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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. 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.

  5. [Electron microscopic study of forest soil].

    PubMed

    Kilbertus, G; Proth, J

    1979-08-01

    Scanning electron microscopy was used to evidence the aggregated structure of a forest soil as well as the presence of fungal hyphae external to soil aggregates. The supernatant of soil suspension in water mainly contained isolated bacteria, while ultrathin sections of aggregates frequently revealed groups of bacteria surrounded by a sheath of mucilage with adhering clay minerals on the outside. These results confirm the existence of two particular biotopes in the soil studied: one is located inside aggregates, and the other, in the inter-aggregate spaces. PMID:526892

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. Morphological abnormalities of rabbit spermatozoa studied by scanning electron microscope and quantified by light microscope.

    PubMed

    Kuzminsky, G; Fausto, A M; Morera, P

    1996-01-01

    Rabbit spermatozoa morphological abnormalities were examined to establish criteria for judging the quality of ejaculates. Ten New Zealand White bucks, aged 9 months and weighing 4.3 +/- 0.2 kg, were placed in a climatic chamber for 3 weeks at +20 degrees C and 70% RH. Sperm was collected three times a week using an artificial vagina. The use of a scanning electron microscope (from x 2000 to x 15,000) in this study produced an illustrated guide for the classification of abnormalities. Mean percentage quantitative values studied by light microscope (x 400) observation were: 18.2% total abnormalities, 2.9% head abnormalities, 13.6% tail abnormalities and 1.7% broken spermatozoa. Variability was very high (CV 35.7, 54.0, 45.3 and 32.5%, respectively); consequently, each ejaculate should be analysed before use for artificial insemination. Among the different tail abnormalities observed, the most frequent were coiled tails, 9.1%, cytoplasmic droplets, 2.4%, bent tails, 1.3% and swollen tails, 0.5%. PMID:8987108

  11. 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

  12. Coonhound paralysis. Further clinical studies and electron microscopic observations.

    PubMed

    Cummings, J F; de Lahunta, A; Holmes, D F; Schultz, R D

    1982-01-01

    Prior study of coonhound paralysis (CHP) revealed an acute polyradiculoneuritis in raccoon-hunting dogs with clinical and pathologic features resembling those of Guillain-Barré syndrome (GBS). In the present series of five cases, the clinical features were investigated with emphasis on electrodiagnostic and CSF findings, and pathologic changes were evaluated with both the light and electron microscope. The demonstration of motor nerve conduction delay and CSF albuminocytologic dissociation in affected dogs further supported the clinical similarity of CHP and GBS. As in GBS, affected roots and nerves contained mononuclear cell infiltrates, segmental myelin changes and axon degeneration. Despite these general pathologic similarities, the present study suggested that axon damage was a more consistent finding in CHP than in GBS. In contrast to ultrastructural findings in GBS, the demyelinating process in CHP did not appear dependent upon macrophages for its initiation. Swelling, separation and vesiculation of myelin occurred around axons of reduced diameter often in the absence of proximate macrophages. Macrophages, rather than initiating demyelination, appeared to be superimposed on existing damage. In this regard, the observed changes resembled those reported in galactocerebroside-induced EAN and sera-mediated in vivo demyelination. PMID:7072488

  13. Ethanol teratogenicity in mice: an electron microscopic study.

    PubMed

    Bannigan, J; Cottell, D

    1984-10-01

    In this study, the neuroepithelium (NE) cells of the mouse embryo were examined with the electron microscope at various intervals after maternal injection of 0.03 ml/g body weight 25% (v/v) ethanol on day 9 of gestation (plug day = day 1), by the intraperitoneal route. Within 1 hour of treatment, the mitochondria of the NE cells became greatly swollen but could recover. Recovery occurred in two phases: a rapid one during the second hour after treatment, followed by a more gradual one that lasted until 12 hours after treatment. About 5 hours after treatment, dying and fragmenting cells were seen in the NE of all embryos examined. The debris from this necrosis was phagocytosed by neighbouring healthy cells. Also at 5 hours after treatment there was an apparent expansion of the intercellular space of the NE and an enlargement of the apical pseudopodial processes of the NE cells. The latter two changes may have been the result of failure of energy-dependent cell fluid homeostasis consequent to mitochondrial dysfunction. All of these changes were reversed by 15 hours after treatment. Although all embryos examined had abnormalities of the NE, including cell necrosis, at 24 hours after treatment only 28% had failed to complete neural tube formation. Hence, either the degree of ethanol-induced damage varies between embryos in the same litter, or the sensitive period is so restricted that variations in stage of development within a litter can account for the lack of concordance between the presence of cellular damage and the subsequent occurrence of a neural tube defect. PMID:6495228

  14. Electron microscopic studies of magnetosomes in magnetotactic bacteria.

    PubMed

    Bazylinski, D A; Garratt-Reed, A J; Frankel, R B

    1994-04-01

    Electron microscopic studies on magnetosomes in magnetotactic bacteria have revealed much information on their composition, structure, and even the formation of their mineral phase. The mineral phases of the magnetosomes are of two general types: iron oxides and iron sulfides. Iron oxide-type magnetosomes contain particles of the ferrimagnetic mineral magnetite (Fe3O4) while the iron sulfide-type contain ferrimagnetic greigite (Fe3S4), greigite and non-magnetic pyrite (FeS2), or possibly ferrimagnetic pyrrhotite (Fe7S8). Regardless of their composition, the crystalline particles in magnetosomes have a narrow size range: approximately 35 to 120 nm. Magnetite crystals in this size range are single-magnetic-domains and confer a permanent magnetic dipole moment to the cell. The single-domain size range for greigite is not known but is probably similar to that for magnetite. The morphology of the particles in the bacterial magnetosomes appears to be species-specific. Morphologies of magnetite crystals in different species of magnetotactic bacteria include cubo-octahedra, parallelepipedal (truncated hexahedral or octahedral prisms), and tooth- or bullet-shaped (anisotropic). Morphologies of greigite particles include cubo-octahedra and rectangular prismatic. The greigite-pyrite particles are generally pleomorphic with no consistent crystalline morphology. A membrane has been shown to surround the particles in some organisms and may be involved in the formation of the crystalline phase while also providing physical constraints on the size and the shape of the crystal. These results clearly indicate that the biomineralization process involved in the bacterial magnetosome, a good example of a self-assembled structure on a nanometer scale, is highly controlled by the organism. PMID:8018991

  15. Scanning electron microscope study of Pseudomonas putida colonies.

    PubMed Central

    Shapiro, J A

    1985-01-01

    Pseudomonas putida colonies were examined by scanning electron microscope. A variety of cell morphologies, multicellular arrangements, and extracellular materials were observed in the fixed material. Different regions of a single colony showed characteristic organizations of these architectural elements. In some cases, the detailed microstructure of the fixed colony surfaces observed by scanning electron microscopy could be correlated with macroscopic patterns visualized by histochemical staining and surface relief photography of live colonies. Extracellular materials were seen to extend onto the agar surface beyond the boundaries of the cell mass, and the final structures of these materials, after fixation and desiccation, were colony specific. The significance of these features of colony microstructure for formulating hypotheses about the control of colony morphogenesis is discussed. Images PMID:4066611

  16. 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.

  17. High-speed electron microscope autoradiographic studies of diffusible compounds

    SciTech Connect

    Mizuhira, V.; Shiihashi, M.; Futaesaku, Y.

    1981-01-01

    Three important factors are necessary for successful electron microscope autoradiography (EM-ARG): good resolution, proper preparation of the radioactive isotope (RI) labeled diffusible compounds, and shortened exposure time for ARG. The resolution problem is fundamental to EM-ARG. However, unless the diffusible RI compounds have been fixed correctly in the tissues during preparation, good resolution is useless. It is also necessary to shorten the exposure time for ARG. As yet, a high-speed ARG method for electron microscopy has not been reported, although scintillation ARG methods have been applied to macro- and micro-ARG since 1960. High specific activity, a large amount of radioactivity per unit exposure for radio incorporation (incubation), and careful selection of labeled compounds that concentrate in the DNA or RNA of cell organelles may increase the sensitivity of the emulsion and shorten the exposure time for ARG. For example, labeled thymidine accumulates in nuclear DNA, /sup 3/H-SPG (Schizophyllan-produced polyglucan) is incorporated into lysosomal granules, and labeled iodine concentrates in thyroid follicles, often increasing the sensitivity of the emulsion and shortening the exposure time, but high-resolution ARG continues to be necessary, even though it requires 4 weeks or more of exposure time. Scintillation autoradiography using tritium seems unstable. We propose a new way to shorten exposure time for EM-ARG, by combining overdevelopment with coating both sides of the grid with emulsion. This method is approximately 100 times more sensitive than the conventional method, and only 4 days of exposure time are required, in contrast to the 1 month usually needed.

  18. Scanning electron microscope studies of human metaphase chromosomes

    PubMed Central

    Shemilt, L. A.; Estandarte, A. K. C.; Yusuf, M.; Robinson, I. K.

    2014-01-01

    Scanning electron microscopy (SEM) is used to evaluate potential chromosome preparations and staining methods for application in high-resolution three-dimensional X-ray imaging. Our starting point is optical fluorescence microscopy, the standard method for chromosomes, which only gives structural detail at the 200 nm scale. In principle, with suitable sample preparation protocols, including contrast enhancing staining, the surface structure of the chromosomes can be viewed at the 1 nm level by SEM. Here, we evaluate a heavy metal nucleic-acid-specific stain, which gives strong contrast in the backscattered electron signal. This study uses SEM to examine chromosomes prepared in different ways to establish a sample preparation protocol for X-rays. Secondary electron and backscattered electron signals are compared to evaluate the effectiveness of platinum-based stains used to enhance the contrast. PMID:24470422

  19. Electron Microscopic Studies of the Antigen-Antibody Complex

    PubMed Central

    Easty, G. C.; Mercer, E. H.

    1958-01-01

    Electron micrographs of the ferritin antibody (rabbit) and ferritin (horse) complex have been obtained. The high iron content of the ferritin molecule (23 per cent Fe) allows its molecules to be recognized within the particles of precipitate. Three methods of visualizing the molecular distribution have been developed: (a) small particles of the precipitated complex have been dried on to electron microscope grids and either examined directly or first shadowed with metal and then examined, (b) the precipitate has been centrifuged to a plug which was embedded and thin sections cut from it for examination, (c) the bands formed by allowing antibody and antigen to diffuse together in agar gels have been fixed, embedded and sectioned. All methods have yielded pictures of the distribution of the ferritin within the complex which are broadly similar to what might have been expected from a somewhat irregular lattice as pictured in the Marrack-Heidelberger Lattice Theory. The antibody molecules are not clearly defined but appear as a halo of low density enveloping the ferritin clusters. The distance, centre to centre, between the ferritin molecules is variable, but is, on the average, in the range 200–400 Å. This is greater than the ferritin-ferritin contact distance (100 Å) and is thought to mean that the ferritin molecules are bridged by antibody molecules as pictured in the Lattice Theory. The bands produced in the gel-diffusion test contain islands of ferritin-antibody complex. When equivalent concentrations of reagents are used a single band of precipitate is formed. When excess of either antigen or antibody is used multiple bands of precipitate are formed which contain islands of ferritin antibody complex indistinguishable from those formed in the single band at equivalent concentrations, providing direct evidence for the formation of multiple bands from a single antigen. Ferritin-ferritin contacts have been observed within the complex. Under all the conditions of

  20. [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

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Developing a Quantum Electron Microscope

    NASA Astrophysics Data System (ADS)

    Kohstall, Christoph; Klopfer, Brannon; Francis, Josh; Skulason, Gunnar; Juffmann, Thomas; Kasevich, Mark; QEM Team

    2014-03-01

    We develop a new electron microscope based on the interaction-free measurement principle. Such a Quantum Electron Microscope (QEM) may enable imaging of biological samples with radiation doses so small that they are non-lethal. The realization of the QEM will require precise control over the quantum motion of free electrons. On this poster, we discuss our approach to build a QEM including the realization of an electron resonator and an electron amplitude beam-splitter. On top of the QEM application, these developments will advance the electron analogue to photon quantum optics. Funded by the Gordon and Betty Moore Foundation.

  8. 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

  9. 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.

  10. Electron microscopic study on the interaction between normal guinea pig peritoneal macrophages and Coxiella burnetii.

    PubMed Central

    Kishimoto, R A; Veltri, B J; Canonico, P G; Shirey, F G; Walker, J S

    1976-01-01

    An electron microscopic study was conducted to explore the interaction between normal guinea pig peritoneal macrophages and phase I and II Coxeilla burnetii previously treated with either normal or immune serum. A comparison was made on the efficiency of phagocytosis and subsequent killing of rickettsiae by macrophages. Both phases of rickettsiae previously treated with normal serum multiplied within phagosomes after phagocytosis with resultant destruction of macrophages. In contrast, suspending rickettsiae in immune serum rendered them more susceptible to phagocytosis and potentiated their destruction within macrophages. Images PMID:825466

  11. 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

  12. 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.

  13. 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

  14. A scanning electron microscope technique for studying the sclerites of Cichlidogyrus.

    PubMed

    Fannes, Wouter; Vanhove, Maarten P M; Huyse, Tine; Paladini, Giuseppe

    2015-05-01

    The genus Cichlidogyrus (Monogenea: Ancyrocephalidae) includes more than 90 species, most of which are gill parasites of African cichlid fishes. Cichlidogyrus has been studied extensively in recent years, but scanning electron microscope (SEM) investigations of the isolated hard parts have not yet been undertaken. In this paper, we describe a method for isolating and scanning the sclerites of individual Cichlidogyrus worms. Twenty-year-old, formol-fixed specimens of Cichlidogyrus casuarinus were subjected to proteinase K digestion in order to release the sclerites from the surrounding soft tissues. SEM micrographs of the haptoral sclerites and the male copulatory organ are presented. The ability to digest formol-fixed specimens makes this method a useful tool for the study of historical museum collections. PMID:25828814

  15. 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

  16. 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.

  17. [Electron microscopic studies of the gill epithelium of the amphibian teleost Periophthalmus vulgaris].

    PubMed

    Welsch, U; Storch, V

    1976-01-01

    The gill epithelium of the airdwelling fish Periophthalmus vulgaris has been studied with the electron microscope. The following celltypes can be distinguished: flat covering epithelial cells, chloride cells, mucous cells, basal cells, various leucocytes as well as a specific granule containing cell which is possibly an epithelial cell. The covering epithelial cells exhibit a relatively smooth apical surface and contain in their apical half densely packed microfilaments, pinocytotic vesicles are rare. These characteristics are not to be found in water dwelling fish and possibly represent adaptations to the air containing surroundings. In the chloride cells are numerous, especially in the basal halves of the secondary lamellae. The distal parts of the secondary lamellae the barrier for the respiratory gases measures about 0,9 micrometer. The basal cells are ribosome rich replacement cells. Two types of mucous cells occur. Individual intraepithelial nerve fibres have been observed. PMID:1036346

  18. 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.

  19. 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.

  20. Seismic isolation of an electron microscope

    SciTech Connect

    Godden, W.G.; Aslam, M.; Scalise, D.T.

    1980-01-01

    A unique two-stage dynamic-isolation problem is presented by the conflicting design requirements for the foundations of an electron microscope in a seismic region. Under normal operational conditions the microscope must be isolated from ambient ground noise; this creates a system extremely vulnerable to seismic ground motions. Under earthquake loading the internal equipment forces must be limited to prevent damage or collapse. An analysis of the proposed design solution is presented. This study was motivated by the 1.5 MeV High Voltage Electron Microscope (HVEM) to be installed at the Lawrence Berkeley Laboratory (LBL) located near the Hayward Fault in California.

  1. Light and electron microscopic studies of the Gerbillus tarabuli (Thomas, 1902) Harderian gland.

    PubMed

    Saadi-Brenkia, Ouanassa; Haniche, Nadia; Bendjelloul, Mounira

    2013-01-01

    The purpose of this investigation was to study the morphological aspects of the Harderian gland in Gerbillus tarabuli. Tissues were obtained from both male and female adult Gerbillus tarabuli and processed for light and electron microscopy. The Harderian gland in gerbil is large and well developed, covered by a thin capsule, from which thin septae extend, subdividing the gland into lobes and lobules. The endpieces of the gland are tubuloalveolar, which produce a secretion of lipid character. The glandular epithelium is pseudostratified with two types of secretory cells, the type C cells are columnar in shape with large lipid vacuoles, and type P cells pyramidal and serous, they are basally located with no luminal aspect. The epithelium possesses well-developed myoepithelial cells. The wide lumina are filled with lipid vacuoles, cellular debris, and porphyrins. The Harderian gland of the gerbil has no morphologically distinct duct system; a single extraglandular excretory duct is detected. Electron microscopic examination revealed that type C cells contain large electron-light lipid vacuoles, a well and extensive reticulum endoplasmic and a large number of mitochondria. The pyramidal cells are characterized by a small number of PAS-positive granules at the basal region; these cells exhibit one or two round nuclei, many electron-dense granules, crystalloid bodies, abundant mitochondria and many ribosomes in their cytoplasm. The three mechanism of secretion are seen in the Harderian gland of Gerbillus tarabuli. In its overall characteristics, the Harderian gland of Gerbillus tarabuli conforms to the general pattern observed in rodents. However, further research will be needed to correlate the presence of cytoplasmic slashes, crystalloids bodies and glycoproteins in epithelial cells with the biology of these animals and to their functional significance. PMID:23317366

  2. 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.

  3. [Silhouettes: electron microscopic photography in bioscience].

    PubMed

    Breidbach, Olaf

    2005-06-01

    The paper describes the first attempts of biological electron microphotography. It starts with a description of the early use of electron microscopy in biology, showing that electron microscopy was used as an extension of former light microscopical studies. Thus, the pictures produced by electron microscopy are interpreted as describing the micro-texture of those structures already seen in light microscopy. That was done irrespective from the specific problems of tissue preparation for electron microscopy. The use of photography in electron microscopy is discussed in more detail. It is shown that in electron microscopy, not the preparation itself which is usually destroyed or damaged during observation in the electron microscope. Thus, biological electron microscopy can be described as a real image science. PMID:16060072

  4. Electron-microscopic study of the apical region of the toad bladder epithelial cell.

    PubMed

    Sasaki, J; Tilles, S; Condeelis, J; Carboni, J; Meiteles, L; Franki, N; Bolon, R; Robertson, C; Hays, R M

    1984-09-01

    Antidiuretic hormone (ADH) promotes fusion of cytoplasmic tubules with the luminal membrane and delivery of particles from the tubules to the membrane. The particles are believed to be the water-conducting elements in the membrane. We have employed several scanning (SEM) and transmission electron-microscopic (TEM) techniques to study the relationship of the cytoplasmic tubules to the luminal membrane and to the apical cytoskeleton of the toad bladder epithelial cell. This paper reports the results of freeze-crack SEM and tannic acid-fixed TEM studies, as well as studies with a resinless method of embedding. Freeze-cracked epithelial cells reveal that the tubules are anchored in a matrix of cytoskeleton and granules just below the luminal membrane, and many, if not all, retain their anchorage to the matrix after ADH-induced fusion. Tannic acid-fixed specimens show that the tubules in unstimulated cells lie horizontally. Fusion appears to involve an angulation of the tubules, and this may be the major mode of ADH-induced tubule movement. There are suggestions in the tannic acid sections of filamentous attachments of tubules to the surrounding cytoskeleton. In addition there are prominent microfilament bundles running down the microvilli and a dense concentration of filaments just below the luminal membrane. The presence of these filaments is confirmed in the resinless sections, and their possible role in ADH action is discussed. PMID:6433717

  5. Bacterial Biofilm Morphology on a Failing Implant with an Oxidized Surface: A Scanning Electron Microscope Study.

    PubMed

    Simion, Massimo; Kim, David M; Pieroni, Stefano; Nevins, Myron; Cassinelli, Clara

    2016-01-01

    This case report provided a unique opportunity to investigate the extent of microbiota infiltration on the oxidized implant surface that has been compromised by peri-implantitis. Scanning electron microscopic analysis confirmed the etiologic role of the bacteria on the loss of supporting structure and the difficulty in complete removal of bacterial infiltration on the implant surface. This case report emphasizes the need to perform definitive surface decontamination on failing dental implants prior to a regeneration procedure. PMID:27333005

  6. 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.

  7. [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

  8. 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.

  9. An in vitro scanning electron microscope study to evaluate the efficacy of various root conditioning agents

    PubMed Central

    Garg, Jaishree; Maurya, Rajkumar; Gupta, Ankur; Tandon, Pradeep; Gupta, Krishna Kumar; Srivastava, Amitabh

    2015-01-01

    Aim: The purpose of present study was to investigate the scanning electron microscopic alterations produced on scaled and root planed dentin surfaces after application of different etching modalities namely citric acid, tetracycline hydrochloride and ethylenediaminetetraacetic acid (EDTA). Materials and Methods: Eighty specimens of teeth were collected and categorized into four groups. In group 1, control group specimens were treated with normal saline for 3 min, group 2 specimens were treated with citric acid, group 3 specimens were treated with tetracycline hydrochloride for 3 min and group 4 specimens were treated with 15% EDTA. Results: Opening of dentinal tubules was seen in all specimens except for control group that was treated with normal saline. The total number of tubules seen was highest in citric acid group as compared to tetracycline hydrochloride and EDTA Group. The total number of patent tubule opening was highest in citric acid as compared to EDTA and tetracycline. The diameter of patent dentinal tubules in citric acid group was more than EDTA and tetracycline. Conclusion: The study showed that all the three agents were effective in removing the smear layer however number of patent and wider diameter dentinal tubules was seen in vitro best in citric acid than EDTA and then in tetracycline hydrochloride. Hence, citric acid group is more efficient than EDTA and tetracycline HCl group in removing the smear layer and in opening of number of patent dentinal tubules. PMID:26644718

  10. Electron-microscope study of lanthanum-doped lead zirconate-titanate solid solutions

    SciTech Connect

    Ishchuk, V.M.; Presnyakova, O.V.

    1985-12-01

    This paper examines the structure of specimens of lanthanumdoped lead zirconate-titanate solid solutions in the hysteresis region of the phase diagram, using transmission electron microscopy. The electron-microscopic images of PLZT ceramic of composition display an unusual diffraction contrast. An analysis of the images obtained for different orientations of the cleavages of specimens of composition indicate that the second-phase inclusions are cylindrical in the main. The authors hypothesize that the inclusions are a ferroelectric phase in an antiferroelectric matrix.

  11. 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

  12. [Development of ultrastructural changes in human cervix mucus during the ovarian cycle. Scanning electron microscope study].

    PubMed

    Chrétien, F C; Cohen, J; Psychoyos, A

    1976-01-01

    The use of the Scanning Electron Microscope has made it possible through observation to study the human cervical mucus through the various stages of the ovarian cycle, as well as to describe the significant variations of the meshed woof making up the ultrastructure during the ovarian cycle. While the slackening of the woof and the dimension of the meshes are minimal at both the beginning and end of the cycle, they reach a maximum on forteenth day. In the ovulatory period, lateral expansions from the filaments are numerous. On the other hand, median and terminal thicknesses are almost inexistant during the same period : their frequency decreases during the first part of the cycle, then increases during the luteal phase. During both the preceding and following days of ovulation, one can observe numerous twistings at the level of the filaments which probably express the relaxation and then contraction of the latter. The preparatory technique as well as the method of observation used appear reliable enough to allow a comparison of the cervical mucus ultrastructure in varied physiological, pathological and experimental situations. PMID:956619

  13. Comparative evaluation of enamel abrasivity by toothbrush and velcro: An in vitro scanning electron microscope study

    PubMed Central

    Ojha, Saroj Kumar; Javdekar, Sadashiv Bhaskar; Dhir, Sangeeta

    2015-01-01

    Context: Plaque control has been shown to be pivotal in maintaining the optimal periodontal health. Mechanical plaque control is the most popular option for establishing the optimal oral health. Toothbrushes have been the novel tool for mechanical cleansing. However, the abrasive potential of the toothbrushes on the enamel surface is an area in gray. Aims: The aim of this in vitro study is to evaluate the abrasivity of the toothbrush versus the velcro fasteners. Materials and Methods: The mounted teeth of both the groups were subjected to abrasion test, and the tooth surfaces were observed for the possible abrasions from the oscillating strokes (toothbrush) and frictional contacts (hook and loop velcro) and examined under the scanning electron microscope. Results: Comparative assessment of both velcro (hook and loop) and toothbrush bristles did not reveal any evidence of abrasion on the tooth specimens. Conclusions: Veclro fasteners are safe and qualitatively at par to the manual toothbrush for their efficacy and efficiency in teeth cleansing PMID:26229264

  14. 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

  15. 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.

  16. Light microscopic and electron microscopic histopathology of an iris microhaemangioma.

    PubMed Central

    Meades, K V; Francis, I C; Kappagoda, M B; Filipic, M

    1986-01-01

    A patient who had been observed to have an iris microhaemangioma (capillary haemangioma), confirmed on fluorescein iris angiography, came to cataract surgery. The lesion was excised at the time of surgery and submitted to light and electron microscopic study. It had the features of a hamartoma of the capillary haemangioma type, with its characteristics being specific for vessels seen in iris tissue. Images PMID:3964627

  17. Studies of the fossil dinosaur bone in the scanning electron microscope.

    PubMed

    Pawlicki, R

    1975-01-01

    A fossil dinosaur bone, 80 million years old, was subjected to investigation in the scanning microscope. The bone surfaces to be examined were prepared with appropritely modified methods used in the technique of replication in transmission electron microscopy. In the scanning microscope pictures of vascular canals were obtained. The walls of these canals were shown to be formed of collagen fibrils. Moreover, it was demonstrated that the internal surface of the canal wall is made up of bundles of collagen fibrils which run obliquely, corkscrewwise, and in the form of plexus to the long axis of tke canal; Besides, osteocytes of the dinosaur bone were isolated and pictures of their spatial structure together with characteristic points of departure of processes from the cell body were obtained. PMID:1224770

  18. 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.

  19. 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

  20. 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.

  1. Toxic effect of formaldehyde on the respiratory organs of rabbits: a light and electron microscopic study.

    PubMed

    Bansal, Neelam; Uppal, Varinder; Pathak, Devendra

    2011-07-01

    In this study, the effect of direct exposure of formaldehyde in different concentration was observed in 14 rabbits aged 3-6 months and weighing 1100-1200 g. The animals were divided into two groups with six animals in each group, and two animals were kept as control. The animals of group I were exposed to 10% formalin for 12 weeks and those of group II to 40% formalin solution for 6 weeks. After completion of the experimental periods, the animals were killed and the tissue samples were collected from the nasal cavity, trachea and lungs in 10% neutral buffered formalin and Karnovsky's fixative to examine the histological and electron microscopic changes in the organs. The mucosal cells of nasal cavity showed loss of cilia and epithelial metaplasia was observed in places. There was vascular congestion and mild subepithelial odema. The tracheal epithelium was organized with hyperchromatic nuclei. There was subepithelial odema along with lymphomononuclear cellular infiltration. There was marked emphysema evident as bulla formation of air spaces due to rupture of interalveolar septum. An increased cellularity of alveolar wall was observed, resulting in its thickening. The epithelial lining of bronchioles showed loss of mucosal folds and hyperplasia of cells along with peribronchial lymphomononuclear cellular infiltration. Thickening of wall of blood vessels was evident. Congestion and haemorrhages were observed in places. It is concluded that the histopathological changes were more remarkable in the animals exposed to 40% formaldehyde for short duration than the animals exposed to 10% formaldehyde for longer duration with a more severe effect on the upper part of the respiratory tract than the lower one. PMID:21343228

  2. Electron microscopic study on black pig skin irradiated with pulsed dye laser (504 nm)

    NASA Astrophysics Data System (ADS)

    Yasuda, Yukio; Tan, Oon T.; Kurban, Amal K.; Tsukada, Sadao

    1991-06-01

    Selective damage of epidermal pigment cells induced by 504 nm pulsed dye laser at different pulse durations and fluence on black pig skin was examined electron microscopically. Epidermal melanosomes were satisfactorily disrupted at shorter pulse duration (100 ns). Epidermal blister formation and necrosis were seen at 2 days postirradiation, and reepithelization was evident at 7 days postirradiation in all specimens. Repigmentation was evident 21 to 56 days after irradiation. Histological pigmentary incontinence was evident at 2 days and persisted until 56 days postirradiation. This phenomenon was observed more frequently in skin exposed to longer pulse duration and at low fluences. Optimal parameters required to induce epidermal melanosome disruption using the 504 nm pulsed dye laser will be discussed.

  3. Pencil lead tips: A field ion and field electron emission microscopic study

    NASA Astrophysics Data System (ADS)

    Khairnar, Rajendra S.; Dharmadhikari, C. V.; Joag, Dilip S.

    1989-06-01

    Pencil lead tips composed of graphite flakes were subjected to field ion and field emission microscopic investigations. The ion micrographs showed elongated images of ledge atoms of the graphite flakes due to uneven magnification over the layers of the flake. The gross features of the field evaporated tip surface were observed by scanning electron microscopy. The field emission pattern showed emitting lobes which displayed intensity fluctuations consisting of a combination of emission spots turning on and off randomly and a localized flicker of individual spots. These effects gave rise to noise in the emission current involving isolated spikes of rapid rise time and trains of digital pulses of constant height. The variation of noise with residual gas pressure, emission current, and temperature has also been investigated. The results are discussed in view of the microtopography of the pencil lead tips and the nature of the emitting sites on the surface.

  4. Iron partitioning between perovskite and post-perovskite: A transmission electron microscope study

    SciTech Connect

    Hirose, K.; Takafuji, N.; Shieh, S.R.; Duffy, T.S.

    2008-09-30

    The effect of iron on the post-perovskite phase transition has been controversial. We have performed direct chemical analyses of co-existing perovskite and post-perovskite that were synthesized from an (Mg{sub 0.91}Fe{sub 0.09})SiO{sub 3} bulk composition using a laser-heated diamond anvil cell at pressures above 100 GPa and temperatures of 1700-1800 K. Analysis on quenched samples was carried out using the transmission electron microscope (TEM). The results demonstrate that crystalline perovskite grains are enriched in iron compared to adjacent amorphous parts presumably converted from post-perovskite. This indicates that ferrous iron stabilizes perovskite to higher pressures. The ferrous and ferric irons are likely to have competing effects on the post-perovskite phase transition, and therefore the effect of iron may be controlled by aluminum.

  5. High-voltage electron microscope high-temperature in situ straining experiments to study dislocation dynamics in intermetallics and quasicrystals.

    PubMed

    Messerschmidt, U

    2001-07-01

    The dynamic behaviour of dislocations in several intermetallic alloys, studied by in situ straining experiments in a high-voltage electron microscope, is compared at room temperature and at high temperatures. In contrast to room temperature, the dislocations move viscously at high temperatures, which is explained by diffusion processes in the dislocation cores. In quasicrystals, the viscous dislocation motion can be interpreted by models on the cluster scale. PMID:11454156

  6. 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

  7. [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

  8. Central nervous system changes in mitochondrial encephalomyopathy: light and electron microscopic study.

    PubMed

    Mizukami, K; Sasaki, M; Suzuki, T; Shiraishi, H; Koizumi, J; Ohkoshi, N; Ogata, T; Mori, N; Ban, S; Kosaka, K

    1992-01-01

    An autopsy case of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is reported. It presented with generalized muscle atrophy, stroke-like episodes, schizophrenia-like mental disorder and progressive dementia. Serum lactate and pyruvate levels were high. In the biopsied muscles, ragged-red fibers were observed by light microscopy and aggregation of abnormal mitochondria with paracrystaline formation by electron microscopy. The most characteristic neuropathological findings were infarct-like lesions widespread in the cerebral cortex. In addition, this case showed some unusual pathological features: (1) diffuse moderate fibrillary gliosis in the whole cerebral and cerebellar white matter, which might have been due to metabolic disturbances; (2) several focal lesions with demyelination and numerous spheroids in the pontocerebellar fibers; and (3) marked degeneration of the posterior columns and spinocerebellar tracts. Electron microscopic examination revealed that abnormal mitochondria were markedly aggregated in smooth muscle cells and endothelium of the cerebral and cerebellar blood vessels. These fine structural findings suggest a "mitochondrial angiopathy". PMID:1575024

  9. [Electron microscopic histochemical study in human trabecular meshwork--Second report: location of glycoconjugate residues using lectins].

    PubMed

    Nagata, S

    1994-01-01

    The location of fourteen lectins in normal human trabecular meshworks were investigated with the electron microscope. The specimens were embedded in Lowicryl K4M at low temperature. Ultrathin sections were stained with biotin labeled lectins and colloidal gold labeled streptoavidin and observed with the electron microscope. ABA, ConA, DSA, PHA-E1, PHA-L4, WGA, LCA, and RCA120 were localized around fine fibrils underneath the endothelium of the trabecular wall of the Schlemm's canal (type I plaque) and collagenous fibers in the corneoscleral meshworks. ABA, ConA, and DSA were localized on the long-spacing collagens, basal membrane, microfibrils of elastic fiber (type II plaque), and fine granular (type III plaque). The present study indicated that extracellular matrices of normal human trabecular meshworks contained specific glycoconjugate residues. PMID:8109442

  10. Molecular electronics under the microscope

    NASA Astrophysics Data System (ADS)

    2015-03-01

    The field of molecular electronics has developed significantly as experimental techniques to study charge transport through single molecules have become more reliable. Three Articles in this issue highlight how chemists can now better understand and control electronic properties at the molecular level.

  11. 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

  12. Trim simulations and possible studies for edge-on ion irradiation of electron microscope specimens

    SciTech Connect

    Thompson, L.J.; Allen, C.W.; Frischherz, M.C. |; Otero, M.P. |

    1992-12-31

    A TRIM code has been modified to simulate a special technique, first described at the Spring 92 MRS Meeting, for in-situ transmission electron microscope (TEM) experiments involving simultaneous ion irradiation, in which the resultant phenomena are observed as in a cross-section TEM specimen without further specimen preparation. Instead of ion-irradiating the film or foil specimen normal to the major surfaces and observing in plan view (i.e., in essentially the same direction), the specimen is irradiated edge-on (i.e., parallel to the major surfaces) and is observed normal to the depth direction of the irradiation. Results of calculations utilizing the modified TRIM code are presented for cases of 200 and 500 keV Co impinging onto the edge of Si films 200 and 600 nm thick. Limitations of the technique are discussed and feasibility of experiments involving implantation of Co into Si and the formation of CoSi{sub 2}, which employ this technique, are briefly discussed. 10 refs, 3 figs.

  13. 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.

  14. 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

  15. 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.

  16. [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

  17. Polyethylene glycol-induced internalization of bacteria into fungal protoplasts: Electron microscopic study and optimization of experimental conditions

    SciTech Connect

    Guerra-Tschuschke, I.; Martin, I.; Gonzalez, M.T. )

    1991-05-01

    The authors studied the mechanism of internalization of Escherichia coli into Saccharomyces cerevisiae induced by polyethylene glycol (PEG) and optimized the experimental conditions. Transmission electron microscope studies revealed that the principal factor involved in the internalization was the degree of cell aggregation attained. Internalization occurred mainly by an endocytosis-like mechanism and took place during the elimination of PEG. The optimum conditions were to treat a mixed pellet of both microorganisms with 15% PEG and then gradually dilute the polymer. The same conditions were applied to E. coli and Aspergillus nidulans, with similar results.

  18. Scanning electron microscopic study of teeth restored with fiber posts and composite resin: An in vitro study

    PubMed Central

    Sridhara, K. S.; Mankar, Sunil; Jayshankar, C. M.; Vinaya, K.

    2014-01-01

    Aims and Objectives: The aim of this study is to compare and evaluate the thickness of resin dentin interface zones (RDIZ) obtained by luting carbon fiber post to intra-radicular dentin, either with All-Bond 2 bonding agent and C and B composite cement or Panavia F dentin-bonding system and Panavia F resin cement. Materials and Methods: Twenty single rooted mandibular premolars of similar sizes were prepared for the carbon fiber post after biomechanical preparation and obturation. They were divided into two groups, Group 1 and 2 of 10 samples each. Carbon fiber posts used for Group 1 samples were luted using All-Bond 2 and C and B cement. For Group 2 carbon fiber posts were luted using Panavia F dentin-bonding system and Panavia F resin cement. All the 20 samples were sectioned longitudinally and marked at three points on the length of the tooth from the dentin-core interface to the apex at 2 mm, 5 mm, and 8 mm to get coronal, middle, and apical areas, respectively. The formation and thickness (width) of the RDIZ at the marked areas was evaluated by scanning electron microscope using ×1000 magnification. The results were statistical analyzed. Results: Irrespective of the adhesive systems used all specimens showed a RDIZ formation. Microscopic examination of Group 1 showed significantly higher percentage of RDIZ (P < 0.05) than Group 2. RDIZ morphology was easily detectable at coronal and middle areas of all specimens. Conclusion: All-Bond 2 showed denser and wider RDIZ compared with the Panavia F. PMID:25210390

  19. 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.

  20. Transmission Electron Microscope Studies of Martian 'Iddingsite' in the Nakhlite Meteorite MIL 090032

    NASA Astrophysics Data System (ADS)

    Hallis, L.; Ishii, H.; Bradley, J. P.; Taylor, J.

    2012-12-01

    As with the other nakhlites, MIL 090032 contains iddingsite-like alteration veins in the olivine phenocrysts that reportedly originated on Mars[1]. These 'iddingsite' veins have been analysed in a number of the nakhlite meteorites[2], and the presence of hydrous silicate gel, smectite clays, siderite, Fe-oxides, gypsum and carbonate have been reported. The presence and proportion of these phases in the different nakhlites appears to relate to the composition and concentration of the martian brine that flowed through each, thus supporting the theory that the nakhlite secondary alteration phases were produced by an evaporation sequence on the surface of Mars[3]. We analyzed these martian 'iddingsite' veins in MIL 090032 with the aim of placing it and its three paired meteorites within the nakhlite alteration sequence. By expanding our knowledge of this alteration sequence, we will gain extra insight into the conditions on the martian surface at the time these 'iddingsite' veins formed (<1.3 Ga). We utilized the 80-300 kV aberration-corrected FEI Titan (Scanning) Transmission Electron Microscope (S-TEM) system at Lawrence Livermore National Laboratory to analyse a ~15×8μm Focused Ion Beam (FIB) section of an 'iddingsite' vein in MIL 090032. To allow the electrons to be transmitted through the FIB section, it was milled down to ~150 nm thickness. Our initial TEM data indicate this FIB section contains hydrous amorphous silicate gel towards the center, with areas of phyllosilicate (possibly nontronite) interspersed within this central zone. Towards the outer edge of the vein jarosite and then gypsum sulfates were present. At the very edge only partially broken down olivine was observed. The presence of phyllosilicate and silicate gel in this vein suggests the 'iddingsite' in MIL 090032 was produced by water-rich brine, and the abundance of sulfates suggests the brine was enriched in sulfur. This assemblage of minerals is most in line with that of the 'iddingsite

  1. Effect of Piper sarmentosum Extract on the Cardiovascular System of Diabetic Sprague-Dawley Rats: Electron Microscopic Study

    PubMed Central

    Thent, Zar Chi; Seong Lin, Teoh; Das, Srijit; Zakaria, Zaiton

    2012-01-01

    Although Piper sarmentosum (PS) is known to possess the antidiabetic properties, its efficacy towards diabetic cardiovascular tissues is still obscured. The present study aimed to observe the electron microscopic changes on the cardiac tissue and proximal aorta of experimental rats treated with PS extract. Thirty-two male Sprague-Dawley rats were divided into four groups: untreated control group (C), PS-treated control group (CTx), untreated diabetic group (D), and PS-treated diabetic group (DTx). Intramuscular injection of streptozotocin (STZ, 50 mg/kg body weight) was given to induce diabetes. Following 28 days of diabetes induction, PS extract (0.125 g/kg body weight) was administered orally for 28 days. Body weight, fasting blood glucose, and urine glucose levels were measured at 4-week interval. At the end of the study, cardiac tissues and the aorta were viewed under transmission electron microscope (TEM). DTx group showed increase in body weight and decrease in fasting blood glucose and urine glucose level compared to the D group. Under TEM study, DTx group showed lesser ultrastructural degenerative changes in the cardiac tissues and the proximal aorta compared to the D group. The results indicate that PS restores ultrastructural integrity in the diabetic cardiovascular tissues. PMID:23304208

  2. Combined infrared and analytical electron microscope studies of interplanetary dust particles

    NASA Astrophysics Data System (ADS)

    Bradley, J. P.; Humecki, H. J.; Germani, M. S.

    1992-08-01

    Ultramicrotomed thin sections (less than 100 nm thick) of eight chondritic interplanetary dust particles (IDPs) were studied by analytical electron microscopy and IR microspectroscopy with the objective of identifying IDPs or their specific components with IR spectral transmission characteristics at 10 microns similar to those of comets. Two IDPs are identified whose silicate emission characteristics between 8 and 12 microns are similar to those of comets Halley and Bradfield. Implanted solar flare tracks and sputtered rims resulting from solar wind damage suggest that the minerology and petrography of these IDPs have not been significantly perturbed since ejection from their parent bodies.

  3. 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.

  4. Scanning electron microscope study of ancient parasite eggs recovered from Korean mummies of the Joseon Dynasty.

    PubMed

    Shin, Dong Hoon; Lim, Do-Seon; Choi, Ki-Ju; Oh, Chang Seok; Kim, Myeung Ju; Lee, In Sun; Kim, Seok Bae; Shin, Jeong Eun; Bok, Gi Dae; Chai, Jong Yil; Seo, Min

    2009-02-01

    We have previously shown that parasite eggs have been identified in the coprolites of Korean mummies. These eggs have shed light on parasitic infection patterns in Korean populations living several hundred years ago. We conducted a scanning electron microscopy (SEM) study on ancient Trichuris trichiura, Ascaris lumbricoides, Metagonimus yokogawai, Paragonimus westermani, and Gymnophalloides seoi eggs recovered from Korean mummies of the Joseon Dynasty. We anticipated that the taphonomic conditions of mummification would alter the eggs of certain species but not of others. Our SEM data show that each species of ancient egg exhibited different degrees of preservation. Thus, some of them, for example, M. yokogawai, exhibited a better preservation status than others, suggesting that they should be the first candidates considered when choosing subjects for future paleoparasitological studies. PMID:18601576

  5. 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.

  6. 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

  7. [Light- and electron-microscopical study of Pelomyxa flava sp. n. (archamoebae, pelobiontida)].

    PubMed

    Frolov, A O; Chistiakova, L V; Malysheva, M N

    2010-01-01

    Using light and electron microscopy, the morphology of a new species of pelobionts Pelomyxa flava was studied. The coverings of P. flava are represented by plasma membrane bearing the thick layer of weakly structured glycocalyx on its outer surface. Numerous flagella are often located on the tops of short conical pseudopodia. Kinetosomes of flagella reach a length of 0.9 microm and are hollow with a pronounced central filament. Rootlet system is represented by three groups of microtubules: the radial, basal and microtubules of lateral root. The transition zone is short and does not exceed the level of cell surface; the axoneme is characterized by an unstable set of microtubules. Trophic stages of P. flava life cycle are presented by binuclear cells; plasmotomy is performed at the tetranuclear stage. Nuclei have a granular structure. Fibrillar nuclear bodies were revealed in karyoplasm. The nuclei shell has a complex organization. On its surface, the outer membrane has a layer of electron-dense material which contacts with short microtubules, located in a row at the surface of the nuclear envelope. The bubbles and cisterns of endoplasmic reticulum, which are the derivatives of the nuclear envelope, are located outward from the microtubules. The presence of structural and digestive vacuoles and grains of glycogen was noticed in P. flava endoplasm. Three types of prokaryotic cytobionts were revealed. Large multi-membranous organelles reaching 5 pm in diameter were described for the first time. We discuss morphology and biology features of P. flava in comparison with the previously studied Pelomyxa species. PMID:21105367

  8. Atomic sputtering in the analytical electron microscope

    SciTech Connect

    Bradley, C.R.; Zaluzec, N.J.

    1988-08-01

    The advent of UHV medium voltage electron microscopes has brought the microanalyst to a regime of operating conditions in which electron beam induced damage can now be introduced to metallic specimens of medium to high atomic number. We report upon calculations of electron beam induced atomic sputtering which will have bearing upon the next generation of medium voltage analytical electron microscopes. The cross-section calculations reported herein have been completed for all solid elements of the periodic table for incident electron energies up to 1.5 MeV. All computer codes needed to duplicate these computations are available through the EMMPDL. 12 refs., 2 figs., 1 tab.

  9. [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

  10. Degranulation patterns of eosinophils in advanced gastric carcinoma: an electron microscopic study.

    PubMed

    Caruso, R A; Ieni, A; Fedele, F; Zuccalà, V; Riccardo, M; Parisi, E; Parisi, A

    2005-01-01

    Recruitment and activation of eosinophils have been studied intensely in asthma and other allergic diseases. Less is known about the infiltration and degranulation patterns of eosinophils in the tumor stroma. Seven cases of advanced gastric carcinomas were found to be massively infiltrated by eosinophils and studied by light and electron microscopy. Gastric carcinomas, despite having similar numbers of tissue eosinophils, exhibited markedly different degranulation patterns. In 2 cases, resting nondegranulating eosinophils were found. Piecemeal degranulation was the predominant mode of secretion from eosinophils localized within the tumor stroma in 4 cases. Eosinophil exocytosis and cytolysis were rarely observed. In 1 case, crystals morphologically similar to Charcot-Leyden crystals were observed at the extracellular level as well as in phagosomes of tissue macrophages, confirming active sequestrations of eosinophil Charcot-Leyden protein by macrophages in vivo. In the same case, eosinophils showed characteristic features of early and late apoptotic changes, such as condensed chromatin, focal dilatation of nuclear envelope, and preserved plasma membrane. Morphological association between apoptotic eosinophils and deposition of granules in the tumor stroma was found. Extracellular deposition of intact granules from apoptotic eosinophils was distinct from eosinophilic (necrotic) cytolysis, and has reported previously in experimental studies in vitro. To the knowledge of the authors, this case represents the first report of late apoptotic eosinophils that release their granules within the tumor stroma in a human gastric carcinoma. PMID:15931778

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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

  16. A histological and electron-microscopic study of the architecture and ultrastructure of human periodontal tissues.

    PubMed

    Raspanti, M; Cesari, C; De Pasquale, V; Ottani, V; Strocchi, R; Zucchelli, G; Ruggeri, A

    2000-03-01

    The structure of periodontal tissues is still far less understood than their clinical relevance would demand. Here the periodontal ligament and radicular cementum in healthy human teeth were studied by light microscopy, transmission and scanning electron microscopy. These observations showed that the extracellular matrix of periodontal ligament is composed of a loose plexus of wavy collagen fibrils immersed in a highly hydrated interfibrillar matrix. Only close to their cemental insertion do these fibrils gather in thick, parallel fascicles (Sharpey's fibres). As these cross the mineralization front, they become infiltrated by the mineral phase and continue directly with the cementum matrix. Sharpey's fibres, "extrinsic" and "intrinsic" fibres all appear to be the same fibres, which bend and branch repeatedly during their course within the thickness of the cementum. Because of its physical continuity with the cementum, a limited portion of the periodontal ligament approximately corresponding to the length of Sharpey's fibres remains unaffected by enzymatic digestion of the interfibrillar matrix while the rest of the ligament is completely dissolved. The findings here indicate that the periodontal ligament and dental cementum join by a continuity rather than a contiguity of structures; that the collagen-mineral relation in cementum has distinctive features in comparison to other hard tissues; that extrinsic and intrinsic fibres of cementum and the adjoining portion of periodontal ligament form a structural, mechanical and metabolic unit distinct from the central, more metabolically active portion of the periodontal ligament. PMID:10761871

  17. 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.

  18. 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

  19. Microvascular architecture of the rabbit eye: a scanning electron microscopic study of vascular corrosion casts.

    PubMed

    Ninomiya, Hiroyoshi; Inomata, Tomo; Kanemaki, Nobuyuki

    2008-09-01

    The microvasculature of the eyes of 5 rabbits was investigated using scanning electron microscopy on corrosion casts. The study revealed that the pars plana vessels draining blood from the iris and ciliary body coursed directly into the anterior vortex venous system constituting the scleral venous plexus (the venous circle of Hovius). The episcleral vasculature was found to possess a specialized morphology, with channels draining the aqueous humor. The capillaries of the third palpebral, bulbar and palpebral conjunctiva formed a single-layered capillary network approximately parallel to the epithelium and formed a well-developed venous plexus in the stroma. The retina was found to be merangiotic, meaning that vessels were present only in a small part of the retina, extending in a horizontal direction to form bands on either side of the optic disc. Channels representing the aqueous veins that drained blood mixed with aqueous humor were found to derive directly from the suprachoroidal space and communicate with the scleral venous plexus via the anterior vortex veins. The functional significance of the microvasculature of the iris, cilia, retina and choroid is discussed in this report as well. The elaborate microvasculature of the conjunctiva may be a prerequisite for the exchange of nutrients and gasses between the cornea and the vessels across the conjunctival epithelium when the eyelids are shut during sleep, and possibly for the dynamics of eye drop delivery. The scleral venous plexus in rabbits may be analogous to the scleral venous sinus (Schlemm's canal) in rats, primates and humans. PMID:18840961

  20. Light and electron microscopic study of stress-shielding effects on rat patellar tendon.

    PubMed

    Muellner, T; Kwasny, O; Loehnert, V; Mallinger, R; Unfried, G; Schabus, R; Plenk, H

    2001-11-01

    In this second part of our study, the histomorphologic changes occurring in the patellar tendon (PT) of rats after sole stress-shielding were evaluated. In seven adult albino rats, both PTs were exposed by straight skin incision and then stress-shielded on one side by a cerclage, while the contralateral PT served as the sham-operated control. One animal died after the operation and was used as a negative control. After 10 weeks of otherwise unrestricted motion, the rats were killed, and the histomorphology of all PT specimen pairs compared by light and transmission electron microscopy. Light microscopy showed mid-portion thickening and irregularity of collagen bundles in the stress-shielded tendons. Intense remodelling was demonstrated by increased cellularity and vascularity, as well as by enrichment in acidic proteoglycans. Ultrastructural evaluation and morphometry revealed a predominance of large diameter (peak between 180 and 260 nm) collagen fibrils in the sham-operated controls, while in the stress-shielded tendons the number of apparently new, small-diameter (peak between 40 and 60 nm) collagen fibrils increased (up to 77% per cross-sectional field of view). The difference in peak diameters was statistically significant (p < 0.0005). This rat model demonstrated that sole stress-shielding not only causes biomechanical alterations, but also intense tissue remodelling and significant morphological changes in the collagen fibrils in the patellar tendon, comparable to so-called 'ligamentization' in experimental and clinical patellar tendon grafts for anterior cruciate ligament reconstruction. PMID:11768636

  1. Scanning electron and light microscopic study of microbial succession on bethlehem st. Nectaire cheese.

    PubMed

    Marcellino, S N; Benson, D R

    1992-11-01

    St. Nectaire cheese is a semisoft cheese of French origin that, along with Brie and Camembert cheeses, belongs to the class of surface mold-ripened cheese. The surface microorganisms that develop on the cheese rind during ripening impart a distinctive aroma and flavor to this class of cheese. We have documented the sequential appearance of microorganisms on the cheese rind and in the curd over a 60-day ripening period. Scanning electron microscopy was used to visualize the development of surface fungi and bacteria. Light microscopy of stained paraffin sections was used to study cross sections through the rind. We also monitored the development of bacterial and yeast populations in and the pH of the curd and rind. The earliest stage of ripening (0 to 2 days) is dominated by the lactic acid bacterium Streptococcus cremoris and multilateral budding yeasts, primarily Debaryomyces and Torulopsis species. Geotrichum candidum follows closely, and then zygomycetes of the genus Mucor develop at day 4 of ripening. At day 20, the deuteromycete Trichothecium roseum appears. From day 20 until the end of the ripening process, coryneforms of the genera Brevibacterium and Arthrobacter can be seen near the surface of the cheese rind among fungal hyphae and yeast cells. PMID:16348797

  2. Seasonal variations in the heterologous binding of viscacha spermatozoa. A scanning electron microscope study.

    PubMed

    Merlo, Claudia Aguilera; Muñoz, Estela; Dominguez, Susana; Fóscolo, Mabel; Scardapane, Luis; de Rosas, Juan Carlos

    2005-12-01

    Seasonal changes in the reproductive activity of the adult male viscacha (Lagostomus maximus maximus) were investigated during the annual reproductive cycle. Assays of heterologous in vitro binding between compatible gametes were used to evaluate the ability of viscacha spermatozoa to achieve primary binding during its annual reproductive cycle. Sperm were collected by mincing cauda epididymis in HECM-3 medium and the sperm concentration and motility were evaluated. Cumulus-free and zona-free oocytes obtained from superovulated hamsters were inseminated in vitro with capacitated sperm suspensions, incubated at 37 degrees C, 5% CO2 for 3 h, and then processed for studies by scanning electronic microscopy. Statistical analysis was used to compare the quantitative differences. The number of spermatozoa significantly decreases during the regression period, while sperm motility was progressive speed in both periods. During the active period elevated sperm binding to cumulus-free and zona-free oocytes was observed, while the binding during the regression period decreased drastically. In both periods, oocyte microvilli covered sperm heads and tails. These results suggest that the ability of viscacha spermatozoa to participate in gamete recognition is profoundly affected. This would likely be related to different functional stages of the spermatozoa and their epididymal microenvironment during the annual reproductive cycle of viscacha. PMID:16524245

  3. 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

  4. 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.

  5. The Effect of Preparation Size on Efficacy of Smear Layer Removal; A Scanning Electron Microscopic Study

    PubMed Central

    Tabrizizadeh, Mehdi; Shareghi, Ameneh

    2015-01-01

    Introduction: Enlargement of the root canal may potentially affect efficient smear layer (SL) removal. The aim of the present in vitro study was to compare SL removal following canal preparation with two different sizes/tapers by means of scanning electron microscopy (SEM). Methods and Materials: A total of 50 extracted human mandibular premolars were decoronated. The teeth were randomly divided into two experimental groups (n=20) and two negative control groups. In groups 1 and 2 the sizes of master apical file (MAF) were #25 and 40, respectively. Coronal part of the canals were flared with #2 Piezo drills in group 1 and sizes #2 to 6 in group 2. Finally FlexMaster NiTi rotary instruments were used to complete canal preparation (25/0.04 and 35/0.06 in groups 1 and 2, respectively). The irrigation protocol consisted of 10 mL of 17% ethylenediaminetetraacetic acid (EDTA) for 1 min followed by 10 mL of 5.25% NaOCl for 3 min. The patency of dentinal tubules was evaluated under SEM with Hülsmann scores. Data were analyzed with the Kruskal-Wallis and Mann-Whitney U tests. Results: The number of patent dentinal tubules in coronal third of the group 1 was significantly more than group 2 (P<0.001). However, this difference was not significant for the middle and apical segments. There was a significant difference in the number of patent dentinal tubules between coronal, middle and apical thirds (P<0.05). Conclusion: Increasing the canal preparation size did not lead to better cleanliness of the canal walls and more efficient smear layer removal. PMID:26213539

  6. Minimal Apical Enlargement for Penetration of Irrigants to the Apical Third of Root Canal System: A Scanning Electron Microscope Study

    PubMed Central

    Srikanth, P; Krishna, Amaravadi Gopi; Srinivas, Siva; Reddy, E Sujayeendranatha; Battu, Someshwar; Aravelli, Swathi

    2015-01-01

    Background: The aim of this study was to determine minimal apical enlargement for irrigant penetration into apical third of root canal system using scanning electron microscope (SEM). Materials and Methods: Distobuccal canals of 40 freshly extracted human maxillary first molar teeth were instrumented using crown-down technique. The teeth were divided into four test groups according to size of their master apical file (MAF) (#20, #25, #30, #35 0.06% taper), and two control groups. After final irrigation, removal of debris and smear layer from the apical third of root canals was determined under a SEM. Data was analyzed using Kruskal–Wallis and Mann–Whitney tests. Results: Smear layer removal in apical third for MAF size #30 was comparable with that of the control group (size #40). Conclusion: Minimal apical enlargement for penetration of irrigants to the apical third of root canal system is #30 size. PMID:26124608

  7. Cryo-scanning electron microscopic study on freezing behavior of xylem ray parenchyma cells in hardwood species

    PubMed

    Fujikawa; Kuroda

    2000-12-01

    Differential thermal analysis (DTA) has indicated that xylem ray parenchyma cells (XRPCs) of hardwood species adapt to freezing of apoplastic water either by deep supercooling or by extracellular freezing, depending upon the species. DTA studies indicated that moderately cold hardy hardwood species exhibiting deep supercooling in the XRPCs were limited in latitudinal distribution within the -40 degrees C isotherm, while very hardy hardwood species exhibiting extracellular freezing could distribute in colder areas beyond the -40 degrees C isotherm. Predictions based on the results of DTA, however, indicate that XRPCs exhibiting extracellular freezing may appear not only in very hardy woody species native to cold areas beyond the -40 degrees C isotherm but also in less hardy hardwood species native to tropical and subtropical zones as well as in a small number of moderately hardy hardwood species native to warm temperate zones. Cryo-scanning electron microscopic (cryo-SEM) studies on the freezing behavior of XRPCs have revealed some errors in DTA. These errors are originated mainly due to the overlap between exotherms produced by freezing of water in apoplastic spaces (high temperature exotherms, HTEs) and exotherms produced by freezing of intracellular water of XRPCs by breakdown of deep supercooling (low temperature exotherms, LTEs), as well as to the shortage of LTEs produced by intracellular freezing of XRPCs. In addition, DTA results are significantly affected by cooling rates employed. Further, cryo-SEM observations, which revealed the true freezing behavior of XRPCs, changed the previous knowledge of freezing behavior of XRPCs that had been obtained by freeze-substitution and transmission electron microscopic studies. Cryo-SEM results, in association with results obtained from DTA that were reconfirmed or changed by observation using a cryo-SEM, revealed a clear tendency of the freezing behavior of XRPCs in hardwood species to change with changes in the

  8. Electron microscopic study of a glass-forming water/oil pseudo-three-component microemulsion system

    SciTech Connect

    Green, J.L. )

    1990-07-26

    The development of microemulsion systems that do not break down during cooling and in which neither dispersed nor matrix phases crystallize during the cooling process opens the way to direct studies of the microemulsion structure and also the investigation of the dispersed liquid in unusual states. The authors report the first water-in-oil example of this type of system. It was obtained by partial replacement of water by glycerol and total replacement of normal paraffin by ethylcyclohexane, in the water/oil/didodecyldimethylammonium bromide three-component system. The phase diagram at 25{degree}C indicates a remarkably wide range of clear-phase compositions. A dispersed droplet structure for the water-rich range is unequivocally established by direct electron microscope imaging of the vitrified microemulsion, using the freeze-fracture technique.

  9. The fate of (125I)iodoepidermal growth factor in isolated hepatocytes: a quantitative electron microscopic autoradiographic study

    SciTech Connect

    Carpentier, J.L.; Gorden, P.; Freychet, P.; Canivet, B.; Orci, L.

    1981-09-01

    When (125I)iodoepidermal growth factor is incubated with freshly isolated rat hepatocytes, cell-associated radioactivity reaches apparent steady state by 60 min at 20 C and by 30 min of incubation at 37 C. When the distribution of cell-associated radioactivity is studied at different times of incubation by quantitative electron microscopic autoradiography, the ligand initially associates with the plasma membrane and is progressively internalized as a function of time. The internalized ligand preferentially associates with lysosome-like structures. Qualitatively, these events are similar to those previously obtained with labeled insulin and glucagon in this cell, but quantitatively, the internalization of epidermal growth factor is much greater. The data suggest that the ligand or its specific receptor rather than the cell type is the major determinant of the rate of internalization.

  10. A rare case of a multicentric peripheral ameloblastoma of the gingiva. A light and electron microscopic study.

    PubMed

    Hernandez, G; Sanchez, G; Caballero, T; Moskow, B S

    1992-04-01

    A rare case of a multicentric peripheral ameloblastoma of the gingiva in a 54-year-old male patient is described along with a light and electron microscopic study of the excised tumors. The peripheral ameloblastoma is considered to be the gingival counterpart of the more common intraosseous ameloblastoma. Although both tumors have similar histomorphologic characteristics, their clinical appearance and behavior are completely different. The peripheral ameloblastoma is slow growing and non-invasive, and recurrence is uncommon following excision. The more common central ameloblastoma, is locally invasive and can destroy large segments of the jaw. The histogenesis of the peripheral ameloblastoma and several other odontogenic tumors of the gingiva serves to illustrate the proliferative potential of the basal cell layer of gingival epithelium. PMID:1569230

  11. Study of the surface structure of butterfly wings using the scanning electron microscopic moiré method

    NASA Astrophysics Data System (ADS)

    Kishimoto, Satoshi; Wang, Qinghua; Xie, Huimin; Zhao, Yapu

    2007-10-01

    Scanning electron microscopic (SEM) moiré method was used to study the surface structure of three kinds of butterfly wings: Papilio maackii Menetries, Euploea midamus (Linnaeus), and Stichophthalma howqua (Westwood). Gratings composed of curves with different orientations were found on scales. The planar characteristics of gratings and some other planar features of the surface structure of these wings were revealed, respectively, in terms of virtual strain. Experimental results demonstrate that SEM moiré method is a simple, nonlocal, economical, effective technique for determining which grating exists on one whole scale, measuring the dimension and the whole planar structural character of the grating on each scale, as well as characterizing the relationship between gratings on different scales of each butterfly wing. Thus, the SEM moiré method is a useful tool to assist with characterizing the structure of butterfly wings and explaining their excellent properties.

  12. Effects of Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae) larvae on the degranulation of dermal mast cells in mice; an electron microscopic study.

    PubMed

    Kalender, Yusuf; Kalender, Suna; Uzunhisarcikli, Meltem; Ogutcu, Ayşe; Açikgoz, Fatma

    2004-01-01

    The pine caterpillar Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae) is found in pine woods. Hairs of the T. pityocampa caterpillar cause a cutaneous reaction in humans and animals. Mast cells are responsible for allergic reactions in mammals. In this study male swiss albino mice were divided into two groups: 5 mice in the control group and 25 mice in the experimental group. The dorsal skin of mice was shaved. The mice in the experimental group and T. pityocampa larvae (fifth instar, approximately n=100) were put in the same cage. Dermal mast cells of mice exposed to T. pityocampa were examined with a transmission electron microscope and compared to the control group 1, 3, 6, 12 and 24 hours after exposure. Dermal mast cell degranulation in mice was observed 12 and 24 hours after exposure. PMID:15521642

  13. 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. PMID:1108638

  14. Dissolution and scanning electron microscopic studies of Ca,P particle-containing bioactive glasses.

    PubMed

    Kangasniemi, I M; Vedel, E; de Blick-Hogerworst, J; Yli-Urpo, A U; de Groot, K

    1993-10-01

    Calcium phosphate (Ca,P) precipitation behavior on the surface of two bioactive glasses and four bioactive glass composites--two with hydroxylapatite (Ca10(PO4)6 (OH)2) and two with rhenanite (CaNaPO4)--were studied in simulated body fluid (SBF) and in Tris-Buffer at 5, 8, 16, 24, 48, 72, and 144 h. The weight loss of the materials was measured and the amount of precipitation was estimated using scanning electron microscopy with electrochemical detection (SEM-EDX) analysis. The test was repeated for one glass and its respective rhenanite composite every 3 h until 60 h and thereafter every 10 h until 150 h in SBF. Atomic absorption spectroscopy, spectrophotometry, SEM-EDX analysis, and pH measurements were performed on these samples. It is shown that in vitro the composite materials have a higher capacity for Ca,P precipitation than the glasses. Weight losses of the materials correlate well with their composition. Both the glass and Ca,P phases influence the precipitation mechanism and rate. Precipitation begins preferably from the glass phase. Ca,P particles clearly influence the time of onset and rate of precipitation. Cross-sectional EDX analysis of the samples revealed an absence of a clear Si-rich layer in glass A0B0 (SiO2 53.9 mol %, Na2O 27.5, CaO 12.4, P2O5 6.2, Al2O3 0.0 and B2O3 0.0) composites. This was attributed to the presence of extra calcium and phosphate ions on the surface of the material. The ion-concentration and pH change curves offered insight into the mechanism of precipitation. A connection was established between SEM-EDX results and the release curves. Formation of an Si,Ca,Na film was observed that seemed to initiate the Ca,P precipitation.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8245037

  15. Miniature electron microscopes for lithography

    NASA Astrophysics Data System (ADS)

    Feinerman, Alan D.; Crewe, David A.; Perng, Dung-Ching; Spindt, Capp A.; Schwoebel, Paul R.; Crewe, Albert V.

    1994-05-01

    Two inexpensive and extremely accurate methods for fabricating miniature 10 - 50 kV and 0.5 - 10 kV electron beam columns have been developed: `slicing,' and `stacking.' Two or three miniature columns could be used to perform a 20 nm or better alignment of an x-ray mask to a substrate. An array of miniature columns could be used for rapid wafer inspection and high throughput electron beam lithography. The column fabrication methods combine the precision of semiconductor processing and fiber optic technologies to create macroscopic structures consisting of charged particle sources, deflecting and focusing electrodes, and detectors. The overall performance of the miniature column also depends on the emission characteristics of the micromachined electron source which is currently being investigated.

  16. 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

  17. A preliminary optical and electron microscopic study of the beta(1) integrin distribution pattern of human osteosarcoma-derived cells.

    PubMed

    Banai, Kiarash; Brady, Ken; McDonald, Fraser

    2004-07-01

    Immunogold labelling was used to study the organisation of the beta(1) integrins on osteosarcoma-derived osteoblasts (Saos-2 and MG-63). Monolayers of cells were prepared in multiwell culture plates on both uncovered and collagen-covered coverslips, and beta(1) integrins were primarily labelled using mouse monoclonal antibodies to beta(1) integrins. Indirect immunofluorescence labels using an anti-mouse fluorescein-conjugated goat antibody showed an even distribution of the beta(1) integrins on the cell membranes of all cell types used. A concentration of 2 microg/ml of the primary antibodies and a 1:100 dilution of the secondary antibodies were determined as the optimal concentration for labelling to use with indirect localisation of the primary antibodies gold conjugated to goat anti-mouse antibodies and viewed under an electron microscope. Ten nanometre gold particles were used for transmission electron microscopy (TEM) and 40 nm gold particles for scanning electron microscopy. TEM showed that beta(1) integrins were mainly clustered on the cell membrane processes with less labelling on the cell membranes themselves. The distribution of beta(1) integrins on osteosarcoma cells supports the concept that integrins may function by forming focal adhesions at the site of the cytoplasmic membrane processes. PMID:15241608

  18. 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

  19. A transmission electron microscopical study of the tegument of Maritrema feliui (Digenea: Microphallidae).

    PubMed

    Świderski, Zdzisław; Montoliu, Isabel; Feliu, Carlos; Gibson, David I; Miquel, Jordi

    2013-12-01

    The tegument of the microphallid digenean Maritrema feliui, examined by means of TEM, is described as a syncytial epithelium organised into two layers. The outer layer is an external anucleate, cytoplasmic region connected to a second region composed of nucleate perikarya (cytons) deeply embedded in the surrounding cortical parenchyma. The surface layer of the tegument is covered by a plasma membrane with many deep invaginations, which are apparently pinocytotic. This layer also bears numerous large, electron-dense spines of two types, which are intracellular and attached to the basal plasma membrane. Its cytoplasm is rich in free ribosomes, contains numerous mitochondria, disc-shaped granules frequently arranged in a rouleau, and several large, moderately electron-dense, membranous bodies. The subtegumentary perikarya and their nuclei, which are both flattened, are described in detail, as are their connections with the surface tegument. These perikarya appear to be the source of the disc-shaped granules and some of the other inclusions present in the surface layer. The main characteristics of the tegumental structure of M. feliui are commented upon in relation to the findings of previous publications and their suggested functions. PMID:24338308

  20. 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

  1. 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

  2. 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

  3. Electron microscopic studies on the initial process of lysozyme crystal growth

    NASA Astrophysics Data System (ADS)

    Michinomae, M.; Mochizuki, M.; Ataka, M.

    1999-02-01

    The initial process of lysozyme crystallization has been investigated by negatively stained electron microscopy. In the initial process of crystallization, two steps were distinguished by the appearance of associating protein molecules. One is the formation of the short threads, and the other the formation of the spherical structure (looks like a rice-ball). From among the mass of the rice-balls, larger structure appears. Some of them show the arrangement of molecules as a crystalline lattice. The spacing between the molecules agrees with one of the lattice constants known for the tetragonal lysozyme crystals. The rice-balls may be taken into crystals as essential growth units. Similarly, the thread-like structures may be the unit to form the rice-balls that appear in the next step.

  4. Residual acrylic adhesive after removal of plastic orthodontic brackets: a scanning electron microscopic study.

    PubMed

    Caspersen IVAR

    1977-06-01

    After etching for one minute with 35 per cent phosphoric acid, thirty-eight permanent teeth were furnished with plastic brackets. An additional twelve teeth were used as references and were etched but were not furnished with brackets. Four teeth served as untreated controls. Eight brackets had fallen off one week later. The remaining brackets were removed with various instruments. All the teeth were extracted and examined by scanning electron microscopy (SEM). On all of the teeth originally furnished with brackets, residual acrylic was found on the tooth surface. The SEM examination was supplemented with energy-dispersive x-ray analysis (ED) which confirmed that the observed residues differed in their chemical composition from the dental substance. PMID:326059

  5. Microcirculation of human fetal posterior root ganglia: a scanning electron microscopic study of corrosion casts.

    PubMed

    Gorczyca, J; Skawina, A; Litwin, J A; Miodoński, A J

    1998-02-01

    The vasculature of lumbar posterior root ganglia was investigated in human fetuses aged 17-24 weeks; using the corrosion casting technique and scanning electron microscopy. The arterial supply consisted of one main artery and occasional arterioles entering the ganglion at its pole and running axially, while the venous drainage was located at the periphery of the ganglion, thus indicating a centrifugal pattern of blood flow. The dense capillary network of the ganglion showed the roughly parallel course of the vessels in the central zone and an irregular arrangement in the peripheral zone where capillaries formed "nests", probably surrounding individual perikaryons of ganglionic cells. The capillaries had a sinusoidal character with numerous dilatations about twice the normal capillary size, as well as occasional larger vascular spaces resulting from capillary interconnections and suggesting the intussusceptive type of angiogenesis. PMID:9488902

  6. [Scanning electron microscopic study of films of the loose connective tissue of mice exposed to DMBA].

    PubMed

    Ol'shevskaia, L V

    1979-01-01

    Under examination by scanning electron microscopy were film samples of the subcutaneous connective tissue. The surface of the films from intact mice was even and smooth, fibroblasts have a spread pattern. Following the saline injection the film was even, collagen fibres, differing in the character of surface and the size of diameter, were readily seen. The collagen fibres formed a multilayer system with a definite orientation inside the layer. After DMBA injection the film surface would get uneven and tuberous, the fibroblast body rising over the film surface, thus the orientation of fibres and all strata was disturbed. There was a spacial rearrangement of all tissue components. It is suggested that carcinogenic agents affecting the relationship between tissue components could interfere the contact inhibition of cell division and result in the development of focal cell proliferates. PMID:113934

  7. The ventricular system of the pigeon brain: a scanning electron microscope study.

    PubMed Central

    Mestres, P; Rascher, K

    1994-01-01

    The fine structural features and regional differences of the ependyma in adult pigeons have been investigated by scanning electron microscopy. Pigeons of either sex were fixed with buffered glutaraldehyde (3%) and formaldehyde (0.5%) by intravascular perfusion. The brain was dissected using section planes adequate to expose each part of the ventricular system. The specimens were then dehydrated, critical point dried and sputtered with gold. Depending upon the distribution of cilia, microvilli and single cilia, different areas were recognised in the 4 ventricles. The topographic locations of these areas were determined using the atlas of Karten & Hodos (1967). The medial surfaces of the 1st and 2nd lateral ventricles are more densely ciliated than the lateral surfaces. In the floor of the 4th ventricle the medial part is less ciliated than the lateral parts. The circumventricular organs (subseptal organ, organum vasculosum of the lamina terminalis, infundibulum, choroid plexus, subcommissural organ, area postrema) show very characteristic surfaces and are surrounded by a transitional zone with the nonspecialized ependyma. In contrast, in the paraventricular organ the transition to the nonspecialized ependyma is rather abrupt. The ependyma covering the trochlear nucleus appears densely ciliated, differing from that of the classic circumventricular organs. Finally, the existence of openings in the caudal medullary velum, which represent direct communications between the ventricles and the subarachnoid space, was demonstrated. Images Fig. 2 Fig. 3 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 PMID:8157492

  8. Histopathological changes in the eyes in systemic lupus erythematosus: an electron microscope and immunohistochemical study.

    PubMed

    Nag, T C; Wadhwa, S

    2005-04-01

    This paper reports the histopathological findings in the eyes of a 26-year-old female patient diagnosed with systemic lupus erythematosus (SLE) with peripheral neuropathy. The patient had no significant ocular problems. She died of pneumonia after two years of suffering. The eyeballs were procured at autopsy and the retina, choroid and optic nerve processed for light and electron microscopy, and immunohistochemistry for immunoglobulin G (IgG), glial fibrillary acidic protein (GFAP), calbindin and parvalbumin. Histologically, there was haemorrhaging in the retinal nerve fibre layer. Ultrastructurally, the axons of this layer were swollen, and contained an unusual accumulation of microtubules and smooth endoplasmic reticulum. There were degenerative changes in the pericytes and smooth muscle cells of blood vessels. The capillary lumen was partially obliterated, and contained IgG, which was also detected throughout the choroid and wall of choroidal arterioles. The latter and Bruch's membrane showed fibrin deposits. The optic nerve showed infiltrated mononuclear cells near the degenerated axons, these axons lacked immunoreactivity to calbindin and parvalbumin. Compared to the control, the connective tissue sheaths of the central retinal vessels possessed a vast number of proliferated fibroblast cells, and trichrome staining showed transmural vessel scarring. Dense GFAP immunoreactivity was observed surrounding the vessel wall. These pathological changes are due to impaired blood circulation caused by haemorrhaging and vasculitis, and vessel occlusion by fibrin. The nature of the changes observed tends to indicate that a regular, thorough ophthalmic examination should be conducted even in the absence of significant ocular symptoms in SLE. PMID:15736040

  9. Effects of chondroitin sulfate on trabecular meshwork in rabbit eyes: an electron microscopic study.

    PubMed

    Fei, P F; Yue, B Y; Tso, M O

    1984-11-01

    The intraocular pressure of four New Zealand albino rabbit eyes was elevated when we replaced the aqueous humor of these eyes repeatedly with a chondroitin sulfate solution. Seen by electron microscopy, the trabecular meshwork of these eyes showed moderately increased collagen fibers, elastic fibers, and fine fibrils, and thickening of basement membrane. The amount of extracellular material present was markedly increased when compared with control eyes. Three types of basement membranes were noted. Compact multilaminated basement membrane and placoid accumulations of filamentous material with a granular background were found adjacent to the endothelial cells of the trabecular meshwork, and fine fibrils were observed around the angular aqueous veins. The ultrastructural alterations we observed were similar to those seen in some human glaucoma cases. The metabolism of trabecular meshwork cells may be affected by the long-term chondroitin sulfate treatment. As a result, extracellular matrix material appears to be accumulated in the trabecular meshwork, which may then contribute to an increased outflow resistance and a mild intraocular pressure elevation. PMID:6440803

  10. Photoacoustic and electron microscopic studies of reminerlized artificially carious enamel and dentin

    NASA Astrophysics Data System (ADS)

    El-Brolossy, T. A.; Abdalla, S.; Hassanein, O. E.; Negm, S.; Talaat, H.

    2005-06-01

    Photoacoustic (PA) spectroscopy and scanning electron microscopy (SEM) have been employed to investigate remineralized artificially carious enamel as well as dentin. The remeniralization process was carried out by applying bioactive glass particles and mineralizing solutions either directly or after the specimen was first treated with Zeolite powder. The PA was carried out to evaluate the change in the thermal parameters (diffusivity, effusivity and conductivity) quantitatively. The remineralization process was evaluated by comparing the thermal parameters to those of the healthy tissue. PA measurements show that; the values of thermal conductivity of the normal tissues (enamel: 0.9 W m-1 K-1 and dentin: 0.58 W m-1 K-1) were altered by caries to be (enamel: ≈ 0.72 W m-1 K-1 and dentin: ≈ 0.44 W m-1 K-1) and they approach their normal values after the application of the different mineralizing agents. Also the results indicate that; Bioactive glass enhances the thermal parameters of artificially carious enamel and dentin (considering the healthy values as a reference), slightly more than the mineralizing solution. Furthermore, PA measurements show that the application of Zeolite powder enhances the effect of the mineralizing agent. In order to augment the PA results, SEM was used to depict surface topography, for each treated tissue.

  11. [Inclusion Body Disease (IBD of Boids)--a haematological, histological and electron microscopical study].

    PubMed

    Keilwerth, Melanie; Bühler, Ilina; Hoffmann, Rudolf; Soliman, Hatem; El-Matbouli, Mansour

    2012-01-01

    Our objective was to evaluate diagnostic tools for the detection of Inclusion Body Disease (IBD) in bold snakes. The aetiology of IBD is unknown, and the disease has non-specific clinical signs, hence there is a need for a clinically-applicable, specific diagnostic method. We examined blood smears and liver biopsies from 26 bold snakes (17 boas and nine pythons; some of which were suspected of having IBD) for the presence of characteristic inclusion bodies. We used haematology, histology and electron microscopy to characterise samples as IBD-positive or -negative. Our results indicate that examination of a simple blood smear is sufficient to diagnose IBD in boas. Inclusion bodies in lymphocytes, erythrocytes and thrombocytes were observed. In both, boas and pythons, we detected inclusion bodies within hepatocytes. We demonstrated also that IBD was more common in boas than in pythons: only samples from two Ball Pythons (Python regius) tested positive, whereas no other Pythonidae were positive. We consider that blood smears represents a rapid, non-invasive technique for detection of IBD. PMID:23045804

  12. Application of alcian blue in the electron microscopic study of mouse and human cerebral cortex nerve cells.

    PubMed

    Castejón, H V; Castejón, O J; Viloria, M E

    1976-01-01

    Alcian blue is a cationic dye which has been used in the histochemical field for the demonstration of polyanions especially carboxylated and sulphated. The results obtained in neurons when this dye was applied to human and mouse cerebral cortex and studied with the electron microscope are the object of the present report. The CNS of normal adult mice was fixed by vascular perfusion with 2% glutaraldehyde-0.1 M sodium cacodylate-0.1 M sucrose at pH = 6.8 followed by the same fixative with the addition of 0.5% alcian blue. After perfusion, brain cortex was taken out, sectioned into small blocks and immersed in a fresh similar mixture and subsequently in OSO4. Blocks were dehydrated and embedded in araldite. Ultrathin sections were doubly stained with uranyl and lead salts. Human brain cortex taken from patients with cerebral edema was fixed by immersion with 6.5% glutaraldehyde-0.1 M sodium phosphate, pH = 7.4 followed by embedding in warm agar and sectioning in slices of 30 mum thickness which were impregnated by immersion in a mixture of 1% alcian blue-acetate buffer-3% glutaraldehyde at pH = 3.5 for 9 to 15 h at 4 degrees C and subsequently immersed in 1% buffered OSO4-0.1 M sucrose, pH = 7.4 for 2 h at 4 degrees S. Sections were dehydrated and embedded in araldite. Ultrathin sections were doubly stained by uranyl and lead salts. We have denominated the complete procedure in both instances GABOUL technique. The submicroscopic study of both tissues, at nerve cells, revealed the presence of an electron dense homogeneous substance thoroughly dispersed at the hyaloplasmic matrix of perikarya, processes and even synaptic endings. This substance was more evident around free and attached ribosomes, GOLGI apparatus, complex vesicles, dense bodies, microtubules, subsurface cisternae and synaptic vesicles. Canaliculi of endoplasmic reticulum and even the perinuclear cistern also showed a moderate content. It is suggested that this electron dense substance, being

  13. 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.

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

    PubMed

    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. PMID:7114194

  15. The aminergic innervation of the human bronchus: a light and electron microscopic study.

    PubMed Central

    Pack, R J; Richardson, P S

    1984-01-01

    Portions of bronchial wall, free of neoplasm, were obtained from human lung resected for nearby tumour. The bronchial tissue was freeze dried, fixed in formaldehyde vapour and sections examined by fluorescence microscopy. Wispy green fibres with the appearance of amine-containing nerves were seen associated with the gland acini. Fluorescent cells were also found at this location and infrequently in the epithelium. Fluorescence was blocked by pretreatment of the sections with sodium borohydride; it faded in ultraviolet light and was enhanced by incubation of the tissue with L-dopa. All these features are characteristic of specific formaldehyde-induced fluorescence of biogenic amines. Fluorescent fibres were not identified either in the smooth muscle of the airway or associated with the epithelium, although background fluorescence may have masked them at these sites. Observations by electron microscopy of human bronchial wall showed that, close to gland acini, there were nerves containing large dense-cored vesicles suggesting that they were sympathetic. After incubation of the tissue with 5-hydroxydopamine, nerves containing labelled vesicles were seen as close as 1 micron to the gland acini, though none were seen to run between the acinar cells. It is argued that these were sympathetic nerves and were close enough to the gland acini to influence their secretions. Nerves containing vesicles labelled with 5-hydroxydopamine were also seen in close association with smooth muscle cells indicating a direct sympathetic innervation of the bronchial smooth muscle. These observations are contrary to recent suggestions that the sympathetic nervous system acts only indirectly in the lungs. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:6735911

  16. Light and scanning electron microscopic study on the blood vascular system of the donkey placenta.

    PubMed

    Saber, A; Abd-Elnaeim, M; Hembes, T; Pfarrer, C; Salim, A; Leiser, R

    2008-04-01

    The donkey placenta is diffuse and epitheliochorial with numerous microplacentomes consisting of a fetal microcotyledonary and a maternal microcaruncular part. The microplacentomal vasculature during the last third of pregnancy has been investigated by light microscopy in comparison to scanning electron microscopy of the materno-fetal contact surface and corrosion casts of blood vessels after plastic instillation from either the microcotyledonary or the microcaruncular side, and, for the first time in a perissodactyle, from both sides. Morphological data were semiquantitatively evaluated. The supplying parts of both, the microcotyledonary and the microcaruncular vascular system are strictly proximo-distally oriented, thus reaching the capillary systems or working parts in the shortest way possible. The straight course of the vasculature, particularly on the fetal side, suggests the occurrence of venulo-arteriolar back diffusion. The fetal capillary system consists of convolutes confronting the maternal septal capillary complexes in a countercurrent way. This materno-fetal blood flow interrelationship is highly efficient in terms of placental exchange, which is further supported (1) by dilations and increasing coiling of the fetal venular capillary limbs in particular and (2) by a decrease in the interhaemal distance from 12.5 to 7.2 microm between the two capillary systems. Besides the countercurrent blood flow interrelationship, some maternal branch arterioles reach the septal capillary system from the maternally oriented pole of the microplacentome or microcaruncle, respectively, resulting in the less efficient crosscurrent blood flow. Hence, in the donkey placenta fetal and maternal blood vessels meet in a mix of countercurrent and crosscurrent flow patterns. PMID:18067487

  17. 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.

  18. 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.

  19. In-situ study of interconnect failures by electromigration inside a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Wetzig, Klaus; Wendrock, Horst; Buerke, Axel; Kötter, Thomas

    1999-11-01

    The influence of microstructure on electromigration damage of Al and Cu interconnects with different width and morphology was studied. At first, grain boundaries and local grain orientations before electromigration were registered and correlated with defect places. The investigations focussed on in-situ electromigration tests inside a SEM under accelerated loading conditions, on the in-situ observation of defect formation, and on orientation measurements at the interconnect grains. The position of individual grain boundaries and the misorientation of their neighbored grains seem to be decisive factors for the interconnect failure because of different diffusivities. Whereas the failure behavior of polycrystalline interconnects is sufficiently understood, bamboo structures require further investigations.

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

    PubMed Central

    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). PMID:26981314

  1. Quantitative electron microscopic study of the intracellular localization of wheat germ agglutinin in retinal neurons

    SciTech Connect

    Rhodes, C.H.; Stieber, A.; Gonatas, N.K.

    1986-12-15

    Previous work has established that, following endocytosis, wheat germ agglutinin, like a number of other plasma membrane bound ligands, is transported to the Golgi apparatus-complex. Previous studies that provided qualitative information about the intracellular distribution of internalized wheat germ agglutinin used techniques that precluded any quantitative conclusions about the relative magnitude of the labeling of endosomes, lysosomes, and the Golgi apparatus-complex. Using quantitative ultrastructural autoradiography, this study compares the time course and relative magnitude of labeling of various intracellular compartments to the labeling in the Golgi area. Fifteen minutes after intraocular injection, wheat germ agglutinin is confined to the inner surface of the retina and the immediate subsurface neuropil with little labeling of the retinal ganglion cell perikarya. Thirty minutes after injection, the plasma membrane (6.97 +/- 1.17), endosomes (10.27 +/- 3.98), smooth vesicles and tubules (1.94 +/- 1.66), and lysosomes (2.42 +/- 1.21) of the retinal ganglion cells are labeled, while the Golgi apparatus-complex is not labeled (0.29 +/- 0.25). The relative labeling density of the plasma membrane and endosomes decreases somewhat during the next 90 minutes (plasma membrane, 4.76 +/- 0.67; endosomes, 7.23 +/- 2.02), while the labeling density of smooth vesicles and tubules and of lysosomes rises (smooth vesicles and tubules, 5.56 +/- 0.94; lysosomes, 7.76 +/- 1.56). The Golgi apparatus-complex, which is unlabeled at 30 minutes, is weakly labeled at 2 hours (1.26 +/- 0.28).

  2. 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.

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

    PubMed Central

    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. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 PMID:7055211

  4. Electron Microscopic Study on the Suction Cast In Situ Ti-Fe-Sn Ultrafine Composites

    NASA Astrophysics Data System (ADS)

    Samal, Sumanta; Mondal, Barnali; Biswas, Krishanu; Govind

    2013-01-01

    The current investigation reports detailed study on the microstructural evolution in the suction cast hypereutectic Ti71Fe29- x Sn x alloys during Sn addition with x = 0, 2, 2.5, 3, 3.85, 4.5, 6, and 10 at. pct and the solidification of these ternary alloys using SEM and TEM. These alloys have been prepared by melting high-purity elements using vacuum arc melting furnace under high-purity argon atmosphere. This was followed by suction casting these alloys in the water-cooled split Cu molds of diameters, ϕ = 1 and 3 mm, under argon atmosphere. The results indicate the formation of binary eutectic between bcc solid solution β-Ti and B2 FeTi in all alloys. β-Ti undergoes eutectoid transformation, β-Ti → α-Ti + FeTi, during subsequent solid-state cooling, leading to formation of hcp α-Ti and FeTi. For alloys x < 2, the primary FeTi forms from the liquid before the formation of eutectic with minute scale Ti3Sn phase. For alloys with 2 ≥ x ≤ 10, the liquid is found to undergo ternary quasi-peritectic reaction with primary Ti3Sn, L+Ti3Sn → β-Ti+FeTi, leading to formation of another kind of FeTi. In all the other alloy compositions (3.85 ≥ x ≤ 10), Ti3Sn and FeTi dendrites are observed in the suction cast alloys with profuse amount of Ti3Sn being formed for alloys with x ≥ 4.5. The current study conclusively proves that the liquid undergoes ternary quasi-peritectic reaction involving four phases, L + Ti3Sn → β-Ti + FeTi, which lies at the invariant point Ti69.2±0.8Fe27.4±0.7Sn3.4±0.2 (denoted by P). Below P, there is one univariant reaction, i.e., L → β-Ti + FeTi for all alloy compositions, whereas above P, liquid undergoes one of the univariant reactions, i.e., L + β-Ti → Ti3Sn (Sn = 2, 2.5, 3, and 4.5 at. pct) or L + FeTi → Ti3Sn for alloys (Sn = 6, 10 at. pct). For alloy with Sn = 3.85 at. pct, the ternary quasi-peritectic reaction is co-operated by two monovariant eutectic reactions, i.e., L → β-Ti + FeTi below P and L → Fe

  5. 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.

  6. Nanosecond Time Resolved Electron Diffraction Studies of the (Alpha) to (Beta) Transition in Pure Ti Thin Films using the Dynamic Transmission Electron Microscope (DTEM)

    SciTech Connect

    LaGrange, T; Campbell, G H; Colvin, J D; Reed, B; King, W E

    2005-12-09

    The transient events of the {alpha}-{beta} martensitic transformation in nanocrystalline Ti films were explored via single shot electron diffraction patterns with 1.5 ns temporal resolution. The diffraction patterns were acquired with a newly constructed dynamic transmission electron microscope (DTEM), which combines nanosecond pulsed laser systems and pump-probe techniques with a conventional TEM. With the DTEM, the transient events of fundamental material processes, that are far too fast to be studied by conventional bulk techniques, can be captured in the form of electron diffraction patterns or images with nanosecond temporal resolution. The transient phenomena of the martensitic transformations in nanocrystalline Ti is ideally suited for study in the DTEM, with their rapid nucleation, characteristic interface velocities {approx}1 km/s, and significant irreversible microstructural changes. Free-standing 40-nm-thick Ti films were laser-heated at a rate of {approx}10{sup 10} K/s to a temperature above the 1155 K transition point, then probed at various time intervals with a 1.5-ns-long, intense electron pulse. Diffraction patterns show an almost complete transition to the {beta} phase within 500 ns. Postmortem analysis (after the sample is allowed to cool) shows a reversion to the {alpha} phase coupled with substantial grain growth, lath formation, and texture modification. The cooled material also shows a complete lack of apparent dislocations, suggesting the possible importance of a ''massive'' short-range diffusion transformation mechanism.

  7. Study of semiconductor valence plasmon line shapes via electron energy-loss spectroscopy in the transmission electron microscope

    SciTech Connect

    Kundmann, M.K.

    1988-11-01

    Electron energy-loss spectra of the semiconductors Si, AlAs, GaAs, InAs, InP, and Ge are examined in detail in the regime of outer-shell and plasmon energy losses (0--100eV). Particular emphasis is placed on modeling and analyzing the shapes of the bulk valence plasmon lines. A line shape model based on early work by Froehlich is derived and compared to single-scattering probability distributions extracted from the measured spectra. Model and data are found to be in excellent agreement, thus pointing the way to systematic characterization of the plasmon component of EELS spectra. The model is applied to three separate investigations. 82 refs.

  8. 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.

  9. Effect of various concentrations of tetracycline hydrochloride demineralization on root dentin surface: A scanning electron microscopic study

    PubMed Central

    Penmatsa, Tanuja; Varma, Satish; Mythili; Rao, Killi Prabhakar; Kishore, Trinath; Bindu, Hima

    2013-01-01

    Introduction: Within the last 20 years root demineralization has attracted attention as a periodontal regenerative technique. Topical tetracycline application has been widely reported for use as a conditioner, to decontaminate the root surface and to promote periodontal regeneration. The purpose of this scanning electron microscopic (SEM) study is to evaluate the surface characteristics of demineralized diseased and non-diseased dentine root surfaces using different concentrations of tetracycline hydrochloride (TTC-HCl). Material and Methods: This SEM study was carried out in 20 dentin samples obtained from non-diseased human premolars and 20 dentin samples obtained from diseased human premolars. Pure TTC-HCl was applied to the dentin surface at 50 mg/ml, 100 mg/ml and 150 mg/ml concentrations for 3 min in experimental groups while distilled (0 mg/ml) water was applied to the control groups. Statistical Analysis: Mean and standard deviation were estimated from the sample for each study group. Mean values were compared by either one-way ANOVA with Tukey-Honestly significant difference procedure or Kruskal - Wallis one way ANOVA with Mann-Whitney u-test. Further Student′s independent t-test/Mann-Whitney u-test was used appropriately to compare the mean values between two independent groups. Results: In the present study using 100 mg/ml tetracycline seems to be more effective on both diseased and non-diseased dentin surfaces. Conclusions: The results of this study confirm that pure TTC-HCl conditioning produced comparable surface characteristics on dentin of both diseased and non-diseased roots with 100 mg/ml concentration for 3 min. PMID:23946576

  10. 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.

  11. [Electron-microscopic studies on fine structure and enzyme activity in the axenic and conventional strains of Entamoeba histolytica

    PubMed

    Yong, Tai Soon; Chung, Pyung Rim; Lee, Keun Tae

    1985-12-01

    The metabolism of Entamoeba histolytica would be affected by various environmental factors, and alteration of the environment was known to affect the fine structure of E. histolytica. The present study was designed electronmicroscopically to investigate the ultrastructure and enzyme activities in the axenic and conventional strains of E. histolytica. The trophozoites of axenically cultivated HK-9 strain and conventional YS-27 and YS-49 strains of E. histolytica were collected and fixed with 4 percent paraformaldehyde/0.1 M cacodylate buffer (pH 7.4). After washing them by centrifugation, 1 percent warm agar was added in the sediment. Solidified agar with the trophozoites was cut into 1 mm(3) cubes, and incubated in the various substrates to observe enzyme activities. Then, the specimen was post-fixed with 3 percent glutaraldehyde/0.1 M cacodylate buffer (pH 7.4) and 1 percent osmium tetroxide/0.1 M cacodylate buffer (pH 7.4), dehydrated in ascending ethanol series and embedded in epoxy resin. These were sectioned on an ultramicrotome and observed with a transmission electron microscope. The procedures for the observation of the fine structure were same as the above, except for the incubation in the substrate. The sections were stained with uranyl scetate and lead citrate. For the observation of the surface of the amoebae, scanning electron microscopy was carried out. The results obtained in the present study are summarized as follows: 1. The fuzzy coat around double-layered plasma membrane of E. histolytica was more irregularly and densely distributed in the conventional strains (YS-27, YS-49 strains) than in the axenic strain (HK-9 strain). 2. The endosomes, button bodies and chromatin material were surrounded by a double-layered nuclear membrane having scattered nuclear pores. The paranuclear body, mono- or double-layered vacuoles, vacuolar membrane whorls, rosette-like cylindrical bodies, aggregation of cylindrical bodies and helical bodies were found in the

  12. 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…

  13. Transmission Electron Microscope Measures Lattice Parameters

    NASA Technical Reports Server (NTRS)

    Pike, William T.

    1996-01-01

    Convergent-beam microdiffraction (CBM) in thermionic-emission transmission electron microscope (TEM) is technique for measuring lattice parameters of nanometer-sized specimens of crystalline materials. Lattice parameters determined by use of CBM accurate to within few parts in thousand. Technique developed especially for use in quantifying lattice parameters, and thus strains, in epitaxial mismatched-crystal-lattice multilayer structures in multiple-quantum-well and other advanced semiconductor electronic devices. Ability to determine strains in indivdual layers contributes to understanding of novel electronic behaviors of devices.

  14. 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.

  15. 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.

  16. 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

  17. Marginal sealing ability of silorane and methacrylate resin composites in class II cavities: A scanning electron microscopic study

    PubMed Central

    Nanjundasetty, Jyothi Kashi; Nanda, Soumyaranjan; Panuganti, Venugopal; Marigowda, Jayashankar Chatra

    2013-01-01

    Aim and Objectives: To comparatively evaluate the microleakage and microgap formation along the gingival margin in class II cavities restored with silorane resin composite and methacrylate resin composite with and without flowable resin liner. Materials and Methods: Sixty human mandibular premolars were distributed into three groups, each group containing 20 teeth (n = 20). Mesial (subgroup A) and distal (subgroup B) box cavities were prepared with gingival margin above and below cemento enamel junction (CEJ), respectively, in each tooth and restored as follows — Group I — Silorane resin composite with self-etch primer and bond (Filtek P90, 3M ESPE MN, USA). Group II — Methacrylate resin composite (Filtek P60, 3M ESPE MN, USA) and self-etch adhesive (Adper Easy one, 3M ESPE MN, USA). Group III — Methacrylate resin composite with self-etch adhesive and a flowable resin liner (Filtek Z350 XT, 3M ESPE MN, USA). The teeth were thermocycled and immersed in 50% silver nitrate solution before sectioning. The specimens were observed under scanning electron microscope for dye penetration and microgap formation. The data was subjected to statistical analysis using Kruskal-Wallis test and Mann-Whitney U test using SPSS version 18. Results: Subgroup A in all the three groups showed significantly less microleakage and microgap formation compared to subgroup B with P < 0.05. Intergroup comparison of subgroup A did not show statistically significant difference, whereas subgroup B showed statistically significant difference for microleakage between group I and group II (P = 0.003), group III and group II (P = 0.002). Conclusion: Silorane resin composite and methacrylate resin with liner showed significantly less microleakage in class II cavities along the gingival margin placed below CEJ compared to methacrylate resin without liner. All the study groups showed less microleakage and microgap formation along the gingival margin placed above CEJ. PMID:24347882

  18. In vitro bonding effectiveness of self-etch adhesives with different application techniques: A microleakage and scanning electron microscopic study

    PubMed Central

    Nagpal, Rajni; Manuja, Naveen; Tyagi, Shashi Prabha; Singh, Udai Pratap

    2011-01-01

    Aim: To evaluate and compare the microleakage of self-etch adhesives placed under different clinical techniques and to analyze the resin–dentin interfacial ultrastructure under scanning electron microscope (SEM). Materials and Methods: 100 extracted human premolars were divided into two groups for different adhesives (Clearfil S3 and Xeno III). Class V cavities were prepared. Each group was further divided into four subgroups (n = 10) according to the placement technique of the adhesive, i.e. according to manufacturer's directions (Group 1), with phosphoric acid etching of enamel margins (Group 2), with hydrophobic resin coat application (Group 3), with techniques of both groups 2 and 3 (Group 4). The cavities were restored with composite. Ten samples from each group were subjected to microleakage study. Five samples each of both the adhesives from groups 1 and 3 were used for SEM examination of the micromorphology of the resin–dentin interface. Results: At enamel margins for both the adhesives tested, groups 2 and 4 showed significantly lesser leakage than groups 1 and 3. At dentin margins, groups 3 and 4 depicted significantly reduced leakage than groups 1 and 2 for Xeno III. SEM observation of the resin–dentin interfaces revealed generalized gap and poor resin tag formation in both the adhesives. Xeno III showed better interfacial adaptation when additional hydrophobic resin coat was applied. Conclusions: In enamel, prior phosphoric acid etching reduces microleakage of self-etch adhesives, while in dentin, hydrophobic resin coating over one-step self-etch adhesives decreases the microleakage. PMID:22025829

  19. A Comparative Evaluation of Adherence of Microorganism to Different Types of Brackets: A Scanning Electron Microscopic Study

    PubMed Central

    Shashidhar, E P; Sahitya, M; Sunil, T; Murthy, Anup R; Rani, M S

    2015-01-01

    Background: The purpose of this study was to evaluate and compare the adherence of microorganism to different types of brackets using the scanning electron microscope (SEM). A double-blinded study was undertaken to evaluate and adherence of microorganisms to different types of brackets using SEM. Materials and Methods: At random, 12 patients reporting for treatment to the department of Orthodontics VS Dental College and Hospital were selected. Four types of brackets were included in the present study stainless steel, titanium, composite, and ceramic. Brackets were bonded to teeth of the patient on all the four quadrants. The teeth included for bonding were lateral incisor, canine, first premolar, and second premolar. The brackets were left for 72 h. After 72 h brackets were debonded, and they were evaluated by SEM for adherence of microorganism in the slot and tie wings surface. The SEM images were graded, and the adherence of microorganism to the brackets in the surfaces and the four different quadrants were recorded. Results: There is a significant difference in adherence of microorganisms to the various types of brackets (P < 0.001) and the surfaces (P < 0.05) included in the study. However, there is no significance in the mean adherence of microorganisms in the different quadrants (P > 0.05) included in the study. The interaction of bracket/surface, bracket/quadrant, surface/quadrants was analyzed, there was no significance of comparison of bracket/surfaces/quadrant but the interaction of bracket/quadrant was found to be significant (<0.011). The interaction of bracket/surfaces/quadrant was also found to be significant (<0.003). Conclusion: The maximum adherence of microorganisms was observed with the composite bracket material and the least adherence of microorganisms was observed with the titanium bracket material. The adherence of microorganisms is relatively more in the slot area, when compare to the tie wings surface maximum adherence of microorganism is

  20. 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.

  1. Comparative biochemical and electron-microscopic study of membrane damage to the endoplasmic reticulum by a chemical carcinogen in vivo and in vitro

    SciTech Connect

    Merkur'eva, R.V.; Dolinskaya, S.I.; Shekhtman, A.B.; Gasanov, T.G.; Gadzhieva, T.I.; Shakmirova, S.F.

    1987-07-01

    Results are given of a comparative biochemical and electron-microscopic study of the membrane-damaging action of the chemical carcinogen N-nitrosodimethylamine (NDMA), as a result of exposure in vivo and in vitro. Experiments were carried out on rats. A characteristic feature of development of the biological effect of NDMA both in vivo and in vitro is a decrease in activity of the membrane-bound enzymes of the endoplasmic reticulum chosen for study.

  2. In-situ deformation studies of an aluminum metal-matrix composite in a scanning electron microscope

    NASA Technical Reports Server (NTRS)

    Manoharan, M.; Lewandowski, J. J.

    1989-01-01

    Tensile specimens made of a metal-matrix composite (cast and extruded aluminum alloy-based matrix reinforced with Al2O3 particulate) were tested in situ in a scanning electron microscope equipped with a deformation stage, to directly monitor the crack propagation phenomenon. The in situ SEM observations revealed the presence of microcracks both ahead of and near the crack-tip region. The microcracks were primarily associated with cracks in the alumina particles. The results suggest that a region of intense deformation exists ahead of the crack and corresponds to the region of microcracking. As the crack progresses, a region of plastically deformed material and associated microcracks remains in the wake of the crack.

  3. 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.

  4. Deformation mechanisms in free-standing nanoscale thin films: a quantitative in situ transmission electron microscope study.

    PubMed

    Haque, M A; Saif, M T A

    2004-04-27

    We have added force and displacement measurement capabilities in the transmission electron microscope (TEM) for in situ quantitative tensile experimentation on nanoscale specimens. Employing the technique, we measured the stress-strain response of several nanoscale free-standing aluminum and gold films subjected to several loading and unloading cycles. We observed low elastic modulus, nonlinear elasticity, lack of work hardening, and macroscopically brittle nature in these metals when their average grain size is 50 nm or less. Direct in situ TEM observation of the absence of dislocations in these films even at high stresses points to a grain-boundary-based mechanism as a dominant contributing factor in nanoscale metal deformation. When grain size is larger, the same metals regain their macroscopic behavior. Addition of quantitative capability makes the TEM a versatile tool for new fundamental investigations on materials and structures at the nanoscale. PMID:15084745

  5. 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.

  6. 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.

  7. Computerized analytical electron microscope for elemental imaging

    NASA Astrophysics Data System (ADS)

    Gorlen, K. E.; Barden, L. K.; Del Priore, J. S.; Fiori, C. E.; Gibson, C. C.; Leapman, R. D.

    1984-06-01

    A computer system has been interfaced to an analytical scanning transmission electron microscope (STEM) to form an integrated system for high-resolution mapping of the elemental constituents of a specimen. The system controls the electron beam position, acquires data from electron energy-loss spectroscopy (EELS) and energy dispersive x-ray spectroscopy (EDS) detectors, and constructs elemental images by analyzing EELS and EDS spectra taken at each pixel. Data also are acquired and digitized from conventional STEM bright-field and dark-field detectors. Since image registration errors are eliminated by acquiring data from all detectors concurrently, elemental distribution images obtained from energy-loss and x-ray detectors can be correlated with morphological images taken from bright-field and dark-field detectors. Energy-loss and x-ray spectra of user-defined target areas can also be obtained. Data can be acquired, processed, and displayed at the same time because a satellite microcomputer interfaced to the microscope does much of the data acquisition, freeing the host computer to subtract the spectral background from the electron energy-loss and x-ray data ``on the fly,'' and also to display dynamically the background corrected energy-loss spectrum at each image pixel. Such a display is important for correct operation of the instrument and interpretation of the results. Images are displayed on a color display system equipped with a digital video array processor, where they can be enhanced, compared, measured, annotated, and photographed. Operation of the system is simplified by using menus for function selection and by filling out forms displayed on a video terminal to enter data-acquisition and processing parameters. The computer-controlled analytical electron microscope is used to provide elemental distributions from thin specimens in biology and materials science. Results show that concentrations of a few atomic percent can be mapped at a resolution of 10 to 20

  8. Characterizing wear with the scanning electron microscope

    SciTech Connect

    Lee, R.H.

    1991-07-01

    The Scanning Electron Microscope (SEM) is used extensively to characterize and analyze wear mechanisms and coatings on material. Wear mechanisms and severity can be identified by the characteristic scars on sample surfaces and by examining wear debris. Backscattered electron imaging is very useful in identifying oxidized materials and locations where coatings have worn thin. These images are compared with spectra from energy-dispersive X-ray spectroscopy or wavelength-dispersive spectroscopy data to verify the identifications. Micrographs of typical wear mechanisms are presented and techniques for analysis of wear surfaces are discussed. Examples of the evaluation of coatings are also presented and an ultramicrohardness tester installed in the SEM to evaluate coating hardness and fracture toughness is described. 3 refs., 15 figs.

  9. Structure and Dynamics with Ultrafast Electron Microscopes

    NASA Astrophysics Data System (ADS)

    Siwick, Bradley

    In this talk I will describe how combining ultrafast lasers and electron microscopes in novel ways makes it possible to directly `watch' the time-evolving structure of condensed matter, both at the level of atomic-scale structural rearrangements in the unit cell and at the level of a material's nano- microstructure. First, I will briefly describe my group's efforts to develop ultrafast electron diffraction using radio- frequency compressed electron pulses in the 100keV range, a system that rivals the capabilities of xray free electron lasers for diffraction experiments. I will give several examples of the new kinds of information that can be gleaned from such experiments. In vanadium dioxide we have mapped the detailed reorganization of the unit cell during the much debated insulator-metal transition. In particular, we have been able to identify and separate lattice structural changes from valence charge density redistribution in the material on the ultrafast timescale. In doing so we uncovered a previously unreported optically accessible phase/state of vanadium dioxide that has monoclinic crystallography like the insulator, but electronic structure and properties that are more like the rutile metal. We have also combined these dynamic structural measurements with broadband ultrafast spectroscopy to make detailed connections between structure and properties for the photoinduced insulator to metal transition. Second, I will show how dynamic transmission electron microscopy (DTEM) can be used to make direct, real space images of nano-microstructural evolution during laser-induced crystallization of amorphous semiconductors at unprecedented spatio-temporal resolution. This is a remarkably complex process that involves several distinct modes of crystal growth and the development of intricate microstructural patterns on the nanosecond to ten microsecond timescales all of which can be imaged directly with DTEM.

  10. 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

  11. An electron microscopic radioautographic study of collagen secretion in periodontal ligament fibroblasts of the mouse: I. Normal fibroblasts

    SciTech Connect

    Cho, M.I.; Garant, P.R.

    1981-12-01

    Analysis of electron microscopic radioautographs revealed a maximum labeling with /sup 3/H-proline of rough endoplasmic reticulum (RER) at 3 minutes, Golgi saccules 1 and 2 at 10 minutes, Golgi saccules type 3 at 20 minutes, and presecretory and secretory granules at 30 minutes. Labeling of the extra-cellular collagen matrix occurred at 30 minutes and increased with time. These observations suggest that pro-a-chains of collagen in periodontal ligament fibroblasts are synthesized in the RER and transported to the Golgi apparatus within 10 minutes. These chains then undergo parallel alignment in Golgi saccules type 2 and form segment-long-spacing-like crystallites in Golgi saccules type 3 between 10 and 20 minutes. The peak labeling of presecretory granules and mature secretory granules in small amounts at 30 minutes and the rapid increase in labeling of extracellular collagen matrix which begins at 30 minutes, indicates that the formation of secretory granules requires approximately 30 minutes and that a rapid system of secretory granule translocation exists in periodontal ligament fibroblasts. This evidence further supports the previously published morphologic evidence for a microtubule-dependent system of collagen secretion in periodontal ligament fibroblasts (Cho and Garant, 1981b).

  12. Synaptic interactions of retrogradely labeled hypoglossal motoneurons with substance P-like immunoreactive nerve terminals in the cat: a dual-labeling electron microscopic study.

    PubMed

    Gatti, P J; Coleman, W C; Shirahata, M; Johnson, T A; Massari, V J

    1996-07-01

    This study has investigated the synaptic interactions between hypoglossal motoneurons and substance P (SP)-immunoreactive terminals. Cholera toxin B conjugated to horseradish peroxidase was injected into the tip of the tongue on the right side of six ketamine-anesthetized cats. Two to five days later, the animals were killed. Cells containing HRP were labeled with a histochemical reaction utilizing tetramethylbenzidine (TMB) as the chromogen. TMB forms crystalline reaction products that are very distinct at the electron microscopic level. The tissues were then processed for immunocytochemistry using an antiserum against SP. The chromogen used in this case, diaminobenzidine, yields amorphous reaction products. At the light microscopic level, labeled cells were observed primarily ipsilaterally in both intermediate and ventrolateral subdivisions of the hypoglossal nucleus. The majority of these labeled cells were seen at the level of obex. At the electron microscopic level, both asymmetric and symmetric synapses were observed. SP-immunoreactive nerve terminals formed asymmetric synapses with labeled dendrites and symmetric synapses with labeled perikarya. SP-labeled terminals also synapsed on unlabeled dendrites and somata. These are the first ultrastructural studies demonstrating synaptic interactions between hypoglossal motoneurons and SP terminals. These studies demonstrate that hypoglossal motoneurons that innervate intrinsic tongue muscles are modulated by SP and that SP may play a role in the control of fine movements of the tongue. PMID:8836682

  13. [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

  14. 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

  15. 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

  16. Electron Gun Technologies for High Resolution Electron Microscopes

    NASA Astrophysics Data System (ADS)

    Fujita, Shin

    High-brightness electron gun technologies for high resolution electron microscopes are reviewed. High performance electron beam apparatuses today are equipped with either Schottky emission or field emission type cathodes, both of which have sharply etched tips for electric field enhancement that promotes electron emission. One of the key elements in these pointed cathodes is a proper control of the tip geometry. It substantially affects the emitter optics and performance. It is shown that the geometry is dictated by the faceting of the tip, which is in turn determined by the Equilibrium Crystal Shape (ECS). The ECS is the tip geometry that minimizes the surface free energy and dependent on the emitter operation environment. By proper choice of the tip field and temperature, one can control the degree of faceting and achieve optically desirable tip geometries.

  17. Total energy study of the microscopic structure and electronic properties of tetragonal perovskite SrTiO{sub 3}

    SciTech Connect

    Rubio-Ponce, A.; Olguín, D.

    2014-05-15

    To study the structural and electronic properties of cubic perovskite SrTiO{sub 3} and its stress-induced tetragonal phase, we have performed total energy calculations and studied the effect of oxygen vacancies on the electronic properties of tetragonal perovskite SrTiO{sub 3}. The method used was the relativistic full-potential linearized augmented plane wave (FLAPW) method. To obtain the geometry that minimizes the total energy, we relaxed the internal atomic sites of the tetragonal cell. As a result of this procedure, we have found that the titanium atoms move toward the plane of the vacancy by 0.03 Å, and the apical oxygen atoms move to the same plane by approximately 0.14 Å. These results are discussed in comparison with experimental data.

  18. A comparative evaluation of smear layer removal by using edta, etidronic acid, and maleic acid as root canal irrigants: An in vitro scanning electron microscopic study

    PubMed Central

    Kuruvilla, Aby; Jaganath, Bharath Makonahalli; Krishnegowda, Sahadev Chickmagaravalli; Ramachandra, Praveen Kumar Makonahalli; Johns, Dexton Antony; Abraham, Aby

    2015-01-01

    Aim: The purpose of this study is to evaluate and compare the efficacy of 17% EDTA, 18% etidronic acid, and 7% maleic acid in smear layer removal using scanning electron microscopic image analysis. Materials and Methods: Thirty, freshly extracted mandibular premolars were used. The teeth were decoronated to obtain working length of 17mm and instrumentation up to 40 size (K file) with 2.5% NaOCl irrigation between each file. The samples were divided into Groups I (17% ethylenediaminetetraacetic acid (EDTA)), II (18% etidronic acid), and III (7% maleic acid) containing 10 samples each. Longitudinal sectioning of the samples was done. Then the samples were observed under scanning electron microscope (SEM) at apical, middle, and coronal levels. The images were scored according to the criteria: 1. No smear layer, 2. moderate smear layer, and 3 heavy smear layer. Statistical Analysis: Data was analyzed statistically using Kruskal–Wallis analysis of variance (ANOVA) followed by Mann-Whitney U test for individual comparisons. The level for significance was set at 0.05. Results: The present study showed that all the three experimental irrigants removed the smear layer from different tooth levels (coronal, middle, and apical). Final irrigation with 7% maleic acid is more efficient than 17% EDTA and 18% etidronic acid in the removal of smear layer from the apical third of root canal. PMID:26069414

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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

  4. The trajectories of secondary electrons in the scanning electron microscope.

    PubMed

    Konvalina, Ivo; Müllerová, Ilona

    2006-01-01

    Three-dimensional simulations of the trajectories of secondary electrons (SE) in the scanning electron microscope have been performed for plenty of real configurations of the specimen chamber, including all its basic components. The primary purpose was to evaluate the collection efficiency of the Everhart-Thornley detector of SE and to reveal fundamental rules for tailoring the set-ups in which efficient signal acquisition can be expected. Intuitive realizations about the easiness of attracting the SEs towards the biased front grid of the detector have shown themselves likely as false, and all grounded objects in the chamber have been proven to influence the spatial distribution of the signal-extracting field. The role of the magnetic field penetrating from inside the objective lens is shown to play an ambiguous role regarding possible support for the signal collection. PMID:17063762

  5. X-ray diffraction and electron microscope studies of yttria stabilized zirconia (YSZ) ceramic coatings exposed to vanadia. Master's thesis

    SciTech Connect

    Kondos, K.G.

    1992-09-01

    The U.S. Navy sometimes has the requirement to use low cost fuels containing significant amounts of vanadium and sulfur in gas turbine engines. Unfortunately the yttria stabilized zirconia (YSZ) witch is used as a thermal barrier coating on gas turbine blades can be severely attacked by vanadia. Powders of YSZ containing 8-mol% Y203 and pure zirconia containing various and mounts Of V205 were annealed at 900 deg. C. These were then examined by X-ray diffraction and electron microscopy, as well as single crystals of pure Zro2 and YSZ ( 20% Wt Y203 ) exposed to V205 Melts, to study how the vanadia degrades the YSZ by reacting with the stabilizer to form YVO4 and how the vanadium transforms the cubic and tetragonal YSZ crystal structures to monoclinic which degrades rapidly as a gas turbine blade coating.

  6. Electron microscopic study on macrogametogenesis of Eimeria labbeana infecting the Egyptian wild doves and host-parasite relationship.

    PubMed

    Bashtar, A R; Abdel-Ghaffar, F A; Ahmed, A K

    1991-04-01

    The development of macrogametes of Eimeria labbeana was studied by electron microscopy in the epithelial cells of the villi at 96 hrs. post-infection. Appearance of young macrogamonts was characterized by the loss of the architecture of the apicomplexa (polar ring, rhoptries, micronemes, conoid, subpellicular microtubules), while the pellicle became only one unit membrane. This was associated by the formation of wall forming bodies II then I. Moreover, the mitochondria, endoplasmic reticulum and Golgi were increased in the cytoplasm. Amylopectin granules as well as lipid globules were greatly increased in mature macrogametes. Host cell reaction due to infection included enlargement and deformation of infected cells, hypertrophy of their nuclei, swollen and degeneration of mitochondria, endoplasmic reticulum and vacuolation of ground cytoplasm. These changes occur in both cells with and without parasite. PMID:2033300

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. Evaluation of periimplant bone neoformation using different scanning electron microscope methods for measuring BIC. A dog study

    PubMed Central

    Aguilar-Salvatierra, Antonio; Guardia, Javier; Delgado-Ruiz, Rafael; Ramírez-Fernández, María P.; Pérez Sánchez, Cristina; Gómez-Moreno, Gerardo

    2012-01-01

    Objetives: The aim of this study was to determine which of three methods for measuring BIC (bone-to-implant contact), using vestibular and lingual scanning electron microscopy (SEM) for different implant systems at 15, 30 and 90 days post-surgery was the most precise. An elemental analysis with SEM was used to evaluate neoformed bone composition for three implant systems at the same study times. Material and Methods: 36 implants were placed in eighteen Beagle dogs mandible about one year old and weighing approximately 12-13 kg in order to evaluate bone apposition to three different implant surfaces. It was used the third and fourth premolar and first molar distal sockets in both quadrants of the mandible (3P3, 4P4 and 1M1). Teeth were hemi-sected and the distal roots were removed. The specimens were prepared for histological examination and each section surface was stained using Masson’s trichrome and hematoxylin and eosin stains. BIC evaluations were performed by the three methods, BIC I (the quantity of mineralized bone in direct contact with the implant’s titanium surface across the entire threaded area); BIC II (along a line that passes from apex to apex of the implant threads); BIC III (both in areas around and above the threads and in between threads). Results: Both BIC and bone content were analyzed for all implants placed in P3, P4 y M1 alveoli on both, the buccal and palatine sides (elemental analysis quantified Ca, P, O and C). It was seen it was only at the ninety-day mark that high percentages of calcium were present. Conclusions: This study suggest that BIC III evaluation is the most certain method for establishing the quantity of bone formed as the BIC area. Key words:Bone-to-impant contact, dogs, extraction socket, implants. PMID:24558531

  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. The influence of diet and dimethylhydrazine on the large intestine of vervet monkeys: scanning and transmission electron microscope studies.

    PubMed Central

    Jaskiewicz, K.; Kritchevsky, D.; Venter, F. S.; van Wyk, W. E.

    1987-01-01

    The study was designed to identify diet and carcinogen-dependent ultrastructural changes in the epithelium of macroscopically normal colonic mucosa in primates. Seventy adult female vervet monkeys were divided into seven equal treatment groups. Four received a Western high-fat low fibre diet (WD), two a prudent low-fat higher fibre diet (PD) and one a control low-fat high fibre diet (CD). Three groups (2 WD, 1 PD) received dimethylhydrazine intramuscularly at 14 day intervals. After 18 months, monkeys of two groups on the WD were transferred to the PD (WD----PD) and 30 months later all were killed. Mucosae of caecum, colon transversum and rectum were examined by scanning and transmission electron microscopy and showed close similarity to that of humans. Rectal mucosae showed increased surface goblet cell secretory activity, mucin production and microvillar changes related to WD and WD----PD. The enhancing effect of a carcinogen on ultrastructural changes such as cellular pleomorphism, cytoplasmic interbridging, nuclear and nucleolar irregularities and appearance of argentaffin cells in the free surface epithelium were noted predominantly in high-fat treated animals. Such changes observed in the upper part of crypt, orifice and free surface epithelium can be characteristic for precancerous change and could be utilised practically in the detection of precursor lesions of the colon. Images Fig. 9 Fig. 10 Figs. 11 & 12 Fig. 1 Fig. 2 Fig. 3 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Figs. 13 & 14 PMID:3620336

  14. 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.

  15. 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. PMID:15108154

  16. 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.

  17. A Scanning Electron Microscope Study on the Effect of an Experimental Irrigation Solution on Smear Layer Removal

    PubMed Central

    Zand, Vahid; Mokhtari, Hadi; Lotfi, Mehrdad; Rahimi, Saeed; Sohrabi, Aydin; Badamchi Zadeh, Sina; Mojaver Kahnamooie, Hanieh; Tehranchi, Pardis

    2014-01-01

    Introduction: The aim of this in vitro study was to evaluate the effect of an experimental irrigation solution, containing two different concentrations of papain, Tween 80, 2% chlorhexidine and EDTA, on removal of the smear layer. Methods and Materials: Thirty-six single-rooted teeth were divided into two experimental groups (n=12) and two positive and negative control groups of six. The canals were prepared with BioRaCe instruments up to BR7 (60/0.02). In group 1, canals were irrigated with a combination of 1% papain, 17% EDTA, Tween 80 and 2% CHX; in group 2, canals were irrigated with a combination of 0.1% papain, 17% EDTA, Tween 80 and 2% CHX. In group 3 (the negative control), the canal was irrigated with 2.5% NaOCl during instrumentation and at the end of preparation with 1 mL of 17% EDTA was used; in group 4 (positive control), normal saline was used for irrigation. The amount of the remaining smear layer was quantified according to Hulsmann method using scanning electron microscopy (SEM). Data was analyzed by the Kruskal-Wallis and Mann-Whitney tests. Results: Two-by-two comparisons of the groups revealed no significant differences in terms of smear layer removal at different canal sections between the negative control group (standard regiment for smear layer removal) and 1% papain groups (P<0.05). Conclusion: Under the limitations of the present study, combination of 1% papain, EDTA, 2% chlorhexidine and Tween 80 can effectively remove smear layer from canal walls. PMID:24688583

  18. Distribution of axon diameters in cortical white matter: an electron-microscopic study on three human brains and a macaque.

    PubMed

    Liewald, Daniel; Miller, Robert; Logothetis, Nikos; Wagner, Hans-Joachim; Schüz, Almut

    2014-10-01

    The aim of this study was to obtain information on the axonal diameters of cortico-cortical fibres in the human brain, connecting distant regions of the same hemisphere via the white matter. Samples for electron microscopy were taken from the region of the superior longitudinal fascicle and from the transitional white matter between temporal and frontal lobe where the uncinate and inferior occipitofrontal fascicle merge. We measured the inner diameter of cross sections of myelinated axons. For comparison with data from the literature on the human corpus callosum, we also took samples from that region. For comparison with well-fixed material, we also included samples from corresponding regions of a monkey brain (Macaca mulatta). Fibre diameters in human brains ranged from 0.16 to 9 μm. Distributions of diameters were similar in the three systems of cortico-cortical fibres investigated, both in humans and the monkey, with most of the average values below 1 μm diameter and a small population of much thicker fibres. Within individual human brains, the averages were larger in the superior longitudinal fascicle than in the transitional zone between temporal and frontal lobe. An asymmetry between left and right could be found in one of the human brains, as well as in the monkey brain. A correlation was also found between the thickness of the myelin sheath and the inner axon diameter for axons whose calibre was greater than about 0.6 μm. The results are compared to white matter data in other mammals and are discussed with respect to conduction velocity, brain size, cognition, as well as diffusion weighted imaging studies. PMID:25142940

  19. A scanning electron microscope study on the route of entry of clorsulon into the liver fluke, Fasciola hepatica.

    PubMed

    Meaney, M; Haughey, S; Brennan, G P; Fairweather, I

    2005-01-01

    Three experiments were carried out in vitro to determine the roles of the tegument and gut of Fasciola hepatica in the uptake of the flukicidal drug, clorsulon. Changes to the two surfaces were assessed by scanning electron microscopy. In the first experiment, the flukes were ligatured to prevent the oral ingestion of drug and treated for 24 h in clorsulon (10 microg/ml). The gastrodermal surface remained normal and few changes to the tegumental surface were observed. In the second experiment, flukes were fed for 24 h on red blood cells isolated from rats dosed with clorsulon at 12.5 mg/kg body weight; this experiment was designed to prevent the exposure of the tegumental surface to the drug. The gastrodermal surface was severely disrupted and the gut lamellae were disorganised and necrotic. Swelling of the tegument and blebbing on the tegumental surface were evident, but the changes were not severe. More severe swelling of the tegument was observed in the third experiment, in which flukes were incubated for 24 h in clorsulon (10 microg/ml), with both absorptive surfaces being available for drug uptake. The gastrodermal surface was badly disrupted and the gut lamellae were disorganised and necrotic. Taking the results of the three experiments together, the gastrodermal surface was more affected than the tegument and the greatest disruption to the two surfaces was seen when both routes of entry were available to the fluke. The data support a previous study which indicated that entry of clorsulon into the fluke in vivo is principally by the oral ingestion of drug bound to the red blood cells. PMID:15592937

  20. Provenance study through analysis of microstructural characteristics using an optical microscope and scanning electron microscopy for Goryeo celadon excavated from the seabed.

    PubMed

    Min-su, Han

    2013-08-01

    This paper aims at identifying the provenance of Goryeo celadons by understanding its microstructural characteristics, such as particles, blisters, forms and amount of pores, and the presence of crystal formation, bodies, and glazes and its boundary, using an optical microscope and scanning electron microscopy (SEM). The analysis of the reproduced samples shows that the glazed layer of the sherd fired at higher temperatures has lower viscosity and therefore it encourages the blisters to be combined together and the layer to become more transparent. In addition, the result showed that the vitrification and melting process of clay minerals such as feldspars and quartzs on the bodies was accelerated for those samples. To factor such characteristics of the microstructure and apply it to the sherds, the samples could be divided into six categories based on status, such as small particles with many small pores or mainly large and small circular pores in the bodies, only a limited number of varied sized blisters in the glazes, and a few blisters and needle-shaped crystals on the boundary surface. In conclusion, the analysis of the microstructural characteristics using an optical microscope and SEM have proven to be useful as a categorizing reference factor in a provenance study on Goryeo celadons. PMID:23920196

  1. The evolution of cervical mucus infrastructure in normal cyclic baboons (Papio anubis) and castrated females receiving hormonal supplies. A scanning electron microscope study.

    PubMed

    Chrétien, F C

    1980-01-01

    The scanning electron microscope was used to study the evolution of the infrastructure of cervical mucus in normal cyclic baboons and in castrated animals treated with ovarian hormones for establishing an artificial cycle. In both groups, the results make conspicuous the progressive enlargement of the filamentous woof, which attains a maximum at midcycle and then decreases by degrees in the second part of the cycle. It was shown that the evolution of the framework is very similar during normal and artificial cycle, with only variations of slight amplitude. Moreover, the variations in the baboon mucus infrastructure closely resemble those described in the human. The results are briefly discussed in the light of known data. PMID:6770577

  2. The effect of two different demineralization methods with saturated tetracycline hydrochloride on the attachment and growth of gingival fibroblasts. A scanning electron microscopic study.

    PubMed

    Babay, N; Mokeem, S

    2005-03-01

    The purpose of the present study was to evaluate in vitro, the influence of two different methods of surfaces conditioning of dentin by tetracycline hydrochloride on human gingival epithelial cell attachment. A flat dentin surface was created on human teeth extracted due to severe periodontitis: 36 specimens were divided into 3 equal groups and etched in the following way: group 1 (saline); group 2 (immersion in TTC for 3 min); group 3 (burnishing with TTC for 3 min). The specimens and fibroblasts were incubated in a culture medium for 24 hours, one and two weeks and photographed using scanning electron microscope. No fibroblasts could be seen on the saline groups. More fibroblasts could attach to the root surface at one and two weeks irrespective of the method used. PMID:16032945

  3. The Natural History of Uterine Leiomyomas: Light and Electron Microscopic Studies of Fibroid Phases, Interstitial Ischemia, Inanosis, and Reclamation

    PubMed Central

    Flake, Gordon P.; Moore, Alicia B.; Sutton, Deloris; Kissling, Grace E.; Horton, John; Wicker, Benita; Walmer, David; Robboy, Stanley J.; Dixon, Darlene

    2013-01-01

    We propose, and offer evidence to support, the concept that many uterine leiomyomas pursue a self-limited life cycle. This cycle can be arbitrarily divided on the basis of morphologic assessment of the collagen content into 4 phases: (1) proliferation, (2) proliferation and synthesis of collagen, (3) proliferation, synthesis of collagen, and early senescence, and (4) involution. Involution occurs as a result of both vascular and interstitial ischemia. Interstitial ischemia is the consequence of the excessive elaboration of collagen, resulting in reduced microvascular density, increased distance between myocytes and capillaries, nutritional deprivation, and myocyte atrophy. The end stage of this process is an involuted tumor with a predominance of collagen, little to no proliferative activity, myocyte atrophy, and myocyte cell death. Since many of the dying cells exhibit light microscopic and ultrastructural features that appear distinct from either necrosis or apoptosis, we refer to this process as inanosis, because it appears that nutritional deprivation, or inanition, is the underlying cause of cell death. The disposal of myocytes dying by inanosis also differs in that there is no phagocytic reaction, but rather an apparent dissolution of the cell, which might be viewed as a process of reclamation as the molecular contents are reclaimed and recycled. PMID:24348569

  4. Method of forming aperture plate for electron microscope

    NASA Technical Reports Server (NTRS)

    Heinemann, K. (Inventor)

    1974-01-01

    An electron microscope is described with an electron source a condenser lens having either a circular aperture for focusing a solid cone of electrons onto a specimen or an annular aperture for focusing a hollow cone of electrons onto the specimen. It also has objective lens with an annular objective aperture, for focusing electrons passing through the specimen onto an image plane. A method of making the annular objective aperture using electron imaging, electrolytic deposition and ion etching techniques is included.

  5. Electron microscopic ultrastructural study on the toxicological effects of AgNPs on the liver, kidney and spleen tissues of albino mice.

    PubMed

    Ansari, Mohammad Azam; Shukla, Arun Kumar; Oves, Mohammad; Khan, Haris M

    2016-06-01

    The present study deals with the intraperitoneal administration of 500, 1000, 3000, and 5000mg/kg of AgNPs in albino mice for 28 days to evaluate the potential toxicological effects of AgNPs on blood biochemical parameters and to investigate the light and electron microscopic histopathological alterations on three major targets organs i.e., liver, kidney and spleen. The AgNPs was well tolerated and no mortality was observed even at the highest dose i.e., 5000mg/kg. Mice treated with 500 and 1000mg/kg AgNPs did not show significant behavioral, biochemical and ultrastructural pathological changes. Mice treated with 1000mg/kg AgNPs produces little ultrastructural alteration in liver, kidney and spleen. However, mice treated with 3000 and 5000mg/kg AgNPs revealed significant changes in biochemical parameters. Electron microscopic ultrastructural investigation of liver and kidney shows that the administration of 3000 and 5000mg/kg AgNPs revealed irregularity in the nuclear membrane, nuclear chromatin condensations, degenerated hepatocytes, swollen and pleomorphic mitochondria with distorted cristae, extensive dilation of rough endoplasmic reticulum, destructed cytoplasm, hypertrophied and fused podocytes and thickened basement membrane in the endothelial cells of the proximal tubules. The spleen sections at 3000 and 5000mg/kg AgNPs revealed megakaryocytes hyperplasia, lobulations, invaginations and folding of nuclei and nuclear membrane. The present research indicates that AgNPs were well tolerated at the lower doses, but significant alterations in liver, kidney and spleen were observed at the higher doses tested. It is, therefore, suggested that further studies are needed for the minimization of the observed side effects, especially at higher doses before AgNPs being applied in pharmaceutical application. PMID:27100208

  6. 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…

  7. Light and electron microscopic study of mature spermatozoa from White Pekin duck (Anas platyrhynchos): an ultrastructural and molecular analysis.

    PubMed

    Majhi, Rakesh Kumar; Kumar, Ashutosh; Yadav, Manoj; Kumar, Pradeep; Maity, Apratim; Giri, Sunil C; Goswami, Chandan

    2016-03-01

    The morphology, ultrastructure, and functions of mature avian spermatozoa have been of immense commercial and scientific interest for several reasons. This is mainly important in case of birds in poultry production, conservation, and in the use of sperm morphometry as phylogenetic evidence. Avian spermatozoa share complex or no correlation of sperm morphometry with respect to testis and/or body size as described before. In this work, we have isolated mature spermatozoa from White Pekin duck (Anas platyrhynchos) by non-invasive methods and performed several immunostaining analysis as well as cytochemical analysis using electron and light microscopes. Here, we report the presence of different post-translationally modified tubulin such as tyrosinated-, detyrosinated-, acetylated-, polyglutamylated-, and glycylated-tubulin in specific regions of the mature spermatozoa. By using field-emission scanning electron microscope, we confirm the presence of acrosome-like structure at the tip of the sperm head. However, this structure remains non-reactive to common lectins such as Peanut Agglutinin (PNA) and cholesterol-sensitive dyes such as Filipin. We report that this acrosomal structure is primarily made of lipid-based structures and is resistant to 0.1% Triton X100. Confocal microscopy and super resolution structured illumination microscopy study indicates that the nucleus is bifurcated at the tip region. By using specific markers, we report that the perforatorium structure present at the tip of the spermatozoa head contains specialized organelles that is similar to atypical mitochondria. We propose that these ultrastructural and molecular parameters can be used as species-specific features. The bifurcated nucleus and presence of atypical mitochondria within this structure may be relevant for the complex mitochondrial inheritance and mitochondrial heteroplasmy observed in case of avian population. PMID:26824840

  8. 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.

  9. Light and electron microscopic study of autologous implants of dental roots in the subcutaneous tissue of rats.

    PubMed

    Cerri, P S; Freymüller, E; Katchburian, E

    1997-05-01

    Maxillary first molars of rats were extracted. The roots were separated and subsequently implanted in the dorsal subcutaneous tissue of the same animal. In Experiment 1, the roots were implanted immediately after removal; in Experiment 2, the roots were subjected to freeze-thawing (devitalized) before implantation. After 4, 8, and 15 weeks of implantation, the roots were removed and processed for light and transmission electron microscopy. Roots of Experiment 1 showed an amorphous clear material filling depressions on the irregular surface of the cementum. This material consisted predominantly of collagen fibrils. Cells adjacent to the amorphous clear material exhibited numerous cytoplasmic processes surrounded by collagen fibrils. Globular structures with an electron-opacity similar to that of neighbouring cementum were observed within the bundles of collagen fibrils. Multinucleated cells with features of osteo/odontoclasts were often closely apposed to deep depressions of the cementum. In Experiment 2, only large multinucleated giant cells appeared around the surfaces of the roots. It seems therefore that, in Experiment 1, precementum formation and osteo/odontoclast mediated destruction occurred. It is likely that these activities may have originated from periodontal ligament cells carried to the implantation site. This conclusion is supported by the observation that such activities were absent in Experiment 2. Devitalized roots were unable to form precementum and were surrounded by foreign body giant cells. PMID:9566128

  10. Flexible high-voltage supply for experimental electron microscope

    NASA Technical Reports Server (NTRS)

    Chapman, G. L.; Jung, E. A.; Lewis, R. N.; Van Loon, L. S.; Welter, L. M.

    1969-01-01

    Scanning microscope uses a field-emission tip for the electron source, an electron gun that simultaneously accelerates and focuses electrons from the source, and one auxiliary lens to produce a final probe size at the specimen on the order of angstroms.

  11. 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.

  12. Quantitative in situ nanoindentation in an electron microscope

    SciTech Connect

    Minor, A. M.; Morris, J. W.; Stach, E. A.

    2001-09-10

    We report the development of a method for quantitative, in situ nanoindentation in an electron microscope and its application to study the onset of deformation during the nanoindentation of aluminum films. The force--displacement curve developed shows the characteristic ''staircase'' instability at the onset of plastic deformation. This instability corresponds to the first appearance of dislocations in a previously defect-free grain. Plastic deformation proceeds through the formation and propagation of prismatic loops punched into the material, and half loops that emanate from the sample surface. These results represent the first real time observations of the discrete microstructural events that occur during nanoindentation.

  13. Adaptive noise Wiener filter for scanning electron microscope imaging system.

    PubMed

    Sim, K S; Teh, V; Nia, M E

    2016-01-01

    Noise on scanning electron microscope (SEM) images is studied. Gaussian noise is the most common type of noise in SEM image. We developed a new noise reduction filter based on the Wiener filter. We compared the performance of this new filter namely adaptive noise Wiener (ANW) filter, with four common existing filters as well as average filter, median filter, Gaussian smoothing filter and the Wiener filter. Based on the experiments results the proposed new filter has better performance on different noise variance comparing to the other existing noise removal filters in the experiments. PMID:26235517

  14. Role of intestinal mucus in crystal biogenesis: an electron-microscopical, diffraction and X-ray microanalytical study.

    PubMed

    Humbert, W; Voegel, J C; Kirsch, R; Simonneaux, V

    1989-03-01

    In the posterior intestine of the sea-water eel, mucus plays an important role in biocrystallization of calcium ions. By means of transmission and scanning electron microscopy associated with X-ray microanalysis and X-ray diffraction it has been possible to determine the role of mucous fibers as nucleation sites. Biocrystallization occurs in 2 steps: (1) Calcification of mucus. As soon as mucus is excreted in the intestinal lumen, it is loaded with calcium, as shown by lanthanum affinity and X-ray microanalysis on freeze-dried tissues. (2) Genesis of crystals. Needle-shaped crystallites build up in coalescent spherites in the intestinal lumen near the microvilli. Genesis occurs as follows: (a) crystallite mineralization by nucleation in an organic matrix composed of glycoproteinaceous mucous fibers, followed by the appearance of spherites; (b) coalescence in spherites and association of spherites in rhombohedra; (c) extrusion of organic material during the final step of crystallization. PMID:2706658

  15. 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.

  16. 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. PMID:26104134

  17. 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

  18. ELECTRON MICROSCOPE STUDIES ON SOMA-SOMATIC INTERNEURONAL JUNCTIONS IN THE CORPUS PEDUNCULATUM OF THE WOOD ANT (FORMICA LUGUBRIS ZETT.)

    PubMed Central

    Landolt, Alex M.; Ris, Hans

    1966-01-01

    1. The corpora pedunculata of the wood ant (Formica lugubris Zett.) contain densely packed neuron perikarya which are separated by ultrathin glial sheaths. 2. These glial sheaths are occasionally interrupted by round holes with an average surface area of 2.64 µ2. The holes are designated glial windows since they represent intracellular gaps of glial cytoplasm. 3. The glial windows allow soma-somatic interneuronal junctions. Of all adjacent neurons in a selected neuron pool, only 42% were interconnected by such junctions. 4. The intercellular space at the soma-somatic junctions has an average diameter of 30 A; occasionally, it is collapsed and an external compound membrane ensues. The junctional membranes are characterized by the presence of a subunit pattern of cross-directional electron-opaque lines with a 50- to 70-A periodicity. 5. Morphological signs of chemical transmission are absent in these junctions. On the other hand, there is a striking similarity in structural organization between soma-somatic junctions and electrical synapses described in other species. Therefore, it is suggested that these cell contacts of the ant's "cerebral cortex" are another form of electrical junction. 6. The close proximity of the junctions to the cell nucleus is noted. Its significance could not be ascertained. 7. The suggestion is made that glial windows may have dynamic properties and may intervene in the regulation of interneuronal transfer of information. PMID:5914698

  19. Effects of 8-methoxypsoralen plus 365 nm UVA light on Candida albicans cells. An electron microscopic study.

    PubMed

    Scherwitz, C; Rassner, G; Martin, R

    1978-09-28

    Candida (C) albicans cells were exposed to 8-Methoxypsoralen (8-MOP) concentrations of 1.0 microgram/ml and 10.0 microgram/ml medium and irradiated with 365 nm light. The amount of energy emitted was 4.8 J/cm2. Two divergent types of cell damage occured concerning yeast cell cytoplasm and cell wall. Two hours after exposure cytoplasmic changes involving mitochondria, which showed irregularities in shape, blurred appearance or loss of mitochondrial cristae and outer membrane were seen. The number of vacuoles was increased. The cytoplasm showed large electron transparent areas, the cytoplasmic membrane disappeared in some areas completely. Nucleus and nuclear envelope usually remained intact in early stages. 24h after exposure conspicuous cell wall alterations were observed in addition to cytoplasmic changes. Newly produced cell wall material formed ball-like protrusions or was adherent sickle-shaped to the cell wall. The investigations strongly suggest that the results found after 8-MOP-UVA treatment of C. albicans cells can not be interpreted in the sense of a general cytotoxic effect. Apparently it takes the form of a combination of events involving regressive and progressive alterations. PMID:363068

  20. Effects of 8-methoxypsoralen plus 365 nm UVA light on Candida albicans cells. An electron microscopic study.

    PubMed

    Scherwitz, C; Rassner, G; Martin, R

    1978-01-01

    Candida (C.) albicans cells were exposed to 8-Methoxypsoralen (8-MOP) concentrations of 1.0 microgram/ml and 10.0 micrograms/ml medium and irradiated with 365 nm light. The amount of energy emitted was 4.8 J/cm2. Two divergent types of cell damage occured concerning yeast cell cytoplasm and cell wall. Two hours after exposure cytoplasmic changes involving mitochondria, which showed irregularities in shape, blurred appearance or loss of mitochondrial cristae and outer membrane were seen. The number of vacuoles was increased. The cytoplasm showed large electron transparent areas, the cytoplasmic membrane disappeared in some areas completely. Nucleus and nuclear envelope usually remained intact in early stages. 24 h after exposure conspicuous cell wall alterations were observed in addition to cytoplasmic changes. Newly produced cell wall material formed ball-like protrusions or was adherent sickle-shaped to the cell wall. The investigations strongly suggest that the results found after 8-MOP-UVA treatment of C. albicans cells can not be interpreted in the sense of a general cytotoxic effect. Apparently it takes the form of a combination of events involving regressive and progressive alterations. PMID:394689

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

    SciTech Connect

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

    1982-09-01

    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 H/sub II/ configuration. The H/sub II/ 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 angstrom unit cell is observed (at near total dehydration) to a resolution of 6 angstrom. 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, necessity of avoiding phase separations may provide a rationale for the peculiar morphology of the ROS.

  2. 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.

  3. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    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.

  5. 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.

  6. 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.

  7. 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

  8. 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. PMID:24373492

  9. 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)

  10. An Electron-microscope Study of the Response of Mesothelial Cells to the Intrapleural Injection of Asbestos Dust

    PubMed Central

    Davis, J. M. G.

    1974-01-01

    Studies of the pleural mesothelium in rats, mice, and guinea-pigs following the intrapleural injection of asbestos dust, showed that for 6 months at least this dust did not induce mesothelial hyperplasia. During the first few days after injection some areas of mesothelial cells became rounded and less clearly attached to one another, and a few were found to contain small numbers of asbestos fibres. During this period there was evidence of the penetration of asbestos fibres between the mesothelial cells, into the submesothelial connective tissues. Later in the studies the mesothelium covering most of the pleural cavity returned to normal, but where mesothelium covered asbestos granulomata, the cells were found to be extremely flattened, and without surface microvilli. Usually the mesothelial covering was complete, but in some areas pores were found penetrating the mesothelial cell cytoplasm and leaving areas of connective tissue in direct contact with the pleural cavity. In a few cases mesothelial cells were found lining clefts within the connective tissue of asbestos granulomata. ImagesFigs. 5-7Figs. 1-2Figs. 3-4 PMID:4835798

  11. Immunohistochemical and electron microscopic study of interaction of Yersinia enterocolitica serotype O8 with intestinal mucosa during experimental enteritis.

    PubMed Central

    Hanski, C; Kutschka, U; Schmoranzer, H P; Naumann, M; Stallmach, A; Hahn, H; Menge, H; Riecken, E O

    1989-01-01

    The experimental infection of mice with Yersinia enterocolitica serotype O8 was investigated in a quantitative and histological study. The course of bacterial penetration and spreading was precisely determined by immunohistochemical staining. After oral administration, the bacteria passed the epithelial barrier of the ileum and spread into the lamina propria. By preference they entered Peyer's patches, which were about 1,000 times more heavily colonized than the surrounding epithelium of a comparable surface area. The bacteria proliferated in the follicles, from which they spread into the lamina propria of the villi. At either site most of the bacteria multiplied extracellularly, with only a small percentage observed to be present within the phagocytes. The bacteria did not appear to be able to pass the intact basement membrane; hence, the integrity of the basement membrane is likely to play a role in determining the route of entry and limit of spread of Y. enterocolitica infection. Images PMID:2917779

  12. 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

  13. Light and transmission electron microscopic studies of a haemogregarine in naturally infected fan-footed gecko (Ptyodactylus hasselquistii).

    PubMed

    Hussein, Abdel-Nasser A

    2006-04-01

    The present study focuses on and describes the developmental stages of a haemogregarine species in the blood and tissues of the gecko Ptyodactylus hasselquistii. The blood stages were differentiated into two forms: a short gamont measuring 11.87 x 6.42 microm and a banana-shaped mature gamont measuring 14.13 x 10.03 microm in length and width, respectively. Both erythrocytes and leucocytes had been invaded. The parasitaemia level is up to 410 per 10,000 erythrocytes counted. The gamont has a karyolytic effect on the host cell nucleus. Merogony occurred in the parenchyma cells of liver and the endothelial cells of the lung. The meronts in the lung were found in two forms: the micromeront measured 14.93x13.14 microm and produced a few numbers (average 4) of macromerozoites. The macromeront measured 26.3 x 16 microm and produced more small-sized merozoites (average 11.5), or micromerozoites. On the ultrastructural level, merozoites have a pellicle, which consists of an outer and inner membrane. The merozoites are nearly identical to the blood stages of the parasite. PMID:16416117

  14. [Comparative electron microscope studies on the kinetoplast morphology of bat-trypanosomes and Trypanosoma cruzi (author's transl)].

    PubMed

    Mühlpfordt, H

    1981-01-01

    Comparative studies on the ultrastructural morphology of kinetoplasts of trypanosomes belonging to the subgenus Schizotrypanum have been made. Three isolates of Trypanosoma vespertilionis and two strains of Trypanosoma dionisii derived from European bats were tested. Comparison was made also with two isolates from Brasilian bats characterized as T. cruzi and two strains which were derived from two patients suffering from Chagas' disease. In the epimastigote culture form of T. cruzi a typical configuration of kDNA becomes obvious, appearing as a central band at the beginning of cell division. It was investigated whether this morphological character can be used in differentiating between bat-trypanosomes and T. cruzi and on the species characterization of bat-trypanosomes. The central band of kDNA could be demonstrated in all cases of the trypanosomes examined. The special configuration of kDNA makes it possible to distinguish exactly between trypanosomes of the subgenus Schizotrypanum and other trypanosomes. Nevertheless this pecularity alone is not sufficient for characterizing species of that subgenus. PMID:7018104

  15. Retardation of peripheral nerve myelination in mice treated with inhibitors of cholesterol biosynthesis. A quantitative electron microscopic study.

    PubMed

    Rawlins, F A; Uzman, B G

    1970-09-01

    The effect of two inhibitors of cholesterol biosynthesis, triparanol and AY 9944, on peripheral nerve myelination, was studied. Suckling mice were intraperitoneally injected with both drugs on 3 consecutive days and were sacrificed 6 hr after the last injection; others were suckled by an injected mother and sacrificed at 2(1/2) days of age. A single mouse which had been injected with both drugs at 1, 2, and 3 days of age was sacrificed 2 wk after the last injection. Membranous and crystalline intracytoplasmic inclusions were observed in the Schwann cells of the sciatic nerves of all the experimental animals. Both the number of unmyelinated single axons and the number of myelin lamellae around each myelinating axon in the sciatic nerves were recorded for treated mice and of mice suckled by treated mothers. The sciatic nerve of the experimental mice contained a larger proportion of unmyelinated single axons and smaller numbers of myelin lamellae around the myelinating axons, when compared with age-matched controls. The results suggest that a decrease of endogenous cholesterol in suckling mice may affect peripheral nerve myelination in two ways: by retarding the "triggering" of myelination in unmyelinated axons and by decreasing the rate of myelination already in progress. PMID:4349129

  16. Light and electron microscopic studies on the pigmented epithelium and photoreceptors of the retina of common buzzard (Buteo buteo).

    PubMed

    El-Beltagy, Abd El-Fattah B M

    2015-02-01

    The current study is essentially carried out to reveal the histological and ultra-structural details of the retinal pigmented epithelium (RPE) and photoreceptors cell layers of a common buzzard (Buteo buteo). The recorded results revealed that the neural retina of common buzzard consisted of seven distinct cell layers. The inner nuclear layer was markedly revealed as the thickest one among these layers. A highly melanized RPE was recorded in between the choroid and neural retina. Histologically, the RPE was represented by a single layer of cuboidal epithelial cells with centrally located nucleus. Ultrastructurally, the RPE cells showed numerous melanosomes, mitochondria, phagosomes, myeloid bodies, smooth endoplasmic reticulum (SER), but very rare rough endoplasmic reticulum (RER). The photoreceptor cell layer was represented by three categories of photoreceptor cells: few single rods, numerous single and double cones. Each double cone consisted of a short accessory cone and a long principle cone. The photoreceptor outer segment consisted of bi-membranous discs that are enclosed by outer membrane. Moreover, the inner segment of rods consisted of an ellipsoid and an inner hyperboloid. The hyperboloid was rich with RER, polysomes, Golgi apparatus and autophagic vacuoles. Furthermore, the inner segment of single cone and accessory cone consisted of an ellipsoid, paraboloid and myoid regions, while, the inner segment of principle cone lacked the paraboloid regions. At the proximal end of each inner segment for all types of cones, there was a large heterogeneous oil droplet. The paraboloid region was markedly rich with glycogen granules. The myoid region exhibited the same organelles but with little glycogen granules when compared with hyperboloid. PMID:25541273

  17. 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.

  18. 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).

  19. 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.

  20. Freeze-fracture electron microscopic and osmotic water permeability studies of epidermal lipid liposomes derived from stratum corneum lipids of porcine epidermis.

    PubMed

    Mandal, T K; Downing, D T

    1993-02-01

    Freeze-fracture electron microscopic studies revealed that the liposomal membrane morphology was intact before and after osmotic treatment. This finding suggested that water leakage from the liposomes was not due to fusion of two or more lipid vesicles, but rather to the osmotic salt effect. A stop-flow spectrophotometric study revealed that epidermal lipid liposomes derived from stratum corneum lipids of porcine skin underwent increases of the absorbances with decreases of volume of the vesicles. The initial rate at which the changes in optical density occurs is a measure of the water permeability through the liposomes. The reciprocal of the changes in the absorbance at the equilibrium at different salt osmotic shocks showed a linear dependence on the reciprocal of the osmotic pressure gradient, indicating that epidermal lipid liposomes are an ideal osmometer. The present investigation reports that lignoceric acid is a potent water barrier. Present findings suggest that the initial rate of water penetration decreased in the liposomes made from 30-45% (wt% ratio) of cholesterol and ceramides. Oleic acid as drug penetration enhancer facilitated the water diffusion of the stratum corneum lipid liposomes by a fluidizing effect on the liposomal membranes. Furthermore, ceramides are important in the water barrier properties of the skin. The permeability of water depends upon the amount (wt%) and the type of lipid of the membrane. PMID:8095743

  1. Enamel Surface Evaluation after Removal of Orthodontic Composite Remnants by Intraoral Sandblasting Technique and Carbide Bur Technique: A Three-Dimensional Surface Profilometry and Scanning Electron Microscopic Study

    PubMed Central

    Mhatre, Amol C; Tandur, Arundhati P; Reddy, Sumitra S; Karunakara, B C; Baswaraj, H

    2015-01-01

    Background: The purpose of this thesis is to present a practical and efficient clinical method of returning enamel to as near its original condition as possible following removal of bonded orthodontic attachments. The main objective of this study is to evaluate and compare the iatrogenic enamel damage caused by use of two different remnant removal techniques – sandblasting technique and carbide bur technique. Materials and Methods: 40 extracted premolar teeth were selected as sample. Premolar brackets were bonded on these teeth with two different types of light cure adhesive composite resin. The remnants present on these samples after debonding the brackets were removed with two different types of remnant removal techniques namely – Carbide bur technique and sandblasting technique. Then these treated surfaces were studied under Scanning electron microscope and three-dimensional profilometer for the damage caused to the enamel. Statistical analysis used Student’s t-tests. Results: The enamel surface structure after remnant removal with intraoral sandblasting is better than that after removal with a low-speed handpiece using tungsten carbide bur. Conclusion: Sandblasting can be an acceptable alternative to rotatory handpieces to restore the enamel surface to its near-original state and prevent permanent damage to the tooth. PMID:26668478

  2. Effect of residual chips on the material removal process of the bulk metallic glass studied by in situ scratch testing inside the scanning electron microscope

    SciTech Connect

    Huang Hu; Zhao Hongwei; Shi Chengli; Wu Boda; Fan Zunqiang; Wan Shunguang; Geng Chunyang

    2012-12-15

    Research on material removal mechanism is meaningful for precision and ultra-precision manufacturing. In this paper, a novel scratch device was proposed by integrating the parasitic motion principle linear actuator. The device has a compact structure and it can be installed on the stage of the scanning electron microscope (SEM) to carry out in situ scratch testing. Effect of residual chips on the material removal process of the bulk metallic glass (BMG) was studied by in situ scratch testing inside the SEM. The whole removal process of the BMG during the scratch was captured in real time. Formation and growth of lamellar chips on the rake face of the Cube-Corner indenter were observed dynamically. Experimental results indicate that when lots of chips are accumulated on the rake face of the indenter and obstruct forward flow of materials, materials will flow laterally and downward to find new location and direction for formation of new chips. Due to similar material removal processes, in situ scratch testing is potential to be a powerful research tool for studying material removal mechanism of single point diamond turning, single grit grinding, mechanical polishing and grating fabrication.

  3. 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

  4. 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.

  5. 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

  6. 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

  7. Comparative Evaluation of a New Endodontic Irrigant - Mixture of a Tetracycline Isomer, an Acid, and a Detergent to Remove the Intracanal Smear Layer: A Scanning Electron Microscopic Study

    PubMed Central

    Gupta, Poonam K; Mahajan, Uma Patil; Gupta, Kapil; Sheela, N V

    2015-01-01

    Background: The most important and demanding aspect of endodontic therapy is considered to be cleaning and shaping. Irrigation is considered a vital adjunct to instrumentation of the root canal for canal debridement. Until date, there is no single solution that simultaneously removes the smear layer and disinfects the entire root canal system. Thus, this in vitro study was designed to evaluate the efficiency of a new irrigation solution mixture of a tetracycline isomer, an acid, and a detergent (MTAD) (BioPure, Dentsply) containing a mixture of tetracycline (doxycycline hydrochloride), an acid (citric acid) and a detergent (Tween 80) in comparison with normal saline, 5% NaOCl and 17% ethylenediaminetetraacetic acid (EDTA) to remove intracanal smear layer. Materials and Methods: A total of 60 single rooted teeth were irrigated with Saline (Group A), 5% NaOCl (Group B), 17% EDTA (Group C) and MTDA (Group D). The extent of removal of smear layer and erosion was assessed using scanning electron microscope. Results: Irrigation with 5% NaOCl and MTAD as a final flush produced the cleanest surface with all the dentinal tubules open. No conjugation or erosion of dentinal tubules was noted (P > 0.05). Conclusion: MTAD flush was the most effective debridement regimen in all the three thirds of the canal showing its ability to reach the apex with no conjugation and erosion of dentinal tubules. PMID:25954062

  8. 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

  9. 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

  10. An in vitro evaluation of passive ultrasonic agitation of different irrigants on smear layer removal after post space preparation: a scanning electron microscopic study.

    PubMed

    Srirekha, A; Rashmi, K; Hegde, Jayshree; Lekha, S; Rupali, K; Reshmi, George

    2013-09-01

    This study evaluated the removal of debris and smear layer after post space preparation using different irrigations and passive ultrasonic agitation. Sixty human premolars were decoronated and post space prepared after endodontic therapy. The samples were then randomly divided into three experimental groups (Groups A, B, C) and one control group (Group D) with fifteen samples in each group. Groups A and B samples were treated with 10 % citric acid and 17 % ethylenediamintetraacetic acid (EDTA), respectively and passive ultrasonic agitation was done, rinsed with sodium hypochlorite and finally flushed with saline. Group C samples were conditioned with 36 % phosphoric acid and then rinsed with saline. The control group was treated with 3 % sodium hypochlorite, passive ultrasonic agitation done and flushed with saline. The samples were sectioned and evaluated for debris and smear layer removal under scanning electron microscope. 10 % citric acid showed the best removal of smear layer when compared with 17 % EDTA and 36 % phosphoric acid, but was not statistically significant (p > 0.05). The difference in scoring for debris and smear layer removal in the coronal, middle and apical third of post space of experimental groups in comparison with control group was statistically significant (p < 0.001). PMID:24431741

  11. Scanning electron microscope and dye penetration test: comparison of root canal preparation with 15 F CO2 laser microprobe versus conventional method--in vivo study

    NASA Astrophysics Data System (ADS)

    Kesler, Gavriel; Koren, Rumelia; Kesler, Anat; Hay, Nissim; Gal, Rivka

    1999-05-01

    The study was conducted on 30 vital maxillary or mandibulary teeth destined for extraction due to periodontal problems. 21 were experimentally treated with pulsed CO2 laser delivered by a newly developed fiber and 9 teeth represented the control group. The micro probe is a flexible, hollow, metal fiber, 300 μm in diameter and 20 mm in length, coupled onto a handpiece, with the following radiation parameters: wavelength-10.6μm pulse duration-50m.sec; energy per pulses 0.25 joule; energy density-360 J/cm2 per pulse; power on tissue-5W. The laser group was divided into three, receiving 20, 40 or 60 pulses, respectively. On light microscopy: in all the control group cases, large amount of residual pulp tissue was seen, it was diminished in some of the low energy group and was totally eradicated in the high energy group. This was confirmed by the scanning electron microscope (SEM) examination. The dentin tubuli were partly occluded with the low energy levels and completely with the high levels, as shown by the high-speed centrifuge dye penetration test and by the SEM tests.

  12. Effect of different final irrigating solutions on smear layer removal in apical third of root canal: A scanning electron microscope study

    PubMed Central

    Vemuri, Sayesh; Kolanu, Sreeha Kaluva; Varri, Sujana; Pabbati, Ravi Kumar; Penumaka, Ramesh; Bolla, Nagesh

    2016-01-01

    Aim: The aim of this in vitro study is to compare the smear layer removal efficacy of different irrigating solutions at the apical third of the root canal. Materials and Methods: Forty human single-rooted mandibular premolar teeth were taken and decoronated to standardize the canal length to 14 mm. They were prepared by ProTaper rotary system to an apical preparation of file size F3. Prepared teeth were randomly divided into four groups (n = 10); saline (Group 1; negative control), ethylenediaminetetraacetic acid (Group 2), BioPure MTAD (Group 3), and QMix 2 in 1 (Group 4). After final irrigation with tested irrigants, the teeth were split into two halves longitudinally and observed under a scanning electron microscope (SEM) for the removal of smear layer. The SEM images were then analyzed for the amount of smear layer present using a three score system. Statistical Analysis: Data are analyzed using the Kruskal-Wallis test and Mann-Whitney U-test. Results: Intergroup comparison of groups showed statistically significant difference in the smear layer removal efficacy of irrigants tested. QMix 2 in 1 is most effective in removal of smear layer when compared to other tested irrigants. Conclusion: QMix 2 in 1 is the most effective final irrigating solution for smear layer removal. PMID:26957801

  13. Development of scanning electron and x-ray microscope

    NASA Astrophysics Data System (ADS)

    Matsumura, Tomokazu; Hirano, Tomohiko; Suyama, Motohiro

    2016-01-01

    We have developed a new type of microscope possessing a unique feature of observing both scanning electron and X-ray images under one unit. Unlike former X-ray microscopes using SEM [1, 2], this scanning electron and X-ray (SELX) microscope has a sample in vacuum, thus it enables one to observe a surface structure of a sample by SEM mode, to search the region of interest, and to observe an X-ray image which transmits the region. For the X-ray observation, we have been focusing on the soft X-ray region from 280 eV to 3 keV to observe some bio samples and soft materials. The resolutions of SEM and X-ray modes are 50 nm and 100 nm, respectively, at the electron energy of 7 keV.

  14. 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.

  15. Electron sputtering in the analytical electron microscope: Calculations and experimental data

    SciTech Connect

    Zaluzec, N.J.; Mansfield, J.F.

    1987-03-01

    The environment of the electron microscope is particularly severe when one considers the energy deposited in a specimen during typical experimental conditions. Conventional imaging experiments tend to employ electron current densities ranging from approx.0.1 to 1 A/cm/sup 2/ while during microanalysis conditions probe current densities can range from 10 to values as high as 10/sup 5/ A/cm/sup 2/. At 100 kV this corresponds to power densities from 100 Kilowatts/cm/sup 2/ to 10/sup 4/ Megawatts/cm/sup 2/. These energy deposition rates can result in electron irradiation damage which can substantially alter the structure and composition of a specimen through either ionization damage in organics or by displacement damage in inorganics and/or combinations thereof. For the most part materials scientists operating an analytical electron microscope (AEM) in the 100 to 200 kV regime studying metallic and/or ceramic specimens have been spared the need to consider either of these effects as their specimens have tended to be sufficiently resilient. However, the advent of the new medium voltage microscopes operating in the 300 to 400 kV regime with high brightness guns and clean or ultrahigh vacuum systems has necessitated a reevaluation of the effects of higher voltage operation in light of the destructive nature of the electron beam particularly under microanalysis conditions.

  16. 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.

  17. 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

  18. Scanning electron microscopic observations of Anopheles albimanus (Diptera: Culicidae) eggs.

    PubMed

    Rodriguez, M H; Chavez, B; Orozco, A; Loyola, E G; Martinez-Palomo, A

    1992-05-01

    To investigate the existence of subspecies of Anopheles albimanus Wiedeman in southern Mexico, the egg morphology of specimens obtained from several field populations and from insectary-adapted colonies of uniform pupal phenotype was examined. Scanning electron microscopic observations have shown that the eggs of An. albimanus are polymorphic in respect to the size and shape of their floats, but not in their ornamentation. Four types of eggs were found. Differences in the proportion of the various morphological types were statistically significant, although proportions of egg types were variable among individuals within the same population. These observations are suggestive of distinctive populations and warrant further studies using more sensitive methods to investigate sibling species in An. albimanus sensu lato. PMID:1625289

  19. Observation of the freeze-drying process of biological materials with a scanning electron microscope.

    PubMed

    Nei, T; Fujikawa, S

    1976-10-01

    Over the past few decades, numerous studies have been done on the freeze-drying of biological materials from a physical, chemical and biological point of view. Morphological observation of the freeze-drying process of specimens, however, has been tried by only a few investigators. In those studies, thin-layered aqueous specimens, which were sandwiched between two cover slips, were mostly observed with an optical microscope. For ultrastructural and stereoscopic observation, the scanning electron microscope has a great advantage, unlike that of the optical microscope. A specially designed cryo-scanning electron microscope, employed in the present study, made it possible to observe the freezing patterns of the specimens and also the sublimation process of ice in frozen specimens under vacuum. With this specially designed microscope, shrinkage of some specimens due to dehydration during the freeze-drying process was revealed and the extent of such shrinkage was quantitatively determined. PMID:1036327

  20. 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

  1. Improved coating and fixation methods for scanning electron microscope autoradiography.

    PubMed

    Weiss, R L

    1984-01-01

    A simple apparatus for emulsion coating is described. The apparatus is inexpensive and easily assembled in a standard glass shop. Emulsion coating for scanning electron microscope autoradiography with this apparatus consistently yields uniform layers. When used in conjunction with newly described fixation methods, this new approach produces reliable autoradiographs of undamaged specimens. PMID:6234956

  2. 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.

  3. Scanning electron microscope for in situ study of crystallization of Ge2Sb2Te5 in phase-change memory.

    PubMed

    Yin, You; Niida, Daisuke; Ota, Kazuhiro; Sone, Hayato; Hosaka, Sumio

    2007-12-01

    By introducing electrical connections into the chamber of a scanning electron microscope (SEM) via its holder assembly, it has become feasible to in situ observe and electrically characterize electronic devices. The in situ SEM was applied to investigate electric-pulse-induced behavior of Ge(2)Sb(2)Te(5) in a lateral phase-change memory cell. Randomly distributed nuclei with sizes from 20 to 80 nm were initiated at a low voltage pulse. Initially, grain growth depended strongly on pulse amplitude at around 60.3 nm/V and then a weak pulse amplitude dependence was observed at around 13.5 nm/V. Device resistance during crystallization dropped by two to three orders of magnitude with two falling steps, which probably resulted from amorphous to face-centered-cubic and subsequently to hexagonal transitions, respectively. PMID:18163750

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. Direct demonstration of insulin receptor internalization. A quantitative electron microscopic study of covalently bound /sup 125/I-photoreactive insulin incubated with isolated hepatocytes

    SciTech Connect

    Gorden, P.; Carpentier, J.L.; Moule, M.L.; Yip, C.C.; Orci, L.

    1982-07-01

    When /sup 125/I-insulin is incubated with isolated rodent hepatocytes at 37 degrees C, the ligand initially binds to the plasma membrane of the cell and is subsequently internalized by adsorptive endocytosis. To confirm directly that the insulin receptor is internalized with the ligand, we covalently linked photoreactive /sup 125/I-N sigma B29 (azidobenzoyl) insulin to its specific hepatocyte receptor and followed its fate by quantitative electron microscopic autoradiography. We found that the covalently linked photoreactive insulin is internalized by the cell in fashion analogous to the internalization of ordinary /sup 125/I-insulin, indicating that, at least under these conditions, the insulin receptor is internalized with the ligand.

  12. 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.

  13. 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.

  14. Local dynamic range compensation for scanning electron microscope imaging system.

    PubMed

    Sim, K S; Huang, Y H

    2015-01-01

    This is the extended project by introducing the modified dynamic range histogram modification (MDRHM) and is presented in this paper. This technique is used to enhance the scanning electron microscope (SEM) imaging system. By comparing with the conventional histogram modification compensators, this technique utilizes histogram profiling by extending the dynamic range of each tile of an image to the limit of 0-255 range while retains its histogram shape. The proposed technique yields better image compensation compared to conventional methods. PMID:25969945

  15. In Situ Nanomechanical Testing of Crystalline Nanowires in Electron Microscopes

    NASA Astrophysics Data System (ADS)

    Zhu, Yong

    2016-01-01

    This article reviews in situ mechanical testing of crystalline nanowires in scanning and transmission electron microscopes, focusing on bottom-up synthesized, single-crystalline nanowires. Major experimental methods including resonance, bending, tension and buckling are summarized. In addition to commonly encountered experimental issues, deformation mechanisms learned from the in situ nanomechanical characterization are discussed highlighting the roles of free surfaces, internal planar defects and point defects.

  16. Design of an electron microscope phase plate using a focused continuous-wave laser

    SciTech Connect

    Spence, J.; Muller, H; Jin, Jian; Danev, R; Padmore, H; Glaeser, R.M

    2010-07-01

    We propose a Zernike phase contrast electron microscope that uses an intense laser focus to convert a phase image into a visible image. We present the relativistic quantum theory of the phase shift caused by the laser–electron interaction, study resonant cavities for enhancing the laser intensity and discuss applications in biology, soft-materials science and atomic and molecular physics.

  17. Design of an electron microscope phase plate using a focused continuous-wave laser

    PubMed Central

    Müller, H; Jin, Jian; Danev, R; Spence, J; Padmore, H; Glaeser, R M

    2010-01-01

    We propose a Zernike phase contrast electron microscope that uses an intense laser focus to convert a phase image into a visible image. We present the relativistic quantum theory of the phase shift caused by the laser–electron interaction, study resonant cavities for enhancing the laser intensity and discuss applications in biology, soft-materials science and atomic and molecular physics. PMID:20808709

  18. A fast iterative technique for restoring scanning electron microscope images

    NASA Astrophysics Data System (ADS)

    Nakahira, Kenji; Miyamoto, Atsushi; Honda, Toshifumi

    2014-12-01

    This paper proposes a fast new technique for restoring scanning electron microscope images to improve their sharpness. The images with our approach are sharpened by deconvolution with the point spread function modeled as the intensity distribution of the electron beam at the specimen's surface. We propose an iterative technique that employs a modified cost function based on the Richardson-Lucy method to achieve faster processing. The empirical results indicate significant improvements in image quality. The proposed approach speeds up deconvolution by about 10-50 times faster than that with the conventional Richardson-Lucy method.

  19. 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.

  20. Characterization of quantum well structures using a photocathode electron microscope

    NASA Technical Reports Server (NTRS)

    Spencer, Michael G.; Scott, Craig J.

    1989-01-01

    Present day integrated circuits pose a challenge to conventional electronic and mechanical test methods. Feature sizes in the submicron and nanometric regime require radical approaches in order to facilitate electrical contact to circuits and devices being tested. In addition, microwave operating frequencies require careful attention to distributed effects when considering the electrical signal paths within and external to the device under test. An alternative testing approach which combines the best of electrical and optical time domain testing is presented, namely photocathode electron microscope quantitative voltage contrast (PEMQVC).

  1. Simulation of transmission electron microscope images of biological specimens.

    PubMed

    Rullgård, H; Ofverstedt, L-G; Masich, S; Daneholt, B; Oktem, O

    2011-09-01

    We present a new approach to simulate electron cryo-microscope images of biological specimens. The framework for simulation consists of two parts; the first is a phantom generator that generates a model of a specimen suitable for simulation, the second is a transmission electron microscope simulator. The phantom generator calculates the scattering potential of an atomic structure in aqueous buffer and allows the user to define the distribution of molecules in the simulated image. The simulator includes a well defined electron-specimen interaction model based on the scalar Schrödinger equation, the contrast transfer function for optics, and a noise model that includes shot noise as well as detector noise including detector blurring. To enable optimal performance, the simulation framework also includes a calibration protocol for setting simulation parameters. To test the accuracy of the new framework for simulation, we compare simulated images to experimental images recorded of the Tobacco Mosaic Virus (TMV) in vitreous ice. The simulated and experimental images show good agreement with respect to contrast variations depending on dose and defocus. Furthermore, random fluctuations present in experimental and simulated images exhibit similar statistical properties. The simulator has been designed to provide a platform for development of new instrumentation and image processing procedures in single particle electron microscopy, two-dimensional crystallography and electron tomography with well documented protocols and an open source code into which new improvements and extensions are easily incorporated. PMID:21631500

  2. 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.

  3. 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.

  4. The Effect of Four Commonly used Root Canal Irrigants on the Removal of Smear Layer: An In-vitro Scanning Electron Microscope Study

    PubMed Central

    Kumar, Pawan; Prasad, Narayana; Darawade, Ashish; Bhagat, Shresht Kumar; Narayana, Narayana; Darawade, Pradyma

    2015-01-01

    Background: The objective of this study was to compare the efficiency of four commonly used chemicals in their ability to remove smear layer after instrumentation using scanning electron microscope (SEM). Materials and Methods: Seventy-five extracted single canaled teeth of roots ranging 10-12 mm in length were used for the study. Teeth were divided into 4 study groups and 1 control group of 15 teeth each. Standard access to the pulp chambers were performed with diamond burs. The lengths of the teeth were determined by the introduction of a size 15 K-file into the root canal until the tip reached the apical foramen. The working length for preparation of the canal is set 0.5 mm shorter than the measurement. Irrigation was performed using 2 ml of irrigant for every instrument change and finally rinsed using 5 ml of the respective solutions. The roots were then split with a chisel and hammer. One-half of each tooth was selected and prepared for SEM examination. After assembly on coded stubs, the specimens were placed in a vacuum chamber and sputter-coated with a 300 Å gold layer. The specimens were then analyzed using a Philips SEM XL 30. The dentinal wall of the cervical, middle and apical thirds was observed at magnifications of up to ×1000 for the presence/absence of smear layer and visualization of the entrance to dentinal tubules. Photomicrographs (×1000) of these areas on each of the coronal, middle and apical thirds were made Data were analyzed using Kruskal–Wallis test and Mann–Whitney U test. Results: SEM study done on these prepared teeth with the popularly used four chemicals, namely, 3% NaOCl (Group A), 3% NaOCl followed by 17% ethylene diamine-tetra-acetic acid (Group B), 0.2% chlorhexidine (Group C) and 3% NaOCl followed by MTAD (Group D), with distilled water (Group E) which is used as control, revealed that NaOCl showed statistically significant, better cleansing effect than distilled water. Chlorhexidine and NaOCl showed equal kind of efficacy

  5. 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.

  6. 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.

  7. 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).

  8. Brain pathology induced by infection with the human immunodeficiency virus (HIV). A histological, immunocytochemical, and electron microscopical study of 100 autopsy cases.

    PubMed

    Budka, H; Costanzi, G; Cristina, S; Lechi, A; Parravicini, C; Trabattoni, R; Vago, L

    1987-01-01

    Neuropathological examination of brain tissue of 100 patients with infection by the human immunodeficiency virus (HIV), including 98 with clinically manifest acquired immune deficiency syndrome (AIDS), revealed distinct multifocal-disseminated and diffuse brain tissue lesions, which can be regarded as HIV-induced brain lesions: multifocal giant cell encephalitis (MGCE; 4) and progressive diffuse leukoencephalopathy (PDL; 25). These lesions were found in 38 brains, and in 17 in absence of infectious, necrotizing or inflammatory changes of other types. In 13 brains, a combination of MGCE with PDL was seen, suggesting a spectrum of HIV-induced brain lesions. MGCE is characterized by perivascular accumulations predominantly of rod cells, monohistiocytes and macrophages, all of which are strongly labeled with a monoclonal antibody to macrophages. Most conspicuous are multinucleated giant cells which are also labeled by anti-macrophage antibody, and which can be regarded as evidence of the local presence of HIV, as confirmed by electron microscopical detection of HIV particles in four MGCE brains, and by immunocytochemical detection of HIV proteins in two MGCE brains. PDL is characterized by a triad: diffuse myelin loss, astroglial proliferation, and infiltration by mono- and multinucleated macrophages. HIV-induced lesions can be morphologically differentiated from histopathological brain lesions known in immunosuppression, including what is called here nodular encephalitis ["subacute encephalitis" of the literature, in most cases attributable to cytomegalovirus (CMV) or toxoplasmosis], by their characteristic histopathology including the hallmark presence of multinucleated giant cells, by direct immunocytochemical and electron microscopical demonstration of HIV in the lesions, and by the absence of opportunistic agents (bacteria, fungi, Toxoplasma, CMV, HSV or papovaviruses). Diffuse poliodystrophy (diffuse proliferation of astroglia with swollen nuclei, occasionally

  9. 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}.

  10. In situ laser processing in a scanning electron microscope

    SciTech Connect

    Roberts, Nicholas; Fowlkes, Jason Davidson; Rack, Prof. Philip; Moore, Tom; Magel, Greg; Hartfield, Cheryl

    2012-01-01

    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 {micro}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}.

  11. Scanning electron-microscopic studies on the three-dimensional structure of mitochondria in the mammalian red, white and intermediate muscle fibers.

    PubMed

    Ogata, T; Yamasaki, Y

    1985-01-01

    The three-dimensional structure and arrangement of mitochondria in the red, white and intermediate striated muscle fibers of the rat were examined under a field-emission type scanning electron microscope after removal of cytoplasmic matrices by means of the Osmium-DMSO-Osmium procedure. Beneath the sarcolemma, spherical or ovoid subsarcolemmal mitochondria show accumulations. The mitochondria are numerous and large in size in the red fibers, intermediate in the intermediate fibers, and few and small in the white fibers. Paired, slender I-band-limited mitochondria were located on both sides of the Z-line and partly embraced the myofibrils at the I-band level; they occurred in all three types of fibers. In the intermyofibrillar spaces, numerous mitochondria formed mitochondrial columns. These columns were classified into two types: 1) thick mitochondrial columns, formed by multiple mitochondria each with an intermyofibrillar space corresponding to one sarcomere in length, and 2) thin mitochondrial columns, established by single mitochondria corresponding to one sarcomere in length. In the red fibers mitochondrial columns were abundant and the ratio of the thick and thin columns was almost the same, while in the intermediate fibers most of the columns belonged to the thin type. The white fibers displayed rare, very thin columns. PMID:4028126

  12. Trim simulations and possible studies for edge-on ion irradiation of electron microscope specimens. [Co ions implanted into Si to form CoSi[sub 2

    SciTech Connect

    Thompson, L.J.; Allen, C.W. ); Frischherz, M.C. Atominstitut der Oesterreichischen Universitaeten, Vienna ); Otero, M.P. Fundacao de Tecnologia Industrial , Lorena, SP )

    1992-01-01

    A TRIM code has been modified to simulate a special technique, first described at the Spring 92 MRS Meeting, for in-situ transmission electron microscope (TEM) experiments involving simultaneous ion irradiation, in which the resultant phenomena are observed as in a cross-section TEM specimen without further specimen preparation. Instead of ion-irradiating the film or foil specimen normal to the major surfaces and observing in plan view (i.e., in essentially the same direction), the specimen is irradiated edge-on (i.e., parallel to the major surfaces) and is observed normal to the depth direction of the irradiation. Results of calculations utilizing the modified TRIM code are presented for cases of 200 and 500 keV Co impinging onto the edge of Si films 200 and 600 nm thick. Limitations of the technique are discussed and feasibility of experiments involving implantation of Co into Si and the formation of CoSi[sub 2], which employ this technique, are briefly discussed. 10 refs, 3 figs.

  13. 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

  14. 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.

  15. Transmission electron microscope evidence of telocytes in canine dura mater.

    PubMed

    Xu, Ting; Lu, Shanshan; Zhang, Hongqi

    2016-01-01

    Telocytes (TCs) are a novel type of interstitial cells present in a wide variety of organs and tissues (www.telocytes.com). Telocytes are identified morphologically by a small cell body and specific long prolongations (telopodes) alternating thin segments (podomers) with dilations (podoms). The presence of TCs in rat meninges has been identified in previous research. We here present further evidence that TCs existed in canine dura mater, closed to capillary and surrounded by a great deal of collagen fibres under transmission electron microscope. PMID:26781033

  16. 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.

  17. New methods for cathodoluminescence in the scanning electron microscope.

    PubMed

    Boyde, A; Reid, S A

    1983-01-01

    Experiments using the CL imaging mode to recognise osteoid in the polished, cut surfaces of bone biopsies embedded in PMMA led to the development of a number of new methods for contrast formation in CL images in the SEM. These involve: (1) enhancing or (2) reducing the CL signal by staining the specimen, (3) utilising the cathodoluminescence of glass microscope slides to produce images of histological sections mounted on glass so that features in the section which scatter the electron beam appear dark against a light background, and (4) enhancing the CL signal from PMMA so that features which are less penetrated by the scintillator show up dark against a bright background. Efforts to increase the efficiency of light collection resulted in the development of a new means for manufacturing reflector-cum-light guide CL detectors by wrapping aluminum foil around a wooden former. These detectors enshroud the specimen so that CL light can only escape to the photomultiplier window (or back up the final lens). A variety of such designs have proved more efficient than the conventional plastic light guides used as CL detectors. By enlarging the beam entry aperture, other SE and BSE detectors can be used simultaneously. Examples of the value of the CL mode in mineralised tissue research include the use of enhanced CL plastic embedding media to detect marrow space and of enhanced osteoid CL to detect unmineralised bone matrix; the use of tetracycline as a growth marker in pathological studies of bone and experimental studies with bone, dentine and enamel; the use of bisbenzamid to locate and count nuclei in osteoclasts, the hard tissue resorbtive cells; and the use of superficial stain absorption of auto-CL to locate stained material on tooth surfaces, with the view to monitor the efficiency of periodontal therapy. PMID:6669948

  18. Microscopic ESR study of N@C60 using a Magnetic Resonance Force Microscope

    NASA Astrophysics Data System (ADS)

    Banerjee, P.; Pelekhov, D. V.; Fong, K. C.; Lee, I. H.; Hammel, P. C.; Harneit, W.

    2007-03-01

    We report electron spin resonance studies of the endohedral fullerene N@C60 using the novel technique of magnetic resonance force microscopy (MRFM). These studies are performed at temperatures down to 1 K on both thin films of N@C60 and in samples where the endohedral fullerene is incorporated into a bulk crystalline matrix. Utilizing the large magnetic field gradients (˜ 10^5 Tesla/meter) in the vicinity of our micromagnetic probe tip, we are able to selectively probe the electron spins in sub--micron volumes. Further, our schemes for spin manipulation allow us to measure the spin--lattice relaxation rate (T1-1) with a spatial resolution in one dimension of approximately 20 nanometers. We will also discuss our efforts to improve the sensitivity of our microscope for detecting individual electronic spins. B. Naydenov, C. Spudat, W. Harneit, H. I. Suss, J. Hullinger, J. Nuss, M. Jansen, Chem. Phys. Lett., 424, 327 (2006).

  19. Ultrahigh vacuum scanning electron microscope system combined with wide-movable scanning tunneling microscope

    SciTech Connect

    Kaneko, A.; Homma, Y.; Hibino, H.; Ogino, T.

    2005-08-15

    A surface analysis system has been newly developed with combination of ultrahigh vacuum scanning electron microscope (SEM) and wide-movable scanning tunneling microscope (STM). The basic performance is experimentally demonstrated. These SEM and STM images are clear enough to obtain details of surface structures. The STM unit moves horizontally over several millimeters by sliding motion of PZT actuators. The motion resolution is proved to be submicrometers. The STM tip mounted on another PZT scanner can be guided to a specific object on the sample surface during SEM observation. In the observation of a Si(111) surface rapidly cooled from high temperature, the STM tip was accurately guided to an isolated atomic step and slightly moved along it during SEM observation. The STM observation shows an asymmetry of the (7x7)-transformed region along the step between the upper and lower terraces. (7x7) bands continuously formed along the edge of terraces, while (7x7) domains distributed on the terraces slightly far from the step. These experiments show the wide-movable STM unit resolves a gap of observation area between SEM and STM and the system enables a specific object found in the SEM image to be observed easily by STM.

  20. Probing electron transport and structural properties of nanostructures on Si with a quadraprobe scanning tunneling microscope

    SciTech Connect

    Kim, Tae Hwan; Wendelken, J F; Li, An-Ping

    2008-01-01

    The electron transport and structural properties of nanostructured materials have been examined with a newly developed low temperature quadraprobe scanning tunneling microscope (STM) system. The quadraprobe STM system, as a "nano" version of a four-probe station provides an integrated research platform with a low temperature four-probe STM, a molecular-beam epitaxy growth chamber, a high resolution scanning electron microscope, and a scanning Auger microscope. The four STM probes can be driven independently with sub-nanometer precision, enabling conventional STM imaging and four-point electrical transport study of surface electronic systems and nanostructured materials at temperatures down to 10 K. Self-assembled nanostructures grown on Si by doping with metal atoms (Au, Gd, Ag) have been fabricated and characterized in situ.

  1. Coherent Chromatic Effect in the Transmission Electron Microscope.

    PubMed

    Erni, Rolf

    2016-03-18

    Under the assumption of local atomic scattering, elastic electron scattering at finite scattering angles implies a small but finite energy loss. This energy loss, which under conventional imaging conditions in high-resolution transmission electron microscopy is of the order of 0.1 meV and thus negligible, increases by more than 2 orders of magnitude if light elements are investigated at sub-Ångström resolution. For a microscope of finite chromatic aberration, the energy loss leads to an element-specific chromatic effect which increases with the instrument resolution and with decreasing mass of the scattering atom. Despite that this effect is small, it can degrade the achievable image contrast. However, the effect can be considered in the optimization of the phase-contrast imaging conditions and even be beneficial to enhance the relative image contrast of light atoms in the presence of heavy atoms. PMID:27035311

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. Examination of Surveyor 3 parts with the scanning electron microscope and electron microprobe

    NASA Technical Reports Server (NTRS)

    Chodos, A. A.; Devaney, J. R.; Evens, K. C.

    1972-01-01

    Two screws and two washers, several small chips of tubing, and a fiber removed from a third screw were examined with the scanning electron microscope and the electron microprobe. The purpose of the examination was to determine the nature of the material on the surface of these samples and to search for the presence of meteoritic material.

  8. 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

  9. Damage-free vibrational spectroscopy of biological materials in the electron microscope

    NASA Astrophysics Data System (ADS)

    Rez, Peter; Aoki, Toshihiro; March, Katia; Gur, Dvir; Krivanek, Ondrej L.; Dellby, Niklas; Lovejoy, Tracy C.; Wolf, Sharon G.; Cohen, Hagai

    2016-03-01

    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.

  10. 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.

  11. 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.

  12. 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.

  13. Maskless, High-Precision, Persistent, and Extreme Wetting-Contrast Patterning in an Environmental Scanning Electron Microscope.

    PubMed

    Liimatainen, Ville; Shah, Ali; Johansson, Leena-Sisko; Houbenov, Nikolay; Zhou, Quan

    2016-04-13

    A maskless and programmable direct electron beam writing method is reported for making high-precision superhydrophilic-superhydrophobic wetting patterns with 152° contact angle contrast using an environmental scanning electron microscope (ESEM). The smallest linewidth achieved is below 1 μm. The reported effects of the electron beam induced local plasma may also influence a variety of microscopic wetting studies in ESEM. PMID:26880568

  14. 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

  15. 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.

  16. [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

  17. 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.

  18. A radial mirror analyzer for scanning electron/ion microscopes

    NASA Astrophysics Data System (ADS)

    Hoang, Hung Quang; Khursheed, Anjam

    2011-04-01

    This paper presents a high-resolution transmittance electron energy analyzer suitable for use as an attachment inside the specimen chambers of scanning electron/ion microscopes. The analyzer uses a rotationally symmetric electric field distribution to transport electrons/ions emitted from a central point source in a radial direction on to a ring-shaped collection/detection area. The analyzer is designed to fit around a conical shaped objective lens pole-piece/electrode, allowing for a relatively short minimum working distance, 5 mm or less. Simulation results for the analyzer design predict that it will have a relative energy resolution of 0.025% for an entrance angular spread of ±6°, around an order of magnitude better then the well-known Cylindrical Mirror Analyzer (CMA). The analyzer design allows for a parallel mode of operation in which the energy bandwidth on a conical shaped detection plane is predicted to be as high as 32% (±16%) of the central-band energy. On a flat ring-shaped detection plane, the energy bandwidth is predicted to be around 12% (±6%) of the central-band energy, over which the simulated relative energy resolution remains below 0.06% for angular spreads of ±6°.

  19. 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

  20. Electron microscopic studies of the antiferroelectric phase in Sr 0.60Ca 0.40TiO 3 ceramic

    NASA Astrophysics Data System (ADS)

    Anwar, Shahid; Lalla, N. P.

    2008-05-01

    The structural variants and their coexistence across the antiferroelectric phase transition in Sr 0.60Ca 0.40TiO 3 ceramic has been studied through transmission electron microscopy (TEM) at room temperature and ˜100 °C. A clear evidence of the presence of superlattice reflections, corresponding to the cell doubling along the c-axis of Pbnm (or b-axis along Pnma), occurring during paraelectric to antiferroelectric transition, has been obtained through selected area electron diffraction, convergent beam electron diffraction and lattice-resolution imaging. Coexistence of the Pbnm and Pbcm phases at room temperature has been observed and attributed to the strain/disorder-induced broadening of the first-order antiferroelectric phase transition. Drastic changes in the domain structure during Pbnm to Pbcm transformation have been observed. This clearly indicates that the antiferrodistortive transition responsible for the occurrence of the antiferroelectric phase is of completely different origin and it is not just an additional follow-up of the already-existing ordering due to a-a-c+ tilt schemes in the Pbnm domain. Thermal cycling studies on microstructural changes indicate some kind of memory mechanism, which retains the memory of the original a-a-c+ tilt schemes in the Pbnm phase. This has been attributed to the symmetry conforming short-range order (SC-SRO) of the point defects.

  1. 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.

  2. 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

  3. 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.

  4. Chemically twinned phases in the Ag 2S-PbS-Bi 2S 3 system.Part I. Electron microscope study

    NASA Astrophysics Data System (ADS)

    Skowron, A.; Tilley, R. J. D.

    1990-04-01

    Phases in the PbS-rich region of the Ag 2S-PbS-Bi 2S 3 system have been studied by high resolution transmission electron microscopy. In samples quenched from the melt or melted and annealed at 773 or 973 K a number of new chemically twinned phases have been found. Their structures contain galena-like slabs four-, five-, seven-, and eight-octahedra wide, joined along twin planes. Ordered phases predominate in the PbS-rich region of the phase diagram, while both ordered and disordered intergrowths occur in the PbS-poor region. The role of Ag in stabilizing slabs of galena-like material five- and eight-octahedra wide and its function in the formation of these twinned phases is discussed.

  5. Light and electron microscopic study of the eyelids, conjunctiva-associated lymphoid tissue and lacrimal gland in Bilgorajska Goose (Anser anser).

    PubMed

    Klećkowska-Nawrot, Joanna; Nowaczyk, Renata; Goździewska-Harłajczuk, Karolina; Barszcz, Karolina; Kowalczyk, Artur; Łukaszewicz, Ewa

    2016-01-01

    Normal structure of the accessory organs of the eye is essential for normal eye physiology. Among the most important accessory organs of the eye are the eyelids, the conjunctiva-associated lymphoid tissue (CALT) and the lacrimal gland (LG). The aim of this study was to demonstrate the histological structure of the eyelids and LG by histochemical and ultrastructural analysis. The study was performed on 13 adult female Bilgorajska geese. Eyelid samples were stained with the Alcian blue (AB pH 2.5) and periodic acid-Schiff (PAS) methods. Staining methods used for LG were AB pH 2.5, aldehyde fuchsin (AF), PAS and Hale's dialysed iron (HDI). Within the connective tissue of the eyelids, well-developed, diffuse, CALT follicles were observed, mostly under the conjunctival epithelium. Numerous lymphocytes were present within loose connective tissue. Staining of the eyelids with the PAS method demonstrated the presence of goblet cells of a mucous nature, and AB pH 2.5 staining indicated the presence of sulfated acid mucopolysaccharides. PAS staining of LG revealed the presence of secretory cells containing weakly PAS-positive granules. All epithelial cells of the corpus glandulae and the duct systems reacted positively to AB pH 2.5. HDI staining detected the presence of carboxylated acid mucopolysaccharides. Transmission electron microscopy investigations revealed two types of secretory epithelial cells in LG. Both types of LG cells contained drop-like secretory vesicles of different sizes with low or high electron density in cytoplasm, as well as small and large lipid vacuoles, and numerous small primary lysosomes. PMID:25673221

  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. Observation of an amalgam-bonded tooth through a scanning electron microscope.

    PubMed

    Orosa, Jose Luis B

    2003-01-01

    Bonding dental amalgam to tooth reduces the occurrence of marginal leakage, fracture and sensitivity. However, most studies of amalgam bonding have made use of resin cements and the conventional three-bottle bonding agents. In this study, a newer, single-bottle bonding agent was used to bond amalgam both to dentin and enamel. Interfaces of bonded amalgam and unbonded amalgam were observed under the scanning electron microscope. PMID:13677864

  8. 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.

  9. 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

  10. Differences in Endothelial Injury After Balloon Angioplasty, Insertion of Balloon-Expanded Stents or Release of Self-Expanding Stents: An Electron Microscopic Experimental Study

    SciTech Connect

    Harnek, Jan; Zoucas, Evita; Carlemalm, Erik; Cwikiel, Wojciech

    1999-01-15

    Purpose: To evaluate which of six different commonly available stents inserted into an artery without percutaneous transluminal angioplasty (PTA) causes the least endothelial damage. To compare the degree of endothelial injury after insertion of such a stent with injury caused by PTA. Methods: Twelve healthy pigs were used in the experiments. In the first part of the study six different types of stents were inserted into the common iliac arteries. In the second part of the study self-expanding stents with large spaces between the wires were used. PTA was performed in the contralateral iliac artery. The pigs were killed immediately after the procedure and resected specimens examined after fixation, using scanning electron microscopy. Results: All procedures but two were accomplished successfully. More endothelium was preserved after insertion of self-expanding stents with large spaces between the wires, compared with stents with small spaces and balloon-expanded stents. After insertion of self-expanding stents with large spaces, 50.1% {+-} 16.4% of the endothelium remained intact, compared with only 5.6% {+-} 7.7% after PTA. The difference was statistically significant (p < 0.001). Conclusion: Self-expanding stents with large spaces between the wires, inserted without PTA, cause less damage to the endothelium than other stents and significantly less damage than PTA.

  11. Node of Ranvier formation along fibres regenerating through silicone tube implants: a freeze-fracture and thin-section electron microscopic study.

    PubMed

    Le Beau, J M; Powell, H C; Ellisman, M H

    1987-06-01

    Thin-section and freeze-fracture electron microscopy have been used to examine the morphogenesis of the node of Ranvier in peripheral nerves regenerating through silicone tubes. A major question posed by this study is whether node formation in fibres regenerating across a gap recapitulates that occurring in normal development. Node formation occurs concurrently with myelination and follows a similar spatial gradient of progression from a proximal to distal direction along the regenerated nerve. Presumptive nodal sites appear prior to myelin formation and are identified as a prominent subaxolemmal density in thin sections and axonal particle patches in freeze-fracture. Following the appearance of presumptive nodes in regenerating fibres, dimeric particles are inserted into the axolemma adjacent to the node. These particles are in close apposition to the overlying Schwann cell terminal processes and with maturity adopt the same circumferential orientation seen in adult nodes. The nodal axolemma of regenerating fibres shows a characteristic increase in the prominence of its subaxolemmal densification and number of heterogeneously sized particles. Mature regenerated nodes demonstrate a complete annulus of nodal particles indistinguishable from control nodes. The results of the present study show that the nodal architecture of regenerating fibres is a faithful reconstruction of normal mature nodes, thus indicating that the morphological correlates associated with saltatory conduction at the node are present in regenerated nodes. PMID:3612184

  12. Three-dimensional organization of the hepatic artery terminal branches: a scanning electron microscopic study of vascular corrosion casts of rat liver.

    PubMed

    Pannarale, Luigi; Onori, Paolo; Borghese, Federica; Conte, Davide; Gaudio, Eugenio

    2007-01-01

    The hepatic artery plays an important role in the nourishment of liver parenchyma. The arterial distribution generates debate on where the artery terminates in the liver although is accepted that terminal branching of hepatic artery opened into sinusoids and form arterio-portal anastomosis. This implies that sinusoids are fed by both arterial and portal vessels characterized by different pressures. The presence of a double feeding to the sinusoids from the vena porta, at a pressure of 6-7 cm H2O, and from the hepatic artery, at a pressure of 12-25 cm H2O, has generated many studies for the need to explain the prevalence of flow from the vena porta. For this reason, we have studied the terminal hepatic artery branches in the rat by using special microvascular corrosion casting procedure which makes possible to better follow the hepatic artery terminal branches. Twelve young sexually mature male and female Wistar rats were used in this study. More than one hundred vascular corrosion casts of terminal hepatic arterioles were studied by Scanning Electron Microscopy. Histological samples were prepared using standard techniques for light microscopy. The experimental approach allow to easily follow the three-dimensional course of hepatic artery branches which is extremely difficult in standard injections. In all our observations of the rat liver vascular corrosion casts, terminal hepatic artery branches do not end directly in the sinusoidal beds. Terminal hepatic artery branches end into peribiliary plexus, periportal plexus and single capillaries of the portal space. We have not found any arterio-venous shunt nor any arterial vessel flowing into a venous vessel or a sinusoid. This means that only venous blood at a lowered pressure reaches the vena porta branches and the sinusoids. PMID:17580655

  13. 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.

  14. Electron microscopic study on the lipid content of intramitochondrial granules in proximal convoluted tubule of guinea pig kidney and their ability to accumulate calcium ions.

    PubMed

    Erkoçak, A

    1977-01-01

    The intramitochondrial dense granules of the kidney proximal tubule fixed with OsO4 are osmiophilic since they are bleached by H2O2 treatment and they disappear after glutaraldehyde fixation alone. Following ethanol extraction and subsequent osmification these granules become invisible but pure aceton treatment does not greatly alter their osmiophilia. The findings suggests that the osmiophilic intramitochondrial granules are rich in phospholipids. When the kidney cortex is incubated in the presence of calcium of acetate, calcium accumulates on the intramitochondrial granules increasing their size and number. The intramitochondrial granules are found more frequently in tissues where the transport of water or ions is big. They contribute to the sodium transport (RIEDEL, BUCHER and ERKOCAK 1968). They are composed mainly of neutral lipids (SANZONE, SWARTZENDRUBER and SNYDER 1970) and phospholipids (WENDEL and BARNARD 1974). They are formed by the precipitation of calcium and other ions (GREENAWALT, ROSSI and LEHNINGER 1964; Peachey 1964). in this present work the structure of dense intramitochondrial granules has been studied regarding electron opaque materials. This way on one hand the lipids and the nucleic acids have been investigated, on the other hand the intramitochondrial granules have been loaded with calcium, a cation showing density in precipitated form and found in great amount into the cell. PMID:409048

  15. 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

  16. 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

  17. Immunolocalization of thymosin alpha 1, thymopoietin and thymulin in mouse thymic epithelial cells at different stages of culture: a light and electron microscopic study.

    PubMed Central

    Fabien, N; Auger, C; Monier, J C

    1988-01-01

    The secretory evolution of the thymic hormones (thymulin, thymosin alpha 1 and thymopoietin) in cultured thymic reticuloepithelial cells (TREC) was studied by immunocytochemical techniques using monoclonal anti-thymulin or anti-thymosin alpha 1 and polyclonal anti-thymopoietin antibodies (Ab). The culture of TREC was performed with a medium where L-valine was replaced by D-valine, thus ensuring rapid and selective development of these cells. The number of thymulin, thymosin alpha 1 or thymopoietin-containing cells increased progressively from Day 6 to Day 12 of the culture. The localization of the three thymic hormones within the TREC also varied according to the age of the culture. By light microscopy the staining of the three hormones was localized in some cytoplasmic granules at the beginning of the culture and at Day 90, while at Day 12 it was throughout the cytoplasm. In electron microscopy these localizations corresponded respectively to vacuoles of different sizes and to cytosol. All these results show that the synthesis and excretion of thymulin, thymosin alpha 1 and thymopoietin evolve during the development of TREC in culture. Images Figure 1 Figure 2 PMID:3284819

  18. NMR solution studies of hamster galectin-3 and electron microscopic visualization of surface-adsorbed complexes: evidence for interactions between the N- and C-terminal domains.

    PubMed

    Birdsall, B; Feeney, J; Burdett, I D; Bawumia, S; Barboni, E A; Hughes, R C

    2001-04-17

    Galectin-3, a beta-galactoside binding protein, contains a C-terminal carbohydrate recognition domain (CRD) and an N-terminal domain that includes several repeats of a proline-tyrosine-glycine-rich motif. Earlier work based on a crystal structure of human galectin-3 CRD, and modeling and mutagenesis studies of the closely homologous hamster galectin-3, suggested that N-terminal tail residues immediately preceding the CRD might interfere with the canonical subunit interaction site of dimeric galectin-1 and -2, explaining the monomeric status of galectin-3 in solution. Here we describe high-resolution NMR studies of hamster galectin-3 (residues 1--245) and several of its fragments. The results indicate that the recombinant N-terminal fragment Delta 126--245 (residues 1--125) is an unfolded, extended structure. However, in the intact galectin-3 and fragment Delta 1--93 (residues 94--245), N-terminal domain residues lying between positions 94 and 113 have significantly reduced mobility values compared with those expected for bulk N-terminal tail residues, consistent with an interaction of this segment with the CRD domain. In contrast to the monomeric status of galectin-3 (and fragment Delta 1--93) in solution, electron microscopy of negatively stained and rotary shadowed samples of hamster galectin-3 as well as the CRD fragment Delta 1--103 (residues 104--245) show the presence of a significant proportion (up to 30%) of oligomers. Similar imaging of the N-terminal tail fragment Delta 126--245 reveals the presence of fibrils formed by intermolecular interactions between extended polypeptide subunits. Oligomerization of substratum-adsorbed galectin-3, through N- and C-terminal domain interactions, could be relevant to the positive cooperativity observed in binding of the lectin to immobilized multiglycosylated proteins such as laminin. PMID:11294654

  19. Development of the areola in the early placenta of the one-humped camel (Camelus dromedarius): a light, scanning and transmission electron microscopical study.

    PubMed

    Abd-Elnaeim, M M M; Saber, A; Hassan, A; Abou-Elmagd, A; Klisch, K; Jones, C J P; Leiser, R

    2003-12-01

    This study aimed to elucidate development of the areola in the early dromedary placenta in comparison with that of the pig and mare. Placental tissues from 25 pregnant camels were obtained from Cairo abattoir and prepared for light, scanning and transmission electron microscopy by routine methods. Vascular casts were made by injection of 4 : 1 liquid plastic mixture of mercox and methylmethacrylate. Areolar formation was first observed at 4.5 cm curved-crown-rump CVR length, while by 5-9 cm CVR length, the endometrial surface was uneven and studded with numerous uterine gland openings, where corresponding foetal areolae were barely detectable and the foetal areolar cells were of variable appearance and covered with long microvilli. At 10-13 cm CVR length the uterine gland openings developed irregular folds and the maternal areolar cells showed numerous apical blebs. At 14-29 cm CVR length the foetal areolae showed a great increase in height at the expense of their width. At 30-34 cm (CVR) length the maternal areolae appeared discoid and sharply demarcated from the surrounding inter-areolar tissues and the foetal areolae were rounded to irregular in shape with well-developed areolar rims. The vascular casts showed a widely meshed capillary network on the maternal areola, connecting with the pre- and post-capillary vessels, whereas the foetal side showed a relatively dense capillary meshwork. These studies indicate that the areola in the placenta of the one-humped camel is of the regular type like in the pig, and is poorly vascularized. PMID:14651479

  20. 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

  1. Comparison of fibrin clot adhesion to dentine conditioned with citric acid, tetracycline, and ethylene diamine tetra acetic acid: An in vitro scanning electron microscopic study

    PubMed Central

    Minocha, Tanuj; Rahul, Aparna

    2012-01-01

    Aim: The purpose of this study was to evaluate and compare the root surface changes subsequent to the application of citric acid, tetracycline, Ethylenediaminetetraacetic acid (EDTA), and the combination of citric acid and tetracycline, and its influence on the adhesion of a fibrin clot with and without mild disruptive forces. Materials and Methods: A total of 100 periodontally diseased root specimens were grouped into Saline (control Group I), 24% EDTA gel (Group-II), Citric acid (Group-III), Tetracycline (Group IV), and Citric acid + tetracycline (Group V) treatment groups containing 20 in each. After root conditioning, fresh human blood was applied to each root specimen and was allowed to clot. Ten specimens in each group were rinsed in phosphate-buffered saline and designated as ′Non-agitated′. The remaining ten specimens from each group were rinsed in phosphate-buffered saline on a rotary shaker and designated as ′Agitated′. The roots were processed for scanning electron microscopy (SEM) to assess and compare the clot adhesion on them. The scores were compared through standard statistical packages. Results: The highest mean blood clot adhesion score was observed in roots treated with a combination of citric acid and tetracycline, whereas, the least score was observed in roots treated with saline. Conclusion: The root specimens treated with the combination of citric acid and tetracycline as well as citric acid alone, best supported the fibrin clot. Tetracycline alone appeared to be less effective in supporting the clot. EDTA gel of 24% was least effective to promote the adhesion of a fibrin clot. PMID:23162325

  2. Fetomaternal attachment and anchorage in the early diffuse epitheliochorial placenta of the camel (Camelus dromedarius). Light, transmission, and scanning electron microscopic study.

    PubMed

    Abd-Elnaeim, M M; Pfarrer, C; Saber, A S; Abou-Elmagd, A; Jones, C J; Leiser, R

    1999-01-01

    Placentae of 22 one-humped camel concepti with crown-rump lengths (CRL) ranging from 2.5 to 26 cm were studied. The placentae were processed for light, transmission and scanning electron microscopy of exposed surfaces and microvascular corrosion casts. In very early stages of pregnancy (2.5-4.5 cm CRL) three froms of fetomaternal interrelationship are described. (1) Precontact, where the mononuclear trophoblast cells are still separated from the uterine epithelium by a gap containing interareolar histotroph. Both fetal and maternal epithelia develop apical ectoplasmic pads in this location. (2) Apposition, where microvilli of the apical cell membrane of the trophoblast contact the uterine epithelium focally. Multinuclear trophoblast giant cells develop beside the population of already present mononuclear trophoblast cells. Uterine ectoplasmic pads can be observed. (3) Adhesion occurs when apical cell membranes of fetal and maternal epithelia adhere to each other closely, thus forming a 'normal' intercellular space of 20 nm width, without any intervening uterine luminal space. Microvillous interdigitation in this location varies from a non-microvillous 'smooth adhesion', to a distinctly villiform 'rough adhesion', and a 'semismooth adhesion' is achieved when trophoblastic microvilli make intimate contact with the non-microvillous uterine apical cell membranes of ectoplasmic pads. This fetomaternal attachment process is sufficient until the conceptus reaches approximately 9 cm CRL. Then, from 10 to 13 cm CRL, additional anchorage of the placenta to the endometrium is accomplished by the growth of temporary grooves and ridges of the allantochorion and the endometrium, which indent each other in a complementary fashion. The height of these groove-ridge structures increases gradually in 14 to 18 cm CRL fetuses, and they also widen at about 25 cm CRL, thus forming globular fetal troughs and irregular, thick maternal ridges. These together create units responsible for

  3. 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…

  4. Scanning electron microscopic analysis of incinerated teeth: An aid to forensic identification

    PubMed Central

    Pol, Chetan A; Gosavi, Suchitra R

    2014-01-01

    Background: Forensic dental identification of victims involved in fire accidents is often a complex and challenging endeavor. Knowledge of the charred human dentition and residues of restorative material can help in the recognition of bodies burned beyond recognition. Aim: To observe the effects of predetermined temperatures on healthy unrestored teeth and different restorative materials in restored teeth, by scanning electron microscope, for the purpose of identification. Materials and Methods: The study was conducted on 135 extracted teeth, which were divided into four groups. Group 1-healthy unrestored teeth, group 2-teeth restored with all ceramic crowns, group 3-teeth restored with class I composite resin and group 4-teeth restored with class I glass ionomer cement (GIC). Results: The scanning electron microscope is useful in the analysis of burned teeth, as it gives fine structural details, requires only a small sample and does not destroy the already fragile specimen. Conclusion: Scanning electron microscope can be a useful tool for the characterization and study of severely burnt teeth for victim identification. PMID:24959034

  5. Distribution of 125I-galanin binding sites, immunoreactive galanin, and its coexistence with 5-hydroxytryptamine in the cat spinal cord: Biochemical, histochemical, and experimental studies at the light and electron microscopic level

    SciTech Connect

    Arvidsson, U.; Ulfhake, B.; Cullheim, S.; Bergstrand, A.; Theodorson, E.; Hoekfelt, T. )

    1991-06-01

    The distribution of galanin-like immunoreactivity (GAL-LI) in the spinal cord of the cat was studied by use of indirect histochemistry and the peroxidase-antiperoxidase (PAP) technique. In the ventral horn GAL-immunoreactive (IR) axonal fibers and terminals were most frequent in the ventral part of the motor nucleus. The GAL-IR axons also contained 5-hydroxytryptamine (5-HT)-LI, and they disappeared after spinal cord transection. It was concluded that these GAL-IR fibers belong to the serotoninergic bublospinal pathway. In the medulla oblongata from normal cats, scattered GAL-IR cell bodies were encountered within the nucleus raphe obscurus and nucleus raphe pallidus. Electron microscopic observations revealed that the fine structure of the GAL-IR axonal boutons in the motor nucleus was similar to that of 5-HT-IR boutons with a varying number of immunoreactive large dense core vesicles. The postsynaptic element in all cases studied was a dendrite. A dense GAL-IR axonal plexus was found in the superficial laminae I-II of the dorsal horn. Coexistence was found between the GAL- and substance P-LI in fibers within the dorsal horn plexus. Spinal cord transection did not alter the pattern of GAL-LI in the dorsal horn, while the vast majority of GAL-IR axonal swellings disappeared following dorsal root sectioning. Electron microscopic observations in lamina II (substantia gelatinosa) revealed that the GAL-IR axonal terminals could be divided into two main groups. One with small to medium-sized axonal boutons formed synaptic contacts with both dendritic and axonal profiles. The other formed the central axon terminals of glomeruli, suggesting that GAL-LI may be present in C-type primary afferents. Numerous small GAL-IR cell bodies were encountered in laminae II and III. GAL-IR cell bodies were also observed in lamina X.

  6. 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.

  7. The morphology of the cement gland apparatus of larval Pterophyllum scalare Cuv. & Val. (Cichlidae, Teleostei). Histological, transmission- and scanning electron microscopic studies.

    PubMed

    Bennemann, R; Pietzsch-Rohrschneider, I

    1978-10-30

    The cement gland apparatus of newly hatched Pterophyllum scalare Cuv. & Val. was examined by histology, scanning and transmission electron microscopy. The whole organ is composed of three pairs of endoepithelial, ductless glands, which cause prominent elevations on the larval head and are found in a specific arrangement. Each single gland is represented by an aggregation of elongated, tubular secretory cells surrounding a pyriform acinus. It overlies a basal lamina and is covered by the outer layer of the bilaminar embryonic epidermis. Two different types of secretory cells can be distinguished. One type is restricted to the bottom of the cavity. It is characterized by multiform cytoplasmic protrusions, which project into the gland's cavity. The secretory granules contain a network of light filamentous material. The second type constitutes the side wall of the acinus. It does not develop any protrusions. The contents of the secretory granules is of very high and homogeneous electron density. The mechanism of extrusion is discussed for both cell types. All secretory cells show a strong PAS-reaction. In SEM a circular microridge pattern with attached mucus globules can be recognized on the larval epithelial surface. PMID:728956

  8. 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.

  9. A Comparative High-Resolution Electron Microscope Study of Ag Clusters Produced by a Sputter-Gas Aggregation and Ion Cluster Beam Technique

    NASA Astrophysics Data System (ADS)

    Hohl, Georg-Friedrich; Hihara, Takehiko; Sakurai, Masaki; Oishi, Takashi; Wakoh, Kimio; Sumiyama, Kenji; Suzuki, Kenji

    1994-03-01

    Ag clusters were formed by a sputter-gas-aggregation process [H. Haberland et al..: J. Vac. Sci. Technol. A 10 (1992) 3266] and the ionized cluster beam (ICB) [T. Takagi: Ionized-Cluster Beam Deposition and Epitaxy (Noyes, Park Ridge, 1988)] technique. The Ag clusters deposited on collodion-coated microgrids were investigated by high-resolution transmission electron microscopy. The diameter of those clusters, d, ranges from 1 nm up to about 10 nm for specimens produced by the sputter-gas aggregation technique, depending on the sputter condition and the deposition time. Comparable times of the ICB deposition lead to a broader distribution up to d≈20 nm, suggesting the formation of islands with extremely flat shapes. High percentages of crystalline particles obtained by both techniques are either single crystals or multiple twins with clear lattice images.

  10. Transmission Electron Microscope Study on Electrodeposited Gd2O3 and Gd2Zr2O7 Buffer Layers forYBa2Cu307-..delta.. Superconductors

    SciTech Connect

    Zhao, W.; Norman, A.; Phok, S.; Bhattacharya, R.

    2008-01-01

    We have investigated the microstructures of electrodeposited Gd{sub 2}O{sub 3} (GO) and Gd{sub 2}Zr{sub 2}O{sub 7} (GZO) buffer layers for YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) superconductors with conventional transmission electron microscopy (TEM). A high density of nanoscale voids was present in the GZO buffer layers. No voids were observed in GO buffer layers grown on GZO. YBCO superconductor grown on the GO/GZO buffer layer structure produced a critical current density (J{sub c}) of 3.3 x 10{sup 6} A/cm{sup 2} at 77 K in zero field.

  11. 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

  12. Numerical study of a microscopic artificial swimmer

    NASA Astrophysics Data System (ADS)

    Gauger, Erik; Stark, Holger

    2006-08-01

    We present a detailed numerical study of a microscopic artificial swimmer realized recently by Dreyfus in experiments [Dreyfus , Nature 437, 862 (2005)]. It consists of an elastic filament composed of superparamagnetic particles that are linked together by DNA strands. Attached to a load particle, the resulting swimmer is actuated by an oscillating external magnetic field so that it performs a nonreciprocal motion in order to move forward. We model the superparamagnetic filament by a bead-spring configuration that resists bending like a rigid rod and whose beads experience friction with the surrounding fluid and hydrodynamic interactions with each other. We show that, aside from finite-size effects, its dynamics is governed by the dimensionless sperm number, the magnitude of the magnetic field, and the angular amplitude of the field’s oscillating direction. Then we study the mean velocity and the efficiency of the swimmer as a function of these parameters and the size of the load particle. In particular, we clarify that the real velocity of the swimmer is influenced by two main factors, namely the shape of the beating filament (determined by the sperm number and the magnetic-field strength) and the oscillation frequency. Furthermore, the load size influences the performance of the swimmer and has to be chosen as a compromise between the largest swimming velocity and the best efficiency. Finally, we demonstrate that the direction of the swimming velocity changes in a symmetry-breaking transition when the angular amplitude of the field’s oscillating direction is increased, in agreement with experiments.

  13. 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

  14. 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.

  15. Electron microscopic observation of the sagittal structure of Drosophila mature sperm.

    PubMed

    Yasuno, Yusaku; Yamamoto, Masa-Toshi

    2014-09-01

    Observation of sperm development and determination of their morphological characteristics are very important to the understanding of phylogenetic relationships and the study of sperm function during fertilization. Although ultrastructural studies of sperm development in the testes of the fruit fly Drosophila have been performed, there are few reports describing electron microscopic morphology of mature sperm, that is, those released from the testes to the seminal vesicles. Here, we present the first report of the sagittal organization of Drosophila sperm head and neck regions by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The head and tail structures of a mature sperm, for example, the acrosome, nucleus, and flagellum, were easy to distinguish by the morphological characteristics of the sperm surface by SEM. The morphological relationships between the surface and internal structures of mature sperm were confirmed by observing longitudinal sections with TEM. Our approach overcame the technical difficulties involved in sample preparation for electron microscopic observation of the Drosophila mature sperm head, and therefore, this study serves as an important foundation for future genetic dissection of sperm ultrastructure and function in male sterile mutants. PMID:24911661

  16. Frequency-doubled Alexandrite laser for use in periodontology: a scanning electron microscopic investigation

    NASA Astrophysics Data System (ADS)

    Rechmann, Peter; Hennig, Thomas

    1996-12-01

    During prior studies it could be demonstrated that engaging a frequency double Alexandrite-laser allows a fast and strictly selective ablation of supra- and subgingival calculus. Furthermore, the removal of unstained microbial plaque was observed. First conclusions were drawn following light microscopic investigations on undecalcified sections of irradiated teeth. In the present study the cementum surface after irradiation with a frequency doubled Alexandrite-laser was observed by means of a scanning electron microscope. After irradiation sections of teeth were dried in alcohol and sputtered with gold. In comparison irradiated cementum surfaces of unerupted operatively removed wisdom teeth and tooth surfaces after the selective removal of calculus were investigated. A complete removal of calculus was observed as well as a remaining smooth surface of irradiated cementum.

  17. 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

  18. 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

    Kiama, S G; Bhattacharjee, J; Maina, J N; Weyrauch, K D

    1994-12-01

    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. PMID:7649799

  19. The versatile electron microscope: an ultrastructural overview of autophagy.

    PubMed

    Biazik, Joanna; Vihinen, Helena; Anwar, Tahira; Jokitalo, Eija; Eskelinen, Eeva-Liisa

    2015-03-01

    Both light microscopy (LM) and electron microscopy (EM) are able to reveal important information about the formation and function of various autophagic compartments. In this article we will outline the various techniques that are emerging in EM, focusing on analyzing three-dimensional morphology, collectively known as volume electron microscopy (volume EM), as well as on methods that can be used to localize proteins and antigenic epitopes. Large cell volumes can now be visualized at the EM level by using one of the two complementary imaging techniques, namely Serial Block-face Scanning Electron Microscopy (SB-SEM) or Focused Ion Beam Scanning Electron Microscopy (FIB-SEM). These two block-face imaging methods reveal ultrastructural information from all membrane-bound organelles such as autophagic compartments to be visualized in a three-dimensional space, in association with their surrounding organelles. Another method which falls into the volume EM category is dual-axis electron tomography (ET). This method is more suited to reconstructing smaller volumes from areas of interest that require nano-structural detail to be confirmed such as membrane contact sites (MCSs) between autophagic compartments and various organelles. Further to this, to complement the morphological identification of autophagic compartments, immunolabeling can be carried out at the EM level to confirm the nature of various autophagic compartments depending on the localization of various antigens at a sub-cellular level. To determine this, various immunolabeling techniques can be carried out, namely the pre-embedding or the post-embedding immunolabeling methods. Examples of both of these methods will be described in this chapter. Correlative light-electron microscopy (CLEM) can be used to visualize the same autophagic organelles under the LM, followed by high-resolution imaging under the EM. Finally, cryofixation has revolutionized the EM field by allowing rapid immobilization of cells and

  20. Transmission electron microscope study of the ultrastructural changes induced in the tegument and gut of Fasciola hepatica following in vivo drug treatment with clorsulon.

    PubMed

    Meaney, M; Fairweather, I; Brennan, G P; Forbes, A B

    2004-02-01

    Using transmission electron microscopy (TEM), both the tegument and gut of Fasciola hepatica were examined in an effort to identify and characterise the ultrastructural changes induced following treatment with the flukicidal drug clorsulon. Male Sprague-Dawley rats infected with F. hepatica were dosed orally at 8-8.5 weeks post-infection with clorsulon at a concentration of 12.5 mg/kg body weight. After 24, 48 and 72 h, rats were sacrificed by cervical dislocation and mature flukes recovered from the bile ducts. After 24 h treatment in vivo, disruption of the tegumental syncytium was concentrated at the apex of the syncytium where a dark band consisting of numerous secretory bodies was present. Some blebbing of the apex had also occurred, "open" bodies were present in this region and the mitochondria were slightly swollen. In the cell bodies, swelling of the mitochondria and their cristae had also occurred and the Golgi complexes appeared to be smaller than normal. The disruption seen after 48 h treatment in vivo was similar but more severe: the frequency of blebbing had increased, as had the number of "open" bodies and the swelling of the mitochondria. Vacuoles had begun to appear in the syncytium-both autophagic and electron-lucent-and swelling of the mucopolysaccharide masses around the basal infolds had occurred. Lipid droplets were observed occasionally. In the cell bodies, autophagic vacuoles had begun to appear and swelling of the mitochondria had increased in severity. After 72 h treatment in vivo, more severe disruption was seen in the tegumental syncytium in which widespread swelling and blebbing of the apex was apparent. The basal infolds had become very badly swollen in a number of specimens and damage to the spines was evident. The mitochondria remained swollen, as did the mucopolysaccharide masses around the basal infolds. Lipid droplets were more frequently observed in the syncytium. In the tegumental cells, swelling of the mitochondria was greater

  1. High-resolution scanning electron-microscopic studies on the three-dimensional structure of mitochondria and sarcoplasmic reticulum in the different twitch muscle fibers of the frog.

    PubMed

    Ogata, T; Yamasaki, Y

    1987-12-01

    The three-dimensional structure of the mitochondria and sarcoplasmic reticulum (SR) in the three types of twitch fibers, i.e., the red, white and intermediate skeletal muscle fibers, of the vastus lateralis muscle of the Japanese meadow frog (Rana nigromaculata nigromaculata Hallowell) was examined by high resolution scanning electron microscopy, after removal of the cytoplasmic matrices. The small red fibers have numerous mitochondrial columns of large diameter, while the large white fibers have a small number of mitochondrial columns of small diameter. In the medium-size intermediate fibers, the number and diameter of the mitochondrial columns are intermediate between those of the red and white fibers. In all three types of fibers, the terminal cisternae and transverse tubules form triads at the level of each Z-line. The thick terminal cisternae continue into much thinner flat intermediate cisternae, through a transitional part where a row of tiny indentations can be observed. Numerous slender longitudinal tubules originating from the intermediate cisternae, extend longitudinally or obliquely and form elongated oval networks of various sizes in front of the A-band, then fuse to form the H-band collar (fenestrated collar) around the myofibrils. On the surface of the H-band collar, small fenestrations as well as tiny hollows are seen. The three-dimensional structure of SR is basically the same in all three muscle fiber-types. However, the SR is sparse on the surface of mitochondria, so the mitochondria-rich red fiber has a smaller total volume of SR than the mitochondria-poor white fiber. The volume of SR of the intermediate fiber is intermediate between other the two. PMID:3690630

  2. 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

  3. The morphology of the lung of the black mamba Dendroaspis polylepis (Reptilia: Ophidia: Elapidae). A scanning and transmission electron microscopic study.

    PubMed

    Maina, J N

    1989-12-01

    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

  4. Light and scanning electron microscopic study on the lingual papillae and their connective tissue cores of the Cape hyrax Procavia capensis

    PubMed Central

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

    2008-01-01

    We examined the epithelial surface and connective tissue cores (CTCs) of each lingual papilla on the Paenungulata, Cape hyrax (Procavia capensis), by scanning electron microscopy and light microscopy. The tongue consisted of a lingual apex, lingual body and lingual root. Filiform, fungiform and foliate papillae were observed on the dorsal surface of the tongue; however, fungiform papillae were quite diminished on the lingual prominence. Moreover, no clearly distinguishable vallate papillae were found on the tongue. Instead of vallate papillae, numerous dome-like large fungiform papillae were arranged in a row just in front of the rather large foliate papillae. Foliate papillae were situated in the one-third postero-lateral margin of the lingual body. The epithelium of filiform papillae was covered by a keratinized layer with kerato-hyaline granules, whereas weak keratinization was observed on the interpapillary epithelium. The external surface of the filiform papillae was conical in shape. CTCs of the filiform papillae were seen as a hood-like core with a semicircular concavity in the anterior portion of each core. Large filiform papillae were distributed on the lingual prominence. The CTCs of large filiform papillae after exfoliation of their epithelium consisted of a concave primary core and were associated with several small protrusions. The surface of fungiform papillae was smooth and dome-like. After removal of the epithelium, CTCs appeared as a flower bud-like primary core and were associated with several protrusions that were arranged on the rim of the primary core. Several taste buds were found on the top of the dorsal part of the epithelium of both fungiform and large fungiform papillae. Well-developed foliate papillae were seen and numerous taste buds could be observed in the lateral wall of the epithelium in a slit-like groove. The morphological characteristics of the tongue of the Cape hyrax had similarities with other Paenungulata such as Sirenia

  5. Scanning Electron Microscope Characterization of Erosive Enamel in Human Teeth.

    PubMed

    Worawongvasu, Ratthapong

    2015-01-01

    This study aimed to examine the surface characteristics of erosive enamel in extracted human teeth by scanning electron microscopy. Morphologic changes in naturally eroded enamel depend on the stages of dental erosion. In its early stages, the enamel surfaces show a honeycomb appearance due to the dissolution of enamel rod ends. In its advanced stages, the erosive process involves the underlying dentin and the eroded dentin shows exposed dentinal tubules and the dentinal matrix may be exposed due to the dissolution of the peri- and intertubular dentin. Evidence of remineralization is seen at the early stage of natural dental erosion. PMID:26214120

  6. 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

  7. [Experimental analytical electron microscopic studies on the quantitative analysis of elemental concentrations in biological thin specimens and its application to dental science].

    PubMed

    Hirayama, A

    1990-08-01

    The aim of this study is to employ an energy dispersive X-ray spectrometer (EDS) in developing a computer software system for the quantitative analysis of elemental concentrations in biological specimens. The methods and the software were applied to the examination of the coronal dentin of human deciduous and permanent teeth. Results 1. Examination methods. Chemical compounds known for their calcium (Ca) and phosphorus (P) contents were used to determine optimum conditions for analysis. The following were the best analytical conditions: 100 kV accelerating voltage, 2 x 10(-10) A probe current, 10 ekV energy scale, 100 sec. counting time, and 100-150 nm section thickness. Under these conditions, it is possible to obtain statistically sufficient integral spectra values. By calculating with the computer software(t-factor) developed in this study, it was possible to arrive at analytical calcium and phosphorus concentration values that are very close to theoretical values. 2. Application to human dentin. Deciduous intertubular dentin contained 24.9% (w/w) Ca and 12.1% (w/w) P; peritubular dentin in the same teeth contained 30.7% (w/w) Ca and 15.3% (w/w) P. Permanent intertubular dentin contained 25.5% (w/w) Ca and 12.5% (w/w) P; peritubular dentin in the same teeth contained 34.5% (w/w) Ca and 16.9% (w/w) P. These results show that, in both permanent and deciduous teeth, concentrations of Ca and P are higher in peritubular than in intertubular dentin. Concentrations Ca and P in both peritubular and intertubular dentin are lower in deciduous than in permanent teeth. The computer software developed for this study differs from chemical analysis and may prove very useful in microanalysis of mineralized tissues on the basis of their ultrastructures. PMID:2134979

  8. Manual sonic-air and ultrasonic instrumentation of root canal and irrigation with 5.25% sodium hypochlorite and 17% Ethylenediaminetetraacetic acid: A scanning electron microscope study

    PubMed Central

    Koçani, Ferit; Kamberi, Blerim; Dragusha, Edmond

    2012-01-01

    Objectives: The objective of this study was to evaluate the effectiveness of manual, sonic-air and ultrasonic instrumentation with varying irrigation protocols on removal of the smear layer from root canal walls. Study Design: Sixty extracted single rooted human teeth stored in 0.5% saline were used. Periodontal soft tissues were removed followed by crown separation at the cementoenamel junction (CEJ). All the teeth were randomly divided into three groups. Group I was manually instrumented and irrigated with 5.25% sodium hypochlorite (NaOCl) alone and 17% Ethylenediaminetetraacetic acid (EDTA) alternately, same as sonically instrumented Group II and ultrasonically instrumented Group III. The controls for all groups were irrigated with saline solution. Results: Ultrasonic over the sonic-air and manual technique, and the use of a combination of two different solutions (17% EDTA and 5.25% NaOCl) alternatively yielded better outcome. Conclusions: Ultrasonic, sonic-air and manual instrumentation of the root canal and irrigation with combined solutions is effective in removal of the smear layer from the instrumented walls of the root canal. PMID:22557807

  9. Comparative morphology of the pectinate ligaments of domestic mammals, as observed under the dissecting microscope and the scanning electron microscope.

    PubMed

    Simones, P; De Geest, J P; Lauwers, H

    1996-10-01

    The pectinate ligaments of ten horses, two donkeys, five oxen, five sheep, ten goats, five dogs, five cats, thirty pigs and two rabbits were studied under the stereomicroscope and the scanning electron microscope. In the horse and the donkey, the pectinate ligament was very prominent and was characterized by sturdy interconnected strands and relatively small intertrabecular spaces. The pectinate ligaments of ruminants were composed of shorter strands, separated by relatively larger spaces. Fusion between adjacent strands, resulting in the formation of fenestrated sheets, was regularly observed in these species, in particular in the superior and inferior ocular segments. In the dog and the cat, the pectinate ligament consisted of slender strands that were separated by large intertrabecular spaces. The strands of the pectinate ligaments of the pig and the rabbit were shorter and their diameters were intermediate between those of the herbivores and the carnivores. The clinical relevance of the normal variability in the structure of the pectinate ligament and proposals for a uniform anatomical nomenclature are discussed. PMID:8915997

  10. Comparative evaluation of the length of resin tags, viscosity and microleakage of pit and fissure sealants – an in vitro scanning electron microscope study

    PubMed Central

    Prabhakar, A.R.; Murthy, Sankriti A.; Sugandhan, S.

    2011-01-01

    Introduction: In this era of preventive dentistry, many techniques are available for prevention of caries, such as plaque control, use of systemic and local fluorides and pit and fissure sealants. The rationale of pit and fissure sealants is that, when they are applied into the caries prone fissures, they penetrate and seal them from the oral environment. This study aims to correlate the relationship between the viscosity of the sealant, resin tag length and microleakage. Materials and Methods: 30 third molars were selected for study. The teeth were randomly divided into 3 groups. Group E: Embrace wetbond, H: Helioseal, G: Guardian seal. Teeth were cleaned with pumice prophylaxis and pretreated with acid etching and bonding agent. The respective pit and fissure sealants were applied. Teeth were placed in 1% methylene blue dye and sectioned mesio-distally into two halves. These were used to assess the microleakage using stereomicroscope and resin tag length using SEM. Viscosity was assessed using Brooke's field viscometer. Results: Viscosity was lowest for Embrace wetbond and highest for Guardian seal. Microleakage scores were highest with Guardian seal and lowest with Embrace wetbond. Resin tag lengths were longer with Embrace wetbond as compared to other groups. There is a definite negative correlation between viscosity, resin tag length and microleakage. Lower the viscosity, the longer were the resin tags and the microleakage decreased. Embrace wetbond pit and fissure sealant had lowest viscosity, longest resin tag length and lowest microleakage scores. Conclusion: Embrace wetbond appears to be compatible with residual moisture and ideal for use in children, where isolation is a problem. PMID:22346161

  11. The distribution of stellate cell descending axons in the rat cerebellum: a Golgi and a combined Golgi-electron microscopical study.

    PubMed Central

    Paula-Barbosa, M M; Tavares, M A; Ruela, C; Barroca, H

    1983-01-01

    Axonal descending branches of stellate cells in the molecular layer of the cerebellar cortex of the rat were studied by means of Golgi and combined Golgi-ultrastructural methods. Special attention was paid to those branches from more superficially located cell bodies. With the Golgi method, it was observed that the number of axons from stellate cells forming pericellular baskets and 'pinceaux' increases as their cell bodies come to lie deeper in the layer. With the combined Golgi-ultrastructural method, it was verified that the synaptic contacts established by these axons are identical to those of axons from basket cells, either contacting Purkinje cell bodies or lying around the axon initial segments, where they establish septate-like junctions. This overlapping of axonal territories between stellate and basket cells is in accordance with the hypothesis that these interneurons, although situated at different levels of the cerebellar molecular layer, may be genetically identical cells. Their diversity of form would depend on the cellular microenvironment present at the time of differentiation. Images Figs. 1-4 Figs. 5-7 Fig. 8 Fig. 9 Fig. 10 PMID:6668252

  12. 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

  13. [Comparative electron-microscopic study of 8 representatives of the genus Corynebacterium grown on solid nutrient medium during the stationary phase of development].

    PubMed

    Vysotskiĭ, V V; Mazurova, I K; Shmeleva, E A

    1976-09-01

    After 18 hours of growth on selective serum-agar medium C diphtheriae cultures with different toxicogenic activity, and also diphtheroid and Hoffmann's baccillus cultures were removed, washed of the remnants of the nutrient medium and fixed under cold conditions by two combined methods (with glutaric aldehyde-osmic acid--uranyl acetate, and potassium permeanganate--uranyl acetate). The preparations were studied in ultrathin sections. It appeared that corynebacteria had during the stationary phase of development a general structural plan characteristic of Gram positive microorganisms and for all the corynebacterium genus. Cells of diphtheria toxicognic strains had signs of the accelerated (in comparison with other strains) rate of development; the principal mass of toxicogenic cells after 18 hours of growth had morphological signs of the stage of rest. The majority of cells whose toxicogenicity was inconstant had an extensive microcapsule which was also a characteristic element of the diphtheroid and Hoffmann's bacillus ultrastructure. The total thickness of the walls in the cells of toxicogenic strains and of the strains whose toxicogenicity was inconstant constituted 190-200 A; in nontoxicogenic strains, diphtheroid and Hoffmann's bacillus it was from 230 to 320 A. Surface structures of corynebacteria were differentiated better in the cells with toxicogenic activity. In the majority of cells of nontoxicogenic strains and also diphtheroid and Hoffmann's bacillus individual wall layers were differentiated with difficulty. PMID:827882

  14. Morphological and scanning electron microscopic studies of the tongue of the Egyptian fruit bat (Rousettus aegyptiacus) and their lingual adaptation for its feeding habits.

    PubMed

    Abumandour, Mohamed M A; El-Bakary, Raafat M A

    2013-09-01

    This study was carried out on the tongues of 12 adult normal healthy Egyptian fruit bats of both sexes. The tongue is protrusible, elongated flat with a rounded apex and its wide and thickness increase gradually toward the lingual root. There are four types of lingual papillae; two mechanical and two gustatory. The tongue divided into three parts (anterior, middle and posterior), each part subdivides into three regions; two lateral regions and median region, in addition to the lingual apex to the anterior region. The lingual papillae close to the median region of the tongue were posteriorly directed toward the pharynx, while theses present on the lateral regions of the tongue are directed medioposteriorly. There are sex subtypes of the filiform papillae; three on the anterior part (small, conical and giant), two on the middle part (cornflower and leaf-like papillae) while the posterior part contain rosette shape filiform papillae, in addition to transitional papillae and conical papillae. Two gustatory papillae represented by; small number of fungiform papillae which scattered among the filiform papillae on lingual apex and two lateral regions of the anterior and middle part of tongue, while the three circumvallate papillae on the posterior part were arranged in a triangle form. PMID:23709139

  15. An in-vitro evaluation of the effect of 980 nm diode laser irradiation on intra-canal dentin surface and dentinal tubule openings after biomechanical preparation: Scanning electron microscopic study

    PubMed Central

    Jhingan, Pulkit; Sandhu, Meera; Jindal, Garima; Goel, Deepti; Sachdev, Vinod

    2015-01-01

    Context: Very recently, diode laser has been used for disinfecting the root canals in endodontic treatment and increasing its success rate and longevity utilizing the thermal effect of laser on surrounding tissues. Aims: The aim of this study is to evaluate the effect of 980 nm laser irradiation on intra-canal dentin surface – scanning electron microscopic (SEM) - in-vitro study. Methods: A total of 40 single-rooted freshly extracted permanent teeth were collected. Teeth were sectioned at the cemento-enamel junction using diamond disc. Root canals of all samples were prepared using hand ProTaper, which were randomly assigned into two groups (n = 20 each). Group 1: Receiving no treatment after biomechanical preparation; Group 2: 980 nm diode laser-treated root canals. Teeth were prepared for SEM analysis to check the size of intra-canal dentinal tubule openings. Statistical Analysis Used: Data were analyzed using SPSS V.16 software and compared using Levene's and independent t-test. Results: On statistical analysis, width of intracanal dentinal tubule openings in Group 1 (control) was significantly higher than those observed in Group 2 (diode laser-treated) (P < 0.001). Conclusion: This study showed that the application of 980 nm diode laser on intra-radicular dentin resulted in ultrastructural alterations resulting in melting of dentin. PMID:26097338

  16. In situ conversion of nanostructures from solid to hollow in transmission electron microscopes using electron beam

    NASA Astrophysics Data System (ADS)

    El Mel, Abdel-Aziz; Bittencourt, Carla

    2016-05-01

    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.

  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. PMID:27172892

  18. 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.

  19. 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.

  20. Probing plasmons in three dimensions by combining complementary spectroscopies in a scanning transmission electron microscope.

    PubMed

    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

    2016-04-15

    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. PMID:26934391

  1. Evolutionary developments in x ray and electron energy loss microanalysis instrumentation for the analytical electron microscope

    NASA Astrophysics Data System (ADS)

    Zaluzec, Nester J.

    Developments in instrumentation for both X ray Dispersive and Electron Energy Loss Spectroscopy (XEDS/EELS) over the last ten years have given the experimentalist a greatly enhanced set of analytical tools for characterization. Microanalysts have waited for nearly two decades now in the hope of getting a true analytical microscope and the development of 300 to 400 kV instruments should have allowed us to attain this goal. Unfortunately, this has not generally been the case. While there have been some major improvements in the techniques, there has also been some devolution in the modern AEM (Analytical Electron Microscope). In XEDS, the majority of today's instruments are still plagued by the hole count effect, which was first described in detail over fifteen years ago. The magnitude of this problem can still reach the 20 percent level for medium atomic number species in a conventional off-the-shelf intermediate voltage AEM. This is an absurd situation and the manufacturers should be severely criticized. Part of the blame, however, also rests on the AEM community for not having come up with a universally agreed upon standard test procedure. Fortunately, such a test procedure is in the early stages of refinement. The proposed test specimen consists of an evaporated Cr film approx. 500 to 1000A thick supported upon a 3mm diameter Molybdenum 200 micron aperture.

  2. A light- and electron microscopic analysis of meiotic prophase in female mice.

    PubMed

    Dietrich, A J; Mulder, R J

    1983-01-01

    In the paper we describe meiotic prophase of female mice on successive days of embryonic and early postnatal development. For this purpose we used three different techniques on ovarian material, i.e., Giemsa staining for the light microscopic study of chromatin, silver staining for the light microscopic study of the synaptonemal complex (SC), and agar filtration followed by uranyl acetate staining for the electron microscopic study of the SC. In all types of preparation it was impossible to distinguish leptotene stages, and we conclude that if leptotene really exists, it is of very short duration.--Two types of zygotene stages were found: the "normal" one, resembling zygotene stages in male mice, and a second type that has never been described in males and is characterized by, probably stable, unpaired regions together with totally unpaired axial elements of the SC.--The duration of pachytene was found to be 3-4 days, which is considerably shorter than in males. During early diplotene despiralization of the chromatin and disintegration of the axes of the SC were usually found together with desynapsis.--A considerable variation in distribution of meiotic stages was found between different litters in the same day of gestation. Fetuses in the same litter showed no significant variation. However, the oocytes in an ovary did not pass through meiosis synchronously, with differences up several days. The appearance of chromosomes in a highly contracted state could not be interpreted as a preleptotene condensation stage but probably is a mitotic phenomenon. PMID:6197255

  3. Imaging Vortices in YBa2Cu4O8 using a Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Bowell, Charlotte; Loudon, James; Karpinski, Janusz; Midgley, Paul

    2010-03-01

    When magnetic flux penetrates a Type-II superconductor, it does so in the form of superconducting vortices. The study of these vortices can reveal information about the nature of the superconductivity in the material as well as being important for applications. These vortices can be imaged using a transmission electron microscope (TEM), as the electron beam is deflected by the penetrated magnetic flux. This technique was pioneered by Tonomura et al. [1], using a specially adapted microscope. Recently, it has been demonstrated that vortex imaging is also possible on a commercial TEM [2]. Here we present results on the cuprate superconductor YBa2Cu4O8, in which CuO chains running along the crystal b-direction are thought to become superconducting via a proximity effect with the CuO2 planes. A difficulty encountered with the TEM technique is in producing samples thin enough to be electron transparent. A sample, of size 30 μm x 30 μm x 200 nm, was cut from a bulk YBa2Cu4O8 single crystal using focussed ion beam milling. To look into the influence of the CuO chains, Lorentz imaging was used to investigate the vortex configuration and movement in real time, while holography was employed to study the vortex field profile. [1] Harada et al., Nature 360, 51 - 53 (1992) [2] J. C. Loudon and P. A. Midgley, Ultramicroscopy 109: 700-729 (2009)

  4. 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

  5. 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

  6. rRNA sequence-based scanning electron microscopic detection of bacteria.

    PubMed

    Kenzaka, Takehiko; Ishidoshiro, Ai; Yamaguchi, Nobuyasu; Tani, Katsuji; Nasu, Masao

    2005-09-01

    A new scanning electron microscopic method was developed for gaining both phylogenetic and morphological information about target microbes using in situ hybridization with rRNA-targeted oligonucleotide probes (SEM-ISH). Target cells were hybridized with oligonucleotide probes after gold labeling. Gold enhancement was used for amplification of probe signals from hybridized cells. The hybridized cells released a strong backscatter electron signal due to accumulation of gold atoms inside cells. SEM-ISH was applied to analyze bacterial community composition in freshwater samples, and bacterial cell counts determined by SEM-ISH with rRNA-targeted probes for major phyla within the domain Bacteria were highly correlated to those by fluorescent in situ hybridization (FISH). The bacterial composition on surface of river sediment particles before and after cell dispersion treatment by sonication was successfully revealed by SEM-ISH. Direct enumeration of bacterial cells on the surface of sonicated sediment particles by SEM-ISH demonstrated that members of Cytophaga-Flavobacterium existed tightly on the surface of particles. SEM-ISH allows defining the number and distribution of phylogenetically defined cells adherent to material surfaces, which is difficult in FISH, and it gives new insight into electron microscopic studies of microorganisms in their natural environment. PMID:16151145

  7. Unveiling nanometric plasmons optical properties with advanced electron spectroscopy in the Scanning Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Kociak, Mathieu

    Since the pioneering work of Yamamoto, the use of electron spectroscopy such as Cathodoluminescence (CL) and Electron Energy Loss Spectroscopy (EELS) in a Scanning (Transmission) Electron Microscope (STEM) has considerably helped improving our understanding of the optical properties of metallic nanoparticles. The resemblance of spectroscopic signals from electron and pure optical techniques leads to the intuition that both types of techniques are very close, an idea theoretically discussed by F.J. Garcia de Abajo and coworkers. However, it is also quite intuitive that CL and EELS should be different. For example, EELS helps detecting any sort of modes while CL can only detect radiative ones. On the other hand, even between optical spectroscopy techniques, clear differences such as energy shifts or spectral shapes changes are expected in the case of plasmons. The lack of adapted instrumentation capable of performing combined EELS and CL, as well as theoretical developments allowing to account for the generic difference between EELS and CL and their optical counterparts impeached a comprehensive understanding of plasmons physics with the otherwise amazing electron spectroscopies. In this talk, I will present recent experimental results showing combined EELS and CL spectral mapping of plasmonic properties for nanoparticles with several shapes (triangles, cubes, stars...) and composition (gold, silver, aluminum...). Helped with different theoretical tools, I will try to show how these results can be related to their optical counterparts (extinction, scattering), and what type of physical insights can be gained from these combined measurements. Finally, if time allows, pointing the weaknesses of state-of-the-art CL and EELS (in terms of spectral range and/or spectral resolution), I will present EELS results obtained on highly monochromated electron beams that could cope with these limitations

  8. Fluorination of graphene: a spectroscopic and microscopic study.

    PubMed

    Wang, Bei; Wang, Junjie; Zhu, Jun

    2014-02-25

    Since the advent of graphene, there has been intense interest in exploring the possibility of incorporating fluorinated graphene (FG), an ultrathin insulator, into graphene electronics as barriers, gate dielectrics, and optoelectronic elements. Here we report on the synthesis of FG from single-layer graphene sheets grown by chemical vapor deposition (CVD) using CF4 plasma. We examine its properties systematically via microscopic and spectroscopic probes. Our studies show that, by controlling the conditions of the plasma, FG of varying fluorine coverage can be produced; however, the resulting material contains a mixture of CFx (x = 1-3) bonds. Existing grain boundaries and lattice defects of CVD graphene play an important role in controlling its rate of fluorination and the damage of the sheet. Combining topography and current mapping, we demonstrate that the spatial distribution of fluorine on CVD graphene is highly inhomogeneous, where multilayer islands and structural features such as folds, wrinkles, and ripples are less fluorinated and consequently form a conductive network through which charge transport occurs. It is the properties of this network that manifest in the electrical transport of FG sheets. Our experiments reveal the many challenges of deriving electronics-quality FG from current CVD graphene while at the same time point to the possible solutions and potential of FG in graphene electronics and optoelectronics. PMID:24471932

  9. 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

  10. 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

  11. Novel method for controlled wetting of materials in the environmental scanning electron microscope.

    PubMed

    Jansson, Anna; Nafari, Alexandra; Sanz-Velasco, Anke; Svensson, Krister; Gustafsson, Stefan; Hermansson, Anne-Marie; Olsson, Eva

    2013-02-01

    Environmental scanning electron microscopy has been extensively used for studying the wetting properties of different materials. For some types of investigation, however, the traditional ways of conducting in situ dynamic wetting experiments do not offer sufficient control over the wetting process. Here, we present a novel method for controlled wetting of materials in the environmental scanning electron microscope (ESEM). It offers improved control of the point of interaction between the water and the specimen and renders it more accessible for imaging. It also enables the study of water transport through a material by direct imaging. The method is based on the use of a piezo-driven nanomanipulator to bring a specimen in contact with a water reservoir in the ESEM chamber. The water reservoir is established by local condensation on a Peltier-cooled surface. A fixture was designed to make the experimental setup compatible with the standard Peltier cooling stage of the microscope. The developed technique was successfully applied to individual cellulose fibers, and the absorption and transport of water by individual cellulose fibers were imaged. PMID:23332145

  12. The effect of beam diameter on the electron skirt in a high pressure scanning electron microscope.

    PubMed

    Belkorissat, R; Kadoun, A; Khelifa, B; Mathieu, C

    2004-01-01

    Helium gas and air are commonly used in the high pressure scanning electron microscope (HPSEM). The presence of a gaseous environment in the specimen chamber modifies the electron beam profile. In order to fully understand the beam-gas interaction, we have investigated the beam-diameter effect for two gases (helium and air) by Monte Carlo simulation. In this calculation, we have assumed that the electron beam is Gaussian and we have explored the influence of the nature of the gas at low voltage. When the beam diameter varies between 1 and 100 nm, there is no influence on the beam profile for these two gases. The resolving power of the HPSEM is not affected by the beam-gas interaction. These theoretical results have been compared with experimental images obtained at low voltage under air and helium gases. The variation of image quality at low voltage has confirmed the interest of helium for use in a Field Emission Gun SEM (FEGSEM) in high pressure (or low vacuum) conditions. PMID:15219900

  13. Defect structural evolution in high purity tungsten irradiated with electrons using high voltage electron microscope

    NASA Astrophysics Data System (ADS)

    Fukuzumi, S.; Yoshiie, T.; Satoh, Y.; Xu, Q.; Mori, H.; Kawai, M.

    2005-08-01

    Four types of high purity tungsten were irradiated with 2 MeV electrons to 5 dpa using a high voltage electron microscope, and defect structural evolutions were examined as a function of the irradiation temperature and the concentration of impurity atoms. Three of materials were made by sintering of tungsten powder with purity of 99.999% (5N-W), 99.99% (PF-W) and 99.95% (N-W), and one was a chemical vapor deposited tungsten of 99.9999% (CVD-W) purity. The formation of interstitial type dislocation loops is observed above room temperature by electron irradiation. In sintered tungsten, the number density of loops increases with increasing density of impurity atoms, i.e., N-W > PF-W > 5N-W. The density of loops in CVD-W is relatively high, contrary to its purity. In CVD-W, a heterogeneous formation of loops is observed at above 573 K. Loops are aligned on layers, and no loops are formed between the layers. All four types of specimens have a change in slop of the temperature dependence of loop number density at around 500 K which is caused by impurity atoms. Results of radioactivation analysis and hardness testing are also presented.

  14. 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.

  15. Detection of low contrasted membranes in electron microscope images: statistical contour validation

    NASA Astrophysics Data System (ADS)

    Karathanou, A.; Buessler, J.-L.; Kihl, H.; Urban, J.-P.

    2009-02-01

    Images of biological objects in transmission electron microscopy (TEM) are particularly noisy and low contrasted, making their processing a challenging task to accomplish. During these last years, several software tools were conceived for the automatic or semi-automatic acquisition of TEM images. However, tools for the automatic analysis of these images are still rare. Our study concerns in particular the automatic identification of artificial membranes at medium magnification for the control of an electron microscope. We recently proposed a segmentation strategy in order to detect the regions of interest. In this paper, we introduce a complementary technique to improve contour recognition by a statistical validation algorithm. Our technique explores the profile transition between two objects. A transition is validated if there exists a gradient orthogonal to the contour that is statistically significant.

  16. A new method for measurement of the vitrification rate of earthenware texture by scanning electron microscope.

    PubMed

    Moon, Eun Jung; Kim, Su Kyeong; Han, Min Su; Lee, Eun Woo; Heo, Jun Su; Lee, Han Hyoung

    2013-08-01

    A new method for determining the vitrification rate of pottery depending on the firing temperature was devised using secondary electron images (SEI) of scanning electron microscope (SEM). Several tests were performed to establish the appropriate operating conditions of SEM and reproducibility as well as to examine the applicability of the method. The grayscale values converted from each pixel of SEI were used to determine the vitrification rate of pottery, which in our study were artificially fired specimens composed of three types of clay. A comparison between the vitrification rate value and appearance temperature of minerals shows that mullite formation starts at 1,100°C, during which the vitrification rate rapidly increases by over 10%. In consequence, the result presented here demonstrates that the new method can be applied to estimate the firing temperature of pottery. PMID:23920198

  17. 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

  18. 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.

  19. 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...

  20. Investigation of Sterilization Effect by various Gas Plasmas and Electron Microscopic Observation of Bacteria

    NASA Astrophysics Data System (ADS)

    Sasaki, Yota; Takamatsu, Toshihiro; Uehara, Kodai; Oshita, Takaya; Miyahara, Hidekazu; Okino, Akitoshi; Ikeda, Keiko; Matsumura, Yuriko; Iwasawa, Atsuo; Kohno, Masahiro

    2014-10-01

    Atmospheric non-thermal plasmas have attracted attention as a new sterilization method. It is considered that factor of plasma sterilization are mainly reactive oxygen species (ROS). However, the sterilization mechanism hasn't been investigated in detail because conventional plasma sources have a limitation in usable gas species and lack variety of ROS. So we developed multi-gas plasma jet which can generate various gas plasmas. In this study, investigation of sterilization effect by various gas plasmas and electron microscopic observation of bacteria were performed. Oxygen, nitrogen, carbon dioxide, argon and air were used as plasma gas. To investigate gas-species dependence of sterilization effect, S.aureus was treated. As a result, nitrogen plasma and carbon dioxide plasma were effective for sterilization. To investigate sterilization mechanism, the surface of S.aureus was observed by scanning electron microscope. As a result, dimples were observed on the surface after irradiation of nitrogen plasma, but no change observed in the case of carbon dioxide plasma. These results suggest that bactericidal mechanism of nitrogen and carbon dioxide plasma should be different. In the presentation, Measurement result of ROS will be reported.

  1. 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

  2. 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

  3. [Electron microscopy study of artificial vitreous gel].

    PubMed

    Ehgartner, E M; Schmut, O; Hofmann, H

    1986-04-01

    Artificial gels prepared from Cu2+-ions and hyaluronic acid were studied in the electron microscope and compared with the native vitreous body. Additionally, the authors attempted to produce transparent gels from the native constituents of the vitreous body, namely collagen and hyaluronic acid. Mixing of solutions of these constituents formed no gels but white precipitates. The ultrastructure of these precipitates was also studied in the electron microscope. PMID:3723971

  4. Intercomparison of lateral scales of scanning electron microscopes and atomic force microscopes in research institutes in Northern Europe

    NASA Astrophysics Data System (ADS)

    Seppä, Jeremias; Korpelainen, Virpi; Bergstrand, Sten; Karlsson, Helge; Lillepea, Lauri; Lassila, Antti

    2014-04-01

    An intercomparison of lateral scales of scanning electron microscopes (SEM) and atomic force microscopes (AFM) in various research laboratories in Northern Europe was organized by the local national metrology institutes. In this paper are presented the results of the comparison, with also an example uncertainty budget for AFM grating pitch measurement. Grating samples (1D) were circulated among the participating laboratories. The participating laboratories were also asked about the calibration of their instruments. The accuracy of the uncertainty estimates seemed to vary largely between the laboratories, and for some laboratories the appropriateness of the calibration procedures could be considered. Several institutes (60% of all results in terms of En value) also had good comprehension of their measurement capability. The average difference from reference value was 6.7 and 10.0 nm for calibrated instruments and 20.6 and 39.9 nm for uncalibrated instruments for 300 nm and 700 nm gratings, respectively. The correlation of the results for both nominally 300 and 700 nm gratings shows that a simple scale factor calibration would have corrected a large part of the deviations from the reference values.

  5. Electron Microscope and Autoradiographic Study of Ultrastructural Aspects of Competence and Deoxyribonucleic Acid Absorption in Bacillus subtilis: Ultrastructure of Competent and Noncompetent Cells and Cellular Changes During Development of Competence

    PubMed Central

    Vermeulen, C. A.; Venema, G.

    1974-01-01

    By means of electron microscope autoradiography of component cultures of Bacillus subtilis exposed to [3H]thymidine-labeled transforming deoxyribonucleic acid competent and noncompetent cells can be distinguished. Competence is not limited to a specific phase of the cell division cycle. With serial section electron microscopy of competent and noncompetent cells, two types of mesosomal structures are observed: mesosomes connected to the plasma membrane only (plasma membrane mesosomes) and mesosomes which are additionally connected to the nuclear bodies (nuclear mesosomes). The two types show different cellular distributions. Especially the number of nuclear mesosomes is higher in competent than in noncompetent cells. This, and the observation that the increase and decrease of competence is correlated with both the number of cells carrying nuclear mesosomes and the number of nuclear mesosomes per cell, suggests that mesosomes are involved in the acquisition of competence. PMID:4208130

  6. 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.

  7. Electron microscopic observations of hydrogen implantation in ilmenites

    NASA Technical Reports Server (NTRS)

    Blanford, G. E.

    1983-01-01

    Hydrogen ion beams were found to form submicrometer, bumpy textures on the surface of ilmenite grains. From this effect, it is believed that similar bumpy textures seen on lunar ilmenite, pyroxene, and olivine grains are likely to be caused by solar wind irradiation. As a consequence, the concentration of bumpy textured grains may be a useful index of surface maturity for lunar soils. An attempt was made to search for grains with these bumpy textures in interplanetary dust and lunar and meteoritic regolith breccias in order to obtain information about the duration of their exposure to the solar wind. Solar wind irradiation was simulated on natural, terrestrial ilmenite. Hydrogen ion beams were directed at small grains and polished sections which were then examined by electron microscopy.

  8. 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.

  9. Endogenous pneumoconiosis: Analytical scanning electron microscopic analysis of a case.

    PubMed

    Galeotti, Jonathan; Sporn, Thomas A; Ingram, Peter; Wahidi, Momen M; Roggli, Victor L

    2016-01-01

    Pneumoconiosis is often considered a disease of the lung initiated by exposure to dust or other airborne particles, resulting in injury to the lungs. The term "endogenous pneumoconiosis" has been used in the literature to describe the deposition of compounds on the elastic fibers of the lung, usually in the setting of cardiac failure. In the case we present here, the patient aspirated a foreign body resulting in damage to the lung tissue and subsequent deposition of endogenous compounds on the elastic fibers of the pulmonary parenchyma and vasculature. We determined the composition of this mineral and mapped the distribution of elements using a combination of backscattered electron microscopy and energy dispersive spectrometry. PMID:27281119

  10. Approaches for ultrafast imaging of transient materials processes in the transmission electron microscope.

    PubMed

    LaGrange, Thomas; Reed, Bryan W; Santala, Melissa K; McKeown, Joseph T; Kulovits, Andreas; Wiezorek, Jörg M K; Nikolova, Liliya; Rosei, Federico; Siwick, Bradely J; Campbell, Geoffrey H

    2012-11-01

    The growing field of ultrafast materials science, aimed at exploring short-lived transient processes in materials on the microsecond to femtosecond timescales, has spawned the development of time-resolved, in situ techniques in electron microscopy capable of capturing these events. This article gives a brief overview of two principal approaches that have emerged in the past decade: the stroboscopic ultrafast electron microscope and the nanosecond-time-resolved single-shot instrument. The high time resolution is garnered through the use of advanced pulsed laser systems and a pump-probe experimental platforms using laser-driven photoemission processes to generate time-correlated electron probe pulses synchronized with laser-driven events in the specimen. Each technique has its advantages and limitations and thus is complementary in terms of the materials systems and processes that they can investigate. The stroboscopic approach can achieve atomic resolution and sub-picosecond time resolution for capturing transient events, though it is limited to highly repeatable (>10(6) cycles) materials processes, e.g., optically driven electronic phase transitions that must reset to the material's ground state within the repetition rate of the femtosecond laser. The single-shot approach can explore irreversible events in materials, but the spatial resolution is limited by electron source brightness and electron-electron interactions at nanosecond temporal resolutions and higher. The first part of the article will explain basic operating principles of the stroboscopic approach and briefly review recent applications of this technique. As the authors have pursued the development of the single-shot approach, the latter part of the review discusses its instrumentation design in detail and presents examples of materials science studies and the near-term instrumentation developments of this technique. PMID:22595460

  11. 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

  12. 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.

  13. 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.

  14. Electron magnetic chiral dichroism in CrO2 thin films using monochromatic probe illumination in a transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Loukya, B.; Zhang, X.; Gupta, A.; Datta, R.

    2012-11-01

    Electron magnetic chiral dichroism (EMCD) has been studied in CrO2 thin films (with (100) and (110) growth orientations on TiO2 substrates) using a gun monochromator in an aberration corrected transmission electron microscope operating at 300 kV. Excellent signal-to-noise ratio is obtained at spatial resolution ˜10 nm using a monochromatic probe as compared to conventional parallel illumination, large area convergent beam electron diffraction and scanning transmission electron microscopy techniques of EMCD. Relatively rapid exposure using mono probe illumination enables collection of EMCD spectra in total of 8-9 min in energy filtered imaging mode for a given Cr L2,3 energy scan (energy range ˜35 eV). We compared the EMCD signal obtained by extracting the Cr L2,3 spectra under three beam diffraction geometry of two different reciprocal vectors (namely g=110 and 200) and found that the g=200 vector enables acquisition of excellent EMCD signal from relatively thicker specimen area due to the associated larger extinction distance. Orbital to spin moment ratio has been calculated using EMCD sum rules for 3d elements and dichroic spectral features associated with CrO2 are compared and discussed with XMCD theoretical spectra.

  15. Fabrication and characterization of solid-state nanopores using a field emission scanning electron microscope

    SciTech Connect

    Chang Hung; Iqbal, Samir M.; Stach, Eric A.; King, Alexander H.; Zaluzec, Nestor J.; Bashir, Rashid

    2006-03-06

    The fabrication of solid-state nanopores using the electron beam of a transmission electron microscope (TEM) has been reported in the past. Here, we report a similar method to fabricate solid-state nanopores using the electron source of a conventional field-emission scanning electron microscope (FESEM) instead. Micromachining was used to create initial pore diameters between 50 nm and 200 nm, and controlled pore shrinking to sub 10 nm diameters was performed subsequently during in situ processing in the FESEM. Noticeably, different shrinking behavior was observed when using irradiation from the electron source of the FESEM than the TEM. Unlike previous reports of TEM mediated pore shrinkage, the mechanism of pore shrinkage when using the FESEM could be a result of surface defects generated by radiolysis and subsequent motion of silicon atoms to the pore periphery.

  16. 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.

  17. Scanning Capacitace Microscope/Atomic Force Microscope/Scanning Tunneling Microscope Study of Ion-Implanted Silicon Surfaces

    NASA Astrophysics Data System (ADS)

    Tomiye, Hideto; Kawami, Hiroshi; Izawa, Michiyoshi; Yoshimura, Masamichi; Yao, Takafumi

    1995-06-01

    We have investigated the local electrical properties of ion-implanted Si using a combined scanning capacitance microscope (SCaM)/atomic force microscope (AFM)/scanning tunneling microscope (STM) with special attention paid to the effect of annealing. The STM image shows that the as-implanted area is insulating, while the unimplanted area is conductive, in an unannealed sample. Both STM and SCaM images clearly indicate that the implanted area is conductive with n-type behavior after annealing. However, the unimplanted area did not show p-type behavior but slightly n-type behavior due to the diffusion of P impurities during annealing.

  18. 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. PMID:19204999

  19. EVALUATING AND OPTIMIZING ELECTRON MICROSCOPE METHODS FOR CHARACTERIZING AIRBORNE ASBESTOS

    EPA Science Inventory

    Evaluation of EM methods for measuring airborne asbestos fiber concentrations and size distributions was carried out by studying a large number of variables and subprocedures in a five-phase program using elaborate statistically designed experiments. Observations were analyzed by...

  20. 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

  1. Mite Biodiversity Under the Low Temperature Scanning Electron Microscope

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To date, more than 55,000 mite species have been described and only a few of them have been studied. Some mites are adapted to live deep in soil, others in fresh or sea water, some are on plants, algae, fungi or animals, and others are able to survive in both extreme cold and hot temperatures. The...

  2. Scanning Electron Microscope Observation of Carbon Nanotubes with Room Temperature Ionic Liquids: Effect of Their Hydrophilicities.

    PubMed

    Hyono, Atsushi; Abe, Shigeaki; Kawai, Koji; Yonezawa, Tetsu

    2015-11-01

    In this study, we succeeded in acquiring scanning electron microscope (SEM) images of carbon nanotube (CNT) derivatives with different surface properties based on an electro-conductive pretreatment using a room temperature ionic liquid (IL). The quality of the obtained SEM images depended on their surface properties and the hydrophilicities of IL used. When the hydrophilicities of both the sample surface and the IL were close, the obtained SEM images had a high resolution. In contrast, SEM imges of samples pretreated with an IL, which had different hydrophilicities from the sample, was observed with low resolution and low quality. This result suggests that the relationship between both hydrophilicities is the dominant factor for this visualization method. PMID:26726681

  3. Observations of Carbon Nanotube Oxidation in an Aberration-Corrected, Environmental Transmission Electron Microscope

    PubMed Central

    Koh, Ai Leen; Gidcumb, Emily; Zhou, Otto; Sinclair, Robert

    2013-01-01

    We report the first direct study on the oxidation of carbon nanotubes at the resolution of an aberration-corrected environmental transmission electron microscope (ETEM), as we locate and identify changes in the same nanotubes as they undergo oxidation at increasing temperatures in-situ in the ETEM. Contrary to earlier reports that CNT oxidation initiates at the end of the tube and proceeds along its length, our findings show that only the outside graphene layer is being removed and on occasion, the interior inner wall is oxidized, presumably due to oxygen infiltrating into the hollow nanotube through an open end or breaks in the tube. We believe that this work provides the foundation for much scientific understanding of the mechanism underlying the nanotube oxidation process, as well as guidelines to manipulate their structure or prevent their oxidation. PMID:23360330

  4. 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.

  5. Determination of the sequence of intersecting lines using Focused Ion Beam/Scanning Electron Microscope.

    PubMed

    Kim, Jiye; Kim, MinJung; An, JinWook; Kim, Yunje

    2016-05-01

    The aim of this study was to verify that the combination of focused ion beam (FIB) and scanning electron microscope/energy-dispersive X-ray (SEM/EDX) could be applied to determine the sequence of line crossings. The samples were transferred into FIB/SEM for FIB milling and an imaging operation. EDX was able to explore the chemical components and the corresponding elemental distribution in the intersection. The technique was successful in determining the sequence of heterogeneous line intersections produced using gel pens and red sealing ink with highest success rate (100% correctness). These observations show that the FIB/SEM was the appropriate instrument for an overall examination of document. PMID:27122423

  6. 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.

  7. 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

  8. 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. PMID:23026379

  9. 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

  10. Scanning electron microscope findings of the lased implant surface

    NASA Astrophysics Data System (ADS)

    Tsuda, Tadamasu; Matsumoto, Koukichi

    1995-04-01

    Ever since Geusic developed the Nd:YAG laser in 1965, there have been numerous fundamental and clinical studies conducted, and reports on its clinical applications in many fields of dentistry, including its potential use for soft tissues to hard tissues. It seems especially effective for these applications when conducting the secondary operations and is actually being clinically applied. Despite the relatively satisfactory results obtained in incising or vaporizing, there have been very few reports concerning the morphological changes on implant structures resulting from laser irradiation. In this report, we would like to consider the extent to which it may be possible to apply Nd:YAG lasers for treating implants. We will discuss the results of the fundamental tests we have conducted together with cases of actual clinical application.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. X-Ray Microanalysis in the Variable Pressure (Environmental) Scanning Electron Microscope

    PubMed Central

    Newbury, Dale E.

    2002-01-01

    Electron-excited x-ray microanalysis performed in the variable pressure and environmental scanning electron microscopes is subject to additional artifacts beyond those encountered in the conventional scanning electron microscope. Gas scattering leads to direct contributions to the spectrum from the environmental gas, as well as remote generation of x rays by electrons scattered out of the focussed beam. The analyst can exert some degree of control over these artifacts, but depending on the exact situation, spurious elements can appear at the trace (< 0.01 mass fraction), minor (0.01 mass fraction to 0.1 mass fraction), or even major (> 0.1 mass fraction) levels. Dispersed particle samples give the least compromised results, while fine scale microstructures are the most severely compromised. Procedures to optimize the situation based upon specimen preparation as well as spectral processing are described. PMID:27446754

  16. 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 ...

  17. ELECTRON MICROSCOPE MEASUREMENT OF AIRBORNE ASBESTOS CONCENTRATIONS - A PROVISIONAL METHODOLOGY MANUAL

    EPA Science Inventory

    This manual describes a provisional optimum electron microscope (EM) procedure for measuring the concentration of asbestos in air samples. The main features of the method include depositing an air sample on a polycarbonate membrane filter, examining an EM grid specimen in a trans...

  18. ELECTRON MICROSCOPE MEASUREMENT OF AIRBORNE ASBESTOS CONCENTRATIONS. A PROVISIONAL METHODOLOGY MANUAL

    EPA Science Inventory

    This manual describes a provisional optimum electron microscope (EM) procedure for measuring the concentration of asbestos in air samples. The main features of the method include depositing an air sample on a polycarbonate membrane filter, examining an EM grid specimen in a trans...

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. An ultrafast electron microscope gun driven by two-photon photoemission from a nanotip cathode

    NASA Astrophysics Data System (ADS)

    Bormann, Reiner; Strauch, Stefanie; Schäfer, Sascha; Ropers, Claus

    2015-11-01

    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.

  4. 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

  5. Naturally weathered feldspar surfaces in the Navajo Sandstone aquifer, Black Mesa, Arizona: Electron microscopic characterization

    NASA Astrophysics Data System (ADS)

    Zhu, Chen; Veblen, David R.; Blum, Alex E.; Chipera, Stephen J.

    2006-09-01

    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 μm 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 ˜10 5 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

  6. 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.

  7. 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.

  8. 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. PMID:27285177

  9. 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

  10. 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

  11. 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.

  12. Immuno-Electron Microscopy and Electron Microscopic In Situ Hybridization for Visualizing piRNA Biogenesis Bodies in Drosophila Ovaries.

    PubMed

    Shibata, Shinsuke; Murota, Yukiko; Nishimoto, Yoshinori; Yoshimura, Mana; Nagai, Toshihiro; Okano, Hideyuki; Siomi, Mikiko C

    2015-01-01

    Immuno-electron microscopy and electron microscopic in situ hybridization are powerful tools to identify the precise subcellular localization of specific proteins and RNAs at the ultramicroscopic level. Here we describe detailed procedures for how to detect the precise location of a specific target labeled with both fluorescence and gold particles. Although they have been developed for the analysis of Drosophila ovarian somatic cells, these techniques are suitable for a wide range of biological applications including human, primate, and rodent analysis. PMID:26324437

  13. 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

  14. 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.

  15. Biochemical, histopathological, and transmission electron microscopic ultrastructural changes in mice after exposure to silver nanoparticles.

    PubMed

    Ansari, Mohammad Azam; Khan, Haris M; Khan, Aijaz A; Alzohairy, Mohammad A; Waseem, Mohammad; Ahmad, Mohammad Kaleem; Mahdi, Abbas Ali

    2016-08-01

    Four-week-old mice, weighing about 25-35 g were divided into five groups (8 mice in each group): vehicle control, low- (0.5 g/kg), middle- (1 g/kg), high- (3 g/kg), and exceptionally high-dose (5 g/kg). After first and second weeks of intraperitoneal exposure to AgNPs, biochemical, histopathological, and electron microscopic ultrastructural changes were investigated. No significant changes were observed in SGOT and ALP levels after first week of exposure, while the level of SGPT significantly increased (p < 0.05) in 2nd week treated mice, indicating that inflammatory of liver might be induced by high-dose (3 and 5 g/kg) of AgNPs. No obvious changes were observed for UA and BUN in all groups of treated mice. However, significant (p < 0.05) decrease in CR level was noticed in all groups of treated mice only at high-dose (3 and 5 g/kg). No remarkable changes in lipid profile were observed. Light microscopic histopathological investigation shows that first week treatment had not perceptible effect on the cytoarchitecture on liver, kidney, and spleen; while, second week treatment had only sporadic mild effects on these organs. However, no ultrastructural electron microscopic changes were observed in liver, kidney, and spleen of mice treated with 0.5, 1, and 3 g/kg of AgNPs when sacrificed on first and second week; while, exceptionally high-dose (5 g/kg) of AgNPs resulted in slight nuclear chromatin condensation and irregularities in nuclear membrane. The results suggested that AgNPs could be well tolerated in mice when given intraperitoneally and no death has been found during the experiment in any groups of treated mice. Interestingly, significant (<0.05) decrease in glucose levels in all experiment group is suggestive of curious hypoglycemic role of AgNPs warranting further study to explore its possible therapeutic potential in hyperglycemic conditions as well as its mechanism of action at molecular level. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31

  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. 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.

  18. 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

  19. Study of factors affecting the appearance of colors under microscopes

    NASA Astrophysics Data System (ADS)

    Zakizadeh, Roshanak; Martinez-Garcia, Juan; Raja, Kiran B.; Siakidis, Christos

    2013-11-01

    The variation of colors in microscopy systems can be quite critical for some users. To address this problem, a study is conducted to analyze how different factors such as size of the sample, intensity of the microscope's light source and the characteristics of the material like chroma and saturation can affect the color appearance through the eyepiece of the microscope. To study the changes in colors considering these factors, the spectral reflectance of 24 colors of GretagMacbeth Classic ColorChecker® and Mini ColorChecker® which are placed under a Nikon ECLIPSE MA200 microscope®2 using dark filed and bright field illuminations which result in different intensity levels, is measured using a spectroradiometer®3 which was placed in front of the eyepiece of the microscope. The results are compared with the original data from N. Ohta1. The evaluation is done by observing the shift in colors in the CIE 1931 Chromaticity Diagram and the CIELAB space, also by applying a wide set of color-difference formulas, namely: CIELAB, CMC, BFD, CIE94, CIEDE2000, DIN99d and DIN99b. Furthermore, to emphasize on the color regions in which the highest difference is observed, the authors have obtained the results from another microscope; Olympus SZX10®4, which in this case the measurement is done by mounting the spectroradiometer to the camera port of the microscope. The experiment leads to some interesting results, among which is the consistency in the highest difference observed considering different factors or how the change in saturation of the samples of the same hue can affect the results.

  20. 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.

  1. 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.

  2. 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. PMID:2391565

  3. Near-atomic resolution reconstructions using a mid-range electron microscope operated at 200 kV

    PubMed Central

    Campbell, Melody G.; Kearney, Bradley M.; Cheng, Anchi; Potter, Clinton S.; Johnson, John E.; Carragher, Bridget

    2014-01-01

    SUMMARY A new era has begun for single particle cryo-electron microscopy (cryoEM) which can now compete with X-ray crystallography for determination of protein structures. The development of direct detectors constitutes a revolution that has led to a wave of near-atomic resolution cryoEM reconstructions. However, regardless of the sample studied, virtually all high-resolution reconstructions reported to date have been achieved using high-end microscopes. We demonstrate that the new generation of direct detectors coupled to a widely used mid-range electron microscope also enables obtaining cryoEM maps of sufficient quality for de novo modeling of protein structures of different sizes and symmetries. We provide an outline of the strategy used to achieve a 3.7 Å resolution reconstruction of Nudaurelia capensis ω virus and a 4.2 Å resolution reconstruction of the Thermoplasma acidophilum T20S proteasome. PMID:25278130

  4. Conductive resins improve charging and resolution of acquired images in electron microscopic volume imaging.

    PubMed

    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

  5. 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

  6. Isolation, electron microscopic imaging, and 3-D visualization of native cardiac thin myofilaments.

    PubMed

    Spiess, M; Steinmetz, M O; Mandinova, A; Wolpensinger, B; Aebi, U; Atar, D

    1999-06-15

    An increasing number of cardiac diseases are currently pinpointed to reside at the level of the thin myofilaments (e.g., cardiomyopathies, reperfusion injury). Hence the aim of our study was to develop a new method for the isolation of mammalian thin myofilaments suitable for subsequent high-resolution electron microscopic imaging. Native cardiac thin myofilaments were extracted from glycerinated porcine myocardial tissue in the presence of protease inhibitors. Separation of thick and thin myofilaments was achieved by addition of ATP and several centrifugation steps. Negative staining and subsequent conventional and scanning transmission electron microscopy (STEM) of thin myofilaments permitted visualization of molecular details; unlike conventional preparations of thin myofilaments, our method reveals the F-actin moiety and allows direct recognition of thin myofilament-associated porcine cardiac troponin complexes. They appear as "bulges" at regular intervals of approximately 36 nm along the actin filaments. Protein analysis using SDS-polyacrylamide gel electrophoresis revealed that only approximately 20% troponin I was lost during the isolation procedure. In a further step, 3-D helical reconstructions were calculated using STEM dark-field images. These 3-D reconstructions will allow further characterization of molecular details, and they will be useful for directly visualizing molecular alterations related to diseased cardiac thin myofilaments (e.g., reperfusion injury, alterations of Ca2+-mediated tropomyosin switch). PMID:10388621

  7. 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

  8. 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.

  9. Microscopic Study of Surface Microtopographic Characteristics of Dental Implants

    PubMed Central

    Sezin, M.; Croharé, L.; Ibañez, J.C.

    2016-01-01

    Objective: To determine and compare the micro topographic characteristics of dental implants submitted to different surface treatments, using scanning electron microscopy (SEM). Materials and Methods: Implants were divided into 7 groups of 3 specimens each, according to the surface treatment used: group 1: Osseotite, BIOMET 3i; group 2: SLA surface, Institut Straumann AG; group 3: Oxalife surface, Tree-Oss implant; group 4: B&W implant surface; group 5: Q-implant surface; group 6: ML implant surface; group 7: RBM surface, Rosterdent implant. The surfaces were examined under SEM (Carl Zeiss FE-SEM-SIGMA). Image Proplus software was used to determine the number and mean diameter of pores per area unit (mm). The data obtained were analyzed with the Mann-Whitney test. A confocal laser microscope (LEXT-OLS4100 Olympus) was used to conduct the comparative study of surface roughness (Ra). Data were analyzed using Tukey's HSD test. Results: The largest average pore diameter calculated in microns was found in group 5 (3.45 µm+/-1.91) while the smallest in group 7 (1.47µm+/-1.29). Significant differences were observed among each one of the groups studied (p<0.05). The largest number of pores/mm2 was found in group 2 (229343) and the smallest number in group 4 (10937). Group 2 showed significant differences regarding the other groups (p<0.05). The greatest roughness (Ra) was observed in group 2 (0.975µm+/-0.115) and the smallest in group 4 (0.304µm+/-0.063). Group 2 was significantly different from the other groups (p<0.05). Conclusion: The micro topography observed in the different groups presented dissimilar and specific features, depending on the chemical treatment used for the surfaces.. PMID:27335615

  10. 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.

  11. Structural relations between collagen and mineral in bone as determined by high voltage electron microscopic tomography

    NASA Technical Reports Server (NTRS)

    Landis, W. J.; Hodgens, K. J.; Arena, J.; Song, M. J.; McEwen, B. F.

    1996-01-01

    Aspects of the ultrastructural interaction between collagen and mineral crystals in embryonic chick bone have been examined by the novel technique of high voltage electron microscopic tomography to obtain three-dimensional information concerning extracellular calcification in this tissue. Newly mineralizing osteoid along periosteal surfaces of mid-diaphyseal regions from normal chick tibiae was embedded, cut into 0.25 microns thick sections, and documented at 1.0 MV in the Albany AEI-EM7 high voltage electron microscope. The areas of the tissue studied contained electron dense mineral crystals associated with collagen fibrils, some marked by crystals disposed along their cylindrically shaped lengths. Tomographic reconstructions of one site with two mineralizing fibrils were computed from a 5 degrees tilt series of micrographs over a +/- 60 degrees range. Reconstructions showed that the mineral crystals were platelets of irregular shape. Their sizes were variable, measured here up to 80 x 30 x 8 nm in length, width, and thickness, respectively. The longest crystal dimension, corresponding to the c-axis crystallographically, was generally parallel to the collagen fibril long axis. Individual crystals were oriented parallel to one another in each fibril examined. They were also parallel in the neighboring but apparently spatially separate fibrils. Crystals were periodically (approximately 67 nm repeat distance) arranged along the fibrils and their location appeared to correspond to collagen hole and overlap zones defined by geometrical imaging techniques. The crystals appeared to be continuously distributed along a fibril, their size and number increasing in a tapered fashion from a relatively narrow tip containing smaller and infrequent crystals to wider regions having more densely packed and larger crystals. Defined for the first time by direct visual 3D imaging, these data describe the size, shape, location, orientation, and development of early crystals in normal

  12. 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.

  13. Electron microscopic stereological study of collagen fibrils in bovine articular cartilage: volume and surface densities are best obtained indirectly (from length densities and diameters) using isotropic uniform random sampling

    PubMed Central

    LÅNGSJÖ, TEEMU K.; HYTTINEN, MIKA; PELTTARI, ALPO; KIRALY, KARI; AROKOSKI, JARI; HELMINEN, HEIKKI J.

    1999-01-01

    utilisation of these estimates, is here regarded as representing a ‘gold standard’. The sensitivity of these 3 methods was also tested with cartilage from an in vitro loading experiment which caused tissue compression. In the superficial zone of articular cartilage Vv and Sv of collagen fibrils increased (P<0.05). This difference in the stereological estimates was only detected by the indirect IUR estimation but not by the direct VS or direct IUR methods. This indicated that the indirect IUR estimation was more sensitive than the direct VS or direct IUR estimations. On the basis of these observations, the indirect zonal IUR estimation can be regarded as the technique of choice in the electron microscopic stereology of cartilage collagen. PMID:10529063

  14. Scanning Electron Microscope Calibration Using a Multi-Image Non-Linear Minimization Process

    NASA Astrophysics Data System (ADS)

    Cui, Le; Marchand, Éric

    2015-04-01

    A scanning electron microscope (SEM) calibrating approach based on non-linear minimization procedure is presented in this article. A part of this article has been published in IEEE International Conference on Robotics and Automation (ICRA), 2014. . Both the intrinsic parameters and the extrinsic parameters estimations are achieved simultaneously by minimizing the registration error. The proposed approach considers multi-images of a multi-scale calibration pattern view from different positions and orientations. Since the projection geometry of the scanning electron microscope is different from that of a classical optical sensor, the perspective projection model and the parallel projection model are considered and compared with distortion models. Experiments are realized by varying the position and the orientation of a multi-scale chessboard calibration pattern from 300× to 10,000×. The experimental results show the efficiency and the accuracy of this approach.

  15. In-situ nanoindentation specimen holder for a high-voltage transmission electron microscope

    SciTech Connect

    Dahmen; U; Wall, M A

    1998-09-17

    This report describes the design, construction, and testing of a nanoindentation specimen holder used for dynamic observation of subsurface microstructure evolution under an indenter tip, while viewing in cross-section in a high-voltage transmission electron microscope (TEM). It also discusses the initial experimental results from in-situ indentation of Si samples in the TEM to demonstrate the capability of this new nanoindentation specimen holder, which uses three-axis position control of a diamond indenter in combination with micromachined specimens. Additionally, the sample design techniques developed for these procedures may eliminate the need for TEM specimen preparation in future ex-situ nanoindentation experiments and for sample preparation for characterizing these experiments in the electron microscope.

  16. Low thermal power electron beam annealing of scanning tunneling microscope tips

    NASA Astrophysics Data System (ADS)

    Scholz, R.; Agne, M.; Breitenstein, O.; Jenniches, H.

    1997-08-01

    An add-on unit was developed that allows the cleaning of scanning tunneling microscope tips by electron beam annealing even if they cannot be disconnected from the piezo scanner in situ. The whole scanner tip combination, which is attached to a linear motion stage, is subjected to a pulsed annealing treatment. The heat impact is focused on the outermost tip by sticking the tip through a hole in a grounded Mo screening plate with the cathode mounted on the opposite side. Tungsten tips attached to the scanner of the Omicron ultrahigh vacuum Multiscan Lab were annealed to achieve atomic resolution of ultrahigh vacuum cleaved GaAs (110) faces. A highly doped superlattice package grown on semi-insulating GaAs was also able to be investigated on the cleaved (110) face due to the ability of exact tip positioning with a scanning electron microscope.

  17. Depth Sectioning with the Aberration-Corrected Scanning Transmission Electron Microscope

    SciTech Connect

    Borisevich, Albina Y; Lupini, Andrew R; Pennycook, Stephen J

    2006-01-01

    The ability to correct the aberrations of the probe-forming lens in the scanning transmission electron microscope provides not only a significant improvement in transverse resolution but in addition brings depth resolution at the nanometer scale. Aberration correction therefore opens up the possibility of 3D imaging by optical sectioning. Here we develop a definition for the depth resolution for scanning transmission electron microscope depth sectioning and present initial results from this method. Objects such as catalytic metal clusters and single atoms on various support materials are imaged in three dimensions with a resolution of several nanometers. Effective focal depth is determined by statistical analysis and the contributing factors are discussed. Finally, current challenges and future capabilities available through new instruments are discussed.

  18. LIGHT MICROSCOPICAL AND ELECTRON MICROSCOPICAL COMPARISONS OF NORMAL HEPATOCYTES OF WELL-DIFFERENTIATED HEPATOCELLULAR CARCINOMAS IN A TELEOST FISH

    EPA Science Inventory

    Well-differentiated hepatocellular carcinomas (HCC's) induced in the sheepshead minnow (Cyprinodon variagatus) with N-nitrosodiethylamine, permitted light microscopical and ultrastructural comparisons of normal hepatocytes and adjacent HCC cells. ormal hepatocytes contained typic...

  19. [Electron-microscopic autoradiography of RNA synthesis in the myocardium after damage to it].

    PubMed

    Galankin, V N; Pal'tsyn, A A; Badikova, A K

    1977-06-01

    Thermic burn of the wall of the left cardiac ventricle was inflicted to new born rats. Twenty-four hours after the injury the RNA synthesis of the myocardial cells remote from the site of burn were investigated by electron-microscopic autoradiography. Tissue samples were fixed 2 and 6 hours after the 3H-uridine injections. As compared with the control, experimental animals displayed a reduction of silver grains density over the nucleus and the cytoplasm of cardiomyocytes. PMID:884310

  20. A sample holder with integrated laser optics for an ELMITEC photoemission electron microscope

    SciTech Connect

    Gierster, L.; Pape, L.; Ünal, A. A.; Kronast, F.

    2015-02-15

    We present a new sample holder compatible with ELMITEC Photoemission Electron Microscopes (PEEMs) containing an optical lens and a mirror. With the integrated optical elements, a laser beam is focused from the back side of the sample at normal incidence, yielding a minimum spot size of about 1 μm. This opens up new possibilities for local laser excitations in PEEM experiments such as imaging all-optical magnetization switching at a small length scale.

  1. Ultra-structural hair alterations of drug abusers: a scanning electron microscopic investigation.

    PubMed

    Turkmenoglu, Fatma Pinar; Kasirga, Ugur Baran; Celik, Hakan Hamdi

    2015-01-01

    As drug abuse carries a societal stigma, patients do not often report their history of drug abuse to the healthcare providers. However, drug abuse is highly co-morbid with a host of other health problems such as psychiatric disorders and skin diseases, and majority of individuals with drug use disorders seek treatment in the first place for other problems. Therefore, it is very important for physicians to be aware of clinical signs and symptoms of drug use. Recently diagnostic value of dermatologic tissue alterations associated with drug abuse has become a very particular interest because skin changes were reported to be the earliest noticeable consequence of drug abuse prompting earlier intervention and treatment. Although hair is an annex of skin, alterations on hair structure due to drug use have not been demonstrated. This study represents the first report on ultra-structural hair alterations of drug abusers. We have investigated ultra-structure of the hair samples obtained from 6 cocaine, 6 heroin, 7 cannabis and 4 lysergic acid diethylamide (LSD) abusers by scanning electron microscope (SEM). SEM analysis of hair samples gave us drug-specific discriminating alterations. We suggest that results of this study will make a noteworthy contribution to cutaneous alterations associated with drug abuse which are regarded as the earliest clinical manifestations, and this SEM approach is a very specific and effective tool in the detection of abuse of respective drugs, leading early treatment. PMID:26309532

  2. Ultra-structural hair alterations of drug abusers: a scanning electron microscopic investigation

    PubMed Central

    Turkmenoglu, Fatma Pinar; Kasirga, Ugur Baran; Celik, Hakan Hamdi

    2015-01-01

    As drug abuse carries a societal stigma, patients do not often report their history of drug abuse to the healthcare providers. However, drug abuse is highly co-morbid with a host of other health problems such as psychiatric disorders and skin diseases, and majority of individuals with drug use disorders seek treatment in the first place for other problems. Therefore, it is very important for physicians to be aware of clinical signs and symptoms of drug use. Recently diagnostic value of dermatologic tissue alterations associated with drug abuse has become a very particular interest because skin changes were reported to be the earliest noticeable consequence of drug abuse prompting earlier intervention and treatment. Although hair is an annex of skin, alterations on hair structure due to drug use have not been demonstrated. This study represents the first report on ultra-structural hair alterations of drug abusers. We have investigated ultra-structure of the hair samples obtained from 6 cocaine, 6 heroin, 7 cannabis and 4 lysergic acid diethylamide (LSD) abusers by scanning electron microscope (SEM). SEM analysis of hair samples gave us drug-specific discriminating alterations. We suggest that results of this study will make a noteworthy contribution to cutaneous alterations associated with drug abuse which are regarded as the earliest clinical manifestations, and this SEM approach is a very specific and effective tool in the detection of abuse of respective drugs, leading early treatment. PMID:26309532

  3. Automated defect review of the wafer bevel with a defect review scanning electron microscope

    NASA Astrophysics Data System (ADS)

    McGarvey, Steve; Kanezawa, Masakazu

    2009-03-01

    One of the few remaining bastions of non-regulated Integrated Circuit defectivity is the wafer bevel. Recent internal Integrated Circuit Manufacturing studies have suggested that the edge bevel may be responsible for as much as a two to three percent yield loss during a defect excursion on the manufacturing line and a one to two percent yield loss during ongoing wafer manufacturing. A new generation of defect inspection equipment has been introduced to the Research and Development, Integrated Circuit, MEM's and Si wafer manufacturing markets that has imparted the ability for the end equipment user to detect defects located on the bevel of the wafer. The inherent weakness of the current batch of wafer bevel inspection equipment is the lack of automatic discrete defect classification data into multiple, significant classification bins and the lack of discrete elemental analysis data. Root cause analysis is based on minimal discrete defect analysis as a surrogate for a statistically valid sampling of defects from the bevel. This paper provides a study of the methods employed with a Hitachi RS-5500EQEQ Defect Review Scanning Electron Microscope (DRSEM) to automatically capture high resolution/high magnification images and collect elemental analysis on a statistically valid sample of the discrete defects that were located by a bevel inspection system.

  4. Anchoring structure of the calvarial periosteum revealed by focused ion beam/scanning electron microscope tomography

    PubMed Central

    Hirashima, Shingo; Ohta, Keisuke; Kanazawa, Tomonoshin; Uemura, Kei-ichiro; Togo, Akinobu; Yoshitomi, Munetake; Okayama, Satoko; Kusukawa, Jingo; Nakamura, Kei-ichiro

    2015-01-01

    An important consideration in regeneration therapy is the fact that the tissue surrounding an organ supports its function. Understanding the structure of the periosteum can contribute to more effective bone regeneration therapy. As a cellular source, the periosteum also assists bone growth and fracture healing; this further necessitates its direct contact with the bone. However, its anchoring strength appears to be inexplicably stronger than expected. In this study, we used focused ion beam/scanning electron microscope tomography to investigate ultrathin serial sections as well as the three dimensional ultrastructure of the periosteum to clarify the architecture of its anchoring strength, as such assessments are challenging using conventional methods. We discovered perforating fibres that arise from the bone surface at 30 degree angles. Additionally, the fibres across the osteoblast layer were frequently interconnected to form a net-like structure. Fibroblast processes were observed extending into the perforating fibres; their morphologies were distinct from those of typical fibroblasts. Thus, our study revealed novel ultrastructures of the periosteum that support anchorage and serve as a cellular source as well as a mechanical stress transmitter. PMID:26627533

  5. SEM analysis of ionizing radiation effects in linear integrated circuits. [Scanning Electron Microscope

    NASA Technical Reports Server (NTRS)

    Stanley, A. G.; Gauthier, M. K.

    1977-01-01

    A successful diagnostic technique was developed using a scanning electron microscope (SEM) as a precision tool to determine ionization effects in integrated circuits. Previous SEM methods radiated the entire semiconductor chip or major areas. The large area exposure methods do not reveal the exact components which are sensitive to radiation. To locate these sensitive components a new method was developed, which consisted in successively irradiating selected components on the device chip with equal doses of electrons /10 to the 6th rad (Si)/, while the whole device was subjected to representative bias conditions. A suitable device parameter was measured in situ after each successive irradiation with the beam off.

  6. In situ probing electrical response on bending of ZnO nanowires inside transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Liu, K. H.; Gao, P.; Xu, Z.; Bai, X. D.; Wang, E. G.

    2008-05-01

    In situ electrical transport measurements on individual bent ZnO nanowires have been performed inside a high-resolution transmission electron microscope, where the crystal structures of ZnO nanowires were simultaneously imaged. A series of consecutively recorded current-voltage (I-V) curves along with an increase in nanowire bending show the striking effect of bending on their electrical behavior. The bending-induced changes of resistivity, electron concentration, and carrier mobility of ZnO nanowires have been retrieved based on the experimental I-V data, which suggests the applications of ZnO nanowires as nanoelectromechanical sensors.

  7. Enhanced microscopic nonlinear optical properties of novel Y-type chromophores with dual electron donor groups

    NASA Astrophysics Data System (ADS)

    Tang, Xiang; Pan, Lin; Jia, Kun; Tang, Xianzhong

    2016-03-01

    In this Letter, novel Y-type chromophores with dual electron donor groups, containing either styryl or azobenzene based π-conjugated bridge structures, were synthesized and their chemical structures, molecular configuration, microscopic optical properties as well as thermal properties were systematically characterized. The experimental results indicated that eight times increasing of second-order molecular hyperpolarizability as well as 50-100 nm blue shift of maximum absorption band for azobenzene based chromophore were observed by introducing Y-type dual electron donor groups, which was derived from the highly efficient 'total charge transfer' in this kind of chromophore as confirmed by the density functional theory calculation.

  8. Concurrent in situ ion irradiation transmission electron microscope

    SciTech Connect

    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. Charging compensation of alumina samples by using an oxygen microinjector in the environmental scanning electron microscope.

    PubMed

    Quan, Xueling; Ji, Yuan; Zhang, Hong; Zhang, Yinqi; Xu, Xuedong; Zhong, Taoxing

    2006-01-01

    A gas microinjector system was set up in an environmental scanning electron microscope (ESEM) to create an oxygen atmosphere around the alumina samples for the charging compensation under a pressure between 2 x 10(-5) Pa approximately 2 x 10(-2) Pa. At low pressures, the skirt effect of the electron scattering can be degraded, which results in improvement of the imaging contrast and increase of the signal/noise ratio. The sample current (I(SC)) and the Duane-Hunt limit were measured to evaluate the charging effect. PMID:17063769

  10. Experimental evaluation of environmental scanning electron microscopes at high chamber pressure.

    PubMed

    Fitzek, H; Schroettner, H; Wagner, J; Hofer, F; Rattenberger, J

    2015-11-01

    In environmental scanning electron microscopy (ESEM) high pressure applications have become increasingly important. Wet or biological samples can be investigated without time-consuming sample preparation and potential artefacts from this preparation can be neglected. Unfortunately, the signal-to-noise ratio strongly decreases with increasing chamber pressure. To evaluate the high pressure performance of ESEM and to compare different electron microscopes, information about spatial resolution and detector type is not enough. On the one hand, the scattering of the primary electron beam increases, which vanishes the contrast in images; and on the other hand, the secondary electrons (SE) signal amplification decreases. The stagnation gas thickness (effective distance the beam has to travel through the imaging gas) as well as the SE detection system depend on the microscope and for a complete and serious evaluation of an ESEM or low vacuum SEM it is necessary to specify these two parameters. A method is presented to determine the fraction of scattered and unscattered electrons and to calculate the stagnation gas thickness (θ). To evaluate the high pressure performance of the SE detection system, a method is presented that allows for an analysis of a single image and the calculation of the signal-to-noise ratio of this image. All investigations are performed on an FEI ESEM Quanta 600 (field emission gun) and an FEI ESEM Quanta 200 (thermionic gun). These methods and measurements should represent opportunities for evaluating the high pressure performance of an ESEM. PMID:26173072

  11. ELECTRON MICROSCOPIC EXAMINATION OF THE SITES OF NUCLEAR RNA SYNTHESIS DURING AMPHIBIAN EMBRYOGENESIS

    PubMed Central

    Karasaki, Shuichi

    1965-01-01

    The site of H3-uridine incorporation and the fate of labeled RNA during early embryo-genesis of the newt Triturus pyrrhogaster were studied with electron microscopic autoradiography. Isolated ectodermal and mesodermal tissues from the embryos were treated in H3-uridine for 3 hours and cultured in cold solution for various periods before fixation with OsO4 and embedding in Epon. At the blastula stage, the only structural component of the nucleus seen in electron micrographs is a mass of chromatin fibrils. At the early gastrula stage, the primary nucleoli originate as small dense fibrous bodies within the chromatin material. These dense fibrous nucleoli enlarge during successive developmental stages by the acquisition of granular components 150 A in diameter, which form a layer around them. Simultaneously larger granules (300 to 500 A) appear in the chromatin, and they fill the interchromatin spaces by the tail bud stage. Autoradiographic examination has demonstrated that nuclear RNA synthesis takes place in both the nucleolus and the chromatin, with the former consistently showing more label per unit area than the latter. When changes in the distribution pattern of radioactivity were studied 3 to 24 hours after immersion in isotope at each developmental stage, the following results were obtained. Labeled RNA is first localized in the fibrous region of the nucleolus and in the peripheral region of chromatin material. After longer culture in non-radioactive medium, labeled materials also appear in the granular region of the nucleolus and in the interchromatin areas. Further incubation gives labeling in cytoplasm. PMID:19866688

  12. Characterization of electron microscopes with binary pseudo-random multilayer test samples

    SciTech Connect

    Yashchuk, Valeriy V; Conley, Raymond; Anderson, Erik H; Barber, Samuel K; Bouet, Nathalie; McKinney, Wayne R; Takacs, Peter Z; Voronov, Dmitriy L

    2010-09-17

    Verification of the reliability of metrology data from high quality x-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [Proc. SPIE 7077-7 (2007), Opt. Eng. 47(7), 073602-1-5 (2008)} and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [Nucl. Instr. and Meth. A 616, 172-82 (2010)]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi2/Si multilayer coating with pseudo randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize x-ray microscopes. Corresponding work with x-ray microscopes is in progress.

  13. Characterization of electron microscopes with binary pseudo-random multilayer test samples

    NASA Astrophysics Data System (ADS)

    Yashchuk, Valeriy V.; Conley, Raymond; Anderson, Erik H.; Barber, Samuel K.; Bouet, Nathalie; McKinney, Wayne R.; Takacs, Peter Z.; Voronov, Dmitriy L.

    2011-09-01

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [1,2] and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [5]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi 2/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  14. Characterization of Electron Microscopes with Binary Pseudo-random Multilayer Test Samples

    SciTech Connect

    V Yashchuk; R Conley; E Anderson; S Barber; N Bouet; W McKinney; P Takacs; D Voronov

    2011-12-31

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [1] and [2] and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [5]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi2/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  15. Characterization of electron microscopes with binary pseudo-random multilayer test samples

    SciTech Connect

    Yashchuk, V.V.; Conley, R.; Anderson, E.H.; Barber, S.K.; Bouet, N.; McKinney, W.R.; Takacs, P.Z. and Voronov, D.L.

    2010-12-08

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binarypseudo-random (BPR) gratings and arrays has been suggested and and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer. Here we describe the details of development of binarypseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi{sub 2}/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML testsamples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  16. Low-loss electron images of uncoated photoresist in the scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Wells, Oliver C.

    1986-09-01

    Low voltage scanning electron microscopy is an important part of microelectronic inspection technique. This makes it possible to examine devices without changing the electrical properties, and to examine nonconducting samples such as photoresist without the use of a surface metal layer. The secondary electron imaging method suffers, however, from the difficulty that the image can be spoiled by slight charging of the specimen by the incident electron beam. This problem can be solved by the use of the low-loss electron image.

  17. Electron-microscopic and chemical identification of an individual grain in the newly formed cementite in spheroidized pearlitic 12Kh1MF steel

    NASA Astrophysics Data System (ADS)

    Gerasimov, V. V.

    2015-12-01

    The microstructure of pearlitic 12Kh1MF steel having spent its service life is studied with a Neophot-32 optical microscope. A cementite grain is identified and its elemental composition is determined using a multipurpose EVO-50 scanning electron microscope equipped with an EDS/WDS X-ray spectrometer. A newly formed grain of alloyed cementite is detected at a triple junction. The diffusion processes that occur in loaded steel are refined.

  18. Rapid Nondestructive Analysis of Threading Dislocations in Wurtzite Materials Using the Scanning Electron Microscope

    NASA Astrophysics Data System (ADS)

    Naresh-Kumar, G.; Hourahine, B.; Edwards, P. R.; Day, A. P.; Winkelmann, A.; Wilkinson, A. J.; Parbrook, P. J.; England, G.; Trager-Cowan, C.

    2012-03-01

    We describe the use of electron channeling contrast imaging in the scanning electron microscope to rapidly and reliably image and identify threading dislocations (TDs) in materials with the wurtzite crystal structure. In electron channeling contrast imaging, vertical TDs are revealed as spots with black-white contrast. We have developed a simple geometric procedure which exploits the differences observed in the direction of this black-white contrast for screw, edge, and mixed dislocations for two electron channeling contrast images acquired from two symmetrically equivalent crystal planes whose g vectors are at 120° to each other. Our approach allows unambiguous identification of all TDs without the need to compare results with dynamical simulations of channeling contrast.

  19. Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope.

    PubMed

    Li, Meng; Xu, Chunkai; Zhang, Panke; Li, Zhean; Chen, Xiangjun

    2016-08-01

    We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam. PMID:27587179

  20. Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope

    NASA Astrophysics Data System (ADS)

    Li, Meng; Xu, Chunkai; Zhang, Panke; Li, Zhean; Chen, Xiangjun

    2016-08-01

    We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam.