully demonstrated that intense beam irradiation of a wurtzite ZnO specimen in a transmission electron microscope produces nanoparticles of rocksalt ZnO as well as wurtzite ZnO, suggesting that the application of pressures is not a necessary condition for the formation of rocksalt ZnO.

  5. Effect of CO2 laser on Class V cavities of human molar teeth under a scanning electron microscope.

    PubMed

    Watanabe, I; Lopes, R A; Brugnera, A; Katayama, A Y; Gardini, A E

    1996-01-01

    The purpose of this study was to evaluate the effects of CO2 laser on dentin of class V cavities of extracted human molar teeth using a scanning electron microscope. SEM showed a smooth area with concentric lines formed by melting with subsequent recrystallization of dentin, areas of granulation, vitrified surface, numerous cracks, and irregular areas of descamative dentin. These data indicate that CO2 laser (4 and 6 watts) produces dentin alterations and limit its clinical applications.

  6. Scanning image detection (SID) system for conventional transmission electron microscope (CTEM) images.

    PubMed

    Tanji, T; Tomita, M; Kobayashi, H

    1990-08-01

    A new image detection system has been developed to display transmission electron microscope (TEM) images on a CRT without a video camera system. Deflection coils placed in both the upper space of an objective lens and in the lower space of the first intermediate lens scan a small electron probe simultaneously. The electrical signal acquired through an improved scintillator and a photomultiplier is synchronized with the scanning signal and displayed in a similar fashion to a conventional scanning TEM (STEM) instrument. A preliminary system using a 100 kV conventional TEM (CTEM) equipped with a hairpin-type electron gun, produced an image with a spatial resolution of 1 nm.

  7. Analysis with electron microscope of multielement samples using pure element standards

    DOEpatents

    King, Wayne E.

    1987-01-01

    A method and modified analytical electron microscope for determining the concentration of elements in a multielement sample by exposing samples with differing thicknesses for each element to a beam of electrons, simultaneously measuring the electron dosage and x-ray intensities for each sample of element to determine a "K.sub.AB " value to be used in the equation ##EQU1## where I is intensity and C is concentration for elements A and B, and exposing the multielement sample to determine the concentrations of the elements in the sample.

  8. Analysis with electron microscope of multielement samples using pure element standards

    DOEpatents

    King, W.E.

    1986-01-06

    This disclosure describes a method and modified analytical electron microscope for determining the concentration of elements in a multielement sample by exposing samples with differing thicknesses for each element to a beam of electrons. Simultaneously the electron dosage and x-ray intensities are measured for each sample of element to determine a ''K/sub AB/'' value to be used in the equation (I/sub A/I/sub B/) = K/sub AB/ (C/sub A//C/sub B/), where I is intensity and C is concentration for elements A and B. The multielement sample is exposed to determine the concentrations of the elements in the sample.

  9. Note: Long-range scanning tunneling microscope for the study of nanostructures on insulating substrates

    SciTech Connect

    Molina-Mendoza, Aday J.; Rodrigo, José G.; Rubio-Bollinger, Gabino; Island, Joshua; Burzuri, Enrique; Zant, Herre S. J. van der; Agraït, Nicolás

    2014-02-15

    The scanning tunneling microscope (STM) is a powerful tool for studying the electronic properties at the atomic level, however, it is of relatively small scanning range and the fact that it can only operate on conducting samples prevents its application to study heterogeneous samples consisting of conducting and insulating regions. Here we present a long-range scanning tunneling microscope capable of detecting conducting micro and nanostructures on insulating substrates using a technique based on the capacitance between the tip and the sample and performing STM studies.

  10. Method and apparatus for a high-resolution three dimensional confocal scanning transmission electron microscope

    DOEpatents

    de Jonge, Niels [Oak Ridge, TN

    2010-08-17

    A confocal scanning transmission electron microscope which includes an electron illumination device providing an incident electron beam propagating in a direction defining a propagation axis, and a precision specimen scanning stage positioned along the propagation axis and movable in at least one direction transverse to the propagation axis. The precision specimen scanning stage is configured for positioning a specimen relative to the incident electron beam. A projector lens receives a transmitted electron beam transmitted through at least part of the specimen and focuses this transmitted beam onto an image plane, where the transmitted beam results from the specimen being illuminated by the incident electron beam. A detection system is placed approximately in the image plane.

  11. Enhanced contrast separation in scanning electron microscopes via a suspended-thin sample approach.

    PubMed

    Ji, Yuan; Wang, Li; Guo, Zhenxi; Wei, Bin; Zhao, Jie; Wang, Xiaodong; Zhang, Yinqi; Sui, Manling; Han, Xiaodong

    2014-11-01

    A suspended-thin-sample (STS) approach for signal selection and contrast separation is developed in scanning electron microscopes with commonly used primary beam energies and traditional detectors. Topography contrast, electron channeling contrast and composition contrast are separated and largely enhanced from suspended thin samples of several hundred nanometers in thickness, which is less than the escape depth of backscattered electrons. This imaging technique enables to detect relatively pure secondary electron and elastic backscattered electron singles, whereas suppress multiple inelastic scattering effects. The provided contrast features are different from those of bulk samples, which are largely mixed with inelastic scattering effects. The STS imaging concept and method could be expected to have more applications in distinguishing materials of nanostructures, multilayers, compounds and composites, as well as in SEM-based electron backscatter diffraction, cathodoluminesence, and x-ray microanalysis.

  12. Conductive resins improve charging and resolution of acquired images in electron microscopic volume imaging

    PubMed Central

    Nguyen, Huy Bang; Thai, Truc Quynh; Saitoh, Sei; Wu, Bao; Saitoh, Yurika; Shimo, Satoshi; Fujitani, Hiroshi; Otobe, Hirohide; Ohno, Nobuhiko

    2016-01-01

    Recent advances in serial block-face imaging using scanning electron microscopy (SEM) have enabled the rapid and efficient acquisition of 3-dimensional (3D) ultrastructural information from a large volume of biological specimens including brain tissues. However, volume imaging under SEM is often hampered by sample charging, and typically requires specific sample preparation to reduce charging and increase image contrast. In the present study, we introduced carbon-based conductive resins for 3D analyses of subcellular ultrastructures, using serial block-face SEM (SBF-SEM) to image samples. Conductive resins were produced by adding the carbon black filler, Ketjen black, to resins commonly used for electron microscopic observations of biological specimens. Carbon black mostly localized around tissues and did not penetrate cells, whereas the conductive resins significantly reduced the charging of samples during SBF-SEM imaging. When serial images were acquired, embedding into the conductive resins improved the resolution of images by facilitating the successful cutting of samples in SBF-SEM. These results suggest that improving the conductivities of resins with a carbon black filler is a simple and useful option for reducing charging and enhancing the resolution of images obtained for volume imaging with SEM. PMID:27020327

  13. Evaluation of the dentinal wall adaptation ability of MTA Fillapex using stereo electron microscope

    PubMed Central

    Demiriz, Levent; Koçak, Mustafa Murat; Koçak, Sibel; Sağlam, Baran Can; Türker, Sevinç Aktemur

    2016-01-01

    Background: An ideal root canal obturation requires a complete dentinal wall adaptation of sealer and Gutta-percha combinations without any gap formations. Aims: The aim of the study was to evaluate the dentinal wall adaptation ability of MTA Fillapex root canal sealer using stereo electron microscope (SEM). Methods: Twenty-four, single-rooted, human maxillary incisor teeth were used. All canals were prepared with a rotary nickel–titanium (Ni–Ti) instrument to a size F3 file. Teeth divided into two equal groups and one of the experimental groups was filled with AH Plus, and the other group was filled with MTA Fillapex using Gutta-percha single cone as a core material. The roots were prepared for SEM evaluation, and serial scanning electron photomicrographs were taken at ×50, ×100, ×500, and ×1000 magnifications. The gaps between the root canal sealer and canal walls were detected and measured in coronal, middle, and apical thirds. For each section, the highest value among the detected gap formations was recorded. Statistical Analysis: Mann–Whitney U-test, Freidman, and Wilcoxon tests were used. Results: The statistical analysis showed no significant difference between two sealers in terms of gap formation (P > 0.05). Conclusions: MTA Fillapex has a similar dentinal wall adaptation ability as AH Plus does. PMID:27217633

  14. A Comparative Study of Microscopic Images Captured by a Box Type Digital Camera Versus a Standard Microscopic Photography Camera Unit

    PubMed Central

    Desai, Nandini J.; Gupta, B. D.; Patel, Pratik Narendrabhai

    2014-01-01

    Introduction: Obtaining images of slides viewed by a microscope can be invaluable for both diagnosis and teaching.They can be transferred among technologically-advanced hospitals for further consultation and evaluation. But a standard microscopic photography camera unit (MPCU)(MIPS-Microscopic Image projection System) is costly and not available in resource poor settings. The aim of our endeavour was to find a comparable and cheaper alternative method for photomicrography. Materials and Methods: We used a NIKON Coolpix S6150 camera (box type digital camera) with Olympus CH20i microscope and a fluorescent microscope for the purpose of this study. Results: We got comparable results for capturing images of light microscopy, but the results were not as satisfactory for fluorescent microscopy. Conclusion: A box type digital camera is a comparable, less expensive and convenient alternative to microscopic photography camera unit. PMID:25478350

  15. Skeletal growth phases of the cold-water coral Lophelia pertusa shown by scanning electron microscope and electron backscatter diffraction

    NASA Astrophysics Data System (ADS)

    Mouchi, Vincent; Vonlanthen, Pierre; Verrecchia, Eric P.; Crowley, Quentin G.

    2016-04-01

    Lophelia pertusa is a cold-water coral, which may form reefs by the association of multiple coralites within which a polyp lives. Each individual polyp builds an aragonite skeleton by an initial phase of early mineralization (traditionally referred to as centres of calcification) from which aragonite fibres grow in thickening deposits. The skeleton wall features successive optically opaque and translucent bands previously attributed to different regimes of growth as either uniform in crystal orientation (translucent bands) or with a chaotic organization (opaque bands). The processes involved in any organizational changes are still unknown. Microlayers in the coral wall, which represent separate periods of skeletal growth, have been recently identified and described. These growth patterns are readily visible under scanning electron microscope (SEM) after etching in dilute formic acid, but they do not necessarily form continuously visible structures. Here we present high quality SEM images and electron backscatter diffraction (EBSD) maps to study aragonite fibre orientation across the wall of L. pertusa. Both microlayers and opaque and translucent bands are compared to the crystallographic orientation of the aragonite fibres. EBSD maps and SEM images indicate that aragonite fibres do not exhibit a chaotic orientation, even in opaque bands. The absence of continuity of microlayers is partially explained by an association of multiple crystallographic preferred orientations of aragonite fibres. In the case of L. pertusa, careful textural characterisation is necessary prior to elemental or isotope analysis in order to select a skeletal transect representing a linear and continuous time period.

  16. Compact Video Microscope Imaging System Implemented in Colloid Studies

    NASA Technical Reports Server (NTRS)

    McDowell, Mark

    2002-01-01

    Long description Photographs showing fiber-optic light source, microscope and charge-coupled discharge (CCD) camera head connected to camera body, CCD camera body feeding data to image acquisition board in PC, and Cartesian robot controlled via PC board. The Compact Microscope Imaging System (CMIS) is a diagnostic tool with intelligent controls for use in space, industrial, medical, and security applications. CMIS can be used in situ with a minimum amount of user intervention. This system can scan, find areas of interest in, focus on, and acquire images automatically. Many multiple-cell experiments require microscopy for in situ observations; this is feasible only with compact microscope systems. CMIS is a miniature machine vision system that combines intelligent image processing with remote control. The software also has a user-friendly interface, which can be used independently of the hardware for further post-experiment analysis. CMIS has been successfully developed in the SML Laboratory at the NASA Glenn Research Center and adapted for use for colloid studies and is available for telescience experiments. The main innovations this year are an improved interface, optimized algorithms, and the ability to control conventional full-sized microscopes in addition to compact microscopes. The CMIS software-hardware interface is being integrated into our SML Analysis package, which will be a robust general-purpose image-processing package that can handle over 100 space and industrial applications.

  17. Quantum coherent optical phase modulation in an ultrafast transmission electron microscope.

    PubMed

    Feist, Armin; Echternkamp, Katharina E; Schauss, Jakob; Yalunin, Sergey V; Schäfer, Sascha; Ropers, Claus

    2015-05-14

    Coherent manipulation of quantum systems with light is expected to be a cornerstone of future information and communication technology, including quantum computation and cryptography. The transfer of an optical phase onto a quantum wavefunction is a defining aspect of coherent interactions and forms the basis of quantum state preparation, synchronization and metrology. Light-phase-modulated electron states near atoms and molecules are essential for the techniques of attosecond science, including the generation of extreme-ultraviolet pulses and orbital tomography. In contrast, the quantum-coherent phase-modulation of energetic free-electron beams has not been demonstrated, although it promises direct access to ultrafast imaging and spectroscopy with tailored electron pulses on the attosecond scale. Here we demonstrate the coherent quantum state manipulation of free-electron populations in an electron microscope beam. We employ the interaction of ultrashort electron pulses with optical near-fields to induce Rabi oscillations in the populations of electron momentum states, observed as a function of the optical driving field. Excellent agreement with the scaling of an equal-Rabi multilevel quantum ladder is obtained, representing the observation of a light-driven 'quantum walk' coherently reshaping electron density in momentum space. We note that, after the interaction, the optically generated superposition of momentum states evolves into a train of attosecond electron pulses. Our results reveal the potential of quantum control for the precision structuring of electron densities, with possible applications ranging from ultrafast electron spectroscopy and microscopy to accelerator science and free-electron lasers.

  18. Quantum coherent optical phase modulation in an ultrafast transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Feist, Armin; Echternkamp, Katharina E.; Schauss, Jakob; Yalunin, Sergey V.; Schäfer, Sascha; Ropers, Claus

    2015-05-01

    Coherent manipulation of quantum systems with light is expected to be a cornerstone of future information and communication technology, including quantum computation and cryptography. The transfer of an optical phase onto a quantum wavefunction is a defining aspect of coherent interactions and forms the basis of quantum state preparation, synchronization and metrology. Light-phase-modulated electron states near atoms and molecules are essential for the techniques of attosecond science, including the generation of extreme-ultraviolet pulses and orbital tomography. In contrast, the quantum-coherent phase-modulation of energetic free-electron beams has not been demonstrated, although it promises direct access to ultrafast imaging and spectroscopy with tailored electron pulses on the attosecond scale. Here we demonstrate the coherent quantum state manipulation of free-electron populations in an electron microscope beam. We employ the interaction of ultrashort electron pulses with optical near-fields to induce Rabi oscillations in the populations of electron momentum states, observed as a function of the optical driving field. Excellent agreement with the scaling of an equal-Rabi multilevel quantum ladder is obtained, representing the observation of a light-driven `quantum walk' coherently reshaping electron density in momentum space. We note that, after the interaction, the optically generated superposition of momentum states evolves into a train of attosecond electron pulses. Our results reveal the potential of quantum control for the precision structuring of electron densities, with possible applications ranging from ultrafast electron spectroscopy and microscopy to accelerator science and free-electron lasers.

  19. Theoretical aspects of image formation in the aberration-corrected electron microscope.

    PubMed

    Rose, H

    2010-04-01

    The theoretical aspects of image formation in the transmission electron microscope (TEM) are outlined and revisited in detail by taking into account the elastic and inelastic scattering. In particular, the connection between the exit wave and the scattering amplitude is formulated for non-isoplanatic conditions. Different imaging modes are investigated by utilizing the scattering amplitude and employing the generalized optical theorem. A novel obstruction-free anamorphotic phase shifter is proposed which enables one to shift the phase of the scattered wave by an arbitrary amount over a large range of spatial frequencies. In the optimum case, the phase of the scattered wave and the introduced phase shift add up to -pi/2 giving negative contrast. We obtain these optimum imaging conditions by employing an aberration-corrected electron microscope operating at voltages below the knock-on threshold for atom displacement and by shifting optimally the phase of the scattered electron wave. The optimum phase shift is achieved by adjusting appropriately the constant phase shift of the phase plate and the phase shift resulting from the defocus and the spherical aberration of the corrected objective lens. The realization of this imaging mode is the aim of the SALVE project (Sub-A Low-Voltage Electron microscope).

  20. A scanning and transmission electron microscopic analysis of the cerebral aqueduct in the rabbit.

    PubMed

    Meller, S T; Dennis, B J

    1993-09-01

    An examination of the surface of the cerebral aqueduct with the scanning electron microscope revealed that the walls of the cerebral aqueduct were so heavily ciliated that most of the ependymal surface was obscured, yet certain specialized supraependymal structures could be discerned lying on (or embedded within) this matt of cilia. These structures were determined by transmission electron microscopy and Golgi analysis to be either macrophages, supraependymal neurons, dendrites from medial periaqueductal gray neurons, or axons of unknown origin. Some axons, which were found to contain vesicles, appeared to make synaptic contacts with ependymal cells. Using the transmission electron microscope, the ependymal lining was found to consist of two different cell types: normal ependymal cells and tanycytes which have a long tapering basal process that was observed to contact blood vessels or, more rarely, seemed to terminate in relation to neuronal elements. While there have been previous reports on the structure of the third and lateral ventricles in other species, there are limited reports in the rabbit. The present report is not only the first description for the rabbit, but it is the first complete scanning and transmission electron microscopic analysis of the cerebral aqueduct in any species.